LAUSR

Using FGD gypsum as the raw material, whitening and large prismatic dihydrate gypsum can be obtained by dissolution-crystallization and decoloring process with α-hemihydrate gypsum whiskers prepared in MgSO4-CaCl2-H2O solution, which can transform into whitening short columnar α-hemihydrate gypsum. The effects of aging temperature, pH, dosage of sodium dodecyl sulfonate (SDS), time on composition and morphology of products were investigated. The research shows that: whitening and large prismatic dihydrate gypsum with average length of 350μm and the whiteness of 82.57% can be obtained with 6g SDS (mass ratio of SDS/FGD gypsum was 1.2) addition and pH of 8 after 3.5h under 60°C. The effects of different morphologies of dihydrate gypsum on α-hemihydrate gypsum were discussed, which indicates that granularity and morphology of α-hemihydrate gypsum are directly related to dihydrate gypsum. And short columnar α-hemihydrate gypsum with the length of 100μm and the whiteness of 85.68% can be prepared by dihydrate gypsum obtained under optimum conditions mentioned above.