Recovery of Rare Earths from End-of-Life NdFeB Permanent Magnets from Wind Turbines

Abstract

This work aims to recover rare earths from wind turbines NdFeB magnets through pyrometallurgical and hydrometallurgical techniques. First, a NdFeB hydride powder is obtained by decrepitation with hydrogen. Subsequently, this powder was subjected to a chlorination roasting process and successive leaching with water to bring the metals into solution. This was followed by a liquid-liquid extraction to remove the iron and purify the rare earth solution. For this purpose, Aliquat 336 diluted in Solvesso was selected as the iron selective extraction agent. As a single extraction was not enough for complete iron removal, a second Fe extraction step was carried out. This second extraction step was performed using the restored organic phase. This restoration was achieved by treating the organic phase with Na₂SO₃ and then washing it with a 3 M HCl solution. In this way, the process was achieved more sustainably. Finally, the rare earths contained in the final solution were precipitated using oxalic acid to obtain mixed rare earth oxalates.