Impact Minerals (ASX:IPT) advances standalone SOP and hydrochloric acid pathway from WA lake clays

Impact Minerals has outlined a second potential development pathway at its Lake Hope project in Western Australia, centred on producing sulphate of potash and hydrochloric acid from lake clays using a salt calcination process that operates separately from, and alongside, its High Purity Alumina strategy.

The update shifts part of the project narrative from a single product focus to a multi product flowsheet, supported by bench scale metallurgical testwork and an active Scoping Study program.

Highlights

• Standalone pathway identified to produce sulphate of potash and hydrochloric acid from lake clays, separate from the Lake Hope High Purity Alumina process
• Metallurgical testwork delivered sulphate recoveries above 94% and chlorine extraction above 98% from salt calcination tests
• Process does not rely on evaporation ponds and is designed to avoid climate and harvesting risks seen in earlier Australian SOP projects
• Several lakes near Salmon Gums have been identified and staked as potential early feedstock sources under an 80:20 joint venture with Playa One
• Scoping Study in progress covering potash resource definition from previous drilling and technical and commercial viability
• Further metallurgical optimisation and market engagement programs are scheduled, with next phase test results expected in Q2 2026

The company reports that salt calcination of lake clays, where clay is mixed with commercially available chloride salts and heated, produces a solution containing potassium and sulphate for SOP recovery, chlorine gas that can be captured to make hydrochloric acid, and an aluminium rich solid residue.

Bench scale work completed at ALS Metallurgy in Balcatta tested salt additions between 15.5% and 45% and temperatures between 450°C and 750°C, with extractions ranging up to 94.75% K₂O, 94.74% SO₃ and above 98% Cl, depending on conditions. The highest extractions were recorded at higher temperatures and lower salt dosages.

The company states that SOP is not currently produced in Australia and that all domestic requirements are imported, while hydrochloric acid is widely used across the Eastern Goldfields in gold processing, chemical manufacturing and clay hosted rare earth projects.

Market enquiries cited in the release indicate SOP prices in Western Australia generally range from A$800 to A$1,200 per tonne and delivered hydrochloric acid prices generally range from A$650 to above A$1,000 per tonne, depending on location.

The Salmon Gums project area, held within the Playa One joint venture in which Impact has an 80% beneficial interest, has been assembled around lakes considered suitable for the potash and acid flowsheet and closer to potential Wheatbelt and Goldfields markets.

The release notes that these lakes could serve as early feedstock sources alongside Lake Hope for a mining and processing operation located nearer to those end users.

Impact Minerals Managing Director Dr Mike Jones said the alternative route opens an additional product stream from the same lake systems, stating

“While our main focus remains on HPA development, we now see a potential route to produce sulphate of potash and hydrochloric acid as primary products through a relatively straightforward processing method.”

He also confirmed that further testing, Scoping Study work and partnership discussions with fertiliser, chemical and industrial groups are planned.

From a project sequencing perspective, the company describes the potash and acid opportunity as capable of being developed either as a standalone operation or alongside the Lake Hope HPA project, with potential shared infrastructure and regional synergies, subject to Scoping Study outcomes.

The next stage centres on metallurgical optimisation, crystallisation refinement, chlorine capture testing and development scale assessment, which will determine how this additional flowsheet fits within the broader Lake Hope and Salmon Gums development framework.

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