Azure Minerals has initiated small-scale mining at its Oposura zinc-lead-silver project in Sonora, Mexico. The current activity is exploiting easily-accessible, high-grade mineralization at a production rate of between 1,500 metric tons (mt) and 3,000 mt/month at grades of 10% to 15% combined zinc and lead. Processing was scheduled to begin in September under a toll-treatment agreement with a third-party sulphide flotation plant.
Azure anticipates that positive cash flow from this small-scale mining activity will support an ongoing feasibility study for full-scale mining and on-site processing. A scoping study published in October 2018 highlighted Oposura as an economically and technically robust, high-margin project, underpinned by low operating and capital costs, high-value concentrate, strong operating cash flows, and a 16-month payback period.
The 2018 scoping study considered a 1,500-mt/d mining operation with an initial six-year mine life. Mining would be from an open pit for three years, followed by underground mining utilizing room-and-pillar extraction for another three years. Production is estimated at 19,000 mt/y of zinc, 10,000 mt/y of lead, and 145,000 ounces per year (oz/y) of silver in separate zinc and lead-silver concentrates.
Major advantages of the Oposura project are uncomplicated geology and straight-forward mining and processing. High-grade massive sulphide mineralization begins at or very near surface at ore grades of 20% plus zinc plus lead.
The current small-scale mining operation is focused on easily accessible massive sulphide mineralization from the Oposura project’s East Zone mineral resource. An open-pit mining contractor mobilized to site in July. Work completed to date has included refurbishing of the 6-kilometer (km) access road between the main highway and the mine site, pre-stripping of overburden from above the massive sulphide horizon, grade-control drilling, and mining and stockpiling of ore.
An underground mining contractor mobilized to site in August. A portal is being established in the western wall of the open pit to access an historic tunnel drive that will be side-stripped to provide 3-m by 3-m mechanized access to the project’s western high-grade zone.
Commenting on the start of small-scale mining, Azure Managing Director Tony Rovira said, “We acquired Oposura in August 2017, and to be commencing an early-stage, low-cost, high-grade mining operation within 24 months is a great achievement. This operation allows Azure to realize early cash-flow that will help fund the ongoing feasibility study, which will ultimately lead to full-scale production at Oposura.”
Azure Minerals is an Australian company headquartered in West Perth, Western Australia.