학술논문
三元体系Na+(Mg2+),Ca2+∥Cl--H2O 278.2 K稳定相平衡研究 / Study on phase equilibria of aqueous ternary system of Na+(Mg2+),Ca2+∥Cl--H2O at 278.2 K
Document Type
Academic Journal
Author
冯霞; 于雪峰; 姚智豪; 罗军; 任思颖; 赵志星; 于旭东; FENG Xia; YU Xuefeng; YAO Zhihao; LUO Jun; REN Siying; ZHAO Zhixing; YU Xudong
Source
无机盐工业 / Inorganic Chemicals Industry. 56(1):47-52
Subject
Language
Chinese
ISSN
1006-4990
Abstract
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+,Ca2+∥Cl--H2O和Mg2+,Ca2+∥Cl--H2O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+,Ca2+∥Cl--H2O和Mg2+,Ca2+∥Cl--H2O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+,Ca2+∥Cl--H2O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CaCl2·6H2O转变为CaCl2·2H2O.三元体系Mg2+,Ca2+∥Cl--H2O在278.2 K时的MgCl2·6H2O结晶区大于CaCl2·6H2O,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2MgCl2·CaCl2·12H2O,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2MgCl2·CaCl2·12H2O和MgCl2·2CaCl2·6H2O.
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+,Ca2+∥Cl--H2O and Mg2+,Ca2+∥Cl--H2O 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+,Ca2+∥Cl--H2O and Mg2+,Ca2+∥Cl--H2O 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 CaCl2·6H2O in the system Na+,Ca2+∥Cl--H2O 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 CaCl2 was changed from CaCl2·6H2O to CaCl2·2H2O.The crystallization region of MgCl2·6H2O was larger than CaCl2·6H2O in the system Mg2+,Ca2+∥Cl--H2O 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 2MgCl2·CaCl2·12H2O 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 2CaCl2·MgCl2·6H2O and 2MgCl2·CaCl2·12H2O formed at 383.2 K.
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+,Ca2+∥Cl--H2O and Mg2+,Ca2+∥Cl--H2O 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+,Ca2+∥Cl--H2O and Mg2+,Ca2+∥Cl--H2O 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 CaCl2·6H2O in the system Na+,Ca2+∥Cl--H2O 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 CaCl2 was changed from CaCl2·6H2O to CaCl2·2H2O.The crystallization region of MgCl2·6H2O was larger than CaCl2·6H2O in the system Mg2+,Ca2+∥Cl--H2O 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 2MgCl2·CaCl2·12H2O 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 2CaCl2·MgCl2·6H2O and 2MgCl2·CaCl2·12H2O formed at 383.2 K.