Definition and sustainability assessment of recycling processes for bonded rare earths permanent magnets used on wind generators

High-performance Permanent Magnets (PMs), both as sintered metal and bonded metal-polymer, are necessary for modern industry. PMs using Rare Earth Elements (REEs) for wind power generation provide efficiency and power density. As a drawback, REEs are critical due to cost, environmental and social impacts related to their production. Component optimisation and recyclability improvement are therefore a priority. The approach here described comes from the NEOHIRE European research project and it is aimed at providing secondary raw materials REEs for next generation products. For the case study of wind generators, innovative recycling processes are developed, focusing on the Neodymium Iron Boron alloys. Processes considered are manufacturing of bonded PM using recycled powders, recycling of sintered PMs into bonded through hydrogen decrepitation (HD), recycling of bonded PMs through ionic liquids dissolution and through alkali baking. A comparative environmental analysis of the processes is proposed by means of the Life Cycle Assessment (LCA) methodology, mainly using primary inventory data coming from real recycling demonstrators. According to the assumptions, recycling can significantly reduce the impacts of PM production in comparison with the manufacturing of similar components from primary raw materials.