含钾水盐体系介稳相关系研究  

An Experimental Study on Metastable Phase Equilibrium of the Potassium Solid-liquid System

作　　者：彭芸[1] 曾英[1] 于旭东[1] 张龙钦[1] 吴祎[1] 冯珊[1] 

机构地区：[1]成都理工大学材料与化学化工学院,成都610059

出　　处：《地质学报》2010年第11期1697-1703,共7页Acta Geologica Sinica

基　　金：国家自然科学基金(40673050);新世纪优秀人才支持计划(NCET-08-0900)联合资助成果

摘　　要：针对西藏扎布耶盐湖卤水组成,采用等温蒸发法分别研究了含钾四元体系Na+,K+//Cl-,B4O27--H2O308.15K、五元体系K+//Cl-,CO23-,SO42-,B4O72--H2O273.15K下的介稳相关系。分别测定了上述体系308.15K、273.15K时介稳平衡液相组成及密度、pH值。根据实验数据绘制了相应的介稳相图、水图。结果表明,本文研究的两个体系均为简单共饱型,无复盐和固溶体生成。其中,四元体系介稳相图由2个共饱点,5条单变量曲线,4个结晶区组成。平衡固相分别为Na2B4O7.10H2O、K2B4O7.4H2O、NaCl和KCl。对比四元体系308.15K和273.15K下的介稳相图发现,平衡固相盐的种类及结晶形式均没有发生变化,但结晶区大小产生变化:在308.15K下,Na2B4O7.10H2O结晶区变小,K2B4O7.4H2O结晶区变大。五元体系投影图中有1个共饱点、3条单变量曲线和3个结晶相区。结晶相区分别为K2CO3.3/2H2O、K2SO4和KCl。K2CO3.3/2H2O结晶区面积最小,K2SO4结晶区面积最大。K2CO3对KCl有较强的盐析作用。In accordance with the composition of the Zabuye salt lake brine,Tibet,the metastable phase equilibrium of the quaternary system Na＋,K＋//Cl-,B4O2-7-H2O at 308.15 K and quinary system K＋//Cl-,CO2-3,SO2-4,B4O2-7-H2O at 273.15 K were studied.Solubilities and physicochemical properties such as density and pH value of equilibrium solutions were determined at research temperature.On the basis of the experimental data,the metastable equilibrium phase diagram and the water diagram were plotted.The results show that both the quaternary and quinary systems are of a simple eutectic type,neither double salt nor solid solution is formed at research temperatures.In the quaternary system,the phase diagram consists of two invariant points,five uninvariant curves,and four crystallization regions.The four crystallization regions correspond to salts Na2B4O7·10H2O,K2B4O7·4H2O,NaCl and KCl,respectively.Comparing the metastable phase diagrams of the quaternary system at 273.15 K and 308.15 K,it shows that the crystallization forms and the crystallization field of salts have no change,whereas the area of the crystallization field has changed.At 308.15 K,the crystallization field of salt Na2B4O7·10H2O becomes smaller,whereas that of salt K2B4O7·4H2O becomes larger.In the quinary system,the projection diagram（saturated with K2B4O7·4H2O）consists of one invariant point,three univariant curves,and three crystallization fields corresponding to the single salts K2CO3·3/2H2O,K2SO4 and KCl（and saturation of K2B4O7·4H2O）.The crystallization field of salt K2CO3·3/2H2O is the smallest,whereas that of salt K2SO4 is the biggest.Salt K2CO3 has a strong salting-out effect to salt KCl.

关 键 词：介稳相平衡 钾 硼酸盐 溶解度 

分 类 号：O642.42[理学—物理化学]