化工学报 ›› 2021, Vol. 72 ›› Issue (6): 3170-3178.DOI: 10.11949/0438-1157.20201690

• 青海盐湖资源综合利用专栏 • 上一篇    下一篇

四元体系(Li+, Mg2+//Cl-, borate-H2O)308.15 K相平衡与相图研究

李栋婵1(),王嘉宇1,王士强1,2()   

  1. 1.河北工业大学化工学院,天津 310029
    2.天津科技大学海洋与环境学院,天津 300457
  • 收稿日期:2020-11-25 修回日期:2021-03-05 出版日期:2021-06-05 发布日期:2021-06-05
  • 通讯作者: 王士强
  • 作者简介:李栋婵(1982—),女,博士,副教授,dongchanli@126.com
  • 基金资助:
    国家自然科学基金项目(22078247);河北省重点研发计划项目(19251804D)

Phase equilibria and phase diagram of the quaternary system (Li+, Mg2+//Cl-, borate-H2O) at 308.15 K

LI Dongchan1(),WANG Jiayu1,WANG Shiqiang1,2()   

  1. 1.School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 310029, China
    2.College of Marine and Environmental Sciences, Tianjin University of Science and Technology, Tianjin 300457, China
  • Received:2020-11-25 Revised:2021-03-05 Online:2021-06-05 Published:2021-06-05
  • Contact: WANG Shiqiang

摘要:

采用等温溶解平衡法,开展四元体系Li+, Mg2+//Cl-, borate–H2O固液相平衡与相图研究,测定平衡溶液的液相组成、密度、折射率和pH。该四元体系相图中存在的盐类矿物为:LiCl·H2O、Li2B4O7·3H2O、 MgCl2·6H2O、Mg2B6O11·15H2O和锂光卤石LiCl·MgCl2·7H2O,其中锂光卤石LiCl·MgCl2·7H2O是异成分复盐,溶液中MgCl2存在下章氏硼镁石(MgB4O7·9H2O)不稳定,转化为多水硼镁石(Mg2B6O11·15H2O)。多水硼镁石结晶区最大,表明镁硼酸盐易于结晶析出,而锂光卤石结晶区最小。采用Pitzer热力学模型对该四元体系的溶解度进行理论预测,计算相图与实验相图吻合较好。该四元体系的稳定相平衡与相图研究,可为含锂硼盐湖老卤中锂、镁、硼产品开发及其综合利用提供理论依据。

关键词: 盐湖卤水体系, 相平衡与相图, 锂盐, 镁硼酸盐, Pitzer模型

Abstract:

Solid-liquid phase equilibria and phase diagrams for the quaternary system (Li+, Mg2+//Cl-, borate–H2O) were investigated, and the compositions in liquid phase, densities, refractive indices and pH were measured experimentally by using isothermal dissolution equilibrium method. There are five minerals corresponding to LiCl·H2O, Li2B4O7·3H2O, MgCl2·6H2O, Mg2B6O11·15H2O, and the lithium carnallite LiCl·MgCl2·7H2O existed in this system. Mg2B6O11·15H2O occupies the greatest part of phase region, while LiCl·MgCl2·7H2O covers the smallest. The mineral LiCl·MgCl2·7H2O belongs to the incongruent double salt, and hungchaoite (MgB4O7·9H2O) is transformed into Mg2B6O11·15H2O in the concentrated MgCl2 aqueous solution. The crystalline area of inderite is the largest, indicating that magnesium borate is easy to crystallize, while the crystalline area of lithium carnallite is the smallest. The solubility of this quaternary system were predicted using Pitzer thermodynamics model, and the calculated solubility agreed well with experimental data. The phase equilibrium study of this quaternary system (Li+, Mg2+//Cl-, borate-H2O) will provide a theoretical basis to promote the development of lithium, magnesium and boron products and to guide the comprehensive utilization of this precious salt lake brine resources.

Key words: salt lake brine system, phase equilibria and phase diagram, lithium salts, magnesium borate, Pitzer model

中图分类号: