Refining
The method of extraction of pure metal from impure or raw metal proper conditions is called refining of the metal. Several methods are used to obtain metals of high purity. These are as follows.
Distillation-
Zn, Cd, Hg metals are treated by this method because they are low boiling point metals.
Electrolytic Refining-
Copper, silver, gold, aluminum and lead metal are treated by this method, anode of impure metal, and cathode of metal are made.
Zone Refining-
This method is based in the principle that the solubility of impurities is higher in the molten state than in the solid state of the metal. This metal is useful in obtaining very high purity semiconductors and other highly pure metals such as germanium, silic, boron, gallium and indium.
Vapour Phase Refining-
In this method, the metal is converted in to a voltatile compound. Thereafter, it is decomposed to obtain pure metal. Example Mode process It used for nickel.
Von-Arkell Method-
It is used for zirconium and titanium.
Chromatographic Method-
This method is based on the principle that absorption of different components of a mixture is different at the absorbent. Purification of elements found in small quantities is done in this method.
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