The Electrorefining of Copper from a Cuprous Ion Complexing Electrolyte

Abstract

The energy saving potential and refining capabilities of three copper(I)/electrolyte systems for electrowinning copper were compared experimentally. The alternative electrolyte systems studied were copper(I)/acidic chloride, copper(I)/acetonitrile and sulfuric acid, and copper(I)/ammonia solutions. These were compared to the conventional copper(II)/sulfuric acid electrolyte. All the alternative systems demonstrated at least some potential for saving energy when run at deposition rates equal to the conventional process. The chloride electrolyte showed the greatest energy saving potential, about 70%, and the ammonia electrolyte showed the least, about 25%. All, however, exhibited performance problems, primarily with regard to inadequate separation of impurities. A preliminary capital cost estimate made for the copper(I)/chloride system showed that, for it to be cost competitive (that is, a reduction of capital cost of about 15–20%) with the conventional electrorefining process, the refining cells would have to be operated at a current density of about 25–30 mA/cm2. At this current density, the estimated energy saving potential for the copper(I)/chloride system was still about 50%.