A method of improving
metal leach
kinetics and
recovery during atmospheric or substantially atmospheric leaching of a
metal sulfide is disclosed. In some embodiments, the method may comprise the step of
processing a
metal sulfide concentrate in a reductive activation circuit 220 that operates at a first
redox potential, to produce a reductively-activated metal
sulfide concentrate. The method may further comprise the step of subsequently
processing the activated metal sulfide concentrate in an oxidative leach circuit 240 to extract metal values. In some disclosed embodiments, reductive activation steps and / or oxidative
dissolution steps may employ mechano-chemical and / or physico-chemical
processing of particles or agglomerates thereof. Reductive activation may be made prior to
heap leaching or bio-leaching operations to improve metal extraction. Systems for practicing the aforementioned methods are also disclosed.