ART Ultrafine Tungsten Powder Made by Self Reduction Tungstate

In the production of tungsten powder, tungstate thermal decomposition is mostly used to produce blue tungsten oxide, blue tungsten oxide hydrogen reduction process to tungsten powder. The conventional process generally uses ammonium paratungstate as the initial raw material, but it is difficult to obtain ultrafine tungsten powder with average particle size of less than 1μm by hydrogen reduction.

Ultrafine tungsten powder can be prepared by hydrogen reduction by ART. Although the results of the preparation of ART in the laboratory are satisfactory, when this preparation method is applied to the industrial production experiment, the precipitation rate is not high, the ART product is difficult to filter dry, and the consumption of hydrazine in the raw material is large.

Recently, some scholars have made a breakthrough in ART, including 1. ammonium tungstate solution storage tank. 2. Evaporator. 3. Hydrous amine storage tank. 4. Reactor.5. Solid-liquid separation equipment. 6. Dryer. 7. Tail liquid storage tank. 8. Row or rotary kiln. 9. Tube furnace or rotary kiln. 10. Ultra-fine tungsten powder products.

Ammonium tungstate solution in the ammonium tungstate solution storage tank [1] contains a tungsten acid root ion 0.5-1.5mol/l, which also contains a certain amount of free ammonia or ammonium chloride (or ammonium nitrate), adding ammonia to the evaporator [2] to reduce the pH value to 7-9 [4]. At this time, the hydrous amine in the tank [3] is also added. In the reactor [4], the N₂H₄/WO₂ mole ratio is 0.8-1.5/l, the reaction is 4-5 hours at the temperature above 40°C. After the solid-liquid separation equipment [5], the solid is a parotungstate filter cake, and the dryer [6] is dried about 4 hours at about 110°C, the white powder ART is obtained. The obtained ART powder is sent to the industrial tube furnace or the rotary kiln [8]. Heat decomposition at 420-470°C for 20-30 minutes, pure component blue tungsten was obtained. Hydrogen or nitrogen or other inert gases can be used in the thermal decomposition of the protective atmosphere, the ultrafine tungsten powder [10] can be obtained by hydrogen reduction of the WO_2.90 pure component blue tungsten in a pipe furnace or rotary kiln [9]. The reduction temperature is 600-800°C, the reduction time is 4-6 hours, the loading amount is 150-200 grams per boat, the fine tungsten powder with different size specifications can be obtained, solid powder can be obtained. The tail liquid from the liquid separation equipment [5] comes into the storage tank [7], which can be recovered or discharged.

Compared with the existing process of producing ultrafine tungsten powder by APT, this process has the characteristics of low energy consumption and fine grain size of tungsten powder. The raw material of this process is convenient to prepare ART, and the equipment is simple. The ultrafine tungsten powder can be produced by the ART process without modification of the production equipment of the APT process. It has a good application prospect.

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