What are the Reactions of Anode and Cathode in the Gold Electrowinning Process?

What are the Reactions of Anode and Cathode in the Gold Electrowinning Process?

Electrowinning, also called electrorefining or electroextraction, is the electrodeposition of metals from their ores that have been put in solution or liquefied. Electrowinning is an important technology that allows the purification of non-ferrous metals in an economical and straightforward step.

Electrowinning involves the application of electrical current between two electrodes immersed in a metal bearing solution (known as electrolyte). Under the correct conditions, the dissolved metal will plate onto the negative electrode (cathode). Because metal deposition rates are related to the available surface area, maintaining properly working cathodes is important.

In the gold electrowinning process, gold is electrolytically displaced from the alkaline cyanide solution (pregnant eluate) and deposited on the cathode surface. Once the cathodes are laden with the required amount of gold they are removed from the cells for calcining followed by smelting to produce gold bullion.

The anode does not collect gold but is necessary for the current to flow, completing the electrical circuit within the cell. It is important that the eluate has a high pH, as the anodes will corrode at a pH of less than12.5. Oxygen gas produced by the oxidation of water is the main reaction occurring at the anode.