Method for producing diammonium phosphate by concentrating acid slime, and secondary ammoniation reactor

Abstract

This invention discloses a method for producing di-ammonium phosphate by concentration of acidic slurry. The method comprises: (1) performing a first ammonification on diluted phosphoric acid to obtain an acidic slurry of ammonium dihydrogen phosphate; (2) concentrating so that the water content is 13-20%; (3) performing a second ammonification so that the neutralization degree is increased to 1.30-1.50; (4) performing further ammonification so that the neutralization degree reaches 1.60-1.90; (5) granulating and controlling the water content at 2-4%. The mol. ratio of P to N in ammonium dihydrogen phosphate is 0.32-0.40.

Description

technical field [0001] The invention belongs to the field of diammonium phosphate production, in particular to a method for producing diammonium phosphate by concentrating slurry and equipment for secondary ammonification. Background technique [0002] Chinese patent ZL92106621.X discloses a production method of diammonium phosphate. The process steps are: a. neutralize the dilute phosphoric acid and ammonia gas once to make the neutralization degree reach 1.1-1.2; b. concentrate the slurry and reduce the water content. to 30%; c. The concentrated slurry overflows to the neutralization tank for secondary neutralization reaction with gas ammonia, so that the neutralization degree of the slurry is increased to 1.5-1.8, and the moisture is reduced to about 25%, and the tank material is neutralized The temperature of the slurry is 100-110°C; d. The slurry after the secondary neutralization reaction is sent to the spray granulation dryer for granulation and drying. Though said m...

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Problems solved by technology

[0003] 1. The degree of neutralization of the slurry in the concentration operation is relatively high, so the moisture content of the concentrated slurry is high, not only the drying energy consumption is large, but also the spray granulation drying process can only be used in the subsequent process;

[0004] 2. Due to the high drying temperature of the spray granulation process, not only can ammonia be added during the granulation process, but also the amount of ammonia escaped from the material during the drying process is large, and the nitrogen-phosphorus ratio of the product cannot reach the index of traditional diammonium phosphate (DAP) fertilizers;

[0005] 3. The secondary neutralization of the concentrated slurry uses a tank reactor with a large ammonia loss

[0008] 2. Once the phosphoric acid is neutralized to the neutralization degree of the product, the amount of ammonia escape is large;

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