ABSTRACT OF THE DISCLOSURECuprous sulphate solutions, suitable for thermal orelectochemical disproportionation to yield copper, areobtained by dissolving copper sulphites, such as Chevreul'ssalt or cuprous ammonium sulphite, in acetonitrile-wateror 2 hydroxycyanoethane-water mixtures, preferably inthe presence of cupric sulphate. This discovery is capableof a number of applications, one of which is the recoveryof copper from chalcopyrite by the following five steps.An oxidising roast of chalcopyrite such as to produceeither cupric sulphate and/or copper oxide, leaching ofcupric sulphate from the calcine, precipitation of Chevreul'ssalt and/or other copper sulphites with a soluble salt ofsulphurous acid, including bisulphites, dissolution of thecopper sulphite as cuprous sulphate, using cupric sulphatein an acetonitrile-water solution as oxidant; precipitationof pure copper by thermal disproportionation of the cuproussulphate solution. Acetonitrile and acidic cupric sulphatesolution may be recycled. Advantages over conventional-2-processes, much as roast, leach-electrowin, or smelt,convert, electrorefine, include lower cost, lower energycomsumption, sulplur removal as ammonium sulphate or gypsum,rather than as sulphur dioxide, and rapid throughput. Thenett reaction is:2CuFeS2 + 4H20 + 2 02 + 8NH3 + 2Cu + 4(NH4)2SO4 + Fe203,
展开▼
