Electrolytic refining is a process used to refine impure metals, such as copper, zinc, tin, lead, nickel, silver, and gold, to obtain pure metals. In this process, a solution of the metal salt is used as an electrolyte, and a thick block of impure metal is made anode, while a thin strip of the pure metal is made cathode. A water-soluble salt of the metal to be refined is taken as an electrolyte. On passing electric current, impure metal dissolves from the anode and goes into the electrolytic solution, while pure metal from the electrolyte deposits on the cathode. The soluble impurities present in the impure metal go into the solution, whereas the insoluble impurities settle down at the bottom of the anode as anode mud.

For example, copper is usually mined from coal, known as blister copper, which is about 98 to 99% pure. However, the electro-refining process can easily make it 99.95% pure, which makes it a good product to be used in electrical components. The process of electrolytic gold refining uses hydrochloric acid as an electrolyte, with the cathode made of a thin sheet of gold and the anode made of a gold alloy. When ion transfer takes place, pure gold with a higher purity rate is transferred.

In summary, electrolytic refining is a process used to refine impure metals to obtain pure metals. It involves using a solution of the metal salt as an electrolyte, with a thick block of impure metal made anode and a thin strip of the pure metal made cathode. On passing electric current, impure metal dissolves from the anode and goes into the electrolytic solution, while pure metal from the electrolyte deposits on the cathode.