Method and stirring device for producing crystalline monoammonium phosphate by using wet-process purified phosphoric acid

The invention relates to the field of preparation of monoammonium phosphate, particularly a method and stirring device for producing crystalline monoammonium phosphate by using wet-process purified phosphoric acid. The method cancels the pretreatment technique required by hot-process phosphoric acid, saves the investment and simplifies the operation. The method comprises the following steps: (1) adding a preset amount of mother solution into a neutralizing tank, and adding metered purified wet-process phosphoric acid with the purity of 85% until the mass concentration of phosphoric acid in the mixed solution is 35-45%; (2) starting a stirring device, adding liquid ammonia for neutralization by multipoint ammonification, continuously adding the liquid ammonia for 80-100 minutes while controlling the liquid ammonia addition speed, and stopping neutralization when the pH value reaches 4.2-4.6; (3) sending the qualified product into a cooling crystallization stage; and (4) after finishing crystallization, dehydrating and drying the slurry to obtain crystalline monoammonium phosphate, and sending the mother solution to a mother solution storage tank for cyclic use.