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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disobedience to express proclamation, they may have forfeited their claim to protec- tion. But we think the blood that has been, and will be, shed in this affair too great a price for the booty sought; and we trust the follies of the past will not be crowned with an expensive purchase of the Indian right to the Black Hills. A little more than a year later, E&MJ; would report that 725 stamps, four arastras and a smelter are operating in the Black Hills. These mills are located in the upper towns of the main gulch from Grayville west, at Lead City, Pennington, Strawberry Gulch and the smelter at Galena. They pro- vide updates on about a dozen mines work- ing the Black Hills gulches . Gold Mining and Processing In a September 4, 1886, contribution, Cost of Mining and Milling Free Gold Ores, Hamilton Smith Jr. provides insight about the activity at American gold mines at the time . The gold from all the mines for which the following comparisons are made is obtained nearly altogether by the simplest methods of amalgamation and concentration. The ore coming from the mines is first passed over grizzlies: the larger pieces of rock that do not drop through the grizzlies are then crushed by rock-breakers into small fragments. The fine ore is then fed to the stamp mills, which consist of batteries each having five stamp- heads dropping in a cast-iron mortar. Electro-plated sheets of copper are general- ly placed inside these mortars, into which quicksilver is introduced. A sufficient supply of water is constantly poured into the mor- tar. The finely crushed ore and amalgam are discharged from the side of the mortar through finely punched or slotted screens of sheet-iron, and the escaping "pulp" passes down in a thin sheet through inclined sluices over sheets of copper also silver plat- ed. The tailings flowing from the sluices are in some cases passed over rough blankets, or through buddles or vanners, in order to concentrate and save the heavy particles of either amalgam or pyrites. In all the reduc- tion-works that will be spoken of, by far the larger portion of gold is obtained in the mor- tars and on the copper plates…. California—The Sierra Buttes and Plumas-Eureka mines are situated some 35 miles by wagon-road from the Central Pacific Railroad. Wood for timber and fuel is abundant and cheap. Mining labor costs about $2.50 a day. Water-power is used for crushing at the Sierra Buttes; at the Plumas Eureka, both water and steam are used. The lodes worked are of good size, averaging a thickness of perhaps 8 feet, and are reached by ad1t levels. At Sierra Buttes, 93 stamps were run- ning for first six months and 60 stamps for last six months, being an average of 76.5 stamps; 54,479 tons mined, yielding $380,145, or $6.98 a ton. The Sierra Buttes and Plumas-Eureka Mines are owned by English corporations under the same general management, and have been operated in a very judicious and economical manner; in these respects, their management compares most favorably with that of other foreign mines owned in England. Dakota—The Homestake, Father de Smet, and Caledonia mines are situated near the town of Deadwood, a distance of some 250 miles from the Union Pacific Railroad. A branch of the Chicago & Northwestern road has in the last two or three years been approaching Deadwood, thus diminishing the length of wagon trans- portation; this branch will reach the town some time during the present year. Wood for fuel and timbers is brought to the mine by means of a narrow-gauge railroad, a dis- tance of 15 or 20 miles. Water for mill pur- poses is more than usually expensive. MARCH 2016 • E&MJ; 65 www.e-mj.com E & M J 1 5 0 Y E A R S www.normet.com FOR TOUGH JOBS UNDERGROUND Expertise in customer processes: > Ground Support - Lateral & Shaft · Sprayed concrete · Scaling · Surface support liner · Ground consolidation · Bolting > Explosives Charging > Caving Hangup Removal > Equipment Life Cycle Management > Lining > Groundwater Control > Wa terproofing > Services Installations > Life Time Care > Backfill Come and visit us at Bauma 2016 Hall B3. 249