Report from the Golden Highway: McEwen’s Stock West
2023 Projects in the Pipeline
McIntyre Ballroom

  • Company Name: McEwen Mining Inc.

The Fox Complex Preliminary Economic Assessment (PEA) was announced on January 26, 2022 and is an expansion project based on the sequential underground development and mining of the Froome, Stock West, Grey Fox, and Fuller mineral resources. The PEA includes upgrading the Fox mill, located at the Stock property, to increase throughput capacity to 2,400 tonnes per day and to allow the simultaneous processing of material from multiple deposits.
Located within the Abitibi greenstone belt, the Fox Complex has various gold mineralization occuring within the ankerite alteration zone: (1) free gold associated with shallow dipping quartz veins and stockworks in green carbonate and ankerite-altered ultramafic rocks; (2) gold-bearing pyrite; (3) gold associated with fine-grained pyrite and (4) free gold in steeply dipping sigmoidal quartz veins. 
Although there is a history of exploration and production, Fox remains relatively under-explored. Its land packages have all the criteria characteristic of great exploration projects, including prime location within a prolific mining region, high gold endowment, presence of high-grade mineralization, multiple prospective structural trends, as well as various styles of mineralization and host rock types. 
The Froome underground mine started with initial ramp development in 2020, reaching initial stope production in early 2021 and commercial production in September 2021. Situated between 275 mL and 100 mL levels, its mining methods are longitudinal and transverse long hole mining with delayed backfill in a bottom-up sequence accessed from the footwall of the deposit. Mined material is trucked from each sublevel to surface, where it is hauled as run-of-mine 28 km by road trucks to the Fox-Stock mill site, and fed via a conveyor system to the mill’s crushing circuit.
The crushed product is transferred to a 1,500 tonne fine ore surge bin and then fed into a 2,000 tonnes per day grinding circuit, which includes two stages of closed circuit ball milling. Soluble gold is recovered by adsorption upon granular activated carbon in CIC, CIL, and CIP trains, with a process efficiency of up to 97%. Gold is removed from the carbon in a high temperature strip vessel in a closed circuit with electro-winning deposition. Gold plate is further refined by induction smelting and cast into molds