Bioleaching of marmatite flotation concentrate by Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans

Bioleaching of marmatite flotation concentrate by Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans was investigated at 35 degreesC, the initial pH value of 2.0 on an orbital shaker with 160 min(-1) over 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 of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in mixed cultures are more efficient in the oxidation of marmatite.