Recovery of Neodymium from Waste Permanent Magnets by Hydrometallurgy Using Hollow Fibre Supported Liquid Membranes

• Published in: Solvent Extraction Research and Development, Japan Vol. 27; no. 2; pp. 69 - 80
• Main Authors: NI’AM, Achmad Chusnun, LIU, Yi-Hsien, WANG, Ya-Fen, CHEN, Shyh-Wei, CHANG, Gen-Mu, YOU, Sheng-Jie
• Format: Journal Article
• Language: English
• Published: Japan Association of Solvent Extraction 2020
• ISSN: 1341-7215; 2188-4765
• DOI: 10.15261/serdj.27.69

The recycling of the rare earth neodymium (Nd) is vital to providing greener technology for many industries. In this paper its recovery from waste permanent magnets (WPMs) is explored using a hydrometallurgical process involving separation using hollow fiber supported liquid membranes (HFSLMs). After demagnetization, the options for WPMs leaching were investigated by varying mineral acids, acid concentrations and solid/liquid (S/L) ratios. The separation Nd from iron (Fe) was carried out by precipitation using oxalic acid. Nd in WPMs was recovered by solvent extraction using D2EHPA in Isopar-L. The influence of various parameters such as pH and organic/aqueous (O/A) phase ratio were investigated. Optimum leaching was achieved using 3 M H2SO4 with an S/L ratio of 1 g/50 mL to obtain 485 g/kg of Nd. Nd-separation from Fe was successfully performed using 0.6 M D2EHPA with an O/A phase ratio of 3 at a pH of 1.26 – 2.0 resulting in Nd-recovery of 97.48%. The optimum stripping was achieved using 6 M HNO3. In the HFSLM experiments, the concentration of Nd in the aqueous strip solution was 4120 mg/L whilst that in the aqueous feed solutions was 658 mg/L. The HFSLM module used recovered 90.82% of the Nd within 35 min.