CHEMICAL OXIDATION INTEGRATED INTO BIOLEACHING OF PYRITE AND CHALCOPYRITE USING IMMOBILIZED BIOMASS

Chemical oxidation of pyrite and chalcopyrite by ferric sulfate (Fe2(SO4)3) solution and biogenic ferric iron obtained by mixed culture of isolated thermotolerant Acidithiobacillus sp. 13Zn and Leptospirilum ferriphilum CC immobilized on natural carrierszeolite and shungite was studied. Oxidation rate of sulfide minerals was estimated by the decrease of Fe3+ (oxidant) and increase of Fe2+ ions in the solution. It was revealed that chemical oxidation of chalcopyrite by biogenic ferric iron occurred 2-3 times more intensively than that by Fe2(SO4)3 solution. Pyrite oxidation rate by biogenic ferric iron was twice higher than that by chemical ferric iron solution. It was shown that the treatment of pyrite and chalcopyrite by biogenic ferric iron allows to increase on average 1.5-2times the bioleaching of iron from pyrite and iron and copper from chalcopyrite by the associations of iron and sulfur oxidizing bacteria.