Phosphogypsum (PG), as a waste by-product with high content and complicated impurities, is difficult to be utilised effectively. Herein, cleaner PG is prepared with “HClH₂SO₄ method”, and thus is used to synthesise α-hemihydrate gypsum (α-HH) in CaCl₂ solution under atmospheric pressure. Morphology and mechanical strength are controlled by introducing varying dosages of modifier (0–0.06 wt% of the PG). Results show that reaction time extends from 120 min to 390 min and average length/diameter (L/D) ratio of α-HH crystal is decreased from 10.3 to 0.6 with the increase in the modifier dosage from 0 to 0.045 wt%. When the modifier dosage is 0.04 wt%, the converted product shows the best mechanical performance and fine commercial application prospect. The impurity content of α-HH synthesised from cleaner PG significantly decreases to approximately 5% of that from traditional PG. The mechanical strength of α-HH prepared from cleaner PG is better than that from traditional PG. The work presents a new and practical method to utilise PG efficiently.

磷石膏（PG）作为高含量，复杂杂质的废副产物，难以得到有效利用。这里，清洁剂PG通过“ HCl H ₂ SO ₄法”制备，因此用于在CaCl _2中合成α-半水石膏（α-HH）。溶液在大气压下。通过引入不同剂量的改性剂（PG的0–0.06 wt％）来控制形态和机械强度。结果表明，随着改性剂用量从0到0.045 wt％的增加，反应时间从120分钟延长至390分钟，α-HH晶体的平均长度/直径（L / D）比从10.3降低至0.6。当改性剂的用量为0.04wt％时，转化产物显示出最佳的机械性能和良好的商业应用前景。由清洁剂PG合成的α-HH的杂质含量显着降低至传统PG的5％左右。用清洁剂PG制备的α-HH的机械强度要好于传统PG。这项工作提出了一种新的实用方法来有效利用PG。