How does water treatment affect the quality of mine drainage ?
Let’s assume the mine tailings contain sulfide 1 minerals that react with oxygen and water to produce sulfuric acid 1. Acidic mine drainage also dissolves metals 1 from the residual ore minerals remaining in the tailings. Treatment of mine drainage may simply neutralize acidity 2 by adding limestone (calcium carbonate). Neutralizing acidity will also remove many of the metals dissolved in the drainage water, but further chemical treatment that specifically removes toxic metals may be necessary. The end product of this treatment is a higher quality water that is no longer acidic and contains less dissolved metals and a sludge containing the metals removed by the water treatment process. If the levels of toxic metals are sufficiently high, the sludge may be considered a hazardous waste.
