There are several methods for the preparation of tungsten ammonium oxide hydrate (also known as tungsten ammonium oxide hydrate), and the choice of these methods depends on the specific production requirements and conditions, the following are several common preparation methods:
- Preparation method of tungsten ammonium oxide hydrate (hydrated tungsten ammonium oxide)-neutralization method
Neutralization method is a commonly used method for the preparation of tungsten ammonium oxide hydrate. The method takes ammonium sec-metatungstate and nitric acid as raw materials, and the target product is produced through a series of chemical reactions. The specific steps are as follows:
Ammonium sec-metatungstate was added to deionized water and ammonium citrate to form a slurry containing WO3 at a concentration of 12% to 30%.
Add 3%~5% dilute nitric acid to the ammonium sec-tungstate slurry according to the ratio of ammonium sec-tungstate: nitric acid=1:20, control the solid-liquid ratio of 1: (3~4), Ph value of 2~4, and heat to dissolve.
Make the solution relative density of 1.18 ~ 1.20, heating to 80 ~ 90 ℃, constant temperature and volume control Ph value, stirring reaction 4h.
After aging for a few hours, the clear solution was concentrated to about 50% WO3 content, and filtered to remove insoluble matter.
The clear liquid continues to be concentrated, cooled and crystallized, dried to 80 ℃ to produce tungsten ammonium oxide hydrate.
Second, the preparation method of tungsten ammonium oxide hydrate (hydrated tungsten ammonium oxide) – tungstic acid method
Tungstic acid method is also a method of preparing tungsten ammonium oxide hydrate. This method utilizes tungstic acid as raw material, and the target product is produced through the steps of dissolving in ammonia and adjusting pH value by acetic acid. The specific steps are as follows:
Dissolve tungstic acid with ammonia and add it to a container of boiling deionized water.
Ammonia was heated under stirring to make Ph=8.
Acetic acid was added while the solution was boiling, and then the Ph was adjusted by dilute nitric acid from 2 to 4.
Continue to heat and concentrate until the relative density of 1.5 to 2, stop heating, cooling and filtration.
The filtrate add ethanol stirred thoroughly, filtered after settling, crystals at 80 ℃ drying, crushing that is the product.
Preparation method of tungsten ammonium oxide hydrate (tungsten ammonium oxide hydrate)-thermal decomposition method
Thermal decomposition method takes ammonium paratungstate as raw material and produces tungsten ammonium oxide hydrate through thermal decomposition reaction. The specific steps are as follows:
Mix ammonium paratungstate and a small amount of citric acid catalyst thoroughly and put them into a far-infrared rotary furnace.
The thermal decomposition temperature was controlled to be 200-280 ℃, and the decomposition was carried out for about 1 h. At this time, some ammonia and water were removed. At this time, some ammonia and water were removed, and the weight loss of ammonium sec-tungstate was 5% to 6%.
After the thermal decomposition of the product immediately into a slurry, add appropriate amount of ammonia, adjust the Ph value in the range of 3 ~ 4.
The slurry is boiled at 90℃, and can be sold as liquid product when the content of ammonium metatungstate is 50% by evaporation and concentration.
When evaporation and concentration to the original volume of 20% crystallization, filtration and separation, granulation products. The evaporation concentrate can also be spray-dried to produce products.
Fourth, the preparation method of tungsten ammonium oxide hydrate (hydrated tungsten ammonium oxide) – solvent extraction method
Solvent extraction method uses organic extractant to extract ammonium ions from ammonium tungstate solution to produce tungsten ammonium oxide hydrate. Specific steps include extraction, boiling, concentration and crystallization, filtration and drying.
- Preparation method of tungsten ammonium oxide hydrate (tungsten ammonium oxide hydrate)-ion exchange method
The ion exchange method takes ammonium paratungstate as raw material and produces tungsten ammonium oxide hydrate through ion exchange reaction. The method includes the steps of heating ammonium sec-tungstate, mixing the product into slurry, boiling to generate ammonium metatungstate solution, concentration and crystallization, filtration and separation and drying.
- Preparation method of tungsten ammonium oxide hydrate (hydrated tungsten ammonium oxide) – other methods
In addition to the above several common preparation methods, there may also exist other methods for the preparation of tungsten ammonium oxide hydrate, such as solid phase method (nanopowder produced by solid phase reaction between solid particles) and so on. The selection of these methods depends on factors such as specific production conditions, product specifications and performance requirements.
The above preparation methods are only examples, and may need to be adjusted and optimized according to specific conditions during the actual production process. Meanwhile, the tungsten ammonium oxide hydrate produced by different preparation methods may differ in purity, crystalline morphology and physical properties. Therefore, when choosing the preparation method, various factors need to be considered comprehensively to ensure that the quality and performance of the product meet the requirements.
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