Model-Based Comparison of Recycling Processes for Grinding Slurries from NdFeB-Magnet Production

Grinding slurries occur as residual output of the production process of neodymium-iron-boron-magnets. They occur in particular in the grinding process which is the final shaping process step. As the magnetic alloy contains a high share of critical raw materials such as the rare earth elements neodymium, praseodymium or dysprosium, the recycling of the grinding slurries may reduce the demand for primary rare earth elements. Currently, recycling is one of the alternatives discussed as a solution for a sustainable supply chain independent from China which is currently the main supplier. State of the art in the processing of grinding slurries in Europe is the inertization of the grinding slurries followed by an export for further processing abroad. A recent research approach carries out an alternative recycling process, which allows for the separation of rare earth elements and accompanying elements of the magnetic alloy by pyrometallurgical treatment. In this study, both processes are compared regarding their material flows as well as their demand for consumables and energy within a model-based comparison. The study aims at giving a first, elementary evaluation of the alternative recycling process, to identify strengths and weaknesses and to raise questions that must be answered prior to the industrial implementation of the process.