The publication of the updated feasibility study on Orla Mining’s Camino Rojo Oxide Gold asset in Zacatecas, Mexico, has come with a 54% increase in contained gold reserves and a 3.5-year extension to the mine life of the in-construction project.

The new reserve estimate at Camino Rojo includes a proven and probable total of 67.4 Mt at 0.73 g/t Au and 14.5 g/t Ag, for total mineral reserves of 1.59 Moz of gold and 31.5 Moz of silver.

The updated study outlined open-pit mining of 67.4 Mt of oxide and transitional ore at a rate of 18,000 t/d. Ore from the pit will be crushed to 80% passing 28 mm, conveyor stacked onto a heap leach pad and leached using a low concentration sodium cyanide solution. Pregnant solution from the heap leach will be processed in a Merrill-Crowe recovery plant where gold and silver will be precipitated and doré will be produced. The site’s proximity to infrastructure, low stripping ratio, compact footprint and flat pad location all contribute to the project’s simplicity and low estimated all-in-sustaining costs of $543/oz of gold, the company said.

An after-tax net present value (5% discount) of $452 million was calculated by the study team led by Kappes Cassiday and Associates and supported by Independent Mining Consultants, Resource Geosciences Inc, John Ward Groundwater Consultant, Barranca Group, Piteau Associates Engineering and HydroGeoLogica Inc.

The main notable physical changes from the 2019 feasibility study are an increase in the size of the open pit, heap leach pad, and mine waste dump because of a layback agreement with the adjacent Fresnillo mine, all of which were anticipated in the initial design. While all material to be mined on the Fresnillo concession has been classified as waste in the latest study, Orla sees opportunities to further expand the reserve and resource base following further work on material in this area.

Jason Simpson, President and Chief Executive Officer of Orla, said: “The updated feasibility study for the Camino Rojo Oxide project demonstrates an increase in recovered gold, mine life, and cash flows.

“An already excellent project has been improved due to the hard work of the entire Orla team and I thank them for their efforts. We are pleased to announce this important enhancement and we will continue to optimise this asset as we move through construction and into production.”

Detailed engineering of the project described in the 2019 feasibility study is over 90% complete and procurement is 85% complete, with the start of earthworks announced on November 26, 2020. Since that time, 230 ha have been cleared for construction activities with over 20,000 cu.m of topsoil being removed and stockpiled. Equipment deliveries to site commenced in December, with a total of $78 million of the total project capital committed through purchase orders and contracts.

Orla says the mining contract is being finalised and expected to be in place early in the March quarter, with first gold production planned for late 2021.