# • 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 TechnologyPilotTesting

Dear Ms. Bartovich:

This letter summarizes recent conversations between the MinnesotaPollution Control Agency (MPCA) and US Steel with regard to the nitrogen oxides (NOx) control technologypilottest requirements contained in air emissionspermit 13700005-005 for U.S. Steel Corporation Minnesota Ore Operations- Minntac (Minntac). The air emissions permit for the facility contains stepwise requirements to testNOx control technology with the goal ofachieving greater than 70 percentNOx emissions control from the initial permit limit of 13,300 tons peryearNOx.

Line 7 Low NOx Main Burner Pilot Test Minntac installed a LowNOx Main Burneron its Line 7 in May 2010. On August 2, 2010, the MPCA, Minntac and several oftheFederal Land Managers met in Duluth to discuss the preliminary performance ofthe Line 7 LowNOx Main Burnerpilottest. During that meeting, Minntac staff indicated that they were getting excellentNOx control efficiency while combusting natural gas, but could not achieve the same level ofemissions 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 burnertip would allow them to better evaluate the performance ofthe burnerwhile combusting coal. In a follow-up conference call on September 3, 2010, you indicated that the new burnertip 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 consistentbiomass for burnertesting.

Per its air emissions permit, Minntac is required to collect and submitthe results ofthe pilot test results including: technical feasibility and impact to pellet quality, significantNOx reduction,
cross media impacts, multi-pollutant co-control benefits, energy efficiency or consumption impact, and economic feasibility. The MPCA is required perthe permitto evaluate the control technology using that data. As a result ofunanticipated problems with the burnertip design, Minntac has not been able to optimize the Low NOx Main Burnercontrol efficiency while combusting coal orbiomass. To date, the MPCA has not received any ofthe above required information for the Line 7 Low NOx Main Burnerpilot 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 paperMs. ChrissyBartovich Page 2

In a March 24, 2010, letter the MPCA reaffirmed the schedule for the Line 7 LowNOx Main Burnerpilot testing, as approved by the MPCA on April 16, 2009. Perthe approved schedule, Minntac is required to submit the results ofthe pilottest within 120 days following the evaluation oftheperformance. The new burner was installed in late May/earlyJune, 2010 and commenced evaluation ofpotential emission reductions thereafter. Therefore, within 30 days ofthis letter, please submitthe following preliminary pilot test results for Line 7: technical feasibility and impactto pellet quality, significantNOx reduction, cross media impacts, multi-pollutant cocontrol benefits, energy efficiency orconsumption impact, and economic feasibility, as well as any other relevant information that may be useful for the MPCA's evaluation ofthe technology. Specifically, the MPCA is looking for information regarding the control efficiencies while combusting natural gas, coal and biomass, and an evaluation ofwhether the Line 7 Low NOx Main Burner, ifinstalled on other lines at the facility, is capable ofachieving the required 70 percent orgreaterNOx control efficiency at the facility.

Please also submitwithin 30 days ofthis letter an amended schedule and proposed submittals for continued pilot testing ofthe Line 7 burnerfor 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 Burneron Line 7 and, ifso, whether it will affect the type offuels combusted on the line.

Line 6 Low NOx Main Burner PilotTest 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 Burnerto 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 orFebruary 2011 and start pilot testing.

Priorto proceeding with a full scale demonstration ofany NOx control technology, Minntac's permitrequires submittal ofapilottest report for the MPCA's review and approval. Minntac is required to submit a major permit amendment application 60 days after receipt ofthe MPCA's approval ofNOx emission control pilot testing results. Because there is no way to pilot test a Low NOx Main Burnerwithout full scale installation, the line between a pilot and full scale demonstration and full scale demonstration is blurred. The MPCA considers the installations ofa burner on Line 7 and a proposed installation ofa redesigned burner on Line 6 to be two separate pilottests due to the necessary engineering design changes for operation. Therefore, Minntac is required to collect and submit all ofthe pilottest data required by its air emissions permit for the Line 6 LowNOx burner.Ms. Chrissy Bartovich Page 3

The majorpermit amendment is an importantpart ofthe process because it allows for public participation and provides some level ofregulatory certainty for Minntac as you invest in process orcontrol technology equipment. The MPCA and Minntac should continue discussions on the appropriate timing for the submittal ofa majorpermit 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 thatMinntac is making forward progress with the pilottesting. 

### Therefore, within 30 days ofthe date ofthis 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 ofa quarterlyreport documenting the progress or status ofthe pilot testing effort.



### Other NOx Control Technologies At this time, based on the reported performance ofthe low NOx burner on Line 7, the MPCA is notrequiring further activities related to pilot testing ofRegenerative Selective Catalytic Reduction (RSCR) or Low Temperature Oxidation (LoTOx) at Minntac. That decision will be revisited upon receipt and review ofthe relevant performance data for the Line 7 burner requested in this letter. The discussion ofpotential applications ofother technologies will resume iforwhen it is determined that the LowNOx Main Burnerpilot tests on Line 7 and, potentially, Line 6 are not achieving the needed reductions to comply with airpermit requirements

.
The MPCA looks forward to continuingto work with US Steel on achieving the NOx emission reductions required by its permit. Ifyouhave any questions orconcerns, please call me at 651- 757-2603.
Sincerely,

ChristopherJ. 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