Behaviour of Anode Impurities in Copper Electrorefining

Effect of sulfur, arsenic and oxygen

Abstract

The behaviour of sulfur and oxygen in copper electrorefining has been investigated. The form of anode slime and the dissolution state of anode surface after electrolysis as well as the effect of dissolved oxygen in electrolyte have been revealed. It was clarified that 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_1.96S particles in the matrix remained on the surface, thus forming the compact layer of anode slime and caused the anode to passivate very sensitively. In the case of high oxygen containing anode, Cu_1.96S particles were coasened and fell off the anode surface, and the anode passivation was not observed. The anode passivation was greatly accerelated with increasing current density, and it was unaffected by the concentration of dissolved oxygen in the electrolyte.
The anode containing sulfur, arsenic and oxygen was also investigated in termes of the form of anode slime and the anode passivation. On the electrolysis of the anode with high arsenic content, the fluffy slime of Cu₃ As was filled up in among the Cu_1.96S particles and was occured the anode passivation with great facility. Copper anode of low arsenic content did not passivated since the slime layer tended to fall.