EPA sets nitrogen-oxide (NOx) limits for a taconite (iron-ore) facility — finalizing rules for U.S. Steel's Keetac plant (June 2026)
The U.S. EPA finalized nitrogen-oxide (NOx) emission limits for the indurating furnace at U.S. Steel's Keetac taconite facility (Minnesota), which makes the iron-ore pellet feedstock "taconite." The rule satisfies the "best available retrofit technology (BART)" requirement for improving visibility.
Document overview (primary data)
- Document typeRule
- AgencyEnvironmental Protection Agency
- Citation91 FR 34574
Key points
- EPA finalized NOx limits for the indurating furnace at U.S. Steel's Keetac taconite facility (Minnesota)
- Satisfies the "best available retrofit technology (BART)" requirement for regional-haze/visibility
- On a 720-hour average: 3.4 (natural gas only) / 2.0 lbs NOx/MMBtu (other), enforceable after 3 / 5 years
- Option to adjust the cofiring limit (up to 2.5) based on CEMS data after NOx-reduction tech is installed
- A finalized industrial air rule with multi-year lead time before enforcement
- BART limits are 3.4 lb NOx/MMBTU on natural gas alone (three years) and 2.0 lb on other or blended fuels (five years).
The U.S. Environmental Protection Agency (EPA) revised its 2013 Federal Implementation Plan (FIP), finalizing nitrogen-oxide (NOx) emission limits for the indurating furnace at U.S. Steel's Keetac taconite facility (Keewatin, Minnesota) (a rule, June 8, 2026).
Taconite is an iron-ore feedstock — crushed and concentrated ore processed into pellets usable in blast furnaces — and its processing (indurating) furnaces emit air pollutants.
1Regional haze as the driver
The rule satisfies the requirement to apply "best available retrofit technology (BART)" at taconite facilities as part of addressing "regional haze" that degrades visibility (e.g., at national parks).
The finalized BART limits, all evaluated on a rolling 720-hour average, are: (1) 3.4 pounds of NOx per million BTU when firing exclusively natural gas (enforceable three years after promulgation), and (2) 2.0 lbs NOx/MMBtu when firing any fuel or combination other than exclusively natural gas (enforceable five years after promulgation, unless EPA promulgates a modified limit before then).
2Verification through CEMS
The rule also allows the facility, within 52 months of the effective date, to seek an adjustment of the cofiring limit (not to exceed 2.5 lbs NOx/MMBtu on a 720-hour rolling average) based on CEMS data collected after installing NOx-reduction technology.
3A multi-year path to compliance
This is a concrete example of finalizing specific air-pollution limits for an industrial facility, with multi-year lead time for technology installation — illustrating how U.S. environmental regulation is operationalized.
4The emission limits as finalised
The rule sets more than one limit. The value changes with the fuel and with the timing.
Taconite is an ironmaking feedstock produced by crushing and concentrating iron ore into pellets usable in a blast furnace, and the induration furnaces in that process emit air pollutants. The rule satisfies the requirement for Best Available Retrofit Technology at taconite facilities as part of addressing regional haze, which degrades visibility in national parks and elsewhere.
Why it matters
A concrete example of finalizing specific air-pollution limits (NOx, BART) for an industrial facility. For readers in steel, manufacturing, and environmental compliance, a useful read on how U.S. emission rules and enforcement schedules work.
FAQ
What is taconite?
What is BART?
Sources (primary)
Source: Federal Register (federal documents, public domain). Links go to the official site.