The U.S. Environmental Protection said in an Aug. 15 Federal Register notice that it is proposing a Federal Implementation Plan (FIP) to address the requirement for best available retrofit technology (BART) for largely gas-fired taconite plants in Minnesota and Michigan.
BART is a requirement of EPA’s regional haze rule which has not been satisfied by Minnesota or Michigan for its subject taconite plants, the agency said. EPA developed this proposal in response to an inadequate BART determination by Michigan for its one subject taconite source. On June 12, EPA approved revisions to the Minnesota State Implementation Plan (SIP) addressing regional haze but also announced that in response to comments it was deferring action on emission limitations that Minnesota intended to represent BART for its taconite facilities.
Taconite is a form of iron ore that is produced in northern Minnesota and the extreme southwest corner of Michigan’s Upper Peninsula. It is processed in facilities often fueled by natural gas, with the EPA in the notice running down various emissions controls, including SO2 scrubbers, that might be needed for those facilities. These controls are basically the same as used on power plants. Affected companies include U.S. Steel and Northshore Mining.
EPA is proposing to determine that the FIP satisfies requirements of the Clean Air Act that require states, or EPA in promulgating a FIP, to establish BART for applicable sources. It is taking comment on the proposed FIP until Sept. 28. It will also hold a hearing on Aug. 29 at the offices of the Minnesota Pollution Control Agency.
The U.S. taconite iron ore industry uses two types of pelletizing machines or processes: straight-grate and grate-kiln, EPA noted. A significant difference is that straight-grate kilns do not burn coal and they therefore have a much lower potential for emitting SO2.
EPA proposes, for example, to find that BART for NOX for indurating furnaces is low-NOX burners for both straight-grate and grate-kilns.
Coal does figure into this in a limited way. For example, at the U.S. Steel Minntac facility, Lines 3, 4, and 5 are burning natural gas and wood, both of which are low in sulfur. Lines 7 and 8 are allowed to burn coal. Due to the uncertainty of alternative fuel costs, the potential of replacing one visibility impairment pollutant for another, and the fact that BART cannot mandate a fuel switch, Minntac did not evaluate the use of dried coal at those lines as a BART option. Another covered facility with coal capability is run by United Taconite.