This report considers the strategic importance and growing global demand for rare earth elements (REEs), vital components for many high-tech consumer devices and defence applications. They are also a crucial component of the energy transition and are used in renewable energy technologies such as solar panels, wind turbines, electrolysers, and electric vehicles.
Many studies have focused on the recovery REEs from different coal-related materials including hard coal and lignite, coal refuse, mine drainage, and coal combustion by‑products such as fly ash. A wide range of techniques for extracting REEs have been proposed or trialled, such as physical beneficiation, acid leaching, ion-exchange leaching, bioleaching, thermal treatment, alkali treatment, solvent extraction, and more novel concepts.
Coal geology and chemistry, chemical engineering, process development, and extractive metallurgy support the development of possible extraction processes. Data generated by these combined efforts are allowing various REE recovery concepts to progress from feasibility studies to laboratory- and pilot‑scale investigations. Several processes are moving towards initial commercial production. However, many processes have only been evaluated at limited scale and lack hard data on their economic viability and possible environmental impact. Some require further technical development and optimisation. More fundamental research continues into recovery processes less reliant on the use of aggressive conditions that often include the use of strong acids, alkalis, and organic solvents.
REE recovery from coal-based materials is an evolving field. Significant achievements have been made during the past decade, but their extraction remains challenging. For any recovery scheme to be considered viable, it will need to strike the right balance between efficiency, cost, and environmental impact. This report examines the more established methods for extracting REEs from coal-based materials, reviews some of the more promising novel techniques being developed, and considers progress being made towards the possibility of them becoming feasible alternatives to conventional mineral ores.
There is a big incentive to achieve viable REE recovery from coal-based materials – successful development would help diversify sources, ease concerns over current and future market domination, and help progress towards technologies effective in mitigating climate change.
