Identifier: emjengineeringmi110newy (find matches)
Title: E/MJ : engineering and mining journal
Year: 1920 (1920s)
Authors:
Subjects: Mineral industries Engineering
Publisher: New York : McGraw-Hill
Contributing Library: Engineering - University of Toronto
Digitizing Sponsor: University of Toronto

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or 86 lb. of rock to the tonof ore treated. With the pebble mill running in open circuit, deliv-ering a finished product, the practice developed of row of growing trees, starting from the original poles.Naturally, this wood is worthless as fuel or timber.In the older growth are scattered trees of superb hardwood and sufficient soft wood, as cedar and mahogany,for normal building purposes, but no new mine prospectcan depend on wood fuel in quantity to maintain aboiler plant of over 2.5 hp. Also, for mining work, thehard grades cannot be excelled for underground tim-bering, for shafts or drifts, but it would be unwise tocount on square-set sloping timbers, except as theymight be brought in from the lower coast savannapines. Naturally, hydro-electric power is the only solutionfor mining work, and it can be developed for al thedistricts if capital is invested. No development in depthcan be obtained to show mining stability without con-siderable power for hoisting, pumps, and compressors.
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)l- IKKSK.Vr .M11>1. AT LA I.TZ making a very wet discharge direct to the plates. Anexcess of water permitted a classification in the millthat held back the oversize. The second 8-ft. Hardinge mill was instaled in 1918for either open or closed circuit. This unit takes4-mesh product from the ten stamps, and, operating inclosed circuit with a 48-in. Akins classifier, the workis done at about eighty to ninety tons per twenty-fourhours on hard ore. At this point the stamps are oper-ating about to capacity, unless the ore can be crushedfiner than 2-in. to 2i-in. size; and the Akins classifierreturn to the Hardinge is about the limit of the classifierblades. Any greater tonnage would necessitate doublingthe classifiers, and doubtless require the use of steelpebbes in the Hardinge, with, of course, more powerconsumption. The mining districts of the east coast of Nicaraguaare all in tropical jungle. Growth is phenomenal. Alelephone line, built a few years ago, is now a continuous A vicious

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