Grande Portage Resources Reports Positive Results from Preliminary Strength Testing of Mine Backfill Materials
Grande Portage’s backfill testwork validates its mining strategy, though capital requirements and going concern risks remain unresolved.
Grande Portage Resources Ltd. (GPG) reported that preliminary backfill strength testing for the New Amalga Gold Project met or exceeded the 0.46 MPa Uniaxial Compressive Strength (UCS) target. This result validates the use of mine development waste rock and ore sorter reject material as feedstocks for Cemented Rockfill (CRF).
The findings support the company's "small-footprint" direct-ship strategy by eliminating the need for surface waste storage and tailings facilities. Grande Portage also reiterated key project economics from the February 2026 Preliminary Economic Assessment (PEA) and the July 2024 mineral resource estimate. Future testwork will evaluate higher cement proportions for underhand stoping, a secondary mining method requiring stronger backfill.
Grande Portage Resources Ltd. (GPG) released news that serves as a technical validation of a previously disclosed mining method component rather than introducing a new catalyst. The update does not alter the Preliminary Economic Assessment (PEA) economics, mine life, production timeline, or capital requirements. While the results reduce technical risk regarding backfill suitability, they represent an expected step in the engineering and permitting process. No new financing, offtake agreements, or regulatory milestones were announced alongside the update. The impact is incremental and aligns with prior expectations set by the April 2026 PEA and subsequent field program updates.
Grande Portage Resources Ltd. (GPG) is a pre-revenue junior explorer focused on the New Amalga Gold Project in Southeast Alaska. The flagship project hosts an Indicated resource of 1.44M oz Au @ 9.47 g/t and an Inferred resource of 0.52M oz Au @ 8.85 g/t.
The company’s development strategy utilizes a small-footprint underground mine with sensor-based ore sorting and third-party offsite processing, known as the Direct-Ship Ore model. This approach eliminates the need for an onsite mill, tailings facility, and permanent waste rock storage, thereby reducing CAPEX and the environmental footprint. A Preliminary Economic Assessment (PEA) dated February 2026 shows a $721M after-tax NPV and 56% IRR at $3,200/oz Au. Grande Portage is targeting a production start in 2031, pending permitting.