Weathering of carbonatite REE deposits (WREED): a critical stage in generation of critical metal resources

The rare earth elements (REE), and in particular neodymium and dysprosium, are essential for renewable energy devices such as wind turbines and the development of electric motors for transport.

Current national and international objectives for decarbonisation of energy generation and transport, mean that the future increased supplies needed cannot be met from existing sources or recycling.

Global supply chains, the localisation of currently exploited resources, processing facilities and expertise in China and increasing demand mean that there is a need for global research partnerships in this area, with Chinese partners as a hub for knowledge exchange.

This project will form a new UK-Chinese and global partnership to investigate the processes controlling concentration of REE in weathered carbonatite deposits. We will host workshops to define the current state of knowledge and carry out preliminary analyses to identify new techniques to improve our understanding of how these resources form.

The majority of the world's supply comes from two rock types - carbonatites (carbonate rocks crystallised from magma), and deeply weathered granites. Carbonatites are extracted via traditional hard rock mines, whilst weathered granite deposits involve leaching of low concentration material, which has caused significant environmental impact in China. Weathered carbonatite deposits may have the highest concentrations of metals, and are easy to extract but may be difficult to process. The weathering process can enrich the most desirable REE and may separate them from radioactive elements.

At present the REE are sourced from either low concentration weathered granitoid (ion adsorption clay) deposits in southern China, or from high concentration carbonatite-related deposits, especially the World’s dominant REE mine in hard-rock, altered carbonatite at Bayan Obo, China, but also including the Mt Weld weathered carbonatite, Australia. Weathered carbonatites (e.g. Tomtor, Russia; Mount Weld, Australia) are some of the world’s richest REE deposits.

Low concentrations in weathered granitoid deposits involve large tonnage extraction or leaching of near-surface materials, both of which have caused significant environmental impact in China. Extraction from bedrock deposits require extensive rock crushing and mineral processing.

China is well-endowed with REE deposits but producing REE in an environmentally sustainable way has been a major challenge. Issues of land use, processing and also the actinide concentration in REE ores significantly impact the potential to extract a given resource. Weathered carbonatite deposits may have the highest concentrations of metals, are easy to extract but difficult to process. They have the potential for beneficial inter-element fractionations that enrich the most desirable REE and may separate them from actinides.

This project will form a new partnership to investigate the processes controlling concentration of REE in weathered REE carbonatite deposits.