Enhanced Separation of Neodymium and Dysprosium by Nonaqueous Solvent Extraction from a Polyethylene Glycol 200 Phase Using the Neutral Extractant Cyanex 923ACS Sustainable Chemistry & Engineering ( IF7.632 ) Pub Date : 2020-12-14, DOI: 10.1021/acssuschemeng.0c07207Brecht Dewulf; Nagaphani Kumar Batchu; Koen Binnemans
Neodymium and dysprosium can be efficiently separated by solvent extraction, using the neutral extractant Cyanex 923, if the conventional aqueous feed phase is largely replaced by the green polar organic solvent polyethylene glycol 200 (PEG 200). While pure aqueous and pure PEG 200 solutions in the presence of LiCl or HCl were not able to separate the two rare earth elements, high separation factors were observed when extraction was performed from PEG 200 chloride solutions with addition of small amounts of water. This addition of water bridges the gap between traditional hydrometallurgy and novel solvometallurgy and overcomes the challenges faced in both methods. The effect of different variables was investigated: water content, chloride concentration, type of chloride salt, Cyanex 923 concentration, scrubbing agent. A Job plot revealed the extraction stoichiometry is DyCl3·4L, where L is Cyanex 923. The McCabe-Thiele diagram for dysprosium extraction showed that complete extraction of this metal can be achieved by a 3-stage counter-current solvent extraction process, leaving neodymium behind in the raffinate. Finally, a conceptual flow sheet for the separation of neodymium and dysprosium including extraction, scrubbing, stripping, and regeneration steps was presented. The nonaqueous solvent extraction process presented in this paper can contribute to efficient recycling of rare earths from end-of-life neodymium-iron-boron (NdFeB) magnets.中文翻譯：
通過使用中性萃取劑Cyanex 923從聚乙二醇200相中非水溶劑萃取來增強釹和Dy的分離如果常規的水性進料相在很大程度上被綠色極性有機溶劑聚乙二醇200（PEG 200）取代，則可以使用中性萃取劑Cyanex 923通過溶劑萃取有效地分離釹和。儘管在LiCl或HCl存在下的純水溶液和純PEG 200溶液無法分離這兩種稀土元素，但是從PEG 200氯化物溶液中加入少量水進行萃取時，觀察到了很高的分離係數。這種水的添加彌合了傳統溼法冶金和新型溶劑冶金之間的差距，並克服了兩種方法所面臨的挑戰。研究了不同變量的影響：水含量，氯化物濃度，氯化物鹽的類型，Cyanex 923濃度，洗滌劑。3 ·4L，其中L為Cyanex923。The萃取的McCabe-Thiele圖顯示，可以通過3級逆流溶劑萃取工藝完全萃取該金屬，而在萃餘液中留下釹。最後，提出了用於分離釹和的概念流程圖，包括萃取，洗滌，汽提和再生步驟。本文提出的非水溶劑萃取工藝可以幫助從報廢的釹鐵硼（NdFeB）磁體中有效回收稀土。