The Uberaba project in Brazil is the subject of a Joint Project Development Agreement between Rainbow and its owner the Mosaic Company (“Mosaic”)(NYSE: MOS), the world-leading American producer and marketer of concentrated phosphate and potash crop nutrients based in Tampa, Florida. The project is similar to Phalaborwa in that it will entail the processing of phosphogypsum, a “waste” product that is the residue from phosphoric acid production, and will use Rainbow’s intellectual property to economically extract REE.

In March 2026, Rainbow published an Economic Assessment (“EA”) for Uberaba that confirmed the project as a second major opportunity for Rainbow, with the potential to be a long-life, high-margin and near-term producer of both light and heavy REE.

Using Rainbow’s internal 10% discount rate and rare earth pricing reported by Argus Media Limited (Argus) at 5 March 2026, the Uberaba EA post-tax NPV10 is US$916 million, with a post-tax IRR of 45%, average EBITDA of US$217 million per annum over a 30 year life, and a pay-back of 1.7 years.

Where we operate

Key facts

  • 0.51% average grade TREO
  • Nd, Pr, Dy, Tb basket contains all four magnet REEs
  • 24.5% proportion of NdPr within the basket

The Uberaba project is located in the Minas Gerais state of Brazil where Mosaic is currently mining phosphate rock and producing phosphoric acid for use in the fertiliser industry. The EA envisages building a processing plant on-site to process the phosphogypsum waste residue at an annual throughput of ca. 2.7 Mtpa over an initial project life of 30 years. There is excellent potential to extend this life due to the underlying long life of the phosphate feedstock at Uberaba.

The flowsheet that has been defined for the EA uses Rainbow’s background IP developed for the Phalaborwa project, further supported by collaborative test work between Rainbow and Mosaic. The phosphogypsum from the Uberaba phosphoric acid process facility is treated for REE extraction, with the aim of delivering separated NdPr oxide anda SEG+ product that is rich in medium and heavy REE, each at +99.5% purity. The chemically processed and cleaned phosphogypsum stream is then returned to the Mosaic Uberaba process facility.

Rainbow has presented the base case economics on the basis of spot rare earth prices published by Argus on 5 March 2026 assuming 100% payability for a combined NdPr product and 70% payability for the SEG+ product. The NPV is presented at a 10% discount rate, which matches the discount rate used for Rainbow’s Phalaborwa project.

Key findings of the EA at current rare earth pricing:

Base case
Basket price US$/Kg1 128
Post-tax NPV using Rainbow’s internal 10% discount rate US$ million 916
Post-tax NPV using Mosaic’s internal 13.5% discount rate US$ million 609
Post-tax IRR % 45%
Capital Expenditure US$ million 279
Revenue2 US$ million pa 319
Operating Cost US$/Kg1 38
EBITDA US$ million pa 217
NdPr oxide Tonnes pa2 1,971
SEG+, including: Tonnes pa2 659
• Dysprosium (“Dy”) 60
• Terbium (“Tb”) 14
• Yttrium (“Y”) 188
Payback Years 1.7
1. Basket price and operating costs calculated on 100% payability basis for NdPr and SEG+ weighted in-line with the feedstock grade
2. Revenue and production statistics based on steady state throughput excluding ramp up during commissioning phase

Further to the outstanding financial results of the EA, Rainbow and Mosaic have signed a Joint Project Development Agreement to move ahead and carry out a Pre-Feasibility Study (PFS) for Uberaba.

On completion of a positive PFS and a decision to proceed with a Definitive Feasibility Study (DFS), the parties will negotiate Heads of Terms for a joint venture agreement and a shareholders agreement for a jointly held JV company (JVCo) which will be held 51% Mosaic and 49% Rainbow.