From: To: Cc: History:



### Bill, Cliffs' Response to EPA's Questions on the Regional Haze FIP Comments (October 30, 2012) McWilliams, A. to: William Wagner 11/09/2012 07:01 PM Cc: Steven Rosenthal, "Michael Long (MichaeLLong@CiiffsNR.com)" "McWilliams, Douglas A." <Douglas.McWilliams@squiresanders.com> William Wagner/R5/USEPNUS@EPA, Steven Rosenthai/R5/USEPNUS@EPA, "Michael Long (MichaeLLong@CiiffsNR.com)" <Michaei.Long@CiiffsNR.com> This message has been replied to and forwarded.



### Attached are Cliffs Natural Resources' responses to your clarifying questions submittedby e-mail to me onOctober 30, 2012 pertainingto the cost effectiveness calculations inCliffs' comments onEPA'sproposed Regional Haze Federal ImplementationPlanfor taconite furnaces. The response is inthe form ofa letter from Mike Long withthree referenced attachments providingtechnical support. Please notethatwe include a placeholder for one ofthe vendors because they were not able to respond from theirNewJersey office inthe time allotted due to severe weather challenges. Wewill supplementtheresponse whenthat informationis available.

Please contact mewith questions.
Douglas A. McWilliams Partner douglas.mcwilliams@squiresanders.com T +1 216 479 8332 

### 0 +12164798500 F +1 

### 216 479 8780 M +1216 407 4968 Squire Sanders (US) LLP 4900 Key Tower 127 Public Square Cleveland, Ohio 44114-1304 www.squiresanders.com

### ---------------------------------------------------------------------37 Offices in 18 CountriesThis message is confidential and maybe legallyprivileged or otherwise protectedfrom disclosure. Ifyou are notthe intendedrecipient, pleasetelephone or emailthe sender and deletethis message and any attachmentfrom your system; youmustnot copy or disclose the contents ofthis message or any attachmentto any otherperson.Squire Sanders (US) LLP is part ofthe international legal practice Squire Sanders which operates worldwidethrough a number ofseparate legal entities. Please visitwww.squiresanders.com for more information.#US 

# m -

Cliffs_Response_to_EPA_BART _FIP_Questions 1 0-30-12_.pdf

# m -Attachment 1 Cliffs Response to EPA Quaestions on Regional Haze FIP Comments 10-30-12.pdf

# ll?J -Attachment 2 Cliffs Response to EPA Questions on Regional Haze FIP Comments 10-30-12.pdf

# m -Attachment 3 Cliffs Response to EPAQuestions on Regional Haze FIP Comments_10-30-12.pdf

# ·~CLIFFS CLIFFS NATURAL RESOURCES INC. 1100**Su;J(~rior** Avenue, Suit(1 i500, C1Bve!and, OH**.'l~**114-2.544 P 216 694_5700 F**216.69·~..1880 ct!Jfsna~t;ralrosources.corn**  

### November 9, 2012
VIAELECTRONIC MAIL (wagner.william@epa.gov) William Wagner U.S. EPARegion 5 Office ofRegional Counsel (C-14J) 77 W. Jackson Boulevard Chicago, IL 60604 Re: Response to EPA's Clarifying Questions from October 30,2012 on Cliffs Natural Resources' Comments on theProposed Regional HazeFIP for Taconite Furnaces DearBill: This document responds to your e-mail dated October 30, 2012 to Douglas McWilliams (outside enviromnental counsel) requesting clarifying information relating to the costeffectiveness analysis included in the confidential business information comments submitted by Cliffs Natural Resources on September 28, 2012 regarding U.S. EPA's proposed regional haze federal implementation plan (FIP) for taconite facilities. Each ofEPA's questions is addressed in this letter and the attachments prepared by Barr Engineering in consultation with vendors. One ofthe vendors has its offices in New Jersey and its ability to respond to our request for infonnation has been hampered by Hurricane Sandy and other challenging weather conditions. We will forward additional information from that vendor as itbecomes available We understand that you are requesting this information to confirm whether or not add-on controls for sulfur dioxide are appropriate for one or more ofthe gas streams at Tilden and at United Taconite, the two taconite facilities that use coal in their fuel mix. Cliffs used Barr Engineering to gather information from vendors and engineers to assess whether dry scrubber S02 

### controls were cost-effective for these grate kiln 

### furnaces. We set out to design, in the limited time that we had been allotted, the most efficient and effective S02 

### control system for each facility. We are confident that you will conclude, as we did, that this is an appropriately conservative design that does not add unnecessary costs. EPA also noted that Cliffs calculates a smaller rate ofemission reduction for the add-on S02 

### controls, which affects the cost-effectiveness calculation. As explained in greater detail below, Cliffs started with actual emission rates, as recommended by EPA's Appendix Y BART guidance, instead ofthe allowable emission rates used byEPA. The actual emission reduction is significantly lower than the reduction ofpotential emissions from the permitted emission levels used in EPA's calculation. We are confident that a proper cost-effectiveness evaluation must be based on actual emission reductions.

### William Wagner November 9, 2012 Page2 The specific responses to EPA's questions are described below and explained further in the referenced documents attached to this letter. Informationrequested for Tilden Line I I) EPA requested a "simple schematic diagram showing existing gas flows" associated with the Tilden Line I indurating furnace with a description ofthe three gas streams that vendors recommend to be mixed in a common duct before adding either a Gas Suspension Absorption (GSA) system or spray dry absorber (SDA) for S02 

### control. The schematics are included as Attachment I. 

### The characteristics of the gas streams are in Table 1 to Barr's Technical Memorandum included as Attachment 3. 2) EPA also requested "further explanation regarding the need for parallel absorber modules" for S02 

### control at Tilden Line I. 

### EPA understands that two absorber modules would be necessary to handle the combined gas flow from Tilden Line I, bnt EPA seems interested in evaluating whether a single scrubbing module wonld be cost-effective for handling lowoperation gas flows or an uncombined portion ofthe gas flow. The information EPA requested is included in Barr's Technical Memorandum included as Attachment 3. As explained more completely in that memo, the decision to combine the three gas strean1s reuses energy fromthe furnace to elinlinate the need for additional natural gas-fired dnct burners to sustain temperature and eliminate moisture that would otherwise impede operational efficiency and damage the dry scrubber system. As such, controlling a combined gas stream, as evaluated by Cliffs, minimizes cost ofcontrol, improves reliability and improves efficiency. Informationrequested for UTAC 3) EPA asked for clarification on how Cliffs derived the S02 

### emtsston reductions attributable to the proposed BART FIP controls at United Taconite, which were smaller than those EPA had assumed. The most significant difference is the baseline S02 

### emission rate. As explained in greater detail in Ban's Technical Memorandum (Attachment 2), Cliffs started with actual 2012 S02 

### emissions data as its baseline emission rate while EPA proposed using maximum allowable emissions from a recent permit. EPA's Appendix Y BART guidance at 40 CFR Part 51 directs that we use aetna! emissions from a baseline period to estimate anticipated annual emissions when performing a cost-effectiveness evaluation. Consistent with that guidance, Cliffs used its continuous emission monitor data for S02 

### at United Taconite since the green production project (GPP) was implemented. The CEM data only covered pati ofthe year and did not reflect the facility's production goals for 2013. Therefore, we used the CEM data from Januaryto August of2012 and then multipliedthese actual measured emissions by the ratio of aetna! production to maximum ammal production under the GPP permit. As explained in greater detail in the Attachment 2, this approach yields anticipated baseline emissions of729 tpy for Line I and 910 tpyfor Line 2, in line withthe aetna! emission unit performance anticipated to be realized under the GPP, which are far below EPA's assumed allowable baseline S02 

### emissions of 1,128 tpy and 2,556 tpy respectively.

### William Wagner November 9, 2012 Page 3 As EPA's guidance indicates, the cost-effectiveness ofa control device mustbe evaluated based on actual emission reductions attributable to the device. As such, EPA directs that the BART cost-effectiveness determinations start with a "realistic depiction of anticipated annual emission for the source." See 40 CFRPart 51, Appendix Y.N.D.4.d. The CEM data capture the current and anticipated fuel mix at United Taconite, which includes more low-sulfur natural gas and less high-sulfur solid fuel. When starting with the CEM-based baseline, the 95% emission reduction or the 5 ppm emission rate generate far smaller actual emission reductions attributable to the control device. As demonstrated in our September 281 h 

### comments, the cost per ton of actual S02 

### reduction is far too high to be considered cost-effective retrofit technology for United Taconite. 4) EPA asks for confirmation that parallel scrubbers are necessary at UTAC Line 2 and Tilden Line I, and an explanation for why parallel scrubbers are not needed to maintain gas velocity at UTAC Line I. 

### This information is provided in Barr's Technical Memorandum (Attachment 3). 5) EPA also asks for information regarding the value ofthe additional ore captured by the new ESPs installed for particulate control and iron ore recovery before the dry scrubber S02 control. As explained in greater detail in Attachment 3, the iron ore that would be captured by the ESP is currently captured by the wet scrubber at UTAC. The iron ore is recycled in either configuration so there is no additional value attributableto iron ore capturedbythe ESP. We appreciate the opportunity to help EPA understand our taconite facilities and to clarify our comments on the proposed BART FIP. We wouldbe happy to arrange a conference call, ifthat would be a more efficient way to exchange information to gain an understanding of the cost effectiveness analysis, or any other aspect ofour comments. Sincerely, /Michael Long/ · Michael E. Long

MICHAEl E. lONG Director- Corporate Environmental Regulatory Strategy and Analysis P216.694.7359 (O) 216-262-8797 (M) Michaei.Long@cliffsnr.com 

### CLIFFS NATURAL RESOURCES 1100 Superior Avenue, Suite 1500, Cleveland, 

### OH 44114-2544

### William Wagner November 9, 2012 Page4
Attachments

cc: Douglas A. McWilliams, Squire Sanders (US) 

### LLP StevenRosenthal, U.S. EPA

### Region VFigure 1- UTAC Line 1 11/5/2012Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry502 Controls at UTAC and Tilden

Green Balls Cyclone

Downdraft 

# IDowndraft

Drying 1 Drying 2

Venturi Scrubber Cyclone

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# 1

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·•••••••••• Coal Primary Cooling
;<;;

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Air Finished PelletsFigure 2- UTAC Line 2 11/5/2012Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden

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Downdraft

Drying 2

Venturi Scrubber

Venturi Scrubber Cyclone

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### '--------T+--' To Atmosphere 

# r

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2a To Atmosphere 

# r

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# "

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Air Finished PelletsFigure 3- Tilden Line 1 11/5/2012Technical Memorandum Re EPA Questions onthe 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden

# ~~ ESP**~** To North

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## resourceful. naturally. 

# BARR engineering and environmental consultants

From: Paul Taylor Subject: DerivationofS02 Emission Reductions for United TaconiteLines I and2 Date: November2, 2012
This is inresponse to the following item in EPA's 10/31/2012 e-mail (authored by Bill Wagner) to Cliffs Natural Resources (care ofDoug McWilliams, Squire Sanders LLP): 

### InfOrmation neededtor UTAC
Barr p3 discusses use ofCEMs datafor 2012 proratedfrom current production to the capacity allowed by the greenproductionproject (GPP}. Barrp4 says that the FIP S02 reductions of1,164 tpyforLine 1 and2,475 tpyfor Line 2 are incorrect andshould be 650 tpy and 760 tpy, respectively. The GPP S02permit limits are 1128 tpyfor Line 1 and2556tpy for Line 2. (Are these still correct?) A 95% reductionfrom these limits would be 1,072 tpyfor line 1 and 2,428 tpyfor Line 2. Please explain how the lower emission reduction estimates werederived.
The "Barr" docmnent that EPA is referring to is Barr's teclmical me1norandmn titled '"United Taconite 802 Control Cost Analysis" which was submitted as Attachment BB to Cliffs Natmal Resources' 9/28/2012 comments on the proposed Regional Haze Federal Implementation Plan, 77 Fed. Reg. 49308 (Aug. 15, 2012) ("Proposed Rule").
BatT page 3 states:


### In all cases listed in Table 1 and2, the S02 baseline emissions are basedon S02 continuous emission monitoring system (CEMS) data for 2012 proratedfrom current production levels to the full production capacity of the Green Production Project (GPP)permit 1 

### established inAugust, 2010. The 2006 BARTbaseline did not include emissionsfrom coal combustion on Lines 1 and2 and are not representative of expected actualS02 emission rates basedon CEMS data. The S02 emiSsion control cost calculations use theperformance specified by theproposed FIP limit of 5ppm S02

### for CFBA scrubbers and the control equipment suppliers'performance guarantee (> 

### 90% removal)for SDA scrubbers to calculate the assumedcontrolledemissions.

Barr Engineering Co. 332 West Superior Street, Suite 600, Duluth, MN 55802 218.529.8200 www.barr.comFrom: Paul Taylor Subject: Derivation of S02 Emission Reductions Projected in Cliffs' Comments on the Proposed Regional Haze FIP Date: November J. 2012 Page: 2

1 

### The GPP permit limits Line 1 S02 

### emissions to 1,293 tons/year and Line 2 emissions to 2,394 tons/year. 

### Table I on Page 3 lists the Line I "Annual S02 

### Emission Reduction as 650 tons/yr for the Circulating FluidBed analyzer and 660 tons/yrfor the Spray DryAbsorber. Table 2 on Page 4 lists the Line 2 "Annual S02 Emission Reduction as 760 tons/yr for the Circulating Fluid Bed analyzer and 820 tons/yr for the Spray DryAbsorber. Page 4 states: The S02 

### emission reduction of1,164 and 2,475 tonsper year, for Line 1 and Line 2 respectively, listed in Table V-B.ll ofthe proposed FIP did not accurately consider the anticipated annual emissions 1 

### under the GPP. For CFBA at controlledS02 

### concentration of 5ppm, the calculatedS02 

### reduction is 650 tonsperyear for Line 1 and 760 tonsperyear for Line 2. At the baseline emission rate andtheproposedFIP limit of a 95% S02 

### controlefficiency, S02 

### concentrations atthe outletof a dry FGD on United Taconite Lines 1 and 2 would be below the CFBA supplier performance guarantee and theproposedFIP limit of 5ppm. The S02 

### emission reductionfor SDA was calculated at a 90% control efficiency. The SDA equipment supplierproposed aperformance guarantee of> 90% S02 

### control. Based on thisperformance guarantee, it 

### is uncertain whether or not theproposed FIP limit of 5ppm S02 

### couldbe metwith a SDA scrubber.

1 

### The cost effectiveness guidance refers to use of "a realistic depiction ofanticipated annual emissionsfor the source . ..for the existing sources subject to BART, you will estimate the anticipated annual emissions based upon actual emissionsfrom a baselineperiod." 40 CFR Part51, App. Y.4.d. 

### (sic, should be 40 CFRPart 51, App. Y.IV.D.4.d) Responses toEPA's 10/31112 e-mail:
I. 

### EPA's e-mail states that "The GPPS02permit limits are 1128 tpy forLine 1 and2556tpy forLine 2" 

### and asks whetherthese limits are still correct. In fact, the GPP S02 

### permit limits are I,293 tons/yr for Line I and 2,394 tons/y:r for Line 2. These are specifiedon pages A-49 and A-56, respectively, of United Taconite's Title V airpermit 13700113-005, issued 8/19/2010 (copies attached). 2. EPA's e-mail asks Cliffs to explainhowthe lower S02 

### emission reduction estimates for CFBA (650 tons/yr for Line 1 and 760 tons/yr for Line 2) were derived. The emissionreductions wereFrom: Subject: Date: Page: Paul Taylor Derivation of S02 Emission Reductions Projected in Cliffs' Comments on the Proposed Regional Haze FIP November l, 2012 3 

### estimated in accordance with 40 CFR 51, Appendix Y ("Guidelines for BART Determinations Under the Regional Haze Rule"), IV.D.4.c, as the difference betweenthe "baseline annual emissions" and the "annual emissions with control option". According to 40 CFR Part 51, App, Y.IV.DA.d.l, "The baseline emissions rate shouldrepresenta realistic depiction of anticipatedannual emissionsfor the source. In general,for the existingsources subject to BART, you willestimate the anticipatedannual emissions basedupon actual emissions from a baselineperiod" The S02 

### CEMS installed on each indurating furnace stackprovide the best available data for estimating actual emissions from a baseline period. A baseline period from 111/2012 through 8/31/2012 was selectedbecause this period is believedto be representative ofhow United Taconite (i) has operatedthe furnaces sincethe implementationofthe GreenProduction Project ("GPP", the subject ofpermit 13700113-005), and (ii) anticipates operating the furnaces inthe future. The actual emissions for this eightmonthperiod (i.e., the sum ofvalidhourly "lb/hr" CEMS values) were scaled up to ananuual basis using the ratio ofthe allowable (annual) to actual (eight month) production levels.
The "anuual emissions with control option" were calculated assuming the proposedBART FJP limit of5 ppm S02• 

### Based onthe method described above, the S02 

### emissions reductions were derivedfor each indurating furnace line as follows:
Line 1:
Baseline annual emissions: 2012 actual emissions (357 tons for the period 1/1112-8/31/12 according to CEMS data) 

### I2012 actual production level (955,742 LT pellets for the period 1/1112-8/31/12) x the GPP allowable production level (1,950,000 L Tpellets/yr assumed in the GPP permitapplication)**~** 

### 729 tons/yr.
Annual emissions with

### control option: 5 ppm S02 I 

### !,000,000 ppmx 358,758 sdiminx 64.1 lb/lb-mol x 60 min/hr I 

### 385 c£1lb-mol x 8,760 hrs/yr I 

### 2,000 lb/ton**~** 

### 78 tons/yr. Notethatthe air flow rate is based onthe average of 13 stacktests performed on SV 046 since May 2006.From: Paul Taylor Subject: Derivation of S02 Emission Reductions Projected in Cliffs' Comments on the Proposed Regional Haze FIP Date: November 1, 2012 Page: 4 Projected S02 emissionreductions: Baseline annual emissions (729 tons/yr)- Annual emissions withcontrol option (78 tons/yr)**~** 651 tons/yr, rounded to 650 tons/yr. Note thatapplying the alternative proposed FIP limit ofa 95% S02 control efficiency to the baseline annual emissions (729 tons/yr) gives a controlled S02 emissionrate (729 x (1-95%)**~** 36tons/yr) that is belowthe CFBA supplier performaoce guarantee andthe proposed F1P limit of5 ppm(equivalent to 78 tons/yr as shown above)
Line 2:
Baseline annual emissions:
2012 actual emissions (556 tons for the period 1/1/12-8/31/12 according to CEMS data) /2012 actual production level (2,476,234 L T pellets for the period 1/1/12-8/31/12) x the GPP allowable production level (4,050,000 L T pellets/yr assumed in the GPP permit**application)~** 910 tons/yr.
Annual emissions with control option: 5 ppm S02 /1,000,000 ppmx 700,135 scf/minx 64.1 lb/lb-mol x 60 min/hr/385 c£11b-mol x 8,760 hrs/yr 

### I 2,000 lb/ton**~** 153 tons/yr. Note thatthe air flow rate is based onthe average of35 stacktests performed on SV 048 aod 20 stack tests performed on SV 049 since May 2006. Projected S02 emission reductions: Baseline annual emissions (910 tons/yr) -Annual emissions with control option (153 tons/y:r)**~** 757 tons/yr, rounded to 760 tons/yr. Note that applying the alternative proposed FIP limitofa 95% S02 control efficiency to the baseline aooual emissions (910 tons/y:r) gives a controlled S02 emissionrate (910 x (1-95%)**~** 46 tons/yr) that is belowthe CFBA supplierperformance guarantee and the proposedFIP limit of5 ppm (equivalent to 153 tons/yr as shown above)TABLE A: LIMITS AND OTHER REQUIREMENTS Facility Name: United Taconite LLC- Fairlane Plant Pennit Number: 13700113-005 Subject Item: EU 040 Line 1 Pellet Induration Associated Items: CE 056 Wet Scrubber-High Efficiencyw/o Lime MR 001 NOx monitor MR 002 S02 monitor MR 003 Flow monitor

POLLUTANT LIMITS SV046 SV097 Whatto do Opacity: less-than or equal to 20 percent opacity exceptfor one six-minute period per hour ofnot more than 60 percent opacity. Total Particulate Matter: less than 0.3 grains/dry standard cubicfoot ofexhaust gas unless required to further reduce emissions to comply with the less stringent of either Minn. R. 7011.0730 or Minn. R. 7011.0735. Total Particulate Matter: less than or equal to 0.0070 grains/dry standard cubic foot using 3-hour Average (standard cubic feet ofexhaust gas) The Permittee shall operate and maintain the control equipment such that it achieves an overall control efficiency for Total Particulate Matter: greaterthan or equal to 94 percent control efficiency PM < 10 micron: less than or equal to 0.0139 grains/dry standard cubic foot using 3-hourAverage (standard cubic feet ofexhaust gas) The Permittee shall operate and maintain the control equipment such that it achieves an overall control efficiency for PM < 10 micron: greaterthan or equal to 84 percent control efficiency PM< 2.5 micron: less than or equal to 0.0139 grains/dry standard cubic foot using 3-hourAverage (standard cubic feet ofexhaust gas) The Permittee shall operate and maintain the control equipment such that it achieves an overall control efficiency for PM < 2.5 nlicron: greaterthan orequal to 84 percent control efficiency Sulfur Dioxide: less than or equal to 4 lbsfmillion Btu heat input using 3-hour Average when only asolid fossil fuel is burned. If more than one fuel is burned simultaneously, calculate the emission limit as indicated in Minn. R. 7011.0605. Sulfur Dioxide: less than or equal to 2 lbs/million Btu heat input using 3-hour Average when only a liquid fossil fuel is burned. lf more than one fuel is burned simultaneously, calculate the emission limit as indicated in Minn. R. 7011.0605. Sulfur Dioxide: less than or equal to 106.3 tons using 30-day Rolling Sum rolled daily. This condition restricts 802 emissionsfrOm EU 040 to 1293tons per year. Nitrogen Oxides: less than or equal to 816 tons using 180-day Rolling Sum rolled daily. This conditions restricts NOx emissions from EU 040 to 1655 tons per year. SulfuricAcid Mist: tess than or equal to 6.25 tons using 30-day Rolling Sum rolled daily. This restricts Sulfuric Acid Mist emissions from EU 040 to 76.1 tons oer vear. Operating Hours: less than or equal to 7992 hoursfyear using 365-day Rolling Sum calculated daily OPERATIONAL REQUIREMENTS Authorization to commence construction on the modification of EU 040 authorized by Air Emission Permit No. 13700113-005 expires on June 24,2010. A-49 08/19/10

Whv to do it hdr Minn. R. 7011.0610, subp. 1(A)(2) Minn. R. 7011.0610, subp.1 (A)(1) and Minn. R. 7011.0710, subp. 3 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title 1Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title 1Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Minn. R. 7011.0610, subp. 2(8)

Minn. R. 7011.0610, subp. 2(8)

Title I Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R 7007.3000 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000 Title 1Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R 7007.3000 Title I Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R. 7007.3000 hdr Title 1Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R. 7007.3000TABLE A: LIMITS AND OTHER REQUIREMENTS Facility Name: United Taconite LLC**~** Fairlane Plant Pennit Number: 13700113-005 Subject Item: EU 042 Line 2 Pellet Induration Associated Items: CE 049 Wet Scrubber-High Efficiencyw/o Lime CE 050 Wet Scrubber-High Efficiency w/o Lime MR 004 NOx monitor

POLLUTANT LIMITS MR 005 S02 monitor MR 006 Flow monitor MR 007 NOx monitor MR 008 S02 monitor MR 009 Flow monitor SV048 SV049 SV098 What to do Opacity: Jess than or equal to 20 percent opacity exceptfor one six-minute period oer hour ofnot more than 60 oercent ooacitv. Total Particulate Matter: less than or equal to 0.0157 grains/dry standard cubicfoot using 3-hourAverage (standard cubicfeet ofexhaust gas). Compliance with this limit also demonstrates compliance with Minn. R. 7011.0610, subo.1!Alt1) and Minn. R. 7011.0715, subo.**1~(A).** The Pennittee shall operate and maintain the control equipment such that it achieves an overall control efficiency forTotal Particulate Matter: greater than or**~~al** to 94 percent control efficiencV PM < 10 micron: less than or equal to 0.0189 grains/dry standard cubicfoot using 3-hourAverage (standard cubic feet ofexhaust gas) The Pennittee shall operate and maintain the control equipment such that it achieves an overall control efficiency for PM< 10 micron: greater than or equal to 84__R_ercent control efficiency PM < 2.5 micron: less than or equal to 0.0189 grains/dry standard cubic foot using 3-hourAverage (standard cubicteet ofexhaust gas) The Penn'ittee shall operate and maintain the control equipment such that it achieves an overall control efficiency for PM < 2.5 micron: greater than or equal to 84 oercent control efficiency Sulfur Dioxide: less than orequal to 4 lbs/million Btu heat input using 3-hour Averagewhen only a solid fossil fuel is burned. Ifmore than one fuel is burned simultaneously, calculate the emission limit as indicated in Minn. R. 7011.0605. Sulfur Dioxide: less than orequal to 2 lbs/million Btu heat input using 3-hour Average when only a liquid fossil fuel is burned. If more than one fuel is burned simultaneously, calculate the emission limit as indicated in Minn

..R. 7011.0605. Sulfur Dioxide: less than or equal to 197tons using 30-day Rolling Sum rolled daily. This condition restri'cts S02 emissionsfrom EU 042 to 2394 tons per year. Nitrogen Oxides: less than or equal to 1820tons using 180-day Rolling Sum rolled daily. This condition restricts NOx emissions from EU 042 to 3692 tons per year. . SulfuricAcid Mist: Jess than or equal to 15.4tons using 30-day Rolling Sum rolled daily. This condition restricts SulfuricAcid Mist emissions from EU 042 to 186.8 tons per year. Operating Hours: Jess than or equal to 7992 hours/year using 365-day Rolling Sum calculated daily A-56 08/19/10

Why to do it hdr Minn. R. 7011.0610, subp. 1(A)(2) Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7011.0610, subp.1(A)(1) and Minn. R. 7011.0715, subp.1(A); Minn. R. 7007.0800, subos. 2 and 14 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I CondiUon: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Title I Cond'ition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000; Minn. R. 7007.0800, subps. 2 and 14 Minn. R. 7011.0610, subp. 2(8)

Minn. R. 7011.0610, subp. 2(8)

Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000 Title I Condition: To avoid classification as a major modification under40 CFR Section 52.21 and Minn. R. 7007.3000 Title I Condition: To avoid classification as a major modification under 40 CFR Section 52.21 and Minn. R. 7007.3000

Title I Condition: To avoid classification as a major modification Linder40 CFR Section 52.21 and Minn. R. 7007.3000

## resourceful. naturally. 

# BARR engineering and environmental consultants

From: Jack Kennedy Subject: EPA Questions onthe S02 Control CostAnalysis for Dry S02 Controls onUnitedTaconite Lines I and 2 andTildenLine I Date: November 9, 2012 This technicalmemorandum is in response to the items in italicfont listed belowwhich were contained in EPA"s 10/31/2012 e-mail (authored by Bill Wagner) to Cliffs Natural Resources (care of Doug McWilliams, Squire Sanders (US) LLP). The designs for application of dry S02 (sulfur dioxide) control systems and the associated ancillary equipment requirements for installation ofdry S02 controls at United Taconite (UTAC) and Tilden are highly dependent upon the design ofeach induration fumace. There are significant differences between the UTAC and Tilden induration furnaces which must be understood in order to understand the responses to the questions posed by United States Environmental Protection Agency (EPA) in its 10/31/2012 email to counsel for Cliffs Natural Resources. To assist with understanding ofthe induration furnace processes and to adequately respond to the questions posed by EPA, descriptions ofinduration furnace traveling grate sections for induration furnaces at UTAC and Tilden are provided. In addition, simplified flow diagrams for each furnace are included as attachments to the memorandum. The memorandum is organized as follows:

• A general description ofgrate/kiln indurationfurnaces
• A brief description of UTAC Line 1 and 2 traveling grate sections and how the grate design affects operation ofthe induration furnaces and characteristics ofthe exhaust streams.
• Responses to EPA questions regarding UTAC Lines I and 2.
• A briefdescription ofTilden Line I traveling grate section andthe implications ofits design.
• Responses to EPA questions regarding Tilden Line I.

Borr Engineer!ng Co. .:1700 We$177!h Srreet, Suite 200, Minneapolis, MN 55435 952.832.2600 www.borr.cotnFrom: Jack Kennedy Subject: EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1and 2 and Tilden Line 1 Date: November9, 2012 Page: 2 

### General Grate/Kiln Induration FurnaceDescriptions The Tilden and UTAC induration furnaces are grate/kilntype furnaces. Feed (green balls) to a grate/kiln furnace is introducedto a moving grate at the front end ofthe furnace for drying andpre-heating. Pellets proceed from the moving grate into a rotary kiln where they are hardened. After exiting the kiln, the hardened pellets pass through a pellet cooler which uses ambient air as the cooling medium. Finished pellets are discharged fi·om the outletofthe pelletcooler.
In order to minimize the fuel requirements ofthe rotary kiln, the grate portion ofthe induration furnace is designed with recuperative heat recovery systems which utilize the hot exhaust from the rotary kiln and pellet cooler to dry and preheatthe green ball pellets. The inside ofthe moving grate enclosure contains baffles which are used to direct the flow ofhot gases through the pellet bed on the moving grate. These baffles are organized into sections where kiln and/or pellet cooler exhaust is directed for heatrecovery. It 

### is the differences in the design ofgrate sections in the Tilden and UTAC induration furnaces which determine the number of induration furnace exhaust streams and the composition, moisture content, temperature and S02 

### concentration ofeach exhaust stream. Most ofthe water in the green balls is driven offin the first sections ofthe traveling grate. Gases released from this section have the highest moisture content and the lowest temperature. S02 

### is released fi·om the green ball pellets in both the higher temperature sections ofthe traveling grate and kiln sections ofa grate/kiln induration furnace. S02 

### fi·om fuel combustion is released in the rotary kiln and is exhausted through the grate sections which receive hot gases from the kiln. So 802 

### willbe present in all induration fumace exhaust streams. Simplified flow diagnuns ofeach induration furnace are attached to this memorandum. Figures I and 2 are diagrams of UTAC Lines I and 2 respectively. Figure 3 is a diagram ofTilden Line 1. In the following sections of this technical memorandum, there is a description ofthe grate sections for each induration furnace. This is followed bythe questions raised by EPA regarding the dry S02 

### control system design used for the S02 

### control cost analysis andthe response to each question.
Process Descriptions United Taconite Lines t and 2 

### Both UTAC Line! and Line 2 have traveling grates which are divided into three sections: Downdraft Drying I; Downdraft Drying 2; and Preheat. The preheat section is the hottest. It is heated by kiln exhaustwhich flows directly into the preheat section. After exitingthe preheat section, the kiln exhaust is directed via ductwork to Downdraft Drying I for further heat recovery. The hot exhaust from the pelletFrom: Jack Kennedy Subject: EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1and 2 and Tilden Line 1 Date: November9, 2012 Page: 3 cooler is directed via ductwork to DowndraftDrying 2. BothDowndraftDrying I and Downdraft Drying 2 exit the induration furnace through a common duct into a venturi scrubber system for particulate removal. The venturi scrubber systems prevent abrasive iron dust from reaching the procesS exhaust fans and damagingthem.
UTAC Line I has a single exhaust gas system with one exhaust gas fan and one stack. All exhaust gases exitingthe induration furnace areroutedthroughthis scrubber system, process exhaustfan and stack.
UTAC Line 2 production rate and physical size is twice that ofLine I, which requires the gas flow rate throughLine 2 to be approximately twice that ofLine 1. To accommodate the higher gas flow rate, Line 2 was designed with two exhaust gas ducts, two venturi scrubber systems, two process exhaust gas fans and two stacks. One exhaust gas system is located onthe north side ofLine 2 and the other is located on the south side. The systems are mirror images ofone another. The Line 2 exhaust gas systems are both the same size and have essentiallythe same gas compositions. All three exhaust gas fans have approximatelythe same designflow capacity. Response to EPA questions onUTAC Lines 1 and 2 The EPA questions provided in the October 

### 31,2012 email ofthe UTAC Line 1 and 

### 2 dry scrubber system designbasis are listed below followed by a response. Barrpp 8&9 say thatLine I has oneprocess blower andLine 2 has twoprocess blowers, andLine 2 can operate on oneprocess blower. Barr argues that two FGDs are necessarv tor Line 2 to maintain gas velocity. !(thatwere true, Line I wouldalso needparallel halt:sizedFGDsfOr lowflow conditions, which Barr has notprooosed. Please provide statements from vour vendors to confirm that parallel scrubbers
are necessary at UTAC Line 2 and Tilden Line I, and explain why parallel scrubbers are not needed to maintain gas velocitv at UTAC Line I. Dry scrubbers .are used on utility and industrial boilers, and we are notaware of a need forparallelscrubbers to handle turn-down conditions at these boilers. Response- Parallel Scrubberson UT AC Line 2 The total exhaust gas flow rate from UTAC Line 2 pushes the limits of the maximum design flow capacity ofthe Ducon and FL Smidth dry scrubbers proposed for this application to achieve the level of S02 control as specified in the draft federal implementation plan (FIP) by EPA. Therefore, two parallelFrom: Jack Kennedy Subject: EPA Questions on theS02 Control Cost Analysis for Dry S02Controls on United Taconite Lines 1 and 2 and Tilden Line 1 Date: November 9, 2012 Page: 4 

### dry scrubbers were recommended by the vendors to meet the needs for this application, to accommodate the full exhaust gas flow rate Jiom Line 2, and to meetthe S02 

### control performance levels specified inthe draft FIP. The combined exhaust gas flow rate from UTAC Line 2 used in the S02 

### control cost analysis is 1,128,000 acfin (805,000 scfm).

• The maximum flow capacity for the Ducon dry scrubbers will be forthcoming once received from Ducon. Ducon's facilities have been affected by the recent stmms along the East Coast and have notrecovered power. 

### • Per FL Smidth email dated 1111/2012, maximum flow capacity for FL Smidth dry scrubbers currently is 401,000 scfin (635,000 Nm3/hr). Statements from eachvendor are locatedinAttachments I and2 to thememorandum. Response- Dry ScrubberTurndown Rates on UTAC Line 1 vs. Line 2 As noted in the vendor responses in Attachments I and 2, dry S02 

### scrubbers have a turndown rate of approximately 50%. At flow rates below 50% ofcapacity, gas flow rates in illy S02 

### scrubbers are not high enoughto keep the spent reagent in suspensionfor transport from the absorber into the baghouse for collection. In a circulating fluidized bed absorber gas flow rates below 50% of capacity are not sufficientlyhighto keep reagent suspended in the fluidized bed absorber. Ifthe UTAC Line I process exhaust fan fails or is shut down for maintenance, Line I must shut down. Therefore, the turndown requirements do not exist for Line I. 

### They would potentially only exist for UTAC Line 2, as discussed below.
For the purpose ofestimating S02 

### control costs, Cliffs Natural Resources has assumedthat with only one fixed speed exhaustgas fan a dry S02 

### scrubber turndownrate of50% is sufficient. This results in a lower S02

### control costthan installation oftwo small dty scrubbers to accommodate a productionrate below 50% ofcapacity. UTAC Line 2 cunently has two fixed speedprocess exhaust gas fans and can operate in a reduced productionmode with only one process exhaust fan operating. This flexibility in operation is required to meetproduction needs. When operatingwith only one process exhaust gas fan in service, exhaust gas flowrates are reduced to 50% ofcapacity or less and still maintain the process parameter integrity. Ifa single dry 

### SO, scrubber was used, as proposed by EPA, instead ofthe two scrubber system asFrom: Jack Kennedy Subject: EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1 and 2 and Tilden Line 1 Date: November 9, 2012 Page: 5 recommended by the vendor, the exhaust gas flow rate in the single fan operating mode wouldbe at or belowthe minimum flow rate allowable for a dry S02 scrubber (50% tumdown). By installing two d1y scrubbers onLine 2, either exhaustgas dry S02 scrubber can safely operate withinits designrange when Line 2 is operating in single fan mode.


### BarrplOsays thatnew dry ESPs will be installed forparticulate controlandiron ore recovery. B) What is the value o(theadditional ore capturedby the ESPs v. the wetscrubbers Response- AdditionalIron OreRecovery from a dry ESP:
No additional iron ore will be recovered ifa d1y ESP is installedto accommodate installation ofa dry S02 scrubber. Ifd1y ESPs were installed for this purpose, they would recover the same amount ofiron ore dust as the existing venturi scrubbers. The primary purpose ofboth particulate removal systems is to protect the process exhaust gas fan from damage by abrasive iron or dust particles. Ifa dry ESP were installed as part ofa dry S02 scrubbing system, it would be designed to meet the same exhaust gas dust 

### concentration specifications as the existing venturi scrubbers. The currentwet scrubbing systems remove a sufficient amount ofiron ore dust toprotectthe existiog exhaustgas fans. The reason dry ESPs were included as ancillary equipment in the dry S02 scrubber control cost analysis for UTAC is that a dry S02 scrubber will not work downstream of a wet particulate scrubber. Gases entering a dry S02 scrubber must be hot enough and have a low enough moisture content that all the water inthe lime/water slurry injected into the absorber will evaporate. This allows capture ofthe spent lime as a dry powder into the baghouse collection system. The exhaust gas from a wet particulate scrubber is saturated with water vapor and is too cold to absorb all the water present in the lime/water slurry. Ifa dry S02 absorber were installed downstream ofwetparticulate scrubber, the spent lime would not dry in the absorber; instead, it wouldbe wet and not suitable for collection in a baghouse. Consideration of the impact of placing the dry scrubber system upstream of particulate controls was evaluated. Because the wet scrubber is nsed to protectthe exhaust gas fan, installation ofdry S02 controls up stream of a wet scrubber would require that the exhaust fan overcome the total pressure drop associated with the dry S02 control system and the wet scrubber. This would reduce the ability of operators to control the induration fumace operating pressure and air ±low balances by introducing the variability in operating pressure caused bythe dry S02 scrubber into the system. It would also reduce the operating pressure of the induration fumace causing more air infiltration thus reducing the thermalFrom: Jack Kennedy Subject: EPA Questions on the SOz Control Cost Analysis for DryS02 Controls on United Taconite Lines 1and 2 and Tilden Line 1 Dote: November9, 2012 Page: 6 

### efficiency ofthe furnace. There is also the potential for the iron ore dust causing adverse reactions inthe dry scrubber; thus reducing the efficiency ofthe dry scrubber. This infOrmation is necessarv to confirm whether or not a GSA or SDA is apvropriate tOr one or more of UTAC"s three gas streams. Response- The Appropriateness of GSA or SDA for one or more ofUTAC's Three Exhaust Gas Streams: 

### As noted above, UTAC's Line I and Line 2 have similar recuperative heat recovery system designs for the traveling grate sections ofthe grate/kiln induration furnaces. All exhaust gas streams are a mixture of kiln exhaust, pellet cooler exhaust and any 

## so2 released from the green ball pellets during the induration process. The Line 2 exhaust gas systems (north and south exhaust streams) are mirror images ofone another, and both strearos are ve1y similar in nature and are expected to have similar S02 concentrations. Therefore, we did not anticipate any benefit in the cost-effectiveness analysis to consideringthe control of one ofthe exhaust gas systems with a single scrubber module.
ProcessDescription Tilden Line 1 

### The Tilden LineI traveling grate is divided into four sections: Updraft Drying; Downdraft Drying I; Downdraft Drying 2; and Preheat. The Preheat section is the hottest. It 

### is heated by kiln exhaust which flows directly into the Preheat section. After exiting the Preheat section, the kiln exhaust is directed via ductwork to Downdraft Drying 1 

### and Updraft Drying for further heat recovery. There are two parallel duct systems for the transfer ofexhaust gas from Preheat to Updraft Drying and Downdraft Drying I. 

### Dampers regulate the relative amounts ofPreheat exhaust gas which flows to Downdraft Drying I and Updraft Drying. The hot exhaust from the pellet cooler is directed via ductwork to Downdraft Drying 2. Tilden Line 1 

### is designed with a separate exhaust gas duct and blower systems for Updraft Drying, Downdraft Drying I and Downdraft Drying 2. Each exhaust system has a dry ESP for particulate removal to protect the process exhaust gas fans. The Updraft Drying and Downdraft Drying I systems are located on the south side ofTilden Line I and are routed to the South Stack. Downdraft 2 is located onthe north side ofLine I and is vented through the North Stack.From: Jack Kennedy Subject: EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1 and 2 and Tilden Line 1 Date: November 9, 2012 Page: 7 Response to EPA questions on Tilden Line 1
EPA questions fromthe October 31, 2012 email onthe TildenLine I dry scrubber system design basis
are listed below followed by aresponse. We are pleased that Cliffs has re-evaluated the cost-effectiveness ofapplying either

### a Gas Suspension Absorption (GSA) system orspraydryabsorber(SDA) to the combined exhauststreams from the Line 1 indurating furnace atyour Tilden facility. We note that the estimated total capital investment cost for applying these dry-scrubbing options has decreased from $167million in 2006 to $63 million now. We understand that twoparallel GSA!SDA modules wouldbe required to treat the entire combinedgas stream as "gas streams from the lines 2C (from the North Stack) andlines 2A and28 (from the South Stack) will be mixedin 

### a common duct." We also understandthat there are significant differences among the volumetric flow rates andothercharacteristics ofthe three gas streams (which apparentlyprompted Ducon's recommendation that all three exhauststreams be combined). Please provide 

### a simple schematic diagram showing existing gas flows associated with the Line 1 indurating furnace anddescribe the characteristics ofthe three gas stream lsimilarto Table 2 ofBarrEngineering's 9!28/12 report). Response- RequestforTilden Line 1 Simplified Flow Diagram and Exhaust Stream Data Table: Figure 3, a simplified flow diagram ofTildenLine I, is attached to this report perEPA's 10/31/2012 request. In addition, the previous section ofthis reportincludes a process description ofTildenLine I. Table 1, a summary ofTildenLine I exhaust stream parameters, is attached to this report perEPA's 10/31/2012 request. Information inthis table isbased onthe same Cliffs NaturalResources data1 thatthe control equipment suppliers used for the dry S02 scrubber equipment costestimates whichBarrused for the S02 control cost analysis. Please note thatthe TildenLine I South Stack contains the exhaust gas fromthe Updraft Drying and DowndraftDrying I traveling grate zones. Ofthe three exhaust streams, the two exhaust streams vented to the South Stackhave the highestmoisture content and the lowesttemperature. Ducon expressed
concerns that based onthe South Stacktemperature and moisture content; the water dew point approach temperature 2 wouldbe too low for dry S02 scrubbing. DowndraftDrying2 exhaust (North Stack)

1 Tilden Pellet Plant Unit 1 Process Airflow Survey, June 14, 2012. 2 The dew point approach temperature is the difference betweentheoffgas temperature atthe inlet ofthe dry scrubber and thewater dew point oftheoffgas exitingthe scrubber. In a dry502 scrubber, a lime/water slurry isFrom: Subject: Date: Page: Jack Kennedy EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1and 2 and Tilden Line 1 November9, 2012 8 contains sufficientheatto address this concern. So, all three TildenLine I exhaust streams were combined priorto entering the dry S02 scrubbing systemto ensure the inletto tbe dry S02 scrubbing systemwould be maintained atthe proper approach temperature undernonnal operating conditions to allow proper operation oftbe scrubbing system. The alternative to this approach wouldbe to continuously operate a ductburner andburnnatural gas to reheattbe South Stackexhaustto the required temperature. We would also appreciate furtherexplanation regarding the need forparallelabsorbermodules even though one maybe sufficient to handle 

### a gas stream (such as the gas stream with the highest

### SO, concentration) at fullproduction conditions. While we understand that two absorbermodules wouldbe necessary to handle the combinedgas flow from Tilden Line 1, if

### a smallergas flowis treatedthat is within the capacitv of

### a single scrubbing module, would

### a secondmodule stillbe needed to handle lowoperation gas flows? Forexample, we note that the proposal for UTAC Line 1 contains onlyone scrubber module to treat 436,000 acfm. To help us evaluate this issue please provide statements from the scrubbervendors explaining howmuch gas flows to the scrubbers can be "fumed down" andstillbe effective. We also request thatthis vendorinformation be compared to tvoical tum-down ratios for Tilden Line 1. Response- Requestforthe Basis ofthe Design Requirements for Parallel Dry S02 Scrubbers on Tilden Line 1: Statements from each vendor regarding tbeturndown capacity oftheir dry S02 scrubbers are located in Attachments 1and2 to the memorandum.
The combined exhaust gas flow rate from Tilden Line 1used inthe S02 control cost analysis is 1,195,000 acfm (788,000 scfin).

• The maximum flow capacity for the Ducon d1y scrubbers will be forthcoming once received from Ducon. Ducon's facilities have been affectedby the recent storms along the East Coast andhave not recovered power.

injected for 502 control. As water from the lime/waterslurry evaporates in the absorber vessel the offgas temperature drops. Ducon recommends a 500 Fapproach temperature to ensure that the lime/water slurry will be completely dry atthe scrubber outlet and suitable for collection in a baghouse. Ifthe scrubber inletgas temperatureis not hot enough, the spentlime particles will not be completely dry and will foul thedry absorber vessel, ducts, baghouse filters and baghouse hoppers.From: Jack Kennedy Subject: EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1 and 2 and Tilden Line 1 Date: November 9, 2012 Page: 9

• Per FL Smidth email dated 11/112012, maximumflow capacity for FL Smidth dry scrubbers currently is 401,000 scfm (635,000 Nm3/hr). Information from Tilden indicates that flow through the North Stack is 424,000 acftn (275,000 scftn) and flow throughthe South Stack is 771,000 acfm (513,000 scfin). Iftreatment were limitedto the South Stack,two parallel scrubbers wouldbe required to address the volume ofexhaustto betreated. If treatmentwere limitedto the North Stack, one scrubber wouldbe required. Please note thatthis does not take into consideration additional gas flows associated withreheating the exhaust gas to meetminimum operatingtemperature requirements ofa dry S02 scrubber. TildenLine I cannotbe operatedwithonly one process exhaust fan in service. Therefore, turndown capacity was not a factor in selection ofparallel dry S02 scrubbers for this application.
Treatment ofindividual exhaust streams from TildenLine I was notconsidered due to the low South Stack exhausttemperature as discussed above.
This information 

### is necessaryto confirm whetherornot

### a GSA orSOA 

### is appropriate forone ormore of Tilden's three gas streams.From: Subject: Date: Page: Jack Kennedy EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1and 2 and Tilden Line 1 November 9, 2012 10 

### Response- The Appropriateness of GSA or SDA for one or more ofTilden's Three Exhaust Gas Streams: 

### As noted inthe S02 

### control cost analysis (AttachmentL) submittedwith CliffsNatural Resources' September28, 2012 comments to the draft FIP3

, 

### there are limited options for routing ductwork from TildenLine 1to a location where a dry S02 

### scrubber system(s) could be installed. There is insufficient space withinthe induration fumace building to route ductwork from the individualtraveling grate sections onLine 1to the available plot space for dry 

### S02 

### scrubbing onthe south side ofthe building. That is why the proposed system is based ontie-ins to theNorth and South Stacks with a single ductrouted across the top ofthe indurationfurnace building. As noted above, additional heat is needed to maintain the approach temperature ofthe South Stack, and combining the South Stack withthe North Stack exhaustwas used for this purpose inthe S02 

### control cost analysis. Treating only the South Stack would require installation and operation of a re-heat system whichwouldconsume additional natural gas and increase NOx and greenhouse gas emissions.

3 

### Comments ofCliffs Natural Resources on Docket ID Nos. EPA-R05-0AR-2010-0954 and EPA-R05-0AR-2010- 0037, Proposed Approval and Promulgation ofImplementation Plans; States ofMinnesota and Michigan; Regional Haze Federal Implementation Plan, 77 Fed. Reg. 49308 (Aug. 15, 2012) ("Proposed Rule")

### Table 1. 

### Stream Characteristics for Tilden Line 1Exhaust Gas Streams Parameter Value Units Stream UpdraftDrying Downdraft South Stack Downdraft Total Flow Drying 1 (UD +DD1) Drying 2 (North Stack) Inlet Gas Flow 363,000 408,000 771,000 424,000 1,195,000 acfm Inlet Gas SO, 1153 tons peryear Gas Temperature 249 353 301 320 307 degrees F InletPM from ESP 0.03 gr/dscf MWw 29 lb/p-mol Vol% Water 13.5 10.7 12.1 8.4 10.8 %v/v Site Elevation above sealevel 1978 Ft Inlet Static Pressure to Wet Scmbber -13 Inches w.g.

- - - - - - - - ·- - - - -- -

## FiguresFigure 1- UTAC Line 1 11/5/2012Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and nlden

Green Balls Downdraft Drying 1 Cyclone

Downdraft

Drying 2 Cyclone

Preheat Kiln

To Atmosphere 

# 1**I)~'** Stack Venturi Scrubber Natural Gas**~.........** Coal Primary Cooling

Cooling

Air To Cooler Stack

Final Cooling

Cooling

Air Finished PelletsFigure 2- UTAC Line 2 11/5/2012Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden

Green Balls Downdraft Drying 1 Cyclone

Downdraft

Drying 2

Venturi Scrubber Cyclone

Preheat

To Atmosphere 

# r

Stack

2a To Atmosphere 

# r I 

# I
I 

# )(7 )'

Venturi Scrubber Stack 2b Natural Gas

Coal Primary Cooling

Cooling

Air To Cooler Stack

Final Cooling

cooling

Air Fin·1shed PelletsFigure 3 -Tilden Line 1 11/5/2012Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden

To North

Stack

To South

Stack

To South

Stack

Green Balls

# -s?~**~I** Updraft Drying ESP

Downdraft Drying 1 Downdraft Drying 2 Preheat

Cyclone

Cyclone Cyclone

Kiln Natural G"

••••••••• Coal 

## I

# ~Primary Cooling

Cooling

Air To Cooler Stack

Final Cooling

Cooling Air Finished Pellets

# Attachment 1 DuconInformation on Spray DryerAbsorber MaximumFlow Rate Capacity (Ducon information is forthcoming.)

# Attachment 2 FL SmidthInformation on CirculatingFluidizedBedAbsorber MaximumFlowRate CapacityFrom: Jeppe Sorensen [mailto:ieppe.sorensen@flsmidth.com] 

### Sent: Thursday, November 01, 2012 3:04 PM To: Adams, Jason M Cc: Jacob Sondergaard 

### Subject: RE: UTAC 

## 1 Tilden assistance requested -ASAP Hej Jason Utac #1: Gas volume to be treated: 530,000Nm3/h The FLS GSA max size at this point in time is 635,000Nm3/h It is FLS's understanding that a normal turndown ration for a pelletizer is 20%. The FLS GSA turndown ration is 50% If a lager GSA operating range is required , FLS suggest a re-circulating gas duct to maintain the GSA fluidization. FLS has proposed 1 GSA unit for UTAC #1 as the gas volume to be treated is 530,000 Nm3/h Utac #2: Gas volume to be treated: 1,060,000Nm3/h The FLS GSA max size at this point in time is 635,000Nm3/h It is FLS's understanding that a normal turndown ration for a pelletizer is 20%. The FLS GSA turndown ration is 50%. FLS has proposed 2 GSA unit for UTAC #2 as the gas volume to be treated is 1,060,000 Nm3/h
Tilden #1: Gas volume to be treated from lA: 926,064Nm3/h Gas volume to be treated from 1B: 343,327Nm3/h Gas volume in totai:1,269,391Nm3/h FLS assumed upstream regulating dampers, please see FLS drawing 01504689 The FLS GSA max size at this point in time is 635,000Nm3/h It is FLS's understanding that a normal turndown ration for a pelletizer is 20%. The FLS GSA turndown ration is 50% Operating 2 parallel GSA units will increase the turndown ratio to 75%. If a lager GSA operating range is required , FLS suggest a re-circulating gas duct to maintain the GSA fluidization.

FLS has more than 50 GSA units operating around the world including LKAB pelletizing plants in Sweden. Jason let me know if this information is what you are looking for. leppe Sorensen Sr. Process Engineer Direct 610-264-6790 · jeppe.sorensen@flsmidth.com