Selenium and Selenium Compounds

Abstract Selenium, the 30th most abundant element, lies between sulfur and tellurium in Group 16(IVA) of the Periodic Table. There are no ores mined for selenium value. Rather, selenium is recovered throughout the world as a by‐product in the refining of sulfide‐bearing copper minerals. These processes are discussed.The chemical and physical properties of selenium are often similar to those of sulfur, but are sufficiently different to account for specialized applications. Both organic and inorganic compounds are known. Commercial elemental selenium along with the stable metallic selenides are considered relatively nontoxic. Selenium plays a role in living organisms and small doses are used in medicine and as a diet supplement. Selenium deficiency occurs is some parts of the world and diseases relating to this deficiency have been studied. Selenium's main use is as a decolorizing agent in glass and ceramics. Metallurgical applications involve its use as a minor alloying additive. Other uses include electrical and optical applications, in agriculture as an essential micronutrient, in organic chemistry, medicine and nutrition, pigments, rubber, and lubricants.