Mining Engineers' Handbook, Volume 1Robert Peele, John Adams Church J. Wiley & sons, Incorporated, 1941 |
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Halaman 10-136
... pillars under the protection of concrete pillars ( Fig 181 ) built and located with care near the pillars to be removed . Bottom of concrete pillar has a diam that permits tapering to a min of 8 ft . Base of pillar is doweled to floor ...
... pillars under the protection of concrete pillars ( Fig 181 ) built and located with care near the pillars to be removed . Bottom of concrete pillar has a diam that permits tapering to a min of 8 ft . Base of pillar is doweled to floor ...
Halaman 10-503
... pillar , much of the coal being blasted into the central empty breast . Small pillars P are left between skip manways and full breasts ; they are drilled and blasted after the skips are completed ( 609 ) . ( C ) Pillar - chute method ...
... pillar , much of the coal being blasted into the central empty breast . Small pillars P are left between skip manways and full breasts ; they are drilled and blasted after the skips are completed ( 609 ) . ( C ) Pillar - chute method ...
Halaman 10-530
... pillars be left , the surface is unaffected ; the mesh of the network of pillars and working places should be smaller as workings are shallower . As depth increases , workings can be enlarged in proportion to area of pillars , provided ...
... pillars be left , the surface is unaffected ; the mesh of the network of pillars and working places should be smaller as workings are shallower . As depth increases , workings can be enlarged in proportion to area of pillars , provided ...
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angle Ariz aver bench black powder blasting block bottom broken caps cars caving chalcocite chalcopyrite churn drills chutes coal copper core cost per ft cribbed cross-sec crosscuts crystals Data deposits depth diam driven dynamite excavation explosives face filled stopes floor footwall ft deep ft high ft long ft wide fuse gelatin grizzly ground hammer drills hanging wall haulage level hematite hoisting holes horiz igneous rocks inclined intervals iron jackhammers labor lagging limestone loading magnetite manway Mesabi Range method minerals mining mucking orebody pillars pipe porphyry posts powder pump pyrite pyrrhotite quartz quartzite raises rock rods samples sand schist scraper sets shift shovel shrinkage stopes side sill sinking slice sludge soft sphalerite square-set steel stope stulls sub-level sulphide surface Table thick timber tons top-slicing Total tunnel usually veins ventilation waste width