Rainbow and Mosaic Commence Uberaba PFS

Rainbow and Mosaic launch Uberaba PFS, targeting US$916M NPV and 45% IRR by 2027.

What the company is saying

Rainbow Rare Earths and The Mosaic Company have formally started a Pre-Feasibility Study for the Uberaba rare earths project in Brazil, highlighting this as a major step under their Joint Development Agreement. The announcement emphasizes modeled project economics from the March Economic Assessment, specifically a post-tax NPV10 of US$916 million, a post-tax IRR of 45%, and average annual EBITDA of US$217 million over a 30-year mine life, all based on spot rare earth prices as of March 2026. The company stresses the technical credibility of the project by naming SRK Consulting as the group preparing the maiden JORC-compliant Mineral Resource Estimate. Mosaic is shipping approximately 6 tonnes of phosphogypsum feedstock to Rainbow's South African laboratory for further test work, reinforcing the ongoing technical collaboration. The narrative positions Uberaba as a strategic, scalable, and potentially low-cost rare earths opportunity, leveraging proprietary IP from Rainbow's Phalaborwa project. CEO George Bennett is quoted to reinforce confidence in the project's strategic importance and the company's technical approach.

What the data suggests

The disclosed figures are projections from the Uberaba Economic Assessment, not realised results. The project targets an annual throughput of approximately 2.7 million tonnes of phosphogypsum over an initial 30-year life, with a head grade of about 5,100 ppm TREO. Modeled outputs include separated NdPr oxide and SEG+ mixed rare earth carbonate, each at 99.5% purity. The economic model shows a post-tax NPV10 of US$916 million, a post-tax IRR of 45%, average annual EBITDA of US$217 million, and a pay-back period of 1.7 years, all calculated using March 2026 spot rare earth prices. The PFS is scheduled for completion in H2 2027, with no binding funding, offtake, or construction commitments disclosed. The only realised steps are the PFS launch, consultant appointment, and shipment of test feedstock. All production, revenue, and cost benefits remain contingent on future technical and commercial milestones.

Analysis

The announcement is upbeat, highlighting the commencement of a Pre-Feasibility Study (PFS) and referencing strong modeled economics (NPV, IRR, EBITDA) from a prior Economic Assessment. However, the majority of key claims are forward-looking: the PFS itself is only just starting, with completion not expected until H2 2027 (almost 2 years away), and all production, revenue, and cost benefits are contingent on future milestones. The large-scale processing plant and 30-year project life underscore significant capital intensity, but there is no disclosure of committed funding, binding offtake, or construction start. The modeled financials are based on spot pricing and are not realised results. Language such as 'potential to deliver near-term REE production' and 'lowest-cost quartile' is aspirational, not yet substantiated by operational data. The only realised milestones are the PFS initiation, consultant appointment, and shipment of test feedstock. Thus, the narrative inflates the signal relative to actual progress.

Risk flags

• ●Execution risk is high, as the project is only at the PFS stage with completion not due until H2 2027. Delays or negative study outcomes could materially affect project viability and timelines.
• ●Financial projections are based on spot rare earth prices from March 2026, which may not hold by the time of actual production. Market volatility could significantly impact NPV, IRR, and EBITDA outcomes.
• ●No binding funding, offtake agreements, or construction commitments have been disclosed, leaving the project exposed to financing and commercialisation risk.
• ●The technical process relies on proprietary IP from the Phalaborwa project, but replication at Uberaba is unproven at scale. Process or metallurgical challenges could arise during piloting or scale-up.
• ●Permitting, environmental, and regulatory hurdles in Brazil could delay or derail project development, especially given the project's scale and 30-year planned life.

Bottom line

This announcement signals the start of formal technical studies for the Uberaba rare earths project, with Rainbow and Mosaic aiming to replicate a process proven at Phalaborwa and targeting strong modeled economics: US$916 million NPV, 45% IRR, and US$217 million average annual EBITDA over 30 years. All figures are projections based on spot pricing and are not yet underpinned by binding offtake, funding, or construction decisions. The PFS is not due until the second half of 2027, so any investment case is long-dated and subject to significant execution, market, and technical risks. Investors should treat the modeled returns as indicative, not guaranteed, and focus on future updates regarding study progress, funding, and commercial agreements. The most important takeaway is that Uberaba remains a conceptual opportunity, with real value contingent on successful technical de-risking and commercialisation over the next several years.

Announcement summary

(LSE:RBW) Rainbow Rare Earths Limited and The Mosaic Company (NYSE:MOS) have commenced a Pre-Feasibility Study (PFS) for the Uberaba project in Brazil under their Joint Development Agreement. SRK Consulting Ltd has been appointed to prepare a maiden JORC-compliant Mineral Resource Estimate (MRE) for the project. Mosaic is shipping approximately 6 tonnes of phosphogypsum feedstock to Rainbow's laboratory and pilot plant in South Africa for further test work and piloting. The PFS will focus on building a processing plant on-site at Uberaba to process phosphogypsum waste residue at an annual throughput of approximately 2.7 million tonnes per annum (Mtpa) over an initial project life of 30 years, with an originally modelled head grade of approximately 5,100 ppm TREO. The PFS is expected to be completed by H2 2027. The project will produce separated neodymium and praseodymium (NdPr) oxide and a samarium, europium and gadolinium plus (SEG+) mixed RE carbonate, each at 99.5% purity. The Uberaba Economic Assessment (EA) announced in March demonstrated a post-tax NPV10 of US$916 million, a post-tax IRR of 45%, average EBITDA of US$217 million per annum over a 30-year life-of-mine, and a pay-back of 1.7 years, using spot rare earth pricing reported by Argus Media Limited at March 2026. Rainbow has leveraged proprietary IP developed for the Phalaborwa project to establish a flowsheet for Uberaba, with the potential to replicate and apply the Phalaborwa process at other phosphogypsum projects. Uberaba is strategically situated in Brazil, a crucial hub for rare earths supply chain independence and the focus of extensive U.S. Government support for the industry, and has the potential to deliver near-term REE production in the lowest-cost quartile.

Disagree with this article?