What is Tungsten?
30 Oct 2014
Tungsten, also known as wolfram is a chemical element with the symbol W and atomic number 74. Tungsten is a lustrous, silvery white metal with the highest melting point of all metals at 3,422°C. Pure tungsten is ductile, however small concentrations of carbon and oxygen give impure tungsten its hardness and brittleness.
What is Tungsten used for?
Tungsten is predominantly used as carbide in cemented carbides. Cemented carbides, also called hardmetals, are wear-resistant materials used in metalworking, mining and construction industries. Other uses include metal wires, electrodes, electronic, electrical, heating and welding applications.
Where is Tungsten found?
Native tungsten has never been found and therefore tungsten bearing minerals must be reduced to metallic conditions by artificial means. There are more than thirty tungsten bearing minerals known, however only two of them are important for industrial use, namely wolframite and sheelite. Wolframite is a black to greyish brown ore with a submetallic to resinous lustre and is a general term for iron and manganese tungstates where the iron/manganese ratio can vary. A mineral with more than 80% FeWO4 is called ferberite and a mineral with more than 80% MnWO4 is called hübnerite.
Scheelite is a calcium tungstate (CaWO4) forming translucent crystals ranging in colour from white, yellow, orange, greenish grey to brown. Scheelite is fluorescent bright blue-white under ultraviolet light.
Tungsten deposits are typically associated with magmatic or hydrothermal processes within or near orogenic belts. Tungsten is found in all continents with approximately 70% of the world’s known deposits located in a belt that stretches through southern China and into Burma. China is the world’s largest producer of tungsten followed by Russia, Canada and Bolivia.
How is the tungsten price measured?
The tungsten price is generally quoted in US dollars per metric tonne unit (MTU) of tungsten trioxide (WO3). The price depends on the grade and the impurities in the concentrate. Pure wolframite concentrate contains approximately 79.3% tungsten metal and is sold at a premium. Lower grade concentrate products acceptable for sale range from 62% WO3 and 72% WO3. The tungsten price is also quoted in US$ per MTU in Ammonium Paratungstate which is a secondary product made from wolframite or scheelite concentrates.
International Tungsten Industry Association, www.itia.info
US Geological Survey, www.usgs.gov
Metal Bulletin, www.metalbulletin.com
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