Study On The Crystallization Process Of Zinc Sulfate Heptahydrate

Zinc sulfate heptahydrate is an important inorganic chemical product,which is widely used in industry,agriculture and other fields.However,there are still some problems existing during the manufacturing process in domestic factories such as unpleasant crystal size distribution and undesired crystal size.Addressing these issues,the thermodynamics,kinetics,crystal morphology and crystallization process were studied thoroughly in this research.The equilibrium method was used to measure the solubility of Zinc sulfate in water at different temperatures,and the ABC model,the ?h model and the vant hoff model were applied to fit the solubility of Zinc sulfate.In order to optimize the operational conditions,the metastable zone and the induction period of Zinc sulfate heptahydrate were measured.The single crystals of zinc sulfate heptahydrate and hexahydrate were cultivated successfully and the crystal structures were obtained through X-ray single crystal diffraction.The two crystal habits were simulated through BFDH model,and the morphology comparison of the two single crystals were discussed.A novel microemulsion method was applied to fabricate monodisperse zinc sulfate heptahydrate hollow spheres with high crystallinity.The formation mechanism of the new morphology was discussed,as well as the influencing factors.At last,the effects of the initial concentration,the seed,the cooling rate and stirring speed on the crystal size and the crystal size distribution of zinc sulfate heptahydrate were studied to optimize operational conditions.The crystal size and crystal size distribution of the optimized products were superior to those of the original products.