A Preparation Method of High-purity Ammonium Paratungstate

The researchers proposed a preparation method of high-purity ammonium paratungstate. This process optimizes the original high-purity APT production process and reduces production costs.

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A Preparation Method of High-purity Ammonium Paratungstate

Step One: Calcine APT to produce WO3. Put APT into feed bin and send it into rotary furnace through screw feeder at a constant speed. Control calcination temperature and atmosphere in rotary furnace. The feed volume is 160 kg/h. The calcination temperature is 560 °C in the first zone, 650 °C in the second zone, and 690 °C in the third zone, respectively. After calcining, conversion rate of APT to WO3 reached 99.05%.

Step Two: Control the temperature of 70 g/L ammonia solution at 100 °C, and liquid-solid ratio at 4:1 ml/g. WO3 is added into the solution while stirring, and reacted for 2 h to obtain an ammonium tungstate solution, and then filtered.

Step Three: After filtering, measure the ammonium tungstate solution into an evaporative crystallization pot for evaporative crystallization, control evaporative crystallization steam at 1-4 kgf/cm2, when specific gravity of the solution is close to 1.06 g/cm3, stop heating, and separate crystal and mother liquor to obtain aqueous ammonium paratungstate.

Step Four: Remove excess water in aqueous ammonium paratungstate by steam drying to obtain high-purity ammonium paratungstate.

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