Fluorine (F) is a high-value resource that has been overlooked in the production of wet process phosphoric acid (WPA) due to its high susceptibility to complexation with metal cationic impurities, hindering F efficient recovery and subsequent phosphoric acid purification. This paper firstly emphasizes on investigating the competitive complexation behavior between F species and metal cations (M = Al³⁺, Fe³⁺, Ca²⁺ and Mg²⁺) by designing a series of F-containing model solutions (as HF and/or H₂SiF₆) with fixed combinations of metal cations. The results reveal that the complexation ability between metal cations and “free” F^- species from HF dissociation and/or SiF₆^2- hydrolysis follows the order: Al³⁺ > Fe³⁺ > Ca²⁺ > Mg²⁺. DFT calculation further confirms that the acid-soluble AlF₄^- and FeF₃ species with lower binding energies are the main obstacle to difficult recovery of F species in the WPA. Given the above facts, an efficient F recovery strategy is proposed by increasing initial F concentration (as HF and H₂SiF₆) in industrial WPA for preferentially removing metal impurities in the forms of M−F precipitates (e.g., AlF₃ and CaF₂), according to the variations in distributions of M−F species under different n(F)/n(M) ratios predicted through establishment of mathematical models. The ultimate F recovery rate is greater than 95% by stripping process when initial HF concentration added is about 7.49 mol/L. This novel strategy has been successfully applied in phosphoric acid purification process.

氟 (F) 是一种高价值资源，由于其高度易与金属阳离子杂质络合，阻碍了 F 的有效回收和后续磷酸纯化，因此在湿法磷酸 (WPA) 生产中一直被忽视。本文首先着重^{通过设计一系列含氟}模型溶液（如^HF和/或 H ₂ SiF ₆ ) 与金属阳离子的固定组合。结果表明，金属阳离子与“游离”F ^-_{来自 HF 解离和/或 SiF 6} ^2-水解的物质遵循以下顺序：Al ³⁺ > Fe ³⁺ > Ca ²⁺ > Mg ²⁺。DFT计算进一步证实，具有较低结合能的酸溶性AlF ₄ ^-和FeF ₃物种是WPA中F物种难以回收的主要障碍。鉴于上述事实，提出了一种有效的 F 回收策略，通过增加工业 WPA 中的初始 F 浓度（如 HF 和 H ₂ SiF ₆）优先去除 M−F 沉淀物形式的金属杂质（例如，AlF ₃和 CaF ₂),根据建立数学模型预测不同n(F)/n(M)比值下M−F物种分布的变化。当加入的HF初始浓度约为7.49 mol/L时，通过汽提工艺最终的F回收率大于95%。该新策略已成功应用于磷酸纯化过程。