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 process 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 of the process stages described.

Process Description:

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 trucks, 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 facility 

and then loaded onto rail cars and is transported off-site1

. 

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 covered 

conveyor to the fines crusher building where it is immediately crushed at the third stage 

crushers or sent to the coarse ore surge stockpile. The coarse ore surge pile is used to store ore 

between train shipments or during times when the crusher is down.

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-magnetic 

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 as 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 Description of Induration Process:

As stated above, United Taconite owns and operates two travelling grate kilns. The first 

indurating furnace, referred to as Line 1, consists of a travelling grate, kiln, and annular cooler. 

The traveling 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 section 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 ft3

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 refractory lined cooler (50’ Dia. 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 forced 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 indurating furnace is referred to as Line 2. Line 2 is operationally similar to Line 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 Line 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 and enter an Allis-Chalmers kiln, 22’6” in diameter and 130’ 

long (43,100 ft3 working volume). Air enters the kiln from the first stage of cooling at 2000-2200 

°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’ Dia. 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 duct 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 Folder #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 not 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 also 

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 include, 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 Implementation 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, petroleum coke, and other fuels of

400 MMBtu per hour.” It should 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 are 

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 United Taconite 

believes to be the most accurate depiction of its 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 verifying 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 workbook.

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 Units
Response 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 Folder #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 documentation 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 Emissions Permit 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 collected 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 construction 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 line, 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 states that, “We are requesting information on the facility’s 

furnaces and other nitrogen oxide (NOx) and sulfur dioxide (SO2) emitting units at the facility.” 

As such, the response to this question has been provided to be consistent with that request, and

focuses on SO2 and NOx 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 NOx or SO2 are located in Folder #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 

Air Emissions Permit 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 

(SO2) 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 received approval for an amendment to its air permit (Green 

Production Project). As part of the permit amendment, United Taconite agreed to emission 

reductions for NOx and SO2. The potential to emit calculations in the workbook located under 

Folder #6 reflect the more restrictive limits taken by United Taconite as part of that amendment

(see “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 

consulted.

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 Request, 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 establish 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", July 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 Taconite 

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 members 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 Reactivation 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 NOx and SO2 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 Natural 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”), discusses the low efficiency of the 

facility’s wet scrubbers for SO2. Provide all documentation, including reports and studies, to 

determine the current SO2 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 MPCA 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 

existing scrubbers for SO2 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 SO2 wet 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 Correspondence” located in Folder #7.

United Taconite conducted a feasibility study on installation of a Dry ESP. This study was 

conducted as part of the “Green Production Project” 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, allowing 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 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.

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 SCRs at the facility’s indurating 

furnaces.

Low NOx 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 Supporting Documents #7-9). In addition, as described in the “2006 United 

Taconite BART Analysis.pdf” (see Folder #13), page 42, if low NOx burners were to be applied in 

the indurating zone of the furnace, the reduced flame temperatures associated with Low NOx

burners would adversely affect taconite pellet product quality. Low NOx burners have not been 

applied to the indurating zone of any grate-kiln taconite furnace. Therefore, this option is not 

viable.

SCR: See budgetary estimate from Vogt Power dated October 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 Documents #7-9).

The availability and technical feasibility of both low NOx 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 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.

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 Resources 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 see the attached document entitled “Manufacturers contact info.xlsx” found in Folder 

#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, including 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 Cliffs Technology Group, 

experimented with different burner and coal mill adjustments. These preliminary results 

showed that United Taconite may have some opportunities to influence its NOx emissions, but 

not without penalties to fuel use, pellet quality, kiln build up, production rates, or impacts to 

other emissions. More studies will need to be done under varying operating conditions to 

determine whether NOx 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 NOx emissions data. This 

project is captured in the e-mail titled “7.5.07.Douglas 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 Gischia 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/SO2 emissions rate in pounds per million British thermal units (lb/mmBtu);

f. Raw NOx/SO2 in ppm

g. NOx/SO2 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 SO2 and NOx.

Items d., e., f., g., h., and i. are located the workbook titled “UTAC CEMS Data.xlsx” located 

under Folder #12. An explanation of how the calculations were conducted for part e. can also 

be found in Folder #12 (see “Calculation Explanation.doc”).

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.

13. Provide written explanation 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 NOx CEMS or Other Parametric Monitoring

MPCA guidance lists “NOx CEMS” as a work practice/operational change for controlling NOx

emissions. Parametric monitoring is a possible derivation of this alternative.

Based on conversations with MPCA staff, this work practice would include process adjustments, 

or optimization, to minimize NOx emissions. The impact of the process adjustments would be 

measured using the NOx CEMS. This approach has been used in the electric utility industry to 

fine tune NOx emissions from boilers. 

One taconite plant has installed NOx CEMS to monitor emissions, but not to optimize NOx

emissions through process fine tuning. That plant has experienced some reduction in NOx

emissions, but these encompass multiple variables and are not attributed to process fine tuning 

with the NOx CEMS. Therefore, this alternative has not been demonstrated in the taconite 

industry.

There are several concerns with utilizing process optimization as an available, applicable and 

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 compromised by attempting to fine tune heat input 

to minimize NOx formation.

 At some operations, the operating parameters which generally influence the rate of NOx

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 NOx formation is not dependent upon controllable operating parameters. In the 

absence of controllable parameters, process optimization would not be effective at 

controlling NOx emissions.

Based upon this information, there is no indication that further emission reductions would be 

achieved through the use of the process optimization, using NOx CEMS or other parametric 

monitoring, as a control technology. Therefore, process optimization as a control option will not 

be evaluated 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 monitoring operations, and adjustments are 

made to run the kilns 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 NOx generation and optimization with CEMS (see “12Jul2006 Barr Discussion of 

Process optimization.pdf” – Folder #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.

14. For the period from January 1, 2002, to the date of receipt of this letter, provide NOx emissions 

data from each indurating furnace for each day, and also for a thirty-day rolling average.

Daily NOx emissions data for each furnace, including the 30-day rolling average, is located in 

Folder #14 (see “Daily NOx 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 NOx generation in indurating taconite furnaces is relatively young as compared 

to more traditional burners in the power industry, but continues to evolve. NOx in a Grate-Kiln 

system is primarily influenced by flame temperature, turbulence 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.

NOx 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-mail correspondence from Barr Engineering 

outlining a planned conference call to ‘discuss NOx 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 provided 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 preparation, 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 Resource
Response 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