APPLICATIONS FOR TELLURIUM

Tellurium became widely used after World War II. It had modest usage in some non-ferrous alloys and was a secondary vulcanizing agent in the natural rubber industry. In 1958 interest developed in the thermoelectric properties of bismuth telluride and lead telluride materials; solid state cooling devices found their way into satellites, but consumer products were not developed at that time. In the 1970's tellurium was added to selenium photoreceptor materials to broaden the spectral range of copiers. Mercury-cadmium-telluride compounds found applications in infrared detector systems in military and space systems. Currently, metallurgical and chemical usage dominates tellurium demand, estimated at 220 metric tons per annum.

• Metallurgy: 75% of demand. Elemental Te added as an alloying element (0.04%) to free machining steels is the largest single use. Added to copper, Te improves machinability without materially decreasing conductivity. Added to lead, Te improves resistance to vibration and fatigue. As an additive to cast iron, Te helps control the depth of chill; in malleable iron Te is a carbide stabilizer.
   
• Chemicals: 15% of demand. As a secondary vulcanizing agent for rubber, an accelerator in processing rubber to retain flexibility at elevated temperatures. A component of catalysts for synthetic fiber intermediates and for chemicals manufacturing.
   
• Electrical: 8% of demand. As an alloy component in selenium photoreceptors for copiers and printers. As the cadmium-mercury-telluride compound, the major photosensitive material employed in infrared detector systems. As an alloy component in bismuth telluride cooling devices..
   

  Other Applications: 2% of demand. As an ingredient in blasting caps, as a pigment to produce various colors in glass and ceramics, etc.