About 61,300 tonnes of tungsten concentrates were produced in the year 2009. Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO3), which is heated with hydrogen or carbon to produce powdered tungsten. Because of tungsten's high melting point, it is not commercially feasible to cast tungsten ingots. Instead, powdered tungsten is mixed with small amounts of powdered nickel or other metals, and sintered. During the sintering process, the nickel diffuses into the tungsten, producing an alloy.
Tungsten can also be extracted by hydrogen reduction of WF6:
- WF6 + 3 H2 → W + 6 HF
or pyrolytic decomposition:
- WF6 → W + 3 F2 (ΔHr = +)
Tungsten is not traded as a futures contract and cannot be tracked on exchanges like the London Metal Exchange. The prices are usually quoted for tungsten concentrate or WO3. If converted to the metal equivalent, they were about 19,000 per tonne in 2009.
Read more about this topic: Tungsten
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