Taconite tailings in aggregate

Byproducts from the taconite pellet-making process in Minnesota have been piling up for decades, but research has found that these tailings could be a marketable commodity.

Researchers at the Natural Resources Research Institute (NRRI) of the University of Minnesota have been conducting extensive studies on the marketability of taconite waste.

The most likely use for coarse taconite tailings is in roadbed aggregate, an increasingly valuable commodity in metropolitan areas. It takes around 20,000 tons of aggregate to make a 1-mile stretch of 4-lane highway, and in Minnesota tailings are a proven aggregate in road building.

“There’s increasing demand for construction aggregate because of development, but development also keeps gravel pits and quarries from expanding,” says NRRI researcher Larry Zanko.

People don’t often think of how extensively aggregate or gravel is used. In Minnesota alone, 51 million tons of aggregate are used in Minnesota each year. Building one new home requires some 120 tons of aggregate.

Enter taconite tailings. EVTAC Mining in Eveleth, Minn., has 37 years’ worth of taconite byproduct on hand. And there are four other western Mesabi Range taconite plants operating in Minnesota.

NRRI researcher Julie Oreskovich says the tailings have received considerable use in northern Minnesota road reconstruction projects, most recently as an aggregate in Highway 169, between Virginia and Chisholm.

Zanko says the potential for marketing tailings as aggregate is being evaluated beyond Minnesota. Currently, researchers are investigating viable transportation options. The full results of their study will be published in spring of 2004.

— The preceding is from an information bulletin published by the Natural Resources Research Institute, based in Duluth, Minn.