NdFeB magnet recycling by non conventional sintering processes – SinterMagRec

Rare Earth-Iron-Boron (RE-FeB) magnets are high-performance components of electric motors. With the development of electric or hybrid cars, that of wind mills and hydro-wind turbines, the need for such magnets is expanding significantly. In 2010/11, the wind turbine industry used 11,540 tonnes of magnets. In 2013, 37,000 tons of rare earth magnets were also used for the manufacturing of electric and hybrid cars.
The demand for Rare Earth elements is increasing drastically : for Neodymium, it is expected to grow by 700% over the next 25 years. Current supply sources should therefore not be sufficient to meet this trend. Moreover, the Rare Earths market is subject to extremely volatile prices, reflecting geopolitical tensions and the strategic game of producing countries, especially China.
Among the various solutions to reduce the competitive access to Rare Earths for magnet production, recycling appears as a promising way. Wastse of Electrical and Electronic Equipments (WEEE) in Europe represent an untapped supply of Rare Earths. The exploitation of these "urban" deposits is therefore a major factor to ensure European independence. The circular economy which gives rise to products with a second life is also widely supported by the European Commission, which has fixed, by decree, collection targets that are constantly increasing for the coming years: by 2015, a collection rate of 40% has been achieved, 85 % is set for 2019.
The main objective of this project is to develop new magnets from recycled REFeB magnet powders collected in urban mines. In the proposed process, sintered magnets collected in WEEE are, first, pulverised into REFeB powders. In a second step, the development of non-conventional sintering techniques using the powder opens up an interesting valorization perspective. Two technologies are possible in order to develop the microstructure and the magnetic properties in a new magnet REFeB: microwaves or SPS (Spark Plasma Sintering). These non-conventional sintering processes have significant advantages over conventional sintering processes, such as: processing time and temperature reduction, very fast heating rates, and a reduction in energy consumption.
Thus, within the framework of the proposed study, attention will be given to:
• Study and understand the mechanisms of flash sintering by microwave and SPS. Powders of precursors will be produced by mechanical milling and solid state reactions (the so-called hydrogen decrepitation process),
• Study the influence of the induced microstructure on magnetic properties
• study the development of anisotropy of magnetic properties by controlling materials texturing
• characterize the functional properties of the produced magnets in real devices (electric machines).