ABSTRACT Waste electrical and electronic equipments (WEEE or e-waste) are an important source for rare earth elements (REEs). Among various type of WEEE, NdFeB magnets are known for their high content of neodymium (Nd) and dysprosium (Dy). Recovery of REEs from NdFeB magnets is of prime interest for the industry to meet the ever-growing demand for REEs. In this study, some physical and hydrometallurgical approaches including demagnetization, grinding, screening, leaching, precipitation and extraction have been adopted to study the Nd and Dy recovery from spent NdFeB magnets. Various inorganic (HCl, HNO₃, H₂SO₄ and aqua regia) and organic reagents (acetic acid and oxalic acid) were tested as lixiviants for leaching of the magnets. As a new approach, the recovery of Nd and Dy in the leaching solution was tested by eliminating the iron by a solution purification process involving precipitation of ferric iron in solution as hydroxide and solvent extraction with ionic liquids (ILs). The comparative studies demonstrated that the extraction efficiency of di-2-ethylhexyl phosphoric acid (D2EHPA) was higher than trihexyltetradecylphosphonium chloride (CYPHOS® IL101) after leaching stage. Nd and Dy were successfully extracted with complete recovery from the optimized system.

中文翻译：

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从废硬盘驱动器 (HDD) 中回收钕 (Nd) 和镝 (Dy) 的多阶段工艺

摘要 废弃电子电气设备（WEEE 或电子垃圾）是稀土元素 (REE) 的重要来源。在各种类型的 WEEE 中，钕铁硼磁铁以其高含量的钕 (Nd) 和镝 (Dy) 而闻名。从 NdFeB 磁体中回收 REE 是该行业满足对 REE 不断增长的需求的主要兴趣。在这项研究中，一些物理和湿法冶金方法包括退磁、研磨、筛选、浸出、沉淀和提取，已被用于研究从废 NdFeB 磁体中回收 Nd 和 Dy。测试了各种无机物（HCl、HNO 3 、H 2 SO 4 和王水）和有机试剂（乙酸和草酸）作为浸出磁体的助滤剂。作为一种新方法，浸出液中 Nd 和 Dy 的回收率是通过溶液纯化过程去除铁来测试的，该过程包括将溶液中的三价铁沉淀为氢氧化物和用离子液体 (IL) 进行溶剂萃取。对比研究表明，在浸出阶段后，二-2-乙基己基磷酸 (D2EHPA) 的提取效率高于三己基十四烷基氯化鏻 (CYPHOS® IL101)。Nd 和 Dy 被成功提取，并从优化的系统中完全回收。对比研究表明，在浸出阶段后，二-2-乙基己基磷酸 (D2EHPA) 的提取效率高于三己基十四烷基氯化鏻 (CYPHOS® IL101)。Nd 和 Dy 被成功提取，并从优化的系统中完全回收。对比研究表明，在浸出阶段后，二-2-乙基己基磷酸 (D2EHPA) 的提取效率高于三己基十四烷基氯化鏻 (CYPHOS® IL101)。Nd 和 Dy 被成功提取，并从优化的系统中完全回收。