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REE processing routes for bastnäesite, monazite and xenotime. Figure after Smith et al. (2017).
Processing
Processing
After mining, REE ores are processed to increase their REE content. Initial concentration is normally undertaken at, or close to, the mine site and involves crushing the ore and separating REE-bearing ore minerals from the gangue (uneconomic) minerals, using a range of physical (e.g. magnetic separation and froth floatation) processes that depend on the ore type being processed. Chemical processes (e.g. calcining and acid leaching) are used to further separate the REE from their ore minerals. Separation of the individual REE from each other is challenging due to their similar chemical properties; however, selective oxidation or reduction and hydrometallurgy (i.e. typically ion exchange and solvent extraction) have been successfully employed to separate the individual REE.
Hydrometallurgical processing is commonly used to separate and purify REE according to the following three stages:
Dissolution of the rare earth content in acid, sometimes at elevated pressure and temperature.
Separation of the different REE into pure and concentrated solutions, by solvent extraction or ionic liquid extraction and ion exchange. The separation of the individual REE is the most difficult part of the whole REE value chain.
Generation of individual and pure rare earth elements.
Processing of REE ores and concentrates to produce REE-metals and REE-chemicals (e.g. oxides, carbonates and nitrates, etc.) predominantly occurs in China, which accounts for more than 80% of REE processing. However, there is processing capacity in Japan, India, Malaysia and Russia, with REE-refining plants also planned in Norway, Sweden, the United Kingdom, Canada and the United States (see table below).
Table showing current (operational) REE processing locations and locations where REE refining is planned to take place, and the type of REE-products being produced. Table compiled by Richard Shaw (BGS).
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