Recovery of Neodymium and Dysprosium from Waste Hard Disk Magnets: Roasting, Selective Leaching, Extraction and Stripping.

We demonstrate an end-to-end protocol for the recovery of Dy and Nd from used NdFeB magnets by following steps- crushing, roasting, grinding, leaching, liquid–liquid extraction and striping. The magnets were roasted over a temperature range of 923–1273 K. The influence of roasting temperature was studied by leaching the roasted samples with HCl solution. Roasting temperature, leaching temperature, leaching time, acid concentration, mixing speed, and pulp density were optimized to selectively leach Nd and Dy while most of the Fe was removed by the hydrolysis of Fe into Fe(OH)₃. Nd and Dy were extracted from the leach liquor using D2EHPA in a two-stage process. First, ~ 95% of Dy was extracted at a pH = 2, and 0.05 M D2EHPA and then Nd was extracted at pH = 4, A/O = 1 with 0.2 M D2EHPA in the second stage. Dy and Nd were completely recovered from the metal-rich organic phase by stripping with varied concentrations of HCl. [ABSTRACT FROM AUTHOR]