338.15 K时四元体系CaCl2-SrCl2-BaCl2-H2O相平衡测定及溶解度计算

采用等温溶解平衡法研究338.15 K时三元体系CaCl₂-SrCl₂-H₂O、CaCl₂-BaCl₂-H₂O和SrCl₂-BaCl₂-H₂O的稳定相平衡，进一步研究四元体系CaCl₂-SrCl₂-BaCl₂-H₂O的相平衡。根据实验数据，分别绘制了三元体系的相图和密度-组成图，四元体系空间立体图、相图、水图和密度-组成图。研究结果表明：CaCl₂-SrCl₂-BaCl₂-H₂O四元体系在338.15 K时没有复盐和固溶体生成，稳定平衡相图由1个共饱点、3条单变量溶解度曲线，3个结晶区组成，分别对应BaCl₂·2H₂O结晶区、SrCl₂·mH₂O（m=2，6）结晶区和CaCl₂·2H₂O结晶区。采用DFT模型进行338.15 K三元体系CaCl₂-SrCl₂-H₂O、CaCl₂-BaCl₂-H₂O和SrCl₂-BaCl₂-H₂O的溶解度计算，计算结果与实验结果基本吻合。针对CaCl₂-SrCl₂-BaCl₂-H₂O四元体系及三元子体系的稳定相平衡研究，可为综合开发利用油田卤水中的钙-锶-钡资源提供数据基础。

Phase equilibria determination and solubility calculation of the quaternary system CaCl2-SrCl2-BaCl2-H2O at 338.15 K

The stable phase equilibria of ternary system CaCl₂-SrCl₂-H₂O, CaCl₂-BaCl₂-H₂O and SrCl₂-BaCl₂-H₂O at 338.15 K were studied by isothermal dissolution equilibrium method, and then the quaternary system CaCl₂-SrCl₂-BaCl₂-H₂O was studied. According to the experimental data, the phase diagram and density composition diagram of ternary system, the space diagram, phase diagram, water diagram and density composition diagram of quaternary system were drawn respectively. The results show that there is no double salt or solid solution in the quaternary system CaCl₂-SrCl₂-BaCl₂-H₂O. The stable phase diagram of the quaternary system consists of one invariant saturation point, three univariate solubility curves and three salt crystallization regions at 338.15 K, corresponding to the crystallization regions of BaCl₂·2H₂O, SrCl₂·mH₂O(m=2,6) and CaCl₂·2H₂O respectively. The solubility of the ternary system CaCl₂-SrCl₂-H₂O, CaCl₂-BaCl₂-H₂O and SrCl₂-BaCl₂-H₂O at 338.15 K were calculated by DFT model. The calculated results are basically consistent with the experimental data. The study of stable phase equilibria of quaternary and ternary systems of CaCl₂-SrCl₂-BaCl₂-H₂O can provide data basis for comprehensive development and utilization of calcium-strontium-barium resources in oilfield brine.