Cathodic refining in molten salts: Removal of oxygen, sulfur and selenium from static and flowing molten copper

The removal of nonmetallic impurities, including oxygen, sulfur and seleniu m, from molten copper (cathode) was achieved by constant voltage electrolys is in molten BaCl2 and CaCl2 alone, or the eutectic mixture of the two at t emperatures slightly higher than the melting point of copper. At the applie d voltages (2.1 similar to 2.9 V), the cathodic refining occurred without p rovoking the decomposition of the chloride salts, demonstrating the cathodi c ionization of impurities to be responsible. Further evidence supporting t his mechanism came from SEM, EDX and preliminary voltammetric studies. To i ncrease the mass transfer of the impurities in the molten copper during the refining process, a novel recessed channel electrode (RCE) was used. The r esults have demonstrated the feasibility and efficiency of using this techn ology in terms of space, time and yield of product, offering considerable a dvantages over a simple electrorefining cell.