REFINING OF METALS
The metals produced by various reduction processes described above are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.
In this process, the impure metal is used as anode and strip of pure metal is used as a cathode. The solution of metal salt is used as an electrolyte. On passing the current through the electrolyte, the pure metal from the anode dissolve into the electrolyte. An equivalent amount of pure metal from the electrolyte is deposited on the cathode. The soluble impurities go into the solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.