Vancouver-based Integra Resources is contemplating a larger scale openpit mining project at DeLamar, in south-western Idaho, CEO George Salamis reported on Wednesday, announcing the outcomes of a prefeasibility study (PFS).

Following on from the 2019 preliminary economic assessment, the newly-released PFS is a materially different and larger-scale project. The two-stage project now entails a larger openpit mining scenario that combines heap leaching and milling to achieve average production of 163 000 gold-equivalent ounces a year for the first eight years, a mine life of 16 years and a life-of-mine (LoM) all-in sustaining cost (AISC) of $955/oz.

The staged development also means that production starts with an openpit heap-leach operation, allowing for lower capital and operating cost requirements. The heap-leach phase will produce 136 000 gold-equivalent ounces at an AISC of $813/oz.

“We believe that in an inflationary environment, such as the one that our shareholders and stakeholders are currently experiencing, having a multi-phase development stage is critically important, and demonstrates maximum flexibility and transparency,” said Salamis.

The DeLamar PFS calculated an aftertax internal rate of return of 27% and a net present value of $412-million.

Preproduction capital expenditure (capex) is estimated at $282-million and LoM capex at $576-million. The project has a payback period of 3.3 years.

This study also outlines the potential for significant upside opportunities at the DeLamar project, including increased gold and silver recoveries in the non-oxide ore through the use of Albion processing methods, a process that has much lower capital costs than traditional oxidation plants and has yielded promising results in recent test work.

Salamis stressed that the study did not incorporate any of the high-grade gold/silver potential below the Florida Mountain resource envelope.