London-listed Rainbow Rare Earths has produced the first magnet rare earth elements (REE) in a saleable form at its Phalaborwa project, in Limpopo, South Africa.

This paves the way for the first commercial recovery of REE from phosphogypsum, the company reports.

Rainbow has, as part of work to complete a definitive feasibility study (DFS) for the project, been working to optimise the primary front-end leach flowsheet.

The primary front-end leach flowsheet, which represents about 75% of the Phalaborwa flowsheet and processes phosphogypsum to produce a high-grade rare earth feed stream for the separation process, has been subject to an extensive programme of bench scale and pilot plant leach testwork conducted at the Johannesburg facilities of the Council for Mineral Technology, also known as Mintek.

This has resulted in the delivery of a simplified leach flowsheet with a smaller footprint and expected capital and operating cost benefits versus the flowsheet set out in the project’s preliminary economic assessment (PEA).

Rainbow says the optimised flowsheet maintains the overall recovery rate of rare earths at about 66%.

“I am very proud of our team's extensive and hard work to establish and optimise the primary front-end leach flowsheet at Phalaborwa, which has delivered a simplified process to recover REEs from phosphogypsum versus that published in our PEA,” comments Rainbow CEO George Bennett.

Meanwhile, the rare earth oxide separation flowsheet, which represents about 25% of the Phalaborwa flowsheet and refines the mixed rare earth feed stream into separated rare earth oxides, has been tested through a combination of bench scale ion exchange/ion chromatography and pilot plant continuous ion exchange (CIX)/continuous ion chromatography (CIC) at the facilities of K-Technologies, in Florida, in the US.

The separation pilot plant has, to date, achieved proof of concept, with the CIC delivering a separated neodymium and praseodymium (NdPr) oxide with about 96% purity.

Rainbow points out that market enquiries show that this is a saleable product, with a normal impurity discount as seen in other metals. The company is, however, also continuing work to optimise the process to achieve oxide purity of more than 99%.

It further notes that a review of the waste or recirculating streams from the CIX/CIC testwork has shown that the leach and separation processes need to be integrated on the same site to allow for the recycling of critical streams from the separation process to the appropriate destinations in the leach plant and relevant disposal of waste material.

Rainbow has, therefore, decided to fast-track the relocation of the CIX/CIC pilot plant to South Africa.

The company says the various workstreams required as part of the DFS are well advanced, but cautions that completion of the final DFS is dependent on the finalisation of the separation testwork for the project.  

It warns that this places the initial timeframe for completing the DFS in the first half of 2025 at risk and Rainbow has, therefore, updated its guidance to indicate that the DFS will be completed during full-year 2025.

Further, Rainbow plans to provide updated project economics in a report to be published in the fourth quarter of this year. The report will evaluate the various product options currently available as revenue generators for the project.

“The supply chain for REE is subject to excessive vulnerabilities due to the dominance of China, who are increasingly demonstrating their ability to restrict access to speciality metals.

“The geopolitical risks have never been greater and we foresee that Phalaborwa can play an important part in the development of an independent and ethical supply chain of all four critical magnet REE,” says Bennett.

In addition to producing NdPr, the Phalaborwa project is also expected to produce dysprosium and terbium.

Bennett points out that Rainbow also expects that its “innovative” processing technology to recover critical REE from phosphogypsum will, in the longer term, allow the company to access a much larger addressable market.

To this end, it is currently evaluating approaches for strategic partnership opportunities in Saudi Arabia, Canada and India, along with a memorandum of understanding signed with Mosaic Company for the Uberaba project, in Brazil, and Rainbow’s partnership with phosphate products producer OCP and the Mohammed VI Polytechnic University, in Morocco.