制备高强石膏是磷石膏资源化的重要途经。为实现磷石膏资源化,采用蒸压水溶液法,以硫酸铝、草酸钾及其共混物为转晶剂,在蒸压温度为130 ℃、保温时间为6 h、液固质量比为0.5条件下制备了α-半水石膏。讨论了不同转晶剂对α-半水石膏形貌和力学性能的影响。结果表明,以硫酸铝为转晶剂时,所制备试样的形貌随转晶剂掺量的增大呈现由针状向长柱状、小晶粒向大晶粒发展的趋势,而以草酸钾为转晶剂制备的试样形貌多为短柱状、晶粒大小不一。当转晶剂总量为石膏量的0.6%、硫酸铝与草酸钾掺量比为5∶1时所制备的石膏试样具有晶粒尺寸大、晶体形貌规整（六方状晶体）的特点,其2 h抗折强度和2 d绝干抗压强度分别可达5.88、36.90 MPa。

Preparation of high-strength gypsum is an important way to recycle phosphogypsum.In order to realize the recycling of phosphogypsum,the method of autoclaved aqueous solution was adopted by using aluminum sulfate,potassium oxalate and their complexes as crystal modifier to prepare α-hemihydrate gypsum under the conditions of autoclaved temperature of 130 ℃,holding time of 6 h and liquid-solid mass ratio of 0.5.The effect of the different crystal modifier on the morphology and mechanical properties of α-hemihydrate gypsum was discussed.The results showed that the morphology of the samples prepared by using aluminum sulfate as the crystal modifier had a tendency to develop from needle-like to long-column,small-grain to large-grain with the increase of crystal modifier content,but the morphology of the samples prepared by potassium oxalate as the crystal modifier was mostly short columnar and the grain size was different.When the total amount of crystal modifier was 0.6% of gypsum and the ratio of aluminum sulfate to potassium oxalate was 5∶1,the sample prepared by the composite crystal modifier had the characteristic of large crystal grain size and regular crystal morphology（hexagonal crystals）.The 2 h flexural strength and 2 d absolute dry compressive strength could reach 5.88 MPa and 36.90 MPa respectively.