Research on crystal regulation and growth mechanism of α-hemihydrate gypsum prepared by phosphogypsum
The sodium citrate was used as a crystal modifier to study the crystal form control method and crystal growth mechanism of α-hemihydrate gypsum prepared from phosphogypsum.The results indicate that sodium citrate has a significant effect on the short columnar growth of α-hemihydrate gypsum.Under the conditions of temperature 140 ℃,time 60 min,solid-liquid ratio 1∶2 and sodium citrate content 0.40％,high-strength α-hemihydrate gypsum can be prepared which have uniform crystal size,smooth and complete surface and crystal aspect ratio less than 1.Research on crystal growth processes at different reaction temperatures and time suggests that the formation of α-hemihydrate gypsum follows the dehydra-tion-dissolution-recrystallization mechanism,and the dissolution of dihydrate gypsum and crystallization of hemihydrate gypsum occur synchronously.The complete crystal growth can be completed within 5 min.
phosphogypsumα-hemihydrate gypsumcrystalline controlmechanism of growth
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