The main production methods of ammonium metatungstate can be summarized as follows:
- Ammonium metatungstate smelting production method-solvent extraction method
Principle of ammonium metatungstate solvent extraction method
Use organic extractants such as di (2-ethylhexyl) phosphate (D₂EHPA) or tributyl phosphate (TBP) and kerosene solvent to form an organic phase, extract ammonium ions in ammonium tungstate, reduce the pH value to 2-4, and digest to generate ammonium metatungstate solution.
Characteristics of ammonium metatungstate solvent extraction method
It has high sensitivity and selectivity, simple equipment, rapid operation and good separation effect. However, the extraction solvent is volatile, flammable and toxic, so be careful when operating.
Steps of ammonium metatungstate solvent extraction method
Extraction of ammonium tungstate solution → digestion to generate ammonium metatungstate solution → concentration and crystallization → filtration and separation → drying to obtain the product.
- Ammonium metatungstate smelting production method – ion exchange method
Principle of ammonium metatungstate ion exchange method
Using ammonium paratungstate as raw material, ammonium metatungstate is prepared by ion exchange method. Heat ammonium paratungstate at high temperature, adjust the product into slurry, and boil to generate ammonium metatungstate solution.
Characteristics of ammonium metatungstate ion exchange method
Using ion exchange technology, the process is relatively direct.
Steps of ammonium metatungstate ion exchange method
Heat ammonium paratungstate → adjust into slurry → boil → generate ammonium metatungstate solution → concentrate and crystallize → filter and separate → dry to obtain the product.
- Ammonium metatungstate smelting production method – electrodialysis method
Principle of ammonium metatungstate electrodialysis method
Using ammonium tungstate or ammonium paratungstate as raw material, ammonium metatungstate is prepared by electrodialysis technology. Ammonium ions enter the cathode chamber through the anion exchange membrane, increasing the concentration of ammonium metatungstate in the anode chamber.
Characteristics of ammonium metatungstate electrodialysis method
Ion separation is carried out using the principle of electrodialysis.
Steps of ammonium metatungstate electrodialysis method
Raw materials are added to the anode chamber → current passes → ammonium ions migrate → the concentration of ammonium metatungstate in the anode chamber increases → ammonium metatungstate solution is released from the cathode chamber → ammonium metatungstate is obtained by subsequent treatment.
- Ammonium metatungstate smelting production method – neutralization method
Principle of ammonium metatungstate neutralization method
Use secondary ammonium metatungstate and nitric acid as raw materials, and adjust the pH value by adding dilute nitric acid to convert ammonium metatungstate into ammonium metatungstate.
Characteristics of ammonium metatungstate neutralization method
Use acid-base neutralization reaction for conversion.
Steps of ammonium metatungstate neutralization method
Mix secondary ammonium metatungstate and nitric acid → adjust pH value → heat and dissolve → age → concentrate → filter → dry to obtain the product.
- Ammonium metatungstate smelting production method – thermal decomposition method
Principle of ammonium metatungstate thermal decomposition method
Use ammonium metatungstate as raw material, decompose and convert into ammonium metatungstate at high temperature.
Characteristics of ammonium metatungstate thermal decomposition method
Material conversion is carried out through thermal decomposition technology.
Steps of thermal decomposition method of ammonium metatungstate
Mix ammonium paratungstate and catalyst → decompose at high temperature → adjust pH value → digest → concentrate → dry to obtain the product.
- Ammonium metatungstate smelting production method – tungsten acid method
Principle of ammonium metatungstate tungsten acid method
Dissolve tungstic acid with ammonia water and convert it into ammonium metatungstate under specific conditions.
Characteristics of ammonium metatungstate tungsten acid method
Use tungstic acid as the starting material.
Steps of ammonium metatungstate tungsten acid method
Dissolve tungstic acid with ammonia water → heat to remove ammonia → adjust pH value → heat to concentrate → cool and filter → dry to obtain the product.
These methods have their own characteristics and application scenarios in the production of ammonium metatungstate, and the appropriate production method can be selected according to actual needs and conditions.
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