Update on Laboratory Test Work in South Africa

3 June 2025

Rainbow Rare Earths Limited

("Rainbow" or "the Company")

LSE: RBW

Update on the Laboratory Test Work in South Africa

and the Trade-off Studies to optimise costs at Phalaborwa

·    Following the Interim Study released in December 2024, Rainbow indicated to the market that the Company would be focused on:

o  Undertaking trade-off studies for the primary leaching circuit, which represents ca. 80% of the expected total cost base for the project, to minimise both operating and capital costs

o   Maximising rare earth recovery and impurity rejection in the initial continuous ion exchange ("CIX") circuit

o    Definition of the optimal path to purification of the mixed rare earth feed ahead of final separation

·    The Rainbow in-house laboratory in Johannesburg has now been running for ca. three months and work is progressing well

·    The cost of carrying out this work in-house is significantly lower than the equivalent cost in a third-party lab, also allowing for the faster turnaround of assays and bench scale results

·    Rainbow will use the results of the trade-off studies and test work to provide the optimal process flowsheet in order to finalise the definitive feasibility study ("DFS")

News Announcement

Rainbow Rare Earths is pleased to announce an update on the Company's laboratory test work and the trade-off studies that are being evaluated to further optimise capital and operating costs for the Phalaborwa project.  

George Bennett, CEO, commented: "We are very proud of the laboratory we have built in Johannesburg which incorporates state-of-the-art equipment that enables the performance of test work across the full Phalaborwa processing flow sheet.  Establishing our own in-house facility allows for the execution and analysis of this critical optimisation and separation test work at an accelerated rate and at a much lower cost than using third party facilities. We have identified the key priority focus areas for the test work, and I look forward to announcing the results of the various stages of the ongoing programme as these become available.

This optimisation work will further enhance the economic resilience of a project that is already deemed to be one of the highest margin REE projects in development today, according to Argus Media.  At a time when the world urgently needs diversified REE supply, Phalaborwa is poised to be a strategic source of all four magnet rare earths."

Laboratory Update

The Rainbow laboratory in Johannesburg has now been in operation for ca. three months and is equipped with state-of-the-art technology that allows for the performance of leaching, ion exchange, precipitation and separation test work across the full Phalaborwa processing flowsheet.

Most importantly, the laboratory features a cutting-edge ICP-MS (Inductively Coupled Plasma - Mass Spectrometer) for analysis of samples taken from test work, which enables the immediate assay of grades ranging from low parts per billion to high purity to be reported internally. This level of accuracy is vital for the evaluation of the Company's separation test work. The laboratory is equipped to automate test work where possible to ensure accurate and rapid results.

Turnaround times for these tests are therefore considerably faster than the typical 72 hours to three weeks experienced when using external providers. This rapid turnaround ensures that test work can be continuously progressed in a targeted and informed manner based on previous test results.

By carrying out the test and assay work at in-house facilities, the Company has delivered significant savings compared to using third party providers and expects to pay back the modest cost of building the laboratory within a few months.

Following the Interim Study released in December 2024, test work and associated work has been focused on:

1.    Undertaking trade-off studies for the leaching circuit to minimise both operating and capital costs

2.    Maximising rare earth recovery and impurity rejection via CIX

3.    Definition of the optimal path to purification of the mixed rare earth feed ahead of final separation

Further information on these key work programmes is as follows:

1.    Trade-off studies to optimise the leach circuit

The leach circuit is estimated to represent ca. 80% of the Phalaborwa flowsheet and therefore offers the best opportunities for cost optimisation. While Phalaborwa's capital and operating costs are already considerably lower than the majority of the rare earth peer group, the work that was done during the project's Interim Study identified areas where further test work and trade-off studies have potential to reduce costs, making Phalaborwa even more resilient in terms of its economics.

The key optimisation opportunities identified, which are expected to deliver savings in power, reagent, labour and capital costs, are:

·    Replacing the three-stage 30˚c leaching circuit with a two-stage higher temperature leach circuit with reduced residence times

·    Mechanical vs hydraulic reclamation of the phosphogypsum

·    On-site sulphuric acid plant vs acid supplied from a third party

·    The cost and supply resilience of third-party green energy vs Eskom power supply

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.

2.    Maximising rare earth recovery and impurity rejection

The extensive piloting work carried out to date has established that the production of a high grade, low impurity feed stream to the separation process is key to achieving separated rare earth oxides of the desired purity level.

The development of the leaching process has successfully managed impurity build-up in the leach solution to prevent the impact of impurities on the extraction of rare earths from the phosphogypsum. The Company has seen the benefits in using CIX as the primary process to recover the rare earths from the leach solution, which is expected to successfully reduce impurities in an efficient and cost-effective way, producing a low impurity feed stream for separation.

A number of resins and eluants have been tested at bench scale to select the configurations of the primary IX rare earth recovery circuit to be used for pilot scale test work.

3.    Definition of the optimal path to final separation

Early testing is underway looking at key impurity levels from the primary CIX and proven rejection techniques ahead of separation. For the separation test work it is important that the leaching and recovery options are finalised to ensure a representative feed. Ahead of the final purification results, early ion chromatography separation tests are underway to establish rare earth performance under various configurations. These tests are expected to accelerate the development of the final recipe once the purification steps are complete.

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