RECOVERING COPPER AND ZINC FROM COMPLEX SULFIDES

摘要

A process for treating thermally activated metal sulfides containing copper, iron and zinc for separate recovery of zinc as zinc sulfide in which the metal sulfides are subjected to a two-stage countercurrent acid leach for the formation of copper sulfide containing acid leach residue and ferrous sulfate solution. The second-stage acid leach is performed in two steps; the first step is operated at a relatively high pulp density and high acid concentration for iron and zinc extraction, the resulting slurry diluted, and the second step is operated at a relatively low pulp density and low acid concentration for dissolution of precipitated ferrous sulfate and precipitation of any dissolved copper values by H2S. The diluent solution for the slurry from the second-stage first step preferably is generated sulfuric acid solution from a jarosite precipitation and iron and zinc-containing solution from a subsequent activation leach. Zinc in solution from the acid leach and activation leach is precipitated as zinc sulfide in substantially pure form.