Bio-oxidation of a high-sulfur and high-arsenic refractory gold concentrate using a two-stage process

摘要

To improve the oxidation rate of high-sulfur and high-arsenic refractory gold concentrate (HGC), a two-stage chemical-biological oxidation approach, which contained a high-temperature chemical oxidation stage (ferric leaching stage) and a subsequent biological oxidation stage with mesophiles, was used in this experiment. The surface analysis of pure arsenopyrite using scanning electron microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) indicated that the surface lattice structure was partly disrupted after chemical oxidation; as a result, the subsequent biological oxidation rate during the second stage improved significantly. The extraction levels of Fe, As and S were 49.8%, 50.4% and 51.0%, respectively, in the normal biological oxidation system, while the values increased to 63.3%, 64.2% and 63.3%, respectively, following the two-stage process. Accordingly, the recovery rate of gold increased by 16.8% using the two-stage process compared to that of the one-stage biological oxidation approach.