High Purity Ammonium Tungstate Spray Drying Process

Recently, researchers have created a method for the preparation of high purity ammonium tungstate, which can be used to obtain 5N high purity ammonium tungstate products and can be used in large-scale industrial production. The steps of this process are:

(1) The tungstate solution is dissolved in water, and the solution of tungstate salt solution is purified by filtration membrane.

(2) The ammonium tungstate water solution is obtained by the ion exchange of ammonium tungstate exchange resin after the purification of the purified tungstate solution. (3) The ammonium tungstate solution is dried and the ammonium tungstate product is obtained.

The filter membrane purification preferably uses a double filter membrane purification device. The first layer of microfiltration membrane can intercept the solid suspended particles with larger impurity particles, and the second layer of nanofiltration membrane can intercept large molecular weight ion and multivalent ionic group, such as the tungsten acid root ion, and let the material with smaller molecular weight pass through.

The spray drying process uses the atomizer to disperse the material into fine droplets, and rapidly evaporates solvent in the hot drying medium to form a dry powder product, preventing the products from being contaminated by foreign metal impurities during the production process. The general spray drying includes four stages: (1) The atomization of the liquid and the mixture of the mist group and the hot drying medium; (3) The evaporation and drying of the droplets; (4) The separation of dry products from the drying medium. The purity, grain size, particle size distribution and particle morphology of ammonium tungstate products obtained by spray drying are improved compared with the traditional cryo crystallization and evaporation crystallization process.

The preparation method of high purity ammonium tungstate is simple, with little loss of tungsten and can obtain 5N grade high purity ammonium tungstate product and is suitable for large-scale industrial production.

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