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. 1903 Excerpt: ... to treat roasted ores by percolation, in the early days of the field, arose from the fact that the carbonate of limef present in the ore is converted into sulphate by roasting with the pyrites, if the roasting temperature does not exceed 5000 F. (2600 C), % and this anhydrous sulphate of lime when wetted forms plaster ...
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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. 1903 Excerpt: ... to treat roasted ores by percolation, in the early days of the field, arose from the fact that the carbonate of limef present in the ore is converted into sulphate by roasting with the pyrites, if the roasting temperature does not exceed 5000 F. (2600 C), % and this anhydrous sulphate of lime when wetted forms plaster-of-Paris, which causes the contents of the vats to swell, not only rendering percolation difficult, but, if left long enough exposed to this action, in some cases actually setting so hard as to require the use of wedges and even pickaxes to remove the tailings from the tanks; the usual method being to undercut, and pinch the blocks down. This hardening is said to have added fully 6d. per ton to the cost of discharging the vats. Prof. E. H. Liveing, A.R.S.M., has stated that at some works the soluble sails caused a consumption of 10 lb. of cyanide per ton of ore treated; and it may sometimes run even higher. t Mr. H. Knutsen observes that the finely crushed carbonate of iron with the carbonate of lime present in the ore, forms an "iron cement" which sets hard when wetted. Trans. Inst, of Mining and Metallurgy, of. at. X If heated to redness, it becomes denser, assumes a crystalline s ructure, and is said to lose the power of setting or solidifying. Elements of Chemistry, V. A. Miller, part ii. p. 469. To get over this difficulty, attempts were at first made, I believe, to slake the plaster-of-Paris, by transferring the roasted ore from the "coolers" to a "floor," where it was watered with hoses, and turned over several times, before putting it in the vats; but this required a great amount of labour, and was anything but satisfactory. The weak points of the Boulder Main Reef process are the cost of dry-crushing, roa...
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Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
