温控型酸性离子液体浸出-分离氟碳铈矿中氟和稀土元素的机理研究

Bastnaesite is the most important light rare earth ore. Developing the efficient separation and recovery technology of fluorine and rare earths from bastnaesite is of great importance to promote the development of rare earth industry. Aimed at the adverse effect of fluorine on leaching rare earth and the pollution problem of fluorine in metallurgical process of bastnaesite, the temperature controlled acidic ionic liquid ([Hbet][Tf2N]) was employed to leach bastnaesite. The phase equilibrium of this ionic liquid and water depends on the temperature, which can be utilized to achieve the aim of synchronous leaching and separation of fluorine and rare earth elements during the heating and cooling of the leaching system. The research contents mainly include: (1) the phase equilibrium mechanism of ionic liquid-water and the behaviors of their miscibility and phase separation, optimizing the physical parameters of ionic liquid leaching system; (2) studying the leaching reaction behavior of bastnaesite by ionic liquid, and revealing the bonding mechanism between rare earth elements and ionic liquid and the phase separation and equilibrium mechanism between the ionic liquid loaded with rare earth and the aqueous solution containing fluorine; (3) the stripping rare earth mechanisms of loaded ionic liquid. The successful implementation of this project will further expand the separation system of fluorine and rare earth elements, which will provide the theoretical guidance for the development of cleaning process of bastnaesite leached by ionic liquid.

氟碳铈矿是最重要的轻稀土矿，开发氟碳铈矿中稀土、氟的高效分离与回收技术对促进稀土行业绿色发展至关重要。针对氟碳铈矿冶炼过程中氟对稀土提取的不利影响及氟污染问题，本课题开展温控型酸性离子液体（[Hbet][Tf2N]）浸出-分离氟碳铈矿中氟和稀土的研究，利用[Hbet][Tf2N]与水两相平衡受温度控制的特性，实现氟和稀土加热浸出-降温分离的同步提取。研究内容主要包括：1、[Hbet][Tf2N]-H2O体系混溶和分离的两相平衡机制，优化离子液体浸出体系物性参数；2、离子液体对氟碳铈矿的浸出行为，揭示稀土元素与离子液体的作用机理以及负载稀土的离子液体与含氟水溶液的相分离平衡机制；3、负载离子液体中稀土的反萃机理。本项目的顺利实施将进一步扩展氟碳铈矿冶炼过程中氟、稀土的分离体系，为开发离子液体处理氟碳铈矿的清洁工艺提供理论指导。

氟碳铈矿是最重要的轻稀土矿，开发氟碳铈矿绿色冶炼技术的核心是如何解决稀土与氟离子的选择性配位，避免氟离子对稀土提取的不利影响。功能化离子液体为稀土阳离子与氟阴离子的分离提供了一种新的途径。利用温控型酸性离子液体（[Hbet][Tf2N]）羧基溶解稀土化合物并与稀土阳离子配位络合作用，提出了[Hbet][Tf2N]浸出-分离氟碳铈矿中稀土与氟的研究。研究内容主要包括：1、研究[Hbet][Tf2N]-H2O体系混溶和分离的两相平衡机制，优化离子液体浸出体系物性参数；2、研究离子液体对氟碳铈矿的浸出行为，揭示了稀土元素与离子液体的作用机理以及负载稀土的离子液体与含氟水溶液的相分离平衡机制；3、负载离子液体中稀土的反萃机理，及再生离子液体循环浸出性能。最终，通过氟碳铈矿碱分解预处理，利用[Hbet][Tf2N]-H2O体系混溶和分离特性，稀土浸出率达到90%以上，氟浸出率基本为零；冷却后，稀土离子被萃取进入离子液体相，与含少量氟离子的水溶液分离；采用盐酸、草酸溶液均能实现稀土离子的反萃回收及离子液体的再生，稀土反萃率达95%以上，再生离子液体循环4次时，仍具有90%以上的稀土浸出性能；其中草酸溶液比盐酸溶液具有更好的离子液体再生效果。本项目研究结果不仅为氟碳铈矿短流程绿色提取提供了一种新的技术原型，也为功能化离子液体在有色金属清洁冶金中的拓展应用提供了技术参考。项目在研期间，以第一或通讯作者发表SCI收录论文7篇；申请国家发明专利8项，其中授权6项，协助指导硕士研究生3名。