Effect of initial pH on chalcopyrite oxidation dissolution in the presence of extreme thermophile Acidianus manzaensis

The influence of initial pH on the chalcopyrite oxidation dissolution at 65 °C was investigated by bioleaching and cyclic voltammetry experiments, and the oxidation products were investigated by XRD and Raman spectroscopy. Bioleaching results show that chalcopyrite dissolution rate increases with the decrease of the initial pH in chemical leaching, while the influence of initial pH on bioleaching is on the contrary. The presence of Acidianus manzaensis does not promote chalcopyrite dissolution under initial pH 1.0, which mainly results from serious inhibition of high acidity to the growth of Acidianus manzaensis. Electrochemical experiments results show that anodic oxidation currents of electrolyte with or without Acidianus manzaensis both increase with the increase of initial pH, and covellite and sulfur are detected on the electrode surface. The results confirm that chalcopyrite dissolution in chemical leaching is under the combined action of oxidation and non-oxidation of proton, with conversion of chalcopyrite to covellite and elemental sulfur.