Mount Ridley’s Selectro test adds evidence for third-party processing

Mount Ridley Mines’ latest Selectro result strengthens the case for testing the process on material beyond the company’s own Grass Patch deposit. In its 21 October 2026 announcement, the company reported 94.9% gallium extraction from a bauxite composite supplied by Australian Silica Quartz Group (ASX: ASQ). The result adds to earlier aluminium and iron recoveries from the same test, but it does not yet establish a repeatable commercial process or change the valuation treatment in the related Cashu Research report.

Mount Ridley Mines (ASX: MRD) described the test as its first third-party bauxite test. The composite was supplied by ASQ, and the company says its wholly owned, patent-pending Selectro process extracted 94.9% of the gallium into solution. The same single leach also produced 91.9% aluminium extraction and 96.7% iron extraction, with the leach operated below 100°C.

The distinction between one test and multiple tests matters. The gallium result is an additional assay from the same leach that generated the aluminium and iron results; it is not a second successful test. Taken together, the results provide evidence that Selectro can dissolve three targeted metals from a third-party bauxite feed in one test. They do not yet demonstrate repeatability across different deposits or prove that the process can support a licensing business.

That is progress against the first milestone identified in Cashu Research’s 8 October 2026 update, which framed Selectro as a potential Western processing route rather than only a method for treating MRD’s own material. The new result therefore broadens the evidence base for a third-party processing opportunity, while leaving the more difficult development work outstanding.

The bauxite composite was prepared from 16 vacuum drill samples taken across four holes at ASQ’s Athena and Ceres prospects in Western Australia’s Darling Range. Its reported head grades were 80 parts per million gallium, 41.9% aluminium expressed as Al₂O₃ and 13.6% iron expressed as Fe₂O₃.

The reported recoveries are extraction-to-solution results. Gallium required the more sensitive ICP-MS assay method because its concentration in the feed was low, and MRD says the recoveries were calculated from solution assays and calculated head grade. A 94.9% leach recovery therefore does not mean that 94.9% of the gallium has become saleable metal. Separation, purification and any later processing can create additional losses and costs.

The result also should not be treated as proof that a previously identified Grass Patch trade-off has been resolved. On Grass Patch material, gallium recovery fell to 41.5% at the lower reagent dose used in Test 3, compared with 55.8% in Test 2. Those figures relate to different material and test conditions from the bauxite result, so they are not directly comparable.

Bauxite is the principal feedstock for aluminium and also the main source of primary gallium. Gallium is used in gallium arsenide and gallium nitride semiconductors for applications including communications, defence systems and power electronics. MRD’s announcement, citing the US Geological Survey, says China accounts for approximately 99% of global primary low-purity gallium production.

That concentration helps explain interest in alternative sources, but it does not establish a market or customer for Selectro. The company compares its result with approximately 70% gallium extraction into liquor in the conventional Bayer process and notes that recovering gallium from Bayer liquor requires a dedicated circuit. The comparison is encouraging, but it is not a like-for-like commercial plant trial and cannot establish lower total costs or commercial superiority across different bauxite feeds.

MRD says the Selectro leach left a silica-rich residue, with more than 90% of the silica remaining in that residue rather than generating conventional Bayer red mud. That could become an important part of the process story, but a different residue is not automatically a saleable by-product or proof of a lower overall environmental footprint.

Residue handling, reagent recycling, water use and performance at larger scale still need to be assessed. These considerations are part of the gap between a positive laboratory extraction result and a process that can operate commercially.

With gallium, aluminium and iron all extracted above 90% in this test, MRD says its immediate focus is separation and purification pathways for both bauxite and Grass Patch feeds. The company’s announced next steps are to separate and purify gallium from the Selectro leach solution, report results from a second bauxite test, test additional third-party feedstocks, and progress the design and construction of a Selectro demonstration plant.

Those are planned activities, not completed milestones. Product purity, repeatability, reagent consumption, operating costs, funding and scale-up will matter as much as the headline extraction percentages. In particular, evidence of usable products and complete mass balances would help show how much of the metals dissolved in the leach can ultimately be recovered and sold.

Relative to the 8 October 2026 research, the gallium assay is progress on the third-party feed milestone, not a completed commercialisation case. It strengthens the multi-metal processing opportunity alongside the earlier aluminium and iron results, while the resource-based valuation remains unchanged in this article.

The focus now moves to usable products, repeatable performance at larger scale and credible economics. Evidence on those points would be more meaningful for assessing potential licensing value than another headline leach percentage alone. The original research and the company’s 21 October 2026 announcement provide the relevant context, while the laboratory result and planned development activities do not establish commercial viability.