Abstract:

Agglomeration phenomenon often occurs in the reaction crystallization process,which is one of the main factors af-fecting the particle size,morphology and other properties of the product.Focusing on the agglomeration phenomenon of calci-um hydrogen phosphate,the process steps of agglomeration were analyzed,and the main impurities that hinder the agglomera-tion in industrial production were explored.The results showed that large,uniform and stable calcium hydrogen phosphate particles were obtained by using pure dilute phosphoric acid as raw material.The large-size aggregates undergone three key growth steps: single crystals agglomeration,small-size cluster crystals agglomeration and large-size cluster spherical crystal morphology formation.The colloidal particles containing fluorine in crystallization mother solution blocked the second step of agglomeration and became the most important factor to prevent agglomeration.Exploring the technological method of rationally utilizing the agglomeration phenomenon will open up a new way to solve the problems of difficult filtration and high drying cost in the industrial production of feed-grade calcium hydrogen phosphate.

Key words: large-size particles of calcium hydrogen phosphate, agglomeration, colloidal particles containing fluorine, crystallization