The thermal decomposition method for ammonium metatungstate smelting is a method for preparing ammonium metatungstate (AMT). The specific steps are as follows:
Raw material preparation: After fully mixing ammonium paratungstate and a small amount of citric acid catalyst, it is used as the raw material for preparing ammonium metatungstate.
Thermal decomposition process
Put the mixed raw materials into a far-infrared rotary furnace.
Control the thermal decomposition temperature between 200 and 280°C.
The decomposition time is about 1 hour.
Product treatment
Some ammonia and water will be removed at this time, and the weight loss rate of ammonium paratungstate is about 5% to 6%.
The product after thermal decomposition immediately becomes slurry, and an appropriate amount of ammonia water is added to adjust the pH value to 3 to 4.
The slurry is digested at about 90°C.
Subsequent treatment
When the content of ammonium metatungstate (AMT) is 50% after evaporation and concentration, it can be sold as a liquid product.
When the evaporation concentration is 20% of the original volume, crystallization, filtration separation, granulation and other operations are carried out to finally obtain the ammonium metatungstate product. The evaporation concentrate can also be treated by spray drying to obtain ammonium metatungstate products.
The advantages of thermal decomposition include cost control, simple preparation facilities and processes, and are suitable for large-scale industrial production. However, the following points should be noted:
Operators should take personal protection measures to avoid accidental inhalation and ingestion.
Storage should be carried out in a ventilated, dry, and cool warehouse.
AMT or waste liquid shall not be discharged into the surrounding environment without government permission.
More details of ammonium metatungstate product, please visit website: http://ammonium-metatungstate.com/
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