Transactions of the American Institute of Mining Engineers Volume 26

Transactions of the American Institute of Mining Engineers Volume 26

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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. 1897 edition. Excerpt: ...on what is known as the Rainbow lode, and that of the Lexington, Blue Bird, Nettie, Burlington and other mines. The gangue is quartz, carrying pyrite, sphalerite, galenite, tetrahedrite and argentite, with manganese in the form of rhodochrosite and rhodonite. Good results on ores of this class cannot be obtained by concentration, because large percentages of the silver-bearing minerals are disseminated through the gangue in such minute grains that even the finest practicable crushing does not liberate them from the quartz so that a good saving can be effected. Furthermore, a great loss is sustained from the floating away of the rich silver-glance in the form of a greasy scum upon the surface of the water. Nearly all of these ores are therefore treated by chloridizing-roasting and amalgamation, at a cost of from $5.50 to $7.50 per ton, and with a saving of about 85 to 90 per cent, of the silver and 40 per cent, of the gold; the fineness of the resulting bullion being from.400 to.700. The " Combination Process," that is, wet crushing followed by concentration and the treatment of the tailings from the concentrating-machines in amalgamating-pans, has never been tried on these ores on a large scale. This method of treatment has its advocates, who claim that lower cost of treatment, increased saving of gold contents, together with the probability of securing finer bullion, would more than offset the loss in smelting the concentrates and the smelting-charges; but, judging from runs of these silver-ores which have been made through the concentrating-mills, it is very doubtful if a good saving could be made in the pans, because, while the silver sulphides which would escape over the concentrating-machines might be decomposed more

Product details

  • Paperback
  • 189 x 246 x 19mm | 649g
  • United States
  • English
  • black & white illustrations
  • 1236980131
  • 9781236980137