Abstract: Phosphogypsum is a kind of industrial solid waste, which is discharged when the phosphoric chemical industry produces phosphoric acid through the wet process. Because phosphogypsum contains a large amount of impurities such as phosphorus, fluorine, and alkali metal salts, it will be disposed of in a landfill, which will cause problems such as occupation of cultivated land and environmental pollution. At present, the most promising and effective treatment method is to convert phosphogypsum to α-hemihydrate gypsum (α-HH). But the harmful impurities such as soluble phosphorus, eutectic phosphorus and soluble fluorine of phosphogypsum are the main obstacles to the preparation of α-HH from phosphogypsum. Therefore, the pretreatment of harmful impurities in phosphogypsum and the adjustment of α-HH crystal morphology are the focus of research on the preparation of α-HH from phosphogypsum. This article comprehensively reviewed the physicochemical properties of phosphogypsum, the influences of harmful impurities on the properties of gypsum, the pretreatment measures, the preparation method of α-HH and the adjustment of crystal micromorphology, and the current research status. Different pretreatment measures and the preparation methods of α-HH were discussed. The advantages and disadvantages of the method were summarized, and the mechanism of the crystal transformation agent regulating the micro-morphology of α-HH crystals was summarized. Finally, the next problem to be solved was put forward.

Key words: phosphogypsum, impurity, pretreatment, α-hemihydrate gypsum, preparation method, transforming agent, crystal morphology, adsorption mechanism