China Nonferrous Metallurgy

Gold minerals in high arsenic and high sulfur gold concentrate are coated with arsenopyrite (As₂O₃) and pyrite (FeS₂), and the leaching rate of direct cyanide leaching is low. The pretreatment technology of high arsenic and high sulfur gold concentrate has been the focus of research attention. In this paper, Tajikistan gold concentrate with high arsenic and high sulfur is taken as the research object. On the basis of thermogravimetric analysis and thermodynamic analysis, a two-stage roasting method is used for pretreatment to remove most of the harmful impurities such as arsenic, sulfur and organic carbon, and the process parameters are optimized. The effects of additives, calcination temperature and time on the removal rate of carbon, sulfur and arsenic in gold concentrate were investigated. Based on the phase analysis of the final calcination product, the roasting-cyanide leaching test was carried out, and the main conclusions were obtained as follows. The first-stage roasting was carried out in a low oxygen atmosphere without additives, and the optimum process parameters were roasting temperature 500~550℃ and roasting time 2h. The second-stage roasting was performed in an oxygen-rich atmosphere, and the optimum process parameters were roasting temperature 650~700℃ and time 2h. Under the above optimal process parameters, the removal rates of carbon, sulfur and arsenic were 91.16%, 96.93% and 92.52%, respectively, and the gold leaching rate reached 95.30%. Compared with the direct cyanide leaching, the gold leaching rate is increased by 20%, which realizes the high value utilization of resources to a certain extent, and provides a technical basis for efficient gold extraction from refractory gold concentrate.