Sustainable Value Recovery of Rare Earth Magnets: Economic and Environmental Strategies

Neodymium-iron-boron (NdFeB) magnets offer the strongest magnetic field per volume that is not possible with other commercial magnets. Therefore, they are widely used in a variety applications such as electric vehicle motors, wind turbine generators, and defense products. However, supply of the materials, primarily rare earth elements, is uncertain as they are heavily dependent on imports from outside the United States. To alleviate the supply risk and promote circular economy, researchers are developing novel technologies to recover value from end-of-life products. To assist with this effort, life cycle assessment was performed for NdFeB magnets to quantify the environmental impacts of virgin magnet production in comparison with magnet-to-magnet recycling. Magnet-to-magnet recycling was found to lower the environmental footprint of NdFeB magnet production by 64-96% for ten impact categories under investigation. Important questions such as what the bottlenecks are and how to further improve the environmental performances were addressed. To assist with the reverse logistics, mathematical models were developed to identify the optimal facility locations, capacities, and transportation flows with the goal of maximizing the profit, environmental benefits, and social support. Both global optimization and heuristics approaches were developed, whose solutions were compared for the solution quality and computational efficiency. These efforts serve to increase the supply of critical materials by facilitating an effective value recovery supply chain, reducing wastes, and aligning the industry with circular economy.