Highlights
- Up to 91% Rubidium recovery achieved during Phase 2 ECU Mineral Recovery Research Centre (MRRC) processing program
- Rubidium chloride product successfully produced via direct rubidium extraction process as well as Lithium as a by-product from R&D test work
- Further testing underway to enhance purification and optimisation processes
- Results underpin grant applications for development of construction of a pilot-scale plant in 2025
- Engineering Scoping Studies to commence focussing on high level techno-economic analysisof destructive rubidium process
- Patent applications planned to protect EMC owned intellectual property rights
- Investigations into grant funding are ongoing as Rubidium is a critical material used in high-tech applications including defence, military, aerospace and communications
Everest Metals Corporation Ltd (ASX: EMC) (“EMC” or “the Company”)is pleased to announce it has successfully produced its first rubidium product from the Mt Edon Critical Mineral Project in Western Australia, with laboratory testing achieving a recovery rate of up to 91% (Figure 1).
EMC’s Executive Chairman and CEO Mark Caruso commented:
“We are moving swiftly to determine the most efficient and economically viable process to recover value from the Mt Edon Critical Mineral Project. Our ongoing research and development efforts are focused on evaluating various production processes to determine optimal rubidium recovery and purity outcomes.
The consistent repeatability of conversion under a variety of test conditions demonstrates the strength of our key design parameters, reinforcing our confidence that we will be able to produce high value rubidium components from Mt Edon material. We are pleased to report outstanding recovery rates of up to 91% rubidium, and extraction of lithium as a potential by-product underscoring the effectiveness of our Company’s processes at Mt Edon.”
Rubidium Extraction R&D Project Background
On 26 February 2024, Edith Cowan University (“ECU”) and EMC executed a Research Agreement (“Agreement”) for studies in relation to the extraction of rubidium from Mt Edon pegmatite[1]. The research activities undertaken at ECU’s Mineral Recovery Research Centre (“MRRC”) were estimated to take place over a 12-month period.
The first stage of the collaboration between EMC and MRRC involved a small-scale laboratory demonstration of all the processing steps in the recovery of rubidium. The Direct Rubidium Extraction (“DRE”) test work and studies utilised advanced processes such as ion exchange. The project focuses on extracting the rubidium from Mt Edon ore using a Direct Rubidium Extraction technology.
Due to the increasing need for sustainable and environmentally friendly extraction processes, these studies aim to develop a state-of-the-art extraction technique that maximise the recovery of rubidium and lithium. By selecting suitable cations (positively charged ions) and optimising operating conditions, the project aims to achieve maximum rubidium extraction by utilising a cost effective and environmentally friendly method. This approach leverages cutting-edge technologies, innovative methodologies, and industry best practices to ensure a sustainable and profitable extraction process. The process encompasses purification and refining, ultimately leading to the conversion into a final product such as rubidium salts and metal.
The Company’s investment in this project qualifies for the Federal Government Research and Development (“R&D”) Tax Incentive program and under the Agreement any Intellectual Property (“IP”) rights deriving from the project will be owned by EMC.
As part of this study, critical assessment of the feasibility and potential enhancements of the DRE method is ongoing. This will allow EMC and ECU to jointly apply for the Cooperative Research Centres Projects (“CRC-P”) Grants, Australian Research Council’s (“ARC”) Linkage Program, Australia’s Economic Accelerator (“AEA”), etc. to scale up the process technology.
Various test work was conducted by ECU’s MRRC with results demonstrating acceptable levels of both rubidium and lithium in the leach liquor. The initial results reported by Everest in July 2024 demonstrated a technically viable rubidium recovery rate of up to 85% recovery using the Direct Extraction method[2]. To extract rubidium and lithium, two process methods were used – non-destructive and destructive.
In the non-destructive method, the structure of muscovite remained unchanged. Two sets of acidic and non-acidic experiments were performed, and X-Ray diffraction analysis (XRD) was conducted on the samples before and after the tests to explore the structure of the solid powder and Inductively Coupled Plasma (“ICP”) for assay. In non-acidic tests, low acid concentrations of the sample were prepared to enhance rubidium extraction. Multiple tests were performed with the majority of the experiments repeated two or more times. Five different chemical compounds were utilised during the non-destructive set of tests. As these experiments were conducted without acid, the effects of reaction time and temperature on the sample were also investigated for the sake of optimisation.
During the destructive process method, the muscovite structure was deteriorated to gain the maximum extraction of rubidium. Several tests were conducted during this stage, and the results verified to ensure the same consistent and reliable outcomes. The maximum rubidium extraction achieved in this stage demonstrated the desired repeatability within a range of 75±10%[3].
The Company recently appointed Jon Starink as senior technical consultant to lead the development of the rubidium processing and marketing strategy for the Mt Edon Critical Minerals Project. Mr Starink’s appointment coincides with scale-up pilot plant processing and future developments on which EMC and ECU plan to collaborate[4].
Phase 2 Test Work Process
During phase 2, two critical processes were examined: refinement and conversion. The refinement process utilised a specific chemical as an adsorbent for Direct Rubidium Extraction (“DRE”), while another chemical was employed as a precipitation inducing agent. This dual approach allowed for effective separation of rubidium from the Mt Edon Ore.
Figure 1: First vial of high purity rubidium chloride (RbCl) product
In the conversion stage, the DRE process yielded Rubidium Chloride (RbCl) as the primary product, eliminating the need for additional conversion steps (Figure 1). However, when a precipitation agent was used, the resulting rubidium salt product may require further conversion, which will be addressed in the final project milestone.
This phase of project represented the core experimental work of the project, focusing on process optimisation through systematic investigation of critical parameters. The destructive process was extensively studied, with particular attention paid to roasting conditions, and leaching parameters. Various operational conditions were examined, including temperature effects, duration of treatment, and the impact of different chemical types.
Parallel investigations of acid leaching were conducted, exploring temperature influences, and the effects of different acid types and concentrations. Throughout these experiments, samples were systematically collected for comprehensive analysis. The analytical phase employed multiple characterisation techniques to evaluate process effectiveness.
Inductively Coupled Plasma Mass Spectrometry (“ICP-MS”) and Inductively Coupled Plasma Optical Emission Spectroscopy (“ICP”) analyses were conducted to determine rubidium and lithium concentrations and monitor the presence of other elements. Structural changes in the hard rock during extraction were monitored using XRD, while Scanning Electron Microscopy (“SEM”) and Energy-Dispersive X-ray Spectroscopy (“EDS”) analyses provided detailed information about morphological changes and elemental distribution. Similar analytical approaches were applied to study the adsorbent structure during the purification process. In next phase, process reliability and accuracy were ensured through repeated testing at maximum rubidium concentrations.
This systematic approach to validation has provided a robust foundation for process optimisation and scale-up considerations. While some aspects of the project, such as ore beneficiation, remain to be completed in the final milestone, the results obtained thus far demonstrate significant progress toward developing an economically viable and environmentally friendly extraction process. Throughout these experiments, samples were systematically collected for comprehensive analysis. The analytical phase employed multiple characterisation techniques to evaluate process effectiveness.
The destruction process was extensively studied using hard rock pegmatite samples with rubidium content between 0.25–0.35% Rb2O and lithium grade varying 0.08-0.11% Li2O. Through comprehensive experimentation and validation involving 47 samples analysed via ICP-MS at MRRC and 14 at the ALS laboratory, optimal conditions were established.
To determine the optimal conditions for rubidium extraction, several key parameters were investigated, including the effects of temperature, type and concentration of acid and chemicals, process type, and extraction time. The significant colour gradient, ranging from clear to yellow to orange in the samples, strongly indicates the effects of optimised conditions. The extraction efficiency varies with adjustments to test conditions, as demonstrated by the progressively intensifying colours across the samples, systematically arranged to show the advancement of extraction effectiveness (Figure 2).
Figure 2: Visual changes during acid leaching process optimisation. The image illustrates the changes in sample colours (from left to right) resulting from the optimisation of various parameters during the acid leaching process, highlighting the effect of extracting different oxidation states of elements on the colour of the samples.
The optimisation and validation of rubidium and lithium extraction processes from the Mt Edon hard rock samples (pegmatite) has been systematically investigated through three distinct approaches: destruction process, acid leaching, and purification methods. Each method demonstrated varying degrees of effectiveness and applicability for industrial-scale rubidium recovery.
The purification phase employed two approaches: ion exchange-based extraction and precipitation-based selective precipitation. The results demonstrated exceptional efficiency with 91% overall recovery of rubidium for synthesised brine. Of note, 92 g/t lithium was produced as the by-product.
In Figure 3, the SEM images reveal the morphological characteristics of ion exchanger before and after rubidium exposure at a scale bar of 5μm. Images a and b (before rubidium exposure) show that the bare ion exchanger possesses a uniform granular structure with spherical-like particles that are well-distributed and exhibit relatively smooth surfaces.
The particles appear to be agglomerated into cluster formations, displaying a homogeneous size distribution. In Images c and d (after rubidium exposure, refer to Figure 3), the surface morphology shows notable changes where the particles become more irregular with visible surface roughness and some apparent cavities.
The particles after adsorption appear to have slightly larger agglomerates with more distinct edges and surface features, suggesting successful interaction and incorporation of rubidium ions within the medium structure. These morphological changes between the pre- and post-exposure samples provide visual evidence supporting the effective recovery of rubidium onto the extractant medium.
A comprehensive process for rubidium extraction and recovery has been developed, providing a systematic outline of each processing stage and material flow. This process showcases an advanced method for selective ion separation and recovery, integrating both primary rubidium extraction and secondary lithium recovery pathways.
The Company is preparing the necessary documentation to file an Australian Provisional Patent Application (“Patent Application”) to protect the Intellectual Property (“IP”) related to the Process. EMC’s primary objective with this filing is the protection of the Company and its shareholders by protecting the unique and efficient processing design developed for advancing the Mt Edon Project toward production.
The patent application will cover a combination of individual physical beneficiation steps and metallurgical processes, all aimed at achieving the specific objectives for preparing the rubidium products.
Figure 3: SEM images of extractant medium before (A and B) and after (C and D) exposure to Rubidium containing samples
Future Activities
Based on the results achieved during phase 2 and the objectives of the projects, EMC is planning the following steps to advance its work for Mt Edon:
- Engineering Scoping Study (ESS)
- A high level inital techno-economic analysis initiated for destruction process, focusing on both capital expenditure (CAPEX) and operational expenditure (OPEX).
- High pressure acid leaching
- Extra plan for rubidium extraction focusing on implementing high pressure acid technology.
- Purification processes
- Ion exchange: Plan to transition tests from a batch mode approach to a bench scale setup. This change will assist to optimise critical process parameters. Ultimately, these optimisations will contribute to the development of a comprehensive and effective purification process for future applications.
- Precipitation: More comprehensive test work to aid with design of an optimised precipitation process. This data will be crucial in identifying and refining key process parameters, such as concentration levels, temperature, and reaction times, to develop an efficient and effective precipitation process that will contribute significantly to the overall purification strategy.
Table 1: Drill Hole Details Contributing to Mt Edon Metallurgical Samples
| Hole_ID | Easting MGA94 | Northing MGA94 | From (m) | To (m) | Height (m) | Total Depth (m) | Dip (degrees) | Azimuth (degrees) |
| MD-50 | 564560 | 6756381 | 84 | 116 | 373 | 131 | -50 | 137 |
| MD-45 | 564555 | 6756439 | 37 | 126 | 375 | 126 | -50 | 70 |
| MD-35 | 564585 | 6756487 | 41 | 51 | 361 | 126 | -50 | 38 |
| MD-48 | 564654 | 6756495 | 66 | 102 | 368 | 72 | -60 | 268 |
| ME23-19 | 564570 | 564570 | 25 | 205 | 370 | 119 | -50 | 270 |
| ME23-07 | 564537 | 564537 | 49 | 89 | 360 | 111 | -60 | 118 |
- Grid is GDA94 – Zone 50
MT EDON PROJECT
Mt Edon Critical Mineral Project is located 5km southwest of Paynes Find, in the Mid-West region of Western Australia, approximately 420km northeast of Perth. Mt Edon has an initial Inferred Mineral Resource (MRE) of 3.6 million tonnes grading 0.22% Rb2O, and 0.07% Li2O (at 0.10% Rb2O cut-off), contains more than 7,900 tonnes of Rb2O (Table 2)[5].
The maiden Inferred MRE includes a high-grade subset of 1.3Mt at 0.33% Rb2O and 0.07% Li2O (at 0.25% Rb2O cut-off) which is nearly 56% of the total contained Rb2O tonnes. This verifies the tier-1 scale and grade of the Mt Edon deposit. The MRE is limited to a strike length of only ~400m within a 1.2km lithium-caesium-tantalum (LCT) pegmatite corridor and a vertical depth of ~140m below surface.
Table 2: Mt Edon Maiden Mineral Resource Estimate (JORC Code 2012)
| Category | Tonnes (Mt) | Rb2O (%) | Contained Rb2O (t) | Li2O (%) | Contained Li2O (t) |
| Inferred | 3.6 | 0.22 | 7,900 | 0.07 | 2,500 |
| Total | 3.6 | 0.22 | 7,900 | 0.07 | 2,500 |
- Mineral Resources are classified and reported in accordance with JORC Code (2012).
- Mineral Resource estimated at a 0.10% Rb2O cut-off.
- Mineral Resource is contained within mining licence M59/714.
- All tabulated data have been rounded.
Multiple geological and geophysical targets exist across the project, which along with the resource modelling that underpins the MRE, form the basis for further exploration and anticipated resource growth. Modelling has shown the mineralisation remains open along strike to the northeast and southwest, providing immediate potential to significantly increase the MRE with follow-up drilling. The Mt Edon resource has outcrop or occurs close to surface and will be amenable to opencut mining, with the information suggesting a low stripping ratio.
Figure 4: Mt Edon mining lease location map, southwest of Paynes Find, Western Australia
RUBIDIUM OVERVIEW
Applications and Importance
Rubidium (Rb) is a critical raw material for various high-tech applications, including the development of new energy conversion technologies and new communication technologies. Key applications include:
- Defence and Military: Night vision imaging, special glass, radiation detectors, photoelectric tubes, radio electronic tubes and military infrared signal lights.
- Aerospace: ion propulsion engines and atomic clocks.
- Communications: Ion cloud communications and fibre optic communications.
- Emerging Energy Power Generation: Materials for magnetohydrodynamic power generation and thermionic power conversion.
- Medical: Sedatives, tranquilisers and medications for treating epilepsy and synthetic alkaline solvents.
- Special Glass: Enhancing glass conductivity, increasing lifespan and stability.
- Industrial Catalysts: Widely used in ammonia synthesis, sulfuric acid synthesis, hydrogenation, oxidation and polymerisation reactions.
- Electronic Devices: Important materials for photovoltaic cells, photoemission tubes, TV camera tubes and photomultiplier tubes.
Researchers have also recently proposed the use of rubidium for chemical storage within hydrogen batteries, expanding the potential market for this critical mineral[6].
Production and Market Trends
Despite the breadth of applications and demand for rubidium and caesium and their hydrides, global production of caesium and rubidium is significantly lower than that of other alkali metals, and the cost per kilogramme is substantially higher than lithium, sodium or potassium.
Due to the gradual depletion of caesium resources, but the continued demand of these industries, a replacement is required, with Rubidium being a suitable candidate. The downstream application fields of Rubidium salts are rapidly growing, enhancing the Company’s market advantage in this sector. As a result, rubidium has been listed as one of the 35 critical minerals by several countries around the globe including USA and Japan.
According to the U.S. Geological Survey (2024)[7], global rubidium resources are relatively scarce, with most resources containing limited Rubidium content. The Rubidium Industry is expected to grow from 4.46(USD Billion) in 2023 to 7.2 (USD Billion) by 2032. The rubidium Market CAGR (growth rate) is expected to be around 5.48% during the forecast period (2024 – 2032)[8].
Several market factors support growth in demand for rubidium and underpin the current price of ~USD1,200/kg[9]. Among these, there is significant global demand for newer and faster electronic products due to the rapid pace of innovation, technology advancement and R&D activities in the electronics industry. This increasing demand for rubidium, coupled with the fact that Rubidium is difficult to source due to extremely limited global production, underpins the extremely high price of rubidium products.
North America holds a significant share of the rubidium market in terms of both market share and revenue. However, like most critical minerals, China maintains control of the market. Commodity analysts believe if more rubidium was produced, the market could grow rapidly and therefore its very small market size can be partially attributed to supply constraints, rather than a lack of demand.
NEXT STEPS
Everest has a clear strategy to continue its development of Mt Edon Critical Mineral Project, with the following steps set for delivery over the coming months:
- Continued discussion with potential commercial customers
- Development of grant application for scale up pilot plant processing, Q1 2025
- Scoping study due for completion in Q2 2025
- Pilot plant design and implementation, Q3 2025
- Phase 2 Resource Drilling, H1 2025
[1] EMC ASX Announcement: EMC To Advance Mt Edon Critical Mineral Project Through Rubidium And Industrial Mica Product Development, dated 27 February 2024
[2] EMC ASX announcement; Successful Recovery of Rubidium from Mt Edon Critical Mineral Project, dated 24 July 2024
[3] EMC ASX announcement; Successful Recovery of Rubidium from Mt Edon Critical Mineral Project, dated 24 July 2024
[4] ASX: EMC announcement; Everest Appointed Senior Technical Consultant To Lead Rubidium Processing And Marketing Strategy, dated 7 November 2024
[5] ASX: EMC announcement; EMC Delivers World-Class Rubidium Resource At Mt Edon Project, WA, dated 21 August 2024
[6] S. Matalucci, May 2024, Researchers propose use of caesium, rubidium for hydrogen batteries, pv-magazine.
[7] U.S. Geological Survey, January 2024, Mineral Commodity Summaries 2024
[8] www.marketresearchfuture.com/reports/rubidium-market-27298
