Rainbow Rare Earths has selected solvent extraction as the final processing route for its Phalaborwa rare earths project in South Africa, in what the company described as a major de-risking step for the development.
The decision follows a pre-feasibility review by Australia’s ANSTO, the specialist minerals research body, which confirmed that solvent extraction — the dominant method used globally to separate rare earth elements — is capable of producing neodymium-praseodymium (NdPr) oxide and a SEG+ mixed rare earth product at purities exceeding 99.5 per cent. The company also issued a correction to previously released production figures for its SEG+ product.
Phalaborwa, which aims to extract rare earths from phosphogypsum waste stacks rather than a conventional orebody, has been promoted by Rainbow as a low-capital, lower-risk alternative to traditional mining projects. The adoption of solvent extraction allows the company to finalise its flowsheet and advance towards a definitive feasibility study, with construction and first output still targeted for 2027 and 2028 respectively.
ANSTO, which also worked on earlier test phases at Phalaborwa, was tasked with modelling the two-stage extraction circuit needed to convert Rainbow’s high-grade mixed rare earth product into saleable NdPr oxide and a high-purity SEG+ carbonate. Engineering work on the separation plant is being carried out with METC Engineering.
George Bennett, Rainbow’s chief executive, said the confirmation of solvent extraction as the preferred route marked “an important de-risking step” for the project, adding that optimisations achieved in the front-end flowsheet had enabled the design of a smaller, more efficient circuit.
Technical director Dave Dodd said the choice aligned the project with global industry practice, noting ANSTO’s long-standing role in designing separation circuits for a number of Western rare earth ventures. “We are very comfortable with these technologies,” he said, adding that the confirmation of the process design would allow Rainbow to complete the feasibility study on schedule.
We caught up with CEO George Bennett at the 2024 Mining Indaba conference in Cape Town. He provided an update on Rainbow’s operations, but also told us about the many uses of rare earths and why they are so important in the global energy transition.