Behaviour of anode impurities in copper electrorefining: Effect of sulfur, arsenic and oxygen

The behavior of sulfur and oxygen in copper electrorefining has been investigated. The form of anode slime and the dissolution state of the anode surface after electrolysis as well as the effect of dissolved oxygen in the electrolyte have been revealed. The anode passivation occurs depending on the concentration of oxygen and sulfur in the anode. In the case of anode copper with low oxygen content, the fine Cu_1.96 S particles in the matrix remained on the surface, thus forming the compact layer of anode slime and caused the anode to passivate sensitively. In the case of a high oxygen containing anode, Cu_1.96S particles were coarsened and fell off the anode surface and passivation was not observed. The anode passivation was accelerated with increasing current density, and was unaffected by the concentration of dissolved oxygen in the electrolyte. The anode containing sulfur, arsenic and oxygen was also investigated in terms of the form of anode slime and anode passivation. On the electrolysis of the anode with arsenic content, the fluffy slime of Cu₃As was filled in among the Cu_1.96 S particles. A copper anode of low arsenic content did not passivate since the slime layer tended to fall.