For the second time in three months, Evolution Mining (ASX:EVN) has expanded the mineral resource size at its Ernest Henry copper and gold mine in northern Queensland, now exceeding 100 million tonnes of ore containing valuable copper and gold.
Released on Thursday, alongside the company's 2022-23 financial results and annual report, the upgrade garnered overshadowed attention despite its significance for the aging mine. Acquired from Glencore for a total of $1 billion between 2021 and 2022, the Ernest Henry mine's importance was somewhat obscured by the comprehensive report.
Currently, the measured reserve ore stands at 35 million tonnes, complemented by a similar amount of indicated ore reserves and an estimated 31.5 million in the inferred classification.
In a previous update on June 5, which revealed a doubling of ore reserves along with increases in contained copper and gold, Evolution disclosed that a pre-feasibility study extended the mine's life by 17 years to 2040.
Lawrie Conway, CEO of Evolution, stated, "In under 18 months of owning 100% of Ernest Henry, we have doubled copper and gold reserves and extended the mine life out to 2040. By any measure this is an outstanding achievement. The Pre-Feasibility Study demonstrates excellent financial returns, but the most exciting aspect is that all of the outstanding exploration success we are enjoying is not yet captured and will be included in the Feasibility Study that we are now commencing."
Thursday's announcement from the company delved deeper, revealing another increase in reserves at the mine. The updated Mineral Resource estimate for June 30, 2023, indicates a figure of 101.5 million tonnes at 1.25% copper and 0.73g/t gold, amounting to 1.3 million tonnes of contained copper and 2.4 million ounces of contained gold, accounting for mining depletion.
This showcased a 6.7 million-tonne (7%) expansion in the resource size, correlating with a 3% rise in contained gold totaling 76,000 ounces, and an additional 5% or 63,000 tonnes of contained copper, net of mining depletion, compared to the Mineral Resource estimate of December 31, 2022.
Evolution highlighted that the augmentation of the resource size was primarily driven by expansions connecting Ernie Junior to the lower lenses of the Main ore body and the Main ore body's growth below 775 meters—a depth not explored in the initial resource study.
The company underscored that "significant growth opportunities exist beyond currently interpreted mineralization domains," particularly in "depth extensions below the Main ore body and between the Main ore body and Ernie Junior." Additionally, Evolution highlighted prospects at Bert, another distinct area of interest, where mineralization remains open, suggesting the potential for a new ore body parallel and stratigraphically beneath.
The updated Mineral Resource estimate is factoring in drilling outcomes up to June 30, 2023, and is integrated into the Mine Extension Feasibility Study's engineering work. This follows the results of the Mine Extension Pre-feasibility Study, which emphasized a compelling opportunity to prolong the Ernest Henry sub-level cave operation, extending its operational life by 17 years to 2040.
