Copper from Copper Concentrates Via Solutions of Cuprous Sulfate in Acetonitrile -Water Solutions

Chalcopyrite can be converted to pure copper by the following five steps. An exothermic sulfation roast of chalcopyrite; leaching of cupric sulfate from the calcine with dilute acid; precipitation of Chevreul's salt and or other copper sulfites with ammonium sulfite or precipitation of crude copper by autoclaving ammonium sulfite and cupric sulfate at 150°C; dissolution of Chevreul's salt, or the crude copper, as cuprous sulfate, using acidic cupric sulfate in an acetonitrile-water solution as oxidant; precipitation of pure copper by thermal disproportionation of the cuprous sulfate solution. Acetonitrile and acidic cupric sulfate solution recycle. Advantages over conventional processes include lower cost, lower energy consumption as waste heat, sulfur removal as ammonium sulfate or gypsum, rather than as sulfur dioxide and rapid throughput. The net reaction is: 2 CuFeS2 + 4H20 + 15/2 02 + 8 NH3?2Cu + 4 (NR4)2 SO4 + Fe2O3