Rare-earth metals, particularly neodymium, dysprosium, and praseodymium are becoming increasingly important in the transition to a green economy due to their essential role in permanent magnet applications such as in electric motors and generators. With the increasingly limited rare-earth supply and complexity of processing Nd, Dy, and Pr from primary ores, recycling of rare-earth based magnets has become a necessary option to manage supply and demand. Depending on the form of the starting material (sludge or scrap), there are different routes that can be used to recover neodymium from secondary sources, ranging from hydrometallurgical (based on its primary production process), electrochemical to pyrometallurgical. Pyrometallurgical routes provide solution in cases where water is scarce and generation of waste is to be limited. This paper presents a systematic review of previous studies on the high-temperature (pyrometallurgical) recovery of rare earths from magnets. The features and conditions at which the recycling processes had been studied are mapped and evaluated technically. The review also highlights the reaction mechanisms, behaviors of the rare-earth elements, and the formation of intermediate compounds in high-temperature recycling processes. Recommendations for further scientific research to enable the development of recovery of the rare-earth and magnet recycling are also presented.

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Review of High-Temperature Recovery of Rare Earth (Nd/Dy) from Magnet Waste

Critical thermodynamic evaluation and optimization of the Fe–B, Fe–Nd, B–Nd and Nd–Fe–B systems

In this article, an amorphous Fe rich amorphous structure designed based on a competitive atomic cluster model was synthesized and characterized successfully. The constituent zero-valent iron (ZVI) has excellent activity and efficiency for decolorization of Orange G (OG) solution at room temperature. The decolorization is characterized by UV-vis spectrum and pseudo-first-order kinetics. The X-ray Micro fluorescence spectrometer, Inductively Coupled Plasma Optical Emission Spectrometry, and Scanning Electron Microscope were employed to trace the ZVI. The consumption of ZVI destabilizes the local atomic arrangement and yields the phase separation of Fe at the surface and responds to the high activity and the catalysis for decolorization. This observation is in accordance with the change of k1 0.011 min–1 to k2 0.047 min–1, which is supported by the cyclic decolorization test. This work provides a new strategy to design multifunctional metal materials and indicates their brilliant future in practical applica...

Synthesis of an Fe rich amorphous structure with a catalytic effect to rapidly decolorize Azo dye at room temperature.

Critical evaluation and optimization of all available phase diagram and thermodynamic data for the Fe-RE (RE = La, Ce, Pr, Nd and Sm) systems have been conducted. The thermodynamic properties of the liquid phase and solutions were described using the modified quasichemical model and the compound energy Formalism, respectively. The magnetic properties of solid phases were also taken into account. In order to obtain more accurate thermodynamic description, the systematic changes in the phase diagrams and liquid enthalpy of mixing along the lanthanide series were considered in the evaluation of experimental data.

K. Han

Papers

The Fe-Y (iron-yttrium) system

The Fe-Nd (Iron-Neodymium) system

A case of giant esophageal cancer underwent surgical resection after chemotherapy combined with immunotherapy.