The process flow of preparing ammonium metatungstate hydrate by ion exchange method can be clearly divided into the following steps, which are summarized with relevant figures and information:
- Preparation of raw materials
Ammonium paratungstate (APT) is selected as the starting raw material.
- Ion exchange process
Adjustment of pH value
Adjust the pH value of ammonium paratungstate solution or ammonium tungstate solution to a range suitable for ion exchange, usually around pH 3.5.
Ion exchange resin selection
Use strong acid or weak acid H+ type cation resin, such as commercially available specific type resin, to ensure that the resin has high selectivity and exchange capacity.
Performing ion exchange
Ammonium sec-tungstate solution with adjusted pH is passed through the ion exchange column, and H+ in the resin is exchanged with NH4+ in the solution. In this process, the resin adsorbs ammonium ions and releases hydrogen ions into the solution. The exchanged solution contains a high concentration of metatungstate ions (WO4^2-) and hydrogen ions (H+), forming a metatungstate solution.
III. Cooking and conversion
Cooking process
The exchanged metatungstic acid solution is boiled at a specific temperature, usually the temperature is controlled at 98℃, and the boiling time is 5 hours. The purpose of this step is to make the tungstate ion in the solution further transformed into stable ammonium metatungstate under the action of hydrogen ion.
Fourth, evaporation concentration and crystallization
Evaporation and concentration
The solution of ammonium metatungstate after boiling is evaporated and concentrated to remove excess water and increase the concentration of ammonium metatungstate in the solution.
Crystallization
The concentrated solution is cooled and crystallized or spray dried to precipitate ammonium metatungstate in the form of crystals. The crystals obtained in this step are ammonium metatungstate hydrate.
- Filtration and drying
Filtration
Use filtration equipment to separate the crystallized ammonium metatungstate hydrate from the mother liquor to get wet crystals.
Drying
Dry the wet crystals to remove the residual water and solvent, and get the dried ammonium metatungstate hydrate product.
Resin regeneration and recycling
Resin regeneration
The resin saturated by NH4+ can be regenerated by hydrochloric acid solution or other appropriate regeneration agent to restore its exchange capacity.
Recycling
The regenerated resin can be reused in the ion exchange process to realize the recycling of resources.
The process flow of preparing ammonium metatungstate hydrate by ion exchange method includes the steps of raw material preparation, ion exchange, boiling and conversion, evaporation, concentration and crystallization, filtration and drying, as well as resin regeneration and recycling. This method has the advantages of simple process, convenient control and high product purity, which is one of the important methods for the preparation of ammonium metatungstate hydrate. Meanwhile, through the regeneration and recycling of resin, effective saving of resources and friendly protection of environment can be realized.
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
