en.Wedoany.com Reported - Grande Portage Resources Ltd. has announced key progress in backfill material testing at its New Amalga Gold Project near Juneau, Alaska, USA.
The company received preliminary backfill strength test laboratory results from cemented rock fill (CRF) samples. These samples were cast using core material drilled during previous field seasons, with waste rock lithology selected to match the lithologies that will be encountered during mine development and those present in ore sorting tailings.
The samples were cast into test cylinders using a 4% cement binder content and tested for uniaxial compressive strength (UCS) after curing periods of 10 and 17 days. All samples met or exceeded the preliminary strength criteria selected for the primary mining method planned for New Amalga—upward longhole stoping. Based on these results, the company plans to use waste rock from mine development and ore sorting tailings as feed materials for manufacturing CRF backfill. Future tests with higher cement ratios will be conducted to evaluate backfill for downward mining, a secondary mining method planned for a small portion of the project's production that requires higher-strength backfill.
President and CEO Ian Klassen stated that this is an important risk-reduction milestone. The preliminary test results indicate that development waste rock and ore sorting tailings are suitable feed materials for structural backfill at New Amalga. This further validates the small-footprint strategy, which involves returning all waste rock and tailings underground, eliminating the need for permanent surface disposal facilities, thereby reducing surface disturbance, lowering future reclamation obligations, and simplifying environmental permitting.
Currently, New Amalga core samples representing all major rock types in the deposit are undergoing geochemical testing to determine their potential for long-term reactivity (acid generation or metal leaching). Limited previous testing on a small number of wall rock samples conducted between 2020 and 2021 showed favorable preliminary results, indicating a significant net acid-neutralizing potential ratio.
The New Amalga Gold Project is located approximately 25 kilometers from Juneau, the capital of Alaska, and 6 kilometers from a paved road. The resource remains open for expansion in multiple directions, with indicated resources of 1,438,500 ounces of gold at an average grade of 9.47 grams per tonne gold (4,726,000 tonnes) and inferred resources of 515,700 ounces of gold at an average grade of 8.85 grams per tonne gold (1,813,000 tonnes). Based on a preliminary economic assessment study with an effective date of February 11, 2026, the current development concept envisions a small-footprint underground mining operation, transporting material to a third party for off-site processing, with no on-site gold recovery plant or tailings storage facility.
