Rainbow Rare Earths has successfully produced an exceptionally pure mixed rare earth carbonate (MREC) using its proprietary continuous ion exchange (CIX) process at its Phalaborwa project in South Africa.

The company’s in-house laboratory in Johannesburg has successfully optimised its proprietary continuous ion exchange (CIX) process. The result is the production of an exceptionally pure mixed rare earth carbonate (MREC), a crucial intermediate product in REE refining. Across multiple test samples and campaigns, this MREC has averaged over 55% total rare earth oxides (TREO) – far exceeding the industry standard of >42% TREO for refinery feedstock.

Moreover, the TREO purity of the MREC has now consistently achieved levels of >93%, compared to the commonly accepted benchmark of >90%. This high-grade and low-impurity feedstream marks a critical step toward achieving separated rare earth oxides (REO) of the required purity for use in advanced technologies.

“This purified product delivers a mixed rare earth carbonate (‘MREC’) averaging >55% total rare earth oxides (‘TREO’) across multiple test samples/campaigns, considerably exceeding the rare earth industry’s typical refinery specification of >42% TREO,” according to the company statement.

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The quality of Rainbow’s purified mixed REE product stands alongside the highest-grade MREC specifications produced globally. With continuous ion exchange proving both effective and scalable, Rainbow has now begun detailed modelling and updated costing for the final separation process, based on this high-purity feedstock. These steps mark a substantial advancement of the Phalaborwa project.

Key progress includes:

• Reduction in pregnant leach solution (PLS) volume from 340 m³/hour to just 7–10 m³/hour – significantly optimising the feed into the final separation circuit.
• Ongoing development of the final flowsheet to achieve product purities of up to 99.5%, targeting high-purity separated REE products.
• Work on the Definitive Feasibility Study (DFS) for the primary leach flowsheet is progressing well. This section of the project accounts for approximately 85–90% of the total project Capex.
• Recent trade-off studies are being incorporated into the DFS and are expected to deliver further capital and operational savings.

CEO George Bennett commented: “These results represent significant progress for the Phalaborwa project, confirming the potential to become a very low-cost producer of light and heavy REE and one of the highest-margin projects in development globally. They also validate our decision to finalise our flowsheet test work in-house and demonstrate that we have developed the expertise to address REE extraction and separation in a highly efficient manner.”

Strategic Importance Amid Rising Global Demand

As the global spotlight intensifies on the need for secure and diversified rare earth supply chains, the Phalaborwa project is emerging as a potential linchpin in western efforts to reduce dependency on traditional suppliers.

“The West is finally recognising the importance of REE, used in permanent magnets vital to the functionality of many of the products that underpin 21st-century society, as well as to emerging and advanced technologies,” Bennett noted.

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He highlighted a growing alignment between industry and government, referencing the recent offtake agreement between MP Materials and the U.S. Department of Defence, which set a floor price of US$110/kg for NdPr – a key rare earth magnet material. This benchmark is notably higher than current market prices, underscoring the need for pricing that supports new production capacity.

“Whilst Rainbow’s project is very robust at current REE pricing and is expected to deliver a positive EBITDA, we are therefore very comfortable with this benchmark floor price set by MP Materials, as it is the same price used for NdPr in Rainbow’s updated December 2024 interim economic assessment of Phalaborwa, which demonstrated the project would generate ca. US$181 million annual EBITDA once in production,” Bennett added.