METHOD OF COMBINED OPEN-CUT AND UNDERGROUND STEEPLY PITCHING DEPOSIT DEVELOPMENT Russian patent published in 2006 - IPC E21C41/00 

FIELD: mining, particularly to develop mineral deposits formed by permafrost rock and column-shaped ore bodies.

SUBSTANCE: method involves cutting ore body by open-cut mining up to design mark reaching and by open-cut and underground mining up to underground mining mark reaching. During open-cut mining ore body is exposed by inner and outer haulage bench system. During open-cut mining ore is cut by underground excavations in combination with haulage benches. Open-cut works during open-cut mining are carried out with lag interval in vertical direction from underground work equal to not less than working ledge height. Ore located in central ore body part is cut in layers in several steps by blasting down-holes. Ore located in formation-screened ore body part is cut by ascending ring bores drilled from underground excavations. To perform open-cut and underground development recovering excavation is formed in formation-screened ore body part in working pit zone by blasting ring bores drilled from underground excavations. The recovering excavation is expanded in proportion to opened mine work descending by blasting vertical wells at each working step so that subdrilling depth is not less than 1/3 of working step height.

EFFECT: increased efficiency of mine works during ore body cutting below design pit bottom mark.

1 tbl, 11 dwg