New recycling process for rare-earth elements could transform green technology and boost carbon neutrality

In a recent study published in Engineering, researchers from Kyoto University have unveiled a novel method for the efficient separation and recycling of rare-earth elements (REEs) from end-of-life magnets. This innovative process, known as the selective extraction–evaporation–electrolysis (SEEE) process, promises to significantly advance recycling technology and support global efforts towards carbon neutrality.

REEs, particularly neodymium (Nd) and dysprosium (Dy), are essential components in high-performance magnets used in various green technologies, including electric vehicles (EVs) and wind turbines. With the surge in demand for these technologies, efficient recycling of these critical materials has become crucial. The new SEEE process addresses this need by offering a highly efficient and environmentally friendly alternative to traditional hydrometallurgical techniques.

The study, led by professor Toshiyuki Nohira and his team at the Institute of Advanced Energy, Kyoto University, explores how this new process can transform the recycling of Nd magnets, which are widely used in energy-efficient technologies. Traditional recycling methods often involve complex and energy-intensive processes with substantial environmental impact. In contrast, the SEEE process is designed to be more sustainable and precise.

The SEEE process involves three key stages:

1. Selective extraction: Using a molten salt mixture, including calcium chloride (CaCl₂) and magnesium chloride (MgCl₂), the process extracts REEs from magnet scraps. The addition of calcium fluoride (CaF₂) helps to control evaporation losses and improve extraction efficiency.

2. Selective evaporation: The process then removes any remaining extraction agents and byproducts, concentrating the REEs.

3. Selective electrolysis: Finally, the extracted REEs are separated electrochemically based on their different formation potentials. This step enables the recovery of high-purity Nd and Dy metals.

The results of this study are promising. The SEEE process achieved recovery rates of 96% for Nd and 91% for Dy, with both metals reaching purities exceeding 90%. This level of efficiency and precision in separating and recycling these critical elements is a significant advancement over current methods.

The implications of this research are far-reaching. As the demand for electric vehicles and renewable energy sources continues to grow, so does the need for effective recycling solutions. The SEEE process could play a pivotal role in ensuring a stable supply of REEs while reducing dependency on new mining activities, which often have significant environmental costs.

Furthermore, the SEEE process is not limited to recycling Nd magnets. The researchers believe that it could be adapted for other applications, such as the reprocessing of nuclear fuels, expanding its potential impact across different sectors. While the SEEE process has demonstrated considerable potential, the researchers acknowledge that further technical investigations are needed to fully integrate it into industrial applications. Nevertheless, the initial results mark a significant step forward in the field of material recycling and environmental sustainability.

The study highlights the critical role of advanced research in developing solutions that align with global environmental goals. As the world moves towards a more sustainable future, innovations like the SEEE process are essential in overcoming the challenges associated with REE recycling and supporting the broader transition to carbon-neutral technologies.

The paper “Highly Efficient and Precise Rare-Earth Elements Separation and Recycling Process in Molten Salt,” authored by Hang Hua, Kouji Yasuda, Yutaro Norikawa, Toshiyuki Nohira. Full text of the open access paper: https://doi.org/10.1016/j.eng.2022.12.013. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

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