Ammonium Paratungstate Neutralization Crystallization Principle

Ammonium paratungstate neutralization crystallization method refers to a fixed-form process. In this process, atoms or molecules are highly organized into a structure called a crystal.

Some forms of crystal formation are by precipitation from the solution, after the hot saturated solution is cooled, the solute can precipitate as crystals. Ammonium paratungstate neutralization crystallization principle is: at room temperature with hydrochloric acid and ammonium tungstate constantly neutralizing solution, and then allowed to settle for a period of time after precipitation of ammonium paratungstate crystals. Ammonium paratungstate neutralization crystallization process in the chemical reaction formula is:

12(NH₄)₂WO₃+14HCl+(n-7)H₂O=5(NH₄)₂O·12WO₃·nH₂O+14NH₄Cl

The neutralization crystallization of ammonium paratungstate is carried out by slowly dripping dilute hydrochloric acid having a concentration of 10% to 20% into a rapidly stirred ammonium tungstate solution. This is to avoid ammonium tungstate solution, the local high acidity lead to the generation of metatungstate. When the solution is neutralized to p H = 7.0 ~ 7.5 can be stopped. After the solution is allowed to stand 8 ~ 12h, the crystallization rate of the solution can reach 90% ~ 95%. The crystals are washed with deionized water and the crystals of ammonium paratungstate are obtained after precipitation. When the temperature of the neutralization crystallization of ammonium paratungstate is room temperature, it is possible to obtain a needle-shaped APT product containing 11 parts of crystal water with a small particle size.

Crystallization of ammonium paratungstate prepared by the neutralization crystallization method of ammonium paratungstate has a long grain reaction time at room temperature, though the grain size is small. However, the product may be mixed with Cl-. Hydrochloric acid easily corrode equipment, hydrochloric acid consumption, and will leave a lot of volume of the mother liquor. If the tungsten acid dubbed a certain concentration of tungstic acid slurry, and then add ammonia to adjust its p H value to 7 or so, we can get ammonium paratungstate, ammonium paratungstate size with the size of the amount of water when the preparation of tungstic acid slurry changes.

• < Prev
• Next >