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 submitted by 

e-mail to me on October 30, 2012 pertaining to the cost effectiveness calculations in Cliffs' 

comments on EPA's proposed Regional Haze Federal Implementation Plan for taconite 

furnaces. The response is in the form of a letter from Mike Long with three referenced 

attachments providing technical support. Please note that we include a placeholder for one of the 

vendors because they were not able to respond from their New Jersey office in the time allotted 

due to severe weather challenges. We will supplement the response when that information is 

available. 

Please contact me with 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 
---------------------------------------------------------------------3 7 Offices in 18 Countries This message 

is confidential and may be legally privileged or otherwise protected from disclosure. If you are 

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visit www.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 1 0-30-12.pdf ll?J -Attachment 2 Cliffs 

Response to EPA Questions on Regional Haze FIP Comments 1 0-30-12.pdf m -Attachment 3 Cliffs 

Response to EPA Questions on Regional Haze FIP Comments_1 0-30-12.pdf 
·~CLIFFS 

CLIFFS NATURAL RESOURCES INC. 

1100 Su;J(~rior Avenue, Suit(1 i 500, C1Bve!and, OH .'l~ 114-2.544 

P 216 694_5700 F 216.69·~..1880 ct!Jfsna~t;ralrosources.corn 

November 9, 2012 

VIA ELECTRONIC MAIL (wagner.william@epa.gov) 

William Wagner 

U.S. EPA Region 5 

Office of Regional 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 the Proposed Regional Haze FIP for Taconite Furnaces 

Dear Bill: 

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 of EPA's questions is addressed 

in this letter and the attachments prepared by Barr Engineering in consultation with vendors. 

One of the 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 it becomes 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 of the 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 of emission 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 of the allowable emission rates used by EPA. The actual emission reduction is 

significantly lower than the reduction of potential 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. 

Information requested 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 of the 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 of the 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 from the 

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 of control, improves reliability and improves efficiency. 

Information requested 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 of the year 

and did not reflect the facility's production goals for 2013. Therefore, we used the CEM data 

from January to August of2012 and then multiplied these 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 of 729 tpy 

for Line I and 910 tpy for Line 2, in line with the 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 of a control device must be 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 CFR Part 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 of the 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 attributable to iron ore captured by the ESP. 

We appreciate the opportunity to help EPA understand our taconite facilities and to 

clarify our comments on the proposed BART FIP. We would be happy to arrange a conference 

call, if that would be a more efficient way to exchange information to gain an understanding of 

the cost effectiveness analysis, or any other aspect of our comments. 

Sincerely, 

/Michael Long/ · 

Michael E. Long 

MICHAEl E. lONG 

Director- Corporate Environmental Regulatory Strategy and Analysis 

P 216.694.7359 (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 

Steven Rosenthal, U.S. EPA Region V 
Figure 1- UTAC Line 1 

11/5/2012 Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden 

Green 

Balls 

Cyclone 

Downdraft I Downdraft 

Drying 1 Drying 2 

Venturi Scrubber 

Cyclone 

Preheat Kiln 

To 

Atmosphere 

1 

Stack 

Natural 

Gas 

·•••••••••• Coal 

Primary Cooling 

;<;; 

Cooling 

Air 

To Cooler 

Stack 

Final Cooling 

Cooling 

Air 

Finished 

Pellets 
Figure 2- UTAC Line 2 

11/5/2012 Technical 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 

Venturi Scrubber 

Cyclone 

Preheat Kiln 

'--------T+--' 

To 

Atmosphere 

r 

Stack 

2a 

To Atmosphere 

r 

Stack 

2b 

Natural 

Gas 

~········· Coal 

Primary Cooling 

" 

Cooling 

Air 

To Cooler 

Stack 

Final Cooling 

Cooling 

Air 

Finished 

Pellets 
Figure 3- Tilden Line 1 

11/5/2012 Technical Memorandum Re EPA Questions on the 502 Control Cost Analysis for Dry 502 Controls at UTAC and Tilden 

~~ ESP ~ 

To North 

Stack 

To South 

Stack 

To South 

Stack 

~~ ~-ESP I .-----co,~ I I -,. I 

To Cooler 

Stack 

Green --+-1 

Balls 

Updraft 

Drying 

Downdraft 

Drying 1 

Downdraft 

Drying 2 Preheat Kiln 

Cyclone 

Cyclone 

Natural 

G" 

••••••••· Coal 

I 

1 

~~Primary Cooling 

Cooling 

Air 

Final Cooling 

Cooling Air 

Finished 

Pellets 

resourceful. naturally. BARR 

engineering and environmental consultants 

From: Paul Taylor 

Subject: Derivation ofS02 Emission Reductions for United Taconite Lines I and 2 

Date: November 2, 2012 

This is in response to the following item in EPA's 10/31/2012 e-mail (authored by Bill Wagner) to Cliffs 

Natural Resources (care of Doug McWilliams, Squire Sanders LLP): 

InfOrmation needed tor UTAC 

Barr p3 discusses use of CEMs data for 2012 prorated from current production to the capacity 

allowed by the green production project (GPP}. Barr p4 says that the FIP S02 reductions of 1,164 

tpy for Line 1 and 2,475 tpy for Line 2 are incorrect and should be 650 tpy and 760 tpy, respectively. 

The GPP S02 permit limits are 1128 tpy for Line 1 and 2556 tpy for Line 2. (Are these still correct?) 

A 95% reduction from these limits would be 1,072 tpy for line 1 and 2,428 tpy for Line 2. Please 

explain how the lower emission reduction estimates were derived. 

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 and 2, the S02 baseline emissions are based on S02 continuous emission 

monitoring system (CEMS) data for 2012 prorated from current production levels to the full 

production capacity of the Green Production Project (GP P) permit 1 established in August, 2010. The 

2006 BART baseline did not include emissions from coal combustion on Lines 1 and 2 and are not 

representative of expected actual S02 emission rates based on CEMS data. The S02 emiSsion control 

cost calculations use the performance specified by the proposed FIP limit of 5 ppm S02 for CFBA 

scrubbers and the control equipment suppliers' performance guarantee (> 90% removal) for SDA 

scrubbers to calculate the assumed controlled emissions. 

Barr Engineering Co. 332 West Superior Street, Suite 600, Duluth, MN 55802 218.529.8200 www.barr.com 
From: 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 

Fluid Bed analyzer and 660 tons/yr for the Spray Dry Absorber. 

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 Dry Absorber. 

Page 4 states: 

The S02 emission reduction of 1,164 and 2,475 tons per year, for Line 1 and Line 2 respectively, 

listed in Table V-B.ll of the proposed FIP did not accurately consider the anticipated annual 

emissions 1 under the GPP. For CFBA at controlled S02 concentration of 5 ppm, the calculated S02 

reduction is 650 tons per year for Line 1 and 760 tons per year for Line 2. At the baseline emission 

rate and the proposed FIP limit of a 95% S02 control efficiency, S02 concentrations at the outlet of a 

dry FGD on United Taconite Lines 1 and 2 would be below the CFBA supplier performance 

guarantee and the proposed FIP limit of 5 ppm. The S02 emission reduction for SDA was calculated 

at a 90% control efficiency. The SDA equipment supplier proposed a performance guarantee of> 

90% S02 control. Based on this performance guarantee, it is uncertain whether or not the proposed 

FIP limit of 5 ppm S02 could be met with a SDA scrubber. 

1 The cost effectiveness guidance refers to use of "a realistic depiction of anticipated annual 

emissions for the source . .. for the existing sources subject to BART, you will estimate the anticipated 

annual emissions based upon actual emissions from a baseline period." 40 CFR Part 51, App. Y .4.d. 

(sic, should be 40 CFR Part 51, App. Y.IV.D.4.d) 

Responses to EPA's 10/31112 e-mail: 

I. EPA's e-mail states that "The GPP S02 permit limits are 1128 tpy for Line 1 and 2556 tpy for Line 

2" and asks whether these 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 specified on pages A-49 and A-56, respectively, of 

United Taconite's Title V air permit 13700113-005, issued 8/19/2010 (copies attached). 

2. EPA's e-mail asks Cliffs to explain how the lower S02 emission reduction estimates for CFBA (650 

tons/yr for Line 1 and 760 tons/yr for Line 2) were derived. The emission reductions were 
From: 

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 between the "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 should represent a 

realistic depiction of anticipated annual emissions for the source. In general, for the existing sources 

subject to BART, you will estimate the anticipated annual emissions based upon actual emissions 

from a baseline period" The S02 CEMS installed on each indurating furnace stack provide the best 

available data for estimating actual emissions from a baseline period. A baseline period from 

111/2012 through 8/31/2012 was selected because this period is believed to be representative of how 

United Taconite (i) has operated the furnaces since the implementation of the Green Production 

Project ("GPP", the subject of permit 13700113-005), and (ii) anticipates operating the furnaces in the 

future. The actual emissions for this eight month period (i.e., the sum of valid hourly "lb/hr" CEMS 

values) were scaled up to an anuual basis using the ratio of the allowable (annual) to actual (eight 

month) production levels. 

The "anuual emissions with control option" were calculated assuming the proposed BART FJP limit 

of5 ppm S02 • 

Based on the method described above, the S02 emissions reductions were derived for 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) I 2012 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 T pellets/yr assumed in the GPP permit application) ~ 729 tons/yr. 

Annual emissions with control option: 

5 ppm S02 I !,000,000 ppm x 358,758 sdimin x 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. 

Note that the air flow rate is based on the average of 13 stack tests 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 emission reductions: 

Baseline annual emissions (729 tons/yr)- Annual emissions with control option (78 tons/yr) ~ 651 

tons/yr, rounded to 650 tons/yr. 

Note that applying the alternative proposed FIP limit of a 95% S02 control efficiency to the baseline 

annual emissions (729 tons/yr) gives a controlled S02 emission rate (729 x (1-95%) ~ 36 tons/yr) that 

is below the CFBA supplier performaoce guarantee and the proposed F1P limit of 5 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 ppm x 700,135 scf/min x 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 that the air flow rate is based on the average of35 stack tests 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 limit of a 95% S02 control efficiency to the baseline 

aooual emissions (910 tons/y:r) gives a controlled S02 emission rate (910 x (1-95%) ~ 46 tons/yr) that 

is below the CFBA supplier performance guarantee and the proposed FIP limit of 5 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 Efficiency w/o Lime 

MR 001 NOx monitor 

MR 002 S02 monitor 

MR 003 Flow monitor 

POLLUTANT LIMITS 

SV046 

SV097 

What to do 

Opacity: less-than or equal to 20 percent opacity except for one six-minute period 

per hour of not more than 60 percent opacity. 

Total Particulate Matter: less than 0.3 grains/dry standard cubic foot of exhaust 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 of exhaust gas) 

The Permittee shall operate and maintain the control equipment such that it 

achieves an overall control efficiency for Total Particulate Matter: greater than or 

equal to 94 percent control efficiency 

PM < 10 micron: less than or equal to 0.0139 grains/dry standard cubic foot using 

3-hour Average (standard cubic feet of exhaust gas) 

The Permittee 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 percent control efficiency 

PM< 2.5 micron: less than or equal to 0.0139 grains/dry standard cubic foot using 

3-hour Average (standard cubic feet of exhaust gas) 

The Permittee shall operate and maintain the control equipment such that it 

achieves an overall control efficiency for PM < 2.5 nlicron: greater than or equal to 

84 percent control efficiency 

Sulfur Dioxide: less than or equal to 4 lbsfmillion Btu heat input using 3-hour 

Average when only a solid 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 emissions frOm EU 040 to 1293 tons 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. 

Sulfuric Acid 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 under 40 CFR Section 52.21 and Minn. R. 

7007.3000; Minn. R. 7007.0800, subps. 2 and 14 

Title 1 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 1 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 

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 under 40 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 under 40 CFR Section 52.21 and Minn. R. 

7007.3000 

Title 1 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 under 40 CFR Section 52.21 and Minn. R. 

7007.3000 

hdr 

Title 1 Condition: To avoid classification as a major 

modification under 40 CFR Section 52.21 and Minn. R. 

7007.3000 
TABLE A: LIMITS AND OTHER REQUIREMENTS 

Facility Name: United Taconite LLC ~ Fairlane Plant 

Penn it 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 except for one six-minute period 

oer hour of not more than 60 oercent ooacitv. 

Total Particulate Matter: less than or equal to 0.0157 grains/dry standard cubic foot 

using 3-hour Average (standard cubic feet of exhaust 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 for Total Particulate Matter: greater than or 

~~al to 94 percent control efficiencV 

PM < 10 micron: less than or equal to 0.0189 grains/dry standard cubic foot using 

3-hour Average (standard cubic feet of exhaust 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-hour Average (standard cubic teet of exhaust 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 or equal to 4 lbs/million Btu heat input using 3-hour 

Average when only a solid 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. 

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 197 tons using 30-day Rolling Sum rolled daily. 

This condition restri'cts S02 emissions from EU 042 to 2394 tons per year. 

Nitrogen Oxides: less than or equal to 1820 tons using 180-day Rolling Sum rolled 

daily. 

This condition restricts NOx emissions from EU 042 to 3692 tons per year. . 

Sulfuric Acid Mist: Jess than or equal to 15.4 tons using 30-day Rolling Sum rolled 

daily. 

This condition restricts Sulfuric Acid 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 under 40 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 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 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 under 40 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 under 40 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 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 on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite 

Lines I and 2 and Tilden Line I 

Date: November 9, 2012 

This technical memorandum is in response to the items in italic font listed below which 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 of dry S02 controls at United Taconite (UTAC) and Tilden are 

highly dependent upon the design of each induration fumace. There are significant differences between 

the UT AC 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 of the induration furnace processes 

and to adequately respond to the questions posed by EPA, descriptions of induration 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 of grate/kiln induration furnaces 

• A brief description of UTAC Line 1 and 2 traveling grate sections and how the grate design 

affects operation of the induration furnaces and characteristics of the exhaust streams. 

• Responses to EPA questions regarding UTAC Lines I and 2. 

• A brief description of Tilden Line I traveling grate section and the implications of its 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.cotn 
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: November9, 2012 

Page: 2 

General Grate/Kiln Induration Furnace Descriptions 

The Tilden and UTAC induration furnaces are grate/kiln type furnaces. Feed (green balls) to a grate/kiln 

furnace is introduced to a moving grate at the front end of the furnace for drying and pre-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 outlet of the pellet cooler. 

In order to minimize the fuel requirements of the rotary kiln, the grate portion of the induration furnace is 

designed with recuperative heat recovery systems which utilize the hot exhaust from the rotary kiln and 

pellet cooler to dry and preheat the green ball pellets. The inside of the moving grate enclosure contains 

baffles which are used to direct the flow of hot 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 heat recovery. 

It is the differences in the design of grate 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 of each exhaust stream. Most of the water in the green balls is driven 

off in the first sections of the 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 of the traveling grate and kiln sections of a 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 will be present in all induration fumace exhaust streams. Simplified flow 

diagnuns of each 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 of Tilden Line 1. In the following sections of 

this technical memorandum, there is a description of the grate sections for each induration furnace. This 

is followed by the questions raised by EPA regarding the dry S02 control system design used for the S02 

control cost analysis and the 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 

exhaust which flows directly into the preheat section. After exiting the preheat section, the kiln exhaust is 

directed via ductwork to Downdraft Drying I for further heat recovery. The hot exhaust from the pellet 
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: November9, 2012 

Page: 3 

cooler is directed via ductwork to Downdraft Drying 2. Both Downdraft Drying 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 damaging them. 

UTAC Line I has a single exhaust gas system with one exhaust gas fan and one stack. All exhaust gases 

exiting the induration furnace are routed through this scrubber system, process exhaust fan and stack. 

UTAC Line 2 production rate and physical size is twice that of Line I, which requires the gas flow rate 

through Line 2 to be approximately twice that of Line 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 on the north side of Line 2 and the other is located on 

the south side. The systems are mirror images of one another. The Line 2 exhaust gas systems are both 

the same size and have essentially the same gas compositions. 

All three exhaust gas fans have approximately the same design flow capacity. 

Response to EPA questions on UTAC Lines 1 and 2 

The EPA questions provided in the October 31,2012 email of the UTAC Line 1 and 2 dry scrubber 

system design basis are listed below followed by a response. 

Barr pp 8&9 say that Line I has one process blower and Line 2 has two process blowers, and Line 2 can 

operate on one process blower. Barr argues that two FGDs are necessarv tor Line 2 to maintain gas 

velocity. !(that were true, Line I would also need parallel halt:sized FGDs fOr low flow conditions, which 

Barr has not prooosed. 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 not aware of a need for parallel scrubbers to handle turn-down conditions at these boilers. 

Response- Parallel Scrubbers on UT AC Line 2 

The total exhaust gas flow rate from UTAC Line 2 pushes the limits of the maximum design flow 

capacity of the 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 parallel 
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: 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 meet the S02 control performance levels specified in the 

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 

not recovered 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 each vendor are located in Attachments I and 2 to the memorandum. 

Response- Dry Scrubber Turndown 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% of capacity, gas flow rates in illy S02 scrubbers are not 

high enough to keep the spent reagent in suspension for transport from the absorber into the baghouse for 

collection. In a circulating fluidized bed absorber gas flow rates below 50% of capacity are not 

sufficiently high to keep reagent suspended in the fluidized bed absorber. 

If the 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 of estimating S02 control costs, Cliffs Natural Resources has assumed that with only one 

fixed speed exhaust gas fan a dry S02 scrubber turndown rate of 50% is sufficient. This results in a lower 

S02control cost than installation of two small dty scrubbers to accommodate a production rate below 50% 

of capacity. 

UTAC Line 2 cunently has two fixed speed process exhaust gas fans and can operate in a reduced 

production mode with only one process exhaust fan operating. This flexibility in operation is required to 

meet production needs. When operating with only one process exhaust gas fan in service, exhaust gas 

flow rates are reduced to 50% of capacity or less and still maintain the process parameter integrity. If a 

single dry SO, scrubber was used, as proposed by EPA, instead of the two scrubber system as 
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: 5 

recommended by the vendor, the exhaust gas flow rate in the single fan operating mode would be at or 

below the minimum flow rate allowable for a dry S02 scrubber (50% tumdown). By installing two d1y 

scrubbers on Line 2, either exhaust gas dry S02 scrubber can safely operate within its design range when 

Line 2 is operating in single fan mode. 

Barr plO says that new dry ESPs will be installed for particulate control and iron ore recovery. B) What 

is the value o(the additional ore captured by the ESPs v. the wet scrubbers 

Response- Additional Iron Ore Recovery from a dry ESP: 

No additional iron ore will be recovered if a d1y ESP is installed to accommodate installation of a dry S02 

scrubber. If d1y ESPs were installed for this purpose, they would recover the same amount of iron ore 

dust as the existing venturi scrubbers. The primary purpose of both particulate removal systems is to 

protect the process exhaust gas fan from damage by abrasive iron or dust particles. If a dry ESP were 

installed as part of a dry S02 scrubbing system, it would be designed to meet the same exhaust gas dust 

concentration specifications as the existing venturi scrubbers. The current wet scrubbing systems remove 

a sufficient amount of iron ore dust to protect the existiog exhaust gas 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 in the lime/water slurry injected into the absorber will evaporate. This allows capture of the 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. If a dry S02 absorber were installed downstream of wet particulate scrubber, the spent lime would 

not dry in the absorber; instead, it would be 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 protect the exhaust gas fan, installation of dry 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 by the dry S02 scrubber into the system. It would also reduce the 

operating pressure of the induration fumace causing more air infiltration thus reducing the thermal 
From: Jack Kennedy 

Subject: EPA Questions on the SOz Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1 and 2 and 

Tilden Line 1 

Dote: November9, 2012 

Page: 6 

efficiency of the furnace. There is also the potential for the iron ore dust causing adverse reactions in the 

dry scrubber; thus reducing the efficiency of the 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 of UTAC'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 of the 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 of one 

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 considering the control of 

one of the exhaust gas systems with a single scrubber module. 

Process Description Tilden Line 1 

The Tilden Line I 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 of exhaust gas from Preheat to Updraft Drying and Downdraft Drying I. 

Dampers regulate the relative amounts of Preheat 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 of Tilden Line I and are routed to the South Stack. Downdraft 2 is located 

on the north side of Line 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 from the October 31, 2012 email on the Tilden Line I dry scrubber system design basis 

are listed below followed by a response. 

We are pleased that Cliffs has re-evaluated the cost-effectiveness of applying either a Gas Suspension 

Absorption (GSA) system or spray dry absorber (SDA) to the combined exhaust streams from the Line 1 

indurating furnace at your Tilden facility. We note that the estimated total capital investment cost for 

applying these dry-scrubbing options has decreased from $167 million in 2006 to $63 million now. We 

understand that two parallel GSA!SDA modules would be required to treat the entire combined gas 

stream as "gas streams from the lines 2C (from the North Stack) and lines 2A and 28 (from the South 

Stack) will be mixed in a common duct." We also understand that there are significant differences among 

the volumetric flow rates and other characteristics of the three gas streams (which apparently prompted 

Ducon's recommendation that all three exhaust streams be combined). Please provide a simple 

schematic diagram showing existing gas flows associated with the Line 1 indurating furnace and describe 

the characteristics of the three gas stream lsimilarto Table 2 of Barr Engineering's 9!28/12 report). 

Response- Request for Tilden Line 1 Simplified Flow Diagram and Exhaust Stream Data Table: 

Figure 3, a simplified flow diagram of Tilden Line I, is attached to this report per EPA's 10/31/2012 

request. In addition, the previous section of this report includes a process description of Tilden Line I. 

Table 1, a summary of Tilden Line I exhaust stream parameters, is attached to this report per EPA's 

10/31/2012 request. Information in this table is based on the same Cliffs Natural Resources data1 that the 

control equipment suppliers used for the dry S02 scrubber equipment cost estimates which Barr used for 

the S02 control cost analysis. 

Please note that the Tilden Line I South Stack contains the exhaust gas from the Updraft Drying and 

Downdraft Drying I traveling grate zones. Of the three exhaust streams, the two exhaust streams vented 

to the South Stack have the highest moisture content and the lowest temperature. Ducon expressed 

concerns that based on the South Stack temperature and moisture content; the water dew point approach 

temperature 2 would be too low for dry S02 scrubbing. Downdraft Drying 2 exhaust (North Stack) 

1 Tilden Pellet Plant Unit 1 Process Airflow Survey, June 14, 2012. 2 The dew point approach temperature is the difference between the off gas temperature at the inlet of the dry 

scrubber and the water dew point of the off gas exiting the scrubber. In a dry 502 scrubber, a lime/water slurry is 
From: 

Subject: 

Date: 

Page: 

Jack Kennedy 

EPA Questions on the S02 Control Cost Analysis for Dry S02 Controls on United Taconite Lines 1 and 2 and 

Tilden Line 1 

November 9, 2012 

8 

contains sufficient heat to address this concern. So, all three Tilden Line I exhaust streams were 

combined prior to entering the dry S02 scrubbing system to ensure the inlet to tbe dry S02 scrubbing 

system would be maintained at the proper approach temperature under nonnal operating conditions to 

allow proper operation of tbe scrubbing system. The alternative to this approach would be to 

continuously operate a duct burner and burn natural gas to reheat tbe South Stack exhaust to the required 

temperature. 

We would also appreciate further explanation regarding the need for parallel absorber modules even 

though one may be sufficient to handle a gas stream (such as the gas stream with the highest SO, 

concentration) at full production conditions. While we understand that two absorber modules would be 

necessary to handle the combined gas flow from Tilden Line 1, if a smaller gas flow is treated that is 

within the capacitv of a single scrubbing module, would a second module still be needed to handle lowoperation gas flows? For example, we note that the proposal for UTAC Line 1 contains only one scrubber 

module to treat 436,000 acfm. To help us evaluate this issue please provide statements from the 

scrubber vendors explaining how much gas flows to the scrubbers can be "fumed down" and still be 

effective. We also request that this vendor information be compared to tvoical tum-down ratios for Tilden 

Line 1. 

Response- Request for the Basis of the Design Requirements for Parallel Dry S02 Scrubbers on 

Tilden Line 1: 

Statements from each vendor regarding tbe turndown capacity of their dry S02 scrubbers are located in 

Attachments 1 and 2 to the memorandum. 

The combined exhaust gas flow rate from Tilden Line 1 used in the 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 affected by the recent storms along the East Coast and have 

not recovered power. 

injected for 502 control. As water from the lime/water slurry evaporates in the absorber vessel the off gas 

temperature drops. Ducon recommends a 500 F approach temperature to ensure that the lime/water slurry will be 

completely dry at the scrubber outlet and suitable for collection in a baghouse. If the scrubber inlet gas 

temperature is not hot enough, the spent lime particles will not be completely dry and will foul the dry absorber 

vessel, ducts, bag house 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, maximum flow 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 through the South Stack is 771,000 acfm (513,000 scfin). If treatment were limited to the South 

Stack, two parallel scrubbers would be required to address the volume of exhaust to be treated. If 

treatment were limited to the North Stack, one scrubber would be required. Please note that this does not 

take into consideration additional gas flows associated with reheating the exhaust gas to meet minimum 

operating temperature requirements of a dry S02 scrubber. 

Tilden Line I cannot be operated with only one process exhaust fan in service. Therefore, turndown 

capacity was not a factor in selection of parallel dry S02 scrubbers for this application. 

Treatment of individual exhaust streams from Tilden Line I was not considered due to the low South 

Stack exhaust temperature as discussed above. 

This information is necessary to confirm whether or not a GSA or SOA is appropriate for one or more 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 1 and 2 and 

Tilden Line 1 

November 9, 2012 

10 

Response- The Appropriateness of GSA or SDA for one or more of Tilden's Three Exhaust Gas 

Streams: 

As noted in the S02 control cost analysis (Attachment L) submitted with Cliffs Natural Resources' 

September 28, 2012 comments to the draft FIP3

, there are limited options for routing ductwork from 

Tilden Line 1 to a location where a dry S02 scrubber system(s) could be installed. There is insufficient 

space within the induration fumace building to route ductwork from the individual traveling grate sections 

on Line 1 to the available plot space for dry S02 scrubbing on the south side of the building. That is why 

the proposed system is based on tie-ins to the North and South Stacks with a single duct routed across the 

top of the induration furnace building. 

As noted above, additional heat is needed to maintain the approach temperature of the South Stack, and 

combining the South Stack with the North Stack exhaust was used for this purpose in the S02 control cost 

analysis. Treating only the South Stack would require installation and operation of a re-heat system 

which would consume additional natural gas and increase NOx and greenhouse gas emissions. 

3 Comments of Cliffs Natural Resources on Docket ID Nos. EPA-R05-0AR-2010-0954 and EPA-R05-0AR-2010-

0037, Proposed Approval and Promulgation of Implementation Plans; States of Minnesota and Michigan; 

Regional Haze Federal Implementation Plan, 77 Fed. Reg. 49308 (Aug. 15, 2012) ("Proposed Rule") 
Table 1. Stream Characteristics for Tilden Line 1 Exhaust Gas Streams 

Parameter Value Units 

Stream Updraft Drying 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 per year 

Gas Temperature 249 353 301 320 307 degrees F 

Inlet PM 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 sea level 1978 Ft 

Inlet Static Pressure to Wet Scmbber -13 Inches w.g. - - - - - - - - ·- - - - -- -
Figures 
Figure 1- UTAC Line 1 

11/5/2012 Technical 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 

Pellets 
Figure 2- UTAC Line 2 

11/5/2012 Technical 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 

Pellets 
Figure 3 -Tilden Line 1 

11/5/2012 Technical 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 

Ducon Information on Spray Dryer Absorber Maximum Flow 

Rate Capacity 

(Ducon information is forthcoming.) 
Attachment 2 

FL Smidth Information on Circulating Fluidized Bed Absorber 

Maximum Flow Rate Capacity 
From: 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 · 

j eppe. sorensen@fl sm i dth. com