摘要
卤水体系中LiCl富集度较高,且高纯度LiCl在工业上有广泛的应用,因Na^(+)和Li^(+)的性质相似,除去卤水中的NaCl成为了生产高纯度LiCl的瓶颈。Li^(+),Na^(+)∥Cl^(-)-H_(2)O三元体系的固液相平衡数据是分离LiCl和NaCl必需的重要基础数据。采用等温溶解平衡法研究了常压下Li^(+),Na^(+)∥Cl^(-)-H_(2)O三元体系的固液相平衡关系(348.15、358.15、363.15 K)并构建等温平衡相图。结果表明,不同温度下的相图均由一个共饱点、两个单盐结晶区(NaCl和LiCl·H_(2)O)及两条单变量溶解度曲线构成,未形成复盐或固溶体。随着温度的升高,NaCl的结晶区略有扩大,而LiCl·H_(2)O的结晶区变化很小。LiCl对NaCl有较强的盐析作用。采用修正的BET模型对相平衡数据进行了关联,结果良好,验证了该模型适用于预测本体系在高温、高浓度下的相平衡关系。测量了该体系饱和溶液密度并由密度值计算了表观摩尔体积,结果表明,密度随LiCl组成的增加先减小后增大,在共饱点组成处达到最大值。这些结果补充了Li^(+),Na^(+)∥Cl^(-)-H_(2)O体系在高温下的热力学数据,对脱除Na^(+)精制LiCl起到基础性的指导作用。
The enrichment of LiCl in brine system is high,and high⁃purity LiCl is widely used in industry.Because of the similar properties of Na^(+)and Li^(+),the removal of NaCl from brine has become the difficulty of producing high⁃purity LiCl.The solid⁃liquid equilibrium data of Li^(+),Na^(+)∥Cl^(-)-H_(2)O ternary system is an important basic data for the separation of LiCl and NaCl.The solid⁃liquid phase equilibrium relationship of ternary system of Li^(+),Na^(+)∥Cl^(-)-H_(2)O at 348.15 K,358.15 K and 363.15 K under atmospheric pressure was investigated by an isothermal dissolution equilibrium method and the equilibrium phase diagram was constructed.The results showed that the phase diagrams at different temperatures were composed of one eutectic invariant point,two single salt crystallization fields(NaCl and LiCl·H_(2)O)and two univariate solubility curves,and it formed neither double salt nor solid solution.With the increase of the temperature,the crystallization region of NaCl was expanded slightly,while the crystal region of LiCl·H_(2)O was changed little.LiCl had a strong salting⁃out effect on NaCl.The modified BET model was used to correlate the phase equilibrium data,and the correlation value was in good agreement with the experimental value,indicating that the model was more suitable for predicting phase equilibrium relation in this water⁃salt system at high temperature and high concentration.The density of the saturated solution of the system was measured and the apparent molar volume was calculated from the density value.The results showed that the density was decreased at first and then increased with the increase of LiCl composition,and reached the maximum at the co⁃saturation point.These results supplemented the thermodynamic data of Li^(+),Na^(+)∥Cl^(-)-H_(2)O system at high temperature and played a basic guiding role in the removal of Na^(+)and purification of LiCl.
作者
王彦飞
杨超凡
曹迪
许史杰
WANG Yanfei;YANG Chaofan;CAO Di;XU Shijie(Tianjin Key Laboratory of Brine Chemical Engineering and Ecological Utilization of Resources,Tianjin 300457,China;College of Chemical Engineering and Materials,Tianjin University of Science and Technology,Tianjin 300457,China)
出处
《无机盐工业》
CAS
CSCD
北大核心
2024年第1期33-39,共7页
Inorganic Chemicals Industry
基金
中国国家重点研究发展计划项目(2022YFC2904000)
国家自然科学基金项目(Nos.NNSFC 22178272和NNSFC 22108204)
《大学长江学者和创新研究团队培训计划》项目([2013]373)
天津市教委创新研究团队项目(TD13-5008)
中国大学长江学者与创新研究团队项目(IRT-17R81)。
关键词
氯化锂
氯化钠
固液相平衡
修正的BET模型
表观摩尔体积
lithium chloride
sodium chloride
solid⁃liquid equilibrium
fixed BET model
apparent molar volume
