Certified Mail No.: 7011 1570 0000 5861 5283Return Receipt Requested

Mr. Thomas Webb

U.S. EPA, Region IX

Planning Office, Air Division

75 Hawthorne Street (AIR-2)

San Francisco, CA 94105

RE: Information Request for Pending BART Determination

Dear Mr. Webb:

On January 10, 2013, ASARCO LLC (“Asarco”) received a request for information from the United States Environmental Protection Agency, Region IX (“EPA”) regarding the design, operation and past performance testing of the Hayden Smelter. EPA stated that the requested information was needed to ensure that its BART determinations for the Hayden Smelter for 802 and PM10 are supported by sound technical analyses. EPA’s request (in italics) and Asarco’s response to the requested items (in regular font) is as follows:

Information Needed to Make a BART Determination for SO,:

1. The average daily measurement for the SO2continuous emission monitoring system (CEMS) for the sulfuric acid plant at the Facility since January 1, 2005 in parts per million (ppm) and the total tons of SO2per day recorded by the SO2CEMS for the sulfuric acid plant since January 1, 2005. Please provide this information in an electronic format that may be edited by a spreadsheet program such as Excel or comparable software. Please also provide all SO2stack test data and relative accuracy test audits (RATAs) performed for the sulfuric acid plant for the period from January 2005 through December2012.

Information responsive to Item #1 is included on DVD #1, in the BART Determination — SO2 Item #1 folder (GEMs data and 2012 RATAs) and BART Determination — PMIO Item #2 folder (2012 SO2stack test data). RATAs for years 2005 through 2011 are included on DVD #3 and the SO2stack testing data for years 2005 through 2011 is included on DVD #2. Documentation of the EPA reference methodology utilized is included only once (year 2005) and is not replicated for each successive year.

2. The daily production of sulfuric acid by the sulfuric acid plant since January 2005 in tons. Describe the source of the data.

Information responsive to Item #2 is included on DVD #1, in the BART Determination — SO2 Item #2 folder. The data source is Asarco’s internal Daily Production Report. Asarco considers these data to be Business Confidential.

100 Hayden Avenue + P.O. Box 8 + Hayden Arizona 85135 Telephone: 520.356.7811

F’
Information responsive to Item #3 is included on DVD #1, in the BART Determination

— SO2 Item #3 folder. The data source is Asarco’s internal Daily Production Report. Asarco considers these data to be Business Confidential.

4. The quantity of concentrated ore processed by the smelter each calendar month since Januaiy 2005 in tons, along with the average daily percentage ofsulfur of the

concentrate. Describe the source of the data.

Information responsive to Item #4 is included on DVD #1, in the BART Determination

— SO2 Item #4 folder. The data source is Asarco’s internal Daily Production Report and Feed

% Sulfur spreadsheets. Copper concentrates comprise approximately 85% of the material smelted. Incoming concentrates are sampled and assayed for commercial/settlement purposes. Concentrates are blended with silica flux (approximately 10%) and byproducts (approximately 5%) in 6500-ton “mixes” that are the feed material to the INCO smelting furnace. The daily sulfur assays included are of the furnace feed and are grab samples for metallurgical spot checks only. Asarco considers these data to be Business Confidential.

5. Monthly material balances ofsulfur (as described in Specific Provision Ill. C. I and Attachment

D of Title

V Operating Permit 1000042) performed since Januaiy 2005, along with any support documents for each monthly balance.

Information responsive to Item #5 is included on DVD #1, in the BART Determination

— SO2 Item #5 folder. Monthly summary pages are included along with monthly sulfur balance worksheets. Asarco considers these data to be Business Confidential.

6. Copies of all actual SO2emissions calculations performed since Januaiy 1, 2005 for any copper smelting equipment that was submitted to any regulatoty agency. Include with

your response

a detailed description of all equations relied upon, including the identification of all data inputs into the equation,

a description of all emissions factors (EFs) rolled upon and their source, and all other methods or data relied upon to perform the calculations;

Information responsive to Item #6 is included on DVD #1, in the BART Determination

— SO2 Item #6 folder. The data source is Asarco’s Air Emission Inventory worksheets. SO2emissions from the INCO and converter furnaces primary gas streams are measured by the Acid Plant tail

gas CEM (S2). SO2emissions from the INCO furnace ventilation gas streams are measured by the ventilation gas CEM (SV). SO2emissions from the converter secondary gas streams are measured by the secondary hood CEM (SH). Flash furnace and converter fugitive SO2 emissions are quantified using emission factors derived from

a 1994/95 fugitive emissions study multiplied by operating hours. Anode furnace SO2emissions are quantified using the fugitive study factors. Anode burner emissions are quantified using AP42 estimations.
were 

in operation

before August 7, 1962 as defined under the Regional Haze Rule and the BART Guidelines.

Information responsive to Item #7 is included on DVD #1, in the BART Determination — SO2 Item #7 folder.

8. Provide the following information about the sulfuric acid plant:

a. the volume (liters) of catalyst in each catalyst bed; b. The diameter of the converter;

c. the type of catalyst (including trade-name) in each catalyst bed; d. the maximum volumetric capacity (liters) of catalyst;

a. the amount and type of catalyst replaced during each turn around since 2005; and

f. if ASARCO is using cesium promoted catalyst, provide the date the facility began using cesium catalyst

Information responsive to Item #8 is included on DVD #1, in the BART Determination — SO2 Item #8 folder.

9. Provide all vendor quotes for cesium promoted catalyst installation that the facility has received. Include any emission estimates provided by the vendors.

Information responsive to Item #9 is included on DVD #1, in the BART Determination — SO2 Item #9 folder.10. Provide the following information about process gas capture and treatment:

a. Indicate the maximum capacity of the acid plant to accept process off gases, including both airflow and inlet SO2concentration; b. Provide a detailed description of what happens to captured excess gas flow that would othe,wise be vented to the acid plant when that total gas flow exceeds the capacity of the acid plant;

c. Provide a detailed analysis of the capture efficiency of gases emitted from all

copper smelter process equipment; ci. Provide a schematic diagram showing which equipment at the Facility are captured and controlled or controllable by the acid plant;

e. Provide the following information about SO2emissions from the Pierce-Smith

Converters Secondary System:

i. Any and all data, in native format, on measurements or calculations of

SO2concentration in ppm of gas exiting the Secondary System on an hourly basis (or as frequent as measurements or calculations are/have

been taken/performed) since January 1, 2005;
lime for SO

v. For information provided under 8. c. i and 8. c. iv, a description of the underlying measurement and/or data used and any calculations performed.

f. For the emergency bypass vent that is part of the acid plant line, please respond

to the following requests:

i. Describe the location of the bypass in regard to any particulate matter (PM) controls (i.e. is it before or after each PM control);

IL Describe what happens to process off-gases vented through the bypass (L e. are they emitted directly to the atmosphere or controlled);

iii. Describe how the gas flow exiting the bypass is measured;

iv. In a chart format, since January 1, 2005, specify the total amount of gas vented through the bypass on a daily basis. Describe the source of the

data.

g. Provide a detailed description of SOrladen gas flow emitted from all copper smelter process equipment at the Facility (e.g. maximum and typical flow rates in actual cubic feet per minute (acfm), temperature, and SO2concentration in ppm), and whether it is currently vented to the acid plant, to other controls in place, or

to the atmosphere uncontrolled.

Information responsive to Item #10 is included on DVD #1, in the BART Determination — SO2

Item #10 folder.

Information Needed to Make a BART Determination for PM:

1. A description of existing PM control for all coppersmelter process equipment at the Facility.

Information responsive to Item #1 is included on DVD #1, in the BART Determination — PM10

Item #1 folder.

2. The average PM and PM10 emissions from any copper smelter process equipment at the Facility since January 2005 calculated in tons per calendar month and the assumptions and emission factors relied upon to perform the calculations. Please provide all PM and PM10 stack tests performed on any of this equipment.

Information responsive to Item #2 (including PM stack test data for year 2012) is included on DVD #1, in the BART Determination — PMIOItem #2 folder. PM stack test data for years 2005 through 2011 are included on DVD #2.
Item #3 folder.

4. A summary of all Method 9 opacity measurements taken at any part ofsmelter since January 2005, including a description of the location of the Method 9 reading, the results of the reading, and the name and affiliation ofthe individual who took the reading.

Information responsive to Item #4 is included on DVD #1, in the BART Determination — PM1O

Item #4 folder.

Pursuant to 40 CFR. § 2.203, Asarco asserts that the information provided in response to Questions 2 — 5 (DVD 1, BART Determination — S02 Item #2 through Item #5) constitute confidential business information as defined in 40 CFR § 2.201 (e), because release of this information could harm Asarco’s competitive position or release Asarco’s business proprietary information concerning its operating costs and efficiencies.

Please contact me at (520) 356-3284 or igarrity(asarco.com if you have any questions regarding this response.

JG/rcg

Enclosures —3 DVDs

Sincerely,

Technical Manager

RenvirolAlRlHayOpslSmelterlOtherCorres/EPABARTRFI1.10.1 3/AsarcoResponsel .25.13