November 26, 2013 

VIA E-MAIL AND FEDERAL EXPRESS 

The Honorable Gina McCa11hy 

Administrator 

U.S. Environmental Protection Agency 

Room3000 

Ariel Rios Buildiog 

1200 Pennsylvauia Avenue, N.W. 

Washington, D.C. 20004 

Mr. Douglas Aburano 

Chief, Attainment Planning 

and Maintenance Section 

Air Programs Branch (AR-18J) 

U.S. Environmental Protection Agency 

77 West Jackson Boulevard 

Chicago, Jllinois 60604 

Rc: Petition for Administrative Reconsideration of the Partial Disapproval of Air 

Quality Implementation Plans for Regional Haze for the States of Michigan and 

Minnesota 

Cliffs Natural Resources Inc. ("Cliffs") hereby petitions the U.S. Environmental 

Protection Agency ("EPA" or "Agency") for reconsideration of the final rule entitled "Approval 

and Promulgation of Air Quality Implementation Plans; States of Michigan and Minnesota; 

Regional Haze; Final Rule," which was published in the Federal Register at 78 Fed. Reg. 59,825 

(Sept. 30, 2013) ("SIP Disapproval"). Cliffs operates four of the seven taconite processing 

facilities for which EPA has disapproved the state Best Available Retrofit Teclmology ("BART") 

determinations of Minnesota and Michigan: three in Minnesota (Hibbing Taconite, N011hshore, 

and United Taconite) and one in Michigan (Tilden). Cliffs submitted extensive comments on 

EPA's proposed SIP Disapproval to Docket Nos. EPA-ROS-OAR-2010-0037 and EPA-ROSOAR-2010-0954. 

Reconsideration is mandated under the Clean Air Act ("CAA'') § 307(d)(7)(B), which 

states that "the Administrator shall convene a proceeding for reconsideration of the rule" when a 

person raising an objection to a rule or procedure can demonstrate that "it was impracticable to 

raise such objection or if the grounds for such objection arose after the period for public 

conm1ent ... and if such objection is of central relevance to the outcome of the rule .... " 

Since the close of the public comment period, additional information has become 

available regarding the availability and effectiveness oflow-NOx bumers ("LNBs") in taconite 

furnaces and the importance of case-by-case fimmce determinations when evaluating BART. 

This includes new information provided by U.S. Steel related to its Keetac furnaces and Minntac 

fiu·naces 3, 4, and 5 being submitted in a separate petition for administrative reconsideration. 

This information was not available until after the close of the public comment period, and is of 

central relevance to the final rule because it undercuts the assumptions EPA made regarding the 

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status ofLNB technology that formed the basis for EPA's SIP DisapprovaL In this circumstance, 

the CAA mandates reconsideration. 1 

Argument in Support of Cliffs' Petition 

Inf01mation that has become available since Cliffs submitted comments on EPA's 

proposed SIP disapproval refutes EPA's assumptions regarding the technical feasibility of LNBs 

for Cliffs' fumaces. This includes new information fi·om U.S. Steel that burner retrofits at 

Keetac and at Minntac lines 3, 4 and 5 are encountering insurmout1table obstacles to installing 

the LNB technology installed at Minntac lines 6 and 7. A technology is only considered 

"teclmically feasible" under EPA guidelines if it has "been installed and operated for the type of 

source under review under similar conditions/, or "could be applied to the source under review." 

40 CFR 51 App. Y § lV.D. The states appropriately excluded them from further BART analysis 

at the time of their BART determinations, and new infonnation confirms the validity of those 

judgments .. 

I. Significant Distinctions between Furnaces 6 and 7 at Minntac. United Taconite, 

and Tilden Rebut EPA's Technical Feasibility Conclusions for Grate-Kilns 

In arguing that LNBs must be considered technically feasible for all grate-kilns because 

they have been installed on the "same source type" as furnaces 6 and 7 at Mim1tac, EPA 

erroneously assumed that the furnaces were operating under "similar conditions." Since the 

close of the public comment period, Cliffs has been granted access to the U.S. Steel Minntac 

facility and discovered differences between the operating conditions at Minntac and the 

operating conditions at United Taconite and Tilden that reinforce the importance of the required 

case-by-case evaluation of retrofit technologies. U.S. Steel has experienced different operating 

conditions at Keetac and at Minntac's other furnaces as set fmth in their separate petition for 

reconsideration. 

First, the two Minntac fumaces that have installed LNBs (Lines 6 a11d 7) also have small 

LNBs installed in the preheat sections of their furnaces, which are capable of achieving very low 

NO, emission rates (0.1-0.3 lb/MMBtu) with minimal threat to product quality. The preheat 

sections contribute approximately 30 percent of the total heat input to each furnace, which allows 

the Milmtac furnaces to maintain higher NO, rates at their main burners. United Taconite and 

Tilden do not operate preheat burners, and therefore do not have the option of reducing NOx in 

this manner. Instead, United Taconite and Tilden would need to achieve all NOx reductions fr-om 

the main burner. In order to achieve the NOx reductions mandated by EPA in its FIP rule, the 

adjustments to the main burner would require enormous amounts of excess air to cool the flame 

and additional fuel consumption to heat that additional air. This would create higher fuel 

penalties than those experienced at Miimtac, estimated to be 25-4 5 percent for each fiu·nace. See 

Declaration of Eric Wagner (Attachment B). 

1 This new information is also relevant to EPA's related BART FIP rulemaking, published at 78 Fed. Reg. 8706 

(Feb. 6, 20 13). Cliffs has a Petition for Reconsideration of the BART FIP rule also pending before EPA and 

requests that the information contained herein also be considered as part of that reconsideration. 

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Second, the Minntac fumaces process a different type of ore than the furnaces at United 

Taconite and Tilden that reduces Minntac's fuel consumption at lines 6 and 7. Minntac 

processes an ore with a higher magnetite content, which contributes heat to the kiln during 

oxidation (exothermic reaction). United Taconite processes ores with lower magnetite 

concentrations, and Tilden primarily processes hematite ores that do not contribute heat to the 

furnace. As a result, Cliffs' furnaces are configured differently to recapture more heat and to 

efficiently use fuel to maintain furnace temperatures. For this reason, Cliffs' furnaces have 

fewer options for new efficiency improvements to offset the LNB energy penalty than Minntac. 

In addition, Minntac was able to take advantage of ported kilns on its fumaces to help with pellet 

oxidation due to the type of ore that Minntac processes. This reduces the amount of extra heat 

the furnace must produce to oxidize the pellets. United Taconite and Tilden cannot gain this 

same benefit from installing ported kilns because of the types of ore they process. For these 

reasons, Metso has determined that the unacceptable energy penalty associated with LNB 

installation at United Taconite and Tilden cannot be offset by additional efficiency 

improvements as occurred at Minntac. See Declaration of Eric Wagner (Attachment B). 

As outlined in its own Petition for Reconsideration, U.S. Steel similarly has encountered 

technical feasibility issues while attempting to apply the LNB teclmology installed at Minntac 

Lines 6 and 7 to other fumaces that do not operate ported kilns and that have different burner 

configurations and process throughputs. U.S. Steel anticipates significantly higher costs and fuel 

penalties at these units, and has raised similar concerns over pellet quality. 

These factors demonstrate that United Taconite and Tilden are not being operated nnder 

"similar conditions" as the furnaces at Minntac. It was therefore arbitrary for EPA to determine 

that LNBs were automatically "technically feasible" for all grate-kiln furnaces. EPA has an 

obligation to reconsider its SIP Disapproval to take into account the new infom1ation presented 

here that undermines the premise for its action. 

2. Cliffs is Unable to Locate Commerci;illy Available LNBs for its Grate-Kiln and 

Straight-Grate Fumaces 

EPA erroneously assumed in its SIP Disapproval that LNBs had either been "installed 

and operated for the type of source under review under similar conditions," or "could be applied 

to the source under review." 40 CFR 51 App. Y § IV.D. Cliffs has explained above that LNBs 

have never been installed on sources similar to Cliffs' furnaces "under similar conditions," and 

therefore EPA can only find that LNBs are technically feasible if they "could be applied" to 

Cliffs furnaces. This requires a finding that the LNBs are both "commercially available" and 

"applicable" to Cliffs' furnaces. Cliffs' extensive work to locate LNBs suitable for installation 

in its furnaces, including substantial new effOtt since the end of EPA's connnent period, 

demonstrates that neither is tme. 

Cliffs has now spent 18 months investigating LNB options for its three grate-kiln and five 

straight-grate taconite furnaces. See Declaration of Peter Suardini (Attachment A). Cliffs 

retained Metso Minerals, an engineering company with broad experience at taconite furnaces, to 

assist in this investigation. Id Contrary to EPA's assumption, Metso reports that there are no 

off-the-shelf, commercially available LNB options for Cliffs' furnaces that will not have 

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unacceptable energy penalties or create product quality concerns. The manufacturer ofLNBs for 

Minntac's grate-kiln taconite furnaces, Coen, confinned that it could not guarantee that its 

burners would achieve the NO, reductions mandated by EPA without affecting pellet quality. I d. 

Metso's analysis ofCoen's high stoich LNB technology concluded that it will result in an 

unworkable 25-45% energy penalty when applied to United and Tilden. See Declaration of Eric 

Wagner (Attachment B). Burnet manufacturers have expressed interest in working with Cliffs to 

develop low NO, combustion technology, but each requires fi1rnace-specific development of a 

technology that requires pilot testing to determine if pellet quality can be assured at a reduced 

NO, rate. This is a clear indication that LNB is in the early stages of development for taconite 

furnaces and it does not qualify as an available retrofit technology. 

After diligent research and substantial expense over more than a year, Cliffs has been 

unable to identify a single burner on the open market that can be installed in its straight-grate 

furnaces. Declaration of Eric Wagner (Attachment B); Declaration of Peter Suardini 

(Attachment A). The states were correct in their assessment that the LNB technology being pilot 

tested in Cleveland Ohio without introducing pellets was too nascent to be considered BART for 

straight-grate taconite furnaces. Despite EPA's optimism over the usc ofLNB technology in 

these applications, reality has demonstrated that this technology is not yet developed to the point 

that it is both commercially available and applicable to Cliffs' fi1rnaces. · 

EPA may not ignore hard evidence that its assumptions regarding the teclmical feasibility 

of LNBs were incorrect. EPA must address information that undermines its analysis. 78 Fed. 

Reg. at 59829. EPA's technical feasibility assumptions go to the heart of its SIP Disapproval, 

making this an issue of central relevance to the final rule. 

Conclusion 

Thank you for your consideration of the important issues identified in this petition. The 

information that became available after the close of the public comment period regnrding the 

status ofLNB technology for taconite furnaces demonstrates beyond doubt that EPA's rationale 

for the SIP Disapproval was based on enoneous assumptions. In this circumstance, The Clean 

Air Act requires EPA to reconsider the SIP Disapproval and issue a decision that is in accord 

with the evidence before the Agency. 

sm,;~c£~ 

tliel E. Long 

Cliffs Natural Resources Inc. 

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DECLARATION OF PETER SUARDINI 

I, Peter Suardini, declare as follows: 

1. My name is Peter Suardini, I am a Senior Staff Pyrometallurgical Engineer for Cliffs 

Technology Group (CTG), a division of Cliffs Natural Resources Inc. (Cliffs). 

2. I earned Bachelor and Master of Science Degrees in Metallurgical Engineering from 

Michigan Technological University, in the early 1980's. 

3. J have over 30 years of experience in design, installation, commissioning, & operations of 

various mineral and thermal processing systems, at industrial coal and iron ore facilities. 

4. I have been employed by Cliffs for 18 years, and have spent the past 15 years focused 

principally on optimizing and upgrading Cliffs' iron ore pelletizing furnaces, including a 

number of projects related to Cliffs' grate-kiln burner systems (at both Tilden and United 

Taconite). 

5. Over the last 18 months, Cliffs has been conducting "case studies" (led by myself 

and others), to evaluate the feasibility of Low NOx Burner (LNB) installations at 

each of Cliffs' three grate-kiln and five straight-grate indurating furnaces subject to 

BART. Cliffs also retained Metso Minerals ("Metso"), one of the world's foremost 

experts in taconite furnaces, to assist in these investigations. 

6. Looking for Available LNB Technologies: Since June of2012, Cliffs has invested 

thousands of hours and more than $700,000 evaluating available LNB technol~gies 

for its taconite furnaces. Despite this investment, neither Cliffs nor Metso has 

located a commercially available LNB that can be installed at any of Cliffs' gratekiln or straight-grate furnaces without substantial energy penalties (25-45% when 

burning natural gas), retrofit costs, or potential significant pellet quality impacts. 

7. LNB for Straight-Grate Furnaces: It is public knowledge that Fives is developing a 

natural gas based, LNB system for use at the new Essar straight-grate furnace. This LNB 

system has not yet been installed or proven at any industrial iron ore pelletizing 

operation. The Fives' LNB system has merely been tested using a single small natural gas 

burner, on a pilot-test rig at Fives' laboratory facilities. The pilot burner is much smaller 

scale than those required in Cliffs' existing straight-grate operations. The pilot testing 
also was not done in the presence of any iron ore pellets, let alone on a continuously 

operating iron ore pelletizing furnace. 

8. LNB for Cliffs Straight-Grate Retrofits: Based on a conceptual engineering "case study" 

(funded by Cliffs), Metso and Fives estimated that the fuel penalty associated with 

implementing the proposed Fives LNB system at Hibbing Taconite (Hibtac) L-1 furnace 

would be 16.5% (for natural gas burning). Based on the lack of any detailed furnace 

modeling, Metso was only willing to guarantee that the furnace retrofit fuel penalty will 

not exceed 25%, for permitting purposes. The proposed Fives LNB system will also 

require a new electrostatic precipitator (ESP) to clean the recirculated combustion air to 

the burners. The new ESP will have to be housed in a separate new building, since it will 

not fit within the existing footprint of the plant. 

9. LNB for Grate-Kiln Furnaces: It is also public knowledge that USX Minntac purchased 

and installed Coen prototype Low NOx kiln burners (LNB) on their L-7 and L-6 gratekiln furnaces. Minntac' s LNB reports to the MPCA report to hl}ve partially-to-completely 

mitigated the fuel penalty (initially estimated at about I 0% for natural gas burning), by 

increasing waste gas airflows, along with other energy optimization initiatives (including 

some cooler modification projects). However, unlike Minntac, neither Tilden nor United 

Taconite (Utac) use preheat burners, and the kilns are not ported (like the Minntac L-6 

and L-7 kilns). This discrepancy is mostly due to the differences in furnace designs and 

the type of pellet products being produced. In summary, preheat burners and ported kilns 

are not applicable techuologies for Cliffs' grate-kiln furnace operations at Tilden and 

Utac. In Cliffs' furnaces, it is more energy efficient to have all the fuel and heat required 

for the process to be provided by the kiln burners, and to have all the ambient air required 

for pellet oxidation and initial cooling to be provided in the primary cooling section. 

10. LNB for Cliffs Grate-Kiln Retrofits: Based on conceptual modeling "case studies" 

(funded by Cliffs), Metso estimated that the "unmitigated" fuel penalty associated with 

implementing a Coen prototype Low NOx "gas" burner, on Tilden L-1 and Utac L-2 

kilns is approximately 40-45%. Further conceptual modeling by Metso also indicated that 

even significant increases in process fan airflows (resulting in dramatic changes in 

process temperatures and the overall process heat balance), will only "partially" mitigate 

the fuel penalty for the Tilden and Utac furnaces (the fuel penalties are still estimated to 
be in the 25-37% range). Due to fundamental difference in the Tilden and Utac furnace 

designs (compared to Minntac L-6 and L-7), the fuel penalty of the Coen LNB will be 

much greater and more difficult to mitigate in the Cliffs' furnaces. 

11. At the present time, despite the significant residual negative impacts to the process 

energy efficiency, heat balance and other retrofit impact concerns, neither Fives or Coen 

have provided written guarantees that the LNB systems they propose to install on Cliffs' 

straight-grate and grate-kiln furnaces, will meet a NOx limit of <1.2#/MMBtu. 

12. Similar to Minntac, Cliffs and Metso anticipate that a number of the process fan wheels 

and/or the associated motors will also need to be upgraded and/or replaced to facilitate 

the higher airflows required in the grate-kiln process. However, unlike Minntac, the 

Tilden and/or Utac furnaces will likely also require much more expensive ductwork, 

structural steel, power distribution, and dust collector "expansion" projects. 

13. The burner( s) and furnace configuration are the "heart" of the indurating process, 

controlling the heat, time, and temperature profile, as well as all chemical reactions in the 

furnace; all of which control resultant pellet quality. 

14. Cliffs has completed Phase I conceptual LNB engineering "case studies" with both Fives 

and Coen, for the first Cliffs straight-grate and grate-kiln furnaces (Hibtac L-1, Tilden L1, and Utac L-2). In all "case studies", Coen and Fives will not and cannot take the 

responsibility for the adverse impacts to Cliffs furnaces caused by their proposed 

prototype LNB systems (ie., fuel penalties, pellet quality/throughput impacts, 

downtime/derating costs, or other environmental issues). They defer to Metso and Cliffs 

to determine and mitigate those impacts. Equally concerning, is Metso's present inability 

to quantify those impacts, and/or guarantee that Cliffs operations will still be able to 

satisfy our customer's pellet quality specifications and production requirements in the 

merchant supplier market where Cliffs operates. 

15. As such, the NOx reductions and energy efficiency improvements associated with 

these aspects of the Minntac furnaces cannot be replicated in the same way at Cliffs. 

Simply stated, the Minntac furnaces are materially different from the furnaces at 

United Taconite and Tilden. 
I declare (or certify, verify, or state) under penalty of perjury under the laws of the United 

States of America that the foregoing is true and correct. 

Executed November 26, 2013 

By: 

Peter S uardini 

Senior S!affPyrometallurgical Engineer 

Cliffs Natural Resources 
DECLARATION OF ERIC WAGNER 

l, Eric Wagner, declare as follows: 

1. ·My name is Eric Wagner. l am the Manager of Process Engineering for 

Metso Minerals Pyro Division ("Metso"). 

2. Metso is a global expert in the design of iron ore pelletizing furnaces, having 

designed over 53 grate-kiln and 42 straight-grate furnace systems since its predecessor, 

Allis-Chalmers, first developed the pelletizing technology in the 1950s. 

3. l have twenty five (25) years of experience in design, moditlcation, analysis, 

and commissioning of varied thermal processing systems including iron ore pelletizing 

(both Grate Kiln and Straight Grate Technology), lime calcining, coke calcining, and other 

minerals processes. During those 25 years I have evaluated the majority of the pelletizing 

furnaces in the United States and I am uniquely qualified to compare the properties of these 

furnaces. 

4. Metso has obtained new information regarding the unique characterisiics of 

the U.S. Steel Minntac furnaces ( 6 and 7) related to the generation and control of NOx 

emissions using LNB technology. Some of the information contained herein was disclosed 

to me during a November 22, 2013 teleconference with Cliffs engineering personnel 

whereby information was revealed to Cliffs during reciprocal visits to Cliffs' Tilden site 

and USS Minntac on July 10, 2013 and August 27, 2013, respectively. Additionally, new 

information was also recently obtained from engineering assessments performed by Coen 

and Met~o Fives dated September 19, 2013 and June 4, 2013. This information reveals 

significant differences between these Minntac furnaces and other Grate Kiln furnaces 

operated by Cliffs Natural Resources at United Taconite and Tilden that are relevant to the 

formaiion and control of NO, emissions. 

5. Minntac furnaces 6 and 7 operate preheat burners in addition to the large 

kiln burner. United Taconite and Tilden use a single kiln burner. Approximately 1/3 ofthe 

heat input from fuel for the Minntac furnaces is delivered at the preheat burners. These 
smaller preheat burners can achieve very low NO, rates (0.1-0.3 lb/MMBtu) due to a more 

favorable NO, reduction combustion environment in the preheat zone as compared to the 

firing end of the kiln. The lower NOx generation of preheat burners allows the kiln burner 

to produce NO, levels above the plant overall NO, limits and still maintain overall NO, 

limits. An example of how this is achieved follows: (0.33 fraction of heat from preheat 

burners) multiplied by (0.1 preheat burners Jb/MMBTU NOx rate) plus (0.67 fraction of 

heat from kiln burner) multiplied by (1.75 kiln burner lb/MBTU NOx rate) equals (1.2 

lb/MMBTU overall NOx rate). The following calculations use the min and max NOx rates 

for preheat burner. (0.33 x 0.1) + (0.67 x 1.75) = 1.2 and (0.33 x 0.3) + (0.67 x 1.64) = 1.2. 

From these calculations it can be shown that the kiln burner can produce 37% (1.64/1.2) to 

45% (1.75/1.2) more NOx emissions and still maintain overall NOx limits. United Taconite 

and Tilden use only a single kiln burner, so they do not have the ability to shift NO, 

reductions to more easily achieved NOx reduction with preheat burners. 

6. Minntac furnaces 6 and 7 process high magnetite ore that contributes heat to 

the kiln when oxidized. Tilden's ores are primarily hematite, which is not a source of heat 

for the kilns. United processes ores with a lower concentration of magnetite than Minntac. 

Therefore, Tilden's furnaces and United's furnaces must add more fuel to achieve final 

product requirements than Minntac. It follows that Cliffs has invested in fuel efficiency 

improvements to minimize this differential cost. Metso has determined that the energy 

penalty associated with heating the additional cool air introduced with the LNB technology 

in use at Minntac cannot be offset by additional energy efficiency improvements at United 

and Tilden. Those energy penalties are predicted to remain 25-45% for Cliffs' furnaces. 

7. Minntac furnaces 6 and 7 use ported kilns to maximize the benefit of their 

high-magnetite ore bodies. Ported kilns allow the introduction of additional air directly to 

the kilns where it helps oxidize the high magnetite ore that Mi1mtac processes. United and 

Tilden do not use ported kilns because porting will not produce significant benefits for the 

type of ore they process. Ported kilns significantly change the heat balance of the furnace 
making it difficult to generalize from Minntac' s experience at Tilden and United. 

8. Mitmtac furnaces 6 and 7 are also Ullique because they produce high flux 

magnetite pellets. By contrast, United produces primarily standard (low-flux) magnetite 

pellets. Tilden produces high flux hematite pellets. These furnaces are Ulliquely designed 

with heat sources and air flow to produce a quality pellet for their specitlc product. 

Retrofitting a furnace with the Coen-type LNB burner introduces more air, requires more 

fuel, and at different locations. As a result, the LNB retrofit must be evaluated in the 

context of the Ullique furnace design for that specific pellet product from that specific ore 

type. The Minntac experience cannot be generalized to other furnaces. Each furnace is a 

unique design project to determine if that type of burner can work without unacceptable 

pellet quality and energy penalty problems. 

9. Current LNB burner technology for Tilden and United Taconite require 

additional air to reduce burner !lame temperature. The increased air at the kiln burner will 

through to the grate drying section. The increased airflow through the drying section will 

result in an increased pressure drop across the greenballs. Greenballs are defined as raw 

feed to indurating furnace. Undried greenballs have minimal strength, the higher bed 

pressure will deform the greenbal!s. Deformed pellets lower bed permeability causing 

restricted air flow, poor pellet heating and ultimately reduced pellet quality. In addition, 

spherical pellets are required for blast furnace operation where the pellets are used as raw 

feed for iron making. The increased air flow in drying section will also increase green ball 

drying rate. Drying greenballs too quickly, will rapidly release water vapor, ie steam 

explosion, and cause pellet breakage. Rupture pellets lead to decreased in production rate 

due to generation of Ulluseable fines and reduced pellet quality. In order to maintain pellet 

quality, the overall dryer section air flow and drying rate must be limited. Limiting is 

accomplished by reducing the amoUJlt of recovered heat from cooler. This unrecovered 

heat must be replaced with additional burner fuel, hence compoUllding fuel requirements. 

10. For Straight Grate furnaces, Low NOx burner (LNB) technology has been 
pilot tested by Fives North America in a prototype combustion chamber in Cleveland, Ohio, 

but LNB technology has not been installed to date on any Straight Grate furnace that is 

producing iron ore pellets. 

11. The Coen burners installed at the Grate Kiln furnaces at U. S. Steel's 

Minntac facility cannot be used to retrofit Straight Grate furnaces because the two furnace 

designs are fundamentally different with regard to burner use and heat balance. 

12. Metso has continued to survey burner manufacturers with relevant 

experience in search of available teclmology for Straight Grate furnaces in recent months. 

Metso has concluded that no Low NO, techr1ology has been demonstrated commercially 

available for this type of furnace. 

I declare (or certifY, verity, or state) under penalty of perjury under the laws of the United 

States of America that the foregoing is true and correct. 

Executed November 26, 2013 

Eric Wagner 

Manager of Process Engineering 

Metso Minerals Pyro Division