Li^+,K^+//CO_3^(2-),B_4O_7^(2-)-H_2O交互四元体系298 K介稳相平衡研究

Metastable Phase Equilibria of the Quaternary Reciprocal System Li^+,K^+//CO_3^(2-),B_4O_7^(2-)-H_2O at 298 K

我国西藏扎布耶盐湖卤水中蕴藏的锂、钾、硼等资源是如此之丰富,实属世界罕见。该盐湖卤水体系可简化为K^＋,Na^＋,Li^＋//B4O7^2-,CO3^2-,HCO3^-,Cl^-,SO4^2--H2O。而Li^＋,K^＋//CO3^2-,B4O7^2--H2O是该多元体系的一个四元子体系。对扎布耶盐湖卤水体系中特征体系及子体系开展多温稳定和介稳相平衡研究。不仅可以对这类复杂水盐体系化学行为的理论和实验描述提供科学依据．而且对于从该盐湖卤水中提取锂、钾、硼等有用成分的工艺过程制定和设计具有重要的现实意义。

This paper reports experimental data of metastable phase equilibria and the corresponding phase diagram of the quaternary system Li^＋,K^＋//CO3^2-,B4O7^2--H2O,a subsystem of the brine system of Zhabuye Salt Lake,Tibet at 298 K.The results indicate that this quaternary system is of simple eutecyic-type and no double salt or solid solution is formed.The isothermal diagram consists of two invariant points,five univariant curves and four crystallization fields.These fields correspond to K2B4O7·4H2O,K2CO3·3/2H2O,Li2B4O7·5H2O and Li2CO3 salts,respectively.It is found that：（1） under the metastable equilibrium conditions the crystallization species of K2B4O7·4H2O,K2CO3·3/2H2O,and Li2CO3 are the same as those under the stable equilibrium ones,（2） Li2B4O7·3H2O found in the stable equilibrium case is replaced by Li2B4O7·5H2O in the metastable equilibrium conditions,so does the crystallization region in the phase diagram.