Direct Reduction of Ammonium Metatungstate and Ammonium Paratungstate Producing Tungsten Powder 2/2

Specific steps are as follows:
The raw materials used in this method are ammonium metatungstate (AMT) and ammonium paratungstate (APT), which are reach or above pure grade in industrial.
Scheme one: A certain proportion of AMT and APT mixed, and then reducing
1. Raw materials APT and AMT in accordance with 20~80% accounted for AMT, and the rest of the proportion of APT mixed;
2. Placed the mixed raw material powder in hydrogen reduction furnace for One-Step reduction, temperature controlled in 750~1000°C, keep the highest temperature for 0.5 ~ 5h;
3. Screening and drying tungsten powder in vacuum, then get the tungsten powder with high strength.

Scheme two: Reducing APT and AMT respectively, and then mixed tungsten powder in a certain proportion
1. Place the two kinds of material powder respectively in different reduction furnace for one-Step reduction, control temperature in 700~1000°C, keep the highest temperature for 0.5 ~ 5h;
2. Screening and drying tungsten powder in vacuum respectively;
3. Mixing the two kinds tungsten powder dried in different proportion, then get tungsten powder with high strength.

The advantages of this method are reflected in the following 3 aspects:
1. There is no need to go through calcination and intermediate process, because we use AMT and APT for direct reduction, low energy consumption and simple process;
2. Purity of tungsten powder prepared is very high (higher than 99.0%), with good property of suppression, strength of compression fracture reached 2.8~4.0Mpa, meeting the requirements of tungsten powder with high strength in industrial;
3. Particle size of tungsten powder prepared is uniform, high sintering activity, which is conducive to the preparation of high properties tungsten products.

Therefore, control the morphology and size of APT can improve the formability and compressive strength of tungsten powder. Control from the source, help to reduce the cost for subsequent links and make up the basic trend of the final products to produce tungsten powder with stable quality.

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