U.S. Steel Corp. operates a taconite mine and processing plant known as Keetac north of Keewatin, where it produces taconite pellets for use at iron and steel mills.
Keetac operates under existing air and water permits. The MPCA will update these permits based upon current air and water rules.
Our role
The MPCA is responsible for issuing and enforcing permits that limit emissions from Keetac’s operations to protect the environment and health of Minnesotans. Those permits reflect current state law and regulations.
The MPCA received an air permit application from Keetac in August 2009 and has drafted a permit for the facility that went up for public comment in May 2024. In September 2023, Keetac submitted revised applications for an industrial wastewater permit that the MPCA is now reviewing.
Project information
U.S. Steel has operated the Keetac facility since 1967 and currently produces about 6 million tons of taconite pellets per year.
Keetac recently added a production line that gives the facility the flexibility to make either direct reduction pellets with a higher iron content or traditional blast furnace pellets. The existing furnace will fire whichever pellet is being produced and emissions are expected to be the same. New binder storage and handling equipment for the direct reduction pellets are equipped with HEPA filters. The permit requires Keetac to operate and maintain the HEPA filters so they are in continuous compliance with the new limits.
Pollutants of concern from this facility include volatile organic compounds, carbon monoxide, nitrogen oxides, sulfur dioxide, particulate matter, carbon dioxide equivalent, hazardous air pollutants, mercury, and lead.
To control particulate matter emissions from ore crushing and pellet handling, the facility uses either wet scrubbers or fabric filters. Wet scrubbers control particulate matter, sulfur dioxide, and mercury emissions from the indurating furnace. Also, in accordance with the facility’s fugitive dust emission control plan, the operation periodically checks for visible emissions. The fugitive dust control plan includes control methods to keep particulate matter from becoming airborne from ore mining and hauling operations, the tailings basin, storage piles, and material transfer activities with multiple methods depending upon the source.
Keetac currently operates under a Part 70 operating permit. The air permit renewal includes the direct reduction grade concentrate and pellets project and rolls in several other permit amendments.
Key changes and updates to the permit include:
- replacement of an emergency engine
- replacement of wet scrubbers with more efficient fabric filters and HEPA filters
- approvals for wet scrubber control equipment replacements
- removal of previously permitted phase III operating line
- inclusion of the U.S. Environmental Protection Agency performance test waiver approval and alternative monitoring plan
- regional haze Federal Implementation Plan language
- demonstration of mercury control efficiency
- demonstration of National Ambient Air Quality Standards compliance demonstration
- performance test plans and frequencies updates
- an updated fugitive dust emissions control plan
Next steps and timeline
The MPCA issued the facility's air permit on Jan. 16, 2025, and expects to issue a final wastewater permit later in 2025.