DEVELOPMENT OF THE MACT FLOORS AND MACT FOR THE PROPOSED 

NESHAP FOR GOLD MINE ORE PROCESSING AND PRODUCTION 

Metals and Minerals Group 

Sector Policies and Programs Division 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 

April 14, 2010 
1 

Development of the MACT Floors and MACT for the Proposed NESHAP for Gold Mine 

Ore Processing and Production 

1. Selection of Affected Source 

The Gold Mine Ore Processing and Production source category consists of facilities 

engaged in processing gold ore to recover gold using roasters, autoclaves, carbon kilns, melt 

furnaces, retorts, electrowinning, and preg tanks. There were approximately 21 gold mine ore 

processing facilities operating these processes in the United States in 2008. 

 The proposed rule would apply to each new or existing affected source. We are 

proposing MACT standards for mercury emissions for three affected sources in the gold mine 

ore processing source category that reflect differences in process operations, the sources of 

mercury entering the processes, and the nature of the emissions. One affected source is ore 

pretreatment, which applies to five existing facilities (although one is not currently operating), 

and we have mercury emissions data for all of these facilities. The ore pretreatment affected 

source includes roasting operations and autoclaves that pretreat refractory ore, which contains 

organic carbon and sulfide mineral grains that prevent the initial use of cyanide leaching to 

effectively extract the gold from the ore. The refractory ore is oxidized in the roaster or 

autoclave, converting it to an “oxidized” ore, which can then be effectively leached with cyanide 

solution. Mercury enters these processes with the ore. The potential for mercury emissions from 

this affected source is directly related to the amount of ore processed in the autoclaves and 

roasters; consequently, the appropriate format for the proposed standard for this affected source 

is pounds of mercury emissions (lb) per ton of ore processed (lb/ton of ore). In 2007, the ore 

pretreatment sources accounted for approximately 67 percent of the mercury emissions from the 

source category. 

 The second proposed affected source is carbon processes, which includes those gold 

production operations that use carbon to collect (adsorb) the gold and mercury from solution and 

the process units that follow (i.e., carbon kilns, pregnant tanks, electrowinning cells, retorts and 

melt furnaces). Mercury emissions are subsequently generated by these process units. In 

developing a proposed format for the emission limit for carbon processes, we examined the use 

of loaded carbon, concentrate, and gold production in the denominator of a pound per ton format. 

In other NESHAP, we have typically used the amount of feed throughput or the amount of 
2 

product produced in the denominator of the emission limit. Although loaded carbon can be 

considered the “primary feed”, we discovered there were potential issues with its measurements 

(e.g., default values were used for density), we were unsure that the data from different facilities 

were comparable, and it was not a quantity that has been required to be reported under existing 

State regulatory programs. We rejected the use of gold produced because some facilities do not 

produce gold (they send the intermediate product to offsite refineries), some facilities produce 

more silver than gold, and the quantity of gold varies depending on the percent of gold in the 

product. The primary intermediate product that is common to all of the facilities with these 

carbon processes is the gold-bearing concentrate, which is the input to retorts or melt furnaces. 

Further, concentrate is closely related to the final product because it contains about 60 percent 

gold, and because of its value, it is carefully and accurately weighed and records of the quantities 

are kept. Concentrate is also required to be reported under the Nevada Division of 

Environmental Protection (NDEP) program, so we had comparable and reliable data from the 

different gold mine facilities. Consequently, we decided that the most appropriate format of the 

emission limit for the carbon processes is lb/ton of concentrate. 

There are approximately 14 facilities with the carbon processes, and we have mercury 

emissions data for 11 of these facilities. In 2007, the carbon process sources accounted for 

approximately 30 percent of the mercury emissions from the source category. 

 The third proposed affected source is non-carbon concentrate, which includes facilities 

with gold ore processes that do not use carbon or ore pre-treatment. These facilities do not have 

roasters, autoclaves, or carbon kilns and instead only use retorts and melt furnaces to recover the 

gold and liberate mercury from the concentrate. The amount of mercury entering these processes 

and potential mercury emissions are directly related to the amount of concentrate processed; 

consequently, the appropriate format for the proposed standard for this affected source is lb/ton 

of concentrate processed. There are about four gold mine ore processing facilities sources with 

non-carbon concentrate affected sources, and we have mercury emissions data for two of these 

facilities. In 2007, the non-carbon concentrate sources accounted for approximately 3 percent of 

the mercury emissions from the source category. 

2. Approach for Developing the MACT Floor 

Pursuant to Section 112(d) of the Clean Air Act, the maximum achievable control 

technology (MACT) standards for existing affected sources must be at least as stringent as the 
3 

average emissions limitation achieved by sources in the MACT pool, that is, the best 

performing 12 percent of existing affected sources for which the Administrator has data for 

source categories with 30 or more sources or the best performing 5 sources for source 

categories with fewer than 30 sources. This level of minimum stringency is called the MACT 

floor. For new sources, MACT standards must be at least as stringent as the control level 

achieved in practice by the best controlled similar affected source. 

 The MACT floor limits for each of the three affected sources were calculated based on 

the performance of the lowest emitting (best performing) sources in each of the MACT pool 

sources. We ranked all of the sources for which we had valid data representing current 

performance based on their emissions and identified the lowest emitting of the existing 

affected sources, which included four facilities with ore pretreatment processes, 11 facilities 

for those with carbon processes, and two facilities with the non-carbon concentrate processes. 

For new source MACT, the floor was based on the best performing source in each of the three 

affected sources. 

 The run-by-run data and the details of the statistical calculations are provided in 

Appendices A through E. 

2.1 Statistical Approach for Existing Sources 

To calculate the MACT floor limit for each of the affected sources, we established and 

ranked sources’ emissions from lowest to highest. The data on which the limits are based are 

expressed in terms of pounds of mercury emitted per ton of input, where the gold mine ore is the 

input for the ore pretreatment processes and concentrate is the input for the carbon processes and 

the non-carbon concentrate processes. 

The emissions data for those best performing affected sources were used to determine the 

emission limits to be proposed, with an accounting for variability. EPA must exercise its 

judgment, based on an evaluation of the relevant factors and available data, to determine the 

level of emissions control that has been achieved by the best performing sources under variable 

conditions. The Court has recognized that EPA may consider variability in estimating the degree 

of emission reduction achieved by best-performing sources and in setting MACT floors. See 

Mossville Envt’l Action Now v. EPA, 370 F.3d 1232, 1241–42 (D.C. Cir 2004) (holding EPA 

may consider emission variability in estimating performance achieved by best-performing 
4 

sources and may set the floor at a level that a best-performing source can expect to meet “every 

day and under all operating conditions”). 

 To calculate the achieved emission limit, including variability, we used the equation:

T df T UPL = x + t v

where: 

T x = the average total emission rate over the best performing affected sources, 

df t = the 99th percentile of the t distribution, and 

T v = the total variance for the top performing affected sources. 

The degrees of freedom associated with df t is given by: 

∑ ∑ ( ) = = = − N

i

M

j ij

i

df n

1 1

1 

where: 

N = number of best performing affected sources (2 to 5 for the three affected sources), 

Mi = number of mercury emitting processes at each affected source, and 

nij = number of mercury emission test runs for each process unit. 

The average total emission rate ( T x ) is calculated from: 

∑=

=

N

i

T Ti x

N

x

1

1

where: 

N = the number of top N affected sources (N = 2 to 5), 

Ti x = the total emission rate of an entire ith affected source. 

To calculate Ti x : 

∑=

=

Mi

j

Ti ij x x

1

where: 

Mi = the number of distinct units within the ith affected source (i.e., we count all the distinct 

units in an affected source, so if a process type has two or more units, then each of those 

units must be counted), 

ij x = the unit average for the jth unit within the ith affected source. 
5 

To calculate ij x :

∑=

=

nij

k

ijk

ij

ij x

n

x

1

1

where: 

nij = the number of runs within the jth unit of the ith affected source, 

xijk = the observation associated with the kth run within the jth unit and ith affected source. 

The total variance ( T v ) consists of the following two variance components: 

T B W v = v + v

The first variance component ( B v ) is simply the variance of T x (the average total emission rate 

over all affected sources). Suppose 2 var( ) ij ijk s x = is the variance of an individual run in the jth 

unit and ith affected source, then the variance of the unit average, ij x in the jth unit and ith 

affected source is 

ij

ij

ij n

s

x

2

var( ) = . 

If all units operate independently, then the unit variances, 2

ij s , will be additive. Therefore, based 

on the assumption of variance additivity, the variance of the total emission rate of the ith affected 

source is 

∑=

=

Mi

j ij

ij

Ti

n

s

x

1

2

var( , )

and the variance of the average total emission rate over all affected sources is 

 

∑∑= =

= =

N

i

M

j ij

ij

B T

i

n

s

N

v x

1 1

2

2

1 var( . )

The second variance component ( Wv ) is the variance of T new x , , the total emission rate 

from new test runs at an affected source in the future to determine compliance. The theoretical 

formulation of Wv based on these future runs is: 
6 

,, , 2

1 11

1 var( ) var( ) var( )

M Mm

W T new j new jk new

j jk

vx x x = == m == = ∑ ∑∑ , 

where jk new , x refers to the kth run of the jth unit in the new affected source, and M is the number 

of units in the new affected source. Also note that the number of units, M, in the affected source 

to be tested in the future is unknown and may vary. 

However, the theoretical formulation informs us how to derive an operational

formulation of Wv based on the data available from the runs already completed from the top N

affected sources: 

2

2

1 11 11

11 1 var( )

Nm N M M i i

W ijk ij

i jk i j

v xs

N m Nm = == ==

⎛ ⎞ = = ⎜ ⎟ ⎝ ⎠ ∑ ∑∑ ∑∑

 

 Substituting into the equation provided for UPL earlier and rearranging yields: 

2

1 1

1 11 N M i

T df ij

i j ij

UPL x t s

N Nn m = =

⎛ ⎞

=+ + ⎜ ⎟

⎝ ⎠ ∑ ∑

The first term of the equation refers to the average total emission rate of the top N affected 

sources. The second term accounts for the expected variability in future measurements due to 

variations resulting from system operation and measurement activities, and this variability 

consists of two components. The first component accounts for the variability of the average 

total emissions of the existing lowest emitting MACT pool sources, and the second component 

accounts for the variability of the average of m new test runs based on the observed variance of 

individual runs within test conditions from the lowest emitting MACT pool sources (the 

second component typically accounts for the major portion of the overall variability). The 

variability factor assumes that variability from the individual best performing sources are 

independent, and thus are additive. This is a reasonable assumption because each individual 

best performing source has certain characteristics, such as material inputs, design and 

operation, etc. that are unique to that process unit. 
7 

2.2 Statistical Approach for New Sources 

 MACT for new sources is based on the UPL for the best performing source for each of 

the three types of affected sources and is calculated from: 

1 df T1 UPL = x + t v

where: 

1 x = the average total emission rate of the best performing affected source, 

df t = the 99th percentile of the t distribution with (n – 1) degrees of freedom, and 

T1 v = the total variance of the best performing source. 

The total variance of the best performing source is calculated from the formulas given in Section 

2.1, except that in this case, N = 1 and the subscript i is replaced by the subscript 1: 

1

2

1 1

1 1

1 1 M

T j

j j

v s = n m

⎛ ⎞

= + ⎜ ⎟

⎝ ⎠ ∑ , 

where 2

1 j s and 1 j n are the variance and number of runs, respectively, from the jth mercuryemitting unit of the best performing source, M1 is the number of distinct mercury-emitting units 

in this source, and m is the number of future runs to determine compliance (typically 3). 

3. MACT Floor for Mercury 

 Most of the mercury emissions data were obtained from annual testing that was 

required by the Nevada Division of Environmental Protection (NDEP) for 2007 and 2008.1

 

However, we used data from 2006 for an autoclave that was not tested in 2007 and did not 

operate in 2008, we used data from 2009 to replace 2008 test data at one facility that was 

invalidated due to not following the procedures in the State’s testing protocol, and we used 

2010 test data for the facility that installed new mercury emission controls on its roasters and 

resumed operation in late 2009. The tests generally consist of three runs per test per process 

at each affected source. Most of the measurements were made using EPA Method 29; 

however, Method 101A and the Ontario Hydro method were used in a few cases. There were 

cases where 2007 results represent emissions before a control device was installed, and 2008 

test results represent emissions after a mercury emission control device had been installed. In 

those cases, we used only the 2008 (controlled) test results to determine the top performing 

 

1 A complete listing of the emission test data is provided in a spreadsheet in docket item “Mercury Emissions Test 

Data” in the rulemaking docket. 
8 

affected sources. Emissions in lb/hr were multiplied by the number of hours the process 

operated in 2007 and 2008 and then divided by the process input rate for the year (in tons) to 

express mercury emissions in lbs per ton of input material. 

 NDEP identified several mercury tests conducted in 2007 and 2008 that were 

invalidated because of a failure to follow the reference test method or the established testing 

protocol. As a result, none of the test data for Barrick Goldstrike’s roasters and autoclaves for 

2008 were used in the analysis. However, we have 2007 and 2009 data for Goldstrike’s 

autoclaves and roasters which we did use in the analyses. The 2007 and 2008 tests for the 

retorts at Goldstrike were also invalidated; however, test data for 2009 was available for the 

retorts and was used in the analysis for the carbon group. Other tests that were invalidated 

included the 2007 tests at Coeur Rochester and one of the October 2008 tests at Marigold. 

 The MACT floor results are summarized in Tables 1, 2, and 3 for the three affected 

sources described earlier: ore pretreatment, carbon, and non-carbon concentrate processes, 

respectively. Valid data were available for all five of the facilities with ore pretreatment 

processes, two facilities with non-carbon concentrate processes, and 11 facilities with carbon 

processes. 

Table 1. MACT Floor Results for Ore Pretreatment 

Affected Source Average performance (lb Hg/million tons ore) 

Goldstrike 62 

Lonetree 64 

Gold Quarry 69 

Jerritt Canyon Mine 90 

Twin Creeks Mine 211 

Summary of Statistical Analysis 

Statistic Existing (top 5) New 

Average (lb/MM tons) 99 62 

df 101 48 

t 2.36 2.41 

Vb 59 275 

Vw 964 1,460 

Vt 1,020 1,740 

99% UPL (lb/MM tons), MACT Floor 175 163 
9 

Table 2. MACT Floor Results for Carbon Processes 

Affected Source Average performance (lb Hg/ton concentrate) 

Round Mountain 0.06 

Marigold 0.60 

Goldstrike 1.5 

Denton-Rawhide 1.8 

Twin Creeks Mine 2.9 

Cortez 3.1 

Gold Quarry 3.7 

Ruby Hill 6.9 

Florida Canyon Mine 9.7 

Lone Tree Mine 21 

Bald Mountain 39 

Summary of Statistical Analysis 

Statistic Existing (top 5) New 

Average (lb/1,000 tons) 1.4 0.06 

Df 158 12 

t 2.35 2.68 

Vb 0.017 0.00045 

Vw 0.245 0.00049 

Vt 0.26 0.00094 

99% UPL (lb/ton), MACT Floor 2.6 0.14 

Table 3. MACT Floor Results for Non-Carbon Concentrate Processes 

Affected Source Average performance (lb Hg/ton concentrate) 

Coeur Rochester Mine 0.07 

Midas Operations 0.11 

Summary of Statistical Analysis 

Statistic Existing (top 2) New 

Average (lb/ton) 0.09 0.07 

df 22 7 

t 2.51 3.00 

Vb 0.00052 0.00076 

Vw 0.0034 0.00076 

Vt 0.0039 0.0015 

99% UPL (lb/ton), MACT Floor 0.25 0.20 

 For carbon processes, we also examined the feasibility of an alternative equivalent 

MACT determination for new sources to provide flexibility in determining compliance because 

of the wide variety of process combinations and variations in input material that may be present 
10 

at future new carbon process sources. A well-established and conventional metric for expressing 

the degree of emission control is the percent control of the target pollutant. As shown in Table 2, 

Round Mountain has the lowest emission rate and is therefore considered the “best controlled 

similar source” under section 112(d)(3) of the CAA. Test data were available for 2007 for 

Round Mountain when the processes were uncontrolled, for 2008 when the controls were newly 

installed, and from 2009 after over one year of operation. The test results in Table 4 show 

showed a 99.6 percent mercury emission reduction in 2008 when the new carbon adsorption 

system was first installed and 93.5 percent reduction in 2009. Based on these results, we are 

proposing an alternative MACT floor limit 97 percent reduction in mercury emissions for new 

carbon process sources. This alternative floor limit was calculated based on the average 

reduction achieved by the best performing source in 2008 and 2009. 

Table 4. Test Results for Carbon Processes at Round Mountain 

Year Mercury emissions (lb/hr) Percent control 

2007 (uncontrolled) 0.0255 0 

2008 (newly installed controls) 0.00010 99.6 

2009 (controls after 1+ years) 0.00165 93.5 

Average -- 97 

4. Beyond the Floor2

 To evaluate opportunities for emission reductions beyond those provided by the 

MACT floor, we typically identify control techniques that have the ability to achieve an 

emissions limit more stringent than the MACT floor. Facilities with ore pretreatment 

processes have installed calomel scrubbers and venturi scrubbers on their roasters and 

autoclaves, respectively, to achieve the MACT floor for ore pretreatment processes. To 

achieve further reductions in mercury beyond what can be achieved using calomel scrubbers 

and venturi scrubbers, we identified as a beyond-the-floor option the installation of both a 

refrigeration unit and a carbon adsorber on autoclaves. This additional control system would 

follow the existing venturi scrubbers, and because the exhaust is saturated with water, a 

refrigeration unit or condenser would be required to remove water that would otherwise 

adversely affect the adsorptive capacity of the carbon adsorber. 

 We estimate the capital cost for the additional controls on the autoclaves as $890,000 

 

2 Additional details and documentation for the estimates of emissions, emission reductions, and costs are provided 

in the rulemaking docket (EPA-HQ-OAR-2010-0239). 
11 

with a total annualized cost of $720,000/yr. Mercury emissions would be reduced by 543 lbs, 

resulting in an estimated cost effectiveness of $1,300/lb. Energy consumption would increase 

by about 730 megawatt-hours per year, primarily due to the refrigeration unit. Solid waste 

generation and disposal (spent carbon loaded with mercury) would increase by about 3 tons 

per year. With this additional control, facilities with ore pretreatment processes could achieve 

an average performance of 90 lb/million tons of ore or less. Applying the UPL formula 

discussed earlier to account for variability, the 99th percentile UPL would be 149 lb/million 

tons of ore (see Table 5). 

Table 5. Beyond the Floor Results for Ore Pretreatment 

Affected Source 

Average performance 

(lb Hg/million tons ore) 

Goldstrike 62 

Twin Creeks Mine (70% reduction) 63 

Lonetree 64 

Gold Quarry 69 

Jerritt Canyon Mine 90 

Summary of Statistical Analysis 

Statistic 

Average achieved by all (lb/MM tons) 90 

df 101 

t 2.36 

Vb 42.5 

Vw 585 

Vt 628 

Affected Source 99% UPL (lb/MM tons) 149 

 For the carbon processes, we estimate that 9 of the 11 facilities for which we have data 

will need to improve control to meet the floor limits because these 9 plants have an average 

emission control performance that is above the MACT floor average performance. There are 

a few facilities in the middle of the rankings that will probably only need marginal 

improvements, but several facilities (especially those at the bottom of the ranking that average 

several times the floor average) will need significant improvements in mercury emission 

control. We estimate that the MACT floor limit for the carbon processes will reduce 

emissions by about 1,100 lbs per year, a reduction of 89 percent from current levels. Our 

estimates of impacts for the MACT floor indicate that almost all of the carbon processes 

currently have or soon will have carbon adsorbers installed to effectively control mercury 
12 

emissions (e.g., as a result of this proposed MACT standard or in response to the NDEP 

program). A beyond-the-floor analysis for this case is quite difficult because all of the 

processes are or will be equipped with efficient mercury emission controls, and it is quite 

difficult to identify a technology that might be applied to get additional controls, especially 

considering the very low mercury concentrations after control and the difficulty in obtaining 

efficient additional percent reductions for low concentration streams. For a beyond-the-floor 

analysis, we assumed that theoretically a second carbon adsorption system could be installed 

in series with the first one and would get an additional reduction of 90 percent. (We 

acknowledge that there is a great deal of uncertainty as to the additional percent reduction the 

redundant control system might achieve.) The capital cost was estimated as $3.2 million with 

a total annualized cost of about $1.2 million/yr. The emission reduction would be only 12 lbs 

per year. 

 For the non-carbon concentrate processes, we estimate that the MACT floor limit will 

result in an emission reduction for Midas Operations, which has an average performance 

above the floor average. We concluded that emissions at this facility would be reduced by 

adding a carbon adsorber to their melt furnace to achieve the floor level of control. For 

beyond the floor, we again assumed that the existing carbon adsorbers would be 

supplemented by adding a second control system of carbon adsorbers in series for all of the 

melt furnaces at both plants. We estimated the capital cost for the second set of control 

systems as $0.7 million and a total annualized cost of $306,000/year. Emissions would be 

reduced by 7 lb/year. 
13 

Appendix A. Mercury Emissions Data for the Ore Pretreatment Affected Source (lb/ton of 

Facility Unit Code 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs 

per unit 

DF (n-1) 

per unit 

Variance of unit average 

Facvari

Gold Quarry Calcine quench 1.4E-05 9.6E-06 1.4E-05 Gold Quarry Calcine quench 1.1E-05 1.3E-05 1.7E-05 1.3E-05 6.7E-12 6 5 1.1E-12 Gold Quarry Roaster Ore Preheater 1.3E-05 5.4E-06 4.5E-06 Gold Quarry Roaster Ore Preheater 2.6E-05 2.5E-05 1.5E-04 3.8E-05 3.3E-09 6 5 5.5E-10 Gold Quarry Roaster 9.0E-07 7.0E-07 7.9E-07 Gold Quarry Roaster 1.3E-06 1.6E-06 6.2E-07 9.8E-07 1.5E-13 6 5 2.4E-14 Gold Quarry Roaster Ore Grinder 1.7E-06 2.1E-06 1.5E-06 Gold Quarry Roaster Ore Grinder 1.5E-06 4.8E-06 1.8E-06 2.2E-06 1.7E-12 6 5 2.8E-13 Gold Quarry Calcine quench 1.7E-05 1.4E-05 9.5E-06 Gold Quarry Calcine quench 1.3E-05 1.5E-05 2.1E-05 1.5E-05 6.9E-05 1.5E-11 6 5 2.6E-12 5Goldstrike Roaster Ore Preheater 3.2E-07 5.0E-07 3.6E-07 Goldstrike Roaster Ore Preheater 2.6E-04 2.6E-05 1.4E-05 Goldstrike Roaster Ore Preheater 2.4E-05 5.1E-06 7.9E-07 Goldstrike Roaster Ore Preheater 8.6E-07 6.0E-07 5.2E-07 Goldstrike Roaster Ore Preheater 1.8E-06 1.4E-06 2.6E-07 Goldstrike Roaster Ore Preheater 2.2E-06 1.1E-06 2.6E-07 1.9E-05 3.8E-09 18 17 2.1E-10 Goldstrike Roaster Ore Preheater 8.7E-06 4.7E-06 1.7E-06 Goldstrike Roaster Ore Preheater 7.2E-06 5.2E-06 7.2E-06 Goldstrike Roaster Ore Preheater 8.5E-07 8.5E-07 3.9E-07 Goldstrike Roaster Ore Preheater 1.6E-06 8.5E-07 3.9E-07 3.3E-06 9.6E-12 12 11 8.0E-13 Goldstrike Roaster 7.2E-05 5.7E-05 5.3E-05 Goldstrike Roaster 1.3E-05 1.3E-05 1.7E-05 Goldstrike Roaster 2.0E-05 1.7E-05 1.3E-05 3.0E-05 5.5E-10 9 8 6.1E-11 Goldstrike Calcine quench 4.3E-06 3.0E-06 2.9E-06 3.4E-06 6.9E-13 3 2 2.3E-13 Goldstrike Calcine quench 3.5E-06 3.8E-06 3.3E-06 3.5E-06 4.7E-14 3 2 1.6E-14 Goldstrike Autoclave 2.6E-07 4.0E-07 4.7E-07 3.8E-07 1.2E-14 3 2 3.9E-15 Goldstrike Autoclave 6.6E-07 7.7E-07 5.5E-07 6.6E-07 1.2E-14 3 2 4.1E-15 Goldstrike Autoclave 1.4E-06 1.6E-07 1.8E-07 5.9E-07 5.2E-13 3 2 1.7E-13 Goldstrike Autoclave 1.4E-06 8.3E-07 4.6E-07 9.0E-07 6.2E-05 2.3E-13 3 2 7.7E-14 2Lone Tree Autoclave 8.9E-05 5.0E-05 5.3E-05 6.4E-05 6.4E-05 4.6E-10 3 2 1.5E-10 1Twin Creeks Autoclave 5.5E-05 1.4E-04 1.0E-04 Twin Creeks Autoclave 7.8E-05 2.6E-04 2.9E-05 Twin Creeks Autoclave 2.4E-04 1.2E-04 1.1E-04 Twin Creeks Autoclave 2.1E-04 1.3E-04 1.1E-04 Twin Creeks Autoclave 1.0E-04 2.0E-04 2.7E-04 1.4E-04 5.5E-09 15 14 3.6E-10 Twin Creeks Autoclave 1.1E-04 5.5E-05 5.3E-05 Twin Creeks Autoclave 8.7E-05 5.0E-05 3.5E-05 Twin Creeks Autoclave 4.9E-05 9.1E-05 8.0E-05 6.8E-05 2.1E-04 6.7E-10 9 8 7.4E-11 4Jerritt Canyon Ore dryer 1.4E-05 2.9E-05 1.9E-05 2.0E-05 Jerritt Canyon Roaster 3.4E-05 3.4E-05 4.0E-05 3.6E-05 9.5E-12 3 2 3.2E-12 Jerritt Canyon Roaster 4.2E-05 3.6E-05 2.2E-05 3.3E-05 9.0E-05 1.1E-10 3 2 3.7E-11 4

Average top 5: 9.9E-05 t DF: 101 Vb: 5

t(.99): 2.36 
14 

Appendix B. Mercury Emissions Data for the Carbon Processes Affected Source (lb/ton conce

Facility Unit 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs DF 

Variaof unavera

Marigold Refine circuit 3.7E-01 5.4E-01 4.3E-01 4.5E-01 7.9E-03 3 2 2.6EMarigold Refine circuit 7.7E-02 1.1E-01 9.1E-02 9.4E-02 3.5E-04 3 2 1.2EMarigold Refine circuit 8.5E-02 4.1E-02 2.5E-02 5.0E-02 9.5E-04 3 2 3.2EMarigold Carbon Kiln 7.5E-03 6.3E-03 7.0E-03 6.9E-03 6.0E-01 3.8E-07 3 2 1.3EDenton-Rawhide Carbon Kiln 3.2E-03 3.5E-03 1.7E-02 Denton-Rawhide Carbon Kiln 1.2E-02 6.5E-03 2.1E-03 7.2E-03 3.3E-05 6 5 5.5EDenton-Rawhide Electrowinning 6.5E-04 2.4E-04 6.4E-03 Denton-Rawhide Electrowinning 1.4E-02 2.6E-03 3.2E-03 4.5E-03 2.6E-05 6 5 4.4EDenton-Rawhide Refinery Furnace 8.9E-01 1.8E+00 1.5E+00 Denton-Rawhide Refinery Furnace 3.6E+00 1.6E+00 1.2E+00 1.8E+00 9.5E-01 6 5 1.6EDenton-Rawhide Retort 5.8E-05 6.3E-05 7.2E-05 Denton-Rawhide Retort 4.6E-05 1.5E-05 1.4E-05 4.5E-05 1.8E+00 6.2E-10 6 5 1.0EGoldstrike Carbon Kiln #2-Drum 5.4E+00 9.7E-01 5.6E-01 Goldstrike Carbon Kiln #2-Drum 4.3E-01 6.2E-01 4.2E-01 Goldstrike Carbon Kiln #2-Drum 1.4E+00 1.5E+00 1.3E+00 Goldstrike Carbon Kiln #2-Drum 1.3E+00 1.3E+00 1.6E+00 Goldstrike Carbon Kiln #2-Drum 1.4E+00 1.5E+00 1.3E+00 Goldstrike Carbon Kiln #2-Drum 6.4E-01 9.1E-01 4.0E-01 Goldstrike Carbon Kiln #2-Drum 2.4E-02 3.2E-02 3.8E-02 1.1E+00 1.3E+00 21 20 6.0EGoldstrike Electrowinning Cells 1.6E-01 1.8E-01 2.0E-01 Goldstrike Electrowinning Cells 2.7E-01 3.9E-01 2.2E-01 Goldstrike Electrowinning Cells 1.1E-01 7.1E-02 1.6E-01 2.0E-01 9.0E-03 9 8 1.0EGoldstrike Furnaces/EW Cells 2.9E-02 7.4E-02 2.3E-02 Goldstrike Furnaces/EW Cells 4.6E-02 1.3E-01 2.1E-01 8.5E-02 5.2E-03 6 5 8.7EGoldstrike Preg and Barren A Tanks 2.1E-02 1.4E-02 7.3E-03 Goldstrike Preg and Barren A Tanks 2.8E-03 3.2E-03 4.0E-03 8.7E-03 5.3E-05 6 5 8.8EGoldstrike Preg and Barren B Tanks 4.0E-03 1.3E-02 1.2E-02 Goldstrike Preg and Barren B Tanks 3.2E-03 2.0E-03 2.2E-03 6.1E-03 2.6E-05 6 5 4.4EGoldstrike Retort 1 5.9E-02 4.8E-02 3.3E-02 4.7E-02 1.7E-04 3 2 5.8EGoldstrike Retort 2 3.0E-02 1.5E-02 1.2E-02 1.9E-02 8.9E-05 3 2 3.0EGoldstrike Retort 3 5.8E-02 6.7E-02 6.3E-02 6.3E-02 1.8E-05 3 2 6.1ERound Mountain EW Cells 1.8E-02 7.9E-02 1.9E-02 3.9E-02 1.2E-03 3 2 4.1ERound Mountain Furnace 1.5E-04 1.8E-03 1.8E-03 Round Mountain Furnace 3.5E-02 9.6E-03 1.8E-02 1.1E-02 1.8E-04 6 5 3.0ERound Mountain Kiln and P/B Tanks 2.6E-03 2.9E-03 1.6E-03 Round Mountain Kiln and P/B Tanks 1.5E-02 1.0E-02 1.6E-02 8.0E-03 5.8E-02 4.3E-05 6 5 7.2ETwin Creeks Mine Electrowinning 2.3E-02 1.2E-01 4.9E-01 Twin Creeks Mine Electrowinning 1.7E+00 1.1E+00 1.2E+00 7.7E-01 4.5E-01 6 5 7.5ETwin Creeks Mine Furnace (New) 4.2E-01 1.2E-01 2.9E-01 Twin Creeks Mine Furnace (New) 4.8E-01 1.4E-01 3.9E-01 
15 

Facility Unit 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs DF 

Variaof unavera

Twin Creeks Mine Furnace (New) 6.6E-02 1.9E-02 4.8E-02 2.2E-01 3.2E-02 9 8 3.5ETwin Creeks Mine Furnace (Old) 1.0E+00 4.2E-01 6.5E-01 Twin Creeks Mine Furnace (Old) 2.2E+00 8.5E-01 9.3E-01 Twin Creeks Mine Furnace (Old) 2.2E-02 6.4E-02 9.3E-02 Twin Creeks Mine Furnace (Old) 7.8E-02 4.1E-02 2.7E-02 5.4E-01 4.3E-01 12 11 3.6ETwin Creeks Mine Juniper Carbon Kiln 2.2E-01 2.3E-02 9.6E-02 Twin Creeks Mine Juniper Carbon Kiln 2.8E-01 1.1E-01 9.1E-02 Twin Creeks Mine Juniper Carbon Kiln 7.5E-02 1.4E-01 1.4E-01 1.3E-01 6.1E-03 9 8 6.7ETwin Creeks Mine Preg/Barren Solution Tanks 2.1E+00 1.9E+00 3.6E-01 Twin Creeks Mine Preg/Barren Solution Tanks 8.2E-01 1.7E+00 7.8E-01 1.3E+00 5.3E-01 6 5 8.8ETwin Creeks Mine Retort A 8.1E-04 1.2E-03 2.4E-03 Twin Creeks Mine Retort A 4.2E-03 5.0E-03 1.0E-02 Twin Creeks Mine Retort A 2.6E-03 6.7E-04 1.1E-03 3.1E-03 9.6E-06 9 8 1.1ETwin Creeks Mine Retort B 3.5E-04 1.3E-03 1.4E-03 Twin Creeks Mine Retort B 1.6E-03 5.7E-03 2.8E-03 Twin Creeks Mine Retort B 5.1E-04 2.5E-03 5.1E-04 1.8E-03 2.8E-06 9 8 3.1ETwin Creeks Mine Retort C 7.6E-04 3.0E-03 5.4E-03 Twin Creeks Mine Retort C 7.5E-05 2.5E-04 3.1E-04 Twin Creeks Mine Retort C 4.7E-04 3.4E-03 4.1E-03 2.0E-03 4.0E-06 9 8 4.5ETwin Creeks Mine Retort D 2.2E-05 5.5E-03 2.1E-03 Twin Creeks Mine Retort D 6.5E-04 4.8E-04 1.7E-04 Twin Creeks Mine Retort D 1.2E-04 2.7E-04 5.0E-04 1.1E-03 2.9E+00 3.1E-06 9 8 3.5E

Average of top 5: 1.4E+00 t DF: 158 Vb: 

t(.99): 2.35 

Bald Mountain Barren Tank Stack 1.2E-02 4.7E-03 3.6E-03 6.7E-03 Bald Mountain Bullion Furnace 1.1E+00 9.7E-01 7.5E-01 Bald Mountain Bullion Furnace 1.4E+00 8.3E-01 1.0E+00 Bald Mountain Carbon Regeneration Kiln 7.3E-03 7.3E-03 1.1E-02 Bald Mountain Carbon Regeneration Kiln 3.6E-02 3.7E-02 7.1E-03 1.8E-02 Bald Mountain Electrowinning Cells 3.1E+00 5.3E+00 8.8E+00 Bald Mountain Electrowinning Cells 8.3E+01 6.9E+01 7.2E+01 Bald Mountain Electrowinning Cells 2.7E+01 3.1E+01 4.0E+01 3.8E+01 Bald Mountain Retort 1.4E-03 6.3E-03 3.0E-03 Bald Mountain Retort 2.8E-03 3.8E-03 3.2E-03 3.4E-03 3.9E+01 Cortez EW Cell #1 2.6E-02 1.9E-02 3.0E-02 2.5E-02 Cortez EW Cell #2 1.4E-02 3.5E-03 6.3E-03 8.0E-03 Cortez Induction Furnace #1 2.0E+00 1.9E+00 5.0E+00 3.0E+00 Cortez Kiln #1 1.3E-02 9.4E-03 3.7E-03 8.5E-03 Cortez Kiln #2 1.1E-03 6.4E-04 2.9E-03 1.6E-03 Cortez PB Tanks 1.0E-01 1.6E-01 8.8E-02 1.2E-01 3.1E+00 Florida Canyon Mine Carbon Kiln 1.0E+00 5.5E-01 6.7E-01 Florida Canyon Mine Carbon Kiln 1.3E+01 2.0E+01 2.0E+01 
16 

Facility Unit 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs DF 

Variaof unavera

Florida Canyon Mine Carbon Kiln 3.9E+00 4.2E+00 1.8E+01 9.1E+00 Florida Canyon Mine Dore Furnace 3.2E-01 8.3E-03 1.7E-02 Florida Canyon Mine Dore Furnace 1.5E-02 2.0E-02 5.1E-02 7.1E-02 Florida Canyon Mine Electrowinning Cell A 2.7E-01 1.4E-01 6.0E-01 Florida Canyon Mine Electrowinning Cell A 1.0E+00 1.5E-01 8.1E-01 5.0E-01 Florida Canyon Mine Electrowinning Cell B 1.0E-01 1.0E-01 7.1E-02 Florida Canyon Mine Electrowinning Cell B 7.6E-02 3.4E-02 4.6E-02 7.2E-02 Florida Canyon Mine Retort 1 3.1E-05 1.6E-05 1.3E-05 Florida Canyon Mine Retort 2 2.6E-03 1.2E-03 2.9E-04 Florida Canyon Mine Retorts 1& 2 2.7E-03 1.3E-03 3.0E-04 Florida Canyon Mine Retorts 1 & 2 6.9E-05 5.3E-05 6.2E-05 7.3E-04 9.7E+00 Lone Tree Mine Electrowinning East 1.4E+00 7.7E-01 1.2E+00 Lone Tree Mine Electrowinning East 7.0E-01 6.1E+00 7.8E-01 1.8E+00 Lone Tree Mine Electrowinning Scavenger 1.9E-01 7.1E+00 7.8E-02 Lone Tree Mine Electrowinning Scavenger 6.2E+00 2.5E-01 1.0E-01 2.3E+00 Lone Tree Mine Electrowinning West 2.7E+00 1.3E+00 5.0E-01 1.5E+00 Lone Tree Mine Pregnant & Barren Tanks 2.0E+00 3.3E+00 1.7E+01 Lone Tree Mine Pregnant & Barren Tanks 9.2E+00 2.1E+01 3.7E+01 1.5E+01 2.1E+01 Ruby Hill Carbon Kiln 1.2E+00 1.1E+00 7.3E-01 Ruby Hill EW Cells 8.9E-01 4.7E-01 1.4E+01 Ruby Hill Furnace 1.4E+00 2.7E-01 Ruby Hill Retort 1.8E-05 2.1E-05 1.4E-05 Gold Quarry AARL Carbon Kiln 3.5E+00 3.6E+00 3.9E+00 Gold Quarry AARL Carbon Kiln 7.5E-01 3.9E-01 5.6E-01 2.1E+00 2.9E+00 6 5 4.86EGold Quarry EW Cells / Barren Tank 4.5E-02 4.2E-02 4.6E-02 Gold Quarry EW Cells / Barren Tank 7.3E-02 6.7E-02 5.9E-02 5.6E-02 1.6E-04 6 5 2.72EGold Quarry Pregnant Tanks 2.3E-01 2.4E-01 3.7E-01 Gold Quarry Pregnant Tanks 3.4E-01 6.1E-02 1.3E+00 Gold Quarry Pregnant Tanks 3.8E-03 2.4E-01 5.4E-01 3.7E-01 1.4E-01 9 8 1.61EGold Quarry Refinery Furnaces 2.3E+00 5.3E-01 1.3E+00 Gold Quarry Refinery Furnaces 2.6E-02 6.6E-03 1.8E-01 7.2E-01 8.5E-01 6 5 1.42EGold Quarry Retort Stacks 1-3 3.7E-02 8.2E-02 4.3E-02 5.4E-02 5.9E-04 3 2 1.96EGold Quarry Retort Stacks 4-6 1.3E-01 9.8E-02 8.9E-02 1.1E-01 4.6E-04 3 2 1.52EGold Quarry Zadra Carbon Kiln 9.2E-01 6.0E-01 4.9E-01 Gold Quarry Zadra Carbon Kiln 5.6E-02 6.3E-02 7.9E-02 Gold Quarry Zadra Carbon Kiln 5.9E-02 7.1E-02 9.0E-02 2.7E-01 3.7E+00 1.0E-01 9 8 1.14E
17 

Appendix C. Mercury Emissions Data for the Non-Carbon Concentrate Affected Source (lb/ton co

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs DF 

Variance of unit average 

Coeur Rochester Refinery Furnace 6.0E-02 1.2E-01 2.3E-02 6.7E-02 2.3E-03 3 2 7.5E-04 Coeur Rochester Retorts #1 & #2 3.4E-03 9.2E-05 2.1E-03 Coeur Rochester Retorts #1 & #2 2.9E-04 1.5E-02 4.2E-03 4.2E-03 7.1E-02 3.2E-05 6 5 5.3E-06 Midas Operations Refinery Furnace #1 1.2E-01 5.4E-02 2.5E-02 Midas Operations Refinery Furnace #2 5.0E-02 1.6E-01 2.0E-02 Midas Operations Refinery Furnace 1 & 2 1.7E-01 2.2E-01 4.4E-02 Midas Operations Refinery Furnace 1 & 2 1.6E-02 2.6E-02 4.5E-02 8.7E-02 7.3E-03 6 5 1.2E-03 Midas Operations Retort A 2.3E-03 1.8E-03 1.5E-03 Midas Operations Retort A 1.3E-03 6.0E-02 3.4E-02 1.7E-02 6.2E-04 6 5 1.0E-04 Midas Operations Retort B 2.8E-04 1.1E-05 7.4E-06 Midas Operations Retort B 4.2E-03 4.5E-03 5.7E-03 2.4E-03 1.1E-01 6.8E-06 6 5 1.1E-06 

Average of top 5: 8.9E-02 2.0E-03 t DF: 22 Vb: 

t(.99): 2.51 
18 

Appendix D. New Source MACT Floors

ORE PRETREATMENT GROUP 

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs per 

unit 

DF (n-1) 

per unit 

Var of unit average 

Facility variance 

Goldstrike Roaster Mill #1 3.23E-07 5.03E-07 3.60E-07 Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.65E-04 2.65E-05 1.39E-05 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.35E-05 5.04E-06 7.85E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 8.61E-07 5.96E-07 5.17E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 1.79E-06 1.39E-06 2.65E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.19E-06 1.13E-06 2.65E-07 1.92E-05 3.83E-09 18 17 2.13E-10 

Goldstrike Roaster Mill #2 8.68E-06 4.71E-06 1.71E-06 Goldstrike 

South Dry grinding process and pre-heater - Mill 2 7.21E-06 5.24E-06 7.21E-06 

Goldstrike 

South Dry grinding process and pre-heater - Mill 2 8.52E-07 8.52E-07 3.93E-07 

Goldstrike 

South Dry grinding process and pre-heater - Mill 2 1.64E-06 8.52E-07 3.93E-07 3.31E-06 9.58E-12 12 11 7.98E-13 

Goldstrike Roaster 1 & 2 7.25E-05 5.71E-05 5.26E-05 Goldstrike Roaster 1 & 2 1.25E-05 1.25E-05 1.71E-05 Goldstrike Roaster Exhaust 1.95E-05 1.73E-05 1.32E-05 3.05E-05 5.47E-10 9 8 6.08E-11 Goldstrike Roaster #1 Quench Tank 4.35E-06 2.96E-06 2.87E-06 3.39E-06 6.86E-13 3 2 2.29E-13 Goldstrike Roaster #2 Quench Tank 3.55E-06 3.76E-06 3.32E-06 3.54E-06 4.72E-14 3 2 1.57E-14 Goldstrike Autoclave 1 2.59E-07 4.01E-07 4.70E-07 3.77E-07 1.16E-14 3 2 3.87E-15 Goldstrike Autoclave 2/3 6.57E-07 7.71E-07 5.50E-07 6.59E-07 1.23E-14 3 2 4.09E-15 Goldstrike Autoclave 4 1.42E-06 1.65E-07 1.81E-07 5.90E-07 5.21E-13 3 2 1.74E-13 Goldstrike Autoclave 5/6 1.42E-06 8.32E-07 4.62E-07 9.03E-07 6.24E-05 2.32E-13 3 2 7.72E-14 2.75 48 

Average DF = t = Vb = Vw = Vt = Facility 99% UP
19 

CARBON PROCESSES GROUP 

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs per 

unit 

DF (n-1) 

per unit 

Var of unit average 

Facility variance 

Round Mountain EW Cells 1.82E-02 7.93E-02 1.90E-02 3.88E-02 1.23E-03 3 2 4.09E-04 Round Mountain Furnace 1.49E-04 1.80E-03 1.77E-03 Round Mountain Furnace 3.49E-02 9.59E-03 1.85E-02 1.11E-02 1.83E-04 6 5 3.05E-05 Round Mountain Kiln and P/B Tanks 2.57E-03 2.86E-03 1.56E-03 Round Mountain Kiln and P/B Tanks 1.52E-02 1.02E-02 1.59E-02 8.05E-03 5.80E-02 4.33E-05 6 5 7.22E-06 4.47 12 

Average DF = t = Vb = Vw = Vt = Facility 99% UP

NON-CARBON CONCENTRATE GROUP 

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs per 

unit 

DF (n-1) 

per unit 

Var of unit average 

Facility variance 

Coeur Rochester Refinery Furnace 5.96E-02 1.17E-01 2.28E-02 6.65E-02 2.26E-03 3 2 7.53E-04 Coeur Rochester Retorts #1 & #2 3.43E-03 9.24E-05 2.13E-03 Coeur Rochester Retorts #1 & #2 2.93E-04 1.53E-02 4.20E-03 4.24E-03 7.08E-02 3.21E-05 6 5 5.34E-06 7.58 7 

Average DF = t = Vb = Vw = Vt = Facility 99% UP
20 

Appendix E. Beyond the Floor – Ore Pretreatment

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs 

per unit DF 

Var of unit average 

Facility variance 

Gold Quarry North Quench Circuit 1.35E-05 9.56E-06 1.37E-05 Gold Quarry North Quench Circuit 1.05E-05 1.33E-05 1.69E-05 1.29E-05 6.72E-12 6 5 1.12E-12 Gold Quarry Ore Preheater 1.27E-05 5.41E-06 4.53E-06 Gold Quarry Ore Preheater 2.63E-05 2.50E-05 1.54E-04 3.80E-05 3.32E-09 6 5 5.54E-10 Gold Quarry Ore Roaster 8.99E-07 6.97E-07 7.87E-07 Gold Quarry Ore Roaster 1.27E-06 1.61E-06 6.19E-07 9.80E-07 1.46E-13 6 5 2.44E-14 Gold Quarry ROTP: Ore Dry Grind 1.66E-06 2.06E-06 1.48E-06 Gold Quarry ROTP: Ore Dry Grind 1.50E-06 4.82E-06 1.75E-06 2.21E-06 1.67E-12 6 5 2.79E-13 Gold Quarry South Quench Circuit 1.67E-05 1.36E-05 9.55E-06 Gold Quarry South Quench Circuit 1.27E-05 1.46E-05 2.11E-05 1.47E-05 6.89E-05 1.54E-11 6 5 2.57E-12 5.58E-10 Goldstrike Roaster Mill #1 3.23E-07 5.03E-07 3.60E-07 Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.62E-04 2.62E-05 1.37E-05 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.35E-05 5.04E-06 7.85E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 8.50E-07 5.89E-07 5.10E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 1.77E-06 1.37E-06 2.62E-07 

Goldstrike 

North Dry grinding process and pre-heater - Mill 1 2.16E-06 1.11E-06 2.62E-07 1.89E-05 3.73E-09 18 17 2.07E-10 

Goldstrike Roaster Mill #2 8.68E-06 4.71E-06 1.71E-06 Goldstrike 

South Dry grinding process and pre-heater - Mill 2 7.21E-06 5.24E-06 7.21E-06 

Goldstrike 

South Dry grinding process and pre-heater - Mill 2 8.52E-07 8.52E-07 3.93E-07 

Goldstrike 

South Dry grinding process and pre-heater - Mill 2 1.64E-06 8.52E-07 3.93E-07 3.31E-06 9.58E-12 12 11 7.98E-13 

Goldstrike Roaster 1 & 2 7.25E-05 5.71E-05 5.26E-05 Goldstrike Roaster 1 & 2 1.25E-05 1.25E-05 1.71E-05 Goldstrike Roaster Exhaust 1.95E-05 1.73E-05 1.32E-05 3.05E-05 5.47E-10 9 8 6.08E-11 Goldstrike Roaster #1 Quench Tank 4.35E-06 2.96E-06 2.87E-06 3.39E-06 6.86E-13 3 2 2.29E-13 Goldstrike Roaster #2 Quench Tank 3.55E-06 3.76E-06 3.32E-06 3.54E-06 4.72E-14 3 2 1.57E-14 Goldstrike Autoclave 1 2.59E-07 4.01E-07 4.70E-07 3.77E-07 1.16E-14 3 2 3.87E-15 Goldstrike Autoclave 2/3 6.57E-07 7.71E-07 5.50E-07 6.59E-07 1.23E-14 3 2 4.09E-15 Goldstrike Autoclave 4 1.42E-06 1.65E-07 1.81E-07 5.90E-07 5.21E-13 3 2 1.74E-13 Goldstrike Autoclave 5/6 1.42E-06 8.32E-07 4.62E-07 9.03E-07 6.22E-05 2.32E-13 3 2 7.72E-14 2.69E-10 Lone Tree Autoclave 8.90E-05 5.03E-05 5.33E-05 6.42E-05 6.42E-05 4.64E-10 3 2 1.55E-10 1.55E-10 Twin Creeks Autoclave 1 1.66E-05 4.34E-05 3.06E-05 Twin Creeks Autoclave 1 2.35E-05 7.76E-05 8.70E-06 Twin Creeks Autoclave 1 7.07E-05 3.51E-05 3.25E-05 Twin Creeks Autoclave 1 6.40E-05 3.99E-05 3.29E-05 Twin Creeks Autoclave 1 2.99E-05 5.92E-05 7.98E-05 4.30E-05 4.92E-10 15 14 3.28E-11 Twin Creeks Autoclave 2 3.42E-05 1.64E-05 1.60E-05 Twin Creeks Autoclave 2 2.60E-05 1.49E-05 1.04E-05 
21 

Facility Unit Type 

Run 1 (lb/ton) 

Run 2 (lb/ton) 

Run 3 (lb/ton) 

Unit average (lb/ton) 

Facility total (lb/ton) 

Unit variance 

No. of 

runs 

per unit DF 

Var of unit average 

Facility variance 

Twin Creeks Autoclave 2 1.46E-05 2.72E-05 2.39E-05 2.04E-05 6.34E-05 6.01E-11 9 8 6.68E-12 3.95E-11 Jerritt Canyon Ore dryer 2.03E-05 2.03E-05 Jerritt Canyon Roaster West 3.40E-05 3.44E-05 3.96E-05 3.60E-05 9.53E-12 3 2 3.18E-12 Jerritt Canyon Roaster East 4.23E-05 3.58E-05 2.17E-05 3.33E-05 8.96E-05 1.11E-10 3 2 3.70E-11 4.02E-11  6.96E-05 t DF: 101 Vb: 4.25E-11 

t(.99): 2.36