Method and Apparatus for Preparing Blue Tungsten Oxide by Ammonium Paratungstate Self-reduction

Blue tungsten oxide can be used to produce tungsten powder. The melting point of tungsten is up to about 3410 ℃, it is of high hardness, ductility is strong, at room temperature without air erosion, because tungsten has these characteristics, which make tungsten  powder  widely used in many fields, such as preparing high proportion alloy, automatic watches pendulum, telecommunications vibrator, balance board aircraft, anti-χ rays, α-rays, γ-ray protection plates and the like.

At present, domestic production of blue tungsten oxide is based on using ammonium paratungstate as raw material in the port of ammonia gas or liquid ammonia fed by the decomposition of nitrogen, hydrogen or mixed gas directly into hydrogen, in a feed port of the suction fan, ammonia or nitrogen, hydrogen gas or hydrogen gas feed port access from the out, after a tube, is discharged from the feed port, when the discharge port access is ammonia, the ammonia gas in the furnace tube will be the role of tungsten oxide is decomposed into nitrogen and hydrogen, the hydrogen which will be reduced to tungsten trioxide, can be obtained at the discharge port of blue tungsten oxide; when the discharge port pass into the mixed gas by the decomposition of ammonia nitrogen and hydrogen formed, then where will the hydrogen reduction of tungsten trioxide blue tungsten oxide, can be obtained at the discharge port of blue tungsten oxide; when the discharge port is passed directly into the hydrogen, the hydrogen gas into the tungsten trioxide will be reduced to blue tungsten oxide.

As a result of the above-described method for preparing the required blue tungsten oxide, which leads to the need to increase the consumption of ammonia, resulting in increased processing costs; and by the decomposition of ammonium paratungstate Most ammonia with drawn from the inlet at the fan discharge to the atmosphere, the atmosphere is contaminated, thereby affecting the health of the people.

A method of preparing ammonium paratungstate from reducing preparation blue tungsten oxide, which is based on ammonium paratungstate 5 (NH4) 2O · 12WO3 · 5H2O as raw material, characterized in that: it comprises the following steps:.
a: Ammonium paratungstate gets heated and is decomposed into tungsten trioxide WO3, ammonia NH3 and water vapor H2O; under the heating temperature 400 ℃ ~ 600 ℃;.
b: From tungsten oxide catalyst to ammonia NH3 decomposition, the thermal decomposition of the ammonia NH3 then is further decomposed into nitrogen N2 and hydrogen H2;.
c: By controlling the reaction temperature and proper furnace gas pressure, the reduction of tungsten trioxide WO3 and tungsten blue oxide WO2.9 is made under temperature 550 ℃ ~ 800 ℃; furnace gas  pressure is 0-2 mbar.

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