围绕富钾锂镁硫酸盐型卤水中，由于镁、硫酸盐的影响，形成加工过程中非目标性复盐多、钾锂等有效成分分离难度大的问题，开展Li+, K+, Na+, Mg2+//Cl-, SO42--H2O体系在低温下的相平衡、变温介稳相平衡以及非平衡态成盐规律的研究。研究内容包括Li+, K+, Na+, Mg2+//Cl-, SO42- -H2O体系及其相关子体系，在-15℃，氯化钠饱和条件下的相平衡；所涉及的重要盐类的变温非平衡态成盐和变温介稳相平衡，以及二者之间的内在联系；通过研究离子作用参数与温度的关系，建立适用于低温的相平衡热力学计算模型。通过上述研究，解决硫酸镁亚型含钾锂盐湖卤水体系中，低温对单、复盐结晶竞争能力和相关系的影响；盐类变温非平衡态成盐规律与变温介稳相图之间的内在联系等科学问题。为实现富钾锂镁硫酸盐型盐湖开发过程中选择性定向成盐、强化有效成分富集分离、优化盐湖化工工艺提供理论依据。

In processing of the brine with high concentrations of sulfate, magnesium, potassium and lithium, due to the effects of sulfate and magnesium, there are some problems such as formation of other double salts, separating difficultly for potassium and lithium, etc.. Aiming to these problems, the phase equilibrium of Li+, K+, Na+, Mg2+//Cl-, SO42- -H2O system at low temperature, meta-stable phase equilibrium at changing temperatures and non-equilibrium salt-forming principle will be investigated in this work. This project involves: 1) The phase equilibrium of Li, K+, Na+, Mg2+//Cl-, SO42- -H2O system saturated with NaCl at -15℃；2) non-equilibrium salt-forming principle, meta-stable phase equilibrium at varying temperatures of key salts in this system and the relationship between the sides; 3) Study the relationship between interaction parameters and temperature; building the thermodynamic mathematical model for the calculation of phase equilibrium at low temperature. By these works above, the key science problems: what is the effect of temperature on crystallization capacities of single or double salts and non-equilibrium salt-forming, what is relationship between the non-equilibrium salt-forming and meta-stable phase equilibrium, can be identified. These works can provide theoretical guidance for industrial process to form salt optionally and directionally, and to weaken or eliminate the effect of magnesium on the separation of potassium and lithium from brine, and to optimize technology.