Your article "Tails of Woe" (11 November, p 46) concerning environmental disasters caused by dumping mine tailings is very topical given the recent collapse of a dam wall at a gold mine in Romania.
However, a simple final flotation step could remove the remaining sulphides (mainly pyrite) prior to tailings being discharged. This step produces a benign silicate waste, which does not cause pollution because it contains insufficient sulphide to generate acid. The pyrite concentrate can be further treated or returned to the mine as backfill. Wastes containing cyanide can easily be treated to make the toxic chemicals harmless prior to discharge.
I could not let your article pass without attempting to present the enlightened and responsible position of the mining and metallurgical industry today.
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