Energy Saving and Ultra Coarse Tungsten Powder Preparation Process

Ultra coarse tungsten powder is the main raw material for production of coarse grained cemented carbide and its downstream products are widely used in the field of mining tools, stamping die, oil drilling, hard material etc..

Due to the high melting point of tungsten, it can only be produced by powder metallurgy, that is, tungsten oxide or ammonium paratungstate (APT) can be obtained by reducing tungsten oxide. The ultra coarse tungsten powder with the average size of 150 micron can be produced by the traditional way of producing ultra coarse tungsten powder, but it has the disadvantages of high energy consumption, large hydrogen consumption and long reduction time.

In order to overcome the shortcomings of the existing ultra coarse tungsten powder preparation method, some scholars have proposed that the technical problem to solve is to provide a manufacturing process of ultra-low tungsten powder with low energy consumption, small hydrogen consumption and short reduction time. The process steps are as follows:

1.A mixed solution of sodium tungstate and ammonium tungstate is prepared in a certain proportion. The molar ratio of sodium tungstate to ammonium tungstate is 1:40.

2.The prepared solution is heated to boiling. When the volume evaporates 80% to 90%, it stops heating and sends it into the far-infrared oven. After drying at 2h for 150 degrees, the precursor of ammonium partrunate and sodium tungstate crystal mixture is obtained.

3.The precursor is sifter and the -80 powder is made, and 20% of the fine tungsten powder is added to the precursor, and it is mixed with the V mixer for 2 hours.

4.Hydrogen is reduced in a tube reduction furnace. The tube diameter of the reduction furnace is 90mm, and the length is 800mm, two sets of ultrasonic generators with a center distance of 400mm are arranged on the outer surface of the furnace tube, and three sets of pneumatic hammers with a center distance of 200mm are arranged on the outer surface of the furnace tube. The flow rate of the hydrogen cross-section passing through the reduction is 0.005L / min · cm², the frequency of the ultrasonic generator is at 25-26 kHz, the striking frequency of the pneumatic hammer is 60 times / min, and the three pneumatic hammers are not simultaneously knocked on the furnace tube of the reduction furnace at the same time, the reduction time is 30min, and the ultra rough tungsten powder is obtained. The size of the super coarse tungsten powder is 150 um, and the reduction temperature is 900℃.

5.The reduced ultra coarse tungsten powder was cleaned and cleaned by deionized water in the ultrasonic tank, filtered and dehydrated with industrial alcohol, then dried in the vacuum drying oven for 1 ~ 2H at 80 degrees. Finally, the fine tungsten powder was sieved and recycled.

Compared with the existing super coarse tungsten powder preparation process, this method not only has low energy consumption, low hydrogen consumption, short reduction time, but also the quality is stable.

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