EFFECT OF OPERATING-CONDITIONS ON ANODE PASSIVATION IN THE ELECTROREFINING OF COPPER

The effect of various process variables on anode passivation in copper electrorefining was investigated by combining conventional electroche mical techniques, laser-based visualization, and digital image process ing in a laboratory scale copper electrorefining cell. High current de nsity operation causes early anode passivation; in the range of 0.23 t o 1.50 kA m(-2), the effect of current density on the onset of passiva tion was found to be constant. The higher the temperature the longer t he time required for the onset of anode passivation. When the electrol yte is circulated, anode passivation occurs earlier than in the absenc e of circulation, but the effect also depends on the direction of circ ulation.