**~**

# ASARCO 

# 'iii GRUPO MEXICO

July 11, 2013

Sent Email and Certified Mail Certified Mail No.: 7011 3500 0003 5438 8053 Mr. Thomas Webb U.S. EPA, Region IX Planning Office, Air Division 75 Hawthorne Street (AIR-2) San Francisco, CA 94105 Re: Response to·EPA Information Request dated June 27,2013 ASARCO LLC

- Hayden Operations Dear Mr. Webb: This letter responds to the U.S. Environmental Protection Agency, Region IX ("EPA") request to ASARCO LLC-Hayden Operations ("Asarco" or "Hayden") dated June 27, 2013, in which EPA seeks additional information to assist it in performing a best available retrofit technology ("BART") analysis pursuant to the regional haze rule and its pending partial approval and partial disapproval ofthe Arizona State Implementation Plan ("SIP"). In its letter, EPA states that it is evaluating whether planned upgrades at the Hayden Smelterfor purposes ofcomplying the 1-hour S02 National Ambient Air Quality Standards ("NAAQS") may meetthe requirements for BART. EPA has established a deadline for this response ofJuly 12, 2013 for all control options that were "considered" (defined as "contemplated

... through any planning process resulting in any written analysis") during Asarco's extensive design review for the Hayden Smelter's planned converter retrofit project ("CRP"), which is the projectthat Asarco has identified to assist in ensuring compliance with the 1-hour S02 NMQS. Asarco has provided the information that it can in the time available, but it has focused its efforts on those options that its design engineer, Gas Cleaning Technologies, LLC ("GCT"), identified as potentially applicable to the Hayden Smelter. Asarco is providing information responsive to each of EPA's requests. In addition, because EPA indicated that it is seeking to conduct its own BART determination, Asarco is providing a summary BART determination that it had started, but discontinued afterthe Arizona Department of Environmental Quality ("ADEQ") expressed its understanding that EPAwas looking to deferthe S02 BART determinations to the 1­ hour S02 NMQS implementation. We have included and slightly updated that

100 HaydenAvenue. P.O. Box 8 • Hayden Arizona 85135 Telephone: 520.356.7811Response to EPA Information Request dated June 27,2013 A8ARCO LLC-Hayden Operations July 11, 2013 Page 

### 2 discussion for EPA's consideration. Asarco acknowledges that it is not as complete as it could be, butthere was nottime to complete the analysis at Asarco's preferred level of detail in the time provided. 

### Asarco's Response to EPA Information Request Asarco has reprinted each part of EPA's information request in 

### boldfacetype. Asarco's response appears in regular type. 

### 1. Identifyand describe any design improvements, upgrades to existing equipment, or newequipmentwhich A5ARCO, oran entityworking on behalfofA5ARCO, has considered that have the potential to increase the quantity ofconverter502emissions thatare captured and vented to primary and secondary converter hooding. Asarco response: Asarco contracted with GCTto identify design improvements and upgrades to existing equipment or new equipmentthat have the potential to increase the quantity of converter 802 emissions that are captured and vented to primary and secondary converter hooding. GCT undertook a comprehensive study and considered the following modifications referred to as the Converter Retrofit Project or CRP:

• a converter process change to replace the existing five converters with three largerconverters, allowing one converter blowing instead oftwo at a time. • installing newtighter primary and secondary hoodstofit the new converters and provide greater capture efficiency. • sending secondary hood exhaustfrom the blowing converterto the acid plant to increase sulfurfixation. • modifying the converter primary gas system to suit the new converters and improve hood capture efficiency by installing individual spray coolers and a common ESP to'reduce system air infiltration. Both GCT and Asarco viewthe items above as one solution considered. The individual modi'fications cannot really be broken down into individual capture contributions since it is not practical to do anyone modification withoutthe other modifications. Asarco has also considered EPA's suggestion thattotal flow to the acid plant be increased. This solution is nottechnically appropriate forthe present equipment configuration because there is not sufficient strong 802gasto effectively operate additional acid plant capacity without increasing overall smelter capacity. The proposed CRP balances the existing strong 802gas generation capacitywith acid plant capacity, which is preferable to an unbalanced system. Because additional acid plant capacity would not be helpful, no furtherworkwas carried out on this alternative.

### Response to EPA Information Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 3

a. Foreach item identified in No.1 above, please includethe estimated quantityof

### 502thatwould be captured bythe primaryand secondary converter hoodsfollowing implementation ofsaid item. Please provide this.estimate in terms oftons/year, as well as maximum Ib/hr and maximum Ib/day. Asarco Response: The CRP is expected to increase the amount of S02 captured by the primary and secondary hoods on a PTE long-term basis by 58 tons/yrfrom 166,085 to 166,143 tons/yr. Most irrlportantly, it is expected to increase the amount ofS02 captured bythe primary and secondary hoods that is sent to the acid plantfor S02 control from 143,849 to 165,205 tons/yr. As noted above, the CRP is a holistic solution for sulfur capture and fixation that is not easily split among its various components. For purposes ofair permitting, Asarco has developed the following estimates. These estimates differ slightly fron1 the design specifications setforth in the preceding paragraph due to the interactions between the pieces ofequipment and rounding differences.

o 

### Total S02for converting and anode operations was estimated as follows. Using an assumed 60/40 split of sulfur loss in flash versus converting (and subsequent) operations, and deducting sulfurfrom anode operations, this results in the following emissions captured: • Total tons S02 converting and anode operations

# = 693,500 tons concentrate/yr * 0.3 S * 0.4 converting/anode ops fraction * 2 Sto S02 = 

### 166,440 tons/yr • Total tons S02 anode operations

# =600 anode tons/day *0.41 Ib/ton * 

### 365 days/yr * 

### 1ton/2000 Ibs

# = 44.9 tons/yr • Total tons S02 for converter operations = 166,440

- 44.9 = 166,395.1 tons/yr • Total tons S02 for converter secondary operations

# = 693,500 concentrate tons/yr * 0.3 S * 0.0025 converter secondary ops * 2 S to S02

# =1040.3 tons/yr • Total tons S02 for converter blowing operations

# =166,395.1

­ 1040.3 = 

### 165,354.8tons/yr

o 

### Approximate primary hood capture. After CRP implementation, the primary hood system should achieve aconservative design capture rate of 97%, with a short term worst case capture rate of93% and a best case rate approaching 100% (used 99.9%). 

### • Tons/year 

### = 160,394.2 (165,354.8 tons/yr * 0.97 capture) • Max Ib/hr: 63,400 (from GCT)Response to EPA Information Request dated June27, 2013 A8ARCO LLC-Hayden Operations July 11, 2013 Page 4

• Design Ib/hr (970/0): 36,619.7 (160,394.2 tons/yr * 2000 Ib/8760 hr) • Max Ib/day: 881,000 (from GCT) • Design Ib/day (970/0): 878,872.8 (36,619.7 * 24)

o Approxinlate secondary hood capture. After implementation, the secondary hood system should achieve a conservative design capture rate of97% for blowing emissions, with a shortterm worst case capture rate of93% for blowing emissions, and 900/0 capture ofconverter secondary operation emissions. • Tons/year: 5,748.1 ((165,354.8 * (1-0.97 primary capture) * 0.97 secondary capture (blowing errlissions) 

### + 1040.3tons * 0.90 capture (converter secondary» • Max Ib/hr: 4607.4 ((63,400 Ib/hr * (1-0.93) capture blowing Ib/hr * 0.99 capture) 

### + (1040.3 ton/yr converter secondary 

### * 0.9 capture 

### * 2000 Ibs/8760 hrs) • Design Ib/hr (970/0): 1,312.4 (5748.1 tons/yr * 2000 Ib/8760 hr) • Min Ib/hr (930/0): 1,267.0 (165,354.8 tons/yr

### * (1-0.97 primary capture) 

### * 0.93 secondary capture 

### * 2000 Ibs/8760 hrs) 

### + (1040.3 ton/yr convertersecondary * 0.9 capture * 2000 Ib/8760 hrs) 

### b. Foreach item identified in No.1 above, please also includethe estimated quantityof802

### thatwould be left uncaptured bythe primary and.secondary hoods following implementation ofsaid item. Please providethis estimate in terms oftons/year, as well as maximum Ib/hrand maximum Ib/day. Asarco Response: The CRP is expected to decreasethe amountof802 not captured bythe primary and secondary hoods on a PTE long-term annual basis by 58 tons/yrfrom 310to 252 tons/yr. Most importantly, it is expected to decreasethe amount of802 not captured by the primary and secondary hoods and senttothe acid plant by 21,356tons/yr "from 22,546to 1,190tons/yr, primarily by routing secondary hood emissions during blowing to the acid plant instead ofthe secondary hood baghouse. As noted above, the CRP is a holistic solution for sulfur capture and fixation that is not easilysplit among its various components. For purposes ofair permitting, Asarco has developed the following estimates. These estimates differslightly from the design specifications setforth in the preceding paragraph duetothe interactions between the pieces ofequipment and rounding differences.

• Approximate primary hood loss. After implementation, this should achieve a conservative design capture rate of970/0, with a shortterm worst case capture rate of930/0.Response to EPA Information Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11 , 2013 Page 5



### o 

### Tons/year: 4,960.6 (165,354.8 

### tons/yr* (1-0.97) (to secondary hoods) 

### o Max Ib/hr (at 93%): 2,642.7 (165,354.8 tons/yr * (1-0.93 capture) * 2000 

### Ibs/8760 hrs) 

### o Design Ib/hr (at 97%):**1,132~8** (165,354.8 

### tons/yr* 0.03 capture * 2000 

### Ibs/8760 hrs) 

### o Max Ib/day (at 930/0 for 3 hours): 31,716.9 (21 hr

### * 1,132.8 Ib/hr

### + 3 hr

### * 2,642.7Ib/hr) 

### o Design Ib/day (at 

### 97%): 27,187.2 (24 hr * 1,132.8 Ib/hr)

• Approximate secondary hood loss. After implementation, this should achieve a conservative design capture rate of 97%, with a shortterm worst case capture rate of93% plus 900/0 capture ofconverter secondary operations. 

### o 

### Tons/year: 252.8 (4960.6 

### tons/yr blowing 

### * (1-0.97 secondary capture) + 1040.3 * (1-0.9» (to tertiary) 

### o Max Ib/hr (at 930/0): 103.0 (1132.8 Ib/hr

### * (1-0.93 secondary capture) 

### + 1040.3 * (1-0.9) * 2000 

### Ibs/8760 hr) 

### o Design Ib/hr (at 97%): 57.7 (252.8 

### tons/yr* 2000 

### Ibs/8760 hrs) 

### o Max Ib/day: 2,090.7 (103.0 Ib/hr

### * 3 

### hr/day

### + 57.7 Ib/hr

### * 21 

### hr/day

### + 1040.3 ton/yrsecondary * (1-0.9 secondary capture) * 2000 

### Ibs/8760 hr * 

### 24 hr/day) o Design Ib/day (at 970/0): 1,385.2 (252.8 

### tons/yr* 2000 

### Ibs/8760 hr* 24 

### hr/day)

c. Foreach item identified in No.1 above, please includethe supporting calculations used to determinethe quantityof

### 502 captured bythe primaryand secondary converter hoods following the implementation ofsaid item. Ifsuch calculations are available in an electronicformat, such as a spreadsheet program like Excel or process simulatoroutput, providethe supporting calculations in said electronicformat. Asarco Response: Asarco's revised spreadsheet page for S02 emissionsforthe pending CRP permit application (as revised) is attached. This provides the basic numbers used above. The 93% values were derived by substituting them in lieu ofthe 970/0 values shown. Calculations are shown above. This was done by hand. Some numbers were provided by GCTand are mostly identified as such. As noted above, the CRP is a holistic solution for sulfur capture and fixation that is not easily split among its various components. For purposes ofair permitting, Asarco has developed the preceding estimates. These estimates differ slightlyfrom the design specifications setforth in the preceding paragraphs dueto the interactions between theResponse to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 6 pieces ofequipment and rounding differences. They also differ slightly from those previously submitted to AOEQ and will be updated in a supplemental application. 

### d. Foreach item identified in No.1 above, please provide the purchased equipmentcost, installation costs, and operating and maintenance costs associated with said control option. Asarco Response: The total installed (supply plus installation) cost forthe considered solution is $95,700,000. Operating and maintenance costs are expected to be similarto current operation. 

### 2. Identifyand describe any design improvements, process improvements, or newequipmentwhich A8ARCO, oran entityworking on behalfofA8ARCO, considered that have the potential to capture converter

### 802 emissionsthat are notable to be captured bythe primary orsecondary converter hoods. Asarco Response: For improvements to capture S02 emissions that are not able to be captured by the primary and secondary converter hoods, we have considered partial enclosure ofthe converter aisle and installation oftertiary hoods along the roofline above thethree new converters that will be exhausted directlyto the smelter stack using 

### 10 fans.



### a. Foreach item identified in No.2above, please include the estimated quantityof

### 802thatwould be captured by said item. Please provide this estimate in terms oftons/year, as well as in terms of Ib/hrand maximum Ib/day. Asarco Response: Asarco did not separately consider partial building enclosure and tertiary ventilation, but looked atthem as a combined system to improve emissions capture from converter fugitives that cannot be captured bythe primary and secondary hooding systems. On an annual basis, the newtertiary hoods are expected to capture 240 tons/yr, or 95% of the S02thatwould escape the new primary and secondary hoods. The maximum daily capture rate would be 2091 Ib/day, with a maximum hourly capture rate of 103 Ib/hr. For air permitting purposes, Asarco has estimated the amount ofS02thatwould be captured by the building enclosure and tertiaryventilation are as follows:

• Tons/year: 240tons/yr ('from GCT) • Max Ib/hr: 103 Ib/hr (from GCT)Response to EPA Information Request dated June 27,2013 A8ARCO LLC-Hayden Operations July 11, 2013 Page 7

• Design Ib/hr (97% secondary hood): 54.8 (240 tons/yr

### * 2000 Ibs/8760 hr) • Max 

### Ib/day (at 93%): 2091 Ibs/day (from GCT) 

### b. Foreach item identified in No.2above, please include the estimated quantity of

### 502 

### thatwould be left uncaptured bysaid item. Please providethis,estimate in terms oftons/year, as well as in terms of maximum Ib/hrand maximum Ib/day. Asarco Response: Asarco did not separately consider building enclosure and tertiary ventilation, but looked atthem as a combined system to improve emissions capture from converterfugitives that cannot be captured by the primary and secondary hooding systems. On an annual basis, the expected rate of802emissions not captured bythe newtertiary hoods would be 12 tons/yr, or 5% ofthe 802that would escapethe new primary and secondary hoods. The maximum daily 802 emissions rate not captured bythe tertiary hoods would be 105lb/day, with a maximum hourly 802 rate not captured bythe tertiary hoods of 17 Ib/hr. For air permitting purposes, Asarco has estimated the amount of802thatwould not be captured by the building enclosure and tertiary ventilation as follows:

• Tons/year: 12 tpy (from GCT) • Max Ib/hr (93% secondary hood): 17 Ib/hr (from GCT) • Design Ib/hr (97%): 1132.8 Ib/hr * (1-0.97) control * 0.05 not captured 

### + 1040.3 ton/yr secondary 

### * (1-0.9 control) 

### * 0.05 not captured 

### * 2000 Ibs/8760 hr

# = 2.9 Ib/hr • Max Ib/day: 105 Ib/day (from GCT)



### c. Foreach item identified in No.2above, please includethe supporting calculations used to determinethe quantity of

### 502 captured by implementation ofsaid item. Ifsuch calculations are available in an electronicformat, such as a spreadsheet program like Excel, orprocess simulatoroutput, providethe supporting calculation in said electronic format. Asarco Response: Asarco's revised spreadsheet page for 802 emissions for the pending CRP is attached. This provides the basic numbers used above. The 930/0 values were derived by substituting them in lieu ofthe 970/0 values shown. This was done by hand. Other values were provided by GCT. Calculations are shown in the answers above, where available.Response to EPA Information Request dated June 27,2013 A8ARCO LLC-Hayden Operations JuIy 11, 2013 Page 

### 8 As noted above, the CRP is a holistic solution for sulfur capture and fixation that is not easily split among its various components. For purposes ofair permitting, Asarco has developed estimates. These estimates differslightlyfrom the design specifications set forth in the preceding paragraphs due to the interactions between the pieces of equipment and rounding differences. 

### d. Foreach item identified in No.2above, please provide the purchased equipmentcost, installation costs, and operating and maintenance costs associated with said control option. Asarco Response: The total installed (supply plus installation) cost forthe CRP solution is $13,400,000. Annual operating and maintenance costs are expected to be approximately $300,000. 

### 3. Please identifyand describe any control options thatASARCO considered forcontrolling 

### 502 emissionsthatare captured by items identified in No.2 above. Asarco Response: For 802 control options for Item 2, A8ARCO has not considered any 802 control options forthe newtertiary hoods due to the very low 802 concentration and emissions rate.



### a. Foreach control option identified in No.3 above, please include an estimate ofthe control effectiveness ofthe option, aswell as an estimate ofthe post-control 

### 502emission rate. Please provide these estimates on a long-term (annual) basis, as well as on ashort

..term basis (maximum 1-hraverage and maximum dailyemission rate). Asarco Response: Not applicable. 

### b. Foreach control option identified in No.3 above, please includethe supporting calculations used to determinethe post-control 

### 502 emission rate. Please provide this information in an electronicformat that may be edited bya spreadsheet program such as Excel or comparable software. Asarco Response: Not applicable.Response to EPA Information Request dated June 27, 2013 A8ARCO LLC-Hayden Operations July 11 ,2013 Page 9



### c. Foreach control option identified in No.3above, please provide the purchased equipmentcost, installation costs, and operating and maintenance costs associated with said control option. Asarco Response: Not applicable. 

### 4. Identify and describe any control option thatASARCO, oran entityworking on behalfofASARCO, considered forcontrolling S02 emissions captured and vented to secondary converter hooding. Asarco Response: For 802 control options for controlling 802 emissions captured and vented in secondary converter hooding, the considered solution in the CRP is to send the secondary hood exhaust on the blowing converterto the existing acid plant for sulfurfixation as included in Item 1.



### a. For each control option identified in No.4above, please include an estimate ofcontrol effectiveness, as well as an estimate ofthe postcontrol S02 emission rate. Please provide these estimates on a long· term (annual) basis, as well as on a short-term basis (maximum 1·hr average and maximum dailyemission rate). Asarco Response: The CRP solution is expected to control 84% ofall 802captured by the converter secondary hoods, reducing the average 802emissions rate from the secondary baghouse from 5,748 to 936 tons/yr. The maximum daily emissions rate from the secondary baghousewould be 5,000 Ib/day, and maximum hourly emissions rate would be 360 Ib/hr. 

### b. Foreach control option identified-in No.4above, please includethe supporting calculations used to determinethe post-control S02 emission rate. Please provide this information in an electronic formatthat may be edited bya spreadsheet program such as Excel orcomparable software. Asarco Response: 8ee attached spreadsheet.Response to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 10



### c. Foreach control option identified in No.4above, please providethe purchased equipmentcost, installation costs, a.nd operating and maintenance costs associatedwith said control option. Asarco Response: The costfor implementing this solution is included in the Item 1 cost ($95,700,000) and cannot be done independent ofthe Item 1 solution. 

### 5. Identifyand describeany improvements or upgrades tothe acid plantthat A8ARCO, oran entityworking on behalfofA8ARCO, considered for reducing 802 

### emissions from the acid plant.

Asarco Response: For improvements to the acid plant, ASARCO has considered no modificationsto reduce S02 emissionsfrom the acid plant. As briefanalysis is presented in the preliminary BART analysis presented below.



### a. Foreach item identified in No.5 above, please includethe estimated 802 

### emission rate ofthe acid plantfollowing implementation ofsaid item. Please providethis estimate in terms oftons/year, as well as in terms of maximum Ib/hrand maximum Ib/day. Asarco Response: See preliminary BART analysis below. 

### b. Foreach item identified in No.5above, please includethe supporting calculations used to determinethe estimated 802 emission rate associated with implementation ofsaid item. Ifsuch calculations are available in an electronicformat, such as a spreadsheet program like Excel, or process simulatoroutput, providethe supporting calculations in said electronic format. Asarco Response: See preliminary BART analysis below.



### c. Foreach item identified in No.5 above, please provide the costs, if estimated, ofpurchasing, implementing, and operating said item. Asarco Response:Response to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 11

See preliminary BART analysis below. 

### 6. For each unitcomprising the BART-eligible source thatwas included in model runs used to determine ambientS02 impacts, please listthe source parameters thatcharacterized the unitin the model runs, including: a. Source location in either UTM coordinates or latitudeand longitude. Please specifythe datum. b. Base elevation. c. For pointor pseudopointsources, includethe stack height, stack diameter, exhausttemperature, and exitvelocity. d. Forarea sources, includethe initial vertical dimension, orthe initial depth, ofthe area source plume, the release heightabove ground, and the dimensions ofthe area source (eitherx-side and y-sidefor polygons, or radius forcircular). e. Forvolume sources, includethe initial lateral dimension, initial vertical dimension, and release height. f. In instanceswhere multipleversions ofsource parameters may have been used to characterize a unit, includeall versions ofthe source parameters. Asarco Response: Asarco treated all emissions from the converter aisle (converters #1-#5) and anode furnaces (#0-#2) as being emitted from the BART-eligible units (converters #1, #3-#5 and anode furnaces #1 and #2) because notall converters or anode furnaces can operate at a single time, yet it is conceivable that only BART-eligible units could be operating at a single time (although even then it is unlikelythatfour converters would be in operation). With this understanding, Asarco relied upon the original WRAP modeling work (to verify archived model accuracy) and then used revised values. The original WRAP model inputs are enclosed as Attachment 6-1. Note thatthe X and Y coordinates are given in Lambert Conformal Conic (LCC-X) km and Lambert Conformal Conic (LCC-Y) km respectively. Based on the best information available to Asarco, the LCC-X and LCC-Y were derived from UTM 12 NAD 83 coordinate system. It appears that ENVIRON (the WRAP modeler) converted the emissions points listed as "Fugitive" to equivalent circular diameters ofapproximately the same size shown in the revised Asarco model inputs. The revised Asarco model inputs are enclosed as Attachment 6-2. 

### ASARCO Preliminary S02 BART Analysis A. Process Description

### Response to EPA Information Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 12

Production of copper from sulfide ores, typically containing less than 1 % 

### copper, requires beneficiation of the ore through crushing, grinding and froth flotation. Such separation process liberates copper-bearing minerals from the host rock and yields a mineral-enriched material that typically contains 20 to 30 percent copper, commonly referred to as "concentrate". The concentrate must be further processed by smelting to produce usable copper. The Hayden copper smelting process includes 3 steps: smelting concentrate in the INCO Flash Furnace to produce molten matte, converting matte to blister copper, and fire refining blister copper to produce anodes for electrolytic refining. Concentrate is combined in the bedding plant with siliceous flux and recycled process materials, and the resultant furnace feed is dried in the fluid-bed dryers. The dried feed is introduced, along with combustion oxygen, into an INCO oxygen flash furnace where iron and sulfur in the feed combust, or "flash" in the high-temperature, oxygen-rich furnace atmosphere. The resultant molten material collects at the bottom of the furnace as a "bath" where it naturally separates into two layers, matte and slag. This smelting process eliminates approximately 60 percent of the iron and sulfur in the concentrate. Iron oxidizes and combines with silica flux to form a molten slag, and sulfur oxidizes to sulfur dioxide gas (S02), which is sent through a gas cleaning system and then to the acid plantto be made into sulfuric acid. The copper-rich layer, matte, is tapped from the furnace and directed via ventilated launders into ladles that are staged below the furnace floor. Matte**typic~lIy** 

### contains 45 to 65 percent copper. Once the ladles are filled, they are moved into the converter aisle for crane transfer to the converters. The slag is skimmed into a slag potfor movementto the slag cooling or deposition area. The Hayden Smelter utilizes five Peirce-Smith furnaces to convert matte to blister copper. Overhead cranes transfer the matte-filled ladles from the flash furnace to the converters. Converting consists of blowing air or oxygen-enriched air through the molten bath and adding siliceous flux and other copper-bearing materials at various times during the process to control bath temperature and to facilitate the chemical reactions that allow the formation of an iron/silica slag. A typical cycle converts ten ladles ofmatte to four ladles of blister copper 

### (980/0 to 

### 99% pure copper). Each converter at the Hayden smelter is equipped with primary and secondary hooding systems. The primary hooding system is designed to capture the S02-containing gases that are evolved while the converters are blowing or "rolled-in". These gases are routed through a gas cleaning system to remove particulate matter before reporting to the acid plant for conversion to sulfuric acid. The acid plant tail gas reports to the center ofthe facility's 1,OOO-foot stack. The secondary hooding system is designed to capture fugitive gases and particulates that escape the primary hoods or are emitted when the converter is "rolled-out" for skimming and charging. Gases that are collected by the secondary hoods are directed to a baghouse for particulate matter removal before being exhausted to the atmosphere via the annulus ofthe facility's 1,OOO-foot stack.Response to EPA Information Request dated June

### 27,2013 ASARCO LLC-Hayden Operations July 

### 11,2013 Page 

### 13

B. BART-ELIGIBLE UNITS ANALYSIS Based on EPA's Guidelines forBARTDeterminations Underthe RegionalHaze Rule, 1 ASARCO LLC ("Asarco") has reviewed the Hayden Smelter's individual primary smelting units to determine whetherthey are BART-eligible consistentwith the Act's and the Guidelines' requirements. Underthe Act and Guidelines, once a source is determined to be BART-eligible, the start-up dates ofeach BART emission unit must be identified.2 In general, a unitthatwas "in existence" on August

### 7, 1977, but not "in operation" before August

### 7, 1962, is a BART-eligible unit. The best general reference for the construction dates ofthe potentially BART-eligible equipment atthe Hayden Smelter is Attachment "C" to Asarco's Title V Operating Permit No. 

### 1000042. This permit lists the following equipment and dates: Unit Installation Date BART-eligible? 

### 2 x Concentrate Dryers 

### 1983 No, post 

### 1977 1 x Inco Flash Furnace 

### 1983 No, post 

### 1977 

### 5x Converters Various See below 

### 2 xAnode Furnaces 

### (#1 and 

### #2) 1971 Yes 1 xAnode Furnace 

### (#0) 2001 No, post 

### 1977 Acid Plant 

### 1983 No, post 

### 1977 The concentrate dryers, INCOflash furnace and acid plantwere installed as part ofa single modernization effortthat occurred afterthe BART applicability date and were, accordingly, not "in existence" on August

### 7, 1977 as thatterm is defined in the BART regulations and Guidelines.3 Asarco agrees that anode furnaces 

### #1 and 

### #2 were installed in 

### 1971, operating no later than 

### 1973, and are BART-eligible units.4 Anode furnace 

### #0 was installed in 

### 2001 and is not BART-eligible because itwas not "in existence" during the BART-eligibility period.

### s The converters present a more complex picture. Based on a historical narrative authored by E. S. Godsey, Asarco commenced operation ofthe Hayden Smelter in 

### 1912 with two converters, and operated with three converters ofvarious sizes and configurations between the years of 

### 1913 and 

### 1966. Recent research ofengineering and purchasing records indicates that one ofthe existing converters, 

### #2, pre-datesthe

140C.F.R. Part 51, App. Y [hereinafter Guidelines]. Asarco notes thatthe Guidelines are guidelines onlyandthat the Stateretains discretion to weighthe five BARTfactors as it sees fit. Guidelines, §I.F.l. 2 Guidelines, §II.A.2. 3Permit 1000042, Attachment "C";seealso Guidelines, §II.A.2. 4Permit 1000042, Attachment "C"

.. sPermit 1000042, Attachment "C";seealso Guidelines, §II.A.2.Response to EPA**Informa~ion** Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 14 The converters present a more complex picture. Based on a historical narrative authored by E. S. Godsey, Asarco commenced operation ofthe Hayden Smelter in 1912 with two converters, and operated with three converters ofvarious sizes and configurations between the years of 1913 and 1966. Recent research ofengineering and purchasing records indicatesthat one ofthe existing converters, #2, pre-dates the BART-eligibility period, and that one converterwas added and three converters were replaced with larger units during the BART-eligibility period. Atthis time, Asarco believes thatthe following units are BART-eligible:

• Converter #1

- Installed in 1966. BART-eligible. • Converter #2

- Purchased and installed in 

### 1949/50 and still operating. Not BARTeligible. • Converter #3

- Replaced a 10'x26' unitwith a 13'x33' unit in 1965. BARTeligible. • Converter#4

- Replaced a 13'x30' unitwith a 13'x33' unit in 1966. BARTeligible. • Converter#5

- Replaced a 13'x30' unitwith a 13'x35' unit in 1975. BART­ eligible. A copy ofthe purchase orderfor converter#2 is attached. Accordingly, anodefurnace #1, anode furnace #2, converter #1, converter#3, converter #4 and converter#5 are the only BART-eligible units. 

### C. SUBJECTTO BARTANALYSIS Asarco acknowledges thatADEQ and the Western Regional Air Partnership (WRAP) modeled the Hayden Smelter during development ofthe Section 308 Regional Haze State Implementation Plan (SIP). Based on that modeling, the Hayden Smelterwas shown to be "subjectto BART" because it caused a visibility impact ofgreaterthan 0.5 dv atthe most affected Class I area. While Asarco believes thattheWRAP modeling effort used inappropriate potential to emit, ratherthan "steady-state operating conditions during periods ofhigh capacity utilization" as recommended bythe 

### Guidelines]6Asarco concedes thatthe Hayden Smelter's converters #1, #3, #4, #5 and anode furnaces #1 and #2 are subjectto BART for S02. NOx and PM BART were previously addressed in prior State and EPA actions. D. 

### S02 BARTANALYSIS 

### Step 1: Identifythe Existing Control Technologies in Use atthe Source According to Air Quality Permit 1000042, issued by ADEQ on October 9, 2001, the Asarco Hayden smelter has installed and operates the following control technologies on

6 Guidelines, §IILA.3, Option 1 (2).Response to EPA Information Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 15 the equipment subject-to-BART: Converters #1-#5 Primary Hoods routed to Acid Plant Secondary Hoods routed to Secondary Hood Baghouse Anode Furnaces #1-#2 No controls Substantial upgrades to the air pollution control equipment for the BART-eligible units have been installed since August 1977. According to ADEQ's 

### Final Hayden Sulfur Dioxide NonattainmentArea State Implementation and Maintenance Plan, dated June 2002, prior to 1971, all smelting operations process gasses from the facility were emitted into the atmosphere after electrostatic precipitators removed the particulate matter from the gases. In 1971, however, the company installed an acid plant as an S02 control for primary converter gases. According to sulfur balance information from the time period, S02 en1issions from the facility were well in excess of 100,000 tons per year. In 1983, the company undertook a series of additional improvements, including the replacement of twelve multiple-hearth roasters and two reverberatory furnaces, replacing them with an INCO Flash smelting furnace. Atthe same time, Asarco installed a 650 ton per day oxygen plant that would enrich the smelting process gasses. Based upon this addition, the company was able to replace the existing single contact acid plant with a new double-contact acid plant. The emissions reductions resulting from these projects were estimated to be 63,584 tons per year of S02. According to ASARCO's calculations, the double-absorption acid plant recovers 99.81 percent ofthe S02 emissions that arevented to it. In 1998, ASARCO made a modification to the smelter's existing gas handling system, and installed an $18.4 million wet gas handling system. This modification allowed the flash furnace off gas to be treated at temperatures that are less than 2000 F, approximately 400 0 F less than the previous system. Due to the lower temperatures, the volume of gas being vented from the flash furnace was reduced, enabling the acid plant to provide additional ventilation to the converters. This additional ventilation allowed the secondary hoods to capture more S02 emissions from the converter building. 

### Steps 2-3: (2) Identifyall available retrofitcontrol technologieswith practical potential forapplication to the specific emission unitforthe regulated pollutant underconsideration; and (3) eliminate all technically infeasible control technologies. In the Section 308 Regional Haze SIP, ADEQ determined that the Kennecott Utah

### Response to EPA Information Request dated June 27,2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 16 Copper Corporation's continuous production of blister copper is a fundamentally different process from the process employed by Asarco's Hayden Smelter. ADEQ has also determined that BART does not contain a requirement that the source be redesigned when the Agency considers the available control alternatives. As a result, ADEQ concluded that it is not necessary to consider the use of Kennecott Utah Copper Corporation's process as a potential BART alternative. Section 308 SIP, 

### § XII.C, at 88. EPA concurred with this determination. 77 Fed. Reg. 75704, 75726 (Dec. 21, 2012). Asarco also concurs. 

### Evaluation 

### ofpossible controltechnologies. The following technologies are potentially available for S02 control from the Converters and Anode Furnaces: Double contact acid plant (existing) Wetscrubbing Dry scrubbing According to ADEQ's 

### Final Hayden Sulfur Dioxide Nonattainment Area State Implementation and Maintenance Plan, dated June 2002, the process changes and installation of air pollution controls through the years has resulted in an increased overall S02 control efficiency at the Hayden primary copper smelter. Since the 1970s, the S02 control rate has risen from approximately 32%) to approximately 42% with the installation ofthe double contact acid plant in the mid-1980s, to approximately 92%) as a result ofthe wet gas handling system and related improvements. Conversely, estimated S02 emissions from the facility fell from approximately 200,000 tons per year in the early 1970s, to less than 25,000 tons peryear at the current time. Asarco will considerthe possible applicability ofadding scrubbing to the Acid Plant tail gas, the Secondary Hood Baghouse exhaust, and tertiary ventilation gases in this preliminary BART analysis. 

### Technicalfeasibility. All ofthe technologies identified above werejudged to be potentially feasible ofapplication to the Converter primary gas stream, exceptfor dry scrubbing. There is no known application ofdry scrubbing downstream ofan acid plant and the wet, acidic atmosphere would render a baghouse (used to collectthe dry scrubbing sorbent) ineffective. Dry scrubbing is thus deemed technically infeasible for installation post-acid plant. In addition, dry scrubbing is deemed technically infeasible for application as a supplementary control forthe existing Secondary Hood Baghouse because ofthe conversion of reagents to gypsum and subsequent interferencewith resmelting baghouse dusts. Acid plants are nottechnically feasible forthe Converter secondary gas stream, the Anode Furnaces, or atertiary ventilation system due to the low concentration ofS02 present (estimated to be well below 

### 1 % ).Response to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 17 Wet scrubbing and dry scrubbing arejudged techniC(ally infeasible for tertiary ventilation ofthe Converters orfor the Anode Furnaces because the concentration is too low «20 ppm S02) for effective scrubbing. 

### Step 4. Ranking ofControl Effectiveness. Asarco's technical experts were not able to identify any control technologythatwould result in more substantial S02 emission reductions than the present double absorption, double contact acid plant. While Asarco has identified a change in convertertechnology that could result in decreased S02 emissions-replacement ofthe currentfive variablysized converters with three identically-sized converters to allow more balanced operation-wholesale replacement ofthe process source is inconsistentwith "best available retrofit technology," which unambiguously allows only control technologythat "retrofits" existing process equipment, not replacing existing process equipment. Similarly, changing the Hayden smelterfrom a five converter operation to a three converter operation constitutes a redesign ofthe source. Redesign is not required. 7 Because the double contact acid plant is the best available technology and it is already applied, no further consideration ofwet scrubbing ordryscrubbing, which cannot achieve equivalent results, is required.

### s The remaining technologies under consideration are: Primary Off-gas: Double ContactAcid Plant, 98.8% control (already in place) Tail gas wet S02 scrubbing (supplemental control), 

### 90% Secondary Off-gas:Wet S02 scrubbing, 

### 85% control 

### Steps 5-7. (5) Evaluate energy and non-airqualityenvironmental impacts; (6) Evaluate visibility impacts; and (7) select BART. In these steps, Asarco evaluates energy, non-airquality environmental impacts, cost, and visibility impacts and based upon that analysis, recommends BART. 

### Primary Off-gas. Asarco already has in place the most effective technology, a doublecontact acid plant. In the proposed rule to approve in part and disapprove in partthe Arizona Regional Haze SIP, EPAquestioned whetherthe Hayden Acid Plantwas operating atoptimum levels and questioned whether control levels atother industry acid plants might achieve higher levels. Finally, EPAquestioned whetherADEQ's application of NSPS Subpart P adequately addressed all gases putatively controlled by Subpart P. Asarco responded to those questions in its comments. 

### SeeAsarco

740 C.F.R. Part 51, App. 7, § IV.D.l(5). 8 Guidelines, §IV.D.I(9)Response to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 18 comments, dated March 6, 2013, a copy ofwhich is included in Attachment BART-1 and which is hereby incorporated into this analysis. In its analysis, Asarco**det~rmined** thatthe double contact acid plant remains the best control technology for control ofstrong acid gas streams; that othertypes ofacid plants do not provide meaningful guidance on whatAsarco should be able to achieve based on differences in the nature ofthe variousprocesses, inputs, and operating variabilities (as EPAalso determined in the Background Information Documentfor NSPS Subpart P), and thatthe NSPS Subpart P limit of650 ppm. represents the best limit that is consistently achievable given natural process variability and degradation ofcatalysts overtime. Because Asarco believes that the uncontroverted record is clearthat a double contact acid plant is the best control for a strong gas stream, further analysis is not required. Asarco will continue to maintain and operate is double contact acid plant consistent with the enforceable limits and monitoring conditions of NSPS Subpart P, which it hereby recommends be adopted as BART. Asarco did considerthe possibility ofadding a tail gas scrubberto the acid plant. The estimated cost ofsuch a unit is approximately $13 million. In addition, an annual $350,000 in operating expense is anticipated. Based upon these expenses, which amountto an annualized cost of$1,000,000, and assuming thatthe wet scrubbing achieved 

### 90% control ofthe 507 tons emitted from theAcid Plant9 (only roughly 240/1060 ofthis S02, or 114.8 tons is attributable to BART-eligible units),10 the cost exceeds $9500/ton forthe 103 tons removed. Wet scrubbing would require approximately 75 gallons/minute ofwater, amounting to roughly 121 acre-feet/annum, a considerable expenditure ofwater in an arid environment. Similarly, wet scrubbing would generate large volumes ofwastewater and sludge, requiring substantial additional expense to manage and treat. Asarco did not evaluate the cost in $/dv given the high cost on a $/ton basis. Based on all ofthese considerations, Asarco believes thatthe Acid Plant represents BARTfor the primary off-gas stream because it represents the best currenttechnology and that add-on technologies do not achieve substantial visibility improvements, yet represent a substantial increase in operating cost, consume valuable landfill space, and, forwet scrubbing, large qU,antities ofprecious water in an arid environment. Asarco finds thatthe costs and landfill capacity consumption outweigh the small visibility gain. 

### BART istherefore selected as no further control beyond the existing double contactacid plantat NSPS Subpart P limits of650 ppm. Additionally, Asarco recommends thatthe NSPS Subpart P continuous emissions monitoring, recordkeeping and reporting provisions be adopted to ensure adequate enforceability.

92002 Emissions from 2002 Emissions Inventory. Highestduring 3 yearperiod2001-2003, 10 AP-42, Chapter 12.3, Table 12.3-3Response to EPA Information Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 19 $28 million, exclusive of**th~** cost ofa boosterfan and possibly a newor modified stack to handlewet discharge gas. In addition, an annual $8-9 million in operating expense is anticipated. Based upon these expenses, which amountto an annualized cost of$9.4 million (assuming only $8 million in annual cost), and assuming thatthe wet scrubbing achieved 85% control ofthe 16,391 tons emitted from the Secondary Hood Baghouse,11 or 13, 932 tons/year, the cost exceeds $675/ton. Wet scrubbing would require approximately 75 gallons/minute ofwater, amounting to roughly 121 acre-feet/annum. Wet scrubbing would generate large volumes ofwastewater and sludge, requiring substantial additional expense to manage and treat. Further, because Asarco currently recycles these dusts to the process, either additional cost to drythe material and return it to the process orto dispose ofthe material, including lost copper recovery, would need to be added to the cost ofcontrol. Alternatively, Asarco is working on the CRP. The CRP would reduce emissions to the Secondary Hood Baghouseto 936.2 tons (potential to emit) versus 2,459 tons/year (projected actual) emissionsfrom the wet scrubbing alternative. The CRP is able to achieve additional reductions by balancing converter gas generation betterwith flash furnace gas generation and fully utilizing existing Acid Plant capacity. The CRP constitutes a "beyond BART" control because it requires a change in plant con'figuration (replacement ofthe five existing converters with three new, slightly largerconverters to allowthe balancing described above). Asarco did not conduct modeling ofthevisibility impact in light ofthe higheremissions reductions anticipated from the proposed CRP. In light ofthe proposed CRP, which would eliminate the need forthe wet scrubbing, and after considering the adverse energy, water and sludge impacts caused by implementing a wet scrubbing system, Asarco believes that the existing Acid Plant represents BARTforthe primary and secondary off-gas streams because it represents the best currenttechnology and that add-on technologies do not achieve substantial visibility improvements, yet represent a substantial increase in operating cost, consume valuable landfill space,

## anq, forwet scrubbing, large quantities ofprecious water in an arid environment. Asarco 'finds thatthe costs and landfill capacity consumption outweigh the likely visibility gain. 

### BART is thereforeselected as no further control beyond the existing double contactacid plantat NSPS Subpart P limits of650 

### ppm. Additionally, Asarco recommends thatthe NSPS Subpart P continuous emissions monitoring, recordkeeping and reporting provisions be adopted to ensure adequate enforceability. Tertiary Ventilation. 

### Given the absence ofanytechnicallyfeasible S02 controls, BART is determined to be noadditional control.

112002Emissions from 2002 Emissions Inventory. Highestduring 3yearperiod2001-2003.

### Response to EPA Informa·tion Request dated June 27, 2013 ASARCO LLC-Hayden Operations July 11, 2013 Page 20 Anode Furnaces. 

### A review of EPA's RACT/BACT/LAER Clearinghouse (RBLC) revealed that there are no air pollution control devices that have been approved for anode furnace operations. Other S02 controls are notfeasible given the low concentration ofS02 is the gas stream. Given the absence ofany technically feasible 502 

### controls, BART is determinedto be noadditional control. Asarco appreciates the opportunity to provide this explanation of its plans and analyses forthe Hayden Smelterto EPA. Based upon the best available information, the proposed CRP is the best, ifnot the only, effective alternative for S02 emission control from the Hayden Smelter. Adoption ofthe CRP will achieve superior results to those that can be achieved through the BART process. Given thatAsarco wishes to proceed with the CRP as expeditiously as possible, Asarco does not believe that a BART determination is necessary or appropriate. Please contact me at 520-356-3284 ifyou have any questions concerning this response. Sincerely, 

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Jack Garrity Technical Services Manager JG/rcg Attachment

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REnviro/AIRlHayOps/Smelter/OtherCorres/BART/EPARFI6.27.13/AsarcoResponsetoEPAJuneRFI7.11.13