Ammonium Metatungstate Prepared from Ammonium Paratungstate

Ammonium metatungstate is an important tungsten compound, mainly used in petroleum cracking, organic synthesis, nitration and other industries as a catalyst. The dosage of ammonium metatungstate is increased with the rapid development of oil refining. The traditional way crystallization to prepare ammonium metatungstate from ammonium paratungstate has high investment, energy consumption and unstable quality of the resulting product, poor solubility, can not meet the need of catalyst.

Ammonium paratungstate used as raw material to leaching out the solution, then dilute ammonium metatungstate solution turns into a concentrated solution, and spray and drying the concentrated ammonium metatungstate solution to prepare ammonium metatungstate crystal.

Specific steps are as follows:
1. Leaching out the wet ammonium paratungstate: to wet ammonium paratungstate content 5 ~ 10% water as raw material and mix with nitric acid (HN0₃) to prepare dilute ammonium metatungstate solution;
2. The dilute ammonium metatungstate prepared by the step 1 goes through many times of static and precipitation, filtration and heat to concentration and then obtain the concentrated ammonium metatungstate solution;
3. Spray and dry, make the material dried quickly into ammonium metatungstate powder.
Its advantages lie in:
1. There is no need to roasting, so the rotary furnace equipment is useless, therefore to reduce investment of fixed;
2. The actual recovery rate of ammonium metatungstate increased;
3. Slowly and continuously feeding overcomes the problem of low solubility of ammonium metatungstate, to get ammonium metatungstate solution with high content of tungsten trioxide;
4. Use wet ammonium paratungstate product as raw material saves the process of drying and packing, to achieve the purpose of saving energy and reducing cost.

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