U. S. Steel Corporation 

Minnesota Ore Operations 

P.O. Box 417 

Mt. Iron, MN 55768 

CERTIFIED MAIL 7006 0100 0006 4747 9599 

August 17, 2009 

Hongming Jiang 

Minnesota Pollution Control Agency 

520 Lafayette Road N. 

St. Paul, MN 55155-4194 

Re: U. S. Steel Minntac updated pilot testing schedule 

Dear Mr. Jiang, 

In the NOx pilot testing schedule submitted by U. S. Steel Minntac (Minntac) on 

February 27, 2009, Minntac committed to submitting an updated pilot testing schedule 

related to pilot testing opportunities based on additional research and evaluation. The 

original due date was July 31, 2009, but was adjusted due to the schedule approval not 

being received after March 31, 2009 . 

Over the last several months Minntac has been aggressively pursuing different avenues 

towards NOx reduction/control technologies. In addition to making progress on pilot 

testing of the low NOx main burner and Selective Non-Catalytic Reduction (SNCR), the 

U. S. Steel Engineering group solicited vendors to review our process and propose the 

best NOx teclmology for our application. Several Selective Catalytic Reduction (SCR) 

vendors were included in the process, and they ultimately declined to bid. According to 

Mitsubishi Power Systems: "The temperature and layout pose significant challenges for 

SCR. And the same challenges are likely non-issues for other technologies. An example 

of this is how to best extract 100% of the flue gas and treat them in the optimal SCR 

operating range of600 ~ 750F" Other SCR vendors we spoke with had similar 

comments as to teclmical difficulties in using a SCR system on our furnaces, including 

potential catalyst poisons after reviewing a stack test from November 2000 on Line 7. 

A lot of discussion has occmTed in the past as to LKAB KK4 and the installation of SCR 

on that pelletizing line. Very little information has been available on this application 

other than a brochure that the equipment vendor Alstom produced. Alstom was contacted 

by U. S. Steel Engineering and requested to bid on a NOx reduction/control strategy for 

Minntac. Alstom declined to bid. U. S. Steel contacted Alstom and requested they 

reconsider. Alstom declined to bid again. After Alstom declined to bid Minntac had the 

opportunity to sit down with several employees from LKAB on June 25, 2009 including 

their General Manager, Engineering Manager, Manager ofKK4 and several Metso 

employees who assisted in the construction of the KK4 line and SCR system. According 

to the KK4 personnel they had been experiencing issues since startup in October. A 
major difficulty is the very nan·ow temperature range in which the equipment can 

operate. However the KK4 personnel said they have no catalyst poisons in their process 

gas stream. Due to the difficulties they have encountered with the SCR system they are 

cun·ently looking at process optimization and better burners as ways to reduce NOx in the 

future, rather than installing another SCR system. 

After several SCR vendors, most notably Alstom, declining to bid and discussions with 

personnel from LKAB familiar with the SCR system installed at KK4, we believe that 

SCR presents numerous technical difficulties and therefore we will not be pursuing a 

pilot of a SCR system. 

Another technology Minntac has looked at is LoTOx. Minntac previously identified a 

number of issues related to this technology including cross-media impacts and severe 

energy demands. We also understand that the MPCA feels actual data from a taconite 

operation utilizing LoTOx would be beneficial. It is Miillltac's understanding that 

Minnesota Steel will be gathering that infonnation as required by their Title V operating 

pem1it. Since the MPCA will be receiving the data from Minnesota Steel, Minntac does 

not plan on testing Lo TOx. 

Minntac continues to make progress on the SNCR and low NOx main burner pilot tests. 

Nalco-Mobotec has been onsite with equipment and personnel to conduct the SNCR test. 

We are working with a burner manufacturer on designing a low NOx main burner which 

would be a technology that would reduce the generation ofNOx. In addition to the 

eff01ts on the specific pilot tests, resources have been committed to looking at ways to 

reduce N Ox generation through process optimization. We feel reducing the generation of 

NOx is a very promising way to limit NOx emissions in an environmentally responsible 

manner. 

If you have any questions related to this submittal please contact Chrissy Bmtovich at 

(218) 749-7364 or clbmtovich@uss.com. 

Sincerely, 

~ol:.::o {J_;,~ General Manager - Minnesota Ore Operations 

cc: Cill'is Nelson- MPCA 

Suzmme Baumann - MPCA 

Tishie Woodwell- U. S. Steel 

Mike Dzurinko- U. S. Steel 

Clll'issy Bartovich- U. S. Steel 

Ryan Siats- U. S. Steel