A cleaner way to mine gold, without the cyanide
Mining gold has long carried an ugly secret: cyanide, the poison used to separate the metal from its ore, and the arsenic often left behind in the waste. A Quebec company, Dundee Sustainable Technologies, has found a gentler path. Their CLEVR process swaps cyanide for a recycled, closed loop mix that draws gold from ore at room temperature in about two hours, rather than a day and a half. Nothing toxic is released, and the chemicals are used again and again.
They have taken on the arsenic too. A second process, called GlassLock, locks it away by turning it into a stable, inert glass that can be safely removed. In trials on a project in Alaska, the two methods together recovered 95 percent of the gold while trapping 98 percent of the arsenic, cutting the waste's toxicity almost to nothing. It is a quietly hopeful sign that even one of the dirtiest industries can be cleaned up.