How Strong Are Australian Gold and Copper’s Achilles Metallurgical Results?

Metallurgical Breakthrough at Achilles

Australian Gold and Copper Ltd (ASX, AGC) has announced encouraging metallurgical test results from its Achilles deposit in the Cobar Basin, New South Wales. The company’s recent flotation and leaching trials on a 52-kilogram composite sample derived from seven diamond drill holes have demonstrated robust recoveries of precious and base metals, a critical milestone as AGC advances toward a maiden Mineral Resource Estimate.

The composite sample, carefully selected to represent a range of mineralised intervals while excluding extreme high grades to avoid bias, yielded combined flotation and leaching recoveries of 83.0% for silver and 90.3% for gold. Lead and zinc recoveries were particularly strong at 92.2% and 95.7%, respectively, with concentrate grades reaching up to 1,267 grams per tonne for silver and 32.8% for zinc.

Sequential Flotation Shows Promise

Beyond bulk flotation, AGC initiated sequential flotation test work aimed at producing separate concentrates for silver-gold-lead and zinc. This approach yielded a high-grade silver-gold-lead concentrate grading 2,276 g/t silver, 9.2 g/t gold, and 41% lead, alongside a zinc concentrate grading 59.6% zinc. While these results are promising, the company acknowledges that further optimisation is required to enhance selectivity and metal recoveries, particularly to refine the separation of metals and to explore copper recovery potential.

Defining Silver Equivalency to Support Resource Reporting

In a significant development, AGC has established a new silver equivalency formula that incorporates silver, gold, zinc, and lead recoveries and prevailing metal prices. This formula will underpin future resource estimations and reporting, providing a comprehensive metric to express the combined value of the deposit’s metals. The silver equivalent calculation factors in recoveries from flotation and leaching, reflecting realistic processing outcomes.

Managing Director Glen Diemar highlighted the importance of this work, stating that the metallurgical results confirm Achilles hosts robust, recoverable metals with strong flotation performance. He also indicated that the silver equivalency framework sets the stage for upcoming exploration results and the maiden resource estimate, expected in the coming months.

Context Within the Cobar Basin

The Achilles deposit’s metallurgical characteristics align well with historical precedents in the Cobar Basin, where bulk flotation has been successfully employed, notably at the Hera Mine. AGC’s test work builds on this regional expertise, reinforcing the deposit’s potential economic viability. The company’s methodical approach, including the use of industry-standard laboratory techniques and a representative composite sample, lends credibility to the findings.

Looking ahead, AGC plans to continue refining the sequential flotation process and to investigate copper recovery, which remains an open question. These efforts will be critical to maximising the value extracted from the deposit and to informing the forthcoming resource estimate.