CIX Test Work shows Very High Purity Separation

1 September 2025

Rainbow Rare Earths Limited

("Rainbow" or "the Company")

LSE: RBW

 CIX Test work in South Africa achieves Very High Purity Separation Feed

·    Rainbow's low-cost process, optimised at its in-house laboratory in Johannesburg, has delivered an exceptionally pure mixed rare earth product utilising continuous ion exchange ("CIX")

·    This purified product delivers a mixed rare earth carbonate (''MREC'') averaging >55% total rare earth oxides ("TREO") across multiple test samples / campaigns, considerably exceeding the rare earth industry's typical refinery specification of >42% TREO

·    The purified mixed REE product compares with the highest grade MREC specifications produced by any REE development/producing project globally

·    This purification is a major step towards separation success as the delivery of a high grade; low impurity feed stream is key to achieving separated rare earth oxides ("REO") of the desired purity

·    The TREO purity of the Rainbow MREC specification after multiple tests is now consistently >93% vs the accepted industry specifications of >90%

·    Modelling, and an updated costing, of the proposed final separation process has now commenced based on this high purity feedstock, significantly advancing the Phalaborwa project

·    Work on the Definitive Feasibility Study ("DFS") for the primary leach flowsheet, which is the process that delivers the MREC and which represents ca. 85-90% of the total project Capex, is progressing well

·    The recent trade-off studies are being incorporated in the DFS and are expected to deliver further savings in both capital and operating expenditure

·    As a low-cost, near-term and responsible source of both light and heavy REE, Phalaborwa can play an important role in the delivery of an independent supply chain for these critical minerals, which are vital to both national security and economic resilience

NEWS ANNOUNCEMENT

Rainbow Rare Earths is pleased to announce successful results from the ongoing test work for the Phalaborwa project in South Africa. This unique project encompasses the recovery and separation of REE from phosphogypsum stacks, a waste product from phosphoric acid production, meaning that many of the costs, risks and long timescales associated with traditional mining projects are eliminated. 

Considerable progress has been made upgrading the MREC to >55% TREO and reducing the pregnant leach solution ("PLS") from 340 m³/hour down to between 7-10 m³/hour feeding the final separation circuit. Rainbow expects to finalise the final stages of the process flowsheet to achieve the 99.5% purity levels in our targeted REE products in the near future.

George Bennett, CEO, commented: "These results represent significant progress for the Phalaborwa project, confirming the potential to become a very low-cost producer of light and heavy REE, and one of the highest margin projects in development globally. They also validate our decision to finalise our flowsheet test work in-house and demonstrate that we have developed the expertise to address REE extraction and separation in a highly efficient manner.

The West is finally recognising the importance of REE, used in permanent magnets vital to the functionality of many of the products that underpin 21^st Century society, as well as to emerging and advanced technologies. A number of recent initiatives by the U.S., Australian and European Governments are aimed at improving the economics of, and supporting the financing for, REE projects to rapidly build out end-to-end rare earth permanent magnet ("REPM") supply chains.

The recent offtake agreement between the US Department of Defense and MP Materials utilising a floor price of US$110/kg NdPr demonstrated industry acceptance of a floor price significantly above current market pricing required to ensure new sources of supply to feed a Westen supply chain. Whilst Rainbow's project is very robust at current REE pricing and is expected to deliver a very positive EBITDA. We are therefore very comfortable with this bench-mark floor price set by MP Materials as it is the same price used for NdPr in Rainbow's updated December 2024 interim economic assessment of Phalaborwa which demonstrated the project would generate ca. US$181 million annual EBITDA once in production."

Test Work Update

As set out in the Phalaborwa Laboratory Update announcement in June 2025, key components of Rainbow's test work at its in-house laboratory in Johannesburg have been to maximise and maintain overall REE recovery at ca. 65%, and achieve impurity rejection via CIX. Delivering a high grade, low impurity feed stream to our final separation process has been highlighted as key to reaching separated rare earth oxides of the desired purity level, and this has been  successfully achieved.

Rainbow is delighted to report the successful culmination of this key workstream, with the MREC produced by the primary leach flowsheet upgraded from ca. 44% TREO (achieved in the original piloting process) to the exceptionally high grade MREC equivalent product announced today of >55% TREO, which is significantly higher than the industry standard MREC specification for delivery to Chinese refineries and compares with the top MREC specifications produced by any REE development/producing project globally.

​

Rainbow's in-house team has developed a purification process combining CIX and precipitation steps, which is a novel combination in REE recovery, demonstrating the unique intellectual property in REE extraction that has been built up by the Company.

The incorporation of CIX has led to a highly efficient process, with the ability to reduce the pregnant leach solution ("PLS") flows from 340 m³/hr feeding the CIX down to +/- 7 -10 m³/hr feeding the final separation circuit. This small flow and a simplified final separation process with only two products is expected to result in modest Capex and Opex for this part of the circuit.

The recovery of REE from the phosphogypsum feed to the mixed REE product has been ca. 65%, in line with recoveries used in the recent interim economic study.

These results have been confirmed further through extensive large-scale "lock-cycle" testing (i.e. a repetitive batch test with solution recycle) used to simulate a continuous circuit, and Rainbow has therefore been able to confirm the design parameters for the commercial scale CIX forming part of the project DFS.  The process that has been developed utilises standard CIX and impurity rejection techniques, used extensively in industry, in an innovative combination thereby providing scalability for Phalaborwa's flowsheet.

Rare Earth Oxide Separation Update

Rainbow's focus is now on finalising the final separation process producing a high purity neodymium and praseodymium ("NdPr") oxide.

In consultation with the industry, the optimal heavy REE product has been established as a SEG+ which will be a mix of medium and heavy REEs including the very high value dysprosium ("Dy") and terbium ("Tb") that forms part of Rainbow's REE basket.

Modelling and costing for the proposed separation process has now commenced based on the successful delivery of the high purity feed noted above.

Incoming off-take enquiries have increased considerably following the Chinese export controls announced, in April 2025, on certain medium and heavy rare earths and the magnets that contain them. These restrictions have caused major disruption to the supply chains for high-performance rare earth permanent magnets, with sectors such as automobile, defense and robotics hit particularly hard. Rainbow continues to progress discussions with interested parties and its profile as a low-cost and near-term producer of both light and heavy REE positions it favorably within the peer group of REE development companies.

Trade-off Studies and DFS Update

A further important work stream for the Company is the trade-off studies to optimise the primary leach circuit, which represents ca. 85% - 90% of the Phalaborwa flowsheet and cost base. These studies are progressing positively and are expected to deliver meaningful savings in power, reagent, labour and capital costs.

The Company intends to use the results of the trade-off studies to provide the market with an update as to the potential impact on capital and operating costs for the project ahead of the DFS publication. Rainbow looks forward to announcing progress on the various stages of the ongoing test work in due course.

The Rainbow Rare Earths Curation Connect showcase can be found here: Curation Connect - Rainbow Rare Earths Showcase or https://app.curationconnect.com/company/Rainbow-Rare-Earths-90903

For further information, please contact:

Notes to Editors:

About Rainbow:

Rainbow Rare Earths aims to be a forerunner in the establishment of an independent and ethical supply chain of the rare earth elements that are driving the green energy transition. It is doing this successfully via pioneering the first commercial recovery of rare earth elements from phosphogypsum that occurs as the by-product of phosphoric acid production.  These projects eliminate the cost and risk of typical rare earth projects, which involve mining and the production of a rare earth concentrate that must be chemically cracked to form a mixed rare earth carbonate before further downstream processing. As such, Rainbow's projects can be brought into production quicker and at a lower cost than traditional hard rock mining projects.

The Company is focused on the development of the Phalaborwa Project in South Africa and the earlier stage Uberaba Project in Brazil. Rainbow's process will deliver separated rare earth oxides through a single hydrometallurgical plant on site, with a focus on the recovery of neodymium, praseodymium, dysprosium and terbium. These are critical components of the high-performance permanent magnets used in electric vehicles, wind turbines, defence and exciting new markets such as robotics and advanced air mobility.

The Phalaborwa updated interim economic study released in December 2024 has confirmed strong base line economics for the project, which has a base case NPV₁₀ of US$611 million. Given Phalaborwa is a chemical processing operation, with its resource sitting at surface in a chemically cracked form, it has a much lower operating cost than traditional rare earth mining projects, and it is therefore estimated to be the highest margin rare earth project in development today outside of China.

More information is available at www.rainbowrareearths.com and www.curationconnect.com