The steps of thermal decomposition of ammonium metatungstate can be clearly divided into the following stages:
- Preparation stage
Raw material preparation: The main raw material is ammonium paratungstate (APT), which is usually mixed with a small amount of citric acid catalyst.
Equipment preparation: Prepare high-temperature furnace (such as far-infrared rotary furnace), high-temperature test tube, magnetic stirrer and other experimental or production equipment.
- Thermal decomposition stage
Mixing and placement: After fully mixing ammonium paratungstate and citric acid catalyst, put them into the high-temperature furnace.
Temperature control**: Control the thermal decomposition temperature between 200 and 280℃** and maintain it for a period of time (such as about 1 hour) to ensure that the reaction is fully carried out.
- Product processing stage
Impurity removal: At this time, some ammonia and water will be removed, and the weight loss rate of ammonium paratungstate is about 5% to 6%.
pH value adjustment: The product after thermal decomposition is immediately slurried, and an appropriate amount of ammonia water is added to adjust the pH value to 3 to 4.
Digestion: Digest the slurry at about 90℃ to further transform and stabilize the product.
- Concentration and crystallization stage
Evaporation concentration: The digested slurry is evaporated and concentrated until the content of ammonium metatungstate (AMT) reaches about 50%.
Crystallization and separation: When the evaporation concentration reaches **20%** of the original volume, crystallization and filtration separation are carried out to obtain ammonium metatungstate crystals.
- Drying and finished product stage
Drying: The obtained ammonium metatungstate crystals are dried at 80℃ to remove excess moisture.
Granulation and packaging: Granulation is carried out as needed, and packaging methods such as inner plastic and outer iron barrels are used. The net weight of each barrel can be 50 kg or 25 kg.
- Precautions
Temperature control: Accurate control of thermal decomposition temperature is the key to ensuring product quality.
Personal protection: Since ammonium metatungstate is a hazardous chemical, operators should take personal protection.
The thermal decomposition method of ammonium metatungstate achieves efficient conversion from ammonium paratungstate to ammonium metatungstate by accurately controlling conditions such as temperature, time and pH value. The method has clear steps and is easy to operate, is suitable for large-scale industrial production, and can obtain high-quality and high-purity ammonium metatungstate products.
More details of ammonium metatungstate product, please visit website: http://ammonium-metatungstate.com/
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