Electrolytic Methods Used in Refining Processes of Gold and Other Precious Metals
Electrolysis is an electro-chemical process where an electrical current stream is flowing between two electrodes and through an electrolyte. This process involves the transfer of metal ions through the ionised electrolyte solution, depositing positive ions on the cathode and negative ions on the anode.
Most metals produced by electrolysis are exceptionally pure, and gold and precious metals make no exception. Electrolytic processes for gold and other precious metals refining usually provide the most cost-effective method of separating these metals from the slag, or gangue.
The Electro-refining Process
There are two main types of electrolytic processes, called electro-refining and electro-winning. Both processes use direct electrical current whereby pure metal is deposited at the cathode. Electro-refining is the preferred method as an electrolytic process for gold and other precious metals.
The electro-refining process uses a melted solid mixture of impure metal as the anode and a thin sheet of metal as the cathode. When the electrodes are immersed in an electrolyte and an electrical current is applied, pure metal is deposited onto the cathode through the dissolution and transfer of that metal from the anode.
Electrolytic Processes for Gold and Other Precious Metals
The electrolytic refining process for gold uses hydrochloric acid as the electrolyte. The anode is made of gold alloy and the cathode is usually a thin sheet of high purity gold. The electric current ionises the electrolyte and transfers dissolved gold from the anode to the cathode, thereby increasing the purity of the gold at the cathode.
This refining process is known as the Wohlwill process. Silver and other precious metals can be refined using the same electro-refining technique. There is clear evidence that electrolytic processes for gold and other precious metals produce metals of high purity.