Everest Metals has advanced its Mt Edon rubidium project towards pilot plant development after batch testing delivered recovery of up to 90% and cut leaching water use by 60%. The scale-up remains unfinished, with continuous rotary-kiln trials producing lower and variable recovery of 50% to 60%.
- Up to 90% rubidium recovery in batch roasting and water leaching
- Leaching liquid-to-solids ratio reduced from 10:1 to 4:1
- Potassium-to-rubidium ratio reduced to approximately 1.5 to 2:1 over 20 cycles
- Continuous rotary-kiln trials delivered variable 50% to 60% recovery
- Pilot plant development now moves into engineering, funding and scale-up work
Batch Testing Clears a Path Towards Pilot Development
Everest Metals Corporation Ltd (ASX:EMC) is moving its Mt Edon rubidium project towards pilot plant development after bench-scale work achieved up to 90% rubidium recovery through batch roasting and water leaching. The results also reduced the liquid-to-solids ratio from 10:1 to 4:1, allowing leaching at room temperature and reducing the amount of water and heating required.
The company said the work, carried out with Edith Cowan University’s Mineral Recovery Research Centre under the MRIWA METS Innovation Program and AEA Ignite program, has advanced several parts of the proposed processing route. That route combines roasting, leaching, concentration and purification, rather than relying on the extraction result alone.
Rotary-Kiln Scale-Up Exposes the Main Technical Hurdle
The encouraging batch results have not yet translated cleanly to continuous processing. Initial rotary-kiln trials processed about 60 kilograms of ore and reagents but returned rubidium extraction of approximately 50% to 60%, with significant variation between tests.
ECU attributed the weaker performance to material-handling problems, including salt melting near the kiln entrance that restricted movement through the equipment. Feed and material-flow modifications are now planned, but further testing will be needed to show whether the continuous process can approach the batch results. That gap is the central engineering question in the latest announcement.
Purification Results Strengthen the Integrated Flowsheet
On the purification side, ECU demonstrated that a single pass through EMC’s in-house DRE medium could reduce the potassium-to-rubidium ratio to approximately 1.5 to 2:1, with consistent results over at least 20 cycles. Bipolar membrane electrodialysis also removed the desorption agent while retaining rubidium in solution, allowing the solution to be recycled through the DRE medium.
ECU estimates, based on measured selectivity coefficients, that the integrated process could produce rubidium purity above 98%. That figure remains a projection rather than a validated outcome: the company says further integrated process testwork is required. The purification work is linked to EMC’s patent-pending technology and is being progressed alongside manufacturing capability for the DRE medium.
Mt Edon Moves From Laboratory Work Into Funding and Engineering
EMC has validated production of its granulated DRE medium at a multi-hundred-gram scale and is commissioning equipment intended to support continuous manufacture at a multi-kilogram-per-day rate. Several hundred kilograms of precursor material have been procured for the next stage.
The announcement arrives after EMC appointed Hall Chadwick as a strategic adviser to explore funding and commercial pathways for Mt Edon, including US and allied market opportunities. The company’s latest work now includes refining the roasting process, completing integrated membrane and DRE trials, finalising washing-stage optimisation and preparing a Class 5 operating expenditure estimate based on bench-scale data.
Resource Scale Still Depends on a Workable Process
Mt Edon hosts an indicated and inferred resource of 4.3 million tonnes grading 0.23% Rb₂O, containing 9,800 tonnes of contained Rb₂O, according to the company. The resource is shallow and reported within a granted mining lease, but the project still requires engineering scoping work, mining proposal approvals, pilot plant funding and additional scale-up evidence.
That makes the next kiln trials more important than another headline recovery number from batch work. Until EMC demonstrates consistent continuous roasting and validates the projected purification performance in an integrated circuit, Mt Edon remains a promising processing project at the boundary between laboratory success and commercial proof.
Bottom Line?
The project has cleared an important laboratory milestone, but continuous kiln performance and pilot plant funding will determine whether that progress can become a credible development pathway.
Questions in the middle?
- Can the rotary-kiln modifications lift continuous recovery from the preliminary 50% to 60% range and reduce variability?
- Will integrated DRE and membrane testing validate the projected rubidium purity above 98%?
- How will EMC fund the pilot plant, engineering studies and approvals while its processing route remains under development?