Rainbow; something of a pioneer.5 Sep 2025 21:03
South Africa streaks ahead with exceptionally pure rare earth optimised in Joburg lab
1st September 2025
JOHANNESBURG (miningweekly.com) – South Africa has delivered what is described as “an exceptionally pure rare earth product”, which has been optimised in a Johannesburg laboratory.
The breakthrough is part of the rare earths recovery project work under way in South Africa, led by Rainbow Rare Earths CEO George Bennett, who on Monday September 1 reported successful results from ongoing testwork for the Phalaborwa project under way in Limpopo province.
This very distinctive project, which has attracted favourable global attention, encompasses the recovery and separation of rare earth elements (REE) from phosphogypsum stacks, a waste product from phosphoric acid production, meaning that many of the costs, risks and long timescales associated with traditional mining projects are eliminated.
Key components of Rainbow’s Johannesburg in-house laboratory testwork have been to maximise and maintain overall REE recovery at 65% while achieving impurity rejection through continuous ion exchange (CIX).
The key delivery of a high-grade, low-impurity feed stream to the final separation process to separate rare earth oxides of the desired purity level has been successfully achieved by Rainbow’s in-house team. The purification process combining CIX and precipitation steps is a novel combination in REE recovery and demonstrates the special intellectual property in REE extraction that the company has developed.
The incorporation of CIX and simplified final separation of only two products is expected to result in modest capital expenditure (capex) and operational expenditure (opex) for this part of the circuit.
At 65%, the recovery of REE from the phosphogypsum feed to the mixed REE product has been in line with recoveries used in the recent interim economic study. These results have been confirmed further through extensive large-scale repetitive batch testing with solution recycle.
Savings in power, reagent, labour and capital costs are expected to be brought about by trade-off studies to optimise the primary leach circuit.
Moreover, the results of trade-off studies will provide the market with an update as to the potential impact on capex and opex ahead of the publication of the project’s definitive feasibility study.
As reported by Mining Weekly last year, Rainbow’s advance is regarded as being one of the world’s most resilient rare earths projects at a time when these elements are in growing demand for use in permanent magnets to help the world go green.
Moreover, the commercial recovery of REEs from phosphogypsum makes Rainbow something of a pioneer.
Displayed on a large screen during a presentation at Mintek were an old opencast mine that had been mined for many years, an old Sasol phosphoric acid plant that had not been operating for ten years and two unlined environmentally hazardous gypsum stacks.
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