Pogo mine

The orebody consists of numerous highly irregular quartz veins, ranging in thickness from 2 to 40 ft (0.61 to 12.19 m) with 8 to 20 ft (2.4 to 6.1 m) being typical, and ranging in dip from horizontal to vertical with 30-45 degrees being normal. A complex system of faulting offsets the veins both parallel and perpendicular to the strike, resulting in a "chopped-up" orebody. Until 2019 the mine utilized drift-and-fill and overhand cut-and-fill mining methods when, under new owner Northern Star Resources, the mining method was changed to longhole stoping. Access to the orebody is via decline and spiral ramp. After blasting, ore is trucked to the central underground "ore bin", where it is then fed to a conveyor that takes it out of the mine directly to the mill. Typical daily production is about 2,500 tons of ore yielding approximately 1,000 troy ounces of gold.[4]

Pogo is notable for its paste backfill system, where 20% of the mine's tailings from which gold has been extracted are mixed with cement and then pumped back underground to support subsequent further excavation. This has the additional environmental benefit of reducing the amount of tailings that need to be stored on surface, minimizing the footprint of the mine's dry-stack tailings storage facility.[8]