The producing process of ammonium metatungstate:

A lot of preparation of AMT, the main preparation methods of the principle technique:

1.Use ammonium tungstate solution as raw material, solvent extraction and ion exchange method is first prepared by metatungstate solution, then by evaporation and crystallization get ammonium metatungstate.
2.Use sodium tungstate by solvent extraction solution as raw material in AMT solution, followed by evaporation and crystallization to obtain ammonium metatungstate.
3.The heating thermal dissociation of APT, which lost its part Ammonium And the water of crystallization, converted to ammonium metatungstate easily soluble in water, then Evaporation and crystallization Get ammonium metatungstate.
4.APT in the water is mixed with acid is neutralized to PH 3-4 condition. APT into AMT solution, followed by evaporation and crystallization to obtain ammonium metatungstate.

U.S. mostly use ammonium tungstate solution as raw material, first obtained ammonium metatungstate solution using solvent extraction or ion exchange method. Some European countries more to use sodium tungstate solution as raw material using solvent extraction. China mainly use thermal decomposition method that use ammonium paratungstate (APT) as raw material.