BIOLEACHING OF SULFIDES UNDER APPLIED POTENTIALS

The influence of applied DC potentials on the activity and growth of Thiobacillus ferrooxidans, as well as on the dissolution behavior of some base metal sulphides is discussed with reference to bioleaching. Selective bioleaching of zinc from sphalerite could be achieved under an applied potential of -500 mV (saturated calomel electrode) from binary mineral mixtures containing the zinc mineral and chalcopyrite or pyrite. On the other hand, bioleaching of pyrite and chalcopyrite was found to be enhanced under positive potentials of +400 mV and +600 mV, respectively. Probable mechanisms in the electrobioleaching of sulphides are examined with respect to galvanic, microbiological and applied potential effects.