The extraction of rare earth elements (REE) has experienced a significant transition from primary sources to secondary and tertiary (alternative) sources. Ion-adsorbed clay (IAC) deposits have attracted considerable attention due to their abundant presence of sought-after elements. Nonetheless, the recovery of rare earth elements faces several challenges. In-situ recovery or leaching is regarded as the most environmentally friendly method and a prospective alternative to conventional soil excavation, shaft, and open-pit mining activities. However, this technique can induce clay swelling, which subsequently diminishes permeability to flow. The injection of a leaching solution, primarily composed of water, destabilizes the clay interlayers, contributing to this phenomenon. A common solution is the use of inhibitors such as magnesium and ammonium salts. Nonetheless, their usage threatens the environment's sustainability and is costly for large-scale utilization, requiring other options. Deep eutectic solvents (DES) have recently gained popularity due to their great tunability, low cost, and environmental friendliness. As such, researchers have argued that it has demonstrated some positive qualities such as more practical preparation methods, higher purity, lower cost, less corrosive, and biodegradability, specifically in the extraction and separation of metals. Therefore, this review analyses the up-to-date mechanics of REE extraction, state-of-the-art appraisal of leaching in ion adsorbed clays, timely assessment of clay swelling with conventional inhibitors, and progressively study DES as alternative solvents for rare earth element recovery and clay swelling inhibitors in ion adsorbed clay deposits. Additionally, this review presents conductor-like screening model for real solvents (COSMO-RS) as a suitable tool to screen potential DES to minimize swelling. A future study is proposed to investigate the interaction between DES, IACs, and REEs at the molecular and nanoscale levels through molecular simulations to ensure optimal recovery efficiency. Predictive algorithms such as COSMO-RS can be utilized to evaluate, modify, and design more environmentally friendly DES. The synthesized DES can then be used to extract REEs from IACs. Additionally, besides screening, COSMO-RS can be employed to analyze the thermodynamics and interactions between REEs and DES.

中文翻译：

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离子吸附稀土粘土：膨胀挑战和未来解决方案


稀土元素 (REE) 的提取经历了从初级来源到二级和三级（替代）来源的重大转变。离子吸附粘土（IAC）矿床由于富含所需元素而引起了广泛关注。然而，稀土元素的回收面临着一些挑战。原位恢复或浸出被认为是最环保的方法，也是传统土壤挖掘、竖井和露天采矿活动的潜在替代方法。然而，这种技术会引起粘土膨胀，从而降低流动的渗透性。注入主要由水组成的浸出溶液会破坏粘土夹层的稳定性，从而导致这种现象。常见的解决方案是使用镁盐和铵盐等抑制剂。尽管如此，它们的使用威胁到环境的可持续性，并且大规模使用成本高昂，需要其他选择。低共熔溶剂（DES）由于其良好的可调性、低成本和环境友好性而最近受到欢迎。因此，研究人员认为，它表现出了一些积极的品质，例如更实用的制备方法、更高的纯度、更低的成本、更少的腐蚀性和可生物降解性，特别是在金属的提取和分离方面。因此，本综述分析了稀土元素提取的最新机理、离子吸附粘土浸出的最新评估、传统抑制剂对粘土膨胀的及时评估，并逐步研究 DES 作为稀土的替代溶剂离子吸附粘土矿床中的元素回收和粘土膨胀抑制剂。 此外，本综述提出了真实溶剂的类导体筛选模型 (COSMO-RS)，作为筛选潜在 DES 以最大限度减少膨胀的合适工具。未来的研究计划通过分子模拟研究 DES、IAC 和 REE 在分子和纳米级水平上的相互作用，以确保最佳的回收效率。 COSMO-RS 等预测算法可用于评估、修改和设计更环保的 DES。合成的 DES 可用于从 IAC 中提取 REE。此外，除了筛选之外，COSMO-RS 还可用于分析 REE 和 DES 之间的热力学和相互作用。