Ammonium metatungstate hydrate production and extraction methods mainly include solvent extraction or ion exchange method with ammonium tungstate solution as raw material, solvent extraction method with sodium tungstate solution as raw material, heated thermal dissociation APT method, neutralization method, tungstic acid method, and thermal decomposition method. In all ammonium metatungstate production processes, the main process parameters or control points are no more than, relative density of the solution, pH, temperature, reaction time and so on.
The important process parameters or control points in the production process of ammonium metatungstate hydrate mainly include the following aspects:
- Neutralization method
pH value
In the neutralization method, the control of pH value is crucial. It is usually necessary to control the pH value in the range of 2 to 4 to ensure that the reaction between ammonium sec-tungstate and nitric acid proceeds smoothly to produce ammonium metatungstate.
Temperature
The control of temperature is also critical in the process of heating dissolution and stirring reaction. It is usually necessary to heat the solution to 80-90°C to promote the reaction.
Stirring speed
Stirring speed has an effect on the homogeneity and efficiency of the reaction, and it needs to be controlled appropriately to ensure that the reactants are fully mixed.
- Tungstic acid method
pH value
In tungstic acid method, it is also necessary to control the pH value. After adding acetic acid, use dilute nitric acid to adjust the pH value to 2~4, which is the key to ensure the subsequent reaction proceeds smoothly.
Temperature
In the process of heating and concentration, the control of temperature has an important impact on the quality and yield of the product. Usually need to heat the solution to a certain temperature, so that its relative density reaches 1.5 ~ 2 when the heating is stopped.
Third, thermal decomposition method
Thermal decomposition temperature
In thermal decomposition method, the control of thermal decomposition temperature is the key. Usually it is necessary to control the temperature in the range of 200～280℃ to ensure that ammonium sec-tungstate and citric acid catalyst fully react to produce ammonium metatungstate.
Stirring and cooking decomposition
After the product of thermal decomposition is made into slurry, it is necessary to add appropriate amount of ammonia, adjust the pH value in the range of 3 to 4, and cook the slurry at 90℃. In this process, stirring and cooking conditions have an important impact on the quality and yield of the product.
Fourth, solvent extraction and ion exchange method
pH
In the solvent extraction method and ion exchange method, the control of pH value is equally important. It is usually necessary to reduce the pH value to 2 to 4 to ensure the smooth running of the extraction or exchange process.
Reaction Temperature and Time
Reaction temperature and time are also key parameters in solvent extraction and ion exchange. Appropriate reaction temperature and time need to be controlled to ensure the efficiency of the reaction and the quality of the product.
- Electrodialysis
Current and voltage
In electrodialysis method, the control of current and voltage is the key. Appropriate current and voltage need to be controlled to ensure that ammonium ions enter the cathode chamber through the anion exchange membrane, thus increasing the concentration of ammonium metatungstate in the anode chamber.
In summary, important process parameters or control points in the production process of ammonium metatungstate hydrate include pH, temperature, stirring speed, thermal decomposition temperature, stirring and cooking conditions, reaction temperature and time, current and voltage. The control of these parameters or control points has an important influence on the quality and yield of the product, so it needs special attention.
More details of ammonium metatungstate product, please visit website: http://ammonium-metatungstate.com/
Please contact CHINATUNGSTEN for inquiry and order of ammonium metatungstate:
Email: sales@chinatungsten.com
Tel.: 86 592 5129595
