. Steam shovel mining, including a consideration of electric shovels and other power excavators in open-pit mining . Fig. 27.—Stripping anthracite coal vein. coal remains. Upon this estimate depends its profitableness,as it has been undertaken primarily to form a final barrieragainst a fire that has been raging to the east of it for manyyears. The vein is 55 ft. thick and is on a 20° pitch. It has METHODS OF ATTACK 133. 134 STEAM SHOVEL MINING been robbed and re-robbed, and robbed again, but because ofits thickness and unhandy pitch, as well as the time of miningin the early 50s, it is thought
. Steam shovel mining, including a consideration of electric shovels and other power excavators in open-pit mining . Fig. 27.—Stripping anthracite coal vein. coal remains. Upon this estimate depends its profitableness,as it has been undertaken primarily to form a final barrieragainst a fire that has been raging to the east of it for manyyears. The vein is 55 ft. thick and is on a 20° pitch. It has METHODS OF ATTACK 133. 134 STEAM SHOVEL MINING been robbed and re-robbed, and robbed again, but because ofits thickness and unhandy pitch, as well as the time of miningin the early 50s, it is thought that not over 35 per cent, of thecoal has been extracted. Fig. 28 shows a plan of this stripping. In passing it may be mentioned that many of the open pitcoal mines have inclines leading from the pit bottom, or from theend of the haulage system, to the tops of tipples, from which thecoal is graded, cleaned, and loaded into standard gauge cars. Milling —The best condition for the applicationof the system of milling is believed to be where an orebody is ofmedium size suitable for stripping, but where it would not admitof economical locomotive haulage of the ore. The relative depthof overburden and ore, the space and facilities for trackage andapproaches and the relative outlay for equipment and develop-ment, are the determining factors for choosing between millingand shoveling. The advantages of the for
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1920
