Narrow vein mining 1 - steep veins

摘要

Narrow vein mining is as old as M underground mining itself. Many centuries after it was first used, it was the method chiefly described in Georgius Agricola's 1556 De Re Metallica. In the Third Edition of Peele's Mining Engineer's Handbook well over 50 pages of the section on underground mining are devoted to the working of narrow veins. The methods described there included both underhand and overhand open stopes with timber supports, shrinkage stoping, cut-and-fill and reusing. In certain circumstances, all these methods are still in use. The terminology allows flexibility, but in this part of the article narrow vein mining is considered to be the working of mineral deposits which are typically no more than 2-3m wide, and are for the most part steeply inclined, with dips exceeding 50-55 deg (an angle at which broken ore may be expected to flow). Historically, narrow vein mining has been labour intensive. The equipment, methods and materials used have included hand-held air-leg drills, still timber supports, scraper winches, draw chutes or rail-mounted loaders, and hand tramping on rail tracks. These methods are comparatively low in capital cost, and thus might be appropriate for a very small-scale operation, but generally the operating costs are high and many orebodies, on this account, have been considered uneconomic.