Refining (metallurgy)

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In metallurgy, refining consists of purifying an impure metal. It is to be distinguished from other processes such as smelting and calcining in that those two involve a chemical change to the raw material, whereas in refining, the final material is usually identical chemically to the original one, only it is purer.^{[clarification needed]} The processes used are of many types, including pyrometallurgical and hydrometallurgical techniques.