Mines and Methods Volume 1, No. 1 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 edition. Excerpt: ...side, but this left the pile slanting toward that side and necessitated leveling it off each time before drilling began. To avoid this the tapping drifts are driven from each side and the ore drawn off on both sides so that it keeps a fairly level surface for the men to work upon. Three manways, one at each end and one in the center of the side of the pillar having the raise in it, are carried up through the ore. These are made by blasting out a triangular notch in the pillar and cribbing it off on three sides. This manway is about 3x3 ft. in size and is merely large enough to allow a man to pass through it after the air pipe has been put in. The men climb the cribbing of split timber, a vertical pole being nailed to the cribbing for the men to hold to when climbing. These manways are carried up through the ore for only 50 ft., since at every 50 ft. a drift is driven to the stope from the three small manway raises in the pillar. The ore is drawn off in cars having a capacity of 28 cu. ft. and is run by two men to the main chutes. Only 4 or 5 men work in a stope, and one of these is busy all the time picking down the back of the room and the roofs of the different drifts in the pillar connecting with that room. The rooms are carried up until the ore becomes too poor to pay--at present when it carries about 1.45% copper. The room is then abandoned, and as soon as the stope on the other side of the pillar is completed, the air pipes and tracks in the raises and drifts in the pillar between the two stopes are removed. CAViNG THE ORE. As the area undermined by rooms increases, the roof gradually settles, hut as the top of the broken ore in the rooms is within six feet of the roof when the rooms are abandoned, the capping can not drop far. This...