Electrolytic refining is a technique that is used for the extraction and purification of metals that are obtained by refining methods. The impure metal is used as an anode and the pure metal is used a cathode. Soluble salt from the same metal is used an electrolyte. When an electric current is passed, pure metal gets deposited at the cathode and the impure metal gets dissolved from the anode. Impurities from the metal gets collected below the anode and is known as anode mud.
In the electrolytic refining impurities such as gold, silver, platinum group metals, arsenic, selenium, and tellurium are recovered.
Example of Electrolytic Refining
Electrolytic refining of copper is an example of electrolytic refining.
The image consists of electrolytic tank with acidified copper sulphate as electrolyte. A thin strip of pure copper metal is used as cathode. A thick strip of impure copper metal is used as anode.
Following are the reactions that take place at cathode and anode respectively: