Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 1 of 13 

## Narrative Response to Items Listed in Appendix C of EPA Request for
Information Addressed to United Taconite Received April 6 , 2012

Items from Appendix C are restated below in italic print with United Taconite ’s response directly following each.

1. Provide process flow diagrams for both the taconite iron ore mining and the taconite pellet manufacturing processes. Include in the description, at a minimum, information on the following: mining operations, ore transfer and storage, course ore crushing, fine ore crushing, ore classification screens, ore storage bins, grinding rod/ball mills, separation, thickeners, balling drums/pellet formation, indurating furnace, pellet cooling and storage, and the process boilers. Include a detailed narrative proces s description and photographs to explain the indurating furnace process (separately for each furnace). For each photograph, provide a coded diagram/map to clearly identify the location of the image in the photograph. Photographs must correspond to each o f the process stages described.

Process D escription: Taconite is mined from the Thunderbird Mine. The mining operations include the removal of overburden material, removal of waste rock material, and mining of taconite ore. The taconite
is loaded onto tr ucks, hauled to the crusher , and crushed at the primary and secondary stages of crushing

. Mined ore truck dumping, primary and secondary crushing, and rail car loading emissions are controlled by baghouses. Crushed rocked is conveyed to a domed storage f acility and then loaded onto rail cars and is transported off

- site 1

.

Crude ore is transported by rail to the Fairlane Plant using an independently owned contractor

. Crushed ore is unloaded in a covered building. The ore is then transferred by a cover ed conveyor to the fines crusher building where it is immediately crushed at the third stage crushers or sent to the coarse ore surge stock pile. The coarse ore surge pile is used to store ore between train shipments or during times when the crusher is dow n.

Ore is returned from the coarse ore surge pile and fed into one of the five third

- stage crushers. The oversize material is conveyed to one of eight fourth

- stage crushers. Undersize material is transferred to the fine ore surge building. Oversized material is recirculated to the fourth stage
crushers.

Five concentrator lines receive ore from the fine ore surge building. Ore is ground with rod mills
and ball mills. Magnetic separators remove magnetite ore from the tailings. Low

- magneti c coarse tailings are transported by truck for use as construction material for tailings basin
sidewalls. Fine tailings are pumped in a slurry form to the tailings basin. Processes performed in the concentrator are wet operations. Concentrate is piped a s a slurry to the pelletizing plant. The slurry is dewatered with filters and additives are introduced. Green pellets are produced in balling drums and conveyed to one of two travelling grate kilns. Grate feed, grate discharge, kiln induration, and kiln cooler emissions are controlled with wet scrubbers.

1 13700011

- 001 Air Permit

– Mine (see Folder #1)Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 2 of 13 Fired pellets are conveyed to pellet storage silos. Pellets are loaded into rail cars and transported from the facility via an independent rail contractor. Particulate emissions from the pellets are controlled with wet scrubbers and dust suppressants. 2

Detailed D escription of Induration Process: As stated above, United Taconite owns and operates two travelling grate kilns. The first
indu rating furnace, referred to as Line 1

, consists of a travell ing grate, kiln, and annular cooler.
The t raveling grate is a metal casting conveyor which carries green pellets through two cross flow processing zones for drying and preheating the green balls. The grate is 12’2” wide and 112’7” long. The drying sectio n has two downdraft zones. The first drying section employs air from the preheat stage (500

- 650 °F), the second section utilizes second stage cooling air (known as recoup) at 1000

- 1500 °F. Air movement in the drying section is accomplished by one 3000 HP
induced draft fan. The green pellets then travel through the preheat section of the grate , which
is powered by two 900 HP induced draft fans.

The grate empties into an Allis

- Chalmers kiln, 18’6” in diameter and 120’ long (27,300 ft 3 working volume). Air enters the kiln from the first stage of cooling (2000

- 2200 °F)

, and is heated

to 2400 °F by a tri

- fuel burner. The kiln is supplied with two emergency drives, one electric powered, the other gas powered.

The pellets travel through the kiln into a re fractory lined cooler (50’ D ia. x 7’ W)

, and are leveled to a 30” bed depth by a stationary screening wall. As the annulus cooler rotates, the bed of pellets pass through two updraft cooling zones. In the primary cooling zone, a forced draft fan pushes outside air through the bed of pellets and into the linear flow duct to the kiln. The primary cooling zone is powered by a 700 HP f orced draft fan. In secondary cooling, another fan pushes air through the pellets to continue the cooling process. This air is directed to heat recuperation ducts and is delivered to the drying zone of the grate (recoup)

.

The second indura ting furnace is referred to as Line 2. Line 2 is operationally similar to Li ne 1, but is much larger. The travelling grate is 18’7” wide and 130’8” long. The drying section has two downdraft zones that operate at the same temperatures as L ine 1. Air movement in the drying section is accomplished by two 3000 HP induced draft fans , and utilizes air from the preheat stage and from the second stage cooling air (recoup)

. Next, the green pellets travel through preheat section of the grate, which is powered by two 2000 HP induced draft fans.

The green pellets leave the grate an d enter an Allis

- Chalmers kiln, 22’6” in dia meter and 130’ long (43,100 ft 3 working volume)

. Air enters the kiln from the first stage of cooling at 2000

- 22 0 0
°F

, and is heated to 2400 °F by multi

- fuel burners. Line 2 has two burners located adjacent to
one another. One burner is used for burning natural gas and fuel oil , the other is for burning
solid fuel.

The pellets travel through the kiln and empty into an annular cooler (54’ D ia. x 10’2”W)

. The pellets are leveled to a 36” bed depth by a stationary screening wall. Line 2 also has two cooling

zones. In the primary cooling zone, a 2500 HP forced draft fan pushes air through the pellet
bed. This air is channeled through the linear flow duc t into the kiln. The secondary cooling zone

2 13700113

- 005 Air Permit

- Plant (see Folder #1)Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 3 of 13 is powered by another 2500 HP fan

, which pushes are through the pellet bed. This air is directed to heat recuperation ducting and is delivered to the drying zone of the grate (recoup)

. 3

Process flow diagrams are provided in Folde r #1 in a subfolder named “ Process Diagrams ”

. While at United Taconite on April 19, 2012, EPA took photos and videos as part of their inspection. As discussed with Molly DeSalle during the EPA’s site inspection, United Taconite
has n ot provided additional photos.

Information that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite . Scott Gischia of Cliffs Natural Resources and counsel were al so consulted

.

2. For the time period January 1, 2010 to December 31, 2011, provide manufacturing specification and operating data to demonstrate operating parameters for each of the facility’s indurating furnaces. Operating parameters and data must inc lude, at a minimum: flue gas composition, entrance air temperature, exit air temperature, preheat zone temperature, burner temperature, pellet residence time, and air flow rate.

As stated in the March 8, 2012 Regional Haze Supplemental State Implementati on Plan for United Taconite (excerpt located under Folder #2

– “ UTAC Pages from Supplemental Regional

Haze SIP

- March 2012 Citizen's Board.pdf ” ), “ The facility has two indurating Allis

- Chalmers furnaces. Line 1 is the smaller of the two, with a rated throughput of 280 tons of pellets per hour and a heat input of 190 MMBtu per hour of natural gas. The newer line, Line 2, is rated at 672 tons per hour with a heat input from natural gas, coal, pe troleum coke, and other fuels of 400 MMBtu per hour.” It s hould be noted that post August 2011, Line 1 ’s specifications change

to reflect a current operating heat input from natural gas, coal, petroleum coke, and other fuels of 180 MMBtu per hour. The manufacturing specifications for the burners for the furnace a re located in Folder #2 , in a subfolder named “Burner Manufacturing Specifications”

.

Folder #2 contains a summary of the furnace specifications (Summary Table Furnace Line Specs.xlsx). Note that the furnace summary table is a compilation of what Unite d Taconite believes to be the most accurate depiction of it s current furnace operations. This is based upon
historic documents belonging to owners prior to Cliffs’ purchase of United Taconite in 2003 , as well as plant knowledge

. United has no way of veri fying the completeness and/or veracity of documents which pre

- dated its ownership of the facility. The plant operating data is also located under Folder #2 ( Operating Data .xlsx ) . A diagram has been provided depicting where the operating temperatures are recorded in the process (see the document titled “Process Diagram Temp Explanation .doc” ). Please note that no instrumentation exists in the drying section on Line 1 to record temperatures, which is why this information is not included in the
enclosed work book.

Information that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also
consulted

.

3 Equipment Information Induration UnitsResponse to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 4 of 13 3. For the time period January 1, 2007 to December 31, 2011, provide records of the natural gas used by each specific indurating furnace at the facility.

The natural gas usage history is only available from January 18, 2007 to the present and has been provided as such (this data was not captured in United Taconite’s data collection system prior this date)

. Natural gas usage is located in an unlocked spreadsheet in F older #3 (see “Natural Gas Usage.xlsx”)

.

Information that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also
consulted

.

4. For the time period January 1, 2007 to December 31, 2011, provide d ocumentation of the average sulfur content for coal used by each specific indurating furnace at the facility.

One coal sample is taken daily Monday through Friday when coal is being utilized. As required on pages A

- 51 and A

- 58 in United Taconite’s Air E missions P ermit 13700113

- 005 , “the Permittee shall collect a solid fuel sample each weekday from the pulverized fuel pipe. The Permittee shall form a weekly composite of all samples coll ected in a given calendar week” (see Folder #4

– “Pages from 13700113

- 005 Air Permit

– Fuel Sampling.pdf”).

From January 1, 2007 through August 26, 2011, Line 2 was the only furnace line capable of utilizing coal. After August 26, 2011, both furnace Lines 1 and 2 were capable of utilizing coal after receiving a co nstruction permit for this additional fuel flexibility (known as the Green Production Project) . Folder #4 contains a spreadsheet titled “Weekly Coal Analysis .xlsx ” that summarizes the sulfur values recorded from the weekly samples from each furnace l ine

, as appropriate

.

Information that was used or considered in preparation of this response was provided by Candice Maxwell and Lisa
Weidemann of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also consulted

.

5. Provide copies of all stack tests conducted on any emissions unit for any reason, and include all test runs, even if a full test series was not completed. Identify the emissions unit; specify the date of the test, test method used, and the filter temperature during the time of the test, if applicable. Provide all calculations relative to the stack test, and provide copies of the full test report, including the section describing the process parameters and production or processing rates at the time of the test, as well as copies of any reports of visible emission observations conducted during each test. For each test during which the source was not operating at maximum design capacity, provide an explanation why production was limited.

Page 2 of EPA’s request letter s tates that , “We are requesting information on the facility’s furnaces and other nitrogen oxide (NO
x ) and sulfur dioxide (SO 2 ) emitting units at the facility.” As such, the response to this question has been provided to be consistent with that request, and
focuses on SO 2 and NO
x stack test information from the facility.Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 5 of 13 All stack tests conducted that measured NO
x or SO 2 are located in F older #5 and are summarized in the spreadsheet named “Summary of Stack Test Reports .xlsx ” . Any calculations

, process rates, and testing exceptions will be noted within the test reports. Page A

- 4 of United Taconite’s

A ir E missions P ermit 13700113

- 005 specifies tonnage requirements for performance testing on
each furnace ( see “Pages from 13700113

- 005 Air Permit

– Stack Test Process Rates.pdf” in Folder #5)

. All included performance tests were conducted at or above permit specifications.

Information that was used or considered in preparation of this response was provided by Candice Maxwell and Lisa
Weidemann of United Taconite

, and Paul Taylor of Barr Engineering. Scott Gischia of Cliffs Natural Resources and
counsel were also consulted

.

6. Provide an electronic Excel workbook with the complete nitrogen oxide (NOx) and sulfur dioxide (SO 2 ) facility

- wide potential to emit calculations. Include in the response a written description of how each column in the Excel workbook is generated.

In August 2010, United Taconite receive d approval for an amendment to its air permit (Green Production Project) . As par t of the permit amendment, United Taconite agreed to emission
reductions for NO
x and SO 2 . The potential to emit calculations in the workbook located under

F older #6 reflect the more restrictive limits taken by United Taconite as part of that amendment (se e “NOx and SO2 PTE.xlsx”)

.

Information that was used or considered in preparation of this response was provided by Candice Maxwell of United
Taconite and Paul Taylor of Barr Engineering . Scott Gischia of Cliffs Natural Resources and counsel were also

con sulted

.

7

- 9. The following information is provided as common background for Questions 7, 8

, and 9 of the Request. Additional information specific to each Question is further included in each section as appropriate.

As indicated in EPA's Section 114 Re quest, the BART Reports were developed in 2006 using control technology that was considered available and technically feasible at that time. In preparing the BART Report referenced in EPA's Questions 7 through 9, two guidance documents
were relied on to e stablish the process and methodology. These were:

1. MPCA's 2003 "Guidance for Facilities Conducting a BART Analysis .pdf "; and 2. EPA's "Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations .pdf ", Jul y 6, 2005, specifically pages 391614 to 39170 of the Federal Register.

The document from MPCA entitled Guidance for Facilities Conducting a BART Analysis provided the basis and requirements for the BART reviews. This document specifies that the Taconit e MACT is to be considered equivalent to BART for particulate sources subject to both rules. EPA's Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations in combination with MPCA's guidance provided the five step BART review process, which was followed for the BART analysis in the BART Reports

.Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 6 of 13 In addition to these guidance documents, the BART Report relied on Section 6 of MPCA's 2003 "Potential Impacts of the Federal Regional Haze and Best Available Retrofit Technology Rules on the Taconite Industry in Minnesota .pdf ." This document established the control technology available and technically feasible for the taconite industry in Minnesota. It was developed through a stakeholder process, which included membe rs of MPCA, representatives of the Minnesota taconite plants, representatives of Indian tribes and NGO's as well as other
stakeholders.

Cliff's BART Reports also relied on the information contained in its Northshore Facility's permit
for its 2005 Line 5 R eactivation Project (see “Furnace 5 Restart Vol I BACT.pdf”) . This project required Best Available Control Technology (BACT) analysis for control of nitrogen oxides and sulfur dioxide emissions as part of its PSD permit. This BACT analysis is considered more rigorous than BART analysis. Each of the background documents referenced within this section is located in the Folder Supporting Documents #7

- 9

. Also included in this folder is an e

- mail (with attachments) that shared with MPCA the potential NO
x and SO 2 technologies defined as available and applicable for further assessment in the facility

- specific BART analyses (see “9May2006 Barr to MPCA SOx NOx Control Technologies.pdf”)

.

Information that was used or considered in preparation of this response was provided by Candice Maxwell of United Taconite, and George Pruchnofski, Beth Havlik, Teresa Kinder, Erik Boleman, and Jack Kennedy of Barr Engineering.
Scott Gischia of Cliffs Nat ural Resources and counsel were also consulted

.

7. The facility’s Best Available Retrofit Technology report, available on the Minnesota Pollution Control Agency Regional Haze website (“BART report”), dis cusses the low efficiency o f the facility’s wet sc rubbers for SO 2 . Provide all documentation, including reports and studies, to
determine the current SO 2 efficiency of all water scrubbers at the facility. Additionally, provide all documents, including reports and studies, completed for the technical feasibility of efficiency upgrades for each scrubber.

The control efficiency of the scrubbers at United Taconite was determined based on mass
balance studies included under Folder #7, in a subfolder named “Mass Balance Studies”. In addition, a study by M PCA entitled “Evaluation of Minnesota Taconite Wet Scrubbers at Minntac, Keewatin Taconite, Hibbing Taconite, and United Taconite .pdf ” (see Folder #7) was referenced regarding scrubber efficiency, page 6 and the ability to improve the performance of
existi ng scrubbers for SO 2 removal , pages 11

- 14 , along with input from Hal Taylor of STS Consultants as provided in an e

- mail from Jack Kennedy (Barr) dated July 10, 2006 (see “ STS
Consultant Email

- Cost to Increase Scrubber Efficiency .pdf”

– Folder #7)

. The EPA CUECOST Manual was relied upon to determine the relative cost of retrofitting existing facilities compared
to new facilities (see “CueCost Workbook.pdf” located in Folder #7)

. In addition, United Taconite submitted a revised BART analysis for an SO 2 w et scrubber to MPCA on October 25, 2007. The revised analysis is included in Folder #7 (“Revised BART Analysis Submittal

– Line 2 SO2 control.pdf”)

. E

- mail correspondence supporting the revised SO2 analysis is located in a subfolder labeled “E

- mail Corre spondence” located in Folder #7.

United Taconite c onducted a feasibility study on installation of a Dry ESP. This study was conducted as part of the “Green Production P roject ” that was permitted in August 2010.Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 7 of 13 Emission reductions were agreed to, allowi ng the permit to move forward without additional control technologies. The feasibility study is also included in Folder #7 (see “UTAC Dry ESP Feasibility Study_01

- 30

- 09.pdf”)

.

Information that was used or considered in preparation of this response was pr ovided by Candice Maxwell of United
Taconite

, and George Pruchnofski, Beth Havlik, Jack Kennedy, Erik Boleman, and Teresa Kinder of Barr Engineering.
Scott Gischia of Cliffs Natural Resources and counsel were also consulted

.

8. The BART report discusses the technical feasibility of low NOx burners and a variety of selective catalytic reduction (SCRs) systems. Provide all documentation, including reports and studies, to determine the technical feasibility of low NOx burners and S CRs at the facility’s indurating furnaces.

Low NO x Burners: See “Potential Impact of Federal Regional Haze and Best Available Retrofit Technology Rule on the Taconite Industry in Minnesota .pdf ”, September 30, 2003 pages 45 and

60

– 62 (see Folder Support ing Documents #7

- 9) . In addition, as described in the “ 2006 United
Taconite BART Analysis.pdf ” (see Folder #13) , page 42, if l ow NO x burners were to be applied in the indurating zone of the furnace, the reduced flame temperatures associated with Low NO x burners would adversely affect taconite pellet product quality

. Low NO x burners have not been applied to the indurating zone of any grate

- kiln taconite furnace. Therefore, t his option is not
viable.

SCR: See budgetary estimate from Vogt Power dated Oc tober 28, 2005 (see Folder #8

– “ Vogt Vendor Budget Estimate (redacted).pdf ” ) , and “ Potential Impacts of the Federal Regional Haze and Best Available Retrofit Technology Rules on the Taconite Industry in Minnesota .pdf” , page 46 (see Folder Supporting Docum ents #7

- 9)

.

The availability and technical feasibility of both low NO
x burners and SCR were discussed as presented in the “ Agenda CCI BART Issues Meeting 08

- 09

- 06.pdf ” document, located in Folder

#8.

Minor corrections were made to United Taconite’s cost estimates. These corrections are captured in an e

- mail titled “ 1.31.07.Jason Aagenes to Mary Jean Fenske.with attachment .pdf” (see Folder #8).

Information that was used or considered in preparation of this response was provided by Candice Maxwell of Uni ted
Taconite

, and George Pruchnofski, Beth Havlik, Jack Kennedy, Erik Boleman, and Teresa Kinder of Barr Engineering.
Scott Gischia of Cliffs Natural Resources and counsel were also consulted

.

9. The BART report discusses the technical feasibility of overfire air and induced flue gas technology. Provide all documentation, including reports and studies, to determine the technical feasibility of overfire air and induced flue gas technology at the facility’s indurating furnaces.

Overfire air and induced flue gas technology: See Northshore Line 5 Restart BACT report (“Furnace 5 Restart Vol I BACT.pdf” in Folder Support Documents #7

- 9) , page A

- 5

- 33, and Metso representative e

- mail dated July 18, 2006 (see Folder #9

– “Metso OFA Email .pdf” )

.Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 8 of 13 Information that was used or considered in preparation of this response was provided by Candice Maxwell of United
Taconite

, and George Pruchnofski, Beth Havlik, Jack Kennedy, Erik Boleman, and Teresa Kinder of Barr Engineering.
Scott Gischia of Cliffs Natural Resourc es and counsel were also consulted

.

10. Identify the manufacturer, including contact information, for all low NOx burners, SCR, scrubber, overfire air, and induced flue gas technologies considered technically feasible for use at the facility.

Please se e the attached document entitled “Manufacturers contact info .xlsx ” found in F older

#10

.

Information that was used or considered in preparation of this response was provided by Candice Maxwell of United
Taconite

, and George Pruchnofski, Beth Havlik , Jack Kennedy, Erik Boleman, and Teresa Kinder of Barr Engineering.
Scott Gischia of Cliffs Natural Resources and counsel were also consulted

.

11. For the time period January 1, 2002, to the date of receipt of this letter, provide all documentation, i ncluding engineering studies or mass balance studies, conducted to determine emissions of NOx from each waste

- gas stack at all indurating furnaces at the facility.

United Taconite has not conducted any formal engineering or mass balance studies. United Taconite has been working internally and with the burner manufacturer to better understand
the new tri

- fuel burner that was installed in August 2011 as part of the recent air permit amendment project. In March 2012, United Taconite, with the help of Clif fs Technology Group, experimented with different burner and coal mill adjustments. These preliminary results showed that United Taconite may have some opportunities to influence its NO
x emissions, but

not without penalties to fuel use, pellet quality

, kil n build up, production rates , or impacts to
other emissions . More studies will need to be done under varying operating conditions to
determine whether NO
x emissions can be lowered in a sustainable way to the operation. A
discussion and summary of these results is located in Folder #11 (see “ Utac L

- 1 Burner Observations (03_22_12

- 03_23_12 NOx Tests ) .pdf ” )

.

In 2007, United Taconite attempted to correlate process variables with NO
x emissions data. This project is captured in the e

- mail titled “ 7.5.07.D ouglas Hawkins to Jason Aagenes.with
attachment .pdf”, and is located in Folder #11.

Information that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gi schia of Cliffs Natural Resources and counsel were also
consulted

.

12. Provide an electronic Excel workbook listing the following information from the NOx and/or SO2 continuous emissions monitoring system (CEMS) from the date the CEMS were installed to present. Provide the information on an hourly basis, where applicable. The Excel workbook must include the following:

a. CEMS identifying name or maker;
b. CEMS location;

c. Pollutant monitored;Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 9 of 13 d. Date and time;

e. NOx/SO 2 emissions rate in pounds per million British thermal units (lb/mmBtu); f. Raw NOx/SO 2 in ppm

g. NOx/SO 2 emissions rate in pounds per hour;
h. Flow rate in actual cubic feet per minute (acfm); and
i. Furnace temperature in O F.

a. United Taconite has three Sick Maihak GM31 In

- situ Gas Analyzers installed.
b. The CEMS are located on United Taconite’s furnace waste gas stacks

– one CEMS on EU040 (Line 1

– SV046) and two CEMS on EU042 (Line 2

– SV048 and SV049).

c. All three CEMS measure SO 2 and NO
x .

Items d., e., f., g., h., and i. are located the workbook titled “UTAC CEMS Data .xlsx ” located
under F older # 12. An explanation of how the calculations were conducted for part e. can also
be found in Folder #12 (see “Calculation Explanation.doc”)

.

Inform ation that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also
consulted

.

13. Provide written ex planation and supporting documents of how the facility could use NOx CEMS for process optimization.

Discussion of this topic was included as part of Cliffs’ United Taconite 2006 BART Analysis , and is reprinted here for reference.

“Process Optimization with NO
x CEMS or Other Parametric Monitoring

MPCA guidance lists “NO
x CEMS” as a work practice/operational change for controlling NO
x emissions. Parametric monitoring is a possible derivation of this alternative.

Based on conversat ions with MPCA staff, this work practice would include process adjustments, or optimization, to minimize NO x emissions. The impact of the process adjustments would be measured using the NO
x CEMS. This approach has been used in the electric utility indust ry to fine tune NO
x emissions from boilers.

One taconite plant has installed NO
x CEMS to monitor emissions, but not to optimize NO
x emissions through process fine tuning. That plant has experienced some reduction in NO
x emissions, but these encompass mu ltiple variables and are not attributed to process fine tuning
with the NO
x CEMS. Therefore, this alternative has not been demonstrated in the taconite industry.

T here are several concerns with utilizing process optimization as an available, applicable a nd technically feasible control option for the taconite industry:Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 10 of 13  Taconite furnaces are designed and operated to convert magnetite to hematite in the presence of excess oxygen and require heat input to initiate the reaction which is
exothermic and releases heat once initiated. Fuel combustion is only part of the process and therefore this process is different from a boiler.

 The quality of the process feed material to the furnace is variable at some taconite operations and product quality may be com promised by attempting to fine tune heat input
to minimize NO x formation.

 At some operations, the operating parameters which generally influence the rate of NO
x generation such as flame temperature, fuel usage and excess air are relatively constant during operation of the furnace, independent of process operation variability. This indicates
that NO
x formation is not dependent upon controllable operating parameters. In the absence of controllable parameters, process optimization would not be effective at

co ntrolling NO
x emissions.

Based upon this information, there is no indication that further emission reductions would be achieved through the use of the process optimization, using NO
x CEMS or other parametric monitoring, as a control technology. Therefore , process optimization as a control option will not
be e valuated further in this report ” (p . 46

- 47

, 2006 United Taconite BART Analysis )

.

The United Taconite BART report is available in its entirety in Folder # 13 (see “2006 United Taconite BART Analysis. pdf”)

.

In summary, CEMS are used to provide real time emissions data. Although they are useful in understanding the facility’s emissions, they are not intended or designed to be a process control tool. The pelletizing process is controlled through monit oring operations, and adjustments are
made to run the kiln s as fuel efficiently as possible, while operating at the appropriate conditions, such as temperature
, to maintain pellet quality.

Also included as part of this response is an e

- mail from Barr Engineering outlining a discussion with regards to NO
x generation and optimization with CEMS ( see “ 12Jul2006 Barr Discussion of Process optimization.pdf ”

– Folder #13).

Information that was use d or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also
consulted

.

14. For the period from January 1, 2002, to the date of receipt of this letter, provide NOx emissions data from each indurating furnace fo r each day, and also for a thir ty

- day rolling average.

Daily NO
x emissions data for each furnace, including the 30

- day rolling average, is located in
Folder #14 (see “ Daily NO
x Emissions .xlsx” ). The data dates back to the initial certification date
of each CEMS.Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 11 of 13 Information that was used or considered in preparation of this response was provided by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite. Scott Gischia of Cliffs Natural Resources and counsel were also
consulted

.

15. Identify all NOx emission sources and factors contributing to NOx emissions at the facility’s indurating furnaces, including but not limited to, the burners

.

Understanding of NO
x generation in indurating taconite furnaces is relatively young as compared to more traditional burners in the power industry, but continues to evolve. NO x in a Grate

- Kiln system is primarily influenced by flame temperature, turbul ence in the flame, length of time in the flame, and oxygen content. Burning zone temperature, quantity of secondary air, and oxygen content are process driven and are difficult to adjust without affecting pellet quality. Anything that would significantly change the burner or burner performance cannot be completed without understanding the effects on pellet quality and production rates.

NO x formation and emission sources have been studied through collaboratively funded efforts
between all of the taconite companies through the Iron Ore Cooperative Research group. Three
of the relevant studies are located under Folder #15. Outside of these studies, no additional work has been conducted by United Taconite.

Also included in Folder #15 is a May 12, 2006 e

- ma il correspondence from Barr Engineering outlining a planned conference call to ‘discuss NO
x emissions data’ (see 12May 2006 Barr Conference Call on Kiln NOx Emissions.pdf”)

.

Information that was used or considered in preparation of this response was provi ded by Candice Maxwell

, Lisa Weidemann, and Jennifer Krause of United Taconite, and Tom Dostal, retired from United Taconite. Scott Gischia of
Cliffs Natural Resources and counsel were also consulted

.

16. Identify all persons, including employees, consultants, representatives of the taconite industry, or representatives of air pollution control manufacturers, who assisted in the preparation, or were consulted for the purpose of preparing, the BART report.

Individuals who assisted in the preparatio n, or were consulted for the purpose of preparing, the

2006 BART report, included the following:

Name Organization Bradley Anderson United Taconite, Environmental Manager until 2007 Jason Aagenes United Taconite, Environmental Manager until 2009

Tom Dostal United Taconite, Senior Process Engineer, retired in 2011 George Pruchnofski Barr Engineering, Principal in Charge
Beth Havlik Barr Engineering , Project Manager
Teresa Kinder Barr Engineering , Technical Resource Jack Kennedy Barr Engineering

, Technical Resource
Erik Boleman Barr Engineering , Technical ResourceResponse to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 12 of 13 Information that was used or considered in preparation of this response was provided by Candice Maxwell of United
Taconite

, and George Pruchnofski, Beth Havlik , Jack Kennedy, Erik Boleman, and Teresa Kinder of Barr Engineering.
Scott Gischia of Cliffs Natural Resources and counsel were also consulted

.



### Table of Contents

Folder Title Contents

#1 Process Diagrams (folder) Pages from 13700011

- 001 Air Permit

- Mine.pdf Pages from 13700113

- 005 Air Permit

- Plant.pdf

#2 Burner Manufacturing Specifications (folder) Allis Chalmers flowsheet information all plants.pdf Operating Data.xlsx UTAC Pages from Supplemental Regional Haze SIP

- March 2012 Citizen's Board.pdf Process Diagram Temp Explanation.doc Summary Table Furnace Line Specs.xlsx

#3 Natural Gas Usage.xlsx

#4 Pages from 13700113

- 005 Air Permit

- Fuel Sampling.pdf Weekly Coal Analysis.xlsx

#5 [17] MPCA AQD Air Emission 13700113

- 005 UTC June 8

- 17,2004 Part 1.pdf [17] MPCA AQD Air Emission 13700113

- 005 UTC June 8

- 17,2004 Part 2.pdf [18] United Taconite Co Dec 28,30 2004

- Jan 5,2005.pdf [19] United Taconite Co May 2

- 5 2005 part 1.pdf [19] United Taconite Co May 2

- 5 2005 part 2.pdf [22] United Taconite Co April 25

- May 4, 2006.pdf [33] United Taconite December 8, 10, 15, 16 2009.pdf [40] United Taconite Line 2 SAM Report April 2011.pdf [43] United Taconite December 2011 (SV046) Performance Tests.pdf Pages from 13700113

- 005 Air Permit

- Stack Test Process Rates.pdf Summary of Stack Test Reports.xlsx

#6 NOx and SO2 PTE.xlsx

Supporting
Documents #7

- 9 9May2006 Barr to MPCA SOx NOx Control Technologies.pdf

Furnace 5 Restart Vol I BACT.pdf

Guidance for Facilities Conducting a BART Analysis.pdf
Potential Impacts of the Federal Regional Haze and Best Available Retrofit Technology Rules on the Taconite Industry in Minnesota.pdf
Regional Haze Regulations and Guidelines for BART Determinations pp 39164

- 39172.pdf

#7 E

- mail Correspondence (folder) Mass Balance Studies (folder)Response to Items Listed in Appendix C of EPA Request for Information
Addressed to United Taconite Received April 6, 2012 Page 13 of 13 CueCost Workbook.pdf Evaluation of Minnesota Taconite Wet Scrubbers.pdf Revised BART Analysis Submittal

- Line 2 SO2 control.pdf

STS Consultant Email

- Cost to Increase Scrubber Efficiency UTAC Dry ESP Feasibility Study_01

- 30

- 09.pdf

#8 1.31.07.Jason Aagenes to Mary Jean Fenske.with attachment.pdf Agenda CCI BART Issues Meeting 08

- 09

- 06.pdf Vogt Vendor Budget Estimate (redacted).pdf

#9 Metso OFA Email.pdf

#10 Manufacturers contact info.xlsx

#11 7.5.07.Douglas Hawkins to Jason Aagenes.with attachment.pdf

Utac L

- 1 Burner Observations (03_22_12

- 03_23_12 NOx Tests).pdf

#12 Calculation Explanation.doc

UTAC CEMS Data.xlsx

#13 12Jul2006 Barr Discussion of Process optimization.pdf 2006 United Taconite BART Analysis.pdf

#14 Daily NOx Emissions.xlsx

#15 12May2006 Barr Conference Call on Kiln NOx Emissions.pdf 058 Thermal NOx Formation In A taconite Pellet Rotary Kiln.pdf

950929 Formation of NOx in Iron Oxide Pelletizing Furnaces.pdf
960425 Model and Simulation of Heat Transfer, Magentite Oxidation and NOx
Formation in a Grate

- Kiln Taconite Pellet Induration Furnace.pdf

#16 No Associated Documents