Method for preparing phosphoric acid raffinate based diammonium phosphate

Abstract

The invention relates to a method for preparing phosphoric acid raffinate based diammonium phosphate. The technical scheme of the invention is as follows: the method comprises the steps: adding waterinto phosphoric acid raffinate in accordance with that a mass ratio of the phosphoric acid raffinate to the water is 1: (0.1 to 0.3), and carrying out stirring for 0.5 to 1 hour, so as to obtain diluted phosphoric acid raffinate; adding urea into the diluted phosphoric acid raffinate in accordance with that a mass ratio of the urea to the diluted phosphoric acid raffinate is (0.5 to 2): 1, carrying out stirring at a temperature of 70 DEG C to 100 DEG C until a pH value is 6 to 7, and carrying out solid-liquid separation, so as to obtain purified phosphoric acid raffinate and trash residues; washing the trash residues with water, so as to obtain washed trash residues and washing water; returning the washing water to the step (1) for diluting the phosphoric acid raffinate; and concentratingthe purified phosphoric acid raffinate until the content of P2O5 is 40wt% to 50wt%, then, introducing the concentrated phosphoric acid into a tubular reactor, and controlling a neutralization degree to be 1.8 to 2.0, thereby obtaining the phosphoric acid raffinate based diammonium phosphate. The method has the characteristics that the operating environment is good, the filtering is easy, and the phosphorus loss rate of an impurity removal process is low while no new impurity is introduced.

Description

technical field [0001] The invention belongs to the technical field of phosphoric acid raffinate. Specifically relates to a preparation method of diammonium phosphate based on phosphoric acid raffinate. Background technique [0002] Wet production of phosphoric acid has low energy consumption and strong adaptability of raw materials, and has been widely used in the preparation of different phosphorus products. However, in the wet extraction process, a large amount of impurities such as Fe, Al, Mg and other ions enter the leachate with phosphorus, which makes it difficult to separate phosphorus and impurity ions in the subsequent process. Due to the advantages of high efficiency and good selectivity in the wet production of phosphoric acid, the solvent extraction process has been widely used in the preparation of high-purity phosphoric acid in recent years. Although the solvent extraction process has significant economic benefits, there are still two main problems: the one ...

AI Technical Summary

Problems solved by technology

Although the solvent extraction process has significant economic benefits, there are still two main problems: the one is that the phosphorus is extracted and the impurity ions are enriched during the extraction process, the viscosity of phosphoric acid raffinate is very large, and a large amount of colloidal precipitates occur. Cause filtration very difficult; The 2nd, phosphoric acid raffinate still contains the phosphorus of certain concentration, is commonly used to produce agricultural monoammonium phosphate or diammonium phosphate, but the content of impurity ions such as Fe, Al, Mg is very high, causes the phosphorus that follow-up process prepares Product purity is not up to standard

This process uses a conventional neutralizer-ammonia to treat phosphoric acid raffinate phosphoric acid, and the impurity removal effect is good, but there are still three problems: one is that a large amount of colloidal precipitates are difficult to filter during the impurity removal process; the other is that the loss of phosphorus is large, Generally, it reaches 25-30%. The third is to use ammonia gas to remove impurities. It is difficult to avoid the escape of ammonia gas from the reactor during the operation process, and the operating environment in laboratories and industrial sites is relatively poor.

This process adds surfactants to wet-process phosphoric acid, but the surfactants only have the effect of reducing viscosity and making sediment easier to filter, and cannot remove impurity ions

[0007] In summary, the existing phosphoric acid raffinate treatment technology mainly has technical defects such as poor operating environment, difficult filtration of sediment, high phosphorus loss rate and introduction of new impurities.

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