The polymeric binder of bonded NdFeB magnets can be dissolved in ionic liquids with strongly coordinating anions and the magnetic powder can be reused for manufacturing of new magnets.

Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the NdFeB breaks down into a matrix phase (Nd 2 Fe 14 BH x ) and RE-rich grain boundary phase. The grain boundary phase in the HD powder is <2 µm in size. Recycled NdFeB material has a higher oxygen content compared to the primary source material. This additional oxygen mainly occurs at the Rare Earth (RE) rich grain boundary phase (GBP), because rare earth elements oxidise rapidly when exposed to air. This higher oxygen level in the material results in a drop in density, coercivity, and remanence of sintered NdFeB magnets. The particle size of the GBP is too small to separate by sieving or conventional screening technology. In this work, an attempt has been made to separate the GBP from the matrix phase using a hydrocyclone, and to optimise the separation process. HD powder, obtained from hard disk drive (HDD) scrap NdFeB sintered magnets, was used as a starting material and passed through a hydrocyclone a total number of six times. The X-ray fluorescence (XRF) analysis and sieve analysis of overflows showed the matrix phase had been directed to the underflow while the GBP was directed to the overflow. The optimum separation was achieved with three passes. Underflow and overflow samples were further analysed using an optical microscope and MagScan and matrix phase particles were found to be magnetic.

Volatile prices and severe supply-demand issues have led to the development of a significant research area in terms of reuse and recycle of rare earth permanent magnets. Another reason for the proliferation of this research is the increased emphasis on environmental impacts of rare earth material mining which can be substantially reduced by reuse and recycling. This paper develops a methodology and analysis tool to apply direct reuse and recycled rare earth magnets into electromobility. Easy assembly and disassembly of permanent magnets has been presented for a permanent magnet based claw-pole machine so as to directly reuse the recovered magnets. Secondly, utilization of recycled magnets fabricated by hydrogen decrepitation in the claw-pole machine has been analyzed and compared with a machine with virgin magnets. Energy consumption of the machine with virgin and recycled magnet have been evaluated for two vehicle drive cycles and it is observed that the consumption is almost the same for the machine with both magnet types. The results indicate that new age electrical machines for this application of electro-mobility can utilize recycled magnets which in turn lead to lesser impacts on the environment due to reduced mining of new rare earth minerals.

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