## 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

March 24, 2010



### Ms. ChrissyBartovich U.S. SteelCorporation Minnesota

OreOperations P.O. Box 417 Mt. Iron, MN 55768 DearMs. Bartovich: The Minnesota Pollution Control Agency (MPCA) is in receipt of the following documents recently submitted by US Steel Corporation Minnesota Ore Operations (Minntac): the Nitrogen Oxides (NOx) Reduction ProgressUpdate dated February 15,2010, and the Computational Fluid Dynamics (CFD) modeling study results dated February 18,2010. The NOx Reduction Progress Update was submitted in response to the MPCA's January 12,2010, letter to Minntac. The CFD modeling report was submitted per the requirements of Air Emissions Permit No. 13700005-005. 

### CFD Modeling Minntac requestedthat the CFD modeling report submitted on February 18,2010, be considered confidential. Minntac must certify that the submittal qualifies for confidential treatmentand provide the appropriate rationale. Minntac should complete and submit to the MPCA the Confidentiality Certification Form (CR-03) to justify why data in the CFD modeling report qualifies for not public treatmentbasedon Minn. Stat. § 13.37and 116.075.The form describes how confidential information must be submitted to the MPCA. Pleasenote that only specific data within a submittal canbe considered confidential and not the entire document. You will needto submit a public version of the documentasexplained on Form CR-O3.The MPCA will review your,r~questand respond in writing. In addition, aswe have discussed previously, when CFD modeling reports, with the confidential arrange a meeting with the MPCA staff, the Federal Land Managers (FLMs), Minntac representatives,and the CFD vendorsto discussand understandthe contentsof the report. Proposed Installation Schedule for Low-NOx Main Burners On April 16, 2009, the MPCA approved an installation schedulefor low NOx main burners. Minntac's February 15,2010, letter contained an alternative schedulethat did not replicate the MPCA-approved schedule. Minntac should follow the scheduleapproved on April 16,2009. Based on the approved scheduleand recentconversationswith Minntac, the MPCA believes that Minntac will have the information that it needsto determinethe degreeof effectivenessof the main burners by mid-July. The MPCA will initiate a meeting with Minntac in July to discussthe NOx reduction being achieved by the Low-NOx Main Burners and the next steps.

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

### Ms. ChrissyBartovich

Page 2

Proposed Pilot Test Schedule for Regenerative Selective Catalytic Reduction (RSCR) Minntac's proposed RSCR schedulewould require submittal of the permit applicability determination for the pilot test in mid-October, atthe earliest.As statedabove,the MPCA believes that Minntac will have the information that it needs to determine the degreeof effectiveness of the Low NOx Main Burners in July 2010. If the Low NOx Main Burners, in combination with processoptimization, do not achievethe predicted NOx reductionsof 60-90 percent, the MPCA would like Minntac to proceedwith pilot testing of RSCRtechnology. In order to minimize delay, Minntac should completethe preparation work needed to pilot RSCR before July, including catalyst poison testsand requisite technical meetings with Babcock Power, the MPCA and FLMs. The MPCA is happyto provide any assistancein completing thesetasks. 

### LoTOx At this time, the MPCA is not requiring further activities related to a LoTOx pilot test at Minntac. The MPCA will continue to discuss potential applications of LoTOx at taconite facilities with the technology vendor, and include Minntac in those discussions when appropriate. Discussions regarding LoTOx pilot tests at Minntac will resume if the Low-NOx main burners do not achieve the predicted reductions. The MPCA looks forward to continued work with Minntac on potential NOx reduction technologies. We encourage continued regular communication between MPCA and Minntac regarding the NOx reduction technology testing efforts. Please contact me or Suzanne Baumann if any communication, in addition to those required in approved schedules, would be useful.



### ",L...,, r 

### Sincerely, 

# {J( Christopher \ Nelson, P.E., Man,ager Metallic Mining Sector' Industrial Division CJN/SB :rn1


### cc: TishieWoodwell,US Steel Mike Dzurinko,US Steel Chrissy Bartovich,US Steel RyanSiats,

US Steel Stephanie

Campbell,

US Steel Suzanne Baumann,

MPCA OwenSeltz,MPCA Hongming

Jiang,MPCA