Ammonium Metatungstate Preparation--Thermal Degradation Method (1)
- Details
- Category: Tungsten Information
- Published on Wednesday, 26 July 2017 10:45
Ammonium Metatungstate (AMT) is an important compound product in tungsten smelting process.
It is widely used. The common methods of preparing ammonium metatungstate include thermal degradation and ion exchange, extraction, electrodialysis and neutralization.
The method of thermal degradation is the preparation process of ammonium metatungstate with ammonium paratungstate (APT) as raw material. This method is also the main process for preparing ammonium metatungstate (AMT) at present.
The calcination temperature of ammonium paratungstate and the depressurization of ammonia and water vapor were controlled by thermal degradation, ammonium metatungstate solution was prepared by hydration. Ammonium metatungstate solids can be obtained by concentrating and cooling crystallization of the solution. The heat reaction formula is as follows:
( NH4 )10[H2W12O42]·4H2O ==( NH4 )6[H2W12O40]·xH2O+4NH3+nH2O
( The x value is 2-4, and under industrial conditions, x is generally 3 or 4, n=4-x )
The key point of thermal degradation method is the control of thermal degradation temperature. Too high temperature wil generate anhydrous wolframic acid. Too low temperature will result in the removal of ammonia and water from ammonium paratungstate insufficient. The appropriate temperature is the key to increase the conversion rate of ammonium paratungstate (APT). Industrial production shows that the suitable temperature range of ammonium metatungstate (AMT) prepared by ammonium paratungstate (APT) thermal degradation method is between 210 °C and 265 °C.
The industrial application of thermal degradation also provides a good shelter for substandard ammonium paratungstate (APT). As we all know, the extraction of ammonium paratungstate (APT) is a systematic project. A small error in production can cause a large deviation in the physical and chemical properties of APT and become a nonconforming product. What should we do with the waste of APT? That's OK. Thermal degradation method can help. With the help of thermal degradation method, the waste of APT can turn into useful AMT.
Read more: http://news.chinatungsten.com/en/tungsten-information/97171-ti-12444
[ Ammonium Metatungstate Preparation -- Thermal Degradation Method (2) ]
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