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Minnesota Pollution Control Agency 

520 Lafayette Road North I St. Paul, MN 55155-4194 I 651-296-6300 I 800-657-3864 I 651-282-5332 TTY I www.pca.state.mn.us 

September 23, 2010 

Ms. Chrissy Bartovich 

U.S. Steel Corporation 

Minnesota Ore Operations- Minntac 

P.O. Box 417 

Mt. Iron, MN 55768 

RE: Nitrogen Oxides Control Technology Pilot Testing 

Dear Ms. Bartovich: 

This letter summarizes recent conversations between the Minnesota Pollution Control Agency 

(MPCA) and US Steel with regard to the nitrogen oxides (NOx) control technology pilot test 

requirements contained in air emissions permit 13700005-005 for U.S. Steel Corporation 

Minnesota Ore Operations- Minntac (Minntac). The air emissions permit for the facility contains 

stepwise requirements to test NOx control technology with the goal of achieving greater than 70 

percent NOx emissions control from the initial permit limit of 13,300 tons per year NOx. 

Line 7 Low NOx Main Burner Pilot Test 

Minntac installed a Low NOx Main Burner on its Line 7 in May 2010. On August 2, 2010, the 

MPCA, Minntac and several ofthe Federal Land Managers met in Duluth to discuss the preliminary 

performance of the Line 7 Low NOx Main Burner pilot test. During that meeting, Minntac staff 

indicated that they were getting excellent NOx control efficiency while combusting natural gas, but 

could not achieve the same level of emissions reductions when combusting coal and biomass. 

Minntac engineers indicated that they were unable to achieve the optimal flame shape while 

combusting coal and hoped that a recently received redesigned burner tip would allow them to better 

evaluate the performance of the burner while com busting coal. In a follow-up conference call on 

September 3, 2010, you indicated that the new burner tip was not producing the necessary flame 

shape while combusting coal. With regard to biomass, Minntac engineers reported problems with the 

biomass fuel handling system and had been unable to deliver consistent biomass for burner testing. 

Per its air emissions permit, Minntac is required to collect and submit the results of the pilot test 

results including: technical feasibility and impact to pellet quality, significant NOx reduction, 

cross media impacts, multi-pollutant co-control benefits, energy efficiency or consumption 

impact, and economic feasibility. The MPCA is required per the permit to evaluate the control 

technology using that data. As a result of unanticipated problems with the burner tip design, 

Minntac has not been able to optimize the Low NOx Main Burner control efficiency while 

combusting coal or biomass. To date, the MPCA has not received any ofthe above required 

information for the Line 7 Low NOx Main Burner pilot test. 

St. Paul I Brainerd I Detroit Lakes I Duluth I Mankato I Marshall I Rochester I Willmar I Printed on 100% post-consumer recycled paper 
Ms. Chrissy Bartovich 

Page 2 

In a March 24, 2010, letter the MPCA reaffirmed the schedule for the Line 7 Low NOx Main 

Burner pilot testing, as approved by the MPCA on April 16, 2009. Per the approved schedule, 

Minntac is required to submit the results of the pilot test within 120 days following the evaluation 

ofthe performance. The new burner was installed in late May/early June, 2010 and commenced 

evaluation of potential emission reductions thereafter. Therefore, within 30 days of this letter, 

please submit the following preliminary pilot test results for Line 7: technical feasibility and 

impact to pellet quality, significant NOx reduction, cross media impacts, multi-pollutant cocontrol benefits, energy efficiency or consumption impact, and economic feasibility, as well as 

any other relevant information that may be useful for the MPCA's evaluation of the 

technology. Specifically, the MPCA is looking for information regarding the control efficiencies 

while combusting natural gas, coal and biomass, and an evaluation of whether the Line 7 Low NOx 

Main Burner, if installed on other lines at the facility, is capable of achieving the required 70 

percent or greater NOx control efficiency at the facility. 

Please also submit within 30 days of this letter an amended schedule and proposed submittals 

for continued pilot testing of the Line 7 burner for the MPCA's review and approval. Given 

the difficulties experienced to date, we are particularly interested any plans to further test coal and 

biomass combustion and whether post-pilot testing Minntac will continue to operate the Low NOx 

Main Burner on Line 7 and, if so, whether it will affect the type of fuels combusted on the line. 

Line 6 Low NOx Main Burner Pilot Test 

During our September 3, 2010, call, you stated that Minntac engineers are working with a vendor 

to redesign and reconfigure a new Low NOx Main Burner to eliminate the flame shape problems 

occurring during coal combustion. Minntac intends to install a redesigned Low NOx Main 

Burner on Line 6 during a planned maintenance shut down in January or February 2011 and start 

pilot testing. 

Prior to proceeding with a full scale demonstration of any NOx control technology, Minntac's 

permit requires submittal of a pilot test report for the MPCA's review and approval. Minntac is 

required to submit a major permit amendment application 60 days after receipt of the MPCA's 

approval ofNOx emission control pilot testing results. Because there is no way to pilot test a 

Low NOx Main Burner without full scale installation, the line between a pilot and full scale 

demonstration and full scale demonstration is blurred. The MPCA considers the installations of a 

burner on Line 7 and a proposed installation of a redesigned burner on Line 6 to be two separate 

pilot tests due to the necessary engineering design changes for operation. Therefore, Minntac is 

required to collect and submit all of the pilot test data required by its air emissions permit for the 

Line 6 Low NOx burner. 
Ms. Chrissy Bartovich 

Page 3 

The major permit amendment is an important part of the process because it allows for public 

participation and provides some level of regulatory certainty for Minntac as you invest in process 

or control technology equipment. The MPCA and Minntac should continue discussions on the 

appropriate timing for the submittal of a major permit amendment application. 

While the MPCA acknowledges the difficulty in setting fixed deadlines for evaluating a novel 

technology with unexpected complications, it is important to ensure that Minntac is making 

forward progress with the pilot testing. Therefore, within 30 days of the date of this letter, 

please propose a schedule and submittals for pilot testing a Line 6 Low NOx Main Burner 

for the MPCA's review and approval. The proposed schedule shall include submittal of a 

quarterly report documenting the progress or status of the pilot testing effort. 

Other NOx Control Technologies 

At this time, based on the reported performance of the low NOx burner on Line 7, the MPCA is 

not requiring further activities related to pilot testing of Regenerative Selective Catalytic 

Reduction (RSCR) or Low Temperature Oxidation (LoTOx) at Minntac. That decision will be 

revisited upon receipt and review of the relevant performance data for the Line 7 burner 

requested in this letter. The discussion of potential applications of other technologies will resume 

if or when it is determined that the Low NOx Main Burner pilot tests on Line 7 and, potentially, 

Line 6 are not achieving the needed reductions to comply with air permit requirements. 

The MPCA looks forward to continuing to work with US Steel on achieving the NOx emission 

reductions required by its permit. Ifyou have any questions or concerns, please call me at 651-

757-2603. 

Sincerely, 

Christopher J. Nelson, P.E., Manager 

Strategic Projects Sector 

Industrial Division 

CJN/SLB:rm 

cc: Trent Wickman, US Forest Service 

Don Shepherd, National Park Service 

David Pohlman, National Park Service 

Tishie Woodwell, US Steel 

Mike Dzurinko, US Steel 

James Jarvi, US Steel 

Suzanne Baumann, MPCA