From: Rob Bamford [mailto:rbamford@ndep.nv.gov] Sent: Tuesday, August 24, 2010 7:36 PM To: 'French.Chuck@epamail.epa.gov'; Branscome, Marvin R. Subject: pre

- treatment cost docs & projects



### Hello gentlemen,

Here's some info on pre

- treatment NvMACT projec ts and cost. Of note, the Queenstake document was not an application, but has technical data and my handwriting on one of the pages notes the project estimated cost. Queenstake was required to submit a plan under the consent decree as opposed to a NvMACT application.

Hope this helps,

- Rob

See attached documents: Queenstake ore dryer.pdf NMCP Application AC 4

- 6.pdf Goldstrike_NvMACT_Autoclave1

- 3_08102010.pdf Goldquarry pre

- heater.pdf

Rob Bamford Supervisor, Nevada Mercury Control Program Nevada Division of Environmental Pr otection Bureau of Air Quality Planning Phone: 775

- 687

- 9330 Cell: 775

- 315

- 3655 Fax: 775

- 687

- 6396 E

- mail: rbamford@ndep.nv.gov

# Nevada Mercury Control Program Application for Minor Modification:

Systems 66C and 66D, Autoclave Circuits 3 and 4

B

ARRICK 

## G OLDSTRIKE 

## M INES 

## I NC



## .

June 2010Page 1 

## Table of Contents

General Information ........................................................................................................... Page 2

APPLICATION

Mercury Operating Permit to Construc t Application Cover Page ......................................Page 3 General Company Information ..........................................................................................Page 4 -General Company Information Form and Application Information (4 Pages)

Additional Forms

Mercury Unit Application Form ................................................................................ Appendix 1

- 

### Section 1A: System 66C, TU4.016, Autoclave Circuit 3, Autoclave #4 .............................. 3

- 

### Section 2A: System 66C, TU4.016, Autoclave Circuit 3, Autoclave #4 .............................. 3

- 

### Section 3A: System 66C, TU4.016, Autoclave Circuit 3, Autoclave #4 .............................. 4

- 

### Section 1B: System 66D, TU4.017, Autoclave Circuit 3, Autoclave #5 .............................. 5

- 

### Section 2B: System 66D, TU4.017, Autoclave Circuit 3, Autoclave #5 .............................. 5

- 

### Section 3B: System 66D, TU4.017, Autoclave Circuit 3, Autoclave #5 .............................. 6

- 

### Section 1C: System 66D, TU4.018, Autoclave Circuit 4, Autoclave #6 .............................. 7

- 

### Section 2C: System 66D, TU4.018, Autoclave Circuit 4, Autoclave #6 .............................. 7

- 

### Section 3C: System 66D, TU4.018, Autoclave Circuit 4, Autoclave #6 .............................. 8

- 

### Section 4: System 66C & 66D, TU4.016 – TU4.018, Autoclave Circuits 3 & 4,

Autoclaves #4 - #6

............................................................................................................................... 9

- 

### Section 5: System 66C & 66D, TU4.016 – TU4.018, Autoclave Circuits 3 & 4,

Autoclaves #4 - #6 ............................................................................................................................. 10

- 

### Section 6: System 66C & 66D, TU4.016 – TU4.018, Autoclave Circuits 3 & 4,

Autoclaves #4 - #6 ............................................................................................................................. 11

- 

### Section 7: System 66C & 66D, TU4.016 – TU4.018, Autoclave Circuits 3 & 4,

Autoclaves #4 - #6 ............................................................................................................................. 12 

### Monitoring/Testing Plan ............................................................................................ Appendix 2 Nevada MACT (NvMACT) Analysis ........................................................................ Appendix 3

De minimis emissions Request .................................................................................. Appendix 4 Application Certification ........................................................................................... Appendix 5Page 2 

### State of Nevada Division of Environmental Protection Bureau of Air Pollution Control



# APPLICATION FOR MERCURY OPERATING PE RMIT TO CONSTRUCT

Please return to: Nevada Divisi on of Environmental Protection Bureau of Air Pollution Control, Permitting Branch 901 South Stewart Street Carson City, Nevada 89701-5249 (775) 687-9350 FAX (775) 687-6396



## General Information

• This application is available from the Bureau of Air Pollution Control in a Microsoft Word file, or on the

internet at http://www.ndep.nv.gov/bapc. All information required in the application may be computer generated and submitted to the Bureau on compact disk(s) or DVD(s). In addition, one printed copy must be submitted.

• All information required by the “General Company Information” and by the relevant forms in the Appendices

must be completed.

• The application filing fee required by NAC 445B.3689 must be submitted with the completed application.

Checks must be made payable to: “Nevada State Treasurer, Enviro nmental Protection”.

• This application packet shall be used for Tier 1, Tier 2 thermal units that emit mercury, for construction of

new thermal units that emit mercury, for de minimis designation and construction and installation projects for thermal units that emit mercury at new and existing stationary sources.

• An application for a mercury operating permit to constr uct must be signed by a responsible official, as defined in Section NAC 445B.297.1. The certification/signature page is contained in Appendix 5.

• All items in the application must be addressed. If an item does not apply, please indicate so with “N/A” or similar notation in the appropriate blank. All other information must be provided. Incomplete applications will be returned to the responsible official.Page 3 

# Application for Mercury Air Quality

Operating Permit to ConstructPage 4 GENERAL COMPANY INFORMATION

All applicants shall complete each item or explain in the sp ace provided why no information is needed. Please specify "N/A" (Not Applicable) if necessary. The application will be returned to the applicant if it is deemed incomplete.

1. COMPANY NAME AND ADDRESS THAT ARE TO APPEAR ON THE OPERATING PERMIT [NAC 445B.3671.1 and NAC 445B.3681.1]:

Barrick Goldstrike Mines Inc. (Name)

P.O. Box 29 (Address)

Elko NV 89803 (City) (State) (Zip Code)

2. Owner's Name and Address [NAC 445B.295.1]:

Barrick Gold Corporation (Name)

BCE Place, Canada Trust Tower, Suite 3700.161 Bay Street, P.O. Box 212 (Address)

Toronto Ontario M5J2S1 (City) (State) (Zip Code)

3. Source Name and Mailing Address, if differen t from #1 [NAC 445B.3671.1 and NAC 445B.3681.1]:

Same as #1 (Name)

(Address)

(City) (State) (Zip Code)

4. Physical Location of Stationary Source [NAC 445B.3671.2 and NAC 445B.3681.7]: (if no physical address, describe location, e.g., 4 miles south of I-80 at xx Interchange)

27 miles north of Carlin, Nevada, off state route 766

Township(s) * Range(s) * Section(s) * * Section s 1 through 4, T35N, R49E; Sections 12 through 15, 21 through 28, and 33 through 36, T36N, R49E;

Sections 7 through 9, 16 through 21, and 28 through 32, T36N, R50E, MDB&M (HA61)

5. Responsible Official Name, T itle and Address [NAC 445B.295.1]:

Joseph Giraudo Environmental Manager (Name) (Title)

Same as #1 (Address)

(City) (State) (Zip Code)

(775) 778-8140 (775) 778-8262 jgiraudo@barrick.com (Telephone #) (FAX #) (E-mail address)Page 5 GENERAL COMPANY INFORMATION (CONTINUED)

6. Plant Manager or Other Appropriate C ontact [NAC 445B.3671.1 and NAC 445B.3681.1]:

Carly Keeney Environmental Engineer (Name) (Title)

Same as #1 (Address)

(City) (State) (Zip Code)

(775) 778-8157 (775) 778-8262 ckeeney@barrick.com (Telephone #) (FAX #) (E-mail address)

7. If records required under the operating permit will be kept at a location other than the source, specify that location [NAC 445B.3671.5 and NAC 445B.3681].

N/A. Records will be kept on site. (Name)

(Address)

(City) (State) (Zip Co de)Page 6 APPLICATION INFORMATION

8. This application is submitted for (please check appropriate box below):


### Phase 1 Application

Tier 1 Unit(s) – Please provide the following:

a. An identification and description of any equipment for control of mercury emissions from all existing thermal units that emit mercury, including any presumptive NvMACT controls. In addition to the identification and description, please complete Section 5 of the Mercury Unit application form in Appendix 1. A separate Mercury Unit application form is required for each thermal unit that emits mercury. [NAC 445B.3673.1] b. A proposed monitoring plan for each therma l unit that emits mercury consistent with the requirements of NAC 445B.3673.2(a). Include the plan in Appendix 2. c. For each requested mercury early reduction credit, the additional controls th at are proposed to be implemented to reduce mercury emissions. [NAC 445B.3671.6]



### Tier 2 Unit(s) – Please provide the following:

a. An identification and description of any equipment for control of mercury emissions from all existing thermal units that emit mercury, including any presumptive NvMACT controls. In addition to the identification and description, please complete Section 5 of the Mercury Unit application form in Appendix 1. A separate Mercury Unit application form is required for each thermal unit that emits mercury. [Section 33.1 of amended NAC 445B] b. A proposed monitoring plan for each therma l unit that emits mercury consistent with the requirements of Section 33.2(b) of amended NAC 445B. Include the plan in Appendix 2.



### Phase 2 Application

Tier 1 or Tier 2 Unit(s) – Please provide the following:

a. A proposed monitoring plan consistent with the requirements of NAC 445B.3675.2. Include the plan in Appendix 2. b. The NvMACT analysis for each thermal unit that emits mercury c onsistent with the requirements of NAC 445B.3675.1. Include the analysis in Appendix 3.


### New or Modified Thermal Unit that Emits Mercury

a. Please provide the NvMACT analysis for each thermal unit that emits mercury consistent with the requirements of NAC 445B.3681.6. Include the analysis in Appendix 3.


### Request for De Minimis Designation

a. For a request for determination of de minimis mercury emissions, include a de minimis demonstration in Appendix 4. De minimis st atus is considered for each thermal unit. Demonstration must be at the individual unit level, but include cumulative impact of all de minimis units at a facility. [NAC 445B.3613 and NAC 445B.3657.3] b. De minimis demonstration must include, at a minimum: identification of the proposed thermal unit, a process description, location, unit manufacturer, un it model, serial number and fuel type used (or specify if electric). Identify if any exhaust stacks are shared and if mercury emission controls are utilized. [NAC 445B.295] c. Include potential to emit values based on unit operation at maximum design capacity at 8,760 hours per year. Supply laboratory test results, performance stack test results and calculations implemented to calculate potential to emit mercury emissions. Include a thorough discussion of any assumptions. [NAC 445B.295] d. Identify under what Air Quality Operating Permit the proposed units are contained and if the proposed units are designated as “insignificant” or “non-permitted items.” [NAC 445B.295]Page 7 APPLICATION INFORMATION (CONTINUED)

9. The application must also contain: a. An identification of each thermal unit that emits mercury. In addition to the identification of each thermal unit that emits mercury, please complete Section 1 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.2 and NAC 445B.3681.2] b. A description of the production rates, operating sche dules, fuels, fuel use and raw materials to be used for each thermal unit that emits mercury. In additi on to the description, pl ease complete Sections 2 and 3 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emit s mercury. [NAC 445B.3671.3 and NAC 445B.3681] c. Limitations on the operation of stationary source or thermal unit that emits mercury or any work practices which may affect mercury emissions from th e thermal unit that emits mercury. Use Sections 4 and 5 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.4 and NAC 445B.3681.4] d. Requested emissions limits. Use Section 7 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.7 and NAC 445B.3681.7]

11. Will the construction occur in more than one phase? Yes No

If the construction will occur in more than one phase, please provide the projected date of the commencement for each phase of construction (include addi tional phases if necessary): [NAC 445B.3687]

Phase 1: Phase 2: Phase 3:

12. For Application Submittal: Please remove the cover page, Table of Contents and General Information page. Submit the remainder of the application packet as your formal application. This should consist of, at a minimum, the Mercury Operating Permit to Construct Application cover page, the genera l Company Information and Application Information, and any applicable Appendices.Appendix 1, Page 1 

# Appendix 1

THERMAL MERCURY EMITTING UNIT APPLICATION FORMAppendix 1, Page 2 

### Instructions

PLEASE RESPOND SEPARATELY TO ITEMS 1 through 7 FOR EACH EMISSION UNIT, as appropriate. Each emission unit at the stationary source must be identified by completion of the application form contained in this appendix. The forms may be duplicated for as many thermal mercury emission units as needed. Complete all applicable attachments ( Appendix 1 ) included in this application package [NAC 445B.295].

Section 1. Equipment Description : Describe the processes and products by SIC, including any associated with an alternative operating scenario identified in this application, model number, manufacture date, dimensions and UTM coordinates. Section 2. Design Rate /Operating Parameters : Describe all production ra tes, operating schedules and materials used in the process. Section 3. Fuel Usage : Describe all fuels and fuel usage. Section 4. Pollution Control Equipment/Exhaust Stack Parameters : Identify and describe all air pollution control equipment. Section 5. Work Practice Standards : provide information on limitations on the operation or any standards for work practices which affect emissions for a ll regulated air pollutants. [NAC 445B.295.5] Section 6. Compliance Monitoring Devices and Activities : Identify and describe any equipment for the control of air pollution and any devices or activities for monitoring compliance with emission limitations. Section 7. Requested Emission Limits : Provide the requested emission limits for each emission unit. Include the emission rates of total mercury . The emission rates must be described in pounds per hour and pounds per year and any other units of measure for mercury emissions as may be proposed.

Alternative Operating Scenarios : Complete a separate application form for each emission unit having an alternative operating scenario. (A common example of an alternative operating scenario is a steam boiler that utilizes natural gas as the primary fuel, but may combust diesel fuel as an alternate fuel source) . Please check the box in the upper right hand corner of each application form for emission units requesting an alternative operating scenario. Additionally, for each emi ssion unit application form requesting an alternative operating scenario: 1. Define each alternative operating scenario; 2. Provide an alternative monitoring plan for each unit, for which an alternative operating scenario is requested, in Appendix 2, if different from the m onitoring plan provided for the primary operating scenario. Contemporaneous log entries must be provided every time the source changes from one scenario to another.Appendix 1, Page 3 System 66C, TU4.016 (Autoclave Circuit 3, Autoclave #4)



### THERMAL MERCURY EMITTING UNIT APPLICATION FORM MERCURY OPERATING PE RMIT TO CONSTRUCT

Check here if this is an alternative operating scenario 

### Section 1A - Equipment Description

a. Type of equipment System 66C, TU4.016 (Autoclave Circuit 3, Autoclave #4)

b. Standard Industrial Classification (SIC) Code 1041

c. Manufacturer of equipment Eaton

d. Model number not specified Serial number not specified *Equip. number not specified

e. Date equipment manufactured: 1992

f. UTM Coordinates 4,536,011 meters N; 554,734 meters E; Zone 11 (Please specify NAD 27 or NAD 83 ; Method used to obtain coordinates: )


### g. Basic equipment dimensions (feet): L not specified W not specified H not specified *The equipment number is the facility's own num bering system for this piece of equipment.



### Section 2A - Design Rate/Operating Parameters



### a. Maximum design capacity (tons per hour) 200

b. Requested operating rate (tons per hour)*

c. Requested operating time: (time of day)* to

Hours per day 0-24 Days per year 365, 8,760 hr/yr

d. Batch load or charge weight (tons) (if applicable) N/A

e. Total hours required to process batch or charge (if applicable) N/A

f. Maximum operating rate (tons per year) not specified

g. Requested operating rate (tons per year)*

f. Type of material processed ore

*Note: Please complete if other than th e maximum design capacity (tons per hour and tons per year) and/or the maximum hours of operation (24 hours per day, 8,760 hours per year) are being requested. The permit will be limited to these values.Appendix 1, Page 4 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66C - TU4.016

Section 3A - Fuel Usage / Heat Source

Electric Unit 

# □

Type of Fuel Amount Used Per Hour Heat Content (specify in Btus) Ash Content

(% by weight) Sulfur Content ( % by weight) Trace Elements

(% by weight) Oil- Specify Type(s)

none gallons N/A N/A N/A N/A

none gallons N/A N/A N/A N/A
Gasoline none gallons N/A N/A N/A N/A Propane none cubic feet N/A N/A N/A N/A
Natural Gas none cubic feet N/A N/A N/A N/A
*Waste Oil none gallons N/A N/A N/A N/A
Other none N/A N/A N/A N/A

Type of

Coal Fuel Amount Used Per Hour (tons) Heat Content (specify in BTUs) Ash Content

(% by weight) Sulfur Content

(% by weight) Trace Elements

(% by weight) Percent moisture Percent volatile
matter Percent fixed carbon

Coal - Specify Type(s)

none N/A N/A N/A N/A N/A N/A N/A N/A

If more than one type of fuel is combusted, under this opera ting scenario please specify prim ary fuel and percentage on a maximum hourly and annual ba sis (if fuel blending is the primary fuel, identif y percentages of each fuel blended). Attach additional information to this form if necessary.

*Firing of waste oil will require multi metals test to insure fuel is non-hazardous.Appendix 1, Page 5 System 66D, TU4.017 (Autoclave Circuit 3, Autoclave #5)



### THERMAL MERCURY EMITTING UNIT APPLICATION FORM MERCURY OPERATING PE RMIT TO CONSTRUCT

Check here if this is an alternative operating scenario 

### Section 1B - Equipment Description

a. Type of equipment System 66D, TU4.017 (Autoclave Circuit 3, Autoclave #5)

b. Standard Industrial Classification (SIC) Code 1041

c. Manufacturer of equipment Eaton

d. Model number not specified Serial number not specified *Equip. number not specified

e. Date equipment manufactured: 1992

f. UTM Coordinates 4,536,011 meters N; 554,734 meters E; Zone 11 (Please specify NAD 27 or NAD 83 ; Method used to obtain coordinates: )


### g. Basic equipment dimensions (feet): L not specified W not specified H not specified *The equipment number is the facility's own num bering system for this piece of equipment.



### Section 2B - Design Rate /Operating Parameters



### a. Maximum design capacity (tons per hour) 200

b. Requested operating rate (tons per hour)*

c. Requested operating time: (time of day)* to

Hours per day 0-24 Days per year 365, 8,760 hr/yr

d. Batch load or charge weight (tons) (if applicable) N/A

e. Total hours required to process batch or charge (if applicable) N/A

f. Maximum operating rate (tons per year) not specified

g. Requested operating rate (tons per year)*

f. Type of material processed ore

*Note: Please complete if other than th e maximum design capacity (tons per hour and tons per year) and/or the maximum hours of operation (24 hours per day, 8,760 hours per year) are being requested. The permit will be limited to these values.Appendix 1, Page 6 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66D - TU4.017

Section 3B - Fuel Usage / Heat Source

Electric Unit 

# □

Type of Fuel Amount Used Per Hour Heat Content (specify in Btus) Ash Content

(% by weight) Sulfur Content ( % by weight) Trace Elements

(% by weight) Oil- Specify Type(s)

none gallons N/A N/A N/A N/A

none gallons N/A N/A N/A N/A
Gasoline none gallons N/A N/A N/A N/A Propane none cubic feet N/A N/A N/A N/A
Natural Gas none cubic feet N/A N/A N/A N/A
*Waste Oil none gallons N/A N/A N/A N/A
Other none N/A N/A N/A N/A

Type of

Coal Fuel Amount Used Per Hour (tons) Heat Content (specify in BTUs) Ash Content

(% by weight) Sulfur Content

(% by weight) Trace Elements

(% by weight) Percent moisture Percent volatile
matter Percent fixed carbon

Coal - Specify Type(s)

none N/A N/A N/A N/A N/A N/A N/A N/A

If more than one type of fuel is combusted, under this opera ting scenario please specify prim ary fuel and percentage on a maximum hourly and annual ba sis (if fuel blending is the primary fuel, identif y percentages of each fuel blended). Attach additional information to this form if necessary.

*Firing of waste oil will require multi metals test to insure fuel is non-hazardous.Appendix 1, Page 7 System 66D, TU4.018 (Autoclave Circuit 4, Autoclave #6)



### THERMAL MERCURY EMITTING UNIT APPLICATION FORM MERCURY OPERATING PE RMIT TO CONSTRUCT

Check here if this is an alternative operating scenario 

### Section 1C - Equipment Description

a. Type of equipment System 66D, TU4.018 (Autoclave Circuit 4, Autoclave #6)

b. Standard Industrial Classification (SIC) Code 1041

c. Manufacturer of equipment Eaton

d. Model number not specified Serial number not specified *Equip. number not specified

e. Date equipment manufactured: 1992

f. UTM Coordinates 4,536,011 meters N; 554,734 meters E; Zone 11 (Please specify NAD 27 or NAD 83 ; Method used to obtain coordinates: )


### g. Basic equipment dimensions (feet): L not specified W not specified H not specified *The equipment number is the facility's own num bering system for this piece of equipment.



### Section 2C - Design Rate/Operating Parameters



### a. Maximum design capacity (tons per hour) 200

b. Requested operating rate (tons per hour)*

c. Requested operating time: (time of day)* to

Hours per day 0-24 Days per year 365, 8,760 hr/yr

d. Batch load or charge weight (tons) (if applicable) N/A

e. Total hours required to process batch or charge (if applicable) N/A

f. Maximum operating rate (tons per year) not specified

g. Requested operating rate (tons per year)*

f. Type of material processed ore

*Note: Please complete if other than th e maximum design capacity (tons per hour and tons per year) and/or the maximum hours of operation (24 hours per day, 8,760 hours per year) are being requested. The permit will be limited to these values.Appendix 1, Page 8 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66D - TU4.018

Section 3C - Fuel Usage / Heat Source

Electric Unit 

# □

Type of Fuel Amount Used Per Hour Heat Content (specify in Btus) Ash Content

(% by weight) Sulfur Content ( % by weight) Trace Elements

(% by weight) Oil- Specify Type(s)

none gallons N/A N/A N/A N/A

none gallons N/A N/A N/A N/A
Gasoline none gallons N/A N/A N/A N/A Propane none cubic feet N/A N/A N/A N/A
Natural Gas none cubic feet N/A N/A N/A N/A
*Waste Oil none gallons N/A N/A N/A N/A
Other none N/A N/A N/A N/A

Type of

Coal Fuel Amount Used Per Hour (tons) Heat Content (specify in BTUs) Ash Content

(% by weight) Sulfur Content

(% by weight) Trace Elements

(% by weight) Percent moisture Percent volatile
matter Percent fixed carbon

Coal - Specify Type(s)

none N/A N/A N/A N/A N/A N/A N/A N/A

If more than one type of fuel is combusted, under this opera ting scenario please specify prim ary fuel and percentage on a maximum hourly and annual ba sis (if fuel blending is the primary fuel, identif y percentages of each fuel blended). Attach additional information to this form if necessary.

*Firing of waste oil will require multi metals test to insure fuel is non-hazardous.Appendix 1, Page 9 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: Systems 66C & 66D - TU4.016-TU4.018 (Autoclaves #4 - #6 share a common stack)

Section 4 - Pollution Control Equipment/ Exhaust Stack Parameters (this section must be completed) -Complete for emissions exhausting through a stack, chimney or vent : (baghouse, wet scrubber, cyclone, sulfur impregnated carbon filter, uncontrolled stack, etc.) Control #1 Control #2

Type of Control (See Note 1 ) existing: venturi wet dust scrubber proposed: secondary venturi scrubber, scrubber mist eliminator, gas cooling tower, condenser, wet gas separator, carbon filter
Pollutant(s) Controlled particulates and mercury



### Manufacturer existing: Hosokawa proposed: TBD

Manufacturer's Guarantee (see Note 2 ) N/A

Stack height (feet from ground level) 100

Stack inside diameter (feet) 4.5

Temperature (°F) at design capacity approximately 110

Stack exit velocity (feet per second) approximately 17

Gas volume flow rate: Actual cubic feet per minute 

### approximately 16,200

Gas volume flow rate: Dry standard cubic feet per minute 

### approximately 11,820

Unusual stack characteristics (e.g. raincap, horizontal discharge) 

### N/A

Note 1 : Specify "uncontrolled" if no pollution control device is installed. Note 2 : Manufacturer's guarantee of control efficiency must be attached to this form.Appendix 1, Page 10 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: Systems 66C & 66D - TU4.016-TU4.018 (Autoclaves #4 - #6 share a common stack)

Section 5 - Identify and Describe Work Practice Standards, Etc. (attach additional pages if necessary

(Eg., 1. Baghouse housing a nd bags will be inspected weekly for holes/leaks.)



### Work Practices:

Primary Venturi Wet Dust Scrubbers: (a) The pressure drop across each primary venturi wet dust scrubber will be maintained at or below 70 inches of water, based on a 1-hour period. (b) The water flow rate to each primary venturi wet dust scrubber will be maintained at or above 50 gallons per minute, based on a 1-hour period.

Secondary Venturi Scrubber: (a) The pressure drop across the secondary venturi scrubber will be maintained within the manufacturer’s specified range, based on a 1-hour period. (b) The water flow rate to the secondary venturi scrubber will be maintained at or above the manufacturer’s specified range, based on a 1-hour period.

Cooling Tower: (a) The pressure drop across the gas cooling tower will be maintained within the manufacturer’s specified range, based on a 1-hour period. (b) The water flow rate to the gas cooling tower will be maintained at or above the manufacturer’s specified range, based on a 1-hour period.

Condenser: (a) The condenser outlet exhaust temperature will be mainta ined at or below 58° Fahrenheit, based on a 1-hour period.

Carbon Adsorption Bed: (a) Sulfur-impregnated carbon from the carbon adsorption filter will be replaced in accordance with the following schedule: (i) Conduct an initial sampling of the sulfur-impre gnated carbon within 90 days after commencement of operation under this permit. A representative sample shall be taken and analyzed. The sample location will be recorded. Using this sample, the percentage of mercury by weight shall be calculated. Sampling will continue quarterly, at the same sample depth lo cation, until 70% of the carbon loading capacity of 20% by weight is reached. Upon reaching 70% of the carbon loading capacity of 20% by weight, sampling of the carbon will occur mo nthly until 75% of the carbon loadin g capacity of 20% by weight is reached. The carbon will be replaced with an equivalent performing sulfur-impregnated carbon no later than 30 days after reaching 75% of the carbon loading capacity of 20% by weight. The required mercury analysis shall be performed utilizing one of the following methods:

1. EPA method 6020-Inductively Co upled Plasma-Mass Spectrometry; 2. EPA method 7471B- Mercury in Solid or Semisolid Waste (Manual Cold-Vapor Technique); or 3. An alternative test method as approved by the Director. (b) A halogen impregnated carbon may be used in place of the sulfur impregnated carbon upon approval by the Director. Halogen carbon will follow the same sampling and change-out schedule as sulfur-impregnated carbon.Appendix 1, Page 11 

### Section 6 - Identify and Describe Comp liance Monitoring Devices or Activities (attach additional pages if necessary)

(Eg., Emissions from this unit will be monitored by CEMS for mercury.)


### Monitoring and Recordkeeping:

(a) The pressure drop across each primary venturi scrubber will be monitored and recorded once, during each day of operation. (b) The water flow rate to each primary venturi scrubber will be monitored and recorded once, during each day of operation. (c) The pressure drop across the secondary venturi scrubber will be monitored and recorded once, during each day of operation. (d) The water flow rate to the secondary venturi scrubber will be monitored and recorded once, during each day of operation. (e) The pressure drop across the gas cooling tower will be monitored and recorded once, during each day of operation. (f) The water flow rate to the gas cooling tower wi ll be monitored and recorded once during each day of operation. (g) The condenser outlet exhaust temperature will be monitored and recorded once, during each day of operation. (h) The percentage of mercury by weight on the carbon in the carbon adsorption filter will be monitored and recorded quarterly until reaching 70% of the carbon loading capacity of 20%, and then monthly until reaching 75% percent of the carb on loading capacity of 20%.


### Testing Requirements:

Annual Testing

Before the conclusion of th e calendar year, Permittee shall conduct and record a Method 29 (or alternative test method approved by the Director) compliance test for the merc ury on the exhaust stack of TU4.016 through TU4.018.

Annual Reporting

The Permittee shall: 1. Report the mercury co-product on an annual basis. 2. Report the mercury emissions on an annual basis whic h must be based on mercury emissions test data.Appendix 1, Page 12 

### THERMAL 

### MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: Systems 66C & 66D - TU4.016-TU4.018 (Autoclaves #4 - #6 share a common stack)

Section 7 - Proposed Emission Rates

Pollutant Potential to Emit (pounds/hour*) Potential to Emit (tons/year) Calculation (including reference or emissions tests) on Which Emissions Information is Based (attach supporting information including dates of tests/methods, if necessary) Total Mercury (all forms) Total Mercury (alternative emissions limitations) 7.8 x 10 -5 

### gr/dscf See Appendix 3, Page 19 for calculations

*Note: In addition to lb/hr, alternative emissions limitations (e.g., lb/MMBtu, ppm, grains/dsc f) may be requested by the appl icant. If alternative emissions limitations are requested, please clearly describe the units in column 2 above. Use additional lines, as needed.Appendix 2, Page 1 

# Appendix 2

Monitoring Plan For Each:

(Check Appropriate Box) 

# Phase 1, Tier 1; Phase 1, Tier 2; Phase 2; or New or Modified

Thermal Mercury Emitting Unit

### Air Pollution Equipment:

(a) Exhaust gases from TU4.016 through TU4.018 (System 66, Autoclaves 4, 5 and 6) shall be ducted to a control system consisting of:

a. Primary venturi wet dust scrubber b. Secondary venturi wet dust scrubber

c. Gas cooling tower d. Condenser

e. Carbon adsorption bed (b) Stack Parameters

a. Height: 100 Feet b. Diameter: 4.5 Feet

c. Stack Temperature: 110°F d. Flow: Approximately 16,200 ACFM

e. Units TU4.016 through TU4.018 are ducted to a single stack.


### Operating Requirements:

(a) Limitations of operation

a. Mercury emissions from TU4.016 thro ugh TU4.018 shall not exceed 7.8 x 10 -5 gr/dscf. b. Hours i. TU4.016 through TU4.018 may operate 24 hours per day ii. TU4.016 through TU4.018 may operate 8,760 hours per calendar year.



### Work Practices:

Primary Venturi Wet Dust Scrubbers: (a) The pressure drop across each primary venturi wet dust scrubber will be maintained at or below 70 inches of water, based on a 1-hour period. (b) The water flow rate to each primar y venturi wet dust scrubber will be ma intained at or above 50 gallons per minute, based on a 1-hour period.

Secondary Venturi Scrubber: (a) The pressure drop across the secondary venturi scrubber will be maintained within the manufacturer’s specified range, based on a 1-hour period. (b) The water flow rate to the secondary venturi scrubber will be maintained at or above the manufacturer’s specified range, based on a 1-hour period.

Gas Cooling Tower: (a) The pressure drop across the gas cooling tower will be maintained within the manufacturer’s specified range, based on a 1-hour period. (b) The water flow rate to the gas coolin g tower will be maintained at or above the manufacturer’s specified range, based on a 1-hour period.

Condenser: (a) The condenser outlet exhaust temperature will be maintain ed at or below 58° Fahrenheit, based on a 1-hour period.

Carbon Adsorption Bed: (a) Sulfur-impregnated carbon from the carbon adsorption filter will be replaced in accordance with the following schedule: (i) Conduct an initial sampling of the sulfur-impre gnated carbon within 90 days after commencement of operation under this permit. A representative sample shall be taken and analyzed. The sample location will be recorded. Using this sample, the percentage of mercury by weight shall be calculated. Sampling will continue quarterly, at the same sample location, until 70% of the carbon loading capacity of 20% by weight is reached. Upon reaching 70% of the carbon loading capacity of 20% by weight, sampling of the carbon will occur monthly until 75% of the carbon loading capacity of 20% by weight is reached. The carbon will be replaced with an equivalent performing sulfur-impregnated carbon no later than 30 days after reaching 75% of the carbon loading capacity of 20% by weight . The required mercury analysis shall be performedutilizing one of the following methods: 1. EPA method 6020-Inductively Co upled Plasma-Mass Spectrometry; 2. EPA method 7471B- Mercury in Solid or Semisolid Waste (Manual Cold-Vapor Technique); or 3. An alternative test method as approved by the Director. (b) A halogen impregnated carbon may be used in place of the sulfur impregnated carbon upon approval by the Director. Halogen carbon will follow the same sampling and change-out schedule as sulfur-impregnated carbon.



### Monitoring and Recordkeeping:

(a) The pressure drop across each primary venturi scrubber will be monitored and recorded once during each day of operation. (b) The water flow rate to each primary venturi scrubber will be monitored and recorded once during each day of operation. (c) The pressure drop across the secondary venturi scrubber will be monitored and recorded once during each day of operation. (d) The water flow rate to the secondary venturi scrubber will be monitored and recorded once during each day of operation. (e) The pressure drop across the gas cooling tower cooling tower will be monitored and recorded once during each day of operation. (f) The water flow rate to the gas cooling tower will be monitored and recorded once during each day of operation. (g) The condenser outlet exhaust temperature will be monitored and recorded once during each day of operation. (h) The percentage of mercury by weight on the carbon in the carbon adsorption filter will be monitored and recorded quarterly until reaching 70% of the carbon loading capacity of 20%, and then monthly until reaching 75% percent of the carbon loading capacity of 20%.



### Testing Requirements:

Annual Testing

Before the conclusion of th e calendar year, Permittee shall conduct and record a Method 29 (or alternative test method approved by the Director) compliance test for the merc ury on the exhaust stack of TU4.016 through TU4.018.

Annual Reporting

The Permittee shall: 1. Report the mercury co-product on an annual basis. 2. Report the mercury emissions on an annual basis whic h must be based on mercury emissions test data.Appendix 3, Page 1 

# Appendix 3

Nevada MACT Analysis For Each:

(Check Appropriate Box)



# Phase 2; New or Modified; or Not Applicable

Thermal Mercury Emitting UnitAppendix 3, Page 2 

# CONTENTS Page

BARRICK GOLDSTRIKE MINES, INC. (GOLDSTRIKE) NVMACT ANALYSIS FOR THE AUTOCLAVES..................................... 3

Introduction................................................................................................................... ................................................................ 3 Source Description ............................................................................................................. .......................................................... 3 Part I – Existing Similar Thermal Units........................................................................................ ............................................. 6

Mercury Controls

............................................................................................................................... ................6 Wet Scrubbers.................................................................................................................. ..............................6 Work Practices

............................................................................................................................... ...................8 Mercury Emissions

............................................................................................................................... .............8 Mercury Control Costs

............................................................................................................................... .....10 Non-Air Quality Health and Environmental Impacts and Energy Requirements ............................................11 Part II – Other Controls and/or Work Practices................................................................................. ..................................... 12

Other Mercury Control Options ......................................................................................................................12

Boliden Norzinc................................................................................................................ ...........................12 Selenium Scrubbers ............................................................................................................. ........................13 Wet Electrostatic Precipitators................................................................................................ .....................13 Activated Carb on Filters....................................................................................................... .......................13 Activated Carbon Injection..................................................................................................... .....................14 Selenium Filters............................................................................................................... ............................14 Condensers..................................................................................................................... ..............................15 Other Work Practices

............................................................................................................................... .......16 Part III - Proposed NvMACT ..................................................................................................... ............................................. 17

Mercury Controls and Work Practices ............................................................................................................17 Mercury Emissions

............................................................................................................................... ...........19 Mercury Control Costs

............................................................................................................................... .....19 Non-Air Quality Health and Environmental Impacts and Energy Requirements ............................................20 Appendix A - General Arrangement ............................................................................................... ............................................ 22 Appendix B - Piping and Instrumentation Diagrams............................................................................... .................................... 32 Appendix C - Process Flow Diagrams............................................................................................. ........................................... 36 Appendix D - Process Design Criteria........................................................................................... ............................................. 52

ENDNOTES....................................................................................................................... ............................................................. 69



### Tables
Table 3.1: Autoclave Stack Testing Mercury Emissions Summary.................................................................. ................................ 9
Table 3.2: Autoclave Sta ck Test Mercury Speciation ............................................................................ ........................................ 10 Table 3.3: Goldstrike Alkaline Source Test Mercury Emissions .................................................................. .................................. 19 Table 3.4: Estimated Capitol and Operating Costs fo r the New Autoclave Mercury Off-Gas Control System ......................... ..... 20



### Figures
Figure 3.1: Existing Autoclave Circuit Process Flow Diagram................................................................... ...................................... 4 Figure 3.2: Existing Autoclave Circuit Emission Controls ...................................................................... .......................................... 5 Figure 3.3: Rectangular Throat Venturi Scrubber............................................................................... ............................................. 7 Figure 3.4: Mercury Saturation Pressure Curve ................................................................................. ........................................... 15 Figure 3.5: Proposed Autoclave Circuit Emission Controls ...................................................................... ..................................... 18Appendix 3, Page 3 

# BARRICK GOLDSTRIKE MINES, INC. (GOLDSTRIKE) NVMACT ANALYSIS FOR THE AUTOCLAVES

Introduction

Barrick Goldstrike Mines Inc. (Goldstrike) operates six autoclaves which vent to four stacks. The
autoclaves are used to oxidize sulfide ore under pressure using steam and oxygen. Historically, Goldstrike has used acidic autoclaving to process the sulfide ore; however, due to the changing ore characteristics, Goldstrike plans to operate three autoclaves (Autoclaves 4 though 6) in an alkaline mode of operation in the future. Recent mercury stack te st data indicates that the mercury emissions from processing ore under alkaline conditions are higher th an the emissions from acidic autoclaving. (Testing was authorized by NDEP pursuant to NAC 445B.232.)

Per NAC 445B.3681.6, a Nevada Maximum Achievable Control Technology (NvMACT) analysis is required to be conducted for new or modified thermal units that emit mercury as a part of the application for a revision to a mercury operating permit to construct. The NvMACT analysis provided herein addresses all the requirements of NAC 445B.3681.6.


## Source Description

In the autoclave circuit, sulfide ore is oxidized (see Figure 3.1). Sulfid e ore slurry from the wet grinding mills is first thickened in thickener tanks. The slurry is then acidulated with sulfuric acid in acidulation tanks. Sulfide ore slurry from the acidulation tanks is pre-heated and then oxidized in the autoclaves with pressure, steam, and oxygen. Currently, the off- gas from each autoclave passes through a dedicated venturi scrubber before being released to the atmosphere (the exhaust from Autoclaves 2 and 3 and Autoclaves 5 and 6 are ducted together downstream of the venturi scrubbers for a total of four stacks) (see Figure 3.2). When the gas exits the ve nturi scrubber it is saturated with water.Appendix 3, Page 4 Figure 3.1: Existing Autoclave Circuit Process Flow Diagram

STEAM GENERATION

PLANT TO ATMOSPHERE SLURRY COOLER SURGE TANKS FLASH TANKS SLURRY COOLERS

STEAM AUTOCLAVES

AIR LIQUIDE OXYGEN PLANT O 2 S2.015 - S2.020 SPLASH CONDENSERS

COOLING TOWERS WATER ORE FROM WET GRINDING PROCESS

TO CIL TANKS SLAKED LIME LIME SLAKERS

HEAT PRE OXIDATION THICKENERS

TO ATMOSPHERE

WET SCRUBBERS TO RECLAIM WATER TANK

SULFURIC

ACID TANKS ACIDULATION TANKS

NEUTRALIZATION TANKS

FLOW OF GOLD LEGEND:

MINOR FLOW WATERAppendix 3, Page 5 Figure 3.2: Existing Autoclave Circuit Emission Controls

Autoclave #1

S2.015 Autoclave #1

Venturi Scrubber

Autoclave #3 S2.017 Autoclave #2

S2.016 Autoclave #2

Venturi Scrubber Autoclave #3 Venturi Scrubber To Atmosphere

(Stack #2) To Atmosphere

(Stack #1)

Autoclave #4 S2.018 Autoclave #4

Venturi Scrubber

Autoclave #6 S2.020 Autoclave #5

S2.019 Autoclave #5

Venturi Scrubber Autoclave #6 Venturi Scrubber To Atmosphere

(Stack #4) To Atmosphere

(Stack #3)Appendix 3, Page 6 

## NvMACT Analysis

Part I – Existing Similar Thermal Units
Part I of this NvMACT analysis provides a list of the similar existing thermal units used for precious metal mining and describes the controls and work practices used to reduce mercury emissions. All information required by NAC 445B.3681, as described below, is provided herein:

NAC 445B.3681 New or modified thermal unit that emit s mercury: Contents of required application.

6.(b) Sets forth a list of similar th ermal units that emit mercury which a re used for precious metal mining that
includes, without limitation:

(1) Any methods or technologies to control mercury emi ssions which are associated with the thermal units that emit mercury;

(2) The level of mercury emissions associated with ea ch method or technology to control mercury emissions from the thermal units that emit mercury;

(3) The design for each method or technology to cont rol mercury emissions from the thermal units that emit

mercury;
(4) Costs associated with reductions of mercury emissions as a result of each method or technology to control mercury emissions from the therm al units that emit mercury;

(5) Costs associated with energy for each method or technology to control mercury emissions from the thermal that emit mercury; and

(6) Consistent with section 112(d)(2) of the Act, an y nonair quality health an d environmental impacts and energy requirements for each method or technology to control mercury emissions from the thermal units that emit mercury.



### Mercury Controls
An examination of the Nevada Mercury Control Program (NMCP) Phase-2 Applications 1 showed that there is only one other precious metal mining facility in Nevada with an existing autoclave circuit. At both Goldstrike and Newmont Twin Creeks, the existi ng control for these thermal units is venturi wet
scrubbers.



### Wet Scrubbers
All of the existing autoclaves employ a venturi scrubbe r as an off-gas control. The venturi scrubbers are installed primarily to control particulate emissions. Wet scrubbers may control oxidized mercury, 2 as this form of mercury is soluble in the scrubber water, and elemental mercury, if the scrubber exhaust temperature is decreased to below th e mercury saturation temperature.

Venturi wet scrubbers control particulates, including particulate mercury, through impaction, diffusion, interception, and/or adsorption of the pollutant onto droplets of liquid. 3 Venturi scrubbers use a converging then diverging flow channel such that th e area of the channel decreases then increases alongAppendix 3, Page 7 the length of the channel. The narrowest area is called the throat. As the exhaust gas enters the venturi scrubber, the decrease in area causes the gas velocity and turbulence to increase. The scrubbing water is injected either slightly upstream of or directly into the throat section. As the scrubbing solution is injected, the turbulence in the throat causes it to atomize, which improves gas-liquid contact. 3 After passing through the throat, the gas-liquid mixture de celerates and causes additional particle-droplet impacts and agglomeration of the droplets. Before the gas exits the scrubber, the liquid droplets are separated from the gas in an entrainment section. 3

As the gas passes through the venturi scrubber, there is a drop in pressure. For venturi scrubbers in general, the greater the pressure drop, the higher the particulate control efficiency. However, for autoclaves, the temperature and pressure of the autocl ave itself is maintained by limiting the release of steam and off-gas. Therefore, when the gas flow passing through the scrubber is low, there is low pressure drop across the scrubber.

The liquid to gas ratio also affects venturi scrubber efficiency. There must be sufficient liquid injected into the scrubber to allow for coverage over the throat area and to create sufficient collection targets. After an optimal point, adding excess liquid to a scrubber does not increase the particulate control efficiency. The liquid to gas ratio for wet scrubbers ty pically ranges from 4 to 20 gallons per 1,000 actual cubic feet (gal/kacf). 4 A diagram of a typical venturi scrubbe r is provided as Figure 3.2.

Figure 3.3: Rectangular Throat Venturi Scrubber 5Appendix 3, Page 8 

### Work Practices
Work practices associated with autoclaves and venturi scrubbers include monitoring of the autoclave throughput and monitoring the venturi scrubber flow rate and pressure drop. Autoclaves operate under pressure and are ducted such that all the exhaust is vented through the venturi scrubber. Total exhaust flow, and emissions, are limited by limiting the release of steam and off-gas to the venturi scrubber as previously discussed.



### Mercury Emissions
The actual mercury emissions from the autoclaves at precious metal mining facilities in Nevada were
obtained from stack tests. 6 Table 3.1 provides the pound-per-hour (lb/hr) emission rate as well as the mercury concentration data for autoclaves.

### Table 3.1: Autoclave Stack Testing Mercury Emissions Summary

Emissions Hg Conc. Mine Unit Control lb/hr gr/dscf Test Info a

Twin Creeks Mine Phase I & II Autoclave Venturi Scrubber 1.16E-01 1.12E-03 10/21/1997

Autoclave Venturi Scrubber 5.77E-02 1.29E-03 6/22/1998

Autoclave Venturi Scrubber 1.53E-02 6.57E-04 1/27/2001

Phase I Autoclave Venturi Scrubber 8.25E-02 1.27E-03 10/4/2005

Phase I Autoclave Venturi Scrubber 3.87E-02 5.81E-04 10/4/2005

Phase I Autoclave Venturi Scrubber 5.26E-02 9.68E-04 6/13/2007

Phase I Autoclave Venturi Scrubber 4.34E-02 8.37E-04 6/13/2007

Phase I Autoclave Venturi Scrubber 6.55E-02 1.02E-03 6/15/2007

Phase I Autoclave Venturi Scrubber 6.62E-02 1.15E-03 6/15/2007

Phase II Autoclave Venturi Scrubber 3.30E-02 6.06E-04 6/16/2007

Phase II Autoclave Venturi Scrubber 2.54E-02 4.23E-04 6/16/2007

Phase I Autoclave Venturi Scrubber 8.47E-02 1.72E-03 8/18/2008

Phase II Autoclave Venturi Scrubber 3.30E-02 6.73E-04 8/21/2008

Barrick Goldstrike Mine Autoclave 1 Venturi Scrubber 6.63E-03 3.05E-04 8/28/1990

Autoclave 1 Venturi Scrubber 2.30E-03 1.40E-04 7/10/1991

Autoclave 2 & 3 Venturi Scrubber 1.23E-03 2.01E-05 9/17/1992

Autoclave 4 Venturi Scrubber 1.13E-03 1.37E-04 5/2/2006

Autoclave 4 Venturi Scrubber 2.87E-03 2.63E-04 5/3/2006

Autoclave 4 Venturi Scrubber 1.07E-03 6.20E-05 7/23/2009

Autoclave 5 & 6 Venturi Scrubber 1.17E-03 3.65E-05 7/24/2009

Autoclave 2 & 3 Venturi Scrubber 8.63E-04 2.55E-05 7/28/2009

Autoclave 1 Venturi Scrubber 7.13E-04 5.92E-05 7/29/2009

a Obtained from the Nevada Mercury Control Program (NMCP) Mercury Emission Management System (MEMS) database.

Appendix 3, Page 8Appendix 3, Page 10 Ontario Hydro Method (OHM) stack te st reports provided mercury specia tion data for the autoclaves at Goldstrike. Flue-gas Absorbent Mercury Speciation (FAMS) test data was av ailable for Newmont Twin Creeks. For all these autoclaves, the test data is repr esentative of an autoclave controlled by a venturi wet scrubber. The mercury speciation data is provided in Table 3.2.

Table 3.2: Autoclave Stack Test Mercury Speciation 7,8,9

Mine Source Controls Elemental Mercury Oxidized Mercury Particulate Mercury

Goldstrike Autoclave 1 Venturi Scrubber 92.8% 5.1% 2.2%

Autoclave 2 & 3 Venturi Scrubber 69.8% 23.3% 6.9%

Autoclave 4 Venturi Scrubber 78.1% 8.3% 13.6%

Autoclave 5 & 6 Venturi Scrubber 66.4% 26.8% 6.7%

Twin Creeks Phase I Autoclave Venturi Scrubber 97.9% 1.6% 0.5%

Average 81.0% 13.0% 6.0%

As shown by Table 3.2, a majority of the emissions from the existing autoclaves is in the form of elemental mercury (81 percent on average). A smalle r percentage of the emissions is oxidized mercury (13 percent on average) and the remaining smallest percentage of emissions is particulate mercury (6 percent on average).



### Mercury Control Costs
The Phase-2 Applications submitted by precious metal mining facilities in Nevada provided estimated total installed costs for the existing mercury cont rols for autoclaves. According to Newmont Twin Creek’s Phase-2 Application, the total installed costs of their venturi scrubbers for Autoclaves 1 and 2 were $347,000 and $364,000 in 2007 dollars, respectively. The annual operating and maintenance costs were not provided.

Annual utility costs represent the cost of the energy required for each of the control technologies. Venturi scrubbers require energy for the pumps that circulate scrubber solution through the system. Due to the fact that autoclaves are pressurized, the venturi scrubbers do not require a fan to push the exhaust through the scrubbers. According to the EPA Control Cost Manual, for a typical venturi scrubber with a liquid flow rate of 10 gallons per minute (gpm), a pressure of 20 pounds per square inch gauge (psig), and a pressure drop of 15 inches of water gauge (in. H 2 O g), the water pump energy requirement is estimated to be 0.233 horsepower per thousa nd cubic feet per minute (hp/1,000 cfm). 3 Assuming 24 hours per day and 7 days per week operation and an electricity cost of 9 cents per kilowatt-hour (kW-hr), the annual utility cost of a venturi scrubber with a gas flow rate of 30,000 acfm is approximately $4,000.Appendix 3, Page 11 

### Non-Air Quality Health and Environmental Impacts and Energy Requirements
For autoclaves, the typical venturi scrubber installati on uses process water as the scrubbing solution. This results in non-air quality health and environm ental impacts from the discharge of the scrubbing
solution. Venturi scrubbers also cause non-air qu ality health and environmental impacts from the increased energy consumption due to the scrubber water pump. For a typi cal venturi scrubber with a gas flow rate of 30,000 acfm, the energy requir ement is estimated at 46,000 kW-hr/yr.Appendix 3, Page 12 

### Part II – Other Controls and/or Work Practices
This part of the NvMACT analysis examines other control options and/or work practices that are not currently employed on existing autoclaves. (See Part I.)



### Other Mercury Control Options
In addition to the mercury technologies employed at existing autoclaves at precious metal mining facilities in Nevada, other mercury control options for autoclaves have been examined. These control technologies include:

• Boliden Norzinc,

• selenium scrubbers,

• wet electrostatic precipitators (ESPs),

• activated carbon filters

• activated carbon injection,

• selenium filters, and

• condensers.



### Boliden Norzinc
In the Boliden Norzinc process, a mercuric chloride solution reacts with the elemental mercury in the offgas to form a mercurous chloride precipitate, known as calomel, which is settled and recovered. This reaction occurs in a packed column. Once the solid is removed, the wash solution can be recirculated. A portion of the precipitate can be used to regenerate the mercuric chloride solution using chlorine gas. 10 The rest of the calomel is sent off site for reclamation. The Boliden Norzinc process uses the following

reaction:

HgCl 2(sol’n) + Hg (gas) → 2HgCl (solid)

The Boliden Norzinc process is installed at Goldstrike’s roasters, which have a gas stream with high mercury content. The Boliden Norzinc process can achi eve outlet concentrations of 0.03 to 0.05 mg/Nm 3

. Because these outlet concentrations are similar to th e outlet mercury concentrat ions from the autoclaves, the Boliden Norzinc process would not be expected to provide significant additional mercury control.

The ideal operating temperature for the Boliden Norzinc process is 104  ̊ F. As shown in Table 3.1, the average outlet temperature for autoclaves is approximately 190  ̊ F, and would therefore require gas stream cooling before control by the Boliden Norzinc process. The cooling of the saturated gas stream would require significant energy input, as energy is re quired to both condense the water and cool the gas stream. At the Goldstrike autoclaves, over 100 MMBtu/hr would be required to cool the combined gas

stream to 100  ̊ F.Appendix 3, Page 13 The Boliden Norzinc process has not been applied to an existing autoclave at precious metal mining facilities in Nevada. Thus, there is no basis for assessing its performance in such an application given the dissimilarities between the autoclaving process (and its characteristic emission stream) and those units/emission streams where Boliden Norzinc has been applied. In addition, this technology requires a significant capital investment and results in increased wastewater (process water containing chloride ions) and solid waste (calomel).



### Selenium Scrubbers
Selenium scrubbers use selenium or a selenium comp ound within a scrubber to react with the elemental mercury in the off-gas to form mercuric selenide (HgSe). Mercuric selenide has a lower vapor pressure than other common mercury compounds which allows fo r mercury capture. The mercuric selenide is removed in a sludge separation circuit, which requires a thickener and HgSe reclamation. Sulfuric acid, at concentrations between 10 and 60 percent, is used as the wash solution for the process.

Selenium scrubbers are appropriate for gas stre ams with high mercury loading. The outlet concentrations from this process are typically higher than the concentrations achieved from the Boliden Norzinc process discussed above. Selenium scrubb ers are not widely used due to the low removal efficiencies as well as the expensive reagent and reclamation requirements.



### Wet Electrostatic Precipitators
Wet electrostatic precipitators (ESPs) use electrostati c charges to move particulates from a gas stream
onto a collection surface. The electric field is crea ted through electrodes that are maintained at a high voltage. Wash water is used to clean th e particulates from the collection plates. 10 Wet ESPs are designed for saturated gas streams and have a maximum operating temperature of 170 to 190  ̊ F. Wet ESPs will collect dust, fumes, aerosol mist, and liquid droplets from a gas stream; however they do not provide any effective control of oxidized or elemental mercury. 10 Therefore, gaseous elemental and oxidized mercury, which is a majority of autoclave mercury emissions, will not be controlled. The particulate mercury is already controlled by the existing venturi scrubber.



### Activated Carbon Filters
Carbon adsorption filters use activated carbon pa rticles to adsorb mercury from the gas stream. Adsorption occurs when gas molecules are passed thro ugh a bed of solid particles, and the gas molecules migrate from the gas stream to the surface of the solids where they are held by physical attraction. 11 Carbon impregnated with elemental sulfur increases the adsorption efficiency of the beds due to the mercury reacting with the sulfur to form mercury sulfide (HgS). Mercury sulfide has a lower vapor pressure than elemental mercury and is more readily removed. 10

Activated carbon beds control all ty pes of mercury: particulate boun d, oxidized, and elemental. The mercury in the gas stream is adsorbed to the carbon and collected as carbon loaded with mercury. Once the carbon reaches adsorptive capacity, it is replaced, and the spent carbon is reclaimed. Monitoring of the carbon bed mercury content is performed to ensu re that the mercury loading does not exceed theAppendix 3, Page 14 value recommended by the manufacturer. For activate d carbon beds, the typical carbon loading capacity is approximately 20 percent (or more) mercury by weight. 12,13 Carbon mercury loading can be monitored directly, or the mercury concentration in the exhaust at the outlet of the carbon bed can be monitored to
ensure the effectiveness of the carbon adsorber.

Some factors that can affect carbon bed adsorption efficiency include residence time of the gas in the carbon bed, bed temperature, and carbon particle si ze. Longer residence times, lower bed temperature, and smaller carbon particle sizes increase the mercury removal efficiency of the carbon bed. 10 The gas flow rate, bed size, and mass of the carbon in the bed influence the residence time of the gas in the carbon bed. A lower flow rate and larger carbon bed wi th more carbon mass increases the residence time. 10

The possibility of controlling the autoclaves at Go ldstrike with carbon adsorption technology was investigated. The exhaust streams from the existing Venturi scrubbers would have to be cooled and have the water removed before entering a carbon bed. Exce ssive water collection in a carbon filter will reduce control efficiency. Water can enter the pore structur e of the carbon and block active adsorption sites, reducing the surface area available for mercury collection. The application of activated carbon technology for controlling mercury emissions from the au toclaves when operating in an alkaline mode is
discussed further below in Part III.



### Activated Carbon Injection
Activated carbon injection is similar to activated carbon filters in that activated carbon particles are used to adsorb mercury from the gas stream. With carbon injection, the carbon particles are injected directly into the gas stream where they adsorb mercury and ar e then collected in downstream particulate controls such as baghouses, wet scrubbers, or wet ESPs. As wi th activated carbon filters, the control effectiveness of activated carbon injection will be limited if water enters the activated adsorption sites. There is no precedent for using the carbon injection technology on gas streams with high moisture content as in the case of the Goldstrike autoclaves. In addition, the control efficiency for carbon injection is typically lower than for carbon beds. Therefore, the appropriate application of the activated carbon technology for autoclaves is a carbon adsorption filter.



### Selenium Filters

Selenium filters are similar to selenium scrubbers in that they use selenium to react with the elemental mercury in the gas stream to form mercuric seleni de. Selenium filters use a selenium impregnated porous carrier structure which is housed in a cylindrical tower. The selenium filter’s maximum operating temperature is approximately 250  ̊ F. The filters require a dry gas stream because water will degrade the filter media. This provides a significant limitation to its application for the Goldstrike autoclaves. The typical filter carrying capacity is between 10 and 15 percent mercury by weight.

There are only a few installations of selenium filters in the world, primarily in Sweden, and there is no operating data from these applications. Selenium fi lters are expensive to produce and to regenerate.Appendix 3, Page 15 There is no basis to believe that selenium filters would provide a better alternative than activated carbon. In addition, there is some concern that th e filters cause selenium air emissions.



### Condensers
Condensers control mercury by cooling a gas stream and causing the elemental mercury to condense. In order for condensation to occur with a drop in te mperature, the gas stream must be saturated with mercury vapor. Mercury saturation is determined by the mercury saturation pressure curve as shown
below.

Figure 3.4: Mercury Saturation Pressure Curve 14

Based on recent stack tests of alka line autoclaving at Goldstrike (authorized by NDEP pursuant to NAC 445B.232), the concentration of mercury in the exhaust stream ranged from 1.14x10 -3 to 3.00x10 -3 gr/dscf. This concentration is below the mercury saturation co ncentration even if the gas stream is cooled to 70  ̊ F. (The saturated mercury concentration at 70  ̊ F is approximately 6.8x10 -3 gr/dscf. 14 ) However, at the maximum mercury concentration (6.8x10 -3 gr/dscf), the exhaust stream would be close to saturated if it
was cooled to 70  ̊ F and therefore, mercury condensation may be an effective control technology for the autoclaves at Goldstrike, when operating in the alkaline mode. 0.000 0.005 0.010 0.015 0.020 0.025 0.030

30 50 70 90 110 130 150 170 190 Temperature (F)Vapor Pressure (kPa)Appendix 3, Page 16 

### Other Work Practices
There are no process changes or material substitutions that can be instituted to reduce mercury emissions from autoclaves. (All work practice options are di scussed in Part I). Mercury is present in the ore currently being mined and will be pr esent during the mine life.Appendix 3, Page 17 

## Part III - Proposed NvMACT

Per NAC 445B.3681.6(a), the applicant must propose “ standards, methods of control or other limitations to be applied to the thermal unit for the reduction of mercury emissions that the applicant deems sufficient for the Director to determine to be NvMACT for the thermal unit that emits mercury .” Therefore, the NvMACT proposed in this part follows the criteria that are required by the Director pursuant to NAC 445B.3683.2(b). All items considered in this NvMACT analysis are checked in the criteria list provided
below:

NAC 445B.3683 Review of an d action on application for new or modi fied thermal unit that emits mercury.

2.(b) Make a determination of NvMACT for the thermal unit that emits mercury in which the Director shall consider the following for each thermal unit that emits mercury:
(1) The maximum degree of reduction of mercury emi ssions that is achievable for the thermal unit after considering:
(I) The cost of achieving such a reduction; and
(II) Consistent with section 112(d)(2) of the Act, any nonair quality health and environmental impacts and energy requirements for each method or technology to control mercury emissions from the thermal unit that emits mercury to implement the NvMACT.

(2) The measures that reduce the volume or eliminate m ercury emissions through proc ess changes, substitution of materials or any other modifications.
(3) The enclosure of systems or pr ocesses to eliminate mercury emissions.
(4) The collection, capture or treatment of mercury emissions.
(5) The design, equipment, work practice or operation al standards of the thermal unit that emits mercury, including, without limitation, the requirements for trai ning and certification of operators of the thermal unit that emits mercury.
(6) The differences in the age, remaini ng operating life and configurations of similar thermal units that emit mercury. The Director may also consider the differences in the concentration of mercury in the ore, size and any other relevant factors of the simila r thermal units that emit mercury.



### Mercury Controls and Work Practices
Based on the existing control technologies and work practices described in Part I and the additional control technology options described in Part II, Gold strike proposes that adding a secondary venturi scrubber, a scrubber mist eliminator, a gas cooling towe r, a condenser, a wet gas separator, and a carbon filter downstream of the existing Autoclave 4 through 6 venturi scrubbers and the following work practices are NvMACT. These work practices include:

• monitoring the autoclave throughput,

• maintaining the flow rate and pressure drop wi thin the manufacturer’s recommended operating range for all venturi scrubbers,Appendix 3, Page 18 • maintaining the flow rate and pressure drop of the cooling tower within the manufacturer’s recommended operating range,

• maintaining the outlet temperature of the cond enser within the manufacturer’s recommended operating range,

• collecting condensed mercury from th e condenser as a co-product, and

• replacing the carbon in the new carbon filter prior to exceeding the maximum loading as recommended by the manufacturer.

A flow diagram of the proposed NvMACT control sy stem is provided in Figure 3.5. Please see Appendices A through D for the general arrangemen t, piping and instrument ation diagrams, process flow diagrams, and process design criteria.

Figure 3.5: Proposed Autoclave Circuit Emission Controls

The Goldstrike Autoclaves can process a total of 1,130 tons of ore per hour (130 tons/hr for Autoclave 1 and 200 tons/hr each for Autoclaves 2 - 6) and can operate 8,760 hours per year, each. Autoclave #4

S2.018 Secondary

Venturi Scrubber

Scrubber Mist Eliminator Gas Cooling Tower Condenser Wet Gas Separator Carbon Filter Booster Fan

Autoclave #4

Primary Venturi Scrubber

Autoclave #6 S2.020 Autoclave #5

S2.019 Autoclave #5

Primary Venturi Scrubber Autoclave #6 Primary Venturi Scrubber To Atmosphere (Stack #3) Autoclave #1

S2.015 Autoclave #1

Venturi Scrubber

Autoclave #3 S2.017 Autoclave #2

S2.016 Autoclave #2

Venturi Scrubber Autoclave #3 Venturi Scrubber To Atmosphere

(Stack #2) To Atmosphere

(Stack #1)Appendix 3, Page 19 The engineering for the new autoclave mercury off-gas control project has not been completed. However, preliminary design specifications and cost data have been obtained from Aker Solutions. Based on this preliminary data, the carbon adsorption filter will co ntain 40,000 pounds of activated sulfur-impregnated carbon. The new controls are designed so that the exha ust flow rate through the carbon filters is expected to be approximately 15,500 acfm and the residence time to be approximately 4 seconds. For activated carbon filters, the typical carbon loading capacity is approximately 20 percent (or more) mercury by weight.

A new venturi scrubber, scrubber mist eliminator, gas cooling tower, condenser, and wet gas separator will be installed upstream of the carbon filter to cool the gas stream and remove mercury and condensate from the gas stream.



### Mercury Emissions
The proposed NvMACT performance standard for the autoclave 4 through 6 common stack is 7.8 x 10 -5 grains per dry standard cubic foot (gr/dscf). This standard was estimated based on the recent mercury source tests performed in March 2010 at the Goldst rike autoclaves while processing ore under alkaline conditions. (Testing was authorized by NDEP purs uant to NAC 445B.232.) The concentration was calculated from the maximum average concentration (two run avg.) of the aforementioned Goldstrike alkaline source tests (provided in Table 3.3) plus three standard deviations, targeting 98% control. This calculation method accounts for limited test data as well as stack testing and operational variability.

Table 3.3: Goldstrike Alkaline Source Test Mercury Emissions

Run #1 Run #2 Run #1 Run #2 Run #1 Run #2 Run #1 Run #2 Run #1 Run #2

Total Mercury (gr/dscf) 2.80 x 10 -3 2.37 x 10 -3 2.91 x 10 -3 2.66 x 10 -3 2.87 x 10 -3 2.73 x 10 -3 3.00 x 10 -3 1.14 x 10 -3 2.16 x 10 -3 1.99 x 10 -3

Two Run

Avg. (gr/dscf) 2.59 x 10 -3 2.79 x 10 -3 2.80 x 10 -3 2.07 x 10 -3 2.08 x 10 -3



### Mercury Control Costs
Estimated capitol and operating costs for the new auto clave mercury off-gas control system are provided
in Table 3.4.Appendix 3, Page 20 Table 3.4: Estimated Capitol and Operating Costs for the New Autoclave Mercury Off-Gas Control System

Item Description Cost Basis Capitol Costs Engineering Costs $ 3,506,350 2010 estimate Material Costs $ 13,219,950 2010 estimate Labor Costs $ 11,583,070 2010 estimate Barrick Project Support $ 977,500 2010 estimate Total Capitol Costs $ 29,286,870 2010 estimate
Operating Costs Operating Labor (4 operators at $90,000/yr) $ 360,000 Per year Maintenance Labor (1 maintenance at $90,000/yr) $ 90,000 Per year Maintenance Supplies $ 533,774 Per year Utilities ($0.08/kW-hr) $ 911,129 Per year Consumables (replacement carbon, reagents and flocculants, cooling tower treatment chemical) $ 251,550 Per year

Total Operating Costs $ 2,146,453 Per year

The proposed control technologies and work practi ces require energy for the venturi scrubber variable throat, venturi scrubber/scrubber mi st eliminator pump, gas cooling tower pump, condensate pump, effluent pump, refrigeration unit, booster fan, cooling tower fans, cooling tower pumps, humidity control heater, and transformer. The maximum annual esti mate of total energy required for these units,assuming 24 hours per day and 7 days per week operation is 11,389,107 kilowatt-hours per year (kWhr/yr). As shown in Table 3.5, assuming an electricit y cost of 8 cents per kW-hr, the total energy cost is $911,129 per year.

Before the sulfur-impregnated carbon in the carbon filter reaches the maximum carbon loading capacity (approximately 20 percent mercury by weight), it wi ll need to be replaced. The new carbon and each carbon replacement will cost approximately $82,800 per replacement. In addition, disposal costs of spent carbon are approximately $2.50 per pound of carbon 15 or $100,000 per replacement.

The proposed new control technologies are expected to last the remaining life of the mine.



### Non-Air Quality Health and Environmental Impacts and Energy Requirements
Non-air quality health, environmental, and energy impacts are associated with the collection of particulates and mercury condensates from the vent uri scrubber, gas cooling tower, and condenser. Furthermore, the shipping and reclamation of th e spent carbon and elemental mercury has non-air quality health, environmental, and energy impacts. Du e to additional controls on this system, overall emissions of regulate d pollutants (PM, SO 2 , H 2 S) are expected to decrease.Appendix 3, Page 21 In addition, better control of mercury emissions from these sources decreases the opportunity of mercury exposure for Goldstrike personnel and contract ors performing work in the autoclave areas.

The cooling towers also have non-air quality he alth, environmental, and energy impacts from the
recirculation of water. To counteract the non-air quality health and environmental impacts associated, chemicals are added to the water to prevent the growth of harmful bacteria. Additionally, because of the pumping requirements for the recirculation of water through the cooling towers energy impacts are also associated with this aspect of the project.

Furthermore, condensation of the steam from the au toclaves which is currently being evaporated will
increase Goldstrike’s water balance. All water co ndensed must be treated and reused to offset the additional water input.

Goldstrike’s energy requirements will increase as a resu lt of this project. Operation of the new autoclave off-gas mercury control system wi ll require 11,389,107 kW-hr/yr.

Installation of these controls allows for an extended life of the autoclave facility, which in turn maintains job availability for Goldstrike personnel. Without these controls, the autoclaves would be shut down at
the end of 2010.Appendix 3, Page 22 

# Appendix A

GENERAL ARRANGEMENT

## Copyrighted page/s removed. Copyrighted ma terial is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder.

Contact the EPA Docket Center’s P ublic Reading Room to view or receive a copy of this document.

Requests for copies may be made as follows:

In person/writing: Environmental Protection Agency, Docket Center 1301 Constitution Ave NW, 2822T, Room 3334 Washington, DC. 20004

Telephone: 202-566-1744

Fax: 202-566- 9744

Email: docket-customerservice@epa.govAppendix 3, Page 32 

# Appendix B

PIPING AND INSTRUMENTATION DIAGRAMS

## Copyrighted page/s removed. Copyrighted ma terial is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder.

Contact the EPA Docket Center’s P ublic Reading Room to view or receive a copy of this document.

Requests for copies may be made as follows:

In person/writing: Environmental Protection Agency, Docket Center 1301 Constitution Ave NW, 2822T, Room 3334 Washington, DC. 20004

Telephone: 202-566-1744

Fax: 202-566- 9744

Email: docket-customerservice@epa.govAppendix 3, Page 36 

# Appendix C

PROCESS FLOW DIAGRAMS

## Copyrighted page/s removed. Copyrighted ma terial is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder.

Contact the EPA Docket Center’s P ublic Reading Room to view or receive a copy of this document.

Requests for copies may be made as follows:

In person/writing: Environmental Protection Agency, Docket Center 1301 Constitution Ave NW, 2822T, Room 3334 Washington, DC. 20004

Telephone: 202-566-1744

Fax: 202-566- 9744

Email: docket-customerservice@epa.govAppendix 3, Page 52 

# Appendix D

PROCESS DESIGN CRITERIA

## Copyrighted page/s removed. Copyrighted ma terial is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder.

Contact the EPA Docket Center’s P ublic Reading Room to view or receive a copy of this document.

Requests for copies may be made as follows:

In person/writing: Environmental Protection Agency, Docket Center 1301 Constitution Ave NW, 2822T, Room 3334 Washington, DC. 20004

Telephone: 202-566-1744

Fax: 202-566- 9744

Email: docket-customerservice@epa.govAppendix 3, Page 59 

# ENDNOTES

1 Nevada Division of Environmental Protection, Bureau of Air Quality Planning. Nevada Mercury Control Program (NMCP) - NvMACT Cl earinghouse. Phase-2 Applications . 2008. http://ndep.nv.gov/BAQP /hg/clearinghouse.html

2 Rong Yan et al. “Bench-scale experimental evaluation of carbon performance on mercury vapour adsorption.” Fuel . Vol. 83, No. 17-18, 2004, p. 2402.

3 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Control Cost Manual , 6 th ed. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. 2003. Section 6, Chapter 2 – Wet Scrubbers for Particulate Matter.

4 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Training Institute (APTI) SI:412C Scrubber Systems Operation Review . Lesson 2, 1998.

5 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Training Institute (APTI)SI:412C Scrubber Systems Operation Review . 1998. Lesson 3.

6 Nevada Division of Environmental Protection, Bureau of Air Quality Planning. Nevada Mercury Control Program (NMCP) - NvMACT Clearinghouse. Mercury Emissions Management System (MEMS) . 2010. http://www.ndep.nv.gov/baqp/search

7 Nevada Division of Environmental Protection, Bureau of Air Pollution Control. Precious Metals Mining Mercury Air Emissions Questionnaires . 2006.

8 2006 OHM Test Data for Tier-1 Units . Nevada Mercury Control Program (NMCP) Data Site. http://ndep.nv.gov/bapc/mercury/

.

9 TRC Environmental Corp. Final Report - Emissions Compliance Demonstration for Systems 18, 19, 61, and 66 (Class I Operating Permit No. AP1041-0739.01) - September 2007 . September 2, 2007.

10 Booz Allen & Hamilton Inc. Report prepared for U.S. EPA Region 9. Mercury Mass Balance and Emission Factor Estimates for Gold Ore Processing Facilities (Draft) , U.S. EPA Region 9. January 14, 2001.

11 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Control Cost Manual , 6 th ed. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. 2002. Section 3.1, Chapter 1 – Carbon Adsorbers.

12 Scotia International of Nevada, Inc. Product Bulletin COL-IS 60 Coal Based Activated Carbon Impregnated with Sulfur

.

13 Michael G. Klett, Russell C. Maxwell, and Mich ael D. Rutkowski. Parsons Infrastructure and Technology Group Inc. Report prepared for the Un ited States Department of Energy National Energy Technology Laboratory. The Cost of Mercury Removal in an IGCC Plant Final Report . September 2002.Appendix 3, Page 60 14 Taylor and Francis Group. CRC Handbook of Chemistry and Physics , 86 th Ed. New York. 2005, p. 6-126.

15 Kemp, Joe. Environmental Engineer, Barrick Gold strike Mines, Inc. [Communication with E. Steen, Air Sciences Inc.]. October 1, 2007.Appendix 4, Page 1 

# Appendix 4

Request for de minimis Emissions Determination

Thermal Mercury Emitting UnitAppendix 5, Page 1 

# Appendix 5

APPLICATION CERTIFICATION

The responsible official must sign and date th e application certification found in Appendix 5. If the application is signed by a person other than the responsible official, as defined in NAC 445B.156, the application will be returned as incomplete.

Note: According to NAC 445B.156, Responsible Official means: 1. For a corporation: (a) A president; (b) A vice president in charge of a principal business function; (c) A secretary; (d) A treasurer; or (e) An authorized representative of such a pe rson who is responsible fo r the overall operation of the facility and who is designated in writing by the officer of the corporation and approved in advance by the director. 2. For a partnership or sole proprietorship: a general partner or the proprietor, respectively. 3. For a municipality or a state, federal or other pub lic agency: a ranking elected official or a principal executive officer, including, for a federal agency, a chief executive officer who has responsibility for the overall operations of a principal geographic unit of the agency. 4. For an affected source: the designated representa tive or his alternate, as defined in 42 U.S. C. § 7651 a (26).

# Nevada Mercury Control Program Operating Permit to Construct

Autoclaves 1 through 3

P REPARED FOR 

## : B

ARRICK 

## G OLDSTRIKE 

## M INES 

## I NC



## .

P REPARED BY 

## : A IR 

## S CIENCES 

## I NC



## .

P ROJECT N O

. 59-43-80 A UGUST 2010Page 1 

## Table of Contents

General Information .......................................................................................................... . Page 2

APPLICATION

Mercury Operating Permit to Construct Application Cover Page ...................................... Page 3 General Company Information .......................................................................................... Page 4 -General Company Information Form and Application Information (4 Pages)

Additional Forms

Mercury Unit Application Form ................................................................................ Appendix 1
System 66A, TU4.013, Autoclave Circuit 1, Au toclave #1 ........................................................................ ........ 3 System 66B, TU4.014-TU4.015, Autoclave Circuit 2, Autocl aves #2 & #3 ...................................................... 8



### Monitoring/Testing Plan ............................................................................................ Appendix 2 Nevada MACT (NvMACT) Analysis ........................................................................ Appendix 3

De minimis emissions Re quest .................................................................................. Appendix 4 Application Certification ........................................................................................... Appendi x 5Page 2 

### State of Nevada Division of Environmental Protection Bureau of Air Pollution Control



# APPLICATION FOR MERCURY OPERATING PE RMIT TO CONSTRUCT

Please return to: Nevada Divisi on of Environmental Protection Bureau of Air Pollution Control, Permitting Branch 901 South Stewart Street Carson City, Nevada 89701-5249 (775) 687-9350 FAX (775) 687-6396



## General Information

 This application is available from the Bureau of Air Pollution Control in a Microsoft Word file, or on the

internet at http://www.ndep.nv.gov/bapc. All information required in the application may be computer generated and submitted to the Bureau on compact disk(s) or DVD(s). In addition, one printed copy must be submitted.

 All information required by the “General Company Information” and by the relevant forms in the Appendices

must be completed.

 The application filing fee required by NAC 445B.3689 must be submitted with the completed application.

Checks must be made payable to: “Nevada State Treasurer, Enviro nmental Protection”.

 This application packet shall be used for Tier 1, Tier 2 thermal units that emit mercury, for construction of

new thermal units that emit mercury, for de minimis designation and construction and installation projects for thermal units that emit mercury at new and existing stationary sources.

 An application for a mercury operating permit to constr uct must be signed by a responsible official, as

defined in Section NAC 445B.297.1. The certification/signature page is contained in Appendix 5.

 All items in the application must be addressed. If an item does not apply, please indicate so with “N/A” or

similar notation in the appropriate blank. All other information must be provided. Incomplete applications will be returned to the responsible official.Page 3 

# Application for Mercury Air Quality

Operating Permit to ConstructPage 4 GENERAL COMPANY INFORMATION

All applicants shall complete each item or explain in the sp ace provided why no information is needed. Please specify "N/A" (Not Applicable) if necessary. The application will be returned to the applicant if it is deemed incomplete.

1. COMPANY NAME AND ADDRESS THAT ARE TO APPEAR ON THE OPERATING PERMIT [NAC 445B.3671.1 and NAC 445B.3681.1]:

Barrick Goldstrike Mines Inc. (Name)

P.O. Box 29 (Address)

Elko NV 89803 (City) (State) (Zip Code)

2. Owner's Name and Address [NAC 445B.295.1]:

Barrick Gold Corporation (Name)

BCE Place, Canada Trust Tower, Suite 3700, 161 Bay Street, P.O. Box 212 (Address)

Toronto Ontario M5J2S1 (City) (State) (Zip Code)

3. Source Name and Mailing Address, if differen t from #1 [NAC 445B.3671.1 and NAC 445B.3681.1]:

Same as #1 (Name)

(Address)

(City) (State) (Zip Code)

4. Physical Location of Stationary Source [NAC 445B.3671.2 and NAC 445B.3681.7]: (if no physical address, describe location, e.g., 4 miles south of I-80 at xx Interchange)

27 miles north of Carlin, off State Route 766

Township(s) * Range(s) * Section(s) * * Sections 1 through 4, T35N, R49E ; Sections 12 through 15, 21 through 28, and 33 through 36, T36N, R49E; Sections 7 through 9, 16 through 21, and 28 through 32, T36N, R50E, MDB&M (HA 61) 5. Responsible Official Name, T itle and Address [NAC 445B.295.1]:

Joseph Giraudo Environmental Manager (Name) (Title)

Same as #1 (Address)

(City) (State) (Zip Code)

(775) 778 - 8140 (775) 778 - 8262 jgiraudo@barrick.com (Telephone #) (FAX #) (E-mail address)Page 5 GENERAL COMPANY INFORMATION (CONTINUED)

6. Plant Manager or Other Appropriate C ontact [NAC 445B.3671.1 and NAC 445B.3681.1]:

Carly Keeney Environmental Engineer (Name) (Title)

Same as #1 (Address)

(City) (State) (Zip Code)

(775) 778 - 8157 (775) 778 - 8262 ckeeney@barrick.com (Telephone #) (FAX #) (E-mail address)

7. If records required under the operating permit will be kept at a location other than the source, specify that location [NAC 445B.3671.5 and NAC 445B.3681].

N/A. Records will be kept on site. (Name)

(Address)

(City) (State) (Zip Co de)Page 6 APPLICATION INFORMATION

8. This application is submitted for (please check appropriate box below):


### Phase 1 Application

Tier 1 Unit(s) – Please provide the following:

a. An identification and description of any equipment for control of mercury emissions from all existing thermal units that emit mercury, including any presumptive NvMACT controls. In addition to the identification and description, please complete Section 5 of the Mercury Unit application form in Appendix 1. A separate Mercury Unit application form is required for each thermal unit that emits mercury. [NAC 445B.3673.1] b. A proposed monitoring plan for each therma l unit that emits mercury consistent with the requirements of NAC 445B.3673.2(a). Include the plan in Appendix 2. c. For each requested mercury early reduction credit, the additional controls th at are proposed to be implemented to reduce mercury emissions. [NAC 445B.3671.6]



### Tier 2 Unit(s) – Please provide the following:

a. An identification and description of any equipment for control of mercury emissions from all existing thermal units that emit mercury, including any presumptive NvMACT controls. In addition to the identification and description, please complete Section 5 of the Mercury Unit application form in Appendix 1. A separate Mercury Unit application form is required for each thermal unit that emits mercury. [Section 33.1 of amended NAC 445B] b. A proposed monitoring plan for each therma l unit that emits mercury consistent with the requirements of Section 33.2(b) of amended NAC 445B. Include the plan in Appendix 2.



### Phase 2 Application

Tier 1 or Tier 2 Unit(s) – Please provide the following:

a. A proposed monitoring plan consistent with the requirements of NAC 445B.3675.2. Include the plan in Appendix 2. b. The NvMACT analysis for each thermal unit that emits mercury c onsistent with the requirements of NAC 445B.3675.1. Include the analysis in Appendix 3.



### New or Modified Thermal Unit that Emits Mercury

a. Please provide the NvMACT analysis for each thermal unit that emits mercury consistent with the requirements of NAC 445B.3681.6. Include the analysis in Appendix 3.



### Request for De Minimis Designation

a. For a request for determination of de minimis mercury emissions, include a de minimis demonstration in Appendix 4. De minimis st atus is considered for each thermal unit. Demonstration must be at the individual unit level, but include cumulative impact of all de minimis units at a facility. [NAC 445B.3613 and NAC 445B.3657.3] b. De minimis demonstration must include, at a minimum: identification of the proposed thermal unit, a process description, location, unit manufacturer, un it model, serial number and fuel type used (or specify if electric). Identify if any exhaust stacks are shared and if mercury emission controls are utilized. [NAC 445B.295] c. Include potential to emit values based on unit operation at maximum design capacity at 8,760 hours per year. Supply laboratory test results, performance stack test results and calculations implemented to calculate potential to emit mercury emissions. Include a thorough discussion of any assumptions. [NAC 445B.295] d. Identify under what Air Quality Operating Permit the proposed units are contained and if the proposed units are designated as “insignificant ” or “non-permitted items.” [NAC 445B.295]Page 7 APPLICATION INFORMATION (CONTINUED)

9. The application mu st also contain: a. An identification of each thermal unit that emits mercury. In addition to the identification of each thermal unit that emits mercury, please complete Section 1 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.2 and NAC 445B.3681.2] b. A description of the production rates, operating sche dules, fuels, fuel use and raw materials to be used for each thermal unit that emits mercury. In additi on to the description, pl ease complete Sections 2 and 3 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emit s mercury. [NAC 445B.3671.3 and NAC 445B.3681] c. Limitations on the operation of stationary source or thermal unit that emits mercury or any work practices which may affect mercury emissions from th e thermal unit that emits mercury. Use Sections 4 and 5 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.4 and NAC 445B.3681.4] d. Requested emissions limits. Use Section 7 of the Mercury Unit application form in Appendix 1. Complete a separate Mercury Unit application form for each thermal unit that emits mercury. [NAC 445B.3671.7 and NAC 445B.3681.7]

11. Will the construction occur in more than one phase? Yes No

If the construction will occur in more than one phase, please provide the projected date of the commencement for each phase of construction (include addi tional phases if necessary): [NAC 445B.3687]

Phase 1: Phase 2: Phase 3:

12. For Application Submittal: Please remove the cover page, Table of Contents and General Information page. Submit the remainder of the application packet as your formal application. This should consist of, at a minimum, the Mercury Operating Permit to Construct Application cover page, the genera l Company Information and Application Information, and any applicable Appendices.Appendix 1, Page 1 

# Appendix 1

THERMAL MERCURY EMITTING UNIT APPLICATION FORMAppendix 1, Page 2 

### Instructions

PLEASE RESPOND SEPARATELY TO ITEMS 1 through 7 FOR EACH EMISSION UNIT, as appropriate. Each emission unit at the stationary source must be identified by completion of the application form contained in this appendix. The forms may be duplicated for as many thermal mercury emission units as needed. Complete all applicable attachments ( Appendix 1 ) included in this application package [NAC 445B.295].

Section 1. Equipment Description : Describe the processes and products by SIC, including any associated with an alternative operating scenario identified in this application, model number, manufacture date, dimensions and UTM coordinates. Section 2. Design Rate /Operating Parameters : Describe all production ra tes, operating schedules and materials used in the process. Section 3. Fuel Usage : Describe all fuels and fuel usage. Section 4. Pollution Control Equipment/Exhaust Stack Parameters : Identify and describe all air pollution control equipment. Section 5. Work Practice Standards : provide information on limitations on the operation or any standards for work practices which affect emissions for a ll regulated air pollutants. [NAC 445B.295.5] Section 6. Compliance Monitoring Devices and Activities : Identify and describe any equipment for the control of air pollution and any devices or activities for monitoring compliance with emission limitations. Section 7. Requested Emission Limits : Provide the requested emission limits for each emission unit. Include the emission rates of total mercury . The emission rates must be described in pounds per hour and pounds per year and any other units of measure for mercury emissions as may be proposed.

Alternative Operating Scenarios : Complete a separate application form for each emission unit having an alternative operating scenario. (A common example of an alternative operating scenario is a steam boiler that utilizes natural gas as the primary fuel, but may combust diesel fuel as an alternate fuel source) . Please check the box in the upper right hand corner of each application form for emission units requesting an alternative operating scenario. Additionally, for each emi ssion unit application form requesting an alternative operating scenario: 1. Define each alternative operating scenario; 2. Provide an alternative monitoring plan for each unit, for which an alternative operating scenario is requested, in Appendix 2, if different from the m onitoring plan provided for the primary operating scenario. Contemporaneous log entries must be provided every time the source changes from one scenario to another.Appendix 1, Page 3 System 66A, TU4.013, Autoclave Circuit 1, Autoclave #1



### THERMAL MERCURY EMITTING UNIT APPLICATION FORM MERCURY OPERATING PE RMIT TO CONSTRUCT

Check here if this is an alternative operating scenario 

### Section 1 - Equipment Description

a. Type of equipment System 66A, TU4.013, Autoclave Circuit 1, Autoclave #1

b. Standard Industrial Classification (SIC) Code 1041

c. Manufacturer of equipment Eaton

d. Model number not specified Serial number not specified *Equip. number not specified

e. Date equipment manufactured: not specified

f. UTM Coordinates 4,536,042 meters N; 554,723 meters E; Zone 11 (Please specify NAD 27 or NAD 83 ; Method used to obtain coordinates: AutoCAD file overlay onto USGS map)


### g. Basic equipment dimensions (feet): L N/A W N/A H N/A *The equipment number is the facility's own num bering system for this piece of equipment.



### Section 2 - Design Rate/Operating Parameters



### a. Maximum design capacity (tons per hour) 130

b. Requested operating rate (tons per hour)*

c. Requested operating time: (time of day)* to

Hours per day 0-24 Days per year 365, 8,760 hr/yr

d. Batch load or charge weight (tons) (if applicable) N/A

e. Total hours required to process batch or charge (if applicable) N/A

f. Maximum operating rate (tons per year) not specified

g. Requested operating rate (tons per year)*

f. Type of material processed ore

*Note: Please complete if other than th e maximum design capacity (tons per hour and tons per year) and/or the maximum hours of operation (24 hours per day, 8,760 hours per year) are being requested. The permit will be limited to these values.Appendix 1, Page 4 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66A - TU4.013

Section 3 - Fuel Usage / Heat Source

Electric Unit



### Type of Fuel Amount Used Per Hour Heat Content (specify in Btus) Ash Content

(% by weight) Sulfur Content ( % by weight) Trace Elements

(% by weight) Oil- Specify Type(s)

none gallons N/A N/A N/A N/A

none gallons N/A N/A N/A N/A

Gasoline none gallons N/A N/A N/A N/A Propane none cubic feet N/A N/A N/A N/A

Natural Gas none cubic feet N/A N/A N/A N/A
*Waste Oil none gallons N/A N/A N/A N/A

Other none N/A N/A N/A N/A

Type of

Coal Fuel Amount Used Per Hour (tons) Heat Content (specify in BTUs) Ash Content

(% by weight) Sulfur Content

(% by weight) Trace Elements

(% by weight) Percent moisture Percent volatile
matter Percent fixed carbon

Coal - Specify Type(s)

none N/A N/A N/A N/A N/A N/A N/A N/A

If more than one type of fuel is combusted, under this opera ting scenario please specify prim ary fuel and percentage on a maximum hourly and annual ba sis (if fuel blending is the primary fuel, identif y percentages of each fuel blended). Attach additional information to this form if necessary.

*Firing of waste oil will require multi metals test to insure fuel is non-hazardous.Appendix 1, Page 5 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66A - TU4.013

Section 4 - Pollution Control Equipment/ Exhaust Stack Parameters (this section must be completed) -Complete for emissions exhausting through a stack, chimney or vent : (baghouse, wet scrubber, cyclone, sulfur impregnated carbon filter, uncontrolled stack, etc.) Control #1* Control #2 Type of Control (See Note 1 ) venturi wet dust scrubber



### Pollutant(s) Controlled particulates and mercury



### Manufacturer Ducon



### Manufacturer's Guarantee (see Note 2 ) N/A



### Stack height (feet from ground level) 100



### Stack inside diameter (feet) 3.67



### Temperature (°F) at design capacity 223



### Stack exit velocity (feet per second) 9.97



### Gas volume flow rate: Actual cubic feet per minute 6,330



### Gas volume flow rate: Dry standard cubic feet per minute 1,395**



### Unusual stack characteristics (e.g. raincap, horizontal discharge) 65.2% moisture

* Stack parameters are taken from the APT 7/29/2009 stack test for Hg. ** Maximum flow expected to be 2,500 dscfm.

Note 1 : Specify "uncontrolled" if no pollution control device is installed. Note 2 : Manufacturer's guarantee of control efficiency must be attached to this form.Appendix 1, Page 6 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66A - TU4.013

Section 5 - Identify and Describe Work Practice Standards, Etc. (attach additional pages if necessary)

(Eg., 1. Baghouse housing a nd bags will be inspected weekly for holes/leaks.)

Work Practices:

Autoclave #1: (a) The carbonate/sulfide ratio of the ore slurry feed will be maintained below 3.

Venturi Scrubber: (a) The pressure drop across the venturi scrubber will be maintained at or below 70 inches of water. (b) The water flow rate to the venturi scrubber will be maintained at or above 50 gallons per minute.



### Section 6 - Identify and Describe Comp liance Monitoring Devices or Activities (attach additional pages if necessary)

(Eg., Emissions from this unit will be monitored by CEMS for mercury.)

Monitoring and Recordkeeping:

(a) The carbonate/sulfid e ratio of the ore feed to Autoclave #1 (TU4 .013) will be monitored and recorded once, during each shift that TU4.013 is in operation. (b) The pressure drop across the vent uri scrubber will be mo nitored and recorded once, during each day of operation. (c) The water flow rate to the venturi scrubber will be monitored and recorded once, during each day of operation.

Testing Requirements:

Annual Testing

Before the conclusion of th e calendar year, Permittee shall conduct and record a Method 29 (or alternative test method approved by the Director) compliance test fo r mercury on the exhaust stack of TU4.013.

Annual Reporting

The Permittee shall: 1. Report the mercury co-product on an annual basis. 

### 2. Report the mercury emissions on an annual basis whic h must be based on mercury emissions test data.Appendix 1, Page 7 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66A - TU4.013

Section 7 - Proposed Emission Rates

Pollutant Potential to Emit (pounds/hour*) Potential to Emit (tons/year) Calculation (including reference or emissions tests) on Which Emissions Information is Based (attach supporting information including dates of tests/methods, if necessary) Total Mercury (all forms) 0.0214 0.094 Based on proposed concentration standard, maximum flow, and annual operating limit.


### Total Mercury (alternative emissions limitations) 4 x 10 -4 

### gr/dscf Proposed interim NvMACT emission limit. See page 3 of Appendix 2.

*Note: In addition to lb/hr, alternative emissions limitations (e.g., lb/MMBtu, ppm, grains/dsc f) may be requested by the appl icant. If alternative emissions limitations are requested, please clearly describe the units in column 2 above. Use additional lines, as needed.Appendix 1, Page 8 System 66B, TU4.014-TU4.015, Autoclav e Circuit 2, Autoclaves #2 & #3



### THERMAL MERCURY EMITTING UNIT APPLICATION FORM MERCURY OPERATING PE RMIT TO CONSTRUCT

Check here if this is an alternative operating scenario 

### Section 1 - Equipment Description

a. Type of equipment System 66B, TU4.014-TU4.015, Autoclave Circuit, Autoclaves #2 & #3

b. Standard Industrial Classification (SIC) Code 1041

c. Manufacturer of equipment Eaton

d. Model number not specified Serial number not specified *Equip. number not specified

e. Date equipment manufactured: 1991

f. UTM Coordinates 4,536,082 meters N; 554,709 meters E; Zone 11 (Please specify NAD 27 or NAD 83 ; Method used to obtain coordinates: AutoCAD file overlay onto USGS map)


### g. Basic equipment dimensions (feet): L N/A W N/A H N/A *The equipment number is the facility's own num bering system for this piece of equipment.



### Section 2 - Design Rate/Operating Parameters



### a. Maximum design capacity (tons per hour) 200, each

b. Requested operating rate (tons per hour)*

c. Requested operating time: (time of day)* to

Hours per day 0-24 Days per year 365, 8,760 hr/yr, each

d. Batch load or charge weight (tons) (if applicable) N/A

e. Total hours required to process batch or charge (if applicable) N/A

f. Maximum operating rate (tons per year) not specified

g. Requested operating rate (tons per year)*

f. Type of material processed ore

*Note: Please complete if other than th e maximum design capacity (tons per hour and tons per year) and/or the maximum hours of operation (24 hours per day, 8,760 hours per year) are being requested. The permit will be limited to these values.Appendix 1, Page 9 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66B - TU4.014-TU4.015

Section 3 - Fuel Usage / Heat Source

Electric Unit



### Type of Fuel Amount Used Per Hour Heat Content (specify in Btus) Ash Content

(% by weight) Sulfur Content ( % by weight) Trace Elements

(% by weight) Oil- Specify Type(s)

none gallons N/A N/A N/A N/A

none gallons N/A N/A N/A N/A

Gasoline none gallons N/A N/A N/A N/A Propane none cubic feet N/A N/A N/A N/A

Natural Gas none cubic feet N/A N/A N/A N/A
*Waste Oil none gallons N/A N/A N/A N/A

Other none N/A N/A N/A N/A

Type of

Coal Fuel Amount Used Per Hour (tons) Heat Content (specify in BTUs) Ash Content

(% by weight) Sulfur Content

(% by weight) Trace Elements

(% by weight) Percent moisture Percent volatile
matter Percent fixed carbon

Coal - Specify Type(s)

none N/A N/A N/A N/A N/A N/A N/A N/A

If more than one type of fuel is combusted, under this opera ting scenario please specify prim ary fuel and percentage on a maximum hourly and annual ba sis (if fuel blending is the primary fuel, identif y percentages of each fuel blended). Attach additional information to this form if necessary.

*Firing of waste oil will require multi metals test to insure fuel is non-hazardous.Appendix 1, Page 10 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66B - TU4.014-TU4.015

Section 4 - Pollution Control Equipment/ Exhaust Stack Parameters (this section must be completed) -Complete for emissions exhausting through a stack, chimney or vent : (baghouse, wet scrubber, cyclone, sulfur impregnated carbon filter, uncontrolled stack, etc.) Control #1* Control #2 Type of Control (See Note 1 ) venturi wet dust scrubber



### Pollutant(s) Controlled particulates and mercury



### Manufacturer Hosokawa



### Manufacturer's Guarantee (see Note 2 ) N/A



### Stack height (feet from ground level) 100



### Stack inside diameter (feet) 6.00



### Temperature (°F) at design capacity 197



### Stack exit velocity (feet per second) 14.80



### Gas volume flow rate: Actual cubic feet per minute 25,106



### Gas volume flow rate: Dry standard cubic feet per minute 3,927**



### Unusual stack characteristics (e.g. raincap, horizontal discharge) 76.1% moisture

* Stack parameters are taken from the APT 7/28 & 7/30/2009 stack test for Hg. ** Maximum flow expected to be 5,000 dscfm.

Note 1 : Specify "uncontrolled" if no pollution control device is installed. Note 2 : Manufacturer's guarantee of control efficiency must be attached to this form.Appendix 1, Page 11 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66B - TU4.014-TU4.015

Section 5 - Identify and Describe Work Practice Standards, Etc. (attach additional pages if necessary)

(Eg., 1. Baghouse housing a nd bags will be inspected weekly for holes/leaks.)

Work Practices:

Autoclaves #2 & #3: (a) The carbonate/sulfide ratio of the ore slurry feed will be maintained below 3.

Venturi Scrubber: (a) The pressure drop across each venturi scrubber will be maintained at or below 70 inches of water. (b) The water flow rate to each ve nturi scrubber will be maintained at or above 50 gallons per minute.



### Section 6 - Identify and Describe Comp liance Monitoring Devices or Activities (attach additional pages if necessary)

(Eg., Emissions from this unit will be monitored by CEMS for mercury.)

Monitoring and Recordkeeping:

(a) The carbonate/sulf ide ratio of the ore feed to Autoclaves #2 and #3 (TU4.014 & TU4.015) will be monitored and recorded once, during each shift that TU 4.014 and TU4.015, each is in operation. (b) The pressure drop across each venturi scrubber will be monitored and recorded once, during each day of operation. (c) The water flow rate to each venturi scrubber will be monitored and recorded once, during each day of operation.

Testing Requirements:

Annual Testing

Before the conclusion of th e calendar year, Permittee shall conduct and record a Method 29 (or alternative test method approved by the Director) compliance test for mercu ry on the exhaust stack of TU4.014 and TU4.015.

Annual Reporting

The Permittee shall: 1. Report the mercury co-product on an annual basis. 

### 2. Report the mercury emissions on an annual basis whic h must be based on mercury emissions test data.Appendix 1, Page 12 

### THERMAL MERCURY EMITTING UNIT APPLICATION FORM (CONTINUED)

For Unit: System 66B - TU4.014-TU4.015

Section 7 - Proposed Emission Rates

Pollutant Potential to Emit (pounds/hour*) Potential to Emit (tons/year) Calculation (including reference or emissions tests) on Which Emissions Information is Based (attach supporting information including dates of tests/methods, if necessary) Total Mercury (all forms) 0.0429 0.188 Based on proposed concentration standard, maximum flow, and annual operating limit.


### Total Mercury (alternative emissions limitations) 4 x 10 -4 

### gr/dscf Proposed interim NvMACT emission limit. See page 3 of Appendix 2.

*Note: In addition to lb/hr, alternative emissions limitations (e.g., lb/MMBtu, ppm, grains/dsc f) may be requested by the appl icant. If alternative emissions limitations are requested, please clearly describe the units in column 2 above. Use additional lines, as needed.Appendix 2, Page 1 

# Appendix 2

Monitoring Plan For Each:

(Check Appropriate Box) 

# Phase 1, Tier 1; Phase 1, Tier 2; Phase 2; or New or Modified

Thermal Mercury Emitting UnitAppendix 2, Page 2 

# PHASE 2 MONITORING PLAN

Air Pollution Equipment:

(a) Exhaust gases from TU4.013 (System 66A, Autoclave # 1) shall be ducted to a control system consisting of:

a. Venturi wet dust scrubber on the exhaust stream of TU4.013 (b) Exhaust gases from TU4.014 and TU4.015 (System 66B, Autocl aves #2 and #3) shall be ducted to a control system consisting of:

a. Venturi wet dust scrubber on the exhaust stream of TU4.014 b. Venturi wet dust scrubber on the exhaust stream of TU4.015 (c) Stack Parameters for TU4.013

a. Height: 100 ft b. Diameter: 3.67 ft

c. Stack Temperature: Approximately 223°F d. Flow: Maximum volume flow rate of a pproximately 2,500 dry standard cubic feet per minute (dscfm) (d) Stack Parameters for TU4.014 and TU4.015

a. Height: 100 ft b. Diameter: 6.0 ft

c. Stack Temperature: Approximately 197°F d. Flow: Maximum volume flow rate of a pproximately 5,000 dry standard cubic feet per minute (dscfm)

Operating Requirements:

(a) Limitations of operation

a. The maximum allowable throughput ra te for TU4.013 shall not exceed 130 tons per any one-hour period. b. The maximum allowable throughput ra te for TU4.014 and TU4.015, each, shall not exceed 200 tons per any one-hour period.

c. The interim mercury emission limit during the demonstra tion period for establishment of the final mercury emission limit for TU4.013 throu gh TU4.015, each, shall be 4x10 -4 gr/dscf mercury. d. Hours i. TU4.013 through TU4.015, each, may operate 24 hours per day ii. TU4.013 through TU4.015, each, may operate 8,760 hours per calendar year.

Work Practices:

Autoclaves #1 through #3: (a) The carbonate/sulfide ratio of the ore slurry feed to each autoclave will be maintained below 3.

Venturi Scrubbers: (b) The pressure drop across each venturi scrubber will be maintained at or below 70 inches of water. (c) The water flow rate to each venturi scrubber will be maintained at or abov e 50 gallons per minute.

Monitoring and Recordkeeping:

(a) The carbonate/sulfide ratio of the ore feed to each autoclave will be monitored and recorded once, during each shift that each autoclave is in operation. (b) The pressure drop across each venturi scrubber will be monitored and recorded once during each day of operation. (c) The water flow rate to each venturi scrubber will be m onitored and recorded once dur ing each day of operation.

Testing Requirements:

Annual Testing

Before the conclusion of the calendar year , Permittee shall conduct and record a Method 29 (or alternative test method approved by the Director) compliance test for mercury on th e exhaust stacks of TU4.013 and TU4.014/TU4.015, each.

Annual Reporting

The Permittee shall: 1. Report the mercury co-product on an annual basis. 2. Report the mercury emissions on an annual basis whic h must be based on mercury emissions test data.PROJECT TITLE: BY: 

### Air Sciences Inc. Barrick Goldstrike E. Steen

PROJECT NO: PAGE: OF: SHEET: 59-43-80 1 1 1 ENGINEERING CALCULATIONS SUBJECT: DATE: A utoclave Hg Standard A ugust 9, 2010

A utoclave stack test data

Emissions Unit Control lb/hr gr/dscf Test Info Autoclave 1 Venturi Scrubber 6.63E-03 3.05E-04 8/28/1990 Autoclave 1 Venturi Scrubber 2.30E-03 1.40E-04 07/10/1991 Autoclave 2 & 3 Venturi Scrubber 1.23E-03 2.01E-05 09/17/1992 Autoclave 4 Venturi Scrubber 1.13E-03 1.37E-04 05/02/2006 Autoclave 4 Venturi Scrubber 2.87E-03 2.63E-04 05/03/2006 Autoclave 4 Venturi Scrubber 1.07E-03 6.20E-05 07/23/2009 Autoclave 5 & 6 Venturi Scrubber 1.17E-03 3.65E-05 07/24/2009 A utoclave 2 & 3 Venturi Scrubbe r 8.63E-04 2.55E-05 07/28/2009 Autoclave 1 Venturi Scrubber 7.13E-04 5.92E-05 07/29/2009 Autoclave 2 & 3 Venturi Scrubber 9.00E-04 3.53E-05 04/28/2010 A utoclave 5 & 6 Venturi Scrubbe r 3.30E-03 9.49E-05 06/08/2010

Average Hg Concentration 1.1E-04 gr/dscf Standard Deviation 9.7E-05 gr/dscf Three standard deviations 2.9E-04 gr/dscf 99.7% confidence interval 4.0E-04 gr/dscf

NvMACT Standard 4.0E-04 gr/dscf

Appendix 2, Page 3 0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 3.00E-04 3.50E-04Hg Concentration (gr/dscf) Autoclaves Hg Concentration from Stack Testing

Appendix 2, Page 3Appendix 3, Page 1 

# Appendix 3

Nevada MACT Analysis For Each:

(Check Appropriate Box)



# Phase 2; New or Modified; or Not Applicable

Thermal Mercury Emitting UnitAppendix 3, Page 2 

# CONTENTS Page

BARRICK GOLDSTRIKE MINES INC. (GOLDSTRIKE) NV MACT ANALYSIS FOR AUTOCLAVES 1 THROUGH 3 ..................... 4

Introduction .................................................................................................................. ................................................................. 4 Source Description ............................................................................................................ ........................................................... 4 NvMACT Analysis ............................................................................................................... .......................................................... 7

Part I – Existing Similar Thermal Units ....................................................................................... .............................................. 7

Mercury Co ntrols .............................................................................................................. ................................. 7

Wet Scr ubbers ................................................................................................................. ............................... 7 Work Prac tices ................................................................................................................ ................................... 9 Mercury Em issions ............................................................................................................. ............................... 9 Mercury Cont rol Costs ......................................................................................................... ........................... 11 Non-Air Quality Health and Environmenta l Impacts and Energy Requirements ............................................ 12 Part II – Other Controls and/or Work Practices ................................................................................ ...................................... 13

Other Mercury Control Options ................................................................................................. ...................... 13

Boliden Norzinc ............................................................................................................... ............................ 13 Selenium Scrubbers ............................................................................................................ ......................... 14 Wet Electrostatic Precipitators ............................................................................................... ...................... 14 Activated Carb on Filters ...................................................................................................... ........................ 14 Activated Carbon Injection .................................................................................................... ...................... 25 Selenium Filters .............................................................................................................. ............................. 25 Condensers .................................................................................................................... ............................... 26 Other Work Practi ces .......................................................................................................... ............................. 26 Part III - Proposed NvMACT .................................................................................................... .............................................. 28

Analysis of Nv MACT Criteria ................................................................................................... ..................... 29

445B.3677.3(b)(1)(I) – The Cost of Ac hieving Mercury Emi ssions Reduc tion .......................................... 29 445B.3677.3(b)(1)(II) – Non-air Quality Health and Environmental Impacts and Energy Requirements .. 32 445B.3677.3(b)(2) – Process Chan ges or Substitution of Materials to Reduce Mercury Emissions ........... 33 445B.3677.3(b)(3) – Enclosure of Systems or Processes to Eliminate Mercury Emissions ........................ 33 445B.3677.3(b)(4) – Collection, Capture or Treatment of Me rcury Emissions .......................................... 33 445B.3677.3(b)(5) – Design, Equipment, Work Practice, or Operational Standards of the Thermal Unit .. 33 445B.3677.3(b)(6) – Differences in Age, Remaining Operating Life, Configurations, Ore Mercury Concentration, Size, and Any Other Relevant Factors of the Sim ilar Thermal Units .................................. 33 Proposed NvMACT ............................................................................................................... .......................... 34 Proposed Mercury Emission Limit ............................................................................................... ................... 35

ENDNOTES ...................................................................................................................... .............................................................. 36

Appendix A - General Arrangement .............................................................................................. ............................................. 38 Appendix B - Piping and Instrumentation Diagrams .............................................................................. ..................................... 48 Appendix C - Process Flow Diagrams ............................................................................................ ............................................ 65 Appendix D - Process Design Criteria .......................................................................................... .............................................. 69Appendix 3, Page 3 

### Tables

Table 3.1: Autoclave Stack Test ing Mercury Emissions Summary ................................................................. ............................. 10
Table 3.2: Autoclave Sta ck Test Mercury Speciation ........................................................................... ....................................... 11 Table 3.3: Capital and Annual Operating Costs of Option 1 .................................................................... .................................... 16 Table 3.4: Capital and Annual Operating Costs of Option 2 .................................................................... .................................... 18 Table 3.5: Capital and Annual Operating Costs of Option 3 .................................................................... .................................... 19 Table 3.6: Capital and Annual Operating Costs of the Alkaline Control System ................................................. ........................ 22 Table 3.7: Installation and Operating Costs of the Acidic Control System ..................................................... .............................. 24 Table 3.8: Acidic Autoclaving Mercury Volatilization ......................................................................... ........................................... 27 Table 3.9: Annual Mercury Emissions from Ac idic Operation of Autoclaves 1 through 3 .......................................... .................. 29 Table 3.10: Installation and Operating Costs of the Acidic Control System .................................................... ............................. 30 Table 3.11: Annualized Installation and Operating Costs of the Acidic Control System ......................................... ..................... 31 Table 3.12: Cost Effectiveness of the Acidic Control System .................................................................. .................................... 32



### Figures Figure 3.1: Autoclave Circuit Process Flow Diagram ........................................................................... .......................................... 5 Figure 3.2: Autoclave Circuit Emission Controls .............................................................................. .............................................. 6 Figure 3.3: Rectangular Throat Venturi Scrubber .............................................................................. ............................................ 8 Figure 3.4: Carbon Adsorption Option 1 ....................................................................................... ............................................... 16 Figure 3.5: Carbon Adsorption Option 2 ....................................................................................... ............................................... 17 Figure 3.6: Carbon Adsorption Option 3 ....................................................................................... ............................................... 19 Figure 3.7: Alkaline Control System .......................................................................................... ................................................... 21 Figure 3.8: Acidic Control System ............................................................................................ .................................................... 23 Figure 3.9: Mercury Saturation Pressure Curve ................................................................................ .......................................... 26Appendix 3, Page 4 

# BARRICK GOLDSTRIKE MINES INC. (GOLDSTRIKE) NVMACT ANALYSIS FOR AUTOCLAVES 1 THROUGH 3

Introduction

Barrick Goldstrike Mines Inc (Goldstrike) operates six autoclaves that vent to four stacks. The autoclaves are used to oxidize sulfide ore with pressure, steam, and oxygen. Historically, Goldstrike has used acidic autoclaving to process the sulfide ore; however, due to the changing ore characteristics, Goldstrike plans to operate three autoclaves (Autoclaves 4 through 6) in an alkaline mode of operation in the future. In June 2010, Goldstrike submitted a Phase-2 Application to modify Autoclaves 4 through 6 for alkaline operation. The remaining three auto claves (Autoclaves 1 through 3) will continue to operate in the acidic mode of operation.

Per NAC 445B.3675.1, a Nevada Maximum Achievable Control Technology (NvMACT) analysis is required to be conducted for existing thermal un its that emit mercury as a part of the Phase-2 Application. The NvMACT analysis for Autoclaves 1 through 3 provided herein addresses all the requirements of NAC 445B.3675.1.


## Source Description

In the autoclave circuit, sulfide ore is oxidized (see Figure 3.1). In acidic autoclaving, sulfide ore slurry from the wet grinding mills is first thickened in thic kener tanks. The slurry is then acidulated with sulfuric acid in acidulation tanks. Sulfide ore slurry from the acidulation tanks is pre-heated and then oxidized in the autoclaves with pressure, steam, and oxygen. The off-gas from each autoclave passes through a dedicated venturi scrubber before being released to the atmosphere (the exhaust from Autoclaves 2 and 3 and Autoclaves 5 and 6 are ducted together downstream of the venturi scrubbers for a total of four stacks) (see Figure 3.2) . When the gas exits the venturi scrubber it is saturated with water.Appendix 3, Page 5 Figure 3.1: Autoclave Circuit Process Flow Diagram

STEAM GENERATION

PLANT TO ATMOSPHERE SLURRY COOLER SURGE TANKS FLASH TANKS SLURRY COOLERS

STEAM AUTOCLAVES

AIR LIQUIDE OXYGEN PLANT O 2 S2.015 - S2.020 SPLASH CONDENSERS

COOLING TOWERS WATER ORE FROM WET GRINDING PROCESS

TO CIL TANKS SLAKED LIME LIME SLAKERS

HEAT PRE OXIDATION THICKENERS

TO ATMOSPHERE

WET SCRUBBERS TO RECLAIM WATER TANK

SULFURIC

ACID TANKS ACIDULATION TANKS

NEUTRALIZATION TANKS

FLOW OF GOLD LEGEND:

MINOR FLOW WATERAppendix 3, Page 6 Figure 3.2: Autoclave Circuit Emission Controls

Autoclave #1

S2.015 Autoclave #1

Venturi Scrubber

Autoclave #3 S2.017 Autoclave #2

S2.016 Autoclave #2

Venturi Scrubber Autoclave #3 Venturi Scrubber To Atmosphere

(Stack #2) To Atmosphere

(Stack #1)

Autoclave #4 S2.018 Autoclave #4

Venturi Scrubber

Autoclave #6 S2.020 Autoclave #5

S2.019 Autoclave #5

Venturi Scrubber Autoclave #6 Venturi Scrubber To Atmosphere

(Stack #4) To Atmosphere

(Stack #3)Appendix 3, Page 7 

## NvMACT Analysis

Part I – Existing Similar Thermal Units
Part I of this NvMACT analysis pr ovides a list of the similar existing thermal units used for precious metal mining and describes the controls and work practices used to reduce mercury emissions. All information required by NAC 445B.3675, as described below, is provided herein:

NAC 445B.3675 Existing thermal unit that emits mercury: Contents of phase-2 application.

1.(b) Sets forth a list of similar th ermal units that emit mercury which a re used for precious metal mining that

includes, without limitation:

(1) Any methods or technologies to control mercury emi ssions which are associated wi th the thermal units that

emit mercury;

(2) The level of mercury emissions associated with each method or te chnology to control mercury emissions

from the thermal units that emit mercury;

(3) The design for each method or technology to cont rol mercury emissions from the thermal units that emit

mercury;

(4) Costs associated with reductions of mercury emissions as a result of ea ch method or technology to control

mercury emissions from the therm al units that emit mercury;

(5) Costs associated with energy for each method or technology to control mercury emissions from the thermal

that emit mercury; and

(6) Consistent with section 112(d)(2) of the Act, an y nonair quality health an d environmental impacts and

energy requirements for each method or technology to control mercury emissions fr om the thermal units that emit mercury.



### Mercury Controls
An examination of the Nevada Mercury Control Program (NMCP) Phase-2 Applications 1 showed that there is only one other precious metal mining facility in Nevada with an existing autoclave circuit. At both Goldstrike and Newmont Twin Creeks, the existi ng control for these thermal units is venturi wet
scrubbers.



### Wet Scrubbers
All of the existing autoclaves employ a venturi scrubb er as an off-gas control. The venturi scrubbers are installed primarily to control particulate emissions. Wet scrubbers may control oxidized mercury, 2 as this form of mercury is soluble in the scrubber wate r, and elemental mercury, if the scrubber exhaust temperature is decreased to below the mercury saturation temperature.

Venturi wet scrubbers control particulates, including particulate mercury, through impaction, diffusion, interception, and/or adsorption of the pollutant onto droplets of liquid. 3 Venturi scrubbers use a converging then diverging flow channel such that th e area of the channel decreases then increases alongAppendix 3, Page 8 the length of the channel. The narrowest area is call ed the throat. As the exhaust gas enters the venturi scrubber, the decrease in area causes the gas velocity and turbulence to increase. The scrubbing water is injected either slightly upstream of or directly into the throat section. As the scrubbing solution is injected, the turbulence in the throat causes it to atomize, which improves gas-liquid contact. 3 After passing through the throat, the gas-liquid mixture de celerates and causes additional particle-droplet impacts and agglomeration of the droplets. Before the gas exits the scrubber, the liquid droplets are separated from the gas in an entrainment section. 3

As the gas passes through the venturi scrubber, there is a drop in pressure. For venturi scrubbers in general, the greater the pressure drop, the higher the particulate control efficiency. However, for autoclaves, the temperature and pressu re of the autoclave itself is maintained by limiting the release of steam and off-gas. Therefore, when the gas flow passing through the scrubber is low, there is low pressure drop across the scrubber.

The liquid to gas ratio also affects venturi scrubber ef ficiency. There must be sufficient liquid injected into the scrubber to allow for coverage over the throat area and to create sufficient collection targets. After an optimal point, adding excess liquid to a scrubber does not increase the particulate control efficiency. The liquid to gas ratio for wet scrubbers ty pically ranges from 4 to 20 gallons per 1,000 actual cubic feet (gal/kacf). 4 A diagram of a typical venturi scrubber is provided as Figure 3.3.

Figure 3.3: Rectangular Throat Venturi Scrubber 5Appendix 3, Page 9 

### Work Practices
Work practices associated with autoclaves and ve nturi scrubbers include mo nitoring the autoclave throughput and monitoring the venturi scrubber flow rate and pressure drop. Autoclaves operate under pressure and are ducted such that all the exhaust is vented through the venturi scrubber. Total exhaust flow and emissions are limited by limiting the release of steam and off-gas to the venturi scrubber as previously discussed.



### Mercury Emissions
The actual mercury emissions from the autoclaves at precious metal mining facilities in Nevada were
obtained from stack tests. 6 Table 3.1 provides the po und-per-hour (lb/hr) emission rate as well as the mercury concentration data for autoclaves.

### Table 3.1: Autoclave Stack Testing Mercury Emissions Summary

Emissions Hg Conc. Mine Unit Control lb/hr gr/dscf Test Info a

Twin Creeks Mine Phase I & II Autoclave Venturi Scrubber 1.16E-01 1.12E-03 10/21/1997

Autoclave Venturi Scrubber 5.77E-02 1.29E-03 06/22/1998

Autoclave Venturi Scrubber 1.53E-02 6.57E-04 01/27/2001

Phase I Autoclave Venturi Scrubber 8.25E-02 1.27E-03 10/04/2005

Phase I Autoclave Venturi Scrubber 3.87E-02 5.81E-04 10/04/2005

Phase I Autoclave Venturi Scrubber 5.26E-02 9.68E-04 06/13/2007

Phase I Autoclave Venturi Scrubber 4.34E-02 8.37E-04 06/13/2007

Phase I Autoclave Venturi Scrubber 6.55E-02 1.02E-03 06/15/2007

Phase I Autoclave Venturi Scrubber 6.62E-02 1.15E-03 06/15/2007

Phase II Autoclave Venturi Scrubber 3.30E-02 6.06E-04 06/16/2007

Phase II Autoclave Venturi Scrubber 2.54E-02 4.23E-04 06/16/2007

Phase I Autoclave Venturi Scrubber 8.47E-02 1.72E-03 08/18/2008

Phase II Autoclave Venturi Scrubber 3.30E-02 6.73E-04 08/21/2008

Barrick Goldstrike Mine Autoclave 1 Venturi Scrubber 6.63E-03 3.05E-04 08/28/1990

Autoclave 1 Venturi Scrubber 2.30E-03 1.40E-04 07/10/1991

Autoclave 2 & 3 Venturi Scrubber 1.23E-03 2.01E-05 09/17/1992

Autoclave 4 Venturi Scrubber 1.13E-03 1.37E-04 05/02/2006

Autoclave 4 Venturi Scrubber 2.87E-03 2.63E-04 05/03/2006

Autoclave 4 Venturi Scrubber 1.07E-03 6.20E-05 07/23/2009

Autoclave 5 & 6 Venturi Scrubber 1.17E-03 3.65E-05 07/24/2009

Autoclave 2 & 3 Venturi Scrubber 8.63E-04 2.55E-05 07/28/2009

Autoclave 1 Venturi Scrubber 7.13E-04 5.92E-05 07/29/2009

Autoclave 2 & 3 Venturi Scrubber 9.00E-04 3.53E-05 04/28/2010 b

Autoclave 5 & 6 Venturi Scrubber 3.30E-03 9.49E-05 06/08/2010 b

a Obtained from the Nevada Mercury Control Program (NMCP) Mercury Emission Management System (MEMS) database.

b Source Emissions Test Report for Barrick Goldstrike Mines, Inc. Mercury Testing - EPA Method 29. MOPTC No. AP1041-2221. APT Project BAR0064. August 6, 2010.

Appendix 3, Page 10Appendix 3, Page 11 Ontario Hydro Method (OHM) stack test reports provid ed mercury speciation data for the autoclaves at Goldstrike. Flue-gas Absorbent Mercury Speciation (FAMS) test data was available for Newmont Twin Creeks. For all these autoclaves, the test data is repr esentative of an autoclave controlled by a venturi wet scrubber. The mercury speciation data is provided in Table 3.2.

Table 3.2: Autoclave Stack Test Mercury Speciation 7,8,9

Mine Source Controls Elemental Mercury Oxidized Mercury Particulate Mercury

Goldstrike Autoclave 1 Venturi Scrubber 92.8% 5.1% 2.2%

Autoclaves 2 & 3 Venturi Scrubber 69.8% 23.3% 6.9%

Autoclave 4 Venturi Scrubber 78.1% 8.3% 13.6%

Autoclaves 5 & 6 Venturi Scrubber 66.4% 26.8% 6.7%

Twin Creeks Phase I Autoclave Venturi Scrubber 97.9% 1.6% 0.5%

Average 81.0% 13.0% 6.0%

As shown by Table 3.2, a majority of the emissions from the existing autoclaves is in the form of elemental mercury (81 percent on average). A smalle r percentage of the emissions is oxidized mercury (13 percent on average), and the remaining smallest percentage of emissions is particulate mercury (6 percent on average).



### Mercury Control Costs
The Phase-2 Applications submitted by precious metal mining facilities in Nevada provided estimated total installed costs for the existing mercury cont rols for autoclaves. According to Newmont Twin Creek’s Phase-2 Application, the total installed costs of their venturi scrubbers for Autoclaves 1 and 2 were $347,000 and $364,000 in 2007 dollars, respec tively. The annual operating and maintenance costs were not provided.

Annual utility costs represent the cost of the energy required for each of the control technologies. Venturi scrubbers require energy for the pumps that circulat e scrubber solution through the system. Due to the fact that autoclaves are pressurized, the venturi scrubbers do not require a fan to push the exhaust through the scrubbers. According to the EPA Control Cost Manual, for a typical venturi scrubber with a liquid flow rate of 10 gallons per minute (gpm), a pressure of 20 pounds per square inch gauge (psig), and a pressure drop of 15 inches of water gauge (in. H 2 O g), the water pump energy requirement is estimated to be 0.233 horsepower per thousa nd cubic feet per mi nute (hp/1,000 cfm). 3 Assuming 24 hours per day and 7 days per week operation and an electricity cost of 9 cents per kilowatt-hour (kW-hr), the annual utility cost of a venturi scrubber with a gas flow rate of 30,000 actual cubic feet per minute (acfm) is approximately $4,000.Appendix 3, Page 12 

### Non-Air Quality Health and Environmental Impacts and Energy Requirements
For autoclaves, the typical venturi scrubber installati on uses process water as the scrubbing solution. This results in non-air quality health and environmental impacts from the discharge of the scrubbing solution. Venturi scrubbers also cause non-air quality health and environmental impacts from the increased energy consumption due to the scrubber water pump. For a typical venturi scrubber with a gas flow rate of 30,000 acfm, the energy requir ement is estimated at 46,000 kW-hr/yr.Appendix 3, Page 13 

### Part II – Other Controls and/or Work Practices
This part of the NvMACT analysis examines other control options and/or work practices that are not currently employed on existing autoclaves. (See Part I.)



### Other Mercury Control Options
In addition to the mercury technologies employed at existing autoclaves at precious metal mining facilities in Nevada, other mercur y control options for autoclaves have been examined. These control technologies include:

 Boliden Norzinc,

 selenium scrubbers,

 wet electrostatic precipitators (ESPs),

 activated carbon filters,

 activated carbon injection,

 selenium filters, and

 condensers.



### Boliden Norzinc
In the Boliden Norzinc process, a mercuric chloride solution reacts with the elemental mercury in the offgas to form a mercurous chloride precipitate, known as calomel, which is settled and recovered. This reaction occurs in a packed column. Once the solid is removed, the wash solution can be recirculated. A portion of the precipitate can be used to regenerate the mercuric chloride solution using chlorine gas. 10 The rest of the calomel is sent off-site for reclamation. The Boliden Norzinc process uses the following

reaction:

HgCl 2(sol’n) + Hg (gas) → 2HgCl (solid)

The Boliden Norzinc process is installed at Goldstrike’s roasters, which have a gas stream with high mercury content. The Boliden Norzinc process can achi eve outlet concentrations of 0.03 to 0.05 mg/Nm 3

. Because these outlet concentrations are similar to th e outlet mercury concentrations from the autoclaves, the Boliden Norzinc process would not be expected to provide significant additional mercury control.

The ideal operating temperature for the Boliden Norzinc process is 104  ̊ F. The average outlet temperature for autoclaves is approximately 190  ̊ F, and would therefore require gas stream cooling before control by the Boliden Norzinc process. Th e cooling of the saturated gas stream would require significant energy input, as energy is required to both condense the water and cool the gas stream. At the Goldstrike autoclaves, over 100 million British thermal units per hour (MMBtu/hr) would be required to cool the combined gas stream to 100  ̊ F.Appendix 3, Page 14 The Boliden Norzinc process has not been applied to an existing autoclave at precious metal mining facilities in Nevada. Thus, there is no basis for asse ssing its performance in such an application given the dissimilarities between the autoclaving process (and its characteristic emission stream) and those units/emission streams where Boliden Norzinc has been applied. In addition, this technology requires a significant capital investment and results in increased wastewater (process water containing chloride ions) and solid waste (calomel).



### Selenium Scrubbers
Selenium scrubbers use selenium or a selenium comp ound within a scrubber to react with the elemental mercury in the off-gas to form mercuric selenide (H gSe). Mercuric selenide has a lower vapor pressure than other common mercury compounds, which allows for mercury capture. The mercuric selenide is removed in a sludge separation circuit, which requires a thickener and HgSe reclamation. Sulfuric acid, at concentrations between 10 and 60 percent, is used as the wash solution for the process.

Selenium scrubbers are appropriate for gas stre ams with high mercury loading. The outlet concentrations from this process are typically higher than the concentrations achieved from the Boliden Norzinc process discussed above. Selenium scrubbers are not widely used due to the low removal efficiencies as well as the expensive reagent and reclamation requirements.



### Wet Electrostatic Precipitators
Wet electrostatic precipitators (ESPs) use electrostati c charges to move particulates from a gas stream
onto a collection surface. The electric field is crea ted through electrodes that are maintained at a high voltage. Wash water is used to clean th e particulates from the collection plates. 10 Wet ESPs are designed for saturated gas streams and have a maximum operating temperature of 170 to 190  ̊ F. Wet ESPs will collect dust, fumes, aerosol mist, and liquid droplets from a gas stream; however, they do not provide any effective control of oxidized or elemental mercury. 10 Therefore, gaseous elemental and oxidized mercury, which is a majority of autoclave mercury emissions, will not be controlled. The particulate mercury is already controlled by the existing venturi scrubber.



### Activated Carbon Filters
Carbon adsorption filters use activated carbon pa rticles to adsorb mercury from the gas stream. Adsorption occurs when gas molecules are passed through a bed of solid particles, and the gas molecules migrate from the gas stream to the surface of the so lids, where they are held by physical attraction. 11 Carbon impregnated with elemental sulfur increases the adsorption efficiency of the beds due to the mercury reacting with the sulfur to form mercury sulfide (HgS). Mercury sulfide has a lower vapor pressure than elemental mercury and is more readily removed. 10

Activated carbon beds control all types of mercury: particulate-bound, oxidized, and elemental. The mercury in the gas stream is adsorbed to the carbon and collected as carbon loaded with mercury. Once the carbon reaches adsorptive capacity, it is replaced, and the spent carbon is reclaimed. Monitoring of the carbon bed mercury content is performed to ensure that the mercury loading does not exceed theAppendix 3, Page 15 value recommended by the manufacturer. For activate d carbon beds, the typical carbon loading capacity is approximately 20 percent (or more) mercury by weight. 12,13 Carbon mercury loading can be monitored directly, or the mercury concentration in the exhaust at the outlet of the carbon bed can be monitored to
ensure the effectiveness of the carbon adsorber.

Some factors that can affect carbon bed adsorption efficiency include residence time of the gas in the carbon bed, carbon particle size, and exhaust stream moisture content. Longer residence times (a lower flow rate and larger carbon bed with more carbon mass increases the residence time) and smaller carbon particle sizes increase the mercury removal efficiency of the carbon bed. 10 Excessive water collection in a carbon filter will reduce control efficiency. Water can enter the pore structure of the carbon and block active adsorption sites, reducing the surface area available for mercury collection.



### Original Carbon Filter Control Design
In February 2008, the possibility of controlling all si x autoclaves at Goldstrike with carbon adsorption technology was investigated. To accommodate the specific conditions at Goldstrike, three different options were considered based on th e best information available at that time. As discussed below, since this initial investigation, further engineering of the add-on carbon adsorption filter control system has resulted in a more final design, which supersedes thes e original three control options. The three original control options are summarized below. In each option, the size of the carbon bed was primarily determined by the exhaust flow rate entering the bed (i.e., large flow rates re quire large beds to allow sufficient residence time).

Option 1 included installing an individual carbon f ilter at each of the stacks, modifying the existing venturi scrubbers to convert the mist eliminator portion into cooling towers, installing plate and frame heat exchangers at each scrubber, and installing on e mechanical draft cooling tower. Autoclave gas would be cooled at each scrubber tower and passed di rectly to a carbon filter. The cooled gas would have a lower flow rate and, although still saturate d, would contain less water, reducing the amount of water vapor entering the carbon filter. The carbon filter on Autoclave 1 would hold 7,140 pounds of carbon, the filter on Autoclaves 2 and 3 would hold 18,000 pounds of carbon, the filter on Autoclave 4 would hold 10,680 pounds of carbon, and the filter on Autoclaves 5 and 6 would hold 18,100 pounds of carbon. This option would require si gnificant structural modifications to install a carbon filter and heat exchanger at each scrubber tower; however, du ctwork would be minimi zed. Monitoring and
maintenance would be difficult at the elevation of th e towers. The operating complexity of running four heat exchangers and four carbon filters would also be much greater than a single condenser and carbon filter design. A flow diagram of Option 1 is shown as Figure 3.4, and the capital and annual operating
costs are shown in Table 3.3.Appendix 3, Page 16 Figure 3.4: Carbon Adsorption Option 1

Table 3.3: Capital and Annual Operating Costs of Option 1

Item Description Year of Quote Cost Capital Cost of the Carbon Adsorption Option 1 2007 $ 6,664,000 Operating Labor ($12.00/hr, 0.5 hr/shift, 2 shifts/day, 360 days/yr, 15% for supervision) 11 2007 $ 4,968 Maintenance Labor ($13.20/hr, 0. 5 hr/shift, 2 shifts/day, 360 days/yr) 11 2007 $ 4,752

Maintenance Materi als (100% of maintenance labor) 11 2007 $ 4,752 Utilities (at $0.09/kW-hr) 2007 $ 670,487 Indirect Annual Cost (including overhead, administration, taxes, and insurance) 11 2007 $ 275,243 Annual Operating and Maintenance Cost for Option 1 $ 960,202

Due to the saturated moisture content in the gas stream, it was uncertain if this option was viable. Three vendors were approached to provide a carbon adsorption filter estimate for the analysis. None had experience in treating saturated gas streams, especi ally with such high moisture levels. All were concerned that moisture condensing in the filter would negatively affect performance. Removal AUTOCLAVE 1 VENTURI SCRUBBER

COOLING TOWER CARBON ADSORBER

AUTOCLAVE 1

EXHAUST TO ATMOSPHERE

HEAT EXCHANGER

AUTOCLAVE 2/3 VENTURI SCRUBBER CARBON ADSORBER

AUTOCLAVE 2/3

EXHAUST TO ATMOSHPERE

HEAT EXCHANGER

AUTOCLAVE 5/6 VENTURI SCRUBBER CARBON ADSORBER

AUTOCLAVE 5/6

EXHAUST TO ATMOSPHERE

HEAT EXCHANGER AUTOCLAVE 4 VENTURI SCRUBBER CARBON ADSORBER

AUTOCLAVE 4

EXHAUST TO ATMOSPHERE

HEAT EXCHANGERAppendix 3, Page 17 efficiency, carbon life expectancy, and optimal filter design were all contingent on determining the effect of a high-moisture gas stream. Significant research an d testing was still needed to assess the viability of this option.

Option 1 required energy for the four heat ex changer recirculation pumps, two cooling tower recirculation pumps, and one cooling tower induced dr aft fan. Assuming 24 hours per day and 7 days per week operation, this equipm ent required approximately 7,450,000 kilowatt-hours per year (kWhr/yr) of energy.

Option 2 included installing one large carbon filter for all four autoclaves, one condenser, and one mechanical draft cooling tower. The autoclave gas from all four scrubbers would be ducted together to a condenser to cool the gas stream. The gas would then be reheated to raise the exhaust temperature above the dew point, reducing the risk of water condensing in the carbon filter. The exhaust would then pass through one 41,600 pound carbon filter. This opti on would require significant ductwork; however, the equipment would be accessible at ground level. This option tied the four autoclave gas streams together, which could cause flow complications. A flow diagram of Option 2 is provided as Figure 3.5, and the capital and annual operating costs are shown in Table 3.4.

Figure 3.5: Carbon Adsorption Option 2

AUTOCLAVE 1 VENTURI SCRUBBER

COOLING TOWER AUTOCLAVE 1

EXHAUST

AUTOCLAVE 2/3 VENTURI SCRUBBER

CARBON ADSORBER AUTOCLAVE 2/3

EXHAUST

TO ATMOSPHERE AUTOCLAVE 5/6 VENTURI SCRUBBER AUTOCLAVE 5/6

EXHAUST

AUTOCLAVE 4 VENTURI SCRUBBER AUTOCLAVE 4

EXHAUST

TO PROCESS TO PROCESS TO PROCESS TO PROCESS

CONDENSATE TO

PROCESS SEAL TANK ELECTRIC HEATERAppendix 3, Page 18 Table 3.4: Capital and Annual Operating Costs of Option 2

Item Description Year of Quote Cost Capital Cost of the Carbon Adsorption Option 2 2007 $ 10,133,000 Operating Labor ($12.00/hr, 0.5 hr/shift, 2 shifts/day, 360 days/yr, 15% for supervision) 11 2007 $ 4,968 Maintenance Labor ($13.20/hr, 0. 5 hr/shift, 2 shifts/day, 360 days/yr) 11 2007 $ 4,752
Maintenance Materi als (100% of maintenance labor) 11 2007 $ 4,752 Utilities (at $0.09/kW-hr) 2007 $ 620,142 Indirect Annual Cost (including overhead, administration, taxes, and insurance) 11 2007 $ 414,003 Annual Operating and Maintenance Cost for Option 2 $ 1,048,617

Option 2 required energy for the condensate pump, electric heater, two cooling tower recirculation pumps, and one cooling tower induced draft fan. Assuming 24 hours per day and 7 days per week operation, this equipment requires approximately 6,890,000 kW-hr/yr of energy.

Option 3 included installing one large carbon filter for all four autoclaves. The autoclave gas from all
four scrubbers would be ducted to gether and passed directly through the 164,000-pound carbon filter. The gas would not be cooled. The gas stream entering the carbon filter in this option would have the most water vapor of any of the options. Option 3 would require significant ductwork; however, the equipment would be accessible at ground level. This option tied the four autoclave gas streams together, which could cause flow complications. A flow diagram of Option 3 is provided as Figure 3.6, and the capital and annual operating costs are shown in Table 3.5.Appendix 3, Page 19 Figure 3.6: Carbon Adsorption Option 3

Table 3.5: Capital and Annual Operating Costs of Option 3

Item Description Year of Quote Cost Capital Cost of the Carbon Adsorption Option 3 2007 $ 6,505,000 Operating Labor ($12.00/hr, 0.5 hr/shift, 2 shifts/day, 360 days/yr, 15% for supervision) 11 2007 $ 4,968 Maintenance Labor ($13.20/hr, 0. 5 hr/shift, 2 shifts/day, 360 days/yr) 11 2007 $ 4,752
Maintenance Materi als (100% of maintenance labor) 11 2007 $ 4,752 Indirect Annual Cost (including overhead, administration, taxes, and insurance) 11 2007 $ 268,883 Annual Operating and Maintenance Cost for Option 3 $ 283,355

Option 3 did not require any energy in addition to the current energy requirements. However, as with Option 1, it was uncertain if this option was viable due to the very high moisture content in the gas stream. Significant research and testing was still needed to assess the viability of this option.

For all of the options, it was assumed that the autocl aves would provide sufficient pressure so that fans would not be required to push or pull the exhaust through the carbon filter(s). AUTOCLAVE 1 VENTURI SCRUBBER

COOLING TOWER AUTOCLAVE 1

EXHAUST

AUTOCLAVE 2/3 VENTURI SCRUBBER

CARBON ADSORBER AUTOCLAVE 2/3

EXHAUST

TO ATMOSPHERE AUTOCLAVE 5/6 VENTURI SCRUBBER AUTOCLAVE 5/6

EXHAUST

AUTOCLAVE 4 VENTURI SCRUBBER AUTOCLAVE 4

EXHAUST

TO PROCESS TO PROCESS TO PROCESS TO PROCESS

CONDENSATE TO

PROCESS SEAL TANK ELECTRIC HEATERAppendix 3, Page 20 

### Alkaline Autoclaving Control Design Update
Since February 2008, Goldstrike has continued to develop the engineering of an add-on carbon adsorption filter control option. The latest engineering analysis was conducted for the alkaline mode of operation for Autoclaves 4 through 6 (see June 2010 Phase-2 Application). In March 2010, mercury stack
test data indicated that the mercur y emissions from processing ore under alkaline conditions are higher than the emissions from acidic autoclaving. (T esting was authorized by NDEP pursuant to NAC 445B.232.) The additional controls for Autoclaves 4 through 6 were engineered based on this higher mercury emission data.

The engineering analysis for Autoclaves 4 through 6 determined that gas conditioning, to prevent condensation in the filter, would be necessary upstream of any carbon filter. This updated design analysis of an add-on carbon adsorption filter cont rol eliminated the original Options 1 and 3 as viable control options due to the unavoidable water conden sation problem inherent to these options. The updated design also resolved the combined exhaust flow problem inherent to the original Option 2, but it determined that the gas conditioning equipment in Option 2 was grossly under-sized, under-engineered, and under-budgeted.

The June 2010 Phase-2 Application for the alkaline mode of operation for Autoclaves 4 through 6 proposed an add-on carbon adsorpti on filter control with upstream gas conditioning (alkaline control system). This control system is designed to remo ve water (and Hg) from the gas stream prior to the carbon adsorption filter. The equi pment upstream of the carbon filter consists of a secondary venturi scrubber, a scrubber mist eliminator, a gas cooling tower, a condenser, a refrigeration unit for the condenser, a wet gas separator, a hu midity control heater, and a water cooling tower. The water cooling tower provides cooling water for the scrubber mist eliminator, gas cooling tower, and refrigeration unit. The heater is located downstream of the wet gas se parator and raises the exhaust temperature above the dew point prior to entering the carbon bed. Figure 3.7 provides a flow diagram of the alkaline control system (without the water cooling tower, refrigeration unit, and heater shown).Appendix 3, Page 21 Figure 3.7: Alkaline Control System

Although the engineering for the alkaline control sy stem has not been finalized, preliminary design specifications and cost data were obtained from Ak er Solutions. Based on this preliminary data, the carbon adsorption filter will contain 12,000 pounds of carbon in the primary bed and 28,800 pounds of carbon in the secondary bed, for a total of 40,800 pounds of activated sulfur-impregnated carbon. The controls are designed so that the exhaust flow ra te through the carbon filter is expected to be approximately 15,500 acfm. Based on this flow rate, the residence time would be approximately 1.2 seconds in the primary bed and 2.8 seconds in the secondary bed, for a total residence time of 4 seconds. Appendices A through D provide the general arra ngement, piping and instrumentation diagrams, process flow diagrams, and process de sign criteria for the alkaline cont rol system. Estimated capital and annual operating costs for the alkaline control system are provided in Table 3.6.Appendix 3, Page 22 Table 3.6: Capital and Annual Operating Costs of the Alkaline Control System

Item Description Cost Basis Capital Costs Engineering Costs $ 3,506,350 2010 estimate Material Costs $ 13,219,950 2010 estimate Labor Costs $ 11,583,070 2010 estimate Barrick Project Support $ 977,500 2010 estimate Total Capital Costs $ 29,286,870 2010 estimate
Annual Operating Costs Operating Labor (4 operators at $90,000/yr) $ 360,000 Per year Maintenance Labor (1 maintenance at $90,000/yr) $ 90,000 Per year Maintenance Supplies $ 533,774 Per year Utilities ($0.08/kW-hr) $ 911,129 Per year Consumables (replacement carbon, reagents and flocculants, cooling tower treatment chemical) $ 251,550 Per year

Total Annual Operating Costs $ 2,146,453 Per year

The alkaline control system requires energy fo r the venturi scrubber variable throat, venturi scrubber/scrubber mist eliminator pump, gas coolin g tower pump, condensate pump, effluent pump, refrigeration unit, booster fan, cooling tower fans, cooling tower pumps, and humidity control heater.
The maximum annual estimate of to tal energy required for these units, assuming 24 hours per day and 7 days per week operation is 11,389,107 kW-hr/yr. As shown in Table 3.6, assuming an electricity cost of 8 cents per kW-hr, the total energy cost is $911,129 per year.

Before the sulfur-impregnated carbon in the carbon filter reaches the maximum carbon loading capacity, it will need to be replaced. The new carbon and each carbon replacement will cost approximately $82,800. In addition, disposal costs of spent carbon are approximately $2.50 per pound of carbon 14 or $100,000 per replacement.

Non-air quality health, environmental, and energy impacts are associated with the alkaline control system. The control system will increase energy use du e to the additional fans and pumps, as well as the energy required to cool the exhaust stream and run th e refrigeration unit. The total heat duty of the alkaline control system includes the latent heat of condensing the water vapor and the specific heat of cooling the exhaust stream. The alkaline control system has a total heat duty of 190 MMBtu/hr.

The alkaline control system also causes non-air qu ality health and environmental impacts due to the increased water use by the additional controls and th e recirculation of water by the cooling tower. The
water condensed from the exhaust stream must be treate d and reused to offset the additional water input.
The water that is not recirculated in the cont rols must be sent to water treatment.Appendix 3, Page 23 Furthermore, the shipping and reclamation of th e spent carbon and elemental mercury has non-air quality health, environmenta l, and energy impacts.



### Acidic Autoclaving Control Design Update
Based on the engineering design of the alkaline contro l system for Autoclaves 4 through 6, Goldstrike has investigated the possibility of using a similar cont rol system for the acidic mode of operations at Autoclaves 1 through 3. Because of the high moistu re content in the exhaust streams from Autoclaves 1 through 3, gas conditioning (similar to the alkaline control system) would be ne cessary upstream of any carbon filter. Unlike the alkaline operation of Auto claves 4 through 6, the mercury concentration in the exhaust from Autoclaves 1 through 3 is so low that mercury condensation upstre am of the carbon bed is not practical (see Condenser discussion below).

The add-on carbon adsorption filter control option fo r Autoclaves 1 through 3 includes one carbon filter (two beds) for all three autoclaves with upstream gas conditioning for water removal (acidic control system). The equipment upstream of the carbon f ilter consists of a seco ndary venturi scrubber, a scrubber mist eliminator, a gas cooling tower, a wet ga s separator, a humidity control heater, and a water cooling tower. The water cooling tower provides co oling water for the scrubber mist eliminator and gas cooling tower. The heater is located downstream of the wet gas separator and raises the exhaust temperature above the dew point prior to entering the ca rbon bed. Figure 3.8 provides a flow diagram of the acidic control system (without the water cooling tower shown).

Figure 3.8: Acidic Control System

Autoclave #1

S2.015 Secondary

Venturi Scrubber

Scrubber Mist Eliminator Gas Cooling Tower Wet Gas Separator Carbon Filter Booster Fan

Autoclave #1

Primary Venturi Scrubber

Autoclave #3 S2.017 Autoclave #2

S2.016 Autoclave #2

Primary Venturi Scrubber Autoclave #3 Primary Venturi Scrubber To Atmosphere Humidity Control Heater Purge AirAppendix 3, Page 24 Due to the low mercury concentration in the exhaust stream, a wet gas condenser and a refrigeration unit are not included in the acidic control system. In addi tion, the exhaust flow rate from the acidic operation of the autoclaves is lower than from the alkaline operat ion; therefore, the exhaust flow rate to the carbon bed in the acidic control system would be approximately 54% lower than the exhaust flow rate in the alkaline control system.

Although the engineering for the acidic control sy stem has not been finalized, preliminary design specifications and cost data were obtained from Ak er Solutions. Based on this preliminary data, the carbon adsorption filter will contain 6,600 pounds of carbon in the primary bed and 15,800 pounds of carbon in the secondary bed, for a total of 22,400 pounds of activated sulfur-impregnated carbon. The exhaust flow rate through the carbon filter is expect ed to be approximately 8,500 acfm. Based on this flow rate, the residence time would be approximately 1.2 seconds in the primary bed and 2.8 seconds in the secondary bed, for a total residence time of 4 seconds.

The general arrangement, piping and instrumentat ion diagrams, and process flow diagrams for the alkaline control system provided in Appendices A thro ugh C are also generally applicable to the acidic control system. However, there are some differences in the acidic control system, such as lower mercury
concentration in the exhaust and no conden ser and associated refrigeration unit.

Estimated installation and operating costs for the acidic control system are provided in Table 3.7. Operating costs, except carbon replacement and re clamation costs, were estimated from the alkaline control system costs (shown in Table 3.6) using the ratio of the total installed cost for the alkaline control system to the total installed cost for the acidic control system (i.e., $18,600,000/$29,290,000 = 63.5%). Carbon replacement and reclamation costs are based on 22,400 pounds of carbon.

Table 3.7: Installation and Operating Costs of the Acidic Control System

Item Description Cost Basis

Installation Costs $18,600,000 2010 Estimate Operating Costs Operating Labor and Overhead $229,000 Per year
Maintenance Labor and Overhead $57,000 Per year Maintenance Supplies $339,000 Per year Utilities ($0.08/kW-hr) $579,000 Per year Carbon Replacement/Reclamation $100,800 Per replacement Consumables (reagents and flocculants, cooling tower treatment chemical) $107,000 Per year

The acidic control system requires energy for the venturi scrubber variable throat, venturi scrubber/scrubber mist eliminator pump, gas cooling tower pump, effluent pump, booster fan, cooling tower fans, cooling tower pumps, an d humidity control heater. The ma ximum annual estimate of total energy required for these units, assuming 24 ho urs per day and 7 days per week operation isAppendix 3, Page 25approximately 7,233,000 kW-hr/yr. As shown in Table 3.7, assuming an electricity cost of 8 cents per kWhr, the total energy cost is $579,000 per year.

Before the sulfur-impregnated carbon in the carbon filter reaches the maximum carbon loading capacity, it will need to be replaced. The new carbon and each carbon replacement will cost approximately $44,800. In addition, disposal costs of spent carbon are approximately $2.50 per pound of carbon 14 or $56,000 per replacement.

Non-air quality health, environmental, and energy impa cts are associated with th e acidic control system. The control system will increase ener gy use due to the additional fans and pumps, as well as the energy required to cool the exhaust stream. The total heat du ty of the acidic control system includes the latent heat of condensing the water vapor and the specific he at of cooling the exhaust stream. The acidic control system has a total heat duty of 101 MMBtu/hr.

The acidic control system also causes non-air qu ality health and environmental impacts due to the increased water use by the additional controls and th e recirculation of water by the cooling tower. The acidic control system will require 240 gallons per minute (gpm) of additional fresh water. The control system will also require shipping and reclamation of the spent carbon , which has non-air quality health and environmental impacts.



### Activated Carbon Injection
Activated carbon injection is similar to activated carbon filters in that activated carbon particles are used to adsorb mercury from the gas stream. With carbon injection, the carbon particles are injected directly into the gas stream where they adsorb mercury and ar e then collected in downst ream particulate controls such as baghouses, wet scrubbers, or wet ESPs. As wi th activated carbon filters, the control effectiveness of activated carbon injection will be limited if water enters the activated adsorption sites. There is no precedent for using the carbon injection technology on gas streams with high moisture content as in the case of the Goldstrike autoclaves. In addition, the co ntrol efficiency for carbon injection is typically lower than for carbon beds. Therefore, the appropriate application of the activated carbon technology for autoclaves is a carbon adsorption filter.



### Selenium Filters

Selenium filters are similar to selenium scrubbers in that they use selenium to react with the elemental mercury in the gas stream to form mercuric seleni de. Selenium filters use a selenium-impregnated porous carrier structure which is housed in a cylindrical tower. The selenium filter’s maximum operating temperature is approximately 250  ̊ F. The filters require a dry gas st ream because water will degrade the filter media. This provides a significant limitation to its application for the Goldstrike autoclaves. The typical filter carrying capacity is between 10 and 15 percent mercury by weight.

There are only a few installations of selenium filters in the world, primarily in Sweden, and there is no operating data from these applications. Selenium f ilters are expensive to produce and to regenerate.Appendix 3, Page 26 There is no basis to believe that selenium filters wo uld provide a better alternative than activated carbon. In addition, there is some concern that th e filters cause selenium air emissions.



### Condensers
Condensers control mercury by cooling a gas stream and causing the elemental mercury to condense. In order for condensation to occur with a drop in te mperature, the gas stream must be saturated with mercury vapor. Mercury saturation is determined by the mercury saturation pressure curve as shown
below.

Figure 3.9: Mercury Saturation Pressure Curve 15

As shown by Table 3.1, the concentration of mercury in the exhaust from the autoclaves at Goldstrike (operating in acidic mode) ranges from 2.01x10 -5 to 3.05x10 -4 gr/dscf. This concentration is below the mercury saturation concentration even if the gas stream is cooled to 32  ̊ F. (The saturated mercury

concentration at 32  ̊ F is approximately 9.7x10 -4 gr/dscf. 15 ) Therefore, mercury condensation is not an effective control technology for the autoclaves at Goldstrike.



### Other Work Practices
As discussed above, mercury stack testing conducted in March 2010 indicated that the mercury emissions from acidic autoclaving are significantly less than th e emissions from alkaline au toclaving. (Testing was authorized by NDEP pursuant to NAC 445B.232.) By allowing only acidic autoclaving ore to be processed by Autoclaves 1 through 3, the mercury emis sions from these autoclaves can be minimized. 0.000 0.005 0.010 0.015 0.020 0.025 0.030

30 50 70 90 110 130 150 170 190 Temperature (F)Vapor Pressure (kPa)Appendix 3, Page 27 All of the autoclaves treat single refractory ores by oxidizing sulfides to sulfates. Sulfides that are present in the slurry can encapsulate the gold in sulfide matr ices, making it unavailable to cyanide leaching. In acidic autoclaving, carbonates in the ore slurry re act with sulfuric acid in the acidulation tanks and
release carbon dioxide. If the ore slurry has too high of a percentage of carbonates, then acidulation with sulfuric acid is not viable, and the ore is processed with alkaline autoclaving. To ensure the processing of only acidic autoclaving ore, the carbonate/sulfid e ratio of the ore slurry can be monitored.

In addition, using autoclaves in an acidic mode of operation to oxidize ore is an inherently lower mercury emitting process. Based on 2007 mercury testing of the post-venturi scrubber emissions at Goldstrike, mercury volatilization by the autoclaves operating in an acidic mode is extremely low. As shown in Table 3.8, the average mercury volatilization is approximately 0.02 percent.

Table 3.8: Acidic Autoclaving Mercury Volatilization

Source Hg Throughput lb/hr Hg Emissions lb/hr Hg Volatilization

percentage
Autoclave 1 4.17 0.00112 0.027
Autoclave 1 3.58 0.00308 0.086
Autoclaves 2 and 3 10.06 0.00074 0.007
Autoclaves 2 and 3 8.62 0.00086 0.010
Autoclave 4 4.76 0.00018 0.004
Autoclaves 5 and 6 8.56 0.00137 0.016
Autoclaves 5 and 6 10.05 0.00069 0.007 Average 0.022Appendix 3, Page 28 

### Part III - Proposed NvMACT
Per NAC 445B.3675.1.(a), th e applicant must propose “ standards, methods of control or other limitations to be applied to the thermal unit for the reduction of mercur y emissions that the applicant deems sufficient for the Director to determine to be NvMACT for the thermal unit that emits mercury .” Therefore, the NvMACT proposed in this part follows the criteria that are required by the Director pursuant to NAC 445B.3677.3(b). All items considered in this NvMACT analysis are checked in the criteria list provided
below:

NAC 445B.3677 Review of and action on application fo r tier-1 or tier-2 thermal unit that emits mercury.

3.(b) Make a determination of NvMACT for the thermal unit that emits mercury in which the Director shall consider the following for each thermal unit that emits mercury:
(1) The maximum degree of reduction of mercury emi ssions that is achievable for the thermal unit after considering:
(I) The cost of achieving such a reduction; and

(II) Consistent with section 112(d)(2) of the Act, any nonair quality he alth and environm ental impacts and energy requirements for each method or technology to control mercury emissions from the thermal unit that emits mercury to implement the NvMACT.

(2) The measures that reduce the volume or eliminate mercury emissions through process changes, substitution of materials or any other modifications.
(3) The enclosure of systems or pr ocesses to eliminate mercury emissions.
(4) The collection, capture or treatment of mercury emissions.
(5) The design, equipment, work practice or operation al standards of the thermal unit that emits mercury, including, without limitation, the requirements for trai ning and certification of operators of the thermal unit that emits mercury.
(6) The differences in the age, remaining operating life and configurations of similar thermal units that emit mercury. The Director may also consider the differences in the concentration of mercury in the ore, size and any other relevant factors of the simila r thermal units that emit mercury.

As discussed in Part I, the control technology currently installed on autoclaves at precious metal mining facilities in Nevada is a venturi scrubber. Of the other possible control options, discussed in Part II, the carbon adsorption filter is the most potentially viable option. The carbon adsorption filter control option is sized at 22,400 pounds and would require upstre am gas conditioning to remove the water from the exhaust stream. The gas conditioning equipment incl udes: a secondary venturi scrubber, a scrubber mist eliminator, a gas cooling tower, a wet gas separator, a humidity control heater, and a water cooling tower.

The estimated control efficiency of the carbon filter in the acidic control system (after gas conditioning to remove water) is 95 percent or greater for elementa l mercury, 50 percent for oxidized mercury, and 25 percent for particulate mercury. Th erefore, it is expected that over 91 percent of the total mercury entering the carbon filter will be removed. The acidic control system is not expected to get any controlAppendix 3, Page 29 efficiency from mercury condensation in the gas cond itioning equipment, as the mercury concentration is below the saturated vapor pressure, even at 32  F. However, due to the mois ture in the exhaust, the gas conditioning equipment is necessary for proper operat ion of the downstream carb on adsorption filter. The total amount of mercury emissions available for removal from Autoclaves 1 through 3 is shown in
Table 3.9.

Table 3.9: Annual Mercury Emissions from Acidic Operation of Autoclaves 1 through 3

Autoclave 2007 2008 2009
Autoclave 1 8.9 8.0 3.9
Autoclaves 2 and 3 6.3 13.0 6.2
Total 15.2 21.0 10.1

Emissions based on stack testing during acidic op eration and total annual hours of operation.

As shown by Table 3.9, the amount of mercury emissions available for control ranges from 10.1 to 21.0 pounds per year. Therefore, the achievable reduction in mercury emissions by the acidic control system is less than 10.1 to 21.0 pounds per year.



### Analysis of NvMACT Criteria 445B.3677.3(b)(1)(I) – The Cost of Achieving Mercury Emissions Reduction
The cost of achieving mercury reduction is typically vi ewed on a cost-benefit basis described as the cost effectiveness of the controls. In this case, the cost is the annualized cost of installing and operating the control system and the benefit is the annual reduction of mercury emissions (i.e., the lower the cost and the higher the mercury emission reduction, the greate r the cost effectiveness). The cost to install and operate the acidic control system is provided in Table 3.10.

Operating costs, except carbon replacement and re clamation costs, were estimated from the alkaline control system costs (shown in Table 3.6) using the ratio of the total installed cost for the alkaline control system to the total installed cost for the acidic control system (i.e. $18,600,000/$29,290,000 = 63.5%). Carbon replacement and reclamation costs are based on 22,400 pounds of carbon.Appendix 3, Page 30 Table 3.10: Installation and Operating Costs of the Acidic Control System

Item Description Cost Basis

Installation Costs $18,600,000 2010 Estimate Operating Costs Operating Labor and Overhead $229,000 Per year
Maintenance Labor and Overhead $57,000 Per year Maintenance Supplies $339,000 Per year Utilities ($0.08/kW-hr) $579,000 Per year Carbon Replacement/Reclamation $100,800 Per replacement Consumables (reagents and flocculants, cooling tower treatment chemical) $107,000 Per year



### Annualized Cost
To annualize the costs presented in Table 3.10, on e must account for the costs and benefits of the investment over a period of time rather than at the moment of purcha se. Consequently, several assumptions must be made. These assumptions include the useful life of the equipment and the interest rate to estimate the time value of money.

Useful Life:

The useful life of both the autoclaves and the acidic control system are an important aspect of the
annualized cost. The autoclaves at Goldstrike have a limited supply of ore th at can be processed under acidic conditions. Goldstrike has proposed to oper ate Autoclaves 4 through 6 under alkaline conditions to extend the life of these autoclaves. However, Au toclaves 1 through 3 are expected to run out of ore that can be processed under acid co nditions in the near future.

The exact date that Autoclaves 1 through 3 will run ou t of feed stock cannot be determined at this time. However, Autoclave 1 has already been shut down for all of 2010 due to the limited feed stock. The
current assessment of ore reserves estimates that the autoclaves have a 6- to 12-month supply of ore that can be processed under acidic conditions. This time frame could be extended to 2 years if Autoclaves 4 through 6 are allowed to process ore under alkaline conditions (i.e., all ore that can be processed under acidic conditions would then be reserved for Autoclaves 1 through 3). However, these time frames are wholly dependent on known ore reserves. Exploration and ore characteristic analyses continue, which
could reveal additional ore reserves then are currentl y known. Thus, the annualized cost provided herein
is based on an autoclave life range of 2 or more years.

Because of the limited feed stock, the useful life of th e acidic control system is expected to exceed that of the autoclaves. In addition, the carbon beds are expected to last the life of the autoclaves. The beds have been sized to handle the large exhaust flow rate of the autoclaves in order to provide adequate residence time of the exhaust stream; approximately 1.2 seconds on the primary bed and 2.8 seconds on theAppendix 3, Page 31 secondary bed. At the low mercury loading rates, these beds are not expected to reach their mercury loading capacity during the life of the autoclaves . (i.e., The mercury emissions from Autoclaves 1 through 3 have averaged approximately 15 pounds per year during acidic operations. At 22,400 pounds of carbon, with a loading capacity of at least 15 percent, the theoretical life of the carbon is over one hundred years.)

As discussed above, the useful life of the acidic cont rol system is expected to be limited by the life of Autoclaves 1 through 3. Therefore, the annualized cost analysis is based on a minimum life of 2 years and a maximum life of more than 2 years. Becaus e the maximum number of ye ars Autoclaves 1 through 3 will operate cannot be determined at this ti me, the longest period provided in Table A.2, Capital Recovery Factors for Equal Payments on a Dollar over a Number of Years , of the EPA Control Cost Manual 16 of 25 years is used to provide a conservative ly low estimate of the annualized cost.

Interest Rate:

The annualized cost requires an assumed interest rate to estimate the time value of money. According to the EPA Control Cost Manual, types of rates include: th e rate of return a firm can obtain by investing, the rate at which it can borrow money, the real interest rate , and the social interest rate. In order to define the possible of range of annualized costs, the rang e of interest rates provided in Table A.2, Capital Recovery Factors for Equal Payments on a Dollar over a Number of Years , of the EPA Control Cost Manual of 5.5 percent to 15 percent is used. Because the rate of return a firm can obtain by investing can be greater than 15 percent, this range of rates provides a conser vatively low estimate of the annualized cost.

Annualized Cost:

The annualization of the costs presented in Table 3.10 fo r the ranges of the useful life and the interest rate are provided in Table 3.11. As shown in this table, th e annualized cost of the acidic control system ranges from $2,702,000 per year (at 25 years and 5.5 percent) to $12,786,000 per year (at 2 years and 15 percent).

Table 3.11: Annualized Installation and Operating Costs of the Acidic Control System Annualized Costs ($/Year) Item Description At 25 years; 5.5% At 2 years; 15% Installation Costs Capitol Recovery $ 1,387,000 $ 11,441,000 Operating Costs Operating Labor and Overhead $ 229,000 $ 229,000 Maintenance Labor and Overhead $ 57,000 $ 57,000 Maintenance Supplies $ 339,000 $ 339,000 Utilities ($0.08/kW-hr) $ 579,000 $ 579,000 Carbon Reclamation $ 4,000 $ 34,000 Consumables (reagents and flocculants, cooling tower treatment chemical) $ 107,000 $ 107,000

Total Annualize d Costs $ 2,702,000 $ 12,786,000Appendix 3, Page 32 

### Mercury Emission Reduction
As shown in Table 3.9 above, actual emissions from Autoclaves 1 through 3 have ranged from 10.1 to 21.0 pounds per year for the last three years. Therefore, the achievable reduction in mercury emissions by the acidic control system is less than 10.1 to 21.0 poun ds per year. However, for the purposes of determining an absolute low cost effectiveness value, the th eoretical maximum achievable reduction in mercury emissions may be calculated by assuming all three autoclaves operating at the maximum emission rate for 8,760 hours per year.

The maximum emission rate is calculated by multip lying the maximum mercury emission concentration, prior to the acidic control system, by the maximum co mbined exhaust flow rate for Autoclaves 1 through
3. The maximum emission concentration is estimated at 4.0x10 -4 grain per dry standard cubic foot (gr/dscf). See the section titled, Proposed Mercury Emission Limit , at the end of this Part. The maximum combined exhaust flow rate is 7,500 dry standard cubic feet per minute (dscfm). See Appendix 1. Multiplying these values together and by 8,760 hours per year yields 225.3 pounds of mercury per year.



### Cost Effectiveness
Table 3.12 provides the range of cost effectiveness of the acidic control system for Autoclaves 1 through 3. Note that because this analysis requires several assu mptions as discussed above, a range is presented so that the upper and lower limits of the assumptions are accurately defined.

Table 3.12: Cost Effectiveness of the Acidic Control System Cost Effectiveness ($/lb) Item Description At 25 years; 5.5% At 2 years; 15% Actual Mercury Reduction of 21.0 lb/yr $ 129,000 $ 609,000 Theoretical Maximum Mercury Reduction of 225.3 lb/yr $ 12,000 $ 57,000



### 445B.3677.3(b)(1)(II) – Non-air Quality Health and Environmental Impacts and Energy Requirements
The acidic control system, consisting of the carbon adsorption filter and up stream gas conditioning equipment, would cause increased energy requiremen ts. The control system would increase energy use
due to the additional venturi scrubber variable thro at, venturi scrubber/scrubber mist eliminator pump, gas cooling tower pump, effluent pump, booster fan, cooling tower fans, cooling tower pumps, and humidity control heater. The maximum annual esti mate of total energy required for these units, assuming 24 hours per day and 7 days per week op eration is 7,233,000 kW-hr/yr. Part of the energy required by the acidic control system is the energy to cool the exhaust stream. The total heat duty of the acidic control system includes the latent heat of condensing the water vapor and the specific heat of cooling the exhaust stream. The acidic control system has a total heat duty of 101 MMBtu/hr.

The acidic control system also causes non-air qu ality health and environmental impacts due to the increased water use by the additional controls and th e recirculation of water by the cooling tower. The acidic control system will require 240 gallons per minute (gpm) of additional fresh water. The controlAppendix 3, Page 33 system will also require shipping and reclamation of the spent carbon , which has non-air quality health and environmental impacts.



### 445B.3677.3(b)(2) – Process Changes or Substituti on of Materials to Reduce Mercury Emissions
Autoclaves 1 through 3 only operate under an acidic mode of operations and only process acidic autoclaving ore. As indicated by the March 2010 stack testing at Goldstrike, mercury emissions from acidic autoclaving are significantly lower than alkalin e autoclaving. Therefore, processing only acidic autoclaving ore minimizes mercury emissions. In a ddition, acidic autoclaving is an inherently low mercury emitting process, as only 0.02 percent of the mercury entering the autoclaves in volatilized. (See Table 3.8).



### 445B.3677.3(b)(3) – Enclosure of Systems or Processes to Eliminate Mercury Emissions
The existing venturi scrubber controls are designed so that all emissions from Autoclaves 1 through 3 are captured and ducted to the venturi scrubbers. There ar e no additional enclosures that could be added to eliminate mercury emissions.



### 445B.3677.3(b)(4) – Collection, Capture or Treatment of Mercury Emissions
Mercury collection through condensation is not an effective method to reduce mercury emissions from autoclaves operating in acidic mode. The mercury concentration in the exhaust stream is below the mercury saturation concentration even if the gas stream is cooled to 32  ̊ F. As shown by the stack tests in Table 3.1, the maximum concentration of mercury in the exhaust from the autoclaves at Goldstrike (operating in acidic mode) is 3.05x10 -4 gr/dscf.

The carbon adsorption filter would capture mercury as carbon loaded with mercury. Once the sulfurimpregnated carbon in the carbon filter reaches the maximum carbon loading capacity, it would be replaced by new carbon. The carbon loaded with merc ury that is removed from the filter would need to
be sent off-site for reclamation.



### 445B.3677.3(b)(5) – Design, Equipment, Work Practice, or Operational Standards of the Thermal Unit
As discussed above, by allowing only acidic autoclaving ore to be processed by Autoclaves 1 through 3, the mercury emissions from these autoclaves can be minimized. If the ore slurry has too high of a percentage of carbonates, then acidulation with sulfuric acid is not viable, and the ore is processed with alkaline autoclaving. To ensure the processing of only acidic autoclaving ore, the carbonate/sulfide ratio of the ore slurry can be monitored.



### 445B.3677.3(b)(6) – Differences in Age, Remaining Operating Life, Configurations, Ore Mercury Concentration, Size, and Any Other Relevant Factors of the Similar Thermal Units
The autoclaves at Goldstrike have a limited supply of ore that can be autoclaved. The ore that is currently being processed is increasingly carbonaceous. Due to this increase of carbonates in the ore, the amount of ore that can be processed with acidic autoclav ing is limited. If Goldstrike is not able to permit Autoclaves 4 through 6 for alkaline autoclaving, it is estimated that the remaining acidic ore will run out in six to twelve months (with all autoclaves processi ng the acidic ore). If Autoclaves 4 through 6 areAppendix 3, Page 34 converted to an alkaline mode of operations, the remaining acidic ore is expected to run out in approximately two years (with Autoclaves 1 through 3 primarily processing the acidic ore). Unless additional processing techniques or ore reserves are discovered, by the end of 2012, Autoclaves 1 through 3 are expected to be shut down.



### Proposed NvMACT
After considering the inherently low mercury emissions of the acidic autoclaving process; the cost and energy, water, and disposal requirem ents of the carbon filter and upst ream gas conditioning equipment; the reduction of mercury emissions through only processing acidic autoclaving ore; and the remaining operating life of Autoclaves 1 through 3, Goldstrike has concluded that the add-on carbon adsorption filter control with upstream gas co nditioning (acidic control system) do es not meet NvMACT. Therefore, based on the existing control technologies and work practices described in Part I and the additional control technology options described in Part II, Goldst rike proposes that the venturi scrubbers currently installed on Autoclaves 1 through 3 and the following work practices are NvMACT:

 maintaining the pressure drop for each venturi scrubber at or below 70 inches of water,

 maintaining the water flow rate for each venturi scrubber at or above 50 gallons per minute,
and

 maintaining the carbonate/sulfide ra tio of the ore slurry below 3.

At Goldstrike, there is a dedicated venturi scrubber fo r each autoclave. Autoclave 1 exhausts to its own stack, and Autoclaves 2 and 3 exhaust to a shared stack.

For each venturi scrubber, the pressure drop across the scrubber is monitored daily. The pressure drop for each scrubber is maintained at or below 70 inches of water; however, due to the design of the scrubbers, the pressure drop is typically much lower. At Goldstrike, in order to prevent steam loss for the autoclave vessel and the high pressure splash ve ssel, the release valves on these vessels are kept closed as much as possible. By limiting the release of steam from the autoclave and high pressure splash vessels, the autoclave system can operate more efficientl y by requiring less heat input. Due to the small amount of off-gas passing through the scrubber, th e pressure before the sc rubber is typically low, resulting in a small drop in pressure across the sc rubber. For these venturi scrubbers, a low pressure drop is an indication of low emissions because it occurs when there is little or no exhaust from the autoclave and high pressure splash vessels. The syst em is designed so that all the emissions from the autoclaves are captured and ducted through the venturi scrubbers.

Water flow rate is also monitored daily and is kept at or above 50 gallons per minute. For the scrubbers at Goldstrike, a flow rate of at least 50 gallons per minute allows for sufficient coverage of the scrubber throat and creates sufficient collection targets. The scrubber water is pumped to each venturi scrubber by the water feed pump. Each scrubber has an isolation va lve to stop scrubber water flow if an autoclave is not operating. The scrubber water is pumped from each venturi scrubber by scrubber underflow pumps. Each scrubber has one underflow pump.Appendix 3, Page 35 The venturi scrubbers require energy for the water feed pump and each scrubber underflow pump. The maximum annual estimate of total energy required fo r these units, assuming 24 hours per day and 7 days per week operation is approximately 474,000 kilowatt-hours per year (kW-hr/yr). 17

, 18

The carbonate/sulfide ratio of the ore slurry feed to Autoclaves 1 through 3 will be monitored each shift and kept below 3. By maintaining the carbonate/sulfide ratio below 3, Autoclaves 1 through 3 will only be able to process acidic autoclaving ore, which will minimize mercury emissions from these autoclaves.



### Proposed Mercury Emission Limit
Goldstrike proposes to establish a final NvMACT emis sion limit for Autoclaves 1 through 3 based on the Nevada Mercury Control Program's (NMCP) True-U p/True-Down (TUTD) meth odology. The final
NvMACT limit would be established based on si x Method 29 stack tests during a three-year demonstration period. The proposed "interim NvMACT " emission limit for Autoclaves 1 through 3, each,

is 4.0x10 -4 gr/dscf. This interim limit was determined from the average of all the Goldstrike source tests provided in Table 3.1 (all tests are for Autoclaves 1 through 6 while operating in acidic mode) plus three standard deviations. This calculation method (shown on page 3 of Appendix 2) accounts for limited test data as well as stack testing and operational variability.Appendix 3, Page 36 

# ENDNOTES

1 Nevada Division of Environmental Protection, Bureau of Air Quality Planning. Nevada Mercury Control Program (NMCP) – NvMACT Cl earinghouse. Phase-2 Applications . 2008. http://ndep.nv.gov/BAQP /hg/clearinghouse.html

2 Rong Yan et al. “Bench-scale experimental evaluation of carbon performance on mercury vapour adsorption.” Fuel . Vol. 83, No. 17-18, 2004, p. 2402.

3 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Control Cost Manual , 6 th ed. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. 2002. Section 6, Chapter 2 – Wet Scrubbers for Particulate Matter.

4 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Training Institute (APTI) SI:412C Scrubber Systems Operation Review . Lesson 2, 1998.

5 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Training Institute (APTI)SI:412C Scrubber Systems Operation Review . 1998. Lesson 3.

6 Nevada Division of Environmental Protection, Bureau of Air Quality Planning. Nevada Mercury Control Program (NMCP) – NvMACT Clearinghouse. Mercury Emissions Management System (MEMS) . 2010. http://www.ndep.nv.gov/baqp/search

7 Nevada Division of Environmental Protection, Bureau of Air Pollution Control. Precious Metals Mining Mercury Air Emissions Questionnaires . 2006.

8 2006 OHM Test Data for Tier-1 Units . Nevada Mercury Control Program (NMCP) Data Site. http://ndep.nv.gov/bapc/mercury/

.

9 TRC Environmental Corp. Final Report - Emissions Compliance Demonstration for Systems 18, 19, 61, and 66 (Class I Operating Permit No. AP1041-0739.01) - September 2007 . September 2, 2007.

10 Booz Allen & Hamilton Inc. Report prepared for U.S. EPA Region 9. Mercury Mass Balance and Emission Factor Estimates for Gold Ore Processing Facilities (Draft) , U.S. EPA Region 9. January 14, 2001.

11 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Control Cost Manual , 6 th ed. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. 2002. Section 3.1, Chapter 1 – Carbon Adsorbers.

12 Scotia International of Nevada, Inc. Product Bulletin COL-IS 60 Coal Based Activated Carbon Impregnated with Sulfur

.Appendix 3, Page 37 13 Michael G. Klett, Russell C. Maxwell, and Mich ael D. Rutkowski. Parsons Infrastructure and Technology Group Inc. Report prepared for the Un ited States Department of Energy National Energy Technology Laboratory. The Cost of Mercury Removal in an IGCC Plant Final Report . September 2002.

14 Cole, Andy. Environmental Manger, Barrick Goldstrike Mines, Inc. [Communication with K. Lewis, Air Sciences Inc.]. January 23, 2008.

15 Taylor and Francis Group. CRC Handbook of Chemistry and Physics , 86 th Ed. New York. 2005, p. 6-126.

16 United States Environmental Pr otection Agency (U.S. EPA). EPA Air Pollution Control Cost Manual , 6 th ed. U.S. EPA Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. 2002. Section 1, Chapter 2 – Cost Estimation: Concepts and Methodology.

17 Tsu, Wilson. Barrick Goldstrike Mines, Inc. [Communication with E. Steen, Air Sciences Inc. (pump horsepower)]. November 2, 2007.

18 Valdez, Ron. Barrick Goldstrike Mines, Inc. [Communication with E. Steen, Air Sciences Inc. (pump horsepower)]. November 5, 2007.Appendix 3, Page 38 

# Appendix A

GENERAL ARRANGEMENTAppendix 3, Page 48 

# Appendix B

PIPING AND INSTRUMENTATION
DIAGRAMSAppendix 3, Page 65 

# Appendix C

PROCESS FLOW DIAGRAMSAppendix 3, Page 69 

# Appendix D

PROCESS DESIGN CRITERIA

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 1 of 16 Rev: Date: Status: Prepared By: Checked By: Approved By:

B 1-Jun-10 Issued for Permit Y. Weng A. McIntosh J. Wright A 1-Jun-10 Issued for Permit Y. Weng A. McIntosh J. Wright



### 1. Purpose The purpose of this document is to record the process requirements for the project and present a summary of the process design criteria used for the alkaline autoclave mercury controls.

2. POX Offgas Treatment Plant

2.1. System Overview Known principles of gas cleaning and mercury removal have been used in the system design.

These include:

 Intimate contact between liquid / gas streams at a controlled pressure drop

 Multiple contact points through stages of liquid spray

 Several steps of impurity removal and gas conditioning in series

 Process gas residence time to promote condensation and particle / droplet growth

 Cooling of process gas to known levels where elemental mercury will condense

 Application of proven carbon bed adsorption technology for mercury removal to meet required emission limits

The system can be broken into wet and dry areas. In the wet area the process gas is conditioned to remove water vapour and further cooled to promote elemental mercury condensation. Removal of mercury particulate and fume will be achieved using the mechanisms of gas / liquid contact and residence time. Conditioning of the process gas is required for the downstream carbon bed. A key intent of the system design is to shift mercury capture away from the carbon bed system by removing the maximum amount of mercury from the gas stream before the carbon bed. The carbon bed has the ability to handle excursions in mercury inlet loading but at the expense of reduced life and more frequent change-outs.

Of particular importance to the system design is the mercury speciation that is projected for the system. A very high proportion (94%) of the mercury as elemental was determined during the trial 1 

### . The wet gas condenser and carbon bed are critical to the system operation. Special care has been taken with the carbon bed design to ensure effective gas distribution and mercury removal.

2.2. Background of Aker Chemetics / Application of Experience Aker Chemetics is a technology based engineer ing design company. The technologies are offered on a worldwide basis to customers in the form of engineered systems, proprietary and non-proprietary equipment, as well as fully erected systems and plants.

Aker Chemetics technical expertise is divided into two areas. The Acid Technology Group offers technology for the cooling, recovery, re-concentration and production of sulphuric

1 An alkaline plant trial was completed in March 2010, per approval from NDEP under NAC 445B.232.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 2 of 16 

### acid to the chemicals, fertiliser and non-ferrous smelting industries. The Chemical Technology Group offers technology for the pr oduction of sodium chlorate, chlorine and caustic soda, chlorine dioxide, hydrochloric acid, and calcium hypochlorite to the chemical and pulp industries.

In a non-ferrous (Copper, Lead, Zinc, etc.) smelting system a roaster, converter, or furnace is typically used to process concentrate to a metal product. These pyro-metallurgical processes produce a gaseous vent stream at elevated temperatures and containing high levels of impurities in the form of dust (e.g.- metal oxides /sulphides), fumes (e.g.- Lead, Arsenic), and acid mist. The gas must be conditioned and impurities removed to low levels in a gas cleaning section to prevent contamination of the product acid or damage to downstream equipment.

These plants range in capacity from 80,000 to 180,000 SCFM (wet basis). A typical specification inlet to the Gas Cleaning section is provided in the attached table.

Item Inlet to Gas Cleaning System

Flow Rate, wet basis (ACFM) 120,000 to 400,000 Flow Rate, dry basis (DSCFM) 44,000 to 152,000 Temperature (F) 640 Pressure (psig) -0.05 Composition (volume %) SO 2 11.73 SO 3 0.04 O 2 10.61 N 2 61.30 CO 2 1.06 H 2 O 15.26 Impurities Total Particulate (grains / DSCF) 0.06 Arsenic Fume (grains / DSCF) 0.24 Lead Fume (grains / DSCF) 0.19



### The above conditions are both larger in volumetric capacity and magnitudes higher in impurity loading than that under consideration for the POX Offgas Treatment Plant.

Aker Chemetics has taken experience gained in past projects and equipment supply within metallurgical gas cleaning systems and applied it to the POX Offgas Treatment Plant. The Scrubber Venturi, Separator Vessel, Gas Cooling Tower, and Wet Gas Condenser have all been proven in operation for many years at other locations. Process Criteria used in their design have been applied to the POX Offgas Treatment Plant with adjustments made where appropriate.

2.3. Process DescriptionThe POX Offgas Treatment Plant (the Plant) treats the vent gas from the pressureoxidation autoclave circuits to reduce mercury emissions to the atmosphere. The Plant consists of the following major treatment stages:

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 3 of 16 

### 1) Scrubber Venturi/Separator System – quenches the process gas from 203°F to 120°F and removes the bulk of the particulate mercury and part of the oxidized mercury contaminants from the gas stream. 2) Gas Cooling Tower System – quenches the pr ocess gas, to provide further cooling and removes a portion of particulate and oxidized mercury contaminants. 3) Wet Gas Condenser System – further cools the process gas using an ammonia refrigerant and separates condensed elemental mercury from the gas stream. 4) Carbon Bed System – removes elemental and oxidized mercury via chemio-adsorption onto sulphur-impregnated activated carbon.

The vent gases requiring treatment are drawn to the Plant under the suction of a Booster Fan.

The autoclave vent gases, saturated with water at 203 o 

### F, enter the variable throat Scrubber Venturi, and are adiabatically quenched by the circulating cold condensate. The venturi effect removes not only the condensed water, but also a portion of the particulate and oxidized mercury contaminates from the process gas. From the Scrubber Venturi, the process gas proceeds to the Separator Vessel, which also draws in ambient vent gas from the Slurry Cooler Surge Tanks. The Separator Vessel is equipped with staged liquid sprays to further quench the gas and provides residence time for growth of droplets. The vessel diameter has been sized for a slow gas velocity that will allow separation of the majority of liquid droplets. The Separator Vessel is equipped with a chevron mist eliminator on the top to minimize carryover of liquid droplets.

The condensate liquid from the Separator Vessel bottom is circulated by the Scrubber pump and cooled in the plate and frame Scrubber Cooler. The cooled condensate is delivered to the Venturi Scrubber and the Separator Vessel sprays to cool the incoming gas stream. Excess liquid from the circuit is purged on level control to the Water Treatment System.

From the Separator Vessel, the process gas fl ows to the Gas Cooling Tower, where it is further quenched via counter-current contact with circulating cold condensate. The tower packing provides additional contact to remove particulate and oxidized mercury contaminants from the gas stream.

The condensate liquid exiting the Gas Cooling Tower bottom is cooled in the plate and frame Gas Cooling Tower Cooler and circulated to the tower trough distributor via the Gas Cooling Tower Pump. Excess liquid from the circuit is purged on level control to the Water Treatment System. The tower is equipped with a chevron mist eliminator on the top to minimize liquid carryover. The target gas stream temperature exiting the Gas Cooling Tower System is 77°F.

In the duct exiting the Gas Cooling Tower, an in-line Gas Cooling Tower Separator is provided to remove any condensed elemental mercury. Mercury condensation may begin at this stage during cold weather, when the condensate loop is running colder than the design temperature. The Separator consists of a dual-layer mist eliminator, a coalescing mesh pad followed by a chevron.

From the in-line Gas Cooling Tower Separator, the gas enters the Wet Gas Condenser, a counter-current shell-and-tube exchanger. The tube-side process gas is cooled by the

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 4 of 16 

### vaporization of liquid ammonia, supplied at 32°F to the shell. The target gas stream temperature exiting the Wet Gas Condenser is expected to be as low as 39°F. At this temperature, elemental mercury is expected to be condensed out from the gas stream. Cold condensate is continuously sprayed onto the tubes to capture the condensed mercury and flows to the Condensate Tank. The Condensate pump circulates the spray liquor and purges the excess condensate from the circuit to the Water Treatment System.

From the Wet Gas Condenser, the process gas flows to the in-line Wet Gas Coalescer, a dual-layer mist eliminator. This separator offers additional agglomeration and separation of the condensed elemental mercury. The process gas then proceeds to the Wet Gas Separator Vessel, which provides several mechanisms to minimize carryover of water and condensed mercury droplets to the Carbon Bed System. The tangential inlet on the Wet Gas Separator Vessel creates a swirling effect on the gas. Two horizontal perforated baffles provide additional tortuous path and impingement as the gas flows upward through the vessel. Fine mist carryover is minimized via a mesh pad in the vessel top section.

Excess condensate from the Wet Gas Separator Vessel, as well as the inline separators, is collected in the Condensate Tank.

Prior to entering the Carbon Filter, the process gas is conditioned to 70% relative humidity to prevent moisture condensation in the Filter. Condensation, which creates a liquid barrier on the activated carbon, hinders the adsorption kinetics and therefore the performance of the Filter. Humidity control is achieved by introducing heated ambient air to the saturated process gas exiting the Wet Gas Separator. Direct heating of the process gas is not recommended as the process gas is rich in oxygen.

The conditioned process gas enters the Carbon Filter horizontally and passes through two trains of carbon absorbers. Each train consists of a primary followed by a secondary bed. Mercury contaminants in the gas stream are captured by the sulphur on the activated carbon to form mercury sulphide. The configuration of 2-bed in series minimize spent carbon. A mercury breakthrough in the primary bed would trigger its replacement and extend the life of the secondary bed.

The treated gas exiting the Carbon Bed System is drawn by the Booster Fan to the Plant Stack.

Cooling water to the Plant is supplied in an evaporative cooling tower circuit.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 5 of 16 

### 2.4. Plant Capacity

The Plant is designed to receive the following vent gas streams

Item Vent from Scrubber #252-424-610 Autoclave 4 Circuit Vent from Scrubber #252-424-620 Autoclaves 5 & 6 Circuit Combined Vent from Slurry Cooler Surge Tanks #252-482-230A & 611
Flow Rate, wet basis (ACFM) 33,364 66,729 766 Flow Rate, dry basis (DSCFM) 2,448 4,895 556 Temperature (F) 203 203 77 Pressure (psig) 0 0 0 Composition (volume %) O 2 10.0 10.0 20.2 N 2 0.0 0.0 76.8 CO 2 2.0 2.0 - H 2 O 88.0 88.0 3.0

Mercury Total (grains/DSCF) 6.8 (10 -3 ) 6.8 (10 -3 ) 0 Particulate (wt %) 1 1 - Oxidized (wt %) 5 5 - Elemental (wt %) 94 94 -

Tie-Point Existing Stack Existing Stack Tank Vent



### Autoclave vent gas flows and compositions are derived from testing conducted in an alkaline feed trial. These are then adjusted for projected peak ore feed rates and autoclave operating conditions.

The Slurry Cooler Surge Tank vents are open to atmosphere and will be collected under vacuum at the inlet of the Separator Vessel. Vent flows have been estimated based on maximum inflow and outflow conditions to the tanks. Mercury content and speciation has not been tested but is expected to be negligible in comparison to the autoclave conditions. A gooseneck at the tank vent allows ambient ai r to be drawn to the POX Offgas Treatment System thereby preventing excess vacuum at the tanks. The vent flow for design purposes has been assumed to be air as this adds the maximum quantity of inert gas to the plant.

Turndown Capability The Plant is designed to handle turndown operation where only 1 Autoclave circuit is running.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 6 of 16 

### 2.5. Design Basis

Stack Gas Characteristics

Flow 13,500 ACFM 9,850 DSCFM Temperature 89 o 

### F Pressure Ambient psig Composition O 2 

### 66.7 vol % N 2 

### 19.9 vol % CO 2 

### 12.2 vol % H 2 

### O 1.2 vol % Mercury 7.8 (10 -5 

### ) grain/dscf

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 7 of 16 

### 2.6. Equipment Design Criteria

2.6.1. Scrubber Venturi / Separator Vessel System

Equipment Function

Scrubber Venturi - Quench feed gas via direct contact with circulating cold condensate - Separate particulates and fumes from gas stream through venturi effect - Variable throat to maintain pressure drop and particle removal efficiency at turndown

Separator Vessel - Quench process gas via direct contact with 3 stages of cold condensate spray - Promote separation of condensate via design residence time / limit to gas superficial velocity - Minimize droplet carryover via chevron mist eliminator

Scrubber Cooler - Cool circulating condensate prior to Scrubber Venturi and Separator Vessel sprays.

Scrubber Pump - Provide cold condensate to the Scrubber Venturi and Separator Vessel to maintain minimum liquid to gas ratios - Provide sufficient head to ensure spray performance. - Transfer excess condensate to water treatment system

Design Parameters

PARAMETER UNIT DESIGN PROCESS PARAMETERS Scrubber Venturi Minimum Liquid to Gas Ratio usgpm /1000 acfm ( gas inlet) 7.5 Liquid Flow (FI-652506)

Pressure Drop in wc 20 Throat Pressure Drop (PDI-652001) Separator Vessel Residence Time Sec >5 Based on gas inlet conditions, inherent to separator vessel design Gas Superficial Velocity ft/sec <7.5 Based on gas inlet conditions, inherent to separator vessel design Minimum Liquid to Gas Ratio usgpm / 1000 acfm (gas inlet) 29 Liquid Flow (FI-652506)

Exit Gas Temperature o F 120 Gas Temperature (TI-652102)

Scrubber Cooler Condensate Exit Temperature o F 77 Liquid Temperature (TI-652502, TI-652505)



### Basis of Design Parameters

 Scrubber Venturi Minimum Liquid to Gas Ratio . The ratio selected is based on past experience and industry norms. Higher ratios lead to greater opening of variable

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 8 of 16 

### throat to maintain system pressure drop and can also lead to material erosion over time.

 Scrubber Venturi Pressure drop . Value selected is a balance between required fan capacity and desired impurity removal efficiency. For pressure drop shown the Aker Chemetics predictive models show remova l efficiencies of greater than 99% for particles of 1 micron and 97% for particles of 0.5 micron. There are diminishing returns for any higher pressure drop selection and with given mercury speciation.

 Separator Vessel Residence Time . Value selected is based on past experience and industry norms for condensation of arsenic fume from a process stream where a retention time of 3 seconds has been used. The retention time for the POX Offgas Treatment System has been increased to re flect requirement for gas cooling in addition to growth of particles / droplets. Retention time is based on separator inlet volumes which will reduce as process gas passes through the vessel. True retention time is higher than value shown.

 Separator Vessel Gas Superficial Velocity . Value selected is based on published information for liquid / gas separators. Value used in design is less than maximum allowable of 10ft/sec by calculation.

 Separator Vessel Minimum Liquid to Gas Ratio . The ratio selected is based on three equilibrium approaches from multi-stage contact of the process gas with liquid sprays. Resultant temperatures of liquid and gas are an outcome of this energy balance.

 Separator Vessel Exit Gas Temperature . The temperature selected is based on optimizing the split of expected elemental mercury free condensate.

 Scrubber Cooler Condensate Exit Temperature . The temperature selected is based on highest expected cooling water supply conditions of 68 o 

### F and an approach of 9 o 

### F at the heat exchanger. A tighter approach makes cooler selection uneconomic.

Estimated Mercury Removal The estimated mercury removal efficiency is based on correlation between venturi throat pressure drop and removal efficiency of particles of various sizes. Particle size distribution was not measured during the alkaline trials. A r eduction in efficiency from the predictive model was used as shown below due to uncertainty with size distribution and lower inlet loads than past experience. Exit gas temper ature exceeds level where condensation of elemental mercury is expected to occur.

Mercury Species % Removal efficiency


### Particulate 90 Oxidized 80 Elemental 0

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. U npublished. Unauthorised use or repr oduction prohibited. Page 9 of 16 

### 2.6.2. Gas Cooling Tower System

Equipment Function

Gas Cooling Tower - Cool process gas via direct contact in a packed section with circulating cold condensate - Capture particulates and fumes from gas str eam in packed section by liquid / gas contact - Provide constant heat load to downstream wet gas condenser / refrigeration skid - Condense elemental mercury when ambient conditions allow operation of circulated liquid at lower temperatures

Gas Cooling Tower Cooler - Cool circulating condensate prior to Gas cooling Tower.

Gas Cooling Tower Pump - Provide cold condensate and maintain minimum liquid to gas ratios - Provide sufficient head to ensure distributor performance. - Transfer excess condensate to water treatment system

Design Parameters

PARAMETER UNIT DESIGN PROCESS PARAMETERS Gas Cooling Tower Minimum Liquid to Gas Ratio lb liquid / lb process gas outlet >5 Liquid Flow (FI-654006)

Packed Height ft 16 Inherent to tower design Packing Loading % of load 75 Inherent to Gas Cooling Tower design and packing selection Exit Gas Temperature o F 77 Gas Temperature (TI-653003)

Gas Cooling Tower Cooler Condensate Exit Temperature o F 77 Liquid Temperature (TI-654003)



### Basis of Design Parameters

 Gas Cooling Tower Venturi Minimum Liquid to Gas Ratio . The ratio selected is based on past experience and industry norms for packed tower applications.

 Gas Cooling Tower Packed Height . Value selected is based on past experience and industry norms for metallurgical applications. Measured plant data at metallurgical sites has shown that this is sufficient packing for cooling to a tight temperature approach.

 Gas Cooling Tower % of loading . Value selected is based on past experience and industry norms. Loading is within recommended range provided by packing vendors.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 10 of 16 

###  Gas Cooling Tower Exit Gas Temperature . The temperature selected is the lowest that can be considered based on ambient conditions.

 Gas Cooling Tower Cooler Condensate Exit Temperature . The temperature selected is based on highest expected cooling water supply conditions of 68 o 

### F and an approach of 9 o 

### F at the heat exchanger. A tighter approach makes cooler selection uneconomic.

Estimated Mercury Removal A packed column is effective for impurity removal in the 1 to 2 micron range. It is expected that the retention time, gas / liquid contact, and cooling of the process gas will promote growth of condensed fume and particulate. Without definition of inlet particle distribution and actual system measurements an accurate calculation of estimated removal is not possible. A value of 50% removal for particulate and fume was therefore assumed. Exit gas temperature at design exceeds level where condensation of elemental mercury is expected to occur. Inlet to the gas cooling tower elemental mercury comprises approximately 99% of total remaining and assumptions made in terms of particulate and fume removal efficiency have a limited impact to over all system performance.

Mercury Species % Removal efficiency


### Particulate 50 Oxidized 50 Elemental 0

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 11 of 16 

### 2.6.3. Wet Gas Condenser System Equipment Function

Gas Cooling Tower Separator - Coalesce and remove condensed elemental mercury (potentially in cold weather condition) in the gas exiting the Gas Cooling Tower via inertial impaction.

Wet Gas Condenser - Cool the process gas indirectly via liquid ammonia to condense elemental mercury vapour - Capture the condensed mercury via circulating liquid spray

Wet Gas Coalescer and the Wet Gas Separator Vessel - Coalesce and remove fine mercury droplets via inertial impaction. - Minimize water droplet carryover, via inertial impaction, to the Carbon Bed System

Condensate Tank - Collect drains from in-line Separators, Wet Gas Separator Vessel, and Wet Gas Condenser - Allow settling of condensed mercury - Provide hold-up volume for the overall Wet Gas Condenser System

Condensate Pump - Deliver cold condensate to the Wet Gas Condenser spray - Transfer excessive condensate to water treatment - Deliver washing fluid to mist eliminators intermittently

Design Parameters

PARAMETER UNIT DESIGN PROCESS PARAMETERS Wet Gas Condenser Process Gas Outlet Temperature F As low as 39 Gas Temperature T-655002

Liquid Spray Flow usgpm 44 Liquid Flow F-655204 Gas Cooling Tower Separator and Wet Gas Coalescer Mist Eliminator Type Mesh pad + Chevron Wet Gas Separator Vessel Superficial Gas Velocity ft/s 8.5 Based on gas inlet conditions, inherent to vessel design Inlet Gas Velocity ft/s 175 Bas ed on gas inlet conditions, inherent to vessel design



### Basis of Design Parameters

 Wet Gas Condenser Gas Outlet temperature . temperature selected prevents freezing on the heat exchanger tubes

 Liquid Spray Flow to Wet Gas Condenser. value selected is based on tube wetting rates from past experience and industry norm for wet gas condenser applications. The liquid spray serves to capture the condensed mercury. Due to its high surface

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 12 of 16 

### tension, condensed mercury tends not to precipitate out of the gas stream on its

own.

 Mist Eliminator Selection for Gas Cooling Tower Separator and Wet Gas Coalescer. selected dual layer (mesh pad followed by chevron vane) takes advantage of the high removal efficiency of mesh pad and the high gas velocity of chevron vane. High gas velocity through the mesh pad improves its capture of fine mist droplets. Most of the liquid captured in the mesh is re-entrained as larger droplets, which are then removed by the second layer of chevron vane.

 Wet Gas Separator Superficial Gas Velocity. velocity is calculated based on published information for liquid / gas separators and represents the terminal velocity of the entrained liquid particle. This velocity is the basis for sizing the diameter of the Separator Vessel.

 Wet Gas Separator Inlet Gas Velocity - value is within typical cyclone separator design range.

Expected Mercury Removal The Wet Gas Condenser System removes elemental mercury by cooling the gas below its mercury saturation temperature. The expected elemental mercury content in the gas exiting this system is determined based on mercury vapour pressure curve as shown.


### Figure 1: Saturated Mercury Vapor over Pure Mercury

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

30 40 50 60 70 80 90 Temperature (F)Hg Vapor Pressure(ppmv, based on 1 atm barometric)

(source: NIST Chemistry Web Book and Perry’s Chemical Engineering Handbook)



### As the proposed process is over an aqueous m edium, the elemental mercury in the gas exiting the Wet Gas Condenser is expected to be lower than the saturation concentration derived from the curve over pure mercury. A conservative assumption to use the saturation concentration over pure mercury was taken to ca lculate the removal efficiency of this stage and to design the downstream Carbon Filter.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 13 of 16 

### The expected elemental mercury removal efficiency is the difference between the mercury content at 39F and that in the feed gas to the Plant.

The various separation mechanisms in the Wet Condenser System are expected to remove a portion of the particulate and oxidized mercury. The removal efficiency is assumed to be 50% for each form and has minimal impact on the overall system performance given the dominant content of the elemental form.

Mercury Species % Removal efficiency


### Particulate 50 Oxidized 50 Elemental Up to 80

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 14 of 16 

### 2.6.4. Carbon Bed System

Equipment Function

Humidity Control Package (Inlet Screen, Heater, Mixer) - Condition process gas to 70% relative humidity prior to Carbon Filter by introducing warm ambient air to the oxygen rich process gas. - Prevent water vapour condensation which hinders mercury adsorption kinetics.

Carbon Filter - Adsorb mercury from the gas via chemical reaction with the sulphur-impregnated activated carbon. - Reduce overall spent carbon through a staged bed configuration. The primary bed is to be replaced at a higher frequency to extend the life of the secondary bed.

Design Parameters PARAMETER UNIT DESIGN PROCESS PARAMETERS Carbon Bed Inlet Gas Humidity % RH 70 Humidity Analyzer (A-662001) Inlet Mercury Load grain/dscf 1.3 - 6.0 (10 -3 ) Manual Sampling & Testing Primary Bed Residence Time sec 1.2 Based on gas inlet condition, inherent to bed design Fresh Carbon lb 12,000 Hg Adsorption Capacity % min. 15 Manual Sampling & Testing

Expected Replacement Years >1 Secondary Bed Residence Time sec 2.9 Based on gas inlet condition, inherent to bed design Fresh Carbon lb 28,800 Hg Adsorption Capacity % min 15 Manual Sampling & Testing

Expected Replacement Years >5 Outlet Mercury Load grain/dscf 7.8 (10 -5 ) Stack Testing



### Basis of Design Parameters

 Inlet Gas Humidity. value stated is specified by the carbon supplier

 Inlet Mercury Load . value selected is based on the expected mercury removal efficiencies in the upstream equipment

 Outlet Mercury Load . value selected is the allowable emission

 Bed Residence Time . value stated is specified by the carbon supplier to meet the outlet mercury load. The primary bed residence time is sufficient to concentrate mercury loading within the primary bed, thus allowing the secondary bed to function largely as a guard bed.

 Hg Adsorption Capacity. value stated is inherent to the property of the activated carbon and is provided by the carbon supplier

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 15 of 16 

###  Fresh Carbon and Expected Replacement . values states are based on the design residence time and the properties of the activated carbon.

Expected Mercury Removal The sulphur impregnated carbon has high affinity for elemental mercury and some affinity for the oxidized form. The bed packing is expected to remove a portion of the particulate mercury as well. The mercury removal efficiency is provided by the carbon filter supplier.

Mercury Species % Removal efficiency


### Particulate 50 Oxidized 25 Elemental ≥ 95

2.6.5. Booster Fan & Stack

Equipment Function

The Booster Fan moves the process gas through the Plant and releases it to atmosphere. The Stack allows for safe discharge to the atmosphere.

Design Parameters

PARAMETER UNIT DESIGN PROCESS PARAMETERS Booster Fan Pressure Drop in WC 77 Pressure (P-662041 & P-663070) Stack Stack Height ft 100 Tip Velocity ft/s ≥ 60 Based on inlet gas condition, inherent to design



### Basis of Design Parameters

 Booster Fan Pressure Drop . Value selected is based on plant pressure profile, accounting for the design pressure drop of equipment and ducting. An allowance for system pressure drop increase over time has been made in the fan selection.

 Stack Height - value selected matches the elevation of the existing autoclave scrubber stack tip. The release point is above other structures and equipment in the vicinity.

 Stack Tip Velocity – value selected provides adequate gas dispersion, typical of stack design.

### Barrick Gold Corporation POX Offgas Treatment Goldstrike, Nevada Aker Chemetics
A division of Aker Solutions Canada Inc. 

### Client Document Number Procedure

Process Design Criteria

10L18680-1-PRC-0001-RB

© Aker Chemetics, a division of Aker Solutions Canada Inc. Unpublished. Unauthorised use or re production prohibited. Page 16 of 16 

### 2.6.6. Cooling Tower

Equipment Function Water is circulated from a dedicated evaporative cooling tower to the Scrubber Cooler, Gas Cooling Tower Cooler, and refrigeration skid. At design conditions the energy transferred into the water system is estimated at 195 MMBtu/h.

Design Parameters

PARAMETER UNIT DESIGN PROCESS PARAMETERS Cooling Tower Maximum Wet bulb Temperature o F 59 Inherent to site ambient conditions

Cooling Water Supply Temperature o F 68 Liquid Temperature (TI-918305)



### Basis of Design Parameters

 Maximum wet bulb temperature. value selected is based on evaluation of psychometric data on an hourly basis at the site for the calendar years 2007, 2008, and 2009. This value is consistent with existing evaporative cooling towers at site and previous studies.

 Cooling Water Supply temperature. value selected is based on past experience and industry norms. The value has been confirmed though cooling tower vendor quotations.

2.7. Control Philosophy The Plant will be controlled via existing Autoclave DCS system and operations staff. Alarms, Interlocks, data acquisition, trending, and control will be incorporated into the plant design.

Full installed spares will be provided for equipment critical to plant operation.

Emergency Power is to be provided to the Booster Fan.Appendix 4, Page 1 

# Appendix 4

Request for de minimis Emissions Determination

Thermal Mercury Emitting UnitAppendix 5, Page 1 

# Appendix 5

APPLICATION CERTIFICATION

The responsible official must sign and date th e application certification found in Appendix 5. If the application is signed by a person other than the responsible official, as defined in NAC 445B.156, the application will be returned as incomplete.

Note: According to NAC 445B.156, Responsible Official means: 1. For a corporation: (a) A president; (b) A vice president in charge of a principal business function; (c) A secretary; (d) A treasurer; or (e) An authorized representative of such a pe rson who is responsible fo r the overall operation of the facility and who is designated in writing by the officer of the corporation and approved in advance by the director. 2. For a partnership or sole proprietorship: a general partner or the proprietor, respectively. 3. For a municipality or a state, federal or other pub lic agency: a ranking elected official or a principal executive officer, including, for a federal agency, a chief executive officer who has responsibility for the overall operations of a principal geographic unit of the agency. 4. For an affected source: the designated representa tive or his alternate, as defined in 42 U.S. C. § 7651 a (26).Appendix 5, Page 2 

### PLEASE NOTE THE FOLLOWI NG REQUIREMENTS WHICH APPLY TO PERMIT APPLICANTS DURING THE APPLICATION PROCESS:
A. A permit applicant must submit supplemen tary facts or corrected information upon discovery [NAC 445B.297.1(b)].
B. A permit applicant is required to provide any additional information which the Director requests in writing within the time specifi ed in the Director's request [NAC 445B.297.1(c)].

C. Submission of fraudulent data or other information may result in prosecution for an alleged criminal offense (NRS 445B.470).
CERTIFICATION: I certify that, based on in formation and belief formed after reasonable inquiry, the statements contained in this application a re true, accurate and complete.

Signature of Responsible Official

Joseph Giraudo Environmental Manager Print or Type Name and Title

Date