The Main Methods for The Production of Tungsten Powder

Tungsten powder is the main raw material for the production of tungsten carbide, pure tungsten, tungsten alloys and other tungsten products, with over 70% of tungsten powder being used in the production of tungsten carbide. Currently, the main methods for obtaining tungsten powder are:

Hydrogen reduction method of tungsten oxide

This is a method of reducing tungsten oxide to tungsten powder using H2 as the reducing agent. Taking the hydrogen reduction of WO₃ as an example, the overall reaction is:

WO₃+3H₂=W+3H₂O

Currently, the tungsten oxides used as raw materials for hydrogen reduction mainly include yellow tungsten trioxide (WO₃), blue tungsten oxide (mainly WO₂.₉), and purple tungsten oxide (WO₂.₇₂), etc. The hydrogen reduction method of tungsten oxide is the main method for producing tungsten metal powder at present.

2. Hydrogen reduction of tungsten halides

This is a method that uses H2 as a reducing agent to reduce tungsten halides (such as tungsten chloride, tungsten fluoride) to metallic tungsten. For example, in the case of hydrogen reduction of WCl6, the overall reaction is:

WCl6+3H₂=W+6HCI

The hydrogen reduction process of tungsten halides is a gas-phase reaction, mainly used in chemical vapor deposition to produce ultrafine tungsten powder or tungsten coatings. Currently, the chlorination reduction method of tungsten halides is only used for small-scale production.

3. Carbon Reduction Method of Tungsten Oxides

When a mixture of tungsten oxides and carbon is heated to a certain temperature, the tungsten oxides are reduced to tungsten powder. Taking the carbon reduction of WO₃ as an example, the overall reaction is:

WO₃+3C=W+3CO

WO₃+3CO=W+3CO₂

Sometimes, a small amount of hydrogen is introduced into the furnace to promote the carbon reduction process. However, the tungsten powder produced by this method has a relatively high carbon content and is not suitable for tungsten products. Currently, the carbon reduction method for preparing tungsten powder is less used, but it is increasingly applied in the direct production of tungsten carbide, especially ultrafine tungsten carbide powder and tungsten carbide composite powder.

4. Other Methods

Other methods for producing metallic tungsten include molten salt electrolysis, zinc reduction, and plasma hydrogen reduction, among others.