Iron Range 101: What is taconite?


Taconite is a low-grade iron ore. Originally thought to be of little value, taconite was considered overburden (waste) in the days when high grade iron ore was mined. The iron content, magnetite, is only 20- 30% compared to 50 – 60 % iron content in red ore.  Red ore is also referred to as direct shipped ore because it can be shipped without processing. Taconite needs to be crushed and processed into pellets before it can be shipped to steel mills.

This is the first in an on-going series explaining and exploring the unique history, people, culture and institutions of Minnesota’s Iron Range.

Geologist Peter Mitchell discovered the first vein of taconite in 1870 while searching for gold and silver.  This large vein located near Babbitt stretched 1 1/2 miles wide by 12 miles long. In the early 1900’s, University of Minnesota Mines Experiment Station Professor E.W. Davis found a way to extract the iron from the taconite rock and form a concentrate. While the first commercial taconite pellets weren’t produced until 1955,  the birth of the taconite industry occurred in 1922 with the construction of a taconite processing plant in Babbitt. However,  the method of extracting and upgrading taconite into pellets was not yet cost-effective and the Mesabi Iron plant closed just two years later because it could not compete with the other ores being mined. Davis, the ‘Father of Taconite’ continued to perfect the process of mining and refining taconite over the next four decades.

As the supplies of high-grade ore dwindled in the years preceding World War II, alternative sources of iron (and for the Iron Range, new industries) were sought and our attention once again turned towards taconite. Minnesota Governor Harold Stassen stepped in to assist those efforts by authorizing a unique new state agency funded solely by a portion of the iron ore tax. The mission of the Iron Range Resources and Rehabilitation Commission (predecessor to the Iron Range Resources and Rehabilitation Board) was to diversify the depressed Iron Range economy away from the depleted red ore.  Ignoring experts who said it couldn’t be done,  the agency spent over $2.5 million to fund Dr. Davis’ research to find a more cost effective method of refining taconite. The gamble paid off and Reserve Mining Company was formed specifically to take advantage of this new technology. Taconite was transported from the Peter Mitchell mine near Babbitt to the processing facility in the new company town of Silver Bay.  In April 1956, the first commercial-grade taconite pellets were shipped out on the C. L. Austin.

The commercial production of taconite pellets revolutionized the steel industry and revitalized the economy of the Iron Range. Seeing the success of Reserve Mining, other mining companies followed suit and by the 1970’s, there were eight taconite plants operating in northeastern Minnesota. United States Steel’s Minnesota Taconite (MinnTac) in Virginia is the largest taconite processing facility in the world.

This modern process for extracting iron ore from taconite and refining concentrate into pellets is a direct result of Dr. Davis’ research funded by the IRRRB:

First,  holes are drilled and the taconite ore is blasted out of the ground. It is transported to the processing plant in huge trucks that can hold up to 240 tons of taconite. Placed into  crushers, the taconite is crushed, mixed with water and ground into a fine powder. Next it goes to the separators where the iron ore is separated from the taconite using strong magnets; this is the concentrate. The remaining waste rock is dumped into tailings basins.

Taconite pellets are made by rolling the concentrate with clay inside rotating cylinders called agglomerators.  These little balls the size of marbles are dried and baked to become the familiar hard pellets that kids on the Range quickly learn will leave orange stains on skin and clothing when handled. The pellets, which have an iron content of 65%,  are melted down into steel at steel mills.

Ironworld (temporarily known as the Minnesota Discovery Center) in Chisholm has a great year-round exhibit where one can follow the process described above.  The Hull-Rust Mahoning Mine View in Hibbing, over-looking the largest open pit mine in the world, is open mid-May through September.