Das Prasanjit, Behera Binapani, Sanjay Kali, Devi Niharbala
Department of Chemistry, Institute of Technical Education and Research, Siksha 'O' Anusandhan Deemed to Be University Bhubaneswar-751030 Odisha India
Department of Hydro and Electrometallurgy, CSIR-Institute of Minerals and Materials Technology Bhubaneswar-751013 Odisha India
RSC Adv. 2025 Jan 13;15(2):912-923. doi: 10.1039/d4ra08474h. eCollection 2025 Jan 9.
The widespread use of neodymium-iron-boron (NdFeB) magnets has raised concerns about the environmental impact of their disposal, prompting the need for sustainable recycling strategies. Traditional solvents used in recycling are toxic and flammable, making them risky to use. Ionic liquids are safer and greener options with low vapor pressure, high stability, and less flammability. This study introduces an eco-friendly recycling approach utilizing the [P66614][Cy272] ionic liquid to selectively extract iron and recover rare earth elements (REEs) from the leach liquor of waste NdFeB magnets. Pre-treatment processes enhanced metal concentration before leaching, including demagnetization, grinding, and screening. Optimal leaching conditions: 2 mol L HCl, 80 °C, 10 g L pulp density, and 90 minutes, resulted in complete leaching of REEs (Dy, Pr, Nd), iron, and boron. Using 0.01 mol L [P66614][Cy272] ionic liquid, 100% of the iron was removed from the leach liquor with minimal co-extraction of REEs (∼4%). Precipitation of iron leading to FeO (hematite) after calcination and is verified through XRD and SEM-EDS analyses. The ionic liquid also enabled 81.1% recovery of HCl from the leach liquor, reducing neutralization needs and operational costs. Subsequent REEs separation using 0.01 mol L [P66614][Cy272] ionic liquid demonstrated high selectivity, achieving separation factors of 18.55 (Dy/Pr) and 15.52 (Dy/Nd) at pH 2.03. Dy(iii) was successfully separated from NdFeB leach solutions using counter-current extraction, leaving 6.0 mg L in the raffinate, requiring two extraction stages at a 2 : 3 organic-to-aqueous phase (O/A) ratio. The reusability of the ionic liquid further enabled a sustainable, closed-loop recycling process. This approach highlights the potential for integrating ionic liquids into green technologies for NdFeB magnet recycling, ensuring resource recovery while minimizing environmental impact.
钕铁硼（NdFeB）磁体的广泛使用引发了人们对其处置对环境影响的担忧，这促使人们需要可持续的回收策略。传统回收中使用的溶剂有毒且易燃，使用起来存在风险。离子液体是更安全、更环保的选择，具有低蒸气压、高稳定性和较低的可燃性。本研究引入了一种利用[P66614][Cy272]离子液体的环保回收方法，以选择性地从废弃NdFeB磁体的浸出液中提取铁并回收稀土元素（REEs）。预处理过程在浸出前提高了金属浓度，包括退磁、研磨和筛选。最佳浸出条件为：2 mol/L盐酸、80°C、10 g/L矿浆密度和90分钟，可使稀土元素（镝、镨、钕）、铁和硼完全浸出。使用0.01 mol/L [P66614][Cy272]离子液体，可从浸出液中去除100%的铁，同时稀土元素的共萃取量最小（约4%）。铁沉淀后经煅烧生成FeO（赤铁矿），并通过XRD和SEM-EDS分析得到验证。离子液体还能从浸出液中回收81.1%的盐酸，减少了中和需求和运营成本。随后使用0.01 mol/L [P66614][Cy272]离子液体进行稀土元素分离，显示出高选择性，在pH 2.03时实现了18.55（镝/镨）和15.52（镝/钕）的分离因子。通过逆流萃取成功地从NdFeB浸出溶液中分离出镝（iii），萃余液中残留6.0 mg/L，在有机相/水相（O/A）比为2∶3的情况下需要两个萃取阶段。离子液体的可重复使用性进一步实现了可持续的闭环回收过程。这种方法突出了将离子液体集成到NdFeB磁体回收绿色技术中的潜力，确保资源回收的同时将环境影响降至最低。
