15℃时K^+、Na^+、Mg^(2+)//Cl^-、SO_4^(2-)-H_2O五元体系介稳相平衡研究

METASTABLE PHASE EQUILIBRIUM OF K^+, Na^+, Mg^(2+)//Cl^-,SO_4^(2-)-H_20 QUINARY SYSTEM AT 15℃

模拟青海察尔汉盐湖的自然气候条件,测定了K^(+)、Na^(+)、Mg^(2+)//Cl^-、SO_4^(2-)-H_2O五元体系在温度15±0.1℃、风速3.5～4.0m/s、空气相对湿度35%～40%以及蒸发速率2～4mm/d条件下的介稳相平衡数据,绘出了该五元体系的介稳相图.利用HW公式计算了该五元体系在15℃时的介稳相平衡数据,计算值同实验值吻合较好.

The experimental data of metastable phase equilibrium of K+,Na+, Mg2+//Cl-, SO42--H2O quinary system at the conditions of temperature 15± 0.1℃, air flowing velocity 3.5-4.0m/s, air relative humidity 35-40%, and evaporation rate 2-4 mm/24h is presented. From these metastable equilibrium data, a metastable phase diagram is drawn. It consists of eight regions of crystallization saturated with sodium chloride: potassium chloride, glasserite, schoenite, carnallite, thenardite epsomite, magnesium sulfate hexahydrate, and bischofit. A model of the K+, Na+, Mg2+ // Cl-, SO42--H2O quinary system is deve theloped for calculating the metastable phase equilibrium. This model utilizes activity coefficient expressions of Harvie and Weare. The calculated data of metastable phase equilibrium fit well with the experimental data.