INDIRECT BIOLEACHING OF COVELLITE BY THIOBACILLUS THIOOXIDANS WITH ANOXIDANT AGENT

High copper extraction by the action of Thiobacillus thiooxidans (T.t. ) on covellite in presence of iron(III) is explained by indirect mecha nism, in which T.t. only oxidizes the layer of sulphur that covers the sulphide surface allowing sulphide oxidation by iron(III). In culture s on elemental sulphur with iron(III) T.t. is not able to use iron(III ) as an acceptor of electrons in sulphur oxidation; iron(III) only oxi dizes those intermediates which were generated in the aerobic oxidatio n of sulphur.