Bulletin - United States Geological Survey Volume 525

Bulletin - United States Geological Survey Volume 525

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...to be supplied with complete equipment for approximately $1,600. (See PI. XX, A.) OPKN-CUT MINING. Open-cut methods of mining are applied where the ground is not more than 20 feet in depth. Open-cut work has one great advantage over drift mining in that artificial thawing is for the most part unnecessary, and where conditions are particularly favorable for the use of mechanical excavators it permits much more expeditious and efficient removal of the pay dirt at greatly reduced cost. Of the numerous modes of operation which may be grouped under this head four are practiced in the Fairbanks district; they differ in means by which the pay gravels are conveyed from the banks to the sluices--whether by direct shoveling or wheeling in barrows by hand, by groundsluicing, by hoisting with buckets on trolley carriers, or by steam, scrapers. (See fig. 9.) The first operation is always to clear the ground and strip off the barren overburden. This is accomplished (1) by groundsluicing in the early spring or preferably in the late fall, the material removed by groundsluicing being washed into the stream, or into a previously worked cut; (2) by scraping with horse scrapers, the material being FlgtTRE 9.--Dingrani showing iimiugi'ment of nn open-cut mine. carried to a spoil bank or dumped in an old cut; (3) by steam scraping. Some stripping is done by pick and wheelbarrow, but this is rather too expensive for general practice. Groundsluicing is always preferable where there is water and room for tailings. At several plants a combination of methods is employed. On Pedro Creek a company has taken over a block of productive gravels about 820 feet long and 450 feet wide, or containing nearly 350,000 square feet. The equipment instulled consists of a large...show more

Product details

  • Paperback | 94 pages
  • 189 x 246 x 5mm | 181g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236915003
  • 9781236915009