In electrolytic refining the impure metal is made as anode and the pure metal is made as cathode.
Principle of electrolytic refining
Electrolytic refining is a way of purifying impure metals by using electricity. The anode in this process is impure metal, while the cathode is a strip of pure metal. A soluble salt of the same material as the electrolyte is used to make a solution.
When an electric current is transmitted, metal ions from the electrolyte are deposited as a pure metal in the cathode, and the impure metal from the anode dissolves in the form of ions into the electrolyte. Below the anode, the impurities of metals are collected, and it is known as mud anode.