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Underhand longwall program at Lucky Friday Mine, Mullan, ID.

Poad-ME; Johnson-G; Whyatt-JK; Hoskins-JR
Proceedings: Mechanics and Mitigation of Violent Failure in Coal and Hard-Rock Mines. Washington, DC: U.S. Bureau of Mines, 1995 May; :335-346
Researchers from the U.S. Bureau of Mines (USBM) have been investigating alternative mining methods to reduce the number and severity of mining-induced seismic events in the deep mines of the Coeur d'Alene Mining District of northern Idaho. In 1984, USBM entered into a three-way memorandum of agreement with Hecla Mining Co., Mullan, ID, and the University of Idaho, Moscow, ID, to design, implement, and evaluate a mining system that could be used safely and productively for vein mining in a rock-burst-prone mine. A mechanized underhand longwall cut-and-fill method using a ramp system for access was chosen for study at the Lucky Friday Mine, Mullan, ID. A 122-m (400-ft) long test stope was developed between the 5100 and 5300 levels. In the underhand method, a block of ground is mined from the top down in a single advancing face, always toward virgin ground; this procedure eliminates the development of a highly stressed sill pillar. Because an engineered fill is placed after each cut, a more competent back is created for the next cycle. Success of the test stope led to adoption of the underhand longwall as the primary mining method throughout the mine.
Mining-industry; Rock-falls; Rock-bursts; Rock-mechanics; Underground-mining; Control-technology; Geology; Geophysics; Engineering-controls; Ground-control; Ground-stability
Publication Date
Document Type
Book or book chapter
Maleki-H; Wopat-PF; Repsher-RC; Tuchman-RJ
Fiscal Year
NIOSH Division
Source Name
Proceedings: Mechanics and Mitigation of Violent Failure in Coal and Hard-Rock Mines
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division