Abstract:

In order to make better use of phosphogypsum resources and paly its utmost value,using phosphogypsum powder as raw material,the content of dihydrate gypsum,anhydrite and hemihydrate gypsum were reasonably allocated after calculating the chemical composition,the content of water-soluble P₂O₅,water-soluble F^- and Cl^- were adjusted by introducing soluble P₂O₅,NaF and NaCl.The effect of phase composition and impurity content on its properties was studied by testing the setting time and mechanical properties.The results showed that when the mass fraction of dihydrate gypsum was lower than 3%,the hydration reaction of building gypsum would be accelerated,and its early strength effect could be enhanced.When the mass fraction of hemihydrate gypsum was about 77%,its mechanical properties would be better,and when the mass fraction of an-hydrite was more than 15%,its mechanical properties would decrease greatly.When building gypsum powder was prepared from phosphogypsum,the mass fraction of water-soluble P₂O₅,water-soluble F^- and Cl^- should be controlled below 0.2%,0.3% and 0.04%,respectively.From the perspective of phase composition and impurity control,this paper provides reference for the resource utilization of phosphogypsum and helps to improve the utilization level of phosphogypsum in China.

Key words: phosphorus building gypsum, phase composition, impurity control