Recovery improved as the reagent dose fell
Research note — 17 September 2026. Commissioned and paid for by Mount Ridley Mines Limited.
Mount Ridley Mines reported the third and final leach test from its initial Selectro programme on the Grass Patch composite. Test 3 used approximately half the reagent dose applied in Tests 1 and 2 while producing the programme's strongest scandium and rare earth recoveries.
- Scandium: 91.8% recovery, up from 80.0% in Test 2.
- Heavy rare earths: up to 86%, averaging 84%, compared with 78.5% in Test 2.
- Light rare earths: up to 81%, averaging 77%, compared with 72.5% in Test 2.
- Gallium: 41.5% at the lower reagent dose, down from 55.8% but still above zero recovery under the HCl baseline.
The same unbeneficiated eight-sample T3803 composite was used in all three Selectro tests. Test 3 ran at low temperature and atmospheric pressure, with maximum recoveries reached in under four hours of a 24-hour test.
What changes in the investment case
The result indicates that Selectro's recovery profile can be adjusted through the leaching regime and suggests reagent consumption may be lower than previously assumed. Mount Ridley has not yet identified the lower limit of reagent concentration and intends to incorporate Test 3 into updated process economics and scoping assumptions.
At 91.8% recovery, Grass Patch's 47,357 tonnes of contained scandium equates to approximately 43,500 tonnes of potentially recoverable metal, compared with roughly 37,900 tonnes at the 80% recovery assumption used in our initiation. These figures are Cashu Research estimates, not company guidance, and do not represent recovery to a final saleable oxide.
We reiterate our Speculative Buy rating and maintain our A$0.144 price target. The target remains based on the contained scandium resource and carries no value for gallium, rare earths or Selectro licensing.
What remains to be proven
The results are initial laboratory-scale testwork on one unbeneficiated composite. Selectro has not yet been demonstrated on beneficiated feed, a bulk sample, pilot scale or third-party material. Impurity behaviour, downstream separation, capital costs and recovery through to a saleable product also remain unquantified.
Flotation testwork is under way, followed by reduced-reagent testing on beneficiated bulk material. Mount Ridley also plans external validation and testing on third-party feed. We continue to value Selectro at zero until evidence from material outside Grass Patch is published.
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