Rainbow Rare Earths Ltd. says that three-quarters of the process flowsheet for its Phalaborwa rare earths project in South Africa has now been fixed and moved into the engineering phase of the definitive feasibility study.
The update follows pilot plant operations through the first half of 2026, with recovered data now feeding into the DFS design. Rainbow said test work at its in-house Johannesburg laboratory had simplified the project’s flowsheet, with final optimisation of the solvent extraction circuit still underway.
Major changes since the preliminary economic assessment include replacing hydraulic reclamation with mechanical reclamation, eliminating the weak acid leach circuit, cutting the counter-current leach from three stages to two and reducing residence time from 32 hours to 8 hours. The number of capital-intensive horizontal belt filters has also been reduced from 14 to 8.
The company has also replaced continuous ion chromatography with solvent extraction, which it described as a proven industry-standard separation process. Its continuous ion exchange circuit achieves a ninefold concentration in rare earth elements, reducing flow from around 300 cubic metres per hour as pregnant leach solution to less than 40 cubic metres per hour into impurity reduction and less than 5 cubic metres per hour into the separation circuit.
Technical director Dave Dodd said Rainbow had “successfully finalised the flowsheet to the point that it delivers a mixed rare earth feed to the SX separation process”.
Rainbow said Phalaborwa is intended to become the first commercial recovery of rare earth elements from phosphogypsum, a waste product from phosphoric acid production, with the final circuit expected to produce NdPr oxide and SEG+ Group at 99.5% purity, alongside commercial quantities of dysprosium, terbium and yttrium.
