Optimized Process of Tungsten Oxide Production by Pyrolysis

Tungsten oxide (WO₃), a yellow-green powder, is an important oxide of tungsten. At present, it is mainly used to manufacture W powder and WC powder, i.e. tungsten rod, tungsten wire and cemented carbide, which are the main terminal objects of tungsten oxide (WO₃).

In order to improve the fineness of tungsten oxide (WO₃) produced by pyrolysis, and obtain an economical and effective production method and corresponding products which can meet the requirements of both particle size and output, a smelter in Jiangxi Province adopted the following scheme to pyrolyze tungsten oxide.

First, ammonium paratungstate (APT) with a purity of more than 99.9wt% and a particle size of about 5um was selected as the raw material. Distilled water was added into the reaction vessel and stirred with an electromagnetic stirrer. The stirring speed was 180-200r/min. Citric acid solution was added while stirring.

Secondly, high purity ammonium paratungstate (APT) was added to the reaction vessel while stirring, and the final molar ratio of ammonium paratungstate (APT) to citric acid was calculated to be 3.

Thirdly, after adding high purity ammonium paratungstate (APT), 30% ammonia water was added and the reaction solution was evenly stirred.

Fourthly, the reaction solution is concentrated in an evaporation container, and the concentrated solution is dried in a drying equipment at 150-160 ℃ to obtain the precursor.

Fifthly, the precursor was crushed in the grinding equipment, and then heat-treated in a crucible with 60 ml/min oxygen flowrate calculated by G precursor at 510 ℃. Finally, tungsten oxide (WO₃) nano-powder was obtained.

The key points of the scheme are the selection of ammonium paratungstate (APT) and citric acid, the appropriate ratio of APT and citric acid, and the preparation parameters, mainly the flow rate of oxygen and the heat treatment temperature, to obtain tungsten oxide (WO₃) nano-powder with uniform particle size distribution.

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