The European Union has set itself the goal of achieving climate neutrality by 2050, a milestone that depends on the continent's ability to develop and implement clean energy and mobility solutions in a way that is both economically viable and environmentally sustainable. The amount of critical raw materials (CRM) needed to facilitate this energy transition is significant. In addition, industrial and household appliances will need to meet stringent energy efficiency standards to support this transition. The most energy-efficient electric motors and generators contain rare earth permanent magnets. While EU companies are world leaders in the production of electric motors, they are completely dependent on imports for the entire value chain of rare earth magnet materials. (Bernd Schaferet.al, A Report of the Rare Earth Magnets and Motors Cluster, Berlin 2021).

Rare earth elements (REEs) are essential components of these permanent magnets, which are critical for many applications that are vital to Europe's future. It is well known that REEs from China have been the main source for Europe, that supplies are uncertain, and that the Chinese production chain is generally unsustainable. At the same time, the demand for REEs for the production of new PMs is expected to double in 15 years.

In light of this data, our work focuses on the collection of EOL magnets and the sustainable recycling and reprocessing of PM from sources, concentrating on the most common and readily available source of economically recyclable electric motors: domestic appliances. We are developing new dismantling and recovery processes for PM on high-availability scrap and reprocessing lines. In HPMS (Hydrogen Processing of Magnetic Scrap)^1,2 we use an already established method of hydrogenation followed by grinding, degassing, and coating of sensitive powders. The HDDR (Hydrogenation-Disproportionation-Desorption-Regeneration)³ process has been implemented to simplify and minimize the steps in the recycling process.

Initial, ongoing pilot trials for the production of sintered and bonded magnets from recycled magnets confirm the waste-free, economic processing and future independence from unstable REE sources. For the production of sintered magnets, a new sustainable process of rapid consolidation is used, while for bonded magnets the most sensitive part to protect the reactive powders is the coating with a few monolayers of chemically bound coating precursor. In addition to magnetic measurements, various analytical techniques (SEM, HRTEM, XPS) are used to characterize the powders obtained by HPMS and HDDR processes, as well as the final magnets.

*This work is part of the “INSPIRES” project financed by EIT RawMaterials, Proposal Number 20090 (project website: https://eitrawmaterials.eu/project/inspires/).

Achieving a climate-neutral and circular economy by 2050 is a significant goal for Europe, emphasising innovation in clean energy and e-mobility. A major role in this transformation have permanent magnets (PM), vital in electric vehicles and renewable energy technologies. Despite their specialised market, they have a strategic impact on the EU's mobility sector and its dependence on imports. Given their critical role in numerous industrial and consumer applications, there is a pressing need for innovative approaches in their production and recycling.
For over 30 years, our research group at the Jožef Stefan Institute has led research and innovations in PMs, focusing on enhancing magnetic properties and efficient use of critical material resources. The most recent activities towards these goals are commonly referred to as grain-boundary engineering, focused on manipulating the non-magnetic two-dimensional-like grain boundary regions between the magnetic matrix grains to enhance the overall coercivity of the entire magnet. Simultaneously, we have explored various recycling and reprocessing strategies to enable the sustainable reuse of magnet waste into new functional magnets with only a little or negligible loss of overall magnetic performance. 
In this presentation, we will discuss several case studies illustrating how atomic-level structural and chemical analysis enhances our understanding of key physical and chemical mechanisms, which are essential for optimising magnetic performance and developing effective recycling strategies. For that purpose, we employed Advanced Transmission Electron Microscopy along with specialised analytical techniques such as Electron Energy-Loss Spectroscopy and Electron Holography, which provides quantitative magnetic characterisation at nanometer resolution. Among other findings, we will highlight how various grain-boundary structural refinement strategies during spark plasma sintering (SPS) influence the coercivity of Nd–Fe–B bulk magnets [1,2]. Additionally, we will discuss innovative electrochemical recycling techniques for sintered Nd–Fe–B PMs [3,4]. These techniques, which include direct recovery of the matrix phase and pure metal winning, are still emerging but have already shown promising results in our studies. 
 

Achieving a climate-neutral and circular economy by 2050 is a significant goal for Europe, emphasising innovation in clean energy and e-mobility. A major role in this transformation have permanent magnets (PM), vital in electric vehicles and renewable energy technologies. Despite their specialised market, they have a strategic impact on the EU's mobility sector and its dependence on imports. Given their critical role in numerous industrial and consumer applications, there is a pressing need for innovative approaches in their production and recycling.
For over 30 years, our research group at the Jožef Stefan Institute has led research and innovations in PMs, focusing on enhancing magnetic properties and efficient use of critical material resources. The most recent activities towards these goals are commonly referred to as grain-boundary engineering, focused on manipulating the non-magnetic two-dimensional-like grain boundary regions between the magnetic matrix grains to enhance the overall coercivity of the entire magnet. Simultaneously, we have explored various recycling and reprocessing strategies to enable the sustainable reuse of magnet waste into new functional magnets with only a little or negligible loss of overall magnetic performance. 
In this presentation, we will discuss several case studies illustrating how atomic-level structural and chemical analysis enhances our understanding of key physical and chemical mechanisms, which are essential for optimising magnetic performance and developing effective recycling strategies. For that purpose, we employed Advanced Transmission Electron Microscopy along with specialised analytical techniques such as Electron Energy-Loss Spectroscopy and Electron Holography, which provides quantitative magnetic characterisation at nanometer resolution. Among other findings, we will highlight how various grain-boundary structural refinement strategies during spark plasma sintering (SPS) influence the coercivity of Nd–Fe–B bulk magnets [1,2]. Additionally, we will discuss innovative electrochemical recycling techniques for sintered Nd–Fe–B PMs [3,4]. These techniques, which include direct recovery of the matrix phase and pure metal winning, are still emerging but have already shown promising results in our studies. 

Advancements in e-mobility and green power generation are crucial for fulfilling the Green Deal's objectives of creating a low-carbon society. Central to this goal are high-performing permanent magnets, such as Nd-Fe-B and Sm-Co, essential components in electric motors and generators. Consequently, intensive research into these magnets is critical to enhance their performance. However, a significant challenge is the scarce availability of these rare earth elements, designated as essential raw materials by the EU. Therefore, comprehensive approaches in resource-efficient processing, reprocessing, and recycling of these magnets are vital for the future development of permanent magnets. We are dedicated to researching and improving the viability of reprocessing and recycling Nd-Fe-B and other permanent magnets. Techniques such as electrochemical separation via anodic oxidation have successfully recycled Nd-Fe-B scrap into Nd₂Fe₁₄B matrix phase grains or break them down into rare earth-based precursors [1]. Moreover, Sm-Co permanent magnets have also shown promising recyclability through electrochemical methods [2]. Progress in scaling up recycling methods for Nd-Fe-B has been achieved through selective electrochemical and chemical approaches [3-4]. These innovative recycling and upcycling techniques pave the way for completely reengineering Nd-Fe-B magnets from the ground up, offering a break from traditional methods and potential enhancements in magnet performance metrics like energy products. Our current research also explores rapid consolidation methods, such as spark plasma sintering, which promise to advance Nd-Fe-B magnet development further [4].

The green transition drives the advancement of sustainable energy conversion technologies. Nd-Fe-B permanent magnets are crucial components of energy-efficient electric motors and generator systems. Presently, state-of-the-art magnets, boasting maximum energy products as high as 450 kJ/m³, are produced through powder metallurgy routes. However, conventional sintering is energy-intensive and offers limited control over microstructure formation and the final magnet's geometry.

Rapid powder consolidation techniques, like Spark Plasma Sintering (SPS), present notable advantages over conventional methods. They offer faster and more energy-efficient sintering processes, lower sintering temperatures, and the potential for net-shape manufacture, promising a new generation of Nd-Fe-B magnets with improved functionalities. Yet, due to the strong structure-properties dependence, consolidation of microcrystalline Nd-Fe-B-type powders via SPS proved challenging. Localized overheating at particle-particle contacts, owing to the Joule effect, can disrupt the delicate phase composition of the material, resulting in a drastic loss of hard-magnetic performance [1, 2]. 

Through careful optimization of heating conditions and the introduction of novel concepts in processing multiphase metallic systems like Nd-Fe-B, our research has been focused on developing alternative sintering strategies for the manufacture of Nd-Fe-B magnets. Fast sintering cycles have been employed to enhance the material's high-temperature performance by suppressing grain growth during densification. We will show that rapid sintering can reduce the energy consumption required to densify an Nd-Fe-B-type powder by an order of magnitude compared to slow conventional sintering. The new powder consolidation paradigms are applicable for processing both fresh and recycled powders, offering great potential for reengineering the magnet's microstructure, and having implications for future industrial processes.

The green transition drives the advancement of sustainable energy conversion technologies. Nd-Fe-B permanent magnets are crucial components of energy-efficient electric motors and generator systems. Presently, state-of-the-art magnets, boasting maximum energy products as high as 450 kJ/m³, are produced through powder metallurgy routes. However, conventional sintering is energy-intensive and offers limited control over microstructure formation and the final magnet's geometry.

Rapid powder consolidation techniques, like Spark Plasma Sintering (SPS), present notable advantages over conventional methods. They offer faster and more energy-efficient sintering processes, lower sintering temperatures, and the potential for net-shape manufacture, promising a new generation of Nd-Fe-B magnets with improved functionalities. Yet, due to the strong structure-properties dependence, consolidation of microcrystalline Nd-Fe-B-type powders via SPS proved challenging. Localized overheating at particle-particle contacts, owing to the Joule effect, can disrupt the delicate phase composition of the material, resulting in a drastic loss of hard-magnetic performance [1, 2]. 

Through careful optimization of heating conditions and the introduction of novel concepts in processing multiphase metallic systems like Nd-Fe-B, our research has been focused on developing alternative sintering strategies for the manufacture of Nd-Fe-B magnets. Fast sintering cycles have been employed to enhance the material's high-temperature performance by suppressing grain growth during densification. We will show that rapid sintering can reduce the energy consumption required to densify an Nd-Fe-B-type powder by an order of magnitude compared to slow conventional sintering. The new powder consolidation paradigms are applicable for processing both fresh and recycled powders, offering great potential for reengineering the magnet's microstructure, and having implications for future industrial processes.