The process flow of preparing ammonium metatungstate can be summarized as follows.
- Preparation of raw materials
Ammonium paratungstate (APT): as the main raw material, its purity and quality directly affect the quality of the final product.
Nitric acid: used to convert ammonium paratungstate into ammonium metatungstate, usually using dilute nitric acid, the concentration of which is controlled at 3% to 5%.
Deionized water: Used for preparing slurry and washing products to ensure purity to remove impurities.
Ammonium citrate (optional): as an auxiliary solvent, used to adjust the viscosity and stability of the slurry.
Second, the preparation of slurry
Add ammonium paratungstate into deionized water and ammonium citrate to formulate slurry with WO₃ 12%-30% concentration.
Neutralization reaction
According to the ratio of ammonium paratungstate: nitric acid=1:20, add 3%~5% dilute nitric acid into the ammonium paratungstate slurry.
Control the solid-liquid ratio of 1: (3 ~ 4), Ph value of 2 ~ 4, heating and dissolution, so that the relative density of the solution to 1.18 ~ 1.20.
In the appropriate stirring speed, heating to 80 ~ 90 ℃, constant temperature and volume control Ph value, stirring reaction for 4 hours.
Fourth, aging and filtration
Aging for several hours, so that the substances in the solution fully react and precipitate.
Through filtration equipment, remove the insoluble matter in the solution to get clear ammonium metatungstate solution.
- Concentration and crystallization
Concentrate the clear solution until the WO₃ content is about 50%.
The concentrated solution is cooled down, so that ammonium metatungstate crystals are precipitated.
Drying and crushing
Dry the crystallized ammonium metatungstate at 80°C to remove excess water.
The dried ammonium metatungstate is crushed to get the final ammonium metatungstate product.
Combining batch, inspection and packing
Combining batch, inspection and packaging of ammonium metatungstate is a process involving several steps. Combining batches of ammonium metatungstate usually refers to mixing ammonium metatungstate from different batches or sources according to a certain proportion or method to achieve the expected chemical properties, physical properties or production requirements. The specific operation of batch mixing may vary depending on factors such as production process and product usage. Inspection and packaging will be carried out after batch mixing.
VIII. Precautions
During the whole process, special attention must be paid to controlling the temperature, pH value, stirring speed and other parameters to ensure the activity of the reactants during the production process to ensure the quality of the final product.
The operators need to have sufficient experience and a strict quality management system to ensure the quality of ammonium metatungstate meets the requirements. Specific equipment, such as centrifuges, mixers, evaporators, etc., are also required to improve production efficiency.
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
