Zinc recovery in an air-lift bioreactor by isolated Leptospirillum ferrooxidans

CHIACCHIARINI P,; GIAVENO A,; LAVALLE L.; DONATI E.

HYDROMETALLURGY (AMSTERDAM)

Año: 2007 vol. 89 p. 117 - 126

0304-386X

Bioleaching of low-grade complex sulfide ores from La Silvita and La Resbalosa (Patagonia Argentina) in a reverse flow airlift reactor by a native strain of Leptospirillum ferrooxidans (Lf-LS04) were carried out at an initial pH of 1.8, with a particle size of -74 mm, pulp density of 1% and a superficial air velocity of 0.01 m s-1. Copper, zinc, and total soluble iron were determined by absorption atomic absorption spectrophotometry. High recoveries of copper and zinc were obtained after bioleaching. Solid residues were recovered by centrifugation and were analyzed by X-ray diffraction. In both of the ores studied, the kinetics of the bioleaching process were analyzed for zinc by applying the shrinking core-product layer diffusion model. Diffusion was found to be rate limiting due to the formation of an insoluble product layer (elemental sulfur, anglesite and ferric iron precipitates) as well as to the presence of an unreacted layer of gangue minerals (quartz, feldspar).