Doe Run trial runs a breakthrough wet chemical process that promises greener lead refining

May 01, 2010 | 04:20 AM | Tatyana Shumsky

Lead miner Doe Run Co. hasn't turned lead into gold quite yet. But Dave Olkkonen, manager of research and technical development, has come close, helping to successfully adapt the electrowinning refining process to lead concentrates.

"The technology we're talking about is very similar to what microchips have meant to telecommunications and computers. It's that significant of a technological advance for the lead industry," Olkkonen said.

Traditional lead smelting can be a dirty business. Lead concentrates are mixed with coke and various other raw materials, like silica, limestone or soda ash, and fed into a red-hot furnace where lighter impurities like sulfur are burned off. The energy-intensive process is not fully efficient, as it doesn't draw 100 percent of the lead out of the concentrate mixture and allows lead particles to escape into the air.

More importantly, traditional lead refining is environmentally hostile. Sulfur dioxide is released in large quantities and must be converted to sulfuric acid, and lead emissions leak into the atmosphere—lead particles can escape even the most high-tech installations—pollute land and water. Then there is the slag, a glass-like by-product that's a mix of silica and heavy metal compounds that is hazardous to release into the environment, forcing lead refiners to simply store it.....

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