Ammonium Paratungstate is produced by evaporation of purified ammonium tungstate solution to obtain pure paratungstate crystals. Controls of time, temperature, concentration, and pH determine the quality and physical characteristics of the ammonium paratungstate crtasls. 

SUMMARY OF THE PROCESSING

It is an object of the present invention to provide for a simple and inexpensive method for producing ammonium metatungstate from ammonium paratungstate in good yield and relatively pure form by a process capable of withstanding the rigors of commerical manufacturing. Other and further objects of the present invention will become apparent from a reading to the description of the present invention as hereinafter set forth. In accordance with the present invention, there is provided a process for preparing ammonium metatungstate from ammonium paratungstate comprising introducing ammonium paratungstate into an anode chamber of an electrolytic cell having an anode in an anode chamber and a cathode in a including an inert liquid permeable media separating the anode chamber from the cathode chamber, passing a direct electric current through said cell for transporting ammonium ions from the anode chamber through the liquid permeable media to increase concentration of ammonium metatungstate in the electrolyte within the anode chamber, and withdrawing ammonium metatungstate from the anode chamber. According to another aspect of the present invention, the liquid permeable media comprises a hard, dense material capable of withstanding the rigors of commercial manufacture and having a plurality of pores suitably sized for the passage of ammonia ion therethrough while hindering the passage of the tungstate ion.