Li+,Na+,Ca2+,Sr2+//Cl-,B4O72--H2O体系288.15K介稳相平衡研究

Nanyishan oilfield brine in the Qaidam Basin are famous for their large reserves and high contents of lithium, calcium, strontium and borate resources. The exploitation value is higher than the salt lakes of Atacama in Chile. Phase equillibria and phase diagram is the important theoretic basis for the separation and extraction of salt minerals. This study simulates the nature evaporation conditions of Nanyishan area, and the aqueous system Li+, Na+, Ca2+, Sr2+//Cl-, B4O72-–H2O and its subsystems at 288.15K not reported so far are determined with the isothermal evaporation method. The metastable solubilities and the physicochemical properties (density, viscosity, refractive index, conductivity and pH value) for the hexaternary system and its subsystems at 288.15K are measured. On the basis of Pitzer ion-interaction for a mixed aqueous electrolytic solution, the Pitzer single-salt parameters and the mixing ion-interaction parameters containing lithium, calcium, strontium and borate in the system were fitted. The prediction of the solubilities for the hexaternary system and its subsystems are established. Analysing the metastable phase diagrams of the systems to reveal the rule of transfer, concentration and salt-out of minerals, establish the project for the separation and extraction of salt minerals, which all provides a theoretical foundation and scientific basis for the highly efficient exploitation of this precious oilfield brine resources.

柴达木盆地南翼山油田卤水是富含锂、钙、锶、硼的大型综合性盐类矿床，储量大，品位高，开采价值远在智利阿塔卡玛盐湖之上。卤水相平衡与相图是盐类矿物分离提取的重要理论基础，本项目模拟该油田水区自然蒸发条件，采用等温蒸发法开展未见报道的Li+,Na+,Ca2+,Sr2+//Cl-,B4O72--H2O体系及子体系288.15K的介稳相平衡与相图研究，实验测定介稳平衡溶液中各组分浓度和液相物理化学性质（密度、粘度、折光率、电导率和pH值）；应用Pitzer电解质溶液模型，拟合所需含锂硼锶钙的Pitzer单盐参数、混合离子作用参数，理论预测该六元体系及子体系的介稳溶解度。对该体系介稳相图进行工艺解析，掌握卤水蒸发过程中锂、钙、锶、硼的迁移、富集及析盐规律，制定盐类分离提取工艺方案，为该油田卤水的高值开发提供理论基础和科学依据。

针对柴达木盆地南翼山富含锂、钾、锶、钙、硼油田卤水液体矿产资源开发利用，本项目模拟该油田水区自然蒸发条件，采用等温蒸发法完成六元体系Li+,Na+,Ca2+,Sr2+//Cl-,borate-H2O及其五元、四元、三元子体系 288.15 K 介稳相平衡与相图研究， 获得上述卤水体系介稳溶解度数据和液相密度、折光率、物化性质。确定了相关四元、五元、六元子体系的介稳相图和物化性质组成图。同时发展了Pitzer电解质溶液理论模型，拟合得到配套的Pitzer单盐参数、混合离子作用参数和平衡固相的溶解度积，理论计算该六元体系Li+,Na+,Ca2+,Sr2+//Cl-,borate-H2O及子体系的介稳溶解度，理论计算值与实验值吻合得很好。研究成果不仅丰富了化工热力学基础数据，同时可指导南翼山油田卤水资源综合开发利用。发表学术论文11篇，国家发明专利4项，培养已毕业博士1名，硕士研究生2名。