Neodymium recovery from permanent magnets: A breakthrough approach using Deep Eutectic Solvents and Mica

Abstract

The NdFeB permanent magnets, that contain Neodymium (Nd) are invariably required for the renewable energy industries. Conventional solvent extraction-based procedures for extracting neodymium from these magnets have considerable drawbacks, including high energy consumption, the usage of chemicals, and the production of secondary organic waste. This study presents an innovative approach to address these challenges. To our knowledge, this study is the first to utilise the combination of salicylic acid and choline chloride (SA-ChCl) to make deep eutectic solvents (DESs) for leaching neodymium from discarded neodymium-ferrite magnets and mica for recovery process. Several analyses were performed to verify the efficacy of this strategy. The successful synthesis of DESs was confirmed by FTIR measurement, and Nd adsorption on the adsorbent was shown to be remarkable. Aliphatic hydrocarbons were detected in the DESs by NMR spectroscopy, and the adsorbent's crystalline structure and surface shape were shown, respectively, by XRD patterns and SEM micrographs. It was discovered that variables including the solid/liquid mass ratio, leaching period, and temperature had an impact on both the leaching efficiency and the separation factor. The ideal parameters were discovered to be 1.2 g/L, 200 rpm, and 60 °C, respectively, during the study's investigation into the effects of mica dose, stirring rate, and temperature on mica adsorption. With a maximum leaching effectiveness of 97 %, this technique offers hope for DESs reuse. The maximum desorption efficiency was also demonstrated by calcium chloride, allowing for efficient recycling of the mica adsorbent. Interestingly, a model of an artificial neural network (ANN) with 10 neurons and one hidden layer was created to predict the greatest Nd recovery, validating the efficiency of the DESs-Mica technique in boosting Neodymium recovery from discarded permanent magnets.