KEY POINTS
- Rainbow Rare Earths has started a PFS for the Uberaba project in Brazil with Mosaic, following a $916-million post-tax NPV economic assessment.
- The project aims to process about 2.7-million tonnes of phosphogypsum waste annually to produce high-purity rare earth products over an initial 30-year life.
- SRK Consulting will prepare the JORC-compliant mineral resource estimate, while further testwork will assess the application of Rainbow’s Phalaborwa technology at Uberaba.
London-listed Rainbow Rare Earths has started a prefeasibility study (PFS) for its Uberaba rare earths project in Minas Gerais, Brazil, in partnership with US-listed Mosaic Company.
The decision follows a positive economic assessment completed in March, which identified Uberaba as a potentially major development opportunity for Rainbow. The company has now moved ahead with detailed technical and economic work aimed at determining the project’s development requirements and commercial viability.
Rainbow has appointed SRK Consulting as the first major technical consultant for the PFS.
SRK will prepare a mineral resource estimate (MRE) that will comply with the Joint Ore Reserves Committee (JORC) reporting standard. Rainbow expects to appoint additional specialist consultants as the study progresses.
The resource estimate will form an important part of the project’s technical foundation, helping to establish the scale and quality of the rare earths resource available for potential development.
Uberaba is located in Minas Gerais, where Mosaic already operates phosphate mining and phosphoric acid production facilities serving Brazil’s fertiliser industry.
Rather than developing a conventional rare earths mine, the project is designed around the processing of phosphogypsum, a waste residue generated from phosphate production.
The proposed processing plant would handle approximately 2.7-million tonnes of phosphogypsum a year over an initial 30-year project life.
The material was originally modelled to contain an average head grade of about 5 100 parts per million total rare earth oxides.
Rainbow believes the project could potentially operate for longer than the initial 30-year period because of the long-term availability of phosphate feedstock at Mosaic’s Uberaba operations.
Rainbow Adapts Phalaborwa Technology
A key component of the project is Rainbow’s proprietary technology.
The company has used intellectual property developed for its Phalaborwa rare earths project in South Africa to establish a processing flowsheet for Uberaba.
Additional testwork carried out by Rainbow and Mosaic has also indicated that the processing approach developed at Phalaborwa could potentially be replicated at other phosphogypsum projects.
Mosaic is sending an additional approximately six tonnes of phosphogypsum feedstock to Rainbow’s laboratory and pilot plant in South Africa for further testing and piloting.
The work is intended to further validate the proposed processing route and support the technical studies required for the PFS.
If developed, Uberaba is expected to produce separated neodymium and praseodymium oxide, as well as a mixed rare earth carbonate containing samarium, europium and gadolinium.
The products are expected to achieve purity levels of 99.5%.
The production of these rare earth elements could position Uberaba to supply materials used in high-value applications, including technologies that depend on permanent magnets and other advanced industrial components.
The March economic assessment highlighted significant financial potential for Uberaba.
Using spot rare earth prices reported by Argus Media at the time, the project was estimated to have:
- A post-tax net present value of $916-million.
- A post-tax internal rate of return of 45%.
- Average annual earnings before interest, taxes, depreciation and amortisation of $217-million over 30 years.
- An estimated payback period of just 1.7 years.
Rainbow said the positive results provided the basis for progressing to the more detailed PFS.
The PFS follows the signing of a joint development agreement between Rainbow and Mosaic, strengthening cooperation between the companies.
Rainbow CEO George Bennett said the company was pleased to continue working with Mosaic and to begin the PFS alongside the appointment of SRK Consulting for the JORC-compliant resource estimate.
Bennett said Uberaba could demonstrate the potential to apply Rainbow’s proprietary technology beyond the Phalaborwa project and to other phosphogypsum-based rare earths developments.
Rainbow also views Uberaba’s location in Brazil as strategically important as countries seek to strengthen rare earths supply chains.
Brazil has emerged as an increasingly important destination for investment in critical minerals, while efforts by the US government to support alternative rare earths supply chains have increased interest in projects outside the dominant global production centres.
Rainbow believes Uberaba could potentially become a relatively low-cost source of rare earths and provide an opportunity for the company to build on the technical experience gained through Phalaborwa.
