U.S. Steel Minntac
Large load · 8819 OLD HIGHWAY 169, Mountain Iron, MN
Minntac, in Mountain Iron on Minnesota's Mesabi Iron Range, is U.S. Steel's taconite pellet plant and the largest single taconite producer in Minnesota. Its pellets are the primary feed for blast-furnace steelmaking, and a majority of them are shipped to U.S. Steel's Gary Works in Indiana. The plant draws its electricity from Minnesota Power, the ALLETE utility, under a negotiated electric supply agreement; a 2016 account put the plant's consumption on a par with a city the size of Duluth. Nippon Steel acquired U.S. Steel in 2025 and U.S. Steel has said about $890 million of the promised new investment will go to Minntac and/or Keetac.
Overview
- Average demand
- 250 MW
- operating · Sep 24, 2025
In October 2016 ALLETE announced that Minnesota Power had signed a five-year agreement to supply electricity to U.S. Steel's two Iron Range taconite plants, Minntac in Mountain Iron and Keetac in Keewatin, and filed a petition with the Minnesota Public Utilities Commission for approval. At the time Keetac was closed, and the Duluth News Tribune described Minntac as the state's largest single taconite producer using about as much electricity as a city the size of Duluth. In Minnesota Power's 2023 rate case an administrative law judge recorded the utility's own statement that more than half of its retail sales come from just two mining customers, U.S. Steel and Cleveland-Cliffs, and that U.S. Steel is a member of the Large Power Intervenors group of Minnesota Power's big industrial customers. Minnesota Power also owns the 25 MW Taconite Ridge Wind Energy Center, built on U.S. Steel property near the Minntac mine and in service since 2008.
Profile
- Pellet lines idled and restarted with demand
- Minntac's pellet lines are run to demand, which shows up directly in its electric load. In 2007 U.S. Steel idled Line 3 on January 30 to match the market, then announced in August that the line would return to full production the week of September 10 to cover higher demand at its steelmaking plants and a tubular expansion, adding about 550,000 tons of pellets for the rest of that year. U.S. Steel's spokesman said the smallest line is operated as needed depending on market conditions.
- Ownership, investment and direct-reduced iron
- In June 2022 U.S. Steel announced about $150 million to upgrade either Minntac or Keetac to make DR-grade pellets that feed direct reduced iron and hot briquetted iron supply for electric arc furnace mills. After Nippon Steel's $14.9 billion acquisition of U.S. Steel in 2025, the company said about $890 million of Nippon's pledged $11 billion in new investments would go to Minntac and/or Keetac, which together make up U.S. Steel's Minnesota Ore Operations. Details of where that spending lands had not been announced as of June 2026.
Facility
- Activity
- Taconite iron ore pellets for blast-furnace steelmaking
- Industry
- Manufacturing
- Site type
- Facility
- Operating status
- Operating
Grid connections
- Utility
- Minnesota Power (ALLETE)Reported
- Market
- MISOSite location
- Nearest substations
- Unnamed substation115 kV210 m
- Unnamed substation115 kV450 m
Related records
Timeline
- Jan 30, 2007
- Minntac Line 3 idled
Minntac to restart pellet line - Duluth News Tribune | News, weather, and sports from Duluth, Minnesota
- Aug 31, 2007
- Restart of Line 3 announced for the week of September 10
Minntac to restart pellet line - Duluth News Tribune | News, weather, and sports from Duluth, Minnesota
- Oct 11, 2016
- ALLETE announces five-year Minnesota Power agreement to supply Minntac and Keetac
Minnesota Power inks 5-year deal with U.S. Steel taconite plants - Duluth News Tribune | News, weather, and sports from Duluth, Minnesota
- Jun 28, 2022