Abstract: In order to address the issues of low heat transfer efficiency and high energy consumption in traditional phosphogypsum calcination processes,this study explores efficient and low-consumption resource utilization technologies for phosphogypsum to produce high-quality Type Ⅱ anhydrite. Using a calcination process,it systematically investigates the influence of calcination temperature,time,and method on product performance. The product characteristics were characterized using X-ray diffraction (XRD),Fourier transform infrared spectroscopy ( FTIR),and scanning electron microscopy ( SEM). The optimal process conditions were determined to be suspension calcination at 700 ℃ for 60 minutes. Under these conditions,the product achieved a Type Ⅱ anhydrite content of 90. 49%,residual crystal water content of 0. 48%,and whiteness value of 91. 8%. All indicators comply with the Treatment and Disposal Specifications for Phosphogypsum (GB/ T 32124—2024). Compared to static calcination,suspension calcination significantly enhances product purity and whiteness while reducing crystal water content. The transformation mechanism of phosphogypsum to Type Ⅱ anhydrite was elucidated. The suspension calcination process provides an efficient and feasible technical pathway for the high-value utilization of phosphogypsum,and the related findings hold significant theoretical and practical value. 

Key words: phosphogypsum,type Ⅱ anhydrite gypsum,suspension calcination,water of crystallisation,whiteness