A process for leaching a value metal from a base metal sulfide ore,
comprising the step of leaching the ore with a lixiviant comprising a
chloride, an oxidant and hydrochloric acid is disclosed. The leaching is
controlled, by use of low concentrations of hydrochloric acid and a redox
potential, to effect formation of hydrogen sulfide from the base metal
sulfide ore. The hydrogen sulfide is stripped from the leach solution,
thereby reducing the amount of sulfate generated in the leach to very low
levels. The leaching may also be conducted to limit the co-dissolution of
platinum group metals and gold with the base value metals. The leach
forms a value metal-rich leachate and a solids residue. The solids
residue may be subsequently leached to recover the platinum group metals
and gold. The value metal-rich leachate can be is oxidized and
neutralized to recover the value base metals. In an embodiment, the
chloride is magnesium chloride and lixiviant solution is regenerated.