The effect of particle size on the transformation kinetics of flue gas desulfurization (FGD) gypsum to α-calcium sulfate hemihydrate (α-HH) in calcium chloride (CaCl₂) solutions was investigated to better guide value-added FGD gypsum use. Gypsum samples from different sources were sieved into several size groups, and their transformation rates were compared. The results showed that using FGD gypsum with a smaller particle size accelerated the transformation to α-HH. The size effect accelerated nucleation kinetics of α-HH rather than its crystal growth rate (that is, the thermodynamic driving force for the transformation changed little with particle size variation). Analysis using a kinetics model revealed that a smaller gypsum particle size lowered the overall activation energy barrier for the transformation. This is because the smaller gypsum particles had a larger relative specific surface area and thus provided more nucleation sites and crystalline defects to promote α-HH nucleation. A smaller particle size of FGD gypsum also gave a higher yield of fine α-HH particles because of the increased incidence of primary and secondary nucleation coupled with attrition. This paper indicates the transformation of FGD gypsum into α-HH could be effectively promoted by regulating FGD gypsum particle size.

粒度对烟气脱硫（FGD）石膏在氯化钙（CaCl ₂）中转化为α-半水硫酸钙（α-HH）的转化动力学的影响）研究了解决方案，以更好地指导增值FGD石膏的使用。将来自不同来源的石膏样品筛分为几个大小组，并比较它们的转化率。结果表明，使用较小粒径的FGD石膏加速了向α-HH的转化。尺寸效应加速了α-HH的成核动力学，而不是其晶体生长速率（即，转变的热力学驱动力随粒径变化而变化很小）。使用动力学模型进行的分析表明，较小的石膏颗粒尺寸降低了转化的总体活化能垒。这是因为较小的石膏颗粒具有较大的相对比表面积，因此提供了更多的成核位点和晶体缺陷以促进α-HH成核。较小粒径的FGD石膏还可以提高α-HH细粉的产量，这是因为初级和次级成核的增加以及磨损的缘故。本文表明，通过调节烟气脱硫石膏的粒径可以有效地促进烟气脱硫石膏向α-HH的转化。