U.S. Steel Corporation 

Minnesota Ore Operations 

P.O. Box 417 

Mt. Iron, MN 55768 

CERTIFIED MAIL #7008 1140 0000 4098 5072 

February 15, 2010 

Mr. Christopher J. Nelson, P.E. 

Manager, Metallic Mining Sector 

Minnesota Pollution Control Agency 

520 Lafayette Road North 

Saint Paul, MN 55155-4194 

SUBJECT: Minntac NOx Reduction Progress Update 

Dear Mr. Nelson: 

United States Steel Corporation, Minnesota Ore Operations - Minntac (Minntac) has 

received the letter dated January 12, 2009, from the Minnesota Pollution Control Agency 

(MPCA) regarding the progress Minntac has made in regards to the retroactive PSD 

permitting requirements of Minntac's Title V air emissions permit. Since receipt of the 

letter, discussion occurred between U.S. Steel and the MPCA on February 2 and 8, 2010, 

updating the MPCA on the progress of the designed low NOx main burner and projected 

reductions. As requested in the January 12 letter and subsequently discussed during the 

February 2, 2010 call, U.S. Steel is providing a written update on the progress of meeting 

the 70% reduction goal from the baseline of 13,300 tons NOx per year. Also attached is a 

proposed updated pilot test schedule. 

Status of CFD Model and Low NOx Main Burner 

The original Engineering Report conducted by Hatch (NOx Reduction Analysis report, 

January 30, 2009) had a NOx reduction of 10-20% from the installation of an "off the 

shelf' low NOx main burner. Over the past year, Minntac has been working with Hatch 

and Coen to design a burner specifically for Minntac's indurating Line 7 and associated 

fuel mixes to optimize the burner characteristics and ultimately reduce the generation of 

thermal NOx. 

As a permit condition, CFD modeling was initiated to model the indurating generation of 

NOx to further the investigation of potential reductions in NOx in the indurating process. 

Utilizing the CFD model developed by Hatch, the low NOx main burner designed by 

Coen was modeled to predict NOx reductions associated with its installation. The 

preliminary results predict significant reductions in NOx generation from the installation 

of the burner. For the main fuel mix scenarios typically utilized at Minntac, the model 

predicts the following range of reductions in NOx generation from existing emission 

levels: 
Fuel Mix 

Coal & Natural Gas 

Biomass & Natural Gas 

Coal/Biomass/Natural Gas 

Percent Reduction 

60-90% 

80-90% 

60-90% 

These reductions are in line with the goal of a 70% reduction from the 13,300 tons of 

NOx per year baseline. A fmalized CFD modeling rep01t will be submitted on February 

18, 20 I 0. This report will include an original validated CFD model and CFD results for 

the designed low NOx main burner. 

Cunently, U. S. Steel plans on installing the designed low NOx main burner on Line 7 in 

April 2010. The major repair for Line 7 is being scheduled around burner an·ival which is 

cunently estimated at mid April. Upon initial startup, U. S. Steel will determine if there 

are any fatal flaws with the bumer within 45 days. To thoroughly evaluate the 

performance of the new low NOx main burner, a full scale demonstration will take 

approximately 6 months. However, to ensure time is not lost towards progressing 

towards the NOx reduction goal should the burner not demonstrate reductions in line with 

the goal, U. S. Steel will proceed clown a parallel path by fm1her investigating RSCR 

technology for a pilot test. 

Regenerative Selective Catalytic Reduction (RSCR) Pilot Testing 

During the week of February 8, 2010, Minntac representatives met with Babcock Power 

(Babcock) representatives to discuss the RSCR technology. Based on initial discussions it 

was clear the Babcock representatives did not have a good understanding of the area the 

technology would potentially be located. A tour was provided to aid in the understanding 

of the process and facility layout including the space limitations due to railroad tracks and 

other infrastructure. Babcock was requested to schedule a technical presentation for 

Minntac in the near future. Babcock was also asked to provide additional information on 

catalyst poisons that Minntac should test for in the scrubber exhaust. As noted by MPCA, 

previous poisons tests were conducted on the duty side. Minntac plans to schedule a 

catalyst poisons test following the teclmical presentation by Babcock 

Low Temperature Oxidation (LoTOx) Pilot Testing 

U. S. Steel received contact information from the MPCA in regards to the LoTOx 

technology. U. S. Steel representatives have attempted to contact the vendor, but have 

received no response to date. Due to the lack of response, U. S. Steel, in agreement with 

the MPCA, will proceed with continuing evaluation of the RSCR teclmology should it be 

deemed necessary to pilot test due to a lack of success from the installation of a low NOx 

main burner. 

Enclosed is an updated pilot testing schedule as requested. Minntac has expended a great 

deal of time and effort on the new low NOx main burner to hopefully ensure a successful 

application with a significant reduction in thermal NOx generation. Based on CFD 

modeling we are very encouraged by the potential of this application. As previously 

discussed a reduction in NOx generation is extremely beneficial for many reasons. Add 

on controls have the potential for cross media impacts, increases in other pollutants and 
energy impacts which relate to C02 emissions. Based on the information we currently 

have the new low NOx main appears to meet the goals of all interested pmiies. Even 

though we are confident in the burner we will continue to investigate RSCR as a parallel 

path in the event that the burner does not perform to the level anticipated. 

Based on previous misunderstandings we feel keeping the lines of communication open is 

important. The comprehensive CFD modeling will be submitted on February 18, 2010. 

We suggest a meeting be set up after MPCA and the Federal Land Managers have time to 

review the document. If it would be beneficial to have Hatch involved to explain the 

model and results, U. S. Steel will coordinate a meeting. 

If you have any questions or would like any additional information please feel free to 

contact me at (218) 749-7364 or clbartovich@uss.com. 

~~

~e ely, .fl . ~ l ( 

Vlv' 

Chrissy Bartovich 

Manager -Environmental Services 

Minnesota Ore Operations 

United States Steel Corporation 
United States Steel Corporation 

Minnesota Ore Operations - Minntac 

NOx Pilot Testing Schedule 

February 15, 2010 

Description 

Pilot Test No. 1 -Low NOx Main Bumea· 

1. Complete engineering evaluation of Low NOx burner 

options for replacement of main burner. 

2. Submit required applications/requests for pilot test 

approval 

3. Receive permit or written approval from MPCA that no 

permit(s) are needed. 

4. Appropriate funds for the burner trial. 

5. Install burner during major repair 

6. Initial startup after installation. 

7. Complete initial evaluation of performance. 

8. Complete full scale evaluation. 

9. Submit final rep01t to MPCA 

Pilot Test No. 2- RSCR 

I. Schedule initial meeting with manufacturer/vendor to 

conduct pilot test. 

2. Conduct meeting with technical representatives from both 

organizations. 

3. Complete catalyst poisons test pending additional 

information from vendor and stack test crew availability 

4. Submit poisons test information to vendor and MPCA 

5. Schedule meeting with MPCA and vendor to discuss 

results of poisons test 

6. Submit permit applicability determination for pilot testing 

if no technical issues are found and burner is not 

performing as expected. 

Milestone Date* 

June 1, 2009 

June 30, 2009 

November 20, 2009 

February 26, 20 I 0 

Mid-April 

30 days after Step 5 

45 days after Step 6 

180 days after Step 7 

60 days after Step 8 

February 9, 2010 

60 days after Step 1 

60 days after Step 2 

45 days after Step 3 

30 days after Step 4 

30 days after Step 5 
7. Receive permit or written concurrence from MPCA no TBD-MPCA 

permit needed for pilot testing 

8. Appropriate funds for the RSCR trial 60 days after Step 7 

9. Construction of pilot test equipment- Babcock Power 7 months after Step 8 

I 0. Mobilization of pilot test equipment on-site. 1 month after Step 9 

II. Begin evaluation of performance l month after Step 10 

12. Complete evaluation of performance 6 months after Step 11 

13. Submit results of performance evaluation. 2 months after Step 12 

*An interim milestone date, which if missed, ts not a violation provided that the final compliance 

date(s) are met.