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How to Prepare Tungsten Powders by Ammonium Paratungstate?

Details: Category: Tungsten Information; Published on Wednesday, 11 February 2015 11:23; Written by zsq; Hits: 512

Coarse and spherical tungsten powders were prepared by wet hydrogen reduction.Ammonium tungstate solutions with the additives of Li,Na and K alkali metal salts were used as raw materials.The effects of the type and content of the alkali metal salts as well as reduction time on the microstructure,chemical composition,phase composition, and particle size of ammonium paratungstate(APT) and coarse tungsten powders were investigated by scanning electronic microscopy,energy dispersive spectroscopy,X-ray diffraction,and test sieves.It is shown that ideal tungsten powders with good fluidity,sphericity,integrity and even distribution can be obtained by using the ammonium tungstate solution with 3 g·L~(-1) NaCl,KCl and Li_2CO_3 and reducing at 1000℃for 180 min in wet hydrogen atmosphere.The average particle size of the obtained tungsten powders is 67μm,the maximum particle size is 150μm,the biggest loose density is 13.41 g·cm~(-3),and the best powder flowability is 9 s for 50 g tungsten powders.

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How to Reducing the Average Particle Size of Ammonium Paratungstate Powders?

Details: Category: Tungsten Information; Published on Wednesday, 11 February 2015 11:11; Written by zsq; Hits: 525

A process for reducing the average particle size of an ammonium paratungstate powder having the steps of heating the ammonium paratungstate powder at a temperature of between about 110° C. to about 205° C. For a time sufficient to reduce the average particle size of the ammonium paratungstate powder by at least 20 percent. The average particle size of the obtained tungsten powders is 67μm,the maximum particle size is 150μm,the biggest loose density is 13.41 g·cm~(-3),and the best powder flowability is 9 s for 50 g tungsten powders.

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Removing of Stannum in Producting Ammonium Paratungstate

Details: Category: Tungsten Information; Published on Wednesday, 11 February 2015 10:50; Written by zsq; Hits: 512

Since 1970s,Chinese tungsten metallurgy has made remarkable progress and product quality ranked high because of application of ion-exchange technology.Ammonium paratungstate quality is (affected) by stannum in solution. In recent years, some new methods about removing of stannum from tungsten are put forward. According to this status, developing trend of W-Sn separation technology in our country is analyzed.

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Characterization of WO3 from Ammonium Paratungstate Via Hydrothermal Method

Details: Category: Tungsten Information; Published on Wednesday, 11 February 2015 10:52; Written by zsq; Hits: 451

Tungsten trioxide powder has been prepared from ammonium paratungstate via hydrothermal method using orthogonal and mono-level design of experiments. The effects of preparation process on particle size, specific surface area, crystal form and crystalline morphology of the tungsten trioxide was investigated by TEM and XRD etc. It was found that the optimum conditions of the preparation are hydrothermal crystallization for 8 h at 180°C, followed by vacuum drying at 45°C and calcination at 500°C for 2 h. The blank reference experiment shows that hydrothermal crystallization treatment favors the formation of hexagonal tungsten trioxide, and the tungsten trioxide powder sample prepared by this method has a high degree of crystallinity.

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Comparing Thermal and Mechanochemical Decomposition of Ammonium Paratungstate (APT)

Details: Category: Tungsten Information; Published on Wednesday, 11 February 2015 10:45; Written by zsq; Hits: 475

In this research, the possibility of mechanochemical decomposition of ammonium paratungstate (APT) has been studied, and compared with thermal decomposition method. For this purpose, APT powders were milled using a planetary ball mill up to 36 h and under air atmosphere. For thermal decomposition, APT powders were heated for 30 minutes at 300 and 450 °C in air atmosphere. X-ray diffraction (XRD), differential scanning calorimeter (DSC), and thermo gravimetric analyzer (TGA) were used to