Rainbow Rare Earths has begun pilot-scale operations in Johannesburg, marking the final phase of process test work for its Phalaborwa rare earths project in South Africa. The programme is designed to validate a revised flowsheet ahead of the project’s definitive feasibility study and to support third-party verification for project financing.
The pilot plant will operate through the first half of 2026 and will generate data for process design, mass balance, equipment sizing and capital and operating cost estimates. It will also produce bulk material for off-site solvent extraction testing, intended to confirm the separation of neodymium and praseodymium (NdPr) oxide and a mixed medium and heavy rare earth product (SEG+) at purities above 99.5 per cent.
Phalaborwa is intended to be the first commercial project globally to recover rare earth elements from phosphogypsum, a waste by-product of phosphoric acid production. The company says this approach avoids many of the costs, permitting risks and long development timelines typically associated with conventional rare earth mining.
The Johannesburg pilot plant is located at Mintek, South Africa’s national mineral research organisation. It will operate a fully optimised leach circuit, producing pregnant leach solution that feeds into a pilot-scale continuous ion exchange and impurity removal process developed using Rainbow’s proprietary technology.
Since the conclusion of an earlier pilot programme in mid-2024, Rainbow has made a series of changes to the Phalaborwa flowsheet aimed at improving efficiency and reducing costs. These include the introduction of ion exchange and impurity precipitation stages, which significantly reduce volumetric flow to the solvent extraction circuit and allow for a simpler and lower-cost separation design.
Further optimisation of the leach process has reduced the number of stages from three to two, shortened residence time from 32 hours to eight, halved the number of filters required and lowered heating requirements. The company expects these changes to have a positive impact on both capital expenditure and operating costs.
George Bennett, Rainbow’s chief executive, said the pilot programme would demonstrate a flowsheet that has undergone “substantial optimisation” over the past 18 months and would underpin completion of the feasibility study later this year.
The bulk sample generated by the pilot plant will be used in off-site solvent extraction trials to finalise product specifications, a step that Rainbow says is important for securing offtake agreements.
The pilot programme begins as prices for key rare earth elements recover from recent lows. NdPr oxide prices have risen to above $100 per kilogram, roughly double levels seen in 2025, amid tighter supply and continued efforts by western governments to develop alternative supply chains outside China. Prices for some medium and heavy rare earths have also strengthened following the introduction of Chinese export controls.
Phalaborwa is backed by the US International Development Finance Corporation, reflecting its strategic importance to rare earth supply diversification.
Rainbow plans to host investor site visits to its laboratory and pilot plant facilities in early February, ahead of the Mining Indaba conference.
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.