Both quicklime and hydrated lime are widely used in the flotation or recovery of non-ferrous metals, including copper, zinc, nickel, and lead-bearing ores.
Lime is used extensively in the recovery of gold and silver. Ores, either run of mine, milled, autoclaved, or roasted are combined with lime and a cyanide solution. The cyanide dissolves the gold and silver. Lime maintains proper pH in the cyanide solution, keeping it in the liquid phase and preventing the formation of hydrogen cyanide gas and its loss into the atmosphere.