Cobra Resources (LSE:COBR), the South Australian rare earths exploration and development company, reported results from desorption tests conducted by the Australian Nuclear Science and Technology Organisation (ANSTO) on samples from its Wudinna Rare Earths Project.
The tests examined recovery rates for neodymium, praseodymium, dysprosium and terbium, the key magnet rare earth elements, across varying concentrations of ammonium sulphate (AMSUL) and pH levels using site-sourced saline groundwater.
At the Boland prospect, cutting AMSUL concentration from the industry-standard 0.5 molar to 0.3 molar reduced magnet rare earth recovery by only 9%, from 77% to 70% for neodymium and praseodymium.
Acidified groundwater with no added AMSUL still recovered around half of the key magnet and heavy rare earths at Boland.
Lower reagent use also cut uranium mobilisation, with uranium recovery falling from 29% to 5% as AMSUL was reduced from 0.5 molar to zero at pH 3.
Cobra said the lower-reagent cases will be weighed against reduced recovery for potential benefits including lower reagent cost, less exposure to AMSUL supply and pricing, and reduced ammonium and sulphate loading on the confined aquifer.
"This operating flexibility matters because recovery cannot be assessed in isolation," said Rupert Verco, Managing Director.
The results will feed into the Wudinna Scoping Study, which will assess recovery, reagent consumption and solution chemistry together to define preferred operating parameters.
Cobra said it expects to announce a maiden Mineral Resource Estimate shortly, ahead of further Scoping Study updates.
News Intelligence what this means for the company
Cobra's desorption tests show rare earth recovery holds up well even when cutting ammonium sulphate (AMSUL) reagent use sharply—neodymium and praseodymium recovery drops only 9 percentage points (77% to 70%) when AMSUL concentration falls from industry-standard 0.5 molar to 0.3 molar. This operating flexibility feeds directly into the upcoming Wudinna Scoping Study and matters because it opens a trade-off: lower reagent costs, reduced AMSUL supply risk, and less aquifer loading against modest recovery loss—a practical pathway to more resilient and lower-cost processing that the company will now model formally.
The test results narrow a key uncertainty in Wudinna's path to production: reagent intensity and cost. Cobra can now enter the Scoping Study with evidence that it does not need to run at industry-standard chemical concentrations to achieve acceptable recovery, potentially improving project economics and reducing operational risk—both material to a development-stage rare earths asset.
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