The invention is directed to a method for the production of ammonium paratungstate tetrahydrate by thermal treatment of ammonium paratungstate decahydrate in an aqueous suspension. The ammonium paratungstate tetrahydrate can be produced with high purity and high yield. The production method may furthermore be carried out in a simple and energy-efficient manner.

 

The invention is related to a process for preparing ammonium paratungstate tetrahydrate which comprises converting ammonium paratungstate decahydrate suspended in an aqueous phase into ammonium paratungstate tetrahydrate by heating.

 

In the light of this prior art, it is an object of the present invention to provide an economical process which allows a highly pure ammonium paratungstate tetrahydrate to be prepared in a high product yield in a simple process.

 

A further object of the invention is to provide an ammonium paratungstate tetrahydrate having a very high purity.

 

Example 

100 liters of an ammonium- and tungsten-containing solution containing 3.5 g/l of NH3, 45.2 g/l of W and 50 liters of deionized water were placed in a heatable 200 liter stirred reactor. 200 kg of APT decahydrate were added while stirring. The suspension was subsequently treated at 85° C. for three hours while stirring. The NH3 concentration of the liquid phase was 3.5 g/l at an NH3:W molar ratio of 0.83:1. The pH at room temperature was 6.9. The mass ratio of solid to aqueous solution was 1.14:1. After the treatment, the suspension was filtered, the product was washed with 10 liters of deionized water and finally dried at 100° C. The amount of product was 190 kg. This corresponded to a yield of 98.1%.