US-based miner i-80 Gold has announced the preliminary economic assessment (PEA) for its Granite Creek Underground Project in Nevada, projecting life of mine (LOM) sustaining capital costs at $105m.
The project’s site is located where the Battle Mountain-Eureka and Getchell gold trends intersect. It is the first in i-80 Gold’s portfolio slated for redevelopment and is progressing towards full operational capacity.
According to i-80 Gold, the Granite Creek Underground site, which has a history as a mining location, benefits from existing infrastructure.
Of the total LOM sustaining capital, 65% is allocated for ongoing capital development. The PEA does not factor in drilling operations conducted during 2023 and 2024 or the underground water management strategies planned for 2025.
Consequently, i-80 Gold’s production expectations for 2025 are under development and differ from the PEA’s projections. The company forecasts gold production of between 20,000 to 30,000 ounces this year at the Granite Creek Underground site.
The PEA outlines several key aspects, including an eight-year projected life for this high-grade underground gold mine with annual production averaging around 60,000 ounces post-ramp-up.
Estimated LOM cash costs are $1,366 per ounce, while all-in-sustaining costs are calculated at $1,597 per ounce. The updated mineral resource estimate reveals a measured and indicated gold resource of 261,000 ounces at 10.5 grams per tonne (g/t) and an inferred resource totaling 326,000 ounces at 13.0 g/t.
These estimates exclude recent drilling data but foresee further exploration in the South Pacific zone by 2025 to be part of a feasibility study planned for Q4 2025.
The economic projections of the project are based on a gold price of $2,175 per ounce, forecasting undiscounted after-tax cash flows of $197m and an after-tax net present value (NPV) of $155m using a 5% discount rate.
Should the gold price rise to $2,900 per ounce, these numbers increase to $420m in cash flows with an NPV of $344m, said i-80 Gold.
The primary mining method employed is underhand drift and fill.
Until i-80 Gold’s Lone Tree facility becomes operational in 2028, refractory material will be processed externally, potentially leading to lower payability on gold produced by approximately 30%.
The average processed gold grade is projected to be 11.6g/t with a recovery rate of 78%, which could increase to about 92% following refurbishment of the company’s autoclave facility.
i-80 Gold CEO Richard Young said: “Our exploration results at Granite Creek Underground to-date suggest significant potential for resource growth and expansion.
“As a result, an extensive drill programme is planned in the coming years to realise that potential. The PEA also demonstrates that once our Lone Tree autoclave is refurbished as anticipated in 2028, production and cash flow are expected to increase materially.”
Granite Creek Underground has received full permits and is operational. The property includes both the underground mine and an adjacent open pit deposit currently in the permitting phase.
Situated roughly 43km northwest of Winnemucca in Humboldt County, Nevada, it is positioned near significant operations such as Nevada Gold Mines’ Turquoise Ridge Complex.
Since beginning operations in 1980, the property has yielded nearly one million ounces of gold. Current efforts focus on infill drilling programmes across multiple zones aimed at resource expansion.
An open pit resource estimate alongside a PEA is planned for Q4 2025. This will be complemented by a feasibility study providing updated operational plans for Granite Creek Underground, said i-80 Gold.
