多重化学平衡调控离子吸附型稀土与铝铀钍的浸取及其综合回收

离子吸附型稀土是我国最早发现的一类特殊的稀土资源。但对稀土离子的交换浸出机理认识仍然不足，共存铀钍钪等资源也未回收。由于粘土矿物表面的离子吸附-解吸行为受浸取溶液中阴阳离子类型、浓度和酸度的影响非常复杂，目前还缺乏有效的能够调控各种离子高效和选择性浸出的理论依据。为提高资源开发利用效率，消除环境影响，本项目拟对比研究硫酸盐电解质中加入络合剂和控制酸碱性对离子吸附型粘土表面稀土及共存离子的吸附-解吸行为的影响；并从配位、沉淀平衡和酸效应与各种离子吸附-解吸平衡的耦合关系来调控离子的存在形式和含量分布，实现稀土及共存离子的高效和选择性浸取或稳定。重点研究稀土、铝、铀、钍等离子在单一或多重化学平衡控制下的吸附-解吸行为和机理，揭示调控目标离子吸附和解吸效率的方法原理，并用于稀土和铀离子的高效浸取和铝钍离子的稳定吸附；结合萃取分离体系和分离流程的优化，实现有价元素的综合回收利用。

Ion adsorption rare earths is a special rare earth resource which was first found in China and has realized industrial exploitation. However, the understanding for the mechanism of rare earth ion exchange leaching is still insufficient, and the co-existing uranium, thorium scandium and other resources have not been recovered. Because the ion adsorption-desorption behavior on the surface of clay minerals is affected by the type of anion and cation, the concentration and acidity of the leaching solution, there is no effective theoretical basis for controlling the efficient and selective leaching of all kinds of ions. In order to improve the efficiency of exploitation and utilization of resources and eliminate the environmental impact, the effects of sulfate electrolytes with or without adding complexing agent and controlling acid-base on the adsorption-desorption properties of rare earth and co-existing ions on the surface of ion-adsorbed clay were comparatively studied in this project. The coupling relationship of coordination, precipitation equilibrium and acid effect with the adsorption-desorption equilibrium of various ions is used to regulate the existing form and content distribution of ions, so as to achieve efficient and selective leaching of rare earth or stabilization of co-existing ions. The present studies are focused on the adsorption-desorption behavior and mechanism of rare earth, aluminum, uranium and thorium controlled under single or multiple chemical equilibrium, and the principle of regulating the adsorption and desorption efficiency of target ions is revealed, which can be used for efficient leaching of rare earth and uranium ions and stable adsorption of aluminum and thorium ions. Combined with the optimization of extraction separation system and separation process, the comprehensive recovery and utilization of valuable elements can be realized.