Li(上标 +), K(上标 +)//CO3(上标 2-), B4O7(上标 2-)-H2O交互四元体系298K介稳相平衡研究

This paper reports experimental data of metastable phase equilibria and the corresponding phase diagram of the quaternary system Li(superscript +), K(superscript +)//CO3(superscript 2-), B4O7(superscript 2-)-H2O, a subsystem of the brine system of Zhabuye Salt Lake, Tibet at 298K. 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.