Just before the Covid-19 pandemic took hold, South African mining veteran George Bennett was offered the opportunity to bid for two waste piles of gypsum, left over from decades of phosphate mining in a small town near the Mozambique border.
Bennett built more than 20 mining projects over his career, but this one really caught his attention. Analysis of samples he took showed that those waste stacks held a treasure trove—high concentrations of the rare-earth minerals needed to make the permanent magnets used to power offshore wind turbines and electric vehicles.
Rare-earth minerals aren’t actually that rare, but it is unusual to find them in sufficiently high concentrations that would make mining them economical. Having a massive pile of them above ground is even rarer. And new sources are highly valuable because China currently controls most of the extraction and refining of rare earths—a dominance that it is looking to maintain through a ban on the export of rare-earth processing technologies, which it introduced in December.
Rainbow Rare Earths could be a significant non-Chinese source of crucial energy-transition materials, according to Bennett, the company’s chief executive. The company, which was listed in London in 2017, expects to generate a net present value of more than $1 billion from those two South African waste piles, he said.
“There are a lot of rare earth projects…[but] Rainbow is unique in the economics and the environment and carbon footprint associated with the [South African] project. We feel it can be one of the biggest, lowest cost, producers of rare earth oxides in the world,” said Brian Menell, CEO of Techmet, a U.S. government-backed critical-minerals investment company that recently invested $50 million in Rainbow.
Mining is hugely expensive, highly political and can take years to get off the ground, particularly as governments change their policy on mining across election cycles.
Rainbow has been through those struggles. Its mining project in Burundi had been producing rare earths and it had been selling them to Chinese buyers since 2017. Those operations were suspended in 2021 when the local government halted all mining activity in the country to renegotiate the mining code and royalties, according to Bennett.
Fortunately for Rainbow, its Phalaborwa project in South Africa won’t actually involve any digging. The two waste piles of phosphogypsum are above ground and have already been “cracked”—a process where the mined material is crushed and further processed with heat and acid—increasing the rare-earth concentration and thereby reducing the processing that Rainbow needs to do.
“We’ve got no mining cost, no crushing, no milling, no flotation. I saw the advantages to lead to a low capital intensity and low operating cost environment project,” Bennett said. The aim is to start processing from 2026, he said, with an expectation that the project will have about 14 years of productive life.
“Their costs should be competitive in theory as they do not have to do mining,” said Yuen Low, mining analyst at Liberum. He added that Rainbow could create additional value by processing its products further.
Currently, Rainbow’s pilot trials have produced a low value mix of rare earths—known as a rare-earth carbonate—that has to be separated further into the individual minerals used in the making of permanent magnets.
However, Rainbow is now working with K-Tech, a Lakeland, Fla.-based chemical technology firm, on a novel approach to processing the rare earths further into more valuable rare-earth oxides. It is testing out a faster, more environmentally friendly way, known as continuous-ion chromatography, which has been used in photography. Bennett hopes to start producing rare-earth oxides with K-Tech on a trial basis by the end of March.
Rainbow is also developing another, larger site in Brazil. In July, it signed a deal with Tampa, Fla.-fertilizer producer The Mosaic Company for an almost identical phosphogypsum stack in the Uberaba area of Minas Gerais. “Uberaba could be significantly bigger and have a much longer life,” Liberum’s Low said. Rainbow is also working with Morocco’s OCP, the world’s largest phosphate miner, to see if its waste residue could also be viable.
According to analysts, there are very few phosphogypsum sites in the world because it is essentially a waste product of some large-scale phosphate mines. Rainbow is “entirely unique” as a listed company making efforts to recover significant rare earths from gypsum waste sites, according to Christopher Ecclestone, mining strategist at Hallgarten & Co.
Rainbow’s relatively low production costs could give it a competitive advantage over western rivals, according to Bennett.
Shares in competitors MP Materials and Lynas Rare Earths are down 40% and 26%, respectively, over the past year, as rare-earth prices have been hit by falling demand and rising Chinese output. For example, rare earth neodymium oxide—used in permanent magnets—is down 70% since February 2022. There is debate about whether prices have bottomed out, but there is broad consensus that demand for rare-earth oxides will rise. Commodity data firm Argus Media forecasts a 40% rise from current levels over the next decade.
“In the long-term, we would expect prices to recover and go up because global demand will climb amid the energy transition, but in the near-term the mood is still bearish,” said Ellie Saklatvala, head of nonferrous metal pricing at Argus Media.
“Price volatility is by far one of the biggest risk factors for any emerging rare earths supplier—they have very little visibility on their future earnings and margins, which also then deters funding.”