A New Dissolution Process for Ammonium Paratungstate / Tungsten Trioxide

At present, ammonium paratungstate can completely dissolve for 1~4 hours at a temperature of 120~160°C with high concentration of ammonia, some enterprises promote the decomposition of ammonium paratungstate and even through high temperature roasting to get tungsten oxide, then ammonium tungstate solution is dissolved in ammonia water, and some enterprises use sodium hydroxide and other strong alkali to dissolve ammonium paratungstate. The ammonium tungstate solution is regenerated from sodium tungstate solution, the process is complex and costly. Therefore, it is necessary to develop a new low-cost and simple dissolution process for ammonium paratungstate / tungsten trioxide.

Some scholars have published the rapid dissolution method of ammonium paratungstate / tungsten trioxide to solve the problems of high energy consumption, long time consuming, complex process and poor operating environment. It has the advantages of energy saving, simple process and good operating conditions. The specific steps are as follows:

(1) The extractants (amines, quaternary ammonium salts, phosphates, alcohols, ketones), modifiers (para octanol, TBP) and solvents (sulfonated kerosene, kerosene, toluene) are obtained in organic phase, and the volume ratio of extractants, regulators and solvents are 0.5~85%, 0~70% and 0~95% respectively.

(2) The mixture of ammonium paratungstate or tungsten trioxide, 500~700mL organic phase and 50~80mL concentration of 50~80mL to 0.1~18mol/L is mixed for 1~20 minutes at 0~100°C, so that ammonium paratungstate or tungsten trioxide can be dissolved completely, the dissolved aqueous and oil phase mixtures are obtained.

(3) Adding 200~300mL 0.1~20mol/L regeneration agent to the mixture, stirring at room temperature for 10~20 minutes, the organic phase was regenerated and tungstate solution was obtained.

(4) The organic phase and tungstate solution were separated and the organic phase returned to the dissolution process and tungstate solution was used as the product.

By adjusting the dissolution reaction system, the structure of ammonium paratungstate / tungsten trioxide is destroyed. Under the action of extracting organic phase, the tungsten is transferred to the organic phase in the solution, which reduces the free concentration of tungsten in the water phase, promotes the decomposition of ammonium paratungstate / tungsten trioxide. Tungsten completely decomposes and tungsten enters the organic phase to form tungsten organic compounds.

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