This page deals with the extraction of tungsten from tungsten(VI) oxide, WO3, produced from tungsten ores such as wolframite or scheelite.
The production of the tungsten(VI) oxide from the ores is complicated, and not needed for any UK A level (or equivalent) syllabus. All we are interested in is the final reduction of the oxide to the metal.
Pure tungsten can't be obtained by reducing tungsten(VI) oxide using carbon, because it reacts with carbon to make tungsten carbide. Instead, the reducing agent is hydrogen.
The extraction process
Powdered tungsten(VI) oxide is heated to temperatures in the range 550 - 850°C in a stream of hydrogen.
An excess of hydrogen is used, and this carries away the steam produced during the reaction. The hydrogen is dried and recycled.
Great care obviously has to be taken to keep the whole system free of air to avoid explosion risks with the hydrogen at these high temperatures.
© Jim Clark 2009