采矿英语第四章.docVIP

Unit 4 Underground Mine Development System 地下采矿开拓系统 4.1 Underground Mine Development 开拓掘进 Primary and secondary horizontal openings play a major role in the development of a mine. This is well documented in statistics showing that out of the total length of development openings driven in 1980，82% were horizontal openings, 16% were raises, and the rest were shafts, slopes, etc. The Fig. 4.1 has showed the underground mining system. Fig. 4.1 Underground mining terms Horizontal openings for primary development are applicable for mineral deposits in mountainous terrain. The deposit can be an outcropping (coal seam) or one that can be reached most conveniently by a horizontal tunnel (adit or drift) nearby. The cross-sectional area of the opening，as in the case of shafts and slopes (declines)， must accommodate all required services for the mine. To meet large production and ventilation requirements, a cross section of large size is required. An alternative is the use of multiple openings，customary in coal mines. The shape of the cross section of the opening may vary from rectangular (in outcropping seam deposits such as coal) to any convenient shape ( horseshoe，round) as dictated by ground conditions， construction technology, and required services of the capital opening. Secondary development openings can be driven within the deposit, as is the practice in flat-lying coal seams (e. g. drifts, entries, crosscuts)，or outside the deposit, as is generally practiced in three-dimensional ore bodies in metal mines (c. g. adits，tunnels， drifts). In the case of coal mines, there is no difference between secondary development and the production openings. The only difference is in the number of parallel entries, which can vary from seven to eleven mains and usually five to seven submains. The number of entries depends mainly on ventilation and haulage needs. 1 ? Technology of Construction Two major systems are in general use ：① the drill-and-blast method，and ?mechanical systems with