Mount Ridley's 92% aluminium result meets a key Selectro catalyst

Mount Ridley Mines (ASX: MRD; OTC: MRDMF) has reported Selectro’s first test on material from outside Grass Patch. The first-pass test on third-party bauxite returned 91.9% aluminium extraction and 96.7% iron extraction into solution. The announcement, dated 15 October 2026, says the result extends evidence for the patent-pending process beyond its own critical-mineral feed. It reaches the first off-project test milestone, but it does not establish a commercial flowsheet, a saleable product or licensing revenue.

The key change is feedstock, not simply the recovery percentages. Cashu Research’s 8 October update identified third-party feed, scale, saleable product, economics and intellectual property, and commercial adoption as separate tests of Selectro’s processing opportunity. Earlier work reported on 17 September had shown improved Grass Patch recoveries, but remained within a single feedstock and offered no third-party feed evidence.

This announcement supplies the first off-project result and gives Mount Ridley a basis for further external-feed testing and discussions with potential industry partners. Mount Ridley says the result arrived ahead of the Q1 2027 timeframe previously indicated for third-party testwork. That brings forward evidence on the catalyst, but does not mean the wider commercialisation programme is complete.

Australian Laboratory Services conducted the test on a composite supplied by Australian Silica Quartz Group (ASX: ASQ) from its Darling Range bauxite project in Western Australia. The approximately 1kg composite combined 16 selected vacuum-drill samples from four holes across the Athena and Ceres prospects, drilled in 2013 and 2014.

On an oxide basis, the composite had an aluminium head grade of 41.9% and 91.9% aluminium extraction into solution. Its iron head grade was 13.6%, with 96.7% iron extraction into solution. These are leach-extraction results, not recovery through to finished aluminium, refinery-grade alumina or a qualified iron product. Mount Ridley also says the chemistry has not yet been optimised for bauxite.

More than 90% of the silica remained in the residue, which represented approximately 25% of the original dry feed mass. Mount Ridley describes that residue as pH-neutral and silica-rich, rather than the caustic, iron-rich red mud associated with conventional Bayer refining.

The sample has important limitations. Mount Ridley has not independently verified ASQ’s drilling, sampling or survey data, and the selected composite is not intended to represent the deposit as a whole. External laboratory work on a third-party sample should not be confused with independent validation of an entire commercial process.

Mount Ridley sees potential for Selectro as a lower-temperature alternative to Bayer digestion. The bauxite test ran at below 100°C, compared with the announcement’s approximately 145°C to more than 250°C range for conventional Bayer digestion, depending on the ore. Keeping silica in a different residue and extracting iron alongside aluminium could create different processing and by-product options.

Those are potential advantages, not demonstrated whole-of-process savings. Digestion temperature alone does not establish total energy use, emissions, reagent consumption, capital cost or the cost of producing a saleable product. A pH-neutral laboratory residue also does not prove that environmental, disposal and water-management requirements have been met at scale.

The company identifies licensing to existing refiners as a possible adoption route and sees potential in high-reactive-silica bauxite and smaller deposits. However, no licence agreement or commercial bauxite processing operation is announced in the release.

The next reported item is expected to be a more sensitive gallium assay method, with Mount Ridley expecting results within a week of the 15 October announcement. No bauxite gallium recovery result is reported here, and earlier Grass Patch results cannot be substituted for it.

Further work must also demonstrate separation and purification of aluminium and iron products from the leach solution, including purity, impurities and overall product recovery. Extraction into solution is only part of that pathway. Mount Ridley says Grass Patch flotation testwork is complete and assays are pending; those concentrates are then intended for Selectro treatment, testing a different part of the flowsheet from the bauxite experiment.

Repeatability will require optimisation of the bauxite chemistry and testing of additional suitable feedstocks rather than reliance on one selected composite. The remaining work includes gallium assays, product separation, repeatability, external feeds, and demonstration-plant economics. Mount Ridley says it remains funded to progress the demonstration plant, but that is not confirmation that it has been built or that all future development funding is secured.

The announcement matters because it delivers evidence on a condition explicitly identified in recent Cashu Research. Selectro is no longer supported solely by results on the Grass Patch composite, which is a meaningful advance in the processing thesis.

The distinction is between demonstrating extraction in a selected laboratory sample and proving a commercial business. The next evidence needs to connect extraction to repeatable, saleable products and credible scale-up economics. Selectro remains at laboratory-test stage, and development, funding and commercialisation risks remain substantial.

Cashu’s related MRD research was commissioned and paid for by Mount Ridley Mines Limited. Cashu Research or Cashu Group has received fees for research or corporate communication services from companies mentioned, and its directors, employees or associates may hold or trade those securities. Company test results and plans in this article are attributed to the 15 October announcement. This is general information, not personal investment advice.