Rainbow Rare Earths has announced the launch of an Economic Assessment (EA) in partnership with agricultural giant Mosaic to explore the commercial potential of extracting rare earth elements (REEs) from phosphogypsum waste at the Uberaba phosphoric acid plant in Brazil.

The joint assessment represents a major milestone in the collaboration between Rainbow and Mosaic, one of the world’s largest producers of phosphate and potash-based crop nutrients. The Uberaba operation, located in the state of Minas Gerais, processes phosphoric acid and produces substantial quantities of phosphogypsum — a by-product now emerging as a promising unconventional source of rare earths.

The proposed project would process approximately 4.3 million tonnes per annum (Mtpa) of phosphogypsum — double the scale of Rainbow’s flagship Phalaborwa project in South Africa. Early test work, conducted by Mosaic with support from Rainbow, has confirmed the presence of rare earth oxides (TREO) averaging 0.58 per cent. Of this, nearly a quarter comprises neodymium and praseodymium (Nd/Pr), two highly valuable elements critical to permanent magnet production, with economically viable concentrations of dysprosium and terbium also identified.

The EA will use this data to model a potential recovery operation and assess commercial viability. If successful, it would mark a significant step towards industrial-scale REE extraction from secondary sources — an emerging frontier in global critical minerals supply chains.

Rainbow and Mosaic have approved the budget and commenced technical work on the study. The results are expected to inform a potential future partnership agreement to replace the current non-binding memorandum of understanding (MoU).

News in full

We caught up with CEO George Bennett at the 2024 Mining Indaba conference in Cape Town. He provided an update on Rainbow’s operations, but also told us about the many uses of rare earths and why they are so important in the global energy transition.