Rainbow Rare Earths Ltd (LSE:RBW, OTC:RBWRF, FRA:RR1) told investors that its Uberaba project in Brazil could become a second major rare earths development after signing a project agreement with Mosaic and publishing an economic assessment that valued the project at up to US$916 million on a post-tax NPV10 basis.
"The results of the EA confirm that Uberaba represents a major opportunity to replicate Phalaborwa as an additional high-margin and near-term REE development project, situated in the lowest-cost quartile for the industry," said chief executive George Bennett.
The new study has outlined a 45% post-tax IRR, average annual EBITDA of US$217 million, and a 1.7-year payback, based on Argus rare earth pricing at March 2026. Using a 13.5% discount rate, post-tax NPV was estimated at US$609 million.
Rainbow said Uberaba would process phosphogypsum waste from Mosaic’s existing fertiliser operations in Minas Gerais, with annual throughput of about 2.7 million tonnes over an initial 30-year life.
At steady state, the project is expected to produce 1,971 tonnes per year of neodymium-praseodymium oxide and 659 tonnes per year of SEG+ product, with annual revenue of US$319 million and operating costs of US$38 per kilogram. Initial capital expenditure was put at US$279 million.
Rainbow and Mosaic will now move into a pre-feasibility study. If that is positive and the partners decide to proceed to definitive feasibility, they intend to form a joint venture owned 51% by Mosaic and 49% by Rainbow. The companies are targeting initial production in 2030.
George Bennett added: "We are looking forward to applying all the learnings that have been made in the development of Phalaborwa's flowsheet, which provide the opportunity to develop Uberaba on a faster timescale... We have enjoyed working alongside our partner Mosaic, who has provided important technical and operational expertise, as well as a willingness to innovate and make quick progress, and we are delighted to have signed the Joint Project Development Agreement with them to take the project forward."