Method and apparatus used for preparing ammonium phosphate fertilizer from phosphoric acid sediment

Abstract

The invention discloses a method and an apparatus used for preparing ammonium phosphate fertilizer from phosphoric acid sediment. The method comprises following steps: the phosphoric acid sediment with a P2O5 content of 30 to 35% is mixed with diluted phosphoric acid with a concentration of 18 to 20% so as to obtain intermediate mixture I with a phosphoric acid content of 20 to 25%; the intermediate mixture I and gaseous ammonia with a concentration of 99% are subjected to neutralization reaction at a N mole / P mole ratio of 1.3-1.35, and a certain amount of sulfuric acid is added so as to neutralize unreacted gaseous ammonia; the N mole / P mole ratio is increased to 1.4-1.45 so as to obtain intermediate mixture II; and the intermediate mixture II is subjected to condensation, granulation and screening treatment. Gaseous ammonia is used for neutralizing the intermediate mixture I with a phosphoric acid content of 21 to 25%, ammonium bicarbonate or liquid ammonia are not used, and reaction contact area and reaction speed of gaseous ammonia and the intermediate mixture I are enlarged and increased respectively, so that filter-pressing washing process of the phosphoric acid sediment is simplified, comprehensive utilization of the phosphoric acid sediment is realized, and the quality of the ammonium phosphate products is improved.

Description

[0001] 1. Technical field [0002] The invention relates to a method and a device for preparing ammonium phosphate fertilizer by using phosphoric acid sediment, in particular to a method and a device for preparing ammonium phosphate fertilizer by using phosphoric acid sediment generated when phosphoric acid is prepared by a wet method. 2. Background technology [0003] Compared with thermal phosphoric acid, wet-process phosphoric acid has the advantages of low energy consumption and less pollution, and will gradually replace thermal phosphoric acid. In the production of wet-process phosphoric acid, because impurities such as iron, magnesium, and aluminum in phosphate rock will complex with phosphoric acid to produce a large amount of phosphoric acid sediment, these phosphoric acid sediments are mainly phosphate precipitates or crystals, so phosphoric acid sediment is used to produce The method and device for ammonium phosphate fertilizer are an important chemical method and ...

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Problems solved by technology

In the production of wet-process phosphoric acid, because impurities such as iron, magnesium, and aluminum in phosphate rock will complex with phosphoric acid to produce a large amount of phosphoric acid sediment, these phosphoric acid sediments are mainly phosphate precipitates or crystals, so phosphoric acid sediment is used to produce The method and device for ammonium phosphate fertilizer are an important chemical method and chemical device. In the existing method and device for producing ammonium phosphate fertilizer by using phosphoric acid sediment, the patent No. ZL97107676.6 discloses a method and device that utilizes wet method A method for producing ammonium phosphate fertilizer from phosphate waste slag, which uses ammonium bicarbonate or liquid ammonia to neutralize the acid in the phosphate slag, and the neutralized slag can be directly used as a commercial fertilizer or a raw material in a compound fertilizer after being spray-dried fertilizer, but the defect of this patent is that the phosphoric acid sediment needs to be treated with equipment such as spray dryer, cyclone separator, dust collector, etc. At the same time, the total nutrient of fertilizer is too low, generally less than 50% of the total nutrient

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