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Academic Lectures
Mining Weekly Seminar: Thursday, Oct. 3rd @4 pm| Wes Johnson
Department / Organization: Mining Engineering Department
Hecla’s Lucky Friday Mine improved safety and boosted production by 40% with the innovative Underhand Closed Bench method
Hecla’s Lucky Friday silver operation in Mullan, Idaho, currently stoping at approximately 2300m below ground surface, is one of the deepest mines in the western hemisphere. Until 2020, the mine was using an underhand cut and fill method to extract near-vertical, narrow silver-lead-zinc veins. Due to the heavily-faulted nature of the rock mass and great depth, mining-induced fault-slip seismicity posed a significant safety and production risk. Hecla has developed a new narrow-vein underhand longhole mining method termed “Underhand Closed Bench” or UCB mining. The intent of this method is to pro-actively trigger slip and seismicity on faults within close proximity to the stopes using large, down-dip longhole blasts. The method has been very successful, not only inducing virtually all seismic events with the blast, but also significantly reducing the overall seismic energy release and elimination, thus far, of damaging events. Also, the production at the mine is up significantly, with tonnage increasing over 40% since full implementation.
