Rainbow Rare Earths Ltd (LSE:RBW, OTC:RBWRF, FRA:RR1) says it has significantly simplified the process flow sheet for its phosphogypsum rare earths recovery project, a move expected to reduce costs and improve plant operability ahead of the definitive feasibility study.
Chief executive George Bennett and technical director Dave Dodd joined Proactive to discuss the technical breakthroughs behind the redesign, the remaining DFS work and the project's potential production of high-purity NdPr and heavy rare earth products.
Watch the full interview below and read the transcript underneath.
Proactive: I'm joined by Rainbow Rare Earths Ltd (LSE:RBW, OTC:RBWRF) CEO George Bennett as well as technical director Dave Dodd. Gents, very good to speak with you. George, looking very smart today, are you going somewhere?
George Bennett: Yes, I've been invited by the U.S. Embassy in Pretoria to celebrate the Fourth of July with them. Rainbow has a very close relationship with the U.S. government, hence my invitation by the embassy in Pretoria today.
Proactive: David, turning to today's news, you've simplified the flow sheet quite dramatically. What's the biggest technical breakthrough that gave you the confidence to do that?
Dave Dodd: The breakthrough came from understanding how to control the purity of the leach solution from phosphogypsum, particularly the fluorine present in the phosphogypsum stacks. Previously we had a weak acid leach and fluoride recovery circuit ahead of the rare earth leach, but we've established that we can control fluorine simply by adding silica, which complexes with the fluorine so it doesn't affect the rare earth leach. That has allowed us to eliminate a significant part of the process.
We've also introduced continuous ion exchange (CIX) for the primary recovery of rare earths from the leach solution. This replaces a much more complicated process involving fluorine precipitation, acid baking and water leaching. Those two changes have greatly simplified our flow sheet.
Proactive: George, from an investor's perspective, what does the simpler flow sheet actually mean? Lower costs, lower risk or a faster route to production?
George Bennett: The first two are the key benefits. We believe these optimisations have reduced both capital expenditure and operating costs, helping to keep capital within the figures previously communicated to the market in our December 2024 update.
Just as importantly, the plant is now much more operable from both an HSE and operational perspective. Rare earth processing plants are well known for their complexity, and there are very few operating in the Western world. We believe these optimisations have simplified our flow sheet, improving operability, reducing execution risk and helping ensure we achieve both the planned throughput and targeted rare earth recovery from the phosphogypsum.
Proactive: Dave, the project is recovering rare earths from a waste product rather than mining fresh ore. What have been the biggest technical challenges in making that work at commercial scale?
Dave Dodd: One of the keys has been developing a process that uses standard, proven industry technologies, even though we've combined them in a different way. That makes scaling the process relatively straightforward.
The biggest technical challenges have been understanding acid behaviour during the leaching process and managing impurities, particularly calcium. Because we're processing gypsum, which is calcium sulphate, the system is always calcium saturated. Understanding and controlling calcium behaviour has been critical, and we believe we've now developed a strong understanding of those aspects.
Proactive: George, with around three-quarters of the process now locked in, what's left to prove before investors can look forward to the completed DFS?
George Bennett: There's nothing fundamentally left to prove because we're using standard downstream solvent extraction. The remaining work focuses on optimising the interface between the eluate from the Continuous Ion Exchange circuit and the solvent extraction circuit, ensuring impurity levels are exactly where they need to be.
The solvent extraction circuit will produce separated NdPr at more than 99.5% purity, together with our heavy rare earth concentrate. That product contains approximately 60 tonnes per annum of dysprosium, 20 tonnes per annum of terbium and around 130 tonnes per annum of yttrium, all of which are highly sought-after heavy rare earths.
Proactive: George, David, thanks for the update. We look forward to hearing more about your progress. George, enjoy the Fourth of July celebrations.
