Recovery of neodymium and dysprosium from NdFeB magnet swarf

Abstract

The rare earth elements neodymium and dysprosium were separated and recovered from NdFeB permanent magnet swarf by hydrometallurgical route. The magnet swarf was leached with HCl after crushing and grinding, and from the leach liquor, Nd and Dy were separated by solvent extraction using NaCyanex 302. The separation factor (β) of Dy/Nd with NaCyanex 302 was high at low equilibrium pH. So Dy was first separated from the leach liquor at pH0.5 (equilibrium pH1.2). After separation of Dy, the separation of Nd was also carried out with the same extractant. The effect of equilibrium pH and extractant concentration on the extraction of Nd and Dy with NaCyanex 302 was studied. The McCabe-Thiele plots for extraction of both Dy and Nd with NaCyanex 302 were constructed and the number of stages for quantitative extraction was determined. The stripping of loaded organic was carried out with three different mineral acids and it was observed that the stripping efficiency followed the order HCl<HNO3<H2SO4. The McCabe-Thiele plots for stripping of loaded organic were also constructed. The reaction mechanism of both Nd and Dy was determined from the slope analysis method and the extracted species was found to be MA3.5HA.