Symbol:Se
Melting point:221'C
Electron configuration:[Ar]3d104s24p4
Atomic number:34
Atomic mass:78.960.03u
OreCommon NameFormula
ClausthaliteClausthalitePbSe
BerzellaniteBerzelianiteCu2Se
TiemanniteTiemanniteHgSe
NaumanniteNaumanniteAg2Se

Selenium

Selenium occurs along with sulphur and pyrite ores. Selenium is used in a number of applications. It is mostly used in photocopiers and photoreceptors. It is also used in electronics equipments. It is used in chemicals and pigments. High purity of selenium dominates the copy making sector. Selenium-Tellurium alloys are used in x-ray imaging equipments. It is also used as alloying element in steel and lead. The major producers of this metal are Japan, Canada, USA, Yugoslavia and Russia.

The selenium ore is concentrated and treated with sulphuric acid in an acid chamber. The acid is electrolysed to get selenium. Then the selenium may be refined to get high purity metal of selenium. The anode mud obtained in electro refining of copper also contains selenium. The mud may be electrolyzed with sulphuric acid to recover selenium present in it. Selenium is used as alloying element in small quantity [0.3%maximum]. It is added to the stain less steel to replace sulphur. Selenium is chemically very similar to sulphur. It forms selenide globules to act as chip breakers in the austenitic stainless steels. Tellurium is added to supper alloys up to 0.5% to provide free cutting properties to copper