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Ammonium
Metatungstate Picture
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The thermal
decomposition method of ammonium paratungstate to prepare ammonium metatungstate: ammonium
paratungstate and a small amount of citric acid catalyst after mixing into the
far infrared, rotary furnace, controlled thermal decomposition temperature 200 ～ 280 ℃, decomposition of about 1 h. The removal of
ammonia and water, ammonium paratungstate weightlessness rate was 5% ~ 6%.
The thermal decomposition products immediately after the slurry, adding proper amount of ammonia, Ph value is adjusted in the 3 to 4 range, at 90 ℃ digestion slurry. After evaporation to ammonium metatungstate content of 50% can be used as a liquid product to sell, crystallization, when the evaporation to the original volume of 20% filtering and separating, granulating product. Also can be evaporated and concentrated liquid product is prepared by spray drying. As of 45% ~ 50% ammonium metatungstate by high-speed centrifugal rotary spray dryer, imports of hot air temperature 250～300 ℃, outlet temperature 90 ～ 95 ℃, the obtained product is a spherical crystal, particle size is 200 mesh accounted for 95%, free water <1.5%.
The thermal decomposition products immediately after the slurry, adding proper amount of ammonia, Ph value is adjusted in the 3 to 4 range, at 90 ℃ digestion slurry. After evaporation to ammonium metatungstate content of 50% can be used as a liquid product to sell, crystallization, when the evaporation to the original volume of 20% filtering and separating, granulating product. Also can be evaporated and concentrated liquid product is prepared by spray drying. As of 45% ~ 50% ammonium metatungstate by high-speed centrifugal rotary spray dryer, imports of hot air temperature 250～300 ℃, outlet temperature 90 ～ 95 ℃, the obtained product is a spherical crystal, particle size is 200 mesh accounted for 95%, free water <1.5%.
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