Minnesota Pollution Control Agency

520 Lafayette Road North I 5t.Paul,MN 55155-4194 I 651-296-6300 I 800-675-3843 651-282-5332 TTY www.pca.state.mn.us

January 12, 2010

Mr. Scott Coleman, General Manager

US Steel Corporation

Minnesota Ore Operations

P.O. Box 417

Mountain Iron, MN 55768

.

RE: Nitrogen Oxides Control Technology Pilot Testing

Dear Mr. Coleman:

This letter is to summarize the progress US Steel (USS) has made to date in meeting the nitrogen

oxides (NOx) emissions reduction requirements ofUSS Minntac's (Minntac) air emissions

permit,_Minntac's air emissions permit requires pilot testing and implementation of NO x

emission reduction technologies, with a goal of greater than 70 percent reduction in NOx

emissions compared to the initial permit limit of 13,300 ton per year NOx,

The Minnesota Pollution Control Agency (MPCA) received the letter dated November 30, 2009,

from Minntac in response to the MPCA's November 6,2009, request for information on

potential pilot testing of Selective Catalytic Reduction (SCR) and Low Temperature Oxidation

(LoTOx) technologies at Minntac. The November 30, 2009, letter contained information

concerning problems pilot testing SCR, including two letters from SCR vendors declining 10 bid,

discussion of optimal operating temperatures for SCR systems, and identification of potential

SCR catalyst poisons in the exhaust gas stream at Minntac. In the letter Minntac requested a

meeting with the MPCA to discuss issues related to LoTOx pilot testing, including timing,

permitting, cross media impacts, and technical feasibility.

On the morning of December 15,2009, representatives from the MPCA, Minntac, the US Forest

Service, and the National Park Service met with Babcock Power (Babcock) to discuss

Regenerative Selective Catalytic Reduction (RSCR) technology and its potential application at

Minntac. Minntac representatives distributed copies of a Babcock RSCR bid dated April 24, 2009,

for pilot and full scale application of RSCR at Minntac. This bid was not previously provided to

the MPCA, despite our November 6,2009, request for any additional information or

correspondence with SCR pilot test vendors. The Minntac permit identifies RSCR as a type of

SCR.

Representatives from the MPCA, Minntac, and the US Forest Service met on the afternoon of

December 15,2009, to discuss progress on current requirements of the Minntac air permit,

including current and potential pilot tests of air pollution control equipment.

St. Paul I Brainerd I Detroit lakes I Duluth I Mankato I Marshall I Rochester I Will mar I Printed on 100% post-consumer recycled paper
Mr. Scott Coleman

Page 2

The following is a brief summary of the current status of the NOx reduction technologies

discussed by Minntac and the MPCA:

Low NOx Main Burners

1.

Minntac contracted with Hatch, an engineering and project management company, to analyze

potential NOx reduction technologies. According to Hatch's January 30, 2009, Project Report,

which analyzed potential NOx reduction technologies for Minntac, Selective Non-Catalytic

Reduction (SNCR), and low N9x main burners in combination had the potential to achieve NOx

reductions approaching the 70 percent reduction goal for the Minntac air permit. In a February

27,2009, letter, Minntac proposed pilot tests for SNCR and a low NOx main burner.

In a letter dated April 16,2009, the MPCA authorized Minntac to proceed with a pilot test of a low

NOx main burrier, in combination with computational fluid dynamics (CFD) modeling and

Mobotec technology. Hatch's January 2009 Project Report estimated a 30 percent reduction in

NOx formation from installation of a low NOx main burner in combination with CFD modeling

and Mobotec. The MPCA approved the specific installation of a low NOx main burner on Line 7 at

Minntac in a letter dated November 20,2009. Minntac plans to install the burner in April 2010, in

accordance with the MPCA-approved schedule for the pilot test.

2. Selective Non-Catalytic Reduction

The MPCA received a letter dated December 9, 2009, from Minntac discussing the feasibility of

SNCR as a technology to reduce NOx emissions at Minntac. A full report on SNCR from

NALCO Mobotec was attached. The report was prepared after pilot testing SNCR, as required by

Minntac's 2009 air emissions permit. In the letter and attached report Minntac and NALCO

Mobotec concluded that SNCR was not a feasibleNOx control technology for full scale

implementation at Minntac.

The MPCA has completed a preliminary review of the report and preliminarily accepts Minntac's

proposal not to implement a full-scale SNCR demonstration project at this time. Demonstrated

NOx reductions in the pilot test were less than 10 percent and the December 9, 2009, report

identified technical problems adapting the technology to an application at Minntac. At this tim~,

the MPCA has not made a determination regarding the technical feasibility of SNCR.

3. 

Selective Catalytic Reduction

Minntac supplied technical information on potential application of traditional "clean side" and

"dirty side" SCR applications that would be installed either before ("dirty side") or after ("clean~

side") existing control equipment. Minntac stated that several vendors declined to bid on a pilot

test project due to technical problems such as the presence of catalyst poisons in the pre-control

equipment gas stream and reheat requirements of the gas stream for effective post-control

applications. The MPCA has not made a determination regarding the technical feasibility of

"clean side" or "dirty side" SCR.

There are other potential control technologies with better chances of success, including RSCR.

At this time, the MPCA will work with Minntac on those technologies.
Mr. Scott ColemanPage 

3

Babcock prese~tedthe technical details ofRSCR technology and potential application at

Minntac at the December 15,2009, meeting. RSCRequipment is designed for installation after

other pollution control equipment and requites significantly less energy for gas stream reheating

than "dirty side" SCR technology. Babcock concluded in its December 15,2009, presentation

and April 24,2009, letter to Minntac that RSCR was technically feasible. Issues raised by

Minntac in writ~en correspondence and/or or~l discussion include:

...

Required amounts of ammonia for proper system operation.

The presence of catalyst poisons in the gas stream and their effects on the RSCR catalyst.

Dust levels in the gas stream and engineering of water flushing to remove dust from the

.

equIpment.Capital 

and operating costs forbumers to reheat the gas stream.

Babcock representatives estimated that an RSCR system could reduce NOx emissions by 70

percent or more, depending on thesy~tem design. Based on discussions between Babcock, the

MPCA, Minntac, and others present, the MPCA has determined that any technical issues related

to RSCR could be studied, in a pilot test and are likely to be factors affecting cost but not

technical feasibility of the technology. Minntac' s permit requires that technologies be selected

for pilot testing based on technical feasibiliry rather than cost.

4. 

Low Temperature Oxidation

In its January 30, 2009', engineering analysis on potential NOx reduction technologies atMinntac, 

Hatch estimated LoTOx could achieve 80 percent reduction in NOx emissions.

Bas~don th,e; information provided in the January, 2009~atch report, the MPCA has concluded

that a LoTOx pilot test is technically feasible. In a November 6,2009, letter, the MPCA requested

from Minntac a schedule to pilot test LoTOx. As discussed in the letter, technical feasibility is the

only criteria allowed by Minntac's permit for consideratio,n when examining technologies for

potential pilot testing. Issues associated with full scale LoTOx implementation; specifically crossmedia pollution impacts and system energy demands, can be studied in a pilot test and evaluated

when determining whether LoTOx is appropriate for a full-scale demonstration project.

5. 

Process Optimization

A report outlining the findings of Minntac's CFD studies is due to the MPCA in February, 2010.

Potential process optimization projects recommended in the CFD report or otherwise developed

by Minntac should be discussed with the MPCA as soon as practicable following submittal of the

report.

Path Forward

Given the results of the SNCR pilot test, it is .likely that pursuit of technologies other than SNCR

will.bemore productive at this time. Technical analyses submitted by Minntac and others

suggest that either I;oTOx or RSCRmay achieve 70 percent or greater reductions in NOx

emissions from Minntac's operations.
Mr. Scott Coleman

Page 4

As 

discussed in MPCA's November 6, 2009, letter, Minntacis obligated by its air permit topropose 

and conduct technically feasible pilot tests that will lead tQ full scale implementation of

NOx emissions reductions attheir facilitY; Therefore, by February 15,2010, please propose pilot test schedules for LoTOx and RSCR for the MPCA 'sreview and approval. .

For your planning purposes, the MPCA has cont~cted vendors for LoTOx and RSCR. BOC Linde

requires three months to prepare its LoTOx equipment for a pilot test. Minntac's proposed pilot

test for LoTOx should include a commencement date for pilot.testirig no later than June 15,2010. Babcock requires seven months tQ fabricate andrleliver a pilot scale RSCR system. As a result, .

Minntac's proposed pilot test schedule for RSCR should include a commencement date for pilot

testing no later than October 15, 20 1 O. Potential RSCR pilot tests should be conducted on Line 6 or

7 at Minntac to most appropriately study the effects of multiple fuels on the control system. Per the

requirements of Minntac's air emissions permit, upon receipt of the proposed schedule, the MPCA

will review the 'Proposal and approve an enforceable schedule for pilot testing.

Finally, 

the MPCA requests all information collected or generated by USS, in whatever format,

that has not already been provided regardingallNOx emission reduction technologies thatUSShas 

considered or investigated to date, including test data, written exchanges with vendors and

bids. Submit information tiy February 15,2010. Minn. Stat..§ 116.091 (2008).

The MPCA looks forward to continuing to work with Minntac on potential NOx reduction

technologies. Please contact me with any questions or concerns at 651-757-2603.

Si

Christopher J. Nelson, P .E.., Manager

Metallic Mining Sector

Industrial Division

CJN/SV:rm

cc: 

Tishie Woodwellt US Steel

Mike Dzurinkot US Steel

Chrissy Bartovicht US Steer

.

Ryan Slatst US Steel

Stephanie Campbellt US Steel

Suzanne Baumannt MPCA

Owen Seltzt MPCA

Hongming Jiangt MPCA