Abstract:Bioleaching of marmatite flotation concentrate by Acidithiobacillusferrooxidans and Leptospirillum ferrooxidanswas investigated at 35℃, the initial pH value of 2.0 on an orbital shaker with 160 min-1over a period of 10 days. Experimental results indicate that the adapted strains increase markedly the dissolution rate and the leaching ratio of marmatite. Pulp density also affects the bioleaching of marmatite. Massive elemental sulfur and jarosite form during the leaching process in the systems inoculating the adapted strains in pure and mixed cultures; and acid product is enhanced, which decreases the pH below to 2.0 in latter leaching period. Marmatite preferentially dissolves during the bacterial leaching of complex sulfides. Compared with the pure cultures of original and adapted strains, the adapted strains ofAcidithiobacillus ferrooxidansandLeptospirillum ferrooxidansin mixed cultures are more efficient in the oxidation of marmatite.

Key words: marmatite; bioleaching;Acidithiobacillus ferrooxidans; Leptospirillum ferrooxidans