The upstream rare earth resources of Malaysia: Insight into geology, geochemistry, and hydrometallurgical approaches

Peninsular Malaysia is already well known for having rare earth (RE) resources. However, pertinent data and information on upstream RE resources and reserve potential in Malaysia are yet to be established. It is vital to identify opportunities and challenges for value addition to rare earth elements (REEs) deposits in Malaysia. Therefore, this study evaluates the potential of Malaysian geological formations to serve as repositories for RE resources, such as rare earth minerals (REMs) and REEs, by elucidating the geological processes that are considered critical to the formation of the various deposit types. This paper concisely reviews possible REE mineralization in alkaline igneous rocks, pegmatites, placer deposits: monazite and xenotime, marine sediments, river and lake sediments, ion adsorption clays (IAC) deposits, and shale/coal deposits found in Malaysia. Comparisons between Malaysian deposits revealed that these deposits are potentially enriched with RE resources showing geological formations across the world. The paper reviews the methods and flowsheets used for the recovery of REMs and REEs from primary, secondary as well as alternative resources, with special consideration to the hydrometallurgical procedures comprising of leaching with acids and alkalis tailed by ion exchange, solvent extraction, or precipitation. The REEs ecosystem of Malaysia has also been discussed by considering the latest information from the Malaysian Investment Development Authority (MIDA), the REEs processing center, the Academy of Science of Malaysia (ASM), the People's Republic of China (PRC), Lynas Malaysia Sdn. Bhd. (Lynas), Ministry of Energy and Natural Resources (NRECC), Jabatan Mineral & Geosains (JMG), Ministry of Science, Technology, and Innovation (MOSTI), and the Malaysian Chamber of Mines. The information on upstream RE resources and recent hydrometallurgical approaches provided in this study will contribute to developing and enhancing midstream and downstream RE-based manufacturing and processing operations in Malaysia.