Preparation of Violet Tungsten Oxide with High Fluidity

Violet tungsten oxide is an important raw material for the preparation of tungsten powder. During the preparation process, the fluidity of violet tungsten oxide directly determines the feeding speed of rotary furnace. Only when violet tungsten oxide with high fluidity is applied, can high-quality tungsten powder be prepared.

Tungsten is not only a kind of refractory non-ferrous metal, but an important strategic resource. It is widely used for its high melting point, high hardness and strong ductility. Rotary reduction furnace has become the main equipment of tungsten powder production. During the feeding process, violet tungsten oxide is placed on the feeding inlet, then flows into the furnace tube by its own gravity. Though this kind of feeding mode saves the labor, it asks for the strict requirement of the fluidity of raw material – violet tungsten oxide. Specifically, the use of violet tungsten oxide with poor fluidity will leads to a large fluctuation of feed quantity and affect the quality of tungsten powder product as well.

Here is a preparation method of violet tungsten oxide with high fluidity as following as:

1.The ammonium tungsten compound is used as raw material to be calcined in a closed calciner. The furnace temperature is controlled by gradient method. There are 2-6 calcining zones. The temperature at the feed end is 700-800°C and the temperature at the discharge end is 500-700°C.

2.The vacuum degree in the furnace is (0.1-1.5) x10⁴ Pa. And the whole calcination is carried out in non-oxidizing atmosphere.

3. The feed speed of raw materials is 50-250 kg/ h.

4.The calcination time is 20-50 minutes.

5.The furnace charge is cooled by the cooling water jacket mounted in the calciner. Then it is discharged and sifted to obtain violet tungsten oxide product with a fluidity less than or equal to 30 seconds or 50 seconds.

The preparation of violet tungsten oxide with high fluidity not only improves the automation of the production of violet tungsten oxide, but reduces the production cost effectively.

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