Preparation of Ultrapure Tungsten Powder with Blue Tungsten Oxide

Blue tungsten oxide is the main tungsten oxide product at present. It is the main raw material for making ultra pure and ultra-fine tungsten powder. It uses blue tungsten oxide to restore ultra pure tungsten powder, and its process includes four processes: calcination, reduction, acid washing and anti oxidation.

1. Calcining
The ammonium paratungstate (APT) raw material into the rotary furnace, at a temperature of 550 at a temperature of 750 ℃, without ammonia, but the use of ammonium paratungstate (APT) decomposed from ammonia to maintain reduction furnace atmosphere, APT in the high temperature decomposition of tungsten trioxide, tungsten trioxide by NH3 solution generated by the weak hydrogen reduction blue tungsten oxide. For from the furnace tube out of the head of the 100Kg (50kg-150kg) blue tungsten oxide and the end of production from the last 100Kg in the furnace tube flow (50kg-150kg) blue tungsten oxide with more impurities, reducing the production of ultra pure tungsten powder before removal from raw materials and blue tungsten oxide; tungsten oxide after drop tube furnace wall sticking to get rid of the impurity content is high.

2. Restore
The roasted sifted blue tungsten oxide into a polished stainless steel boat in the reduction furnace after 800-950 ℃ high temperature, the hydrogen dew point is less than -60 ℃, the oxygen content of less than 5ppm hydrogen atmosphere , reduced to the average particle size of Fei 3.0-6.0 um metal tungsten powder, then, the ultrasonic sealed vibrating screen (dispersing effect is good) will be used to remove the impurities from the tungsten powder two times through the 200 mesh stainless steel screen, and then the screened tungsten powder will be put into the inert gas to protect it.

3. Pickling
The purpose of pickling is to remove impurities in tungsten powder. First with 1% -5% of an inorganic acid washing tungsten powder 20-40 minutes, and then 1% -5% of another inorganic acid washing tungsten powder 20-40 minutes. Using pure tungsten powder will be attached to the surface of the acid washing to neutral pH = 5 7, finally in a vacuum atmosphere, tungsten powder drying at a temperature of 80-95 ℃.

4.Anti oxidation
After pickling and sifting, the tungsten powder is mixed in the mixer and packed into the packaging bag, then the packing bag is evacuated into a vacuum, and then filled with inert gas and sealed. The ultra pure tungsten powder is isolated from the air in the process of preservation, so as to prevent oxidation.

The above is a common blue tungsten oxide reduction of high pure tungsten powder, tungsten products so the purity is not less than 99.99%, with an average particle size of 3.0-6.0μm, an oxygen content of ≤300ppm, and an oxygen content of ≤300ppm, the process is relatively simple. The final price of high-purity tungsten is about twice as expensive as ordinary tungsten powder, and there is room for further improvements.

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