Kitagawa Jiro, Uemura Ryohei
Department of Electrical Engineering, Faculty of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashi-ku, Fukuoka, 811-0295, Japan.
Sci Rep. 2017 Aug 14;7(1):8039. doi: 10.1038/s41598-017-08629-z.
There is considerable interest in extraction of rare earth elements from NdFeB magnets to enable recycling of these elements. In practical extraction methods using wet processes, the acid waste solution discharge is a problem that must be resolved to reduce the environmental impact of the process. Here, we present an encouraging demonstration of rare earth element extraction from a NdFeB magnet using a closed-loop hydrochloric acid (HCl)-based process. The extraction method is based on corrosion of the magnet in a pretreatment stage and a subsequent ionic liquid technique for Fe extraction from the HCl solution. The rare earth elements are then precipitated using oxalic acid. Triple extraction has been conducted and the recovery ratio of the rare earth elements from the solution is approximately 50% for each extraction process, as compared to almost 100% recovery when using a one-shot extraction process without the ionic liquid but with sufficient oxalic acid. Despite its reduced extraction efficiency, the proposed method with its small number of procedures at almost room temperature is still highly advantageous in terms of both cost and environmental friendliness. This study represents an initial step towards realization of a closed-loop acid process for recycling of rare earth elements.
从钕铁硼磁体中提取稀土元素以实现这些元素的回收利用受到了广泛关注。在使用湿法的实际提取方法中，酸性废液排放是一个必须解决的问题，以减少该过程对环境的影响。在此，我们展示了一种令人鼓舞的方法，即使用基于闭环盐酸（HCl）的工艺从钕铁硼磁体中提取稀土元素。该提取方法基于磁体在预处理阶段的腐蚀以及随后从HCl溶液中提取铁的离子液体技术。然后使用草酸沉淀稀土元素。已进行了三次提取，与使用无离子液体但有足够草酸的一次性提取过程时几乎100%的回收率相比，每次提取过程中溶液中稀土元素的回收率约为50%。尽管其提取效率有所降低，但所提出的方法在几乎室温下步骤较少，在成本和环境友好性方面仍然具有很大优势。这项研究代表了实现稀土元素回收闭环酸工艺的第一步。
