Engineering & Mining Journal

MAR 2016

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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old methods. But experience has demon- strated that an air-compressor, to be suc- cessful and economical, must be self-gov- erning, for the reason that rock-drills, pumps, etc., that are run by compressed air are of necessity irregular in their action, so that the quantity of air used by them must vary…. The automatic mechanism is a part of the machine, and is always on hand to govern the compressor at all times and under all circumstances, and of course accomplishes in a month much saving of labor machinery and fuel. The machine throughout is strong and of excellent construction. It is built by the well- known Morris County Machine and Iron Company, at its mining machine-works in Dover, New Jersey. The Comet Crusher September 8, 1883—Crushers of the well- known Blake type, having a reciprocating action, do work only during a part of the time. The idea of so changing the design that work is continuous, naturally suggested itself, and it is to this class of machine that the Comet crusher belongs, the construction of which is shown in the accompanying engraving. In the jaw-crushers, the rock is broken by the approach of two planes sur- faces; in the Comet crusher, the planes are converted into circular surfaces, the recipro- cating being changed to the rotary motion of the inner crushing surface, which is mount- ed eccentrically on the shaft. The distance between a given point of the fixed outer sur- face and the rotating inner surface varies therefore during every revolution between the maximum and minimum. During one revolution, therefore, the rock between the two surfaces is once subjected to crushing action, which is thus continuous…. Messrs. Fraser & Chalmers of Chicago, who are the builders of the Comet crusher, attach the breaking head to the upright shaft by means of bolts, avoiding the use of zinc…. The crusher, of which five sizes are made has an excellent record for crushing material…The second drawing shows a design for an entire plant, the points of which will be readily understood. The Black Hills June 3, 1876—A pamphlet of 71 pages, now lying before us, contains Chapters V., VI., and VII. of the forthcoming Report of the exploration of the Black Hills of Dakota, made last year, under the direction of the Commissioners of Indian Affairs, by Walter P. Jenney, E.M. These chapters give an account of the general geology, mineral wealth, climate, and rainfall, and natural resources of the region…. …Mr. Jenney speaks favorably of the conditions for cheap mining, and of the prospects of a number of the districts; but his final conclusion is somewhat of a damper. He says: "There is gold enough to thoroughly settle and develop the country, and, after the placers are exhausted, stock- raising will be the great business of the inhabitants, who have a world of wealth in the splendid grazing of this region." This is damning with faint praise. Meanwhile, the present business of the inhabitants is saving their scalps from the Indians. Of course, we must approve the determination of the Government to pro- tect the lives of citizens, even though, by 64 E&MJ; • MARCH 2016 www.e-mj.com E & M J 1 5 0 Y E A R S Gyratory crushers, such as the Comet Crusher (above), enter the scene in the 1880s.

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