Recycling and substitution of light rare earth elements, cerium, lanthanum, neodymium, and praseodymium from end-of-life applications - A review

Abstract

The light rare earth elements (LREEs) lanthanum, cerium, neodymium and praseodymium are increasingly used in renewable energy technology and are applicable in portable electronic devices, such as phosphors in lightning applications and in catalysis. The extraction of REEs from virgin ores causes environmental degradation. LREEs are considered as critical metals. To overcome the environmental and criticality challenges of LREEs, recycling presents means by which they can be obtained from secondary sources. Presently, the recycling rate of LREEs is still very low. Substitutes of LREEs in most cases are either inferior or still undiscovered. This study investigates the criticality challenges and environmental impacts of producing LREEs from virgin ores. It focuses on LREEs obtainable in selected end-of-life products considered to have significant recycling potential; these include NdFeB magnets, Ni-MH batteries, phosphors in lighting and catalysts. Current recycling technologies, including representative methods and current recycling challenges are also reviewed. Although current recycling technologies have recorded growth, there is still a need for further improvements. The article highlights current LREEs substitution advances and the faced challenges in finding suitable LREEs substitutes. Furthermore, future ways to promote sustainability of LREEs recycling, to improve substitution, and to tackle the criticality challenges of LREEs are proposed.