高镁锂比盐湖老卤中锂镁资源综合利用应用基础研究

There are abundant brine resources with high Mg/Li ratio in the Qaidam Basin, but their exploitation still can't meet the requirement of market for the great difficulties of lithium and magnesium separation. In order to realize the separation of lithium and magnesium as well as high-value utilization of magnesium in high Mg/Li ratio brine, this proposed project innovatively presents the scheme of extraction-electrodeposition magnesium to separate lithium and magnesium so as to solve the bottleneck problems of high acidity, easy to emulsify and difficulty to recycle FeCl3 during lithium extraction, and high energy consumption, low added-value during magnesium utilization. On the basis of theory and innovation methods of solution chemistry, phase chemistry, electrochemistry and thermodynamics, this project will carry out the applied basic researches on the comprehensive utilization of lithium and magnesium using BT2.15 microcalorimeter, ICP-OES, SEM-EDS as main tools, where the extracting magnesium from the mother liquor is the breakthrough and the high-value utilization of magnesium by electrodeposition in the non-aqueous media is the research emphasis. The purpose of this project is to reveal the extraction phase equilibrium, extraction thermodynamics and mechanisms during magnesium extraction, and the electrodeposition mechanisms, thermodynamic characteristics and interference behaviors during magnesium electrodeposition so as to obtain the technical parameters on the separation of lithium and magnesium as well as high-value utilization of magnesium, by which this research would provide technical support and theoretical basis for the reasonably development and utilization of lithium and magnesium resources in salt lakes.

我国柴达木盆地高镁锂比卤水资源丰富，但卤水中锂镁分离难度大，致使我国富含锂镁的盐湖卤水中锂镁资源开发远不能满足市场的需要。本项目结合柴达木盆地盐湖卤水资源特征，以高镁锂比卤水中锂镁分离及镁资源高值化利用为目标，针对萃取锂分离锂镁的酸度高、易乳化、FeCl3难回收和镁资源利用过程中能耗高、附加值低等瓶颈问题，创新性地提出萃取—电沉积法提取镁分离锂镁的技术方案，开展高镁锂比卤水中锂镁综合利用的前沿技术应用基础研究。采用BT2.15微量热仪、ICP-OES、SEM-EDS为主要分析表征手段，以萃取镁分离锂镁为突破口，以非水介质电沉积镁为研究重点，综合溶液化学、相化学、电化学和热动力学理论和创新研究方法，揭示镁萃取过程中的萃取相平衡、萃取热动力学，以及镁电沉积过程中的电沉积行为、动力学特征和干扰机制，获取锂镁分离及镁高值化利用技术参数，为高镁锂比卤水中锂镁资源的有效利用提供理论基础和技术支撑。

针对柴达木盆地高镁锂比盐湖卤水中锂镁资源的综合利用，本项目在提出“萃取—电沉积”创新技术路线基础上，开展了锂镁分离及镁资源高值化利用应用基础研究。首先，针对高盐卤水中低浓度锂的准确测定问题，通过改进传统的基体匹配法，成功建立了低干扰的卤水中锂的ICP-OES准确测定方法。在此基础上，开发了几种新型锂萃取体系及萃取方法。特别是以80%TIBP+20%SK萃取体系结合离心萃取的提锂创新技术，不仅实现了锂的高效分离提取，还成功解决了FeCl3的回收利用问题。其次，为实现萃取镁分离锂镁与有机相直接电沉积镁技术的结合，成功开发了一种基于离子液体的新型萃镁体系，不仅获得了镁的萃取分离，还获得了较高的有机体系电导率。在此基础上，通过对富镁有机相中镁电沉积条件及电极体系的详细研究，成功实现了镁的直接电沉积，为高镁锂比卤水中镁的高值化利用奠定了基础。项目运行期间，参加国际和国内学术会议各2次，提交会议交流Poster 9项、交流会议论文18篇，并作为主办方成功举办“盐湖与盐业国际学术交流会”。目前，已发表SCI论文19篇（第一标注11篇）；申请发明专利5项，其中已授权3项；培养研究生5名。超额完成了本项目任务。