Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers Volume 6

Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers Volume 6

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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. 1879 edition. Excerpt: ...passage of the pump and the men. The levels are always run so as to convey the water to a single sump at the foot of one of the shafts. The mines are not, however, very wet. For those of ordinary size, a small pump, working only part of a day, will keep the mine dry when the ground has not been affected by caves which let in the surface water. The method of mining is overhead-stoping, which is done by hand or compressed-air drills, according to the situation of the place to be worked. As soon as the mine is opened the rock is extracted at once, commencing from the shafts and winzes, working both sides of them. If the rock next the shaft does not contain copper it is left, but otherwise it is taken out. The roof must be then supported by timbers. No attempt is usually made to fill up the space left by what is taken out of the mine, unless the material to do it with is close at hand. In the bed called the " Ashbed," at the Copper Falls Mine, immense chambers, seventy-five feet square, have been left without any support of any kind. The roof itf very firm and has stood for many years, but there is no excuse for such methods, for eventually the roof must yield. The result in the Minnesota Mine is, that if the mine were pumped out there is little probability that it could be Worked. If pillars had been left, the mine would probably have still been capable of being put in working order. The result of the system is that that mine now can only be worked on a very small scale. There must come a time when the wooden props will crush, and then the future of the mine will be compromised, even-supposing that the shaft or level is kept in order. If a timber be replaced, it must be every time shorter, as the roof descends the surface-water is let in, ...show more

Product details

  • Paperback | 212 pages
  • 189 x 246 x 11mm | 386g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236588576
  • 9781236588579