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为了精确预测非理想条件下稀土金属溶剂萃取的平衡分配比,研究了溶于ShellsolD70中的P507溶剂对盐酸液中钇(Ⅲ)和铕(Ⅲ)的萃取平衡,建立化学基模型,并通过非线性最小二乘法确定萃取平衡常数。所建模型涉及了在低酸度区的离子交换反应和高酸度区的溶剂化萃取反应;模型还考虑了稀土金属与Cl-的配位反应,并用萃取剂的有效浓度代替[(HR)2],进而分别对水相和有机相(HR)2的非理想性加以修正。对稀土单元体系,在较宽的初始浓度范围内(稀土浓度最高至0.1mol/L,盐酸浓度0.07-3.00mol/L,萃取剂浓度0.25-1.00mol/L),由模型计算的稀土分配比与实验测得的数据吻合良好,验证了模型的有效性。对于稀土二元体系,该模型能以良好的精度对平衡分配比进行工程预测。
In order to accurately predict the equilibrium distribution ratio of rare earth metal solvent extraction under non-ideal conditions, the extraction equilibrium of yttrium (Ⅲ) and europium (Ⅲ) in hydrochloric acid solution by P507 solvent dissolved in Shellsol D70 was studied. The chemical basis model was established, Linear least squares method to determine extraction equilibrium constant. The model involved the ion exchange reaction in low acidity region and the solvation reaction in high acidity region. The model also considered the coordination reaction between rare earth metal and Cl- and replaced [(HR) 2] with the effective concentration of extractant , And then the water phase and the organic phase (HR) 2 non-ideality be amended. For the rare-earth element system, the Rare Earth distribution ratio calculated by the model is within a wide range of initial concentration (the concentration of rare earth is up to 0.1mol / L, the concentration of hydrochloric acid is 0.07-3.00mol / L, the concentration of extractant is 0.25-1.00mol / L) The results are in good agreement with the experimental data, which verifies the validity of the model. For rare earth binary systems, the model predicts the equilibrium distribution ratio with good accuracy.