Mining

Cut and fill mining
Cut-and-fill mining is applied to mining steeply dipping orebodies, in strata with good to moderate stability, and a comparatively high-grade mineralization. It provides betterselectivity than SLOS and VCR mining, and is preferred for orebodies with irregular shape and scattered mineralization, where high grade sections can be mined separately, and low grade rock left in thestopes. However, men and machines are working within the stope, which detracts from the safety of the operation. Cut-and-fill mining excavates the ore in horizontal slices, starting from a bottomundercut, advancing upward. The ore is drilled, blasted, loaded and removed from the stope, which is then backfilled with deslimed sand tailings from the dressing plant, or waste rock carried in by LHDfrom development drives. The fill serves both to support stope walls, and as a working platform when mining the next slice. Before filling, stope entries are barricaded and drainage tubes installed.The stope is then filled with sand to almost full height, and cement is mixed into the final pours, to provide a solid floor for mobile machines to operate. As no rib pillars are left, and the crownpillar is commonly taken out in a single large blast once sufficient expansion room is available, most of the ore can be recovered with a minimum of waste dilution. Development for cut-and-fill miningincludes: a footwall haulage drive along the orebody at the main level; an undercut of the stope area, with drains for water; a spiral ramp in the footwall, with access drive to the undercut; and araise connection to the level above, for ventilation and filling material. The stope face appears as a wall, with an open slot at the bottom, above the fill. Breasting holes are drilled by a rig, chargedand blasted, with the slot underneath providing swell space for the blasted rock. The mineralization shows in the stope face, where it can be inspected by geologists. The drill pattern can be...