南翼山富锂钾锶溴油田卤水体系多温稳定相平衡与热力学性质研究

Phase equilibrium and chemistry model are important theoretical foundations for the exploitation of brine resources. Investigation of the thermodynamic properties provides basic data to construct the complex chemistry model of the brine system. The mother liquor of oilfield brine after boron separating in Nanyishan district of Qaidamu basin is characterized with high concentrations of lithium, potassium, strontium, and bromine. In this project, the stable phase equilibria and thermodynamic properties of the seven-component system Li+,Na+,K+,Ca2+,Sr2+//Cl-,Br-−H2O at multi-temperatures (273.15, 323.15 and 373.15 K) using the isothermal dissolution and isopiestic method. The Pitzer parameters of the seven-component system will be fitted with the thermodynamic properties of the binary and ternary systems measured with the isopiestic method and validated with the thermodynamic properties of artificial brine. Combing the equilibrium criterion, the Pitzer chemical model at multi-temperatures (273.15~373.15 K) will be constructed. Then, the solubilities and thermodynamic properties of the seven-component system will be predicted. This study will be valuable to indicate compositional variations of the brine, processes and mechanisms of the transitions between mineral crystallization and dissolution. The obtained multi-phase diagram and the temperature gradient effects will provide the fundamental chemical engineering thermodynamic data for the finer separation and comprehensive exploitation of brine resources.

卤水体系相平衡与化学模型是卤水资源开发利用的重要理论基础，卤水体系热力学性质研究为化学模型的构建提供基础数据。本项目针对南翼山提硼后的油田老卤富含锂、钾、锶、溴等特点，拟采用等温溶解法和等压法，开展具有老卤组成特征的七元体系Li+,Na+,K+,Ca2+,Sr2+//Cl-,Br-−H2O多温（273.15、323.15和373.15 K）稳定相平衡和热力学性质实验研究；根据等压法测定的二元和三元热力学性质实验结果拟合必需的Pitzer模型参数，并采用复杂合成卤水体系热力学性质验证，结合固液平衡判据，构建该体系多温（273.15~373.15 K）Pitzer化学模型，进而理论预测上述复杂体系溶解度和热力学性质。本项目研究结果将有助于揭示油田老卤组成变化、盐类矿物结晶和溶解转化的过程和机制，结合实验与理论多温相图和温差效应，为老卤的精细化分离及其综合利用提供重要的化工热力学基础数据。

本项目针对南翼山提硼后的油田老卤富含锂、钾、锶、溴等特点，采用等温溶解法和等压法，开展了具有老卤组成特征的卤水体系多温稳定相平衡和热力学性质实验研究，并构建了相应体系的Pitzer热力学模型，获得的研究成果如下：（1）完成了七元体系Li+,Na+,K+,Ca2+,Sr2+//Cl-,Br-−H2O及其子体系的多温相平衡实验研究，获得了锂钾锶溴水盐体系的溶解度数据和液相物化性质，绘制了相应体系的相图和物化性质组成图，该体系低温时形成锂钙复盐、钙锶固溶体和氯溴固溶体；高温时形成钾钙复盐和氯溴固溶体；（2）完成了多个三元体系等压法实验研究，补充了缺乏的热力学数据，根据实验结果拟合了缺乏的Pitzer模型参数；（3）结合文献溶解度和热力学数据拟合了必需的Pitzer模型参数，采用固液平衡判据，构建了上述体系溶解度理论计算的Pitzer热力学模型，并理论计算了相应体系溶解度；（4）根据卤水体系相图和Pitzer模型研究结果，探讨了卤水分离的工艺路线。本项目研究结果揭示了油田老卤组成变化、盐类矿物结晶和溶解转化的过程和机制，为老卤的精细化分离及其综合利用提供了重要的化工热力学基础数据。已发表期刊论文20篇（SCI论文15篇，中文期刊论文5篇），会议论文12篇，联合培养研究生5名。超额完成了本项目任务。