The U.S. steel industry gets most of its iron ore from the vast ranges of northern Minnesota, where the rich, rust-like dust can be shoveled up from the ground. But by 1970, or sooner, the open-pit ranges of Minnesota will be scraped bare.
Beneath the Minnesota ground, however, there is a low-grade ore called taconite, which has never been developed—for lack of a cheap, practical way to extract it. Several years ago, researchers at the University of Minnesota perfected a method of crushing the rock, extracting the ore by magnets and compressing it...
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