NdFeB permanent magnet scrap is regarded as an important secondary resource which contains rare earth elements (REEs) such as Nd, Pr and Dy. Recovering these valuable REEs from the NdFeB permanent magnet scrap not only increases economic potential, but it also helps to reduce problems relating to disposal and the environment. Hydrometallurgical routes are considered to be the primary choice for recovering the REEs because of higher REEs recovery and its application to all types of magnet compositions. In this paper, the authors firstly reviewed the chemical and physical properties of NdFeB permanent magnet scrap, and then carried out an in-depth discussion on a variety of hydrometallurgical processes for recovering REEs from the NdFeB permanent magnet scrap. The methods mainly included selective leaching or complete leaching processes followed by precipitation, solvent extraction or ionic liquids extraction processes. Particular attention is devoted to the specific technical challenge that emerges in the hydrometallurgical recovery of REEs from NdFeB permanent magnet scrap and to the corresponding potential measures for improving REEs recovery by promoting the processing efficiency. This summarized review will be useful for researchers who are developing processes for recovering REEs from NdFeB permanent magnet scrap.

Sodium salts were used in the reduction roasting and magnetic separation process to separate and recover iron and manganese from the high-iron manganese oxide ores to utilize the complex ores. Results showed that Na₂S₂O₃ was the most effective salt. A magnetic concentrate with 86.39 wt% TFe and 96.21 wt% Fe recovery as well as a nonmagnetic product with 54.84 wt% TMn and 85.96 wt% Mn recovery was obtained when the ore sample was reduced at 1100°C for 100 min in the presence of 7 wt% Na₂S₂O₃. In addition, the effects of roasting and separation parameters on the recovery of manganese and iron and the function mechanism of Na₂S₂O₃ were investigated.

In this study, a process of magnetizing roasting followed by magnetic separation, which is used to separate or recover tin and iron from the high calcium type tin- and iron-bearing tailings (containing 35.53 wt.% Fe and 0.56 wt.% Sn), was investigated . A magnetic concentrate containing 66.3 wt.% Fe and 0.07 wt.% Sn with an iron recovery rate of 92.9 wt.% was obtained under optimal conditions: anthracite ratio of 2.5:100, roasting temperature of 850°C, roasting time of 30 min, grinding time of 10 min, and magnetic field intensity of 0.1 T. In addition, the effect of roasting parameters on the separation of iron and tin and phase transformation of SnO₂ was investigated by using X-ray powder diffraction, Scanning Electron Microscopy–Energy Dispersive Spectroscopy, etc.