CLIFFS 

CLIFFS NATURAL RESOURCES INC. 

200 Public Square, Suile 3300, Cleveland, 0 1-1 44114·2315 

P 216.694.5700 clillsnolumlrcsourcos.com 

November 20,2012 

VIA ELECTRONIC MAIL (hcdman.susan@epa.gov) 

Dr. Susan Hedman, Ph.D. 

Regional Administrator 

U.S. EPA Region 5 

77 W. Jackson Boulevard 

Mail Code: R-19J 

Chicago, IL 60604-3507 

Rc: Cliffs Natural Resources' Regional Haze Proposal for Taconite Facilities 

Dear Dr. Hedman: 

Thank you for your time and attention concerning the effect of the proposed Regional Haze 

Federal Implementation Plan for the taconite industry (the "BART FIP") on the four affected facilities 

operated by Cliffs Natural Resources (Notihshore, Hibbing Taconite, United Taconite, and Tilden 

Mining). Based on our most recent discussion, Cliffs has prepared new information that Cliffs' requests 

EPA consider, and that contains the following elements: 

(1) Commits to natural gas and other low-sulfur fuels to displace coal; and 

(2) Accepts low-NOx burners as a "presumptive BART" technology with a 

commitment to evaluate and install these bumers on a trial basis to confirm that 

they can meet pellet quality and energy efficiency benchmarks for feasible use as 

BART at Cliffs' taconite furnaces; and 

(3) Agrees to install Advanced Process Controls to facilitate implementing LNB 

while potentially mitigating a portion of any potential adverse impacts to pellet 

quality and energy efficiency; and 

(4) Agrees to continuous emission monitors to capture the NOx reduction benefits 

from innovations and to provide a basis for establishing appropriate NOx 

emission limits in the future. 

This proposal provides a pathway for achieving the S02 and NOx reductions anticipated in the proposed 

BART FIP while protecting the taconite industry from changes that can adversely affect two attributes 

critical to our global competitiveness: pellet quality and energy efficiency. The attachment to this letter 

provides the details that you have requested for these conceptual proposals and identifies the new 

information that supports the changes to the proposed BART FIP. 

Cliffs believes that this proposal provides a mutually beneficial alternative to the current 

proposed BART FTP and we ask that EPA incorporate Cliffs' proposal into the final BART FIP rule to 
Ms. Susan Hedman 

November 20, 2012 

Page 2 

mitigate the serious risk of both technical and commercial uncertainty for Cliffs' taconite operations, 

while meeting EPA's regulatory responsibilities. 

If you, or your staff, have any questions regarding Cliffs' proposal, please do not hesitate to contact me. 

Si~~ C.JJL@ 

David T. Cartella 

• CLIFFS 

DAVID T. CARTELLA 

VP, Global Environmental Affairs & Counsel 

P 216.694.4380 (O) 216.212.7817 (M) David.Cartella@CiiffsNR.com 

CLIFFS NATURAL RESOURCES 

200 Public Square, Suite 3300, Cleveland, OH 44114 

cc: David Thornton, MPCA 

Lynn Fiedler, MDEQ 

Mary Gade 

Michael Long 

Scott Gischia 

Douglas A. McWilliams 
Cliffs Natural Resources' Regional Haze Proposal for Taconite Facilities 

This document presents a regional haze proposal for EPA's consideration in response to the 

proposed Regional Haze Federal Implementation Plan for the Taconite Industty published August 15, 

2012 (the Proposal). The Proposal protects Cliffs' taconite facilities from installing new burner 

technology that undercuts the pellet quality and energy efficiency attributes critical to Cliffs' global 

competitiveness. Cliffs' Proposal is summarized in the table below and explained in detail in the narrative 

that follows the table for each of Cliffs' affected taconite furnaces. 

NOx Limit 

NO/ mmbtu 

1.2 lb NO/mmbtu 1.2 lb NO/mmbtu 1.2 lb NO/ mmbtu 

(effective (effective 6 months after (effective 6 months after (cft"cctive 6 months after immediately) installation within 30, 42, installation within 48 and 54 installation within 36 

54 months, subject to months, subject to months, subject to 

presumptive BART presumptive BART presumptive BART 

feasibility demonstration) feasibility demonstration) feasibility demonstration) 

S02Limit 19.5 lbnlf 88 lb/hr Combined limit of 529 lb/hr I 00% Gas- Line I 

30-day rolling average basis 

(effective (effective immediately) within 54 months for Line I (effective within 12 

immediately) and Line 2 (based on 155 lbs months, S02 limit based 

S02/hr for Line I and 374 

lbs S02/hr for Line 2) using on CEMS within I year) 

existing CEMs. 

Advanced Not required First line: Within 24 First line: Second line: Prototype Installed 

Process months Within 24 Within 36 (within 12 months) 

Controls months months 

Second line: Within 36 

months (depending (depending on (Energy on prototype 

Efficiency Third line 3: Within 48 prototype installation 

Program) months installation success) 

success) 

(depending on prototype 

installation success) 

CEMS NO, installed on NO, installed on waste Currently installed and NO, & S02 installed on 

waste gas stacks gas slacks operating waste gas stacks 

(within 18 (within 18 months) (within 18 months) 

months) 

1 
In summary, Cliffs proposes to achieve S02 emission reductions by transitioning from high 

sulfur coal to natural gas and other low sulfur fuels. Cliffs proposes NOx reductions by installing low NOx 

burner technology (LNB) on one straight grate furnace and on one grate kiln furnace to determine if they 

can be demonstrated as feasible for Cliffs' furnaces. If LNB is demonstrated to be feasible, Cliffs will 

install LNBs where necessary to meet the BART limits. Key elements of the feasibility determination 

include: 

1. Cliffs proposes to demonstrate whether LNB technology can cost-effectively 

achieve NOx reductions while maintaining pellet quality at each of the two 

primmy types of furnaces.' Cliffs will conduct feasibility engineering for the 

straight grate furnaces at Hibbing Taconite within 12 months. This repmt will 

include anticipated cost, NOx rate, energy penalty, pellet quality issues, and the 

projected installation and permitting schedule based on the burner design. Cliffs 

will proceed with feasible LNB design specifications to fabricate and install LNB 

technology on one of the lines at Hibbing within the next 12 months following 

feasibility engineering? Cliffs will collect information on actual energy penalty, 

quality impacts, NOx rates and costs per ton of NOx reduced and submit a 

demonstration repmt within six months after installation (a total of 30 months 

from acceptance of this proposal).2 

2. Cliffs will concurrently proceed with a similar grate-kiln furnace trial at Tilden 

Line I. The grate-kiln furnace feasibility evaluation is expected to need more 

time. The feasibility engineering report covering the criteria indicated above will 

be complete within 18 months. The design and installation of the trial LNB will 

be complete within 30 months. The demonstration report will be submitted six 

months after installation (36 months from acceptance of this proposal). If the 

LNB demonstrations are successful, Cliffs will install feasible LNB technology 

on one additional straight grate furnace and one additional grate kiln furnace 

eve1y year after completing the demonstrations. 

3. If the successful LNB demonstrations prove that the technology can meet 1.2 lbs 

NOJMMBtu as proposed by EPA, these limits will become effective six months 

after LNB installation is complete to allow time for shakedown periods and 

process optimization adjustments. If the successful LNB demonstrations prove 

the technology reduces NOx but cannot cost-effectively achieve 1.2 lb 

NOJmmbtu consistently while meeting the criteria for pellet quality and energy 

efficiency, Cliffs will propose an alternate NOx emission limit reflecting what 

LNB can consistently achieve. If the LNB demonstration concludes that the 

technology is not feasible for a furnace type, Cliffs will propose an alternate NOx 

1 Cliffs provided new information in its comments from EPA's LNB vendors that indicate the data from LNB testing 

and installations performed to date are insufficient to generalize that LNB is feasible for all taconite furnaces. The 

vendors agree that the furnace-specific analysis offered by Cliffs above is necessary before we can determine if 

LNB technology causes unacceptable pellet quality, energy penalty, or unacceptable costs for taconite furnaces. 

See sections IV.C, E.2.a, & F.1 of Cliffs' 9/28/12 comments and Attachments F, I, Y, U & AA (EPA-R05-0AR-2010-

0037-0045, -0047, -0052) 2 Installation schedules are based on reasonably expected conditions that do not include delays beyond Cliffs' 

control. LNB installations are expected to require more fuel, which may trigger significant air permitting 

requirements for other pollutants that may require more time than has been allotted in the above schedule. Any 

enforceable milestone schedule should account for these and other potential delays beyond Cliffs' reasonable 

control. 

2 
emission limit using valid CEMs data that reflects the use of good combustion 

practices with any new Advanced Process Controls (APC) that can be effectively 

implemented. Cliffs proposes to install a prototype system for APC at Tilden 

within 12 months and will implement APC on two additional furnaces each year 

thereafter if the systems are successful. The APC are designed to improve 

process stability, which should improve energy use and combustion efficiency. 

They are also expected to reduce NO, emissions and should serve as a valuable 

tool to improve LNB performance and help mitigate any adverse pellet quality 

impacts due to LNB. 

4. The following three objective criteria will be used to determine ifLNB is feasible 

for Cliffs' furnaces: 

a. Furnace-specific degradation in pellet quality from baseline statistical 

performance using pellet quality specifications expressed in objective values for 

compression, before tumble sizing, after tumble sizing, R40 reducibility, lowtemperature disintegration, swelling and contraction. 

b. An energy penalty greater than 30% over baseline energy consumption before 

LNB installation. This high energy penalty reflects additional fuel demand that 

undercuts energy efficiency and generates greenhouse gas (GHG) emissions and 

other pollutants that may trigger independent regulatmy requirements or 

permitting obligations. Increased energy use to this degree is not consistent with 

good energy policy. 

c. The cost per ton of NOx reduced must remain within EPA's cost effectiveness 

thresholds. Some additional costs may be incurred to mitigate energy penalty or 

pellet quality impacts. At some point, additional costs may render LNB costineffective in a patticular application. EPA will provide a cost-effectiveness 

threshold consistent with other regional haze precedent benchmarks for this 

objective criterion.3 

5. Under this proposal, EPA would determine based on the demonstration provided 

by Cliffs whether the LNBs meet the criteria for feasibility set forth above for 

Cliffs' straight-grate furnaces at Hibbing and separately for Cliffs' grate-kiln 

furnaces at Tilden and United. EPA would also determine based on the alternate 

NOx limits submitted how to revise the NOx emission limitations in the 

implementation plan to reflect this new information. Each of these 

determinations would be a final agency action subject to judicial review. 

Cliffs' proposal is designed to be implemented within five years of plan approval in accordance 

with 40 CFR 51.302(c)(4)(iv). If emission limitations must be revised or established after the rule is 

finalized, the agency will have time within the five-year period to amend the implementation plan to 

reflect the appropriate emission limits. Therefore, interim limits are not believed to be necessary. 

3 One relevant regional haze cost-effectiveness benchmark is in EPA's proposed partial approval of the Michigan 

Regional Haze SIP. EPA proposes to find that no additional control equipment constitutes BART for so, after 

concluding that $3,500 per ton for dry flue gas desulfurization was not cost effective for St. Mary's Cement. 77 Fed. 

Reg. 46912, *46921 (August 6, 2012) 

3 
Cliffs acknowledges that additional emission reductions for regional haze pollutants may be 

necessary at one or more of its facilities to meet the one-hour S02 and one-hour NO, National Ambient 

Air Quality Standards (NAAQS). Minnesota's approved long term strategy (LTS) for regional haze 

includes an express obligation for each Minnesota facility to develop modeling and plans for achieving 

any necessary emission reductions to meet its NAAQS obligations by June 30, 2017. Cliffs anticipates 

additional regional haze emission reductions will be motivated by its NAAQS obligations. MPCA's long 

term strategy has established an enforceable mechanism for securing these additional regional haze 

emission reductions. 

The following sections apply Cliffs' Proposal to each of Cliffs' fumaces subject to BART under 

the Regional Haze provisions of the Clean Air Act. 

NORTHSHORE MINING: Northshore operates two straight-grate fumaces and two process 

boilers subject to BART that bum natural gas as their primmy fuel. 

I) Northshore will immediately meet the proposed BART FIP limit of 1.2 lbs NO)MMBtu (30-

day rolling average) for Fumaces 11 and 12 and demonstrate compliance within the 18-month time line in 

the proposed BART FIP rule based on newly installed continuous emission monitors (CEMs) on the 

waste gas stacks. 

2) Northshore will also meet the proposed BART FIP limit of 0.085 lb NOjMMBh1 (30-day 

rolling average) for Process Boiler #I and Process Boiler #2 within the 60-month timeline in the proposed 

BART FIP rule. 

3) Northshore will meet a 19.5 lb S02/hr emission limit (30-day rolling average) for Furnace 11 

and Furnace 12 by burning natural gas. This limit uses the same emission factor that EPA used in its 

proposed FIP rule (0.0651 lb S02/long ton pellet produced) but we multiply the factor by maximum 

production capacity. EPA's proposed FIP limits (16.3 and 17.1 lb S02/hr respectively) are multiplied by 

average production rates, which inappropriately reduce production capacity at Northshore.' Cliffs 

proposes that EPA remove the 80% minimum S02 control efficiency obligation for these fumaces, which 

EPA does not impose on any other natural gas-fired taconite furnace as a separately enforceable 

obligation.' 

5) Cliffs will demonstrate compliance with the S02 limits by periodic stack tests.6 Northshore 

can demonstrate S02 compliance immediately if CEMs are not required in the final rule. 

HIBBING TACONITE: Hibbing operates three straight-grate taconite pelletizing fumaces of 

similar design burning natural gas. 

1) Cliffs and EPA agree that existing scrubber controls constih1te BART for the Hibbing natural 

gas-fired fumaces, but the S02 emission limits must reflect the full variability of the ore body. Cliffs 

provided new test data over an extended period of time to help EPA develop a large enough database to 

4 See section IV.D.3 of Cliffs' 9/28/12 comments (EPA-R05-0AR-2010-0037-004S). 5 BART is defined as the "emission limitation based on the degree of reduction achievable through the application 

of the best system of continuous emission reduction ... " 40 CFR 51.301. Northshore's SO, emission limitation is all 

that is required. Also requiring a demonstration of control efficiency is unnecessary and beyond what BART 

requires. See alsop. 35 of Cliffs' 9/28/12 comments (EPA-ROS-OAR-2010-0037-004S). 6 See section V.A of Cliffs' 9/28/12 comments (EPA-R05-0AR-2010-0037-0045). 

4 
mn a statistical analysis to determine the upper predicted limit (UPL) for S02 when properly operating 

BART controls.7 Since the three furnaces at Hibbing are the same type and size and the ore is from the 

same mine, Cliffs combined the test data and the statistical analysis to produce an emission limit of 88 lbs 

SO,/hr on a 30-day rolling average basis for each furnace. This is preferable to the proposed BART FIP 

limit, which is based on the average value from a single stack test for each furnace and is not 

representative of normal process variability. 

2) Cliffs will demonstrate compliance with the S02 limits by periodic stack tests. Hibbing can 

demonstrate S02 compliance immediately ifCEMs are not required in the final rule.' 

3) Cliffs and EPA have no data on the pellet quality effects of installing low NOx burners on 

straight grate furnaces. EPA relies on pilot testing conducted by Fives Nmth America for the Essar 

installation, which did not introduce pellets and is not a retrofit application. Essar was able to design its 

furnace with LNB, while Hibbing will need to make retrofit burners work in its existing furnace design 

constraints.' Cliffs agrees that the Essar test results are a positive development and we have engaged 

Fives to work with furnace design engineer, Metso, to develop a way to test LNBs on pellets for Hibbing. 

Metso has warned Cliffs that the retrofit application for the Hibbing furnaces could have a significantly 

higher energy penalty than the new furnace designed for Essar. Cliffs is willing to conduct the testing 

necessary to evaluate pellet quality impacts and energy penalty. If these criteria can be resolved within 

the bounds of preserving pellet quality, minimizing energy penalty and cost-effectiveness, Cliffs will 

install LNBs on all three of the Hibbing furnaces. 

Cliffs proposes that LNBs be designated as the presumptive BART determination for Hibbing 

Line I, Line 2 and Line 3, with a presumptive emission limit of 1.2 lb NOxfMMBtu on a 30-day rolling 

average basis using CEMs. These presumptive limits will become effective within 6 months after 

installing LNB. As indicated above, LNB will be installed on a trial basis o1i the first line within 30 

months. If EPA's presumptive BART is validated after testing, Cliffs will have installed LNB on the first 

line 1 and will proceed to install LNBs on the second line within 12 months and the third line within 24 

months of EPA's approval of the demonstration repmt excluding permitting and other delays beyond 

Cliffs' control. 

If the successful LNB demonstrations prove the technology reduces NOx but cannot costeffectively achieve 1.2 lb NOxfmmbtu consistently while meeting the criteria for pellet quality and energy 

efficiency, Cliffs will propose an alternate NOx emission limit reflecting what LNB can consistently 

achieve. If the LNB demonstration concludes that the technology is not feasible for Hibbing based on the 

objective pellet quality criteria representing Hibbing's baseline statistical performance for the criteria 

listed above or the energy penalty exceeds 30% with cost-effective mitigation measures, Cliffs will 

propose an alternate NOx emission limit using valid CEMs data that reflect the use of good combustion 

practices with any new advanced process controls that can be effectively implemented. 

Cliffs is scheduled to install advanced process controls at Hibbing at the first line in 24 months, at 

the second line in 36 months, and at the third line in 48 months, if the prototype at Tilden proves 

successful. The Advanced Process Controls are designed to improve energy and combustion efficiency 

and they are expected to reduce NOx emissions, improve LNB performance, and help mitigate potential 

adverse pellet quality impacts due to LNB. Any alternate NOx limit proposed by Cliffs is expected to 

reflect NOx performance with the benefit of these advanced process controls. 

7 See section IV.D.3 of Cliffs' 9/28/12 comments and Attachment N (EPA-R05-0AR-2010-0037-0045, -0051). 

8 See sections V.A. and B of Cliffs' 9-28-12 comments and Attachments R-T (EPA-R05-0AR-2010-0037-0045, -0051, 

-0052). 

9 See section C.2.a of Cliffs' 9-28-12 comments and Attachment G (EPA-R05-0AR-2010-0037-0045, -0047). 

5 
UNITED TACONITE: United Taconite is the most complex of the four Cliffs' facilities. It 

operates two grate-kiln furnaces on mixed solid and gaseous fuels. Based on new information provided 

during the comment period, installing add-on controls for S02 is not cost-effective for the United furnaces 

when the baseline emission rates reflect the amount of natural gas in the current and projected fuel mix. 10 

Though add-on controls will not be required, Cliffs is achieving significant S02 reductions with its lowsulfur fuel mix. United completed a complicated permitting process for the Green Production Process 

(GPP) in 2011, which imposed NO, limits and natural gas restrictions to control NO, emissions. United 

is interested in increasing natural gas usage even further as part of its dual strategy to increase production 

and meet the one-hour S02 NAAQS, and will rely on NO, reductions from LNBs, if feasible, and a GPP 

permit modification to increase natural gas usage as needed. 

1) Cliffs proposes low-sulfur fuels as BART for United Line 1 and Line 2.ll United will meet a 

combined BART S02 limit of 529 lbs S02/hr within 54 months (based on 155 lbs SO,!hr for Line 1 and 

374 lbs S02/hr for Line 2) on a 30-day rolling average basis using existing CEMs. These limits reflect the 

use of low sulfur fuels, more natural gas, and they utilize the higher sulfur emission factor for the standard 

(acid) pellets produced by United as documented in the comments of US Steel. 12 The schedule reflects the 

time needed to address permit limits that currently restrict the use of natural gas. 

2) Cliffs cannot assume that LNB will work based on EPA's data from the Minntac installation 

of LNB technology because the United grate-kiln furnaces are significantly different in material respects. 

First, Minntac has not generated data for its LNBs on solid fuels, which are essential for United given its 

current GPP permit constraints on using natural gas.

13 Second, Minntac achieves a significant amount of 

its NO, reductions in the preheat zone with smaller burners that have limited effect on pellet quality. 14 

United's design does not have preheat burners, so all of its NO, reduction must come from the retrofit of a 

10 See section E.2.b, E.3 of Cliffs' 9-28-12 comments and Attachment BB (EPA-R05-0AR-2010-0037-0045- 0052). 

Cliffs provided new information regarding the actual baseline S02 emission rates that reflect the current use of 

lower-sulfur fuels for the grate-kiln furnaces at United and Tilden. When the actual baseline emission rate is used 

consistent with EPA guidance, add-on S02 controls are not cost effective for Cliffs' grate kiln furnaces. See sections 

IV.E.2.b, E.3 of Cliffs' 9/28/12 comments and Attachments L & BB (EPA-R05-0AR-2010-0037-0045, -0050, -0052). 

This offers EPA the opportunity to treat Cliffs' grate kiln furnaces comparably to the US Steel grate-kiln furnaces at 

Keetac and Minntac. The proposed BART FIP currently requires S02 controls for Cliffs but not for US Steel resulting 

in lb/ton S02 rates on Cliffs' grate-kiln furnaces that are four times more stringent than the Keetac lb/ton S02 

emission rates. See 77 Fed. Reg. 49308, 49319, 49324-25 (Aug. 15, 2012). 11 Cliffs provided new information on its intent to continue to use a lower-sulfur mix of fuels at the United and 

Tilden lines subject to BART in order to meet regional haze and the S02 NAAQS obligations. See section IV.E.4 of 

Cliffs' 9/28/12 comments (EPA-R05-0AR-2010-0037-0045). 12 See section 5 of US Steel's 9/28/12 comments (EPA-R05-0AR-2010-0037-0044). 13 See U.S. Steel Minntac, line 6 Low NO, Main Burner Final Report & Facility NOx Management at 12 (Dec. 2011) 

(EPA-R05-0AR-2010-0037-0039); U.S. Steel Minntac, line 7 Low NO, Main Burner Final Testing Report at 7-8 (May 

2011) (EPA-R05-0AR-2010-0037-0039). 14 Minntac invested capital to retrofit the design of furnaces in the late 1980's to include preheat burners for its 

grate-kiln furnaces which facilitated a significant portion of the furnace's NO, reduction while mitigating energy, 

heat balance and quality parameters associated with a kiln burner LNB retrofit. See section IV.D.2 of Cliffs' 

9/28/12 comments (EPA-R05-0AR-2010-0037-0045). The existing design of United and Tilden do not have preheat 

burners, so 100% of any NO, reduction must come from the primary burner in the grate kiln furnace, a much more 

challenging proposition. This reduces vendors' options for mitigating energy penalty and increases the potential 

pellet quality ramifications for Cliffs' grate-kiln furnaces. This is further justification for the furnace-specific testing 

referenced above. 

6 
single burner that alone dictates combustion parameters that affect pellet quality. 15 Cliffs agrees that the 

results at Minntac are a positive development, but Cliffs and EPA need more data to establish that LNBs 

constitute BART for United's two grate kiln furnaces. Cliffs has engaged the Minntac burner design 

company, Coen, to work with furnace design engineer, Metso, to develop a way to test LNBs on pellets 

for the grate-kiln furnaces at United and Tilden. Metso has warned Cliffs that the retrofit applications for 

the United and Tilden grate-kiln furnaces could have a significantly higher energy penalty and more 

significant pellet quality impacts than Minntac's application. Cliffs is willing to conduct the testing 

necessmy to evaluate pellet quality impacts and energy penalty. If these criteria can be resolved within 

the bounds of cost-effectiveness, Cliffs will install LNBs on the two United furnaces. 

Cliffs proposes that LNBs be designated as the presumptive BART determination for United Line 

I and Line 2, and impose the 1.2 lb NOJmmbtu emission limit on a 30-day rolling average basis based on 

CEMs. These presumptive limits will become effective six months after Cliffs conducts a trial of LNB 

technology on one of its grate kiln furnaces. As indicated above, Cliffs will conduct feasibility 

engineering within 18 months and install feasible LNB on a trial basis on one of Cliffs' grate kiln 

furnaces within 30 months. If EPA's presumptive BART is validated for the grate-kiln furnace after 

testing, Cliffs will install LNB on the second grate kiln within 12 months of EPA's approval of the 

demonstration repott, and within 18 months of EPA's approval of the LNB demonstration report for the 

third grate kiln furnace. 

If the successful grate kiln LNB demonstration proves the technology reduces NO, but cannot 

cost-effectively achieve 1.2 Ib NOJmmbtu consistently while meeting the criteria for pellet quality and 

energy efficiency, Cliffs will propose an alternate NO, emission limit reflecting what LNB can 

consistently achieve. If the LNB demonstration concludes that the technology is not feasible for United, 

Cliffs will propose an alternate NO, emission limit using valid CEMs data that reflects the use of good 

combustion practices with any new advanced process controls that can be effectively implemented. Cliffs 

is scheduled to install advanced process controls at United on the first line in 24 months and at the second 

line in 36 months, if the prototype installed at Tilden proves successful. Any alternate NOx limit 

proposed by Cliffs is expected to reflect NO, performance with the benefit of these advanced process 

controls. 

TILDEN MINING (Michigan): Tilden's Line I is a grate-kiln furnace that burns a combination 

of solid and gaseous fuels to make a fully fluxed pellet. Tilden is processing iron ore from an ore body in 

Michigan that contains more sulfur that the ore processed by taconite mining operations in northeast 

Minnesota. 

I) Cliffs is willing to limit Tilden Line I to natural gas fuel as an alternative for S02 control. 

Cliffs has vety limited data for S02 emissions when burning I 00% natural gas. Cliffs proposes that 

Tilden collect one year's worth of CEM data and use the UPL calculated for that database to set the new 

S02 emission limit. Tilden will submit the alternate S02 emission rate to EPA within 60 days after the 

CEM has collected one year's worth of valid data and EPA will proceed to amend the regional haze rule 

to include this numeric S02 emission limit reflecting natural gas operation of Line I. 

2) Cliffs proposes that LNB be designated as the presumptive BART determination for Tilden 

Line I and that the presumptive emission limit be 1.2 Ib NOJmmbtu on a 30-day rolling average basis 

based on CEMs. The presumptive limit will become effective 6 months after the LNB grate kiln 

15 See section C.1 of Cliffs' 9-28-12 comments and Attachments H & Y (EPA-R05·0AR-2010·0037·0045, -0047, -

0052). 

7 
demonstration has been validated by EPA and LNB is installed on Tilden Line I (expected 36 months 

after the effective date of the rule). 

If the successful grate kiln LNB demonstration proves the technology reduces NOx but cannot 

cost-effectively achieve 1.2 lb NO,/mmbtu consistently while meeting the criteria for pellet quality and 

energy efficiency, Cliffs will propose an alternate NOx emission limit reflecting what LNB can 

consistently achieve. If the LNB demonstration concludes that the technology is not feasible for Tilden 

Line I, Cliffs will propose an alternate NOx emission limit using valid CEMs data that reflects the use of 

good combustion practices with any new advanced process controls that can be effectively implemented. 

Cliffs proposes to install prototype advanced process controls at Tilden in the next 12 months. Any 

alternate NO, limit proposed by Cliffs is expected to reflect NO, performance with the benefit of these 

advanced process controls. 

8