化工学报

• •    

锂钠镁共存硫酸盐体系多温相图及其应用研究

赵志星1(), 姚智豪1, 于雪峰2, 杨游胜1, 曾英1,3, 于旭东1,3()   

  1. 1.成都理工大学材料与化学化工学院,四川 成都 610059
    2.青海盐湖工业股份有限公司,青海 格尔木 816000
    3.矿产资源化学四川省高校重点实验室,四川 成都 610059
  • 收稿日期:2024-02-05 修回日期:2024-03-21 出版日期:2024-03-25
  • 通讯作者: 于旭东
  • 作者简介:赵志星(1998-),男,硕士,zhaozhoxingc413@126.com
  • 基金资助:
    四川省科技计划资助(2022YFQ0075)

Multi-temperature phase diagram of lithium-sodium-magnesium coexistence sulfate system and its application

Zhixing ZHAO1(), Zhihao YAO1, Xuefeng YU2, Yousheng YANG1, Ying ZENG1,3, Xudong YU1,3()   

  1. 1.College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059, Sichuan, China
    2.Qinghai Salt Lake Industry Co. , Ltd. , Golmud 816000, Qinghai, China
    3.Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institution, Chengdu 610059, Sichuan, China
  • Received:2024-02-05 Revised:2024-03-21 Online:2024-03-25
  • Contact: Xudong YU

摘要:

针对硫酸钠亚型盐湖卤水钠锂比高、镁锂比高带来的锂分离难题,通过开展锂钠镁共存硫酸盐体系多温相图研究,获取锂钠镁硫酸盐之间的作用关系和结晶析出规律,并应用于指导降低卤水中钠镁含量工艺设计。采用等温溶解平衡法获取了四元体系Li+, Na+, Mg2+//SO42- - H2O 303.2、318.2 K固液相平衡数据,采用X-ray粉晶衍射法(XRD)测定了共饱点的平衡固相类型。复盐分析:采用X-ray粉晶衍射法(XRD)、扫描电镜(SEM)和热重分析法(TG-DSC)进行了各复盐的晶体结构分析、晶体形貌表征和热分析。研究发现:四元体系Li+, Na+, Mg2+//SO42- - H2O 303.2、318.2 K下均为复杂体系,相图均包含4个四元共饱点、9条单变量曲线和6个结晶区。303.2 K时,该体系相图结晶区为:Na2SO4、Na2SO4·10H2O、Li2SO4·H2O、MgSO4·7H2O、Na2SO4·MgSO4·4H2O、Li2SO4·3Na2SO4·12H2O;318.2 K时,该体系相图结晶区为:Na2SO4、MgSO4·7H2O、Li2SO4·H2O、Na2SO4·MgSO4·4H2O、Li2SO4·Na2SO4、Li2SO4·3Na2SO4·12H2O。对比该四元体系288.2、298.2、303.2、318.2、323.2 K多温相图发现:温度对体系的影响主要表现在水合盐和含锂复盐的结晶形式及各盐类结晶区面积的变化。根据四元体系多温相图中含锂复盐(Li2SO4·Na2SO4、Li2SO4·3Na2SO4·12H2O)、白钠镁矾(Na2SO4·MgSO4·4H2O)和三元体系Na+, Mg2+//SO42- - H2O多温相图中盐类的结晶规律,给出了硫酸钠亚型盐湖脱钠镁及白钠镁矾的分离加工建议。

关键词: 相平衡, 溶液, 溶解性, 白钠镁矾, 含锂复盐

Abstract:

In order to solve the problem of lithium separation caused by high ratio of sodium to lithium and high ratio of magnesium to lithium in sodium sulfate subtype salt lake brine, the multi-temperature phase diagram of lithium-sodium-magnesium coexistence sulfate system was studied to obtain the action relationship and crystallization precipitation law of lithium-sodium-magnesium sulfate. It is applied to guide the process design of reducing the content of sodium and magnesium in brine. The solid-liquid phase equilibria for the quaternary systems Li+, Na+, Mg2+//SO42- - H2O at 303.2 and 318.2 K were studied by using isothermal dissolution equilibrium method. The solid phases of invariant points were verified by X-ray diffraction method (XRD). The crystal structure, crystal morphology and thermal analysis of the double salts were analyzed by X-ray diffraction method (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TG-DSC). Results show that both these systems are complex systems, and their phase diagrams consist of these quaternary systems consist of four invariant points, nine isothermal dissolution curves, and six crystallization regions. The crystallization regions of the phase diagram of the system at 303.2 K is Na2SO4, Na2SO4·10H2O, Li2SO4·H2O, MgSO4·7H2O, Na2SO4·MgSO4·4H2O, Li2SO4·3Na2SO4·12H2O; 318.2 K is Na2SO4, Li2SO4·H2O, MgSO4·7H2O, Na2SO4·MgSO4·4H2O, Li2SO4·3Na2SO4·12H2O, Li2SO4·Na2SO4. By comparing the multi-temperature phase diagrams of the quaternary system at 288.2, 298.2, 303.2, 318.2 and 323.2 K, it is found that the effect of temperature on the system is mainly manifested in the crystallization form of hydrated salts and lithium-containing double salts and the change of crystallization areas of each salts. Combined with the crystallization rules of lithium-containing double salts (Li2SO4·Na2SO4, Li2SO4·3Na2SO4·12H2O), astrakhanite (Na2SO4·MgSO4·4H2O) in Quaternary system and the crystallization rules of salts in ternary system Na+, Mg2+//SO42- - H2O, some suggestions for the separation and processing of sodium sulfate subtype salt lake removal sodium (magnesium) and astrakhanite separation process were given.

Key words: phase equilibria, solution, solubility, astrakhanite, lithium-containing double salt

中图分类号: