A method of biooxidizing
sulfide minerals in a nonstirred
bioreactor is provided. According to the disclosed method, a concentrate of
sulfide minerals is coated onto a substrate, such as coarse ore particles,
lava rock, gravel or rock containing mineral
carbonate as a source of CO2 for the biooxidizing
bacteria. After the
sulfide minerals are coated onto the substrate, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The
sulfide minerals are then biooxidized to liberate the
metal value of interest. Depending on the particular ore deposit being mined, the sulfide mineral concentrates used in the process may comprise sulfide concentrates from
precious metal bearing
refractory sulfide ores or they may comprise sulfide concentrates from
metal sulfide type ores, such as
chalcopyrite, millerite or sphalorite. The distinction being that in the former, the
metal of interest is a
precious metal occluded within the
sulfide minerals, whereas in the latter, the metal to be recovered is
copper,
nickel or
zinc and is present as a metal sulfide in the sulfide concentrate.