BIOLEACHING OF A SULFIDE-Cu, Zn MINERAL BY Acidithiobacillus sp., ISOLATED FROM ACID MINING DRAINAGE, LA LIBERTAD (PERU)

Abstract

Acid mine drainage (AMD) is a potential source for the isolation of microorganisms with the ability to leach sulfur ore; for this reason, its use of these effluents allows the choice of sustainable technologies and improves the recovery of metals of commercial value. The objective of this research was to bioleach a sulfur ore by Acidithiobacillus sp., isolated from an AMD of La Libertad (Peru). AMD samples were enriched in 100 ml of 9K medium at pH 2.5 at 23 ± 2 °C for 14 days and a pure microbial culture was isolated in 9K-agarose medium. It was characterized by Gram stain and its physiology using inorganic media (elemental sulfur, ferrous ion and sodium thiosulfate), obtaining typical characteristics of Acidithiobacillus sp. Its ferrous ion oxidation rate was determined at different pHs (1.5, 2.5 and 3.5) and its bioleaching capacity of a sulfur ore, obtained from the Sayapullo district - Peru, for 25 days at 400 rpm with pH 2.5. The results showed a higher ferrous ion oxidation rate of 50.13 ± 5.4 mg/L.h at pH 2.5 and presented a higher recovery of copper (Cu), zinc (Zn) and gold (Au) with 52, 54 and 30%, respectively, with a solution iron 31%. Therefore, it is shown that Acidithiobacillus sp. obtained from AMD of La Libertad (Peru), it can be used as an alternative to recover metals of commercial value by bioleaching sulfur ore.