Tellurium series

详情

　Tellurium is a semi metallic, lustrous, crystalline, brittle, silver-white element. It is usually available as a dark grey powder; it has the properties both of the metals and the non metals. Tellurium forms many compounds corresponding to those of sulfur and selenium. When burned in air tellurium has a greenish-blue flame and forms tellurium dioxide as a result. Tellurium is unaffected by water or hydrochloric acid, but dissolves in nitric acid.

　　Tellurium is present in coal at up to 2 ppm. This is probably the major source of this metal, which can be taken by plants from soil. Tellurium in plants can reach level as high as 6 ppm, although few food plants have more than 0.5 ppm and most have less than 0.*5 ppm. Samples of uncombined tellurium can be sometimes found, but they are extremely rare. There are some tellurium minerals (calaverite, sylvanite, tellurite), but none is mined as a source of the element. World production is around **0 tons/year. Major producers are USA, Canada, Peru and Japan. The reserves of this element have not been assessed.

　　Tellurium is often used as an additive to steel and it is often alloyed to aluminum, copper, lead or tin. Tellurium is added to lead to improve its durability, strength and resistance to corrosion. It can be used for cast iron, ceramics, blasting caps, solar panels, chalcogenide glasses. When added to rubber, tellurium speeds up the curing process and makes the product less susceptible to ageing and less likely to be affected by oil, which softens normal rubber.