Characteristics and mechanism of desulfurization gypsum to α-hemihydrate gypsum:Experiments and simulations
The efficient utilization of desulfurized gypsum can effectively alleviate a series of environmental problems and turn waste into treasure.This paper used dihydrate gypsum to prepare α-hemihydrate gypsum in ethylene glycol aqueous solution containing trace anhydrous sodium sulfate,and explored the effects of temperature(94-98℃),ethylene glycol volume fraction(25%—35%),sodium sulfate concentration(0.1-0.3mol/L)on the mole fraction of α-hemihydrate gypsum and kinetic parameters in the dehydration conversion process from dihydrate gypsum to α-hemihydrate gypsum.The results showed that in ethylene glycol aqueous solution,the dehydration conversion process of dihydrate gypsum to α-hemihydrate gypsum conformed to the dispersion kinetic model.With the increase of temperature and ethylene glycol concentration,the kinetic parameter α remained basically unchanged,while the parameter β increased significantly,leading to an increase in the activation entropy(∆S*),which in turn led to a decrease in the energy barrier(Ea)and promoted the dehydration of dihydrate gypsum to α-hemihydrate gypsum.The addition of a small amount of anhydrous sodium sulfate significantly shortened the nucleation induction time of α-hemihydrate gypsum.Through molecular dynamics simulation,with increasing the concentration of sodium sulfate,the coordination number of Na+and SO42-increased,and the absolute difference of diffusion coefficient ∆D decreased,resulting in the increase of coordination ability and the decrease of decoupling ability.This study was of great significance for efficient utilization of desulfurized gypsum and mastering its conversion characteristics to α-hemihydrate gypsum.
国家科技期刊平台
NSTL
万方数据
