Abstract

The effect ofl-cysteine in different concentrations on the bioleaching of Ni–Cu sulfide and marmatite were studied with a moderately thermophilic, sulfur-oxidizing bacterium, strain ofAcidithiobacillus caldus. X-ray diffraction (XRD) observations showed the change of bioleached solid residues and the effect ofl-cysteine on the surface charges of minerals. It was found that adding certain amounts ofl-cysteine to the leaching system of Ni–Cu sulfide largely enhanced the leaching rate, whilel-cysteine inhibited the bioleaching of marmatite byA. caldus. The mechanism ofl-cysteine interaction with mineral surfaces was studied by means of zeta potential determination and IR spectra.