A low temperature chlorination–volatilization process for the treatment of chalcopyrite concentrates

Chlorination of two chalcopyrite concentrates with Cl2+N2 was investigated under isothermal conditions in the temperature range of 20–750°C using boat experiments. The effects of gas flow rate, chlorine content of the gas mixture and residence time on the reaction rate were also investigated. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and chemical analysis are used for the physico-chemical characterization of the reaction products. The chlorination of chalcopyrite concentrates started at room temperature generating chlorides of Cu, Pb, Zn, Fe, and S. The reaction of chlorine with sulfides is almost complete at about 300°C and the overall reaction is exothermic. At this temperature, the valuable metal chlorides were concentrated in the chlorination residues, while those of iron and sulfur were volatilized. A flow sheet is proposed for the selective chlorination of chalcopyrite concentrates at low temperatures. Such flow sheet could be considered as an attractive route for the sulfide concentrates’ treatment without SOx emissions. It could be also regarded as energy saving with respect to the classical pyrometallurgical routes.