Could Pit Optimisation Risks Affect Paris Silver Project’s Next Phase?

Technical Advances Boost Project Potential

Investigator Resources has provided a detailed update on its Definitive Feasibility Study (DFS) for the Paris Silver Project in South Australia, highlighting technical improvements that could materially enhance the project's economics and operational efficiency. Central to this update is a roughly 6% uplift in silver recovery achieved by refining the primary grind size from 75 microns to 53 microns in the dominant ore types, a change that promises higher metal extraction rates.

Alongside metallurgical gains, the company has completed a revised pit optimisation study incorporating updated cost inputs and a higher silver price assumption of A$70 per ounce, notably below the current spot price near A$95. This optimisation has led to a substantial reduction in the economic cut-off grade from 43.5 g/t silver in the 2021 Pre-Feasibility Study to a range of 22–27 g/t, depending on host rock type. The lowered cut-off grade translates into an estimated 13 million ounce increase in contained silver within the optimised pit shell, significantly expanding the mineable inventory.

Improved Strip Ratio and Mine Design Flexibility

The updated pit design also delivers a markedly improved strip ratio, dropping from 8.4 – 1 to approximately 4.2 – 1. This reduction means less waste rock will need to be moved per unit of ore mined, enhancing operational efficiency and potentially lowering mining costs. The staged pit shells proposed allow for early extraction of higher-grade material, supporting stronger early cash flows and reducing initial capital requirements. This sequencing strategy is expected to bolster the project's financeability by mitigating early-stage risks.

Importantly, the optimisation results demonstrate robustness across a range of silver price scenarios, indicating that the project design is resource constrained rather than price constrained. This stability is a valuable attribute in the volatile silver market, providing confidence that the mine plan will not require significant redesign under fluctuating prices.

Metallurgical Testwork Validates Processing Approach

Comprehensive metallurgical testing conducted by Bureau Veritas confirms that the Paris mineralisation is amenable to conventional cyanide leaching, with consistently high silver recoveries across key lithological domains. The finer grind size not only improves recovery but also maintains scalability, with bulk composite leach tests achieving nearly 80% silver extraction. The potential increase in dolomite-hosted silver mineralisation, which historically shows excellent recovery rates, could further enhance average recoveries as the pit deepens.

Additional comminution, thickening, filtration, and zinc-precipitation tests support a robust and conventional processing flow sheet, underpinning the updated DFS design basis. These metallurgical advances, combined with pit optimisation, are being integrated into detailed engineering, mine scheduling, and cost estimation work currently underway.

Path Forward to DFS Completion

Investigator Resources is progressing towards finalising the DFS, with detailed mine scheduling and process plant design expected to be completed in early 2026. The updated financial model will incorporate these technical improvements to provide a comprehensive economic assessment. The company remains on track to deliver the DFS in the first half of 2026, setting the stage for potential project financing and development decisions.

Managing Director Lachlan Wallace emphasised the disciplined and transparent approach to advancing the DFS, noting the strong leverage of the Paris Silver Project to silver prices and the quality of the underlying resource. The staged development plan aims to translate technical gains into practical, finance-ready outcomes, reinforcing the project's appeal amid a favourable silver market environment.