The raw and auxiliary materials for the preparation of ammonium metatungstate hydrate (also called ammonium metatungstate, abbreviated as AMT) mainly include the following categories:
- Main raw materials
Tungsten source
It mainly includes tungsten-containing compounds such as sodium tungstate, ammonium tungstate and ammonium paratungstate (APT). These compounds are the starting materials for the preparation of ammonium metatungstate, of which elemental tungsten is the main component of the target product.
Acid solution
In the preparation process, acid solution is used to adjust the pH value of the solution and promote the chemical reaction. Commonly used acids include hydrochloric acid, sulfuric acid and nitric acid.
Ammonia
In some preparation methods, ammonia is used to dissolve tungstic acid or adjust the pH of the solution to generate ammonium metatungstate.
- Auxiliary materials
Extractant
In the solvent extraction method, organic extractants such as di(2-ethylhexyl) phosphate (D₂EHPA) or tributyl phosphate (TBP) are used to form an organic phase with kerosene solvent, which is used to extract ammonium ions from ammonium tungstate to prepare ammonium metatungstate solution.
Ion exchange resin
In the ion exchange method, a cation exchange resin of the H+ type is used in contact with ammonium tungstate solution to exchange cations in the solution to obtain ammonium metatungstate solution.
Catalysts
In some thermal decomposition methods, a small amount of a catalyst such as citric acid may be used to facilitate the reaction.
- Other materials
Deionized water
Used for preparing slurries, dissolving raw materials, washing products, etc.
Ethanol
Used for settling and washing crystals in some preparation methods.
Other solvents and additives
Other solvents and additives may be required depending on the specific preparation method and process requirements.
Preparation Examples
An exemplary method for preparing ammonium metatungstate hydrate from ammonium tungstate solution includes:
Treating the ammonium tungstate solution with a solvent extraction method or an ion exchange method to obtain the ammonium metatungstate solution.
The ammonium metatungstate solution is subjected to evaporation and crystallization to obtain ammonium metatungstate hydrate crystals.
The crystals are post-treated by washing and drying to obtain the final product.
Precautions
In the preparation process, the reaction conditions, such as temperature, pH, reaction time, etc., need to be strictly controlled to ensure the quality and yield of the product.
The raw and auxiliary materials used should meet the relevant standards and requirements to ensure the safety and environmental protection of the product.
The waste liquid and waste gas etc. generated in the preparation process should be disposed of properly to minimize the pollution to the environment.
The raw and auxiliary materials for the preparation of ammonium metatungstate hydrate mainly include the main raw materials such as tungsten source, acid solution and ammonia, and auxiliary materials such as extractant, ion exchange resin and catalyst. The specific materials to be used depend on the preparation method and process requirements adopted.
More details of ammonium metatungstate product, please visit website: http://ammonium-metatungstate.com/
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