Study On Passivation Layer Of Chalcopyrite In Bioleaching Process

The bioleaching copper has some advantages compared with the traditional copper smelting, but the passivation leading to the low leaching rate limits the application and development of bioleaching copper as bottle neck. Thus the research of biooxidation passivation has its special meaning and real value.The paper is focused on the refractory chalcopyrite in low grade. The bacterial hydrometallurgy is used to leach copper by HQ0211bacteria. The paper is consisted of following parts. It is studied for the optimal growth conditions of experimental bacteria, the influencing factors change of copper leaching rate, the bacterial adsorption law on the surface of chalcopyrite in the bioleaching process and XPS analysis for the passivation layer on the surface of chalcopyrite.The results show that the optimal initial pH is1.5for the growth of HQ0211bacteria. The leaching rate increases when the grain size of chalcopyrite is small, the pulp concentration is5%and pH value is1.4-1.6. There are some laws for the adsorption of HQ0211bacteria. In the initial phase, the bacterial adsorption quantity increases along with time. In the stationary phase, over90%bacteria are adsorbed on the surface of ores. When the leaching time is extended, the bacterial activity descends, the nutriment decreases and the toxicant increases. After the stationary phase, the adsorption quantity decreases. XPS shows that Fe2+is leached prior to Cu2+in the process of chalcopyrite leaching. The polysulfide with higher copper and lower iron is produced on the surface of ores. The polysulfide copper is oxidized and cumulated in the oxidation process. The jarosite is produced to form passivation layer on the surface of chalcopyrite. The passivation of chalcopyrite is the combined action of polysulfide copper, elemental sulfur and jarosite. The results provide basis for the improving copper bioleaching rate of chalcopyrite.