Traditional Way Producing Ammonium Paratungstate
Traditional way to produce ammonium paratungstate (APT) is the main APT production way used in many manufacturers, with its advantages of simple process and easy to operate. However, unavoidable, it has its shortcomings, such as long process, high energy consumption ect.. The steps of traditional way producing ammonium paratungstate are like bellow:
1. Acid or alkali method to deal with tungsten concentrate to dissolve tungsten into the solution, thus to get crude sodium tungstate solution;
2. The sodium tungstate solution is carried out acid decomposition to get tungstic acid;
3. Dissolve tungstic acid with ammonia water to get ammonium tungstate solution;
4. Evaporation and crystallization the ammonium tungstate solution to get APT.
An invention of England has pointed out a way to produce APT, which is obtaining tungsten acid pulp by mixing 150kgs tungstic acid and 125kgs water, adding 60L 25% of ammonia water under the condition of keeping the pH value of solution at 7; stirring for 1 hour at 80°C, then get APT by evaporation and crystallization. Researchers have found that the different water used in adding tungstic acid pulp will affect the APT crystallization latter, which is the more dilute tungstic acid pulp will bring the larger crystal particle, and the more water soluble ammonium paratungstate, thereby the recovery rate of tungsten will be less.