Anodes are placed in the refinery tank house in large cells containing acidified copper sulphate solution. Thin sheets of copper, called "starter sheets", are suspended between the anodes to act as cathodes. An electrical current is passed directly through the circuit, causing the copper ions to migrate and plate out on the cathode through a process of electrolysis.
The resulting cathodes are 99.99% pure and are either sold in this form or sent to the rod casting plant. The precious metals present in the anodes - which include low concentrations of gold, silver, platinum and palladium - are not transferred in the electrolytic refining process. Rather, they are collected as anode slimes for sale to overseas refineries. Nickel is recovered from refinery electrolyte by means of a selective ion exchange process, before crystallizing, packaging and selling it as nickel sulphate hexahydrate.
At Palabora, beneficiation is taken further than in the usual copper smelter or refinery operation. The majority of cathode production is re-melted in a shaft furnace and cast into wire rod of various diameters for sale to South African producers of copper wire and cable.