Allan Ang

Mass transport of copper ions to the cathode during the electrowinning of copper is important in determining the optimum current density in order to achieve deposits of acceptable physical and chemical quality. The results of pilot scale tests using full size cathodes and anodes (both lead-calcium-tin and titanium mixed metal oxide, MMO) will be described. In these tests, silver ions have been used as a tracer in order to determine local mass transfer coefficients to 16 sections of each cathode. The results have shown that mass transfer is slightly higher at the top and bottom of the cathode and that the distribution is more uniform with MMO anodes than with conventional lead alloy anodes. The results agree quantitatively with previously published data obtained using half width electrodes. Measurement of the mass of each section has also been used to establish the current distribution over the surface of the cathodes. In addition, the reduced cell voltage obtained with the MMO anodes has been quantified as have the voltage drops at the contact of the anode header bars with the busbar.