三元体系Na+(Mg^(2+)),Ca^(2+)//Cl^(-)-H_(2)O 278.2 K稳定相平衡研究  

Study on phase equilibria of aqueous ternary system of Na+(Mg^(2+)),Ca^(2+)∥Cl^(-)-H_(2)O at 278.2 K

作　　者：冯霞 于雪峰 姚智豪 罗军 任思颖 赵志星 于旭东[1] FENG Xia;YU Xuefeng;YAO Zhihao;LUO Jun;REN Siying;ZHAO Zhixing;YU Xudong(College of Materials and Chemistry&Chemical Engineering,Chengdu University of Technology,Chengdu 610059,China;Qinghai Salt Lake Industry Co.,Ltd.,Golmud 816099,China)

机构地区：[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816099

出　　处：《无机盐工业》2024年第1期47-52,共6页Inorganic Chemicals Industry

基　　金：四川省科技计划资助项目(2022YFQ0075);油气藏地质及开发工程国家重点实验室项目(PLC20210502)。

摘　　要：含钠镁钙水盐体系的多温相平衡研究,可为含钙镁盐湖资源的持续开发提供数据支撑。因此,采用等温溶解法开展了两个三元体系Na+,Ca^(2+)//Cl^(-)-H_(2)O和Mg^(2+),Ca^(2+)//Cl^(-)-H_(2)O在278.2 K下的相平衡研究,测定了溶解度、折射率和密度,并绘制了相应的相图。结果表明,三元体系Na+,Ca^(2+)//Cl^(-)-H_(2)O和Mg^(2+),Ca^(2+)//Cl^(-)-H_(2)O在278.2 K时均为简单体系,无复盐或固溶体生成。三元体系Na+,Ca^(2+)//Cl^(-)-H_(2)O在278.2 K时的氯化钠结晶区远大于氯化钙,对比该体系273.2、278.2、298.2、348.2 K多温相图可知,随温度升高,氯化钠结晶区增大,氯化钙结晶形式由CaCl_(2)·6H_(2)O转变为CaCl_(2)·2H_(2)O。三元体系Mg^(2+),Ca^(2+)//Cl^(-)-H_(2)O在278.2 K时的MgCl_(2)·6H_(2)O结晶区大于CaCl_(2)·6H_(2)O,对比该体系273.2、278.2、303.2、308.2、348.2、383.2 K多温相图发现:303.2、308.2、348.2、383.2 K时体系中形成复盐2MgCl_(2)·CaCl_(2)·12H_(2)O,且其结晶区随温度升高而增大;383.2 K时体系中同时存在两种复盐2MgCl_(2)·CaCl_(2)·12H_(2)O和MgCl_(2)·2CaCl_(2)·6H_(2)O。Study on the multitemperature phase equilibria of water⁃salt system containing sodium,magnesium and calcium can provide data support for the sustainable development of salt lakes containing magnesium and calcium.Therefore,the phase equilibria of two aqueous ternary system of Na+,Ca^(2+)∥Cl^(-)-H_(2)O and Mg^(2+),Ca^(2+)∥Cl^(-)-H_(2)O at 278.2 K were investi⁃gated by the isothermal dissolution method,the solubility,refractive index and density of these two systems were deter⁃mined,the corresponding phase diagrams were constructed based on the experimental data.The results showed that Na+,Ca^(2+)∥Cl^(-)-H_(2)O and Mg^(2+),Ca^(2+)∥Cl^(-)-H_(2)O were both belong to simple system without double salts or solid solution formed at 278.2 K.The crystallization regions of NaCl was much larger than CaCl_(2)·6H_(2)O in the system Na+,Ca^(2+)∥Cl^(-)-H_(2)O at 278.2 K,comparing the phase diagrams of the system at 273.2,278.2,298.2,348.2 K,it could be seen that with the increase of tem⁃perature,the crystallization area of NaCl was increased,and the crystal form of CaCl_(2)was changed from CaCl_(2)·6H_(2)O to CaCl_(2)·2H_(2)O.The crystallization region of MgCl_(2)·6H_(2)O was larger than CaCl_(2)·6H_(2)O in the system Mg^(2+),Ca^(2+)∥Cl^(-)-H_(2)O at 278.2 K,comparing the phase diagrams of the system at 273.2,278.2,303.2,308.2,348.2,383.2 K,it was found that the double salt tachyhydrite 2MgCl_(2)·CaCl_(2)·12H_(2)O was formed at 303.2,308.2,348.2,383.2 K,and its crystallization region was increased with the increase of temperature.There were two double salts of 2CaCl_(2)·MgCl_(2)·6H_(2)O and 2MgCl_(2)·CaCl_(2)·12H_(2)O formed at 383.2 K.

关 键 词：相平衡 相图 溶解度 水合盐 

分 类 号：O642.42[理学—物理化学]