Ammonium metatungstate is a white crystalline salt with the chemical formula of AMT. It is described as the most important raw material for all other tungsten products, so its preparation is of great significance. At present, there are many preparation methods of ammonium metatungstate. And it can be divided into two main preparation methods, i.e., solid phase conversion method and liquid phase conversion method.
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Ammonium Metatungstate Preparation
A solid phase conversion method, such as using ammonium paratungstate (APT) as a raw material, heating to crack APT, causing it to lose part of ammonia and crystal water, and converting it into water-soluble ammonium metatungstate (AMT). After filtering to remove insoluble impurities, AMT can be obtained by evaporation and crystallization or spray drying. A liquid phase conversion method, such as ion exchange method, neutralization method and nanofiltration method. And it is mainly to convert APT solution to AMT solution by adjusting the pH of the raw material solution using APT or sodium tungstate as the raw material, filtering to remove insoluble impurities and then crystallized or spray dried to produce AMT.
