Alot of what makes coal dirty isn't coal at all, but the rock mixed in with it. The rock contains sulfur, a factor in acid rain, as well as toxic heavy metals such as lead. To rid coal of rock, miners often dump it into a slurry of water and an iron ore called magnetite. The clean chunks float on the slurry, while the rock-laden ones sink. So as not to waste the chunks that sink, they're broken into pieces, and the process is repeated. But if the pieces get too tiny, they all sink.
That's where Custom Coals Corp. in Carefree, Ariz., comes in. Using a technique pioneered by co-founder James Kelly Kindig, the company makes its grains of magnetite much smaller, so even minute grains of coal can be recovered. The bottom line: cleaner coal. The Energy Dept. has agreed to put up half of the $76 million cost of a pilot coal-cleaning plant that Custom Coals hopes to build in Somerset County, Pa. And with the help of Chase Manhattan Bank, Custom Coals is seeking funding from international aid agencies and private industry to build two cleaning plants for about $120 million next to coal mines in Poland.