Rainbow Rare Earths Ltd (LSE:RBW, OTC:RBWRF) said it has successfully produced mixed rare earth sulphate for the first time from gypsum at its Phalaborwa pilot plant in South Africa.
The sulphate met the required purity and grade and included all four of the critical 'magnet' rare earths, neodymium, praseodymium, dysprosium and terbium, said the statement.
Overall recoveries of 65% were in line with the expectations of the Preliminary Economic Assessment, it added, with the sulphate to be used as feed for the back-end pilot plant built at K-Tech facilities in Florida for final processing into separated rare earth oxides.
In South Africa, the front-end pilot plant will run for an additional quarter to further optimise recoveries and cost-base, Rainbow added.
George Bennett, chief executive, said production of the sulphate validated Rainbow's strategy to recover rare earth elements from phosphogypsum stacks, de-risks Phalaborwa and opens up opportunities to apply the technology to other similar phosphogypsum resources globally, such as at the Mosaic Uberaba stack in Brazil.
Producing separated rare earth oxides later this year in the US will be the final de-risking step, he added, and will prove Rainbow can take its product all the way through the production process.
“Given the importance of Phalaborwa, we are delighted to have recently increased our stake in the project to 85% and have a clear path to owning 100% in the near term.”