Phosphogypsum (PG) is a typical by-product of phosphoric acid and phosphate fertilizers during acid digestion. The application of cemented paste backfill (CPB) has been feasibly investigated for the remediation of PG. The present study evaluated fluorine immobilization mechanisms and attempted to construct a related thermodynamic and geochemical modeling to describe the related stabilization performance. Physico-chemical and mineralogical analyses were performed on PG and hardened PG-based CPB (PCPB). The correlated macro- and micro-structural properties were obtained from the analysis of the combination of unconfined compressive strength and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy imaging. Acid/base-dependent leaching tests were performed to ascertain fluoride reachability. In addition, Gibbs Energy Minimization Software and PHREEQC were applied as tools to characterize the PCPB hydration and deduce its geochemical characteristics. The results proved that multiple factors are involved in fluorine stabilization, among which the calcium silicate hydrate gel was found to be associated with retention. Although the quantitative comparison with the experimental data shows that further modification should be introduced into the simulation before being used as a predictive implement to determine PG management options, the importance of acid/base concentration in regulating the leaching behavior was confirmed. Moreover, the modeling enabled the identification of the impurity phases controlling the stability and leachability.

磷石膏 (PG) 是磷酸和磷肥在酸消化过程中的典型副产品。水泥浆回填 (CPB) 的应用已被研究用于修复 PG。本研究评估了氟固定机制，并试图构建相关的热力学和地球化学模型来描述相关的稳定性能。对 PG 和硬化 PG 基 CPB (PCPB) 进行了物理化学和矿物学分析。相关的宏观和微观结构特性是通过分析无侧限抗压强度和扫描电子显微镜以及能量色散 X 射线光谱成像的组合而获得的。进行了依赖酸/碱的浸出测试以确定氟化物的可达性。此外，Gibbs 能量最小化软件和 PHREEQC 被用作表征 PCPB 水化并推断其地球化学特征的工具。结果证明，氟稳定涉及多种因素，其中发现硅酸钙水合物凝胶与保留有关。尽管与实验数据的定量比较表明，在用作确定 PG 管理选项的预测工具之前，应在模拟中引入进一步的修改，但证实了酸/碱浓度在调节浸出行为中的重要性。此外，建模能够识别控制稳定性和浸出性的杂质相。