CIESC Journal ›› 2023, Vol. 74 ›› Issue (5): 1896-1903.DOI: 10.11949/0438-1157.20230115

• Thermodynamics • Previous Articles     Next Articles

Phase equilibria and calculation of quaternary system LiCl+MgCl2+CaCl2+H2O at 323.2 K

Ke CHEN1(), Li DU1, Ying ZENG1,2(), Siying REN1, Xudong YU1,2   

  1. 1.College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, Sichuan, China
    2.Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institution, Chengdu 610059, Sichuan, China
  • Received:2023-02-15 Revised:2023-04-17 Online:2023-06-29 Published:2023-05-05
  • Contact: Ying ZENG

四元体系LiCl+MgCl2+CaCl2+H2O 323.2 K相平衡研究及计算

陈科1(), 杜理1, 曾英1,2(), 任思颖1, 于旭东1,2   

  1. 1.成都理工大学材料与化学化工学院,四川 成都 610059
    2.矿产资源化学四川省高校重点实验室,四川 成都 610059
  • 通讯作者: 曾英
  • 作者简介:陈科(1998—),女,博士研究生,chenk998@126.com
  • 基金资助:
    国家自然科学基金项目(U21A2017)

Abstract:

The solid-liquid phase equilibria of the quaternary system LiCl+MgCl2+CaCl2+H2O at 323.2 K were studied by the isothermal dissolution method. The density, refractive index and composition of liquid phase were determined experimentally. The phase diagram of the quaternary system at 323.2 K was plotted. The results show that there are two double salts LiCl·MgCl2·7H2O and 2MgCl2·CaCl2·12H2O formed in the quaternary system, belonging to a complex system. The phase diagram of this quaternary system consists of three invariant points, seven univariate curves, five crystallization fields corresponding to MgCl2·6H2O, LiCl·H2O, CaCl2·2H2O, LiCl·MgCl2·7H2O, 2MgCl2·CaCl2·12H2O. Comparing the phase diagram of the quaternary system at 323.2 K and 298.2 K, it has found that with the increase of temperature, calcium chloride is converted from CaCl2·6H2O and CaCl2·4H2O to CaCl2·2H2O, the crystallization fields of LiCl·MgCl2·7H2O and MgCl2·6H2O decrease and the crystallization fields of LiCl·H2O and 2MgCl2·CaCl2·12H2O increase, which indicates that increasing temperature is beneficial to the precipitation of LiCl·H2O and 2MgCl2·CaCl2·12H2O. The solubility of the quaternary system was calculated by using the PSC model, and the calculated results were basically consistent with the experimental results.

Key words: phase equilibria, aqueous solution, solubility, thermodynamic properties, lithium salt

摘要:

采用等温溶解平衡法开展了323.2 K四元体系LiCl+MgCl2+CaCl2+H2O的固液相平衡研究,测定了平衡液相组成及密度、折射率,并绘制了相应的相图。研究发现:323.2 K时,该体系有复盐LiCl·MgCl2·7H2O和2MgCl2·CaCl2·12H2O生成,属于复杂四元体系,其相图包含3个共饱点,7条单变量曲线,5个结晶区(MgCl2·6H2O、LiCl·H2O、CaCl2·2H2O、LiCl·MgCl2·7H2O、2MgCl2·CaCl2·12H2O)。对比298.2 K下该四元体系的相图,发现随着温度升高,氯化钙从CaCl2·6H2O、CaCl2·4H2O转化成CaCl2·2H2O,LiCl·MgCl2·7H2O和MgCl2·6H2O结晶区减小,LiCl·H2O和2MgCl2·CaCl2·12H2O结晶区增大,表明温度升高有利于LiCl·H2O和2MgCl2·CaCl2·12H2O析出。采用PSC模型对该四元体系进行了溶解度计算,计算结果与实验结果基本吻合。

关键词: 相平衡, 水溶液, 溶解性, 热力学性质, 锂盐

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