Ardea Resources Confirms Design Changes for Goongarrie Hub Feasibility Study

• Definitive Feasibility Study remains on schedule for completion in first half 2026, with material design advances since July 2023 Pre-Feasibility Study
• Processing capacity consolidated to 3.5 million tonnes per annum high pressure acid leach only, removing the 0.5 million tonnes per annum atmospheric leach circuit
• Sale product changed from mixed hydroxide precipitate to mixed sulphide precipitate to improve payability and market optionality
• First decade mine plan centred on higher grade, near plant goethite deposits at Goongarrie South, Big Four and Scotia Dam
• Major Project Status renewed by Australian Federal Government in October 2025

Ardea Resources (ASX:ARL) is a mineral exploration company operating in Western Australia. The company is developing the Kalgoorlie Nickel Project through a joint venture with GH Nickel Pty Ltd, representing Sumitomo Metal Mining and Mitsubishi Corporation. The company holds 854 million tonnes at 0.71% nickel and 0.045% cobalt, containing 6.1 million tonnes of nickel and 386,000 tonnes of cobalt. The Goongarrie Hub accounts for 584 million tonnes of this resource, with Ardea holding an 82.5% interest in the joint venture targeting over 30,000 tonnes per annum of nickel production.

Definitive Feasibility Study Progress and Design Changes

The Definitive Feasibility Study has confirmed removal of the 0.5 million tonnes per annum atmospheric leach circuit, consolidating ore processing through an expanded 3.5 million tonnes per annum high pressure acid leach circuit. This represents a change from the July 2023 Pre-Feasibility Study, which was based on combined 3.0 million tonnes per annum high pressure acid leach and 0.5 million tonnes per annum atmospheric leach capacity producing mixed hydroxide precipitate.

The simplified flowsheet reduces ore feed types and unit operations, decreasing process plant design complexity. Acid demand is materially reduced, resulting in a smaller process plant footprint and lower carbon dioxide emissions. The change reduces reliance on deeper saprock mining for neutralising material, allowing pit optimisation based on nickel and cobalt grade and acid consumption.

The high pressure acid leach autoclave configuration targets 3.5 million tonnes per annum throughput, consistent with the largest autoclave that can be transported to the Goongarrie site. The study is evaluating modest increases in operating temperature to improve nickel extraction whilst remaining within proven operating envelopes, subject to final ore characterisation data, testwork and engineering.

Flowsheet Optimisation and Product Configuration

The study has confirmed a change in sale product from mixed hydroxide precipitate to mixed sulphide precipitate. According to the company, this change is expected to deliver improved payability relative to mixed hydroxide precipitate. Mixed sulphide precipitate is suitable feed for a range of global nickel sulphide smelters and refineries, providing broader market flexibility for Ardea's 25% offtake entitlement.

The product change requires additional utility infrastructure, including hydrogen, hydrogen sulphide and nitrogen generation plants. The incremental capital requirement is being incorporated into Definitive Feasibility Study estimates and evaluated alongside the revenue and marketing outcomes.

Managing Director Andrew Penkethman stated:

"Several key design improvements have now been fully validated, most notably the simplified HPAL only flowsheet and the move to MSP as our sale product. These decisions strengthen the technical and commercial profile of the project."

Workstream Evaluations and Future Development Options

Several workstreams remain subject to Definitive Feasibility Study outcomes, final metallurgical testwork results, resource reinterpretation, optimisation, mine planning and Ore Reserve completion in first half 2026. The study is assessing potential simplification of the comminution circuit by increasing reliance on semi autogenous grinding using shallow, hard low grade ore as grinding media. According to the company, objectives include reducing capital and operating costs associated with ball mills and steel grinding balls, and improving utilisation of near surface material not optimal for high pressure acid leach feed.

Post feasibility work may evaluate pumped slurry transport of beneficiated ore from Goongarrie Hill and Highway satellite pit areas to the Goongarrie process plant as an alternative to road haulage. The company states potential benefits include reduced operating cost and road haulage exposure on the Goldfields Highway, ability to backfill exhausted pits with waste material, and more efficient long term use of mine voids.

The study will quantify scandium within the Mineral Resource Estimate block models. The potential for future scandium product streams is being considered at a conceptual level, including allowance in the site plant layout for a scandium refinery. Any such developments would be subject to further study, market analysis, capital assessment and regulatory approvals. The project includes several gold prospects, including the Big Four deposit with an Inferred Mineral Resource of approximately 178,000 tonnes at 2.7 grams per tonne for 15,000 ounces of gold. Post feasibility work will evaluate potential for early custom milling of gold to generate additional revenue.

Next Steps and Project Milestones

The Definitive Feasibility Study remains on schedule for completion in first half 2026. Key remaining inputs include final resource models, updated long term acid and neutraliser requirements under the simplified high pressure acid leach only flowsheet, and optimised pit designs and schedules reflecting confirmed process design changes. A streamlined mine plan for the first decade of operations is being developed, focused on Goongarrie South, Big Four and Scotia Dam.

The company acknowledges sector wide cost escalation since the 2023 Pre-Feasibility Study but has not provided updated project capital or operating cost estimates. Updated cost and financial metrics will be disclosed upon completion of the Definitive Feasibility Study.

Mr Penkethman added:

"We have also made strong progress on refining the approach to mine planning, autoclave optimisation and continue to consider long term value opportunities across additional Critical Mineral by-product production, comminution, and ore transport."

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