Mount Ridley’s giant scandium resource gets a processing boost

Scandium resource reaches 946.1 million tonnes

Mount Ridley Mines Limited (ASX:MRD) has put an unusually large number at the centre of its September quarter report: a 946.1 million tonne Inferred scandium resource at the Grass Patch Critical Minerals Project, grading 50.1 parts per million scandium and containing 47,357 tonnes of scandium metal. On the company’s stated comparison, it is now the world’s largest publicly reported JORC-compliant scandium resource.

The estimate covers Blocks 1 and 2 and was built from re-assays of 3,271 historical aircore and diamond drill pulp samples. It remains entirely Inferred, and the Phase 2 re-assay results described in the report have not been incorporated into the 946.1Mt estimate. That distinction matters: the headline tonnage has grown, but the next test is whether further drilling and modelling can improve confidence as well as scale.

Re-assays extend mineralisation beyond the current estimate

Phase 2 work identified shallow, high-grade scandium mineralisation as far as 8km beyond the existing Block 1 and Block 2 resource boundaries. At Block 1, the extensions run roughly 4km to 5km south and south-east; at Block 2, the company reported extensions of about 7km to 8km north and 4km to 5km west and north-west. Mineralised intersections between the blocks also point to possible continuity across the intervening corridor.

Reported results included 22 metres at 119.41ppm Sc₂O₃ from 12 metres in MRAC1036 and 40 metres at 102.09ppm Sc₂O₃ from 18 metres in MRAC1040, with both holes ending in mineralisation. The scale of the exploration footprint was outlined in Phase 2 scandium extensions, but the company still needs further re-assaying, infill drilling and step-out drilling before those results can support a revised resource.

Selectro improves scandium recovery while gallium retreats

The processing story also advanced, though not in a straight line. Selectro Test 3 recovered 91.8% of scandium from the same unbeneficiated Grass Patch composite used in earlier work, up from 80.0% in Test 2. Average heavy rare earth recovery rose to 84%, while average light rare earth recovery reached 77%, with the test using approximately half the Test 2 reagent dose. The result builds on the 91.8% scandium recovery test reported in September.

Gallium moved the other way, falling to 41.5% from 55.8% in Test 2. That trade-off is significant because Mount Ridley’s strategy is built around recovering scandium, gallium and rare earth elements through a shared leach circuit. The tests were laboratory-scale and based on a composite sample, so the improved scandium and rare earth figures are encouraging process indicators rather than evidence of a demonstrated commercial flowsheet.

Flotation and patent work move Selectro towards scale-up

Mineralogical work using TIMA found the tested rare earths predominantly hosted in phosphate minerals including xenotime, crandallite-group phosphates and monazite or rhabdophane. Mount Ridley is now testing whether flotation can produce a rare earth-bearing concentrate before Selectro leaching, potentially reducing the volume of material requiring downstream treatment. One of three planned flotation tests had been completed by quarter end, with further work being interpreted and refined by flotation specialist Dr Kwan Wong.

The company is also advancing a scoping study for a planned demonstration plant and has lodged a provisional patent application covering adaptations of Selectro chemistry for industrial feedstocks. Initial bauxite testing reported after quarter end recovered 91.9% aluminium, 96.7% iron and, in further assays, 95% gallium from a selected composite. Those results are potentially useful for the technology’s commercialisation case, but the company cautioned that the composite is not representative of the broader bauxite deposit and further separation, purification and optimisation work remains.

Placement funds technical program, with scale-up still unfunded beyond current cash

Mount Ridley raised approximately A$2 million before costs through a placement of 60.6 million shares at A$0.033 each. The funds are earmarked for flotation, bulk metallurgical testwork, scoping studies, resource definition, Selectro optimisation and exploration. The company reported A$3.065 million in cash at 30 September and quarterly net operating cash use of A$792,000, equivalent to 3.87 quarters of funding on the Appendix 5B calculation.

That balance provides room for the next work packages, but not a completed development pathway. The immediate milestones are Phase 3 re-assay results from another 2,800 historical pulps, flotation outcomes, bulk and pilot-scale Selectro testing, and decisions around the demonstration plant. Until those stages are completed, the investment case rests on whether laboratory recoveries, a very large but Inferred resource, and a multi-metal processing concept can be converted into a repeatable and financeable operation.