Method for preparing aluminum hypophosphite via continuous reaction crystallization process

Abstract

The invention relates to a method for preparing aluminum hypophosphite via a continuous reaction crystallization process. According to the technical scheme, the method comprises the following steps: continuously adding a 50-80wt% sodium hypophosphite solution and 50-60wt% soluble aluminum salt solution into a reaction crystallizer, controlling the average residence time of the materials in the continuous reaction crystallizer for 1 to 5 hours, further discharging a mother liquor I of aluminum hypophosphite from the bottom of the crystallizer and sending the mother liquor I of aluminum hypophosphite into an ager for aging 0 to 3 hours, then further discharging the mother liquor I from the bottom of the ager, and carrying out centrifugal separation, washing and drying so as to obtain an aluminum hypophosphite crystal with the purity greater than 99.0% and a crystallized mother liquor II; finally, evaporating and crystallizing the crystallized mother liquor II so as to obtain a coarse product sodium salt and a crystallized mother liquor III; returning the crystallized mother liquor III into the continuous reaction crystallizer for circulating. Based on the continuous reaction crystallization process, the method has the advantages of simple process, moderate operating condition, low energy consumption, stable aluminum hypophosphite quality and the like, and is easy to industrialize.

Description

technical field [0001] The invention belongs to the technical field of preparation of fine chemicals, and in particular relates to a method for preparing aluminum hypophosphite by using a continuous reaction crystallization method. Background technique [0002] Aluminum hypophosphite (Aluminum hypophosphite, Al(H 2 PO 2 ) 3 ), is a white powdery solid / crystal with a special smell, slightly soluble in water, but insoluble in alcohol. Aluminum hypophosphite is a new type of flame retardant. Because of its high phosphorus content, it has the advantages of good thermal stability, low water solubility, and high flame retardant effect. According to the UL94 standard, the thickness is 0.7 mm, and its flame retardant grade is VO, and according to the IEC61335-1 standard at 800 ° C, the thickness is greater than 0.8 mm, passed the GWIT test, and all passed various flame retardant grade inspections. [0003] The preparation method of aluminum hypophosphite is mainly divided into t...

AI Technical Summary

Problems solved by technology

The raw material hypophosphorous acid of method (1) is volatile, and hypophosphorous acid steam has very big harm to operator and environment; Although method (2) has solved the problem of hypophosphorous acid volatilization in method (1), but existing Method (1) and method (2) in the open literature of the present invention all adopt batch process, and its degree of automation is low, and single set of device production capacity is small, and production cycle is long, and product quality is not stable, is unfavorable for the large-scale production of aluminum hypophosphite

Moreover, in the preparation methods of aluminum hypophosphite disclosed in CN 102786041 A and CN103145110 A, the crystallization mother liquor after filtering out aluminum hypophosphite is not treated, and the crystallization mother liquor is rich in the by-product Na2 SO4 and NaNO3