97% Radium Removal Points Cobra Toward a Higher-Value Wudinna Product

• Radium removal, measured as radium-225, exceeded 97% in initial purification test work at the Australian Nuclear Scientific Technology Organisation (ANSTO).
• Actinium removal reached up to 90%, and the concentration of lower-value lanthanum fell by 1% to 30%.
• More than 90% of the higher-value magnet and heavy rare earth elements were retained.
• Final recoveries and the distribution of each element remain subject to confirmation through solid assays and a complete solid-liquid mass balance.
• The step could raise the relative weighting of magnet and heavy rare earths in Cobra's mixed rare earth carbonate product.
• Results feed engineering design and the scoping study, with 4 further work streams running at ANSTO.

Company Overview

Cobra Resources (LSE: COBR) is a South Australian critical minerals developer advancing assets across all stages of the pre-production pathway. In 2023, the company identified the Boland ionic rare earth discovery at its Wudinna Project in the Gawler Craton, described as Australia's only rare earth project suitable for in situ recovery (ISR) mining, a low-cost, low-disturbance method that removes the need for excavation. In 2025, it optioned the Manna Hill Copper Project in the Nackara Arc and sold its Wudinna Gold Assets to Barton Gold for up to A$15 million in cash and shares. Its portfolio also includes the Deloraine rare earth project in northern Tasmania.

What the ANSTO Test Work Removed

The Australian Nuclear Scientific Technology Organisation (ANSTO) applied its proprietary radionuclide removal technology to Cobra's Wudinna flowsheet as part of its ongoing support to the company's process development. The testing was aimed at supporting a forthcoming scoping study.

Radium removal, measured as radium-225, was greater than 97%. Actinium removal reached up to 90%, and the concentration of lanthanum, the lowest-value element in the mix, fell by 1% to 30%. More than 90% of the higher-value magnet and heavy rare earth elements were retained through the same step.

Final recoveries and the distribution of each element remain subject to confirmation through solid assays and a complete solid-liquid mass balance. The figures reported are indicative results from preliminary test work.

A Higher Weighting of Magnet & Heavy Rare Earths

The initial results indicate that the purification step has the potential both to reduce radionuclide concentrations and to selectively remove a proportion of lower-value lanthanum before final product precipitation. That combination could raise the relative weighting of magnet and heavy rare earths in Cobra's mixed rare earth carbonate (MREC) product, and reduce the volume of lower-value material presented to downstream separation.

The results build on earlier test work that removed cerium from the metal-bearing solution recovered by ISR. Taken together, the two steps give a potential pathway to a cleaner, higher-value intermediate product, and the technical and economic benefits of integrating the process with mid-stream separation will be evaluated within engineering and scoping studies.

Managing Director of Cobra Resources, Rupert Verco, sets the removal figures against what the company is trying to protect in the product:

"The work demonstrates substantial removal of radium and actinium, while also selectively reducing lower-value lanthanum and retaining magnet and heavy rare earths that underpin product value."

The purification step is one stage in a flowsheet the company is still assembling.

Where the Purification Step Fits

Cobra discovered the Wudinna rare earths in 2023. Mineralization is ionically bound to clays and organics within the sands of the Narlaby Palaeochannel, and it occupies a permeable sand horizon inside an aquifer saltier than sea water, confined above and below by impermeable clays.

ISR recovers metal by injecting a mildly acidic ammonium or magnesium sulfate solution through engineered arrays of drill holes, using the confining clays to direct the flow and lower the acidity applied to the ore body. The loaded solution is then pumped back to surface through extraction holes, with no excavation and no ground disturbance. Capital costs are low because no material is moved and no conventional plant is needed to process ore.

Bench scale testing has confirmed that the Wudinna mineralization is amenable to ISR. Confined aquifer ISR accounts for more than 60% of world uranium production, and Cobra is aiming to be the first to apply it to rare earths.

Next Steps

Further testing is underway at ANSTO to support engineering assessment and the scoping study. Test work dissolving Cobra's MREC and applying ANSTO's purification technology is complete, with results pending, as is optimization of the lixiviant, the leaching solution injected underground, using groundwater at a lower concentration of ammonium sulfate.

Resource recovery evaluation is in progress, with more than 40 diagnostic leach tests performed on samples from across the mineralized footprints. Bench scale ISR trials on ore composites from the Boland and Head prospects have reached the sighter column stage, with columns being prepared. Those trials will use the lixiviant conditions defined by the earlier tests and will inform the conditions used in the planned small scale production study.

Verco puts the test work in sequence:

"This is the first stage of evaluating this purification step. We will now incorporate these results into engineering design and the scoping study, including optimization of operating conditions and the overall economic contribution of the process."

Engineering design, further test work and scoping study assessment will determine the operating configuration, recovery assumptions and potential development economics at Boland.

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