【正文】 odernize and, if need be, redevelop the individual ponents of the face equipment for the demands of a high performance longwall. (I) These demands to achieve a high face output are summarized as follows: ? High coal output of the longwall machine with a power consumption up to 500 kW per drum ? Application of point attack bits with a necessary high bit cutting depth of 810 cm even by lower drum rotational speeds。英文原文 High performance longwall extraction in large depth amp。 large depth 1 INTRODUCTION The economic conditions for the German hardcoal mining industry have changed significantly in recent years. The German hardcoal industry had until the early 1990s a secure selling market. The ,Jahrhundertvertrag” guaranteed the purchase of German hardcoal by heavy industry and steel and energy providers. In the last few years the development of the European Union and a sweeping liberalization of the energy markets lead to heavy European and international rivalry. This increasing petition, caused by the import of inexpensive hardcoal from overseas, pressured the German hardcoal industry to react. It was necessary to concentrate the extraction on the most profitable collieries and to excavate only the most suitable parts of the deposits. Until recently it was required to mine the entire deposit. Although the number the mining operations decreased from 147 in 1990 to 64 in 1997 a 56 % decrease, the coal output decreased by only 32 % to 47 mu, tons. This concentration will continue. Additionally, a reduction of the costs of production and an increase in productivity required thedevelopment of new and innovative techniques and face equipment. The goal of these developments is to pensate for the petitive disadvantage due to the great depth of the German hardcoal deposits with the most modern technology and mining methods. Hard coal mining in Germany is based on a centuryold tradition. Figure 1 shows the German hardcoal basins. Even 500 years ago only the outcrop of the coal seams was mined. Since the midi 9th century, the Industrial Revolution and the resulting need for energy promoted the recovery of the deposits and the extraction in everincreasing depths. Since 1920 the average mining depth has increased from 330 m to 648 m in 1959 and lies today at 1,006 m (1997). Some longwaU operations have reached depths of around 1,450 m.. Figure 1: German hardcoal basins Figure 2: Sinking of the seambearing strata in the Ruhrarea in the northern direction An additional problem is the increasing coverage of the remaining hardcoal deposits. Figure 2 shows the sinking of the seambearing strata in the Ruhrarea in the northern direction. The new working areas and hardcoal mines, which open up the deposits in great depth, are attached without exception to the existing old coal mines. The main problem is to improve these existing mines, originally designed for much smaller working point capacity, to handle high performance longwall operations and to transport the entire conveyance discharge through the old mine to the coal preparation plant. 2 HIGH PERFORMANCE LONGWALL OPERATIONS In Germany the term “high performance longwall operation” is not clearly defined. Usually we describe it as the longwall which extract a amount of over 16,000 t high quality coal per day. That means 30,000 t runofmine coal per day. These operations can be roughly described by the following simple guidelines (1). ? Net production (effective delivery): Over 16,000 t high quality coal from great depths 1,000m ? Gross Production (total delivery): Up to times the production, ? 30,000 t runofmine coal/d ? Face length: Up to 480 m (600 m are planned) ? Power consumption: Up to 4,500 kW at the longwall ? Working length: Several kilometers ? Area increment of face advance: Over 16 m2/min up to 25 m2/min ? Supporting Performance: At least times the area increment of face advance, up to 30 m2/min ? Productivity in the longwall: Over 200 t (European record: 452 t ./MS in Ensdorf Colliery) ? Goaf treatment: Rooffall exploitation ? Development design: With parallel headings and inclines In order to integrate the high performance longwall operations in the existing collieries, it was necessary to carry out adaptation measures. The first measure was to optimize the development design and orientation of the new working areas and attached mines. Demands on the mine layout The great depth, in which the German hardcoal deposits lie, has a large influence on the mine layout. Each roadway must, therefore, be lined with extensive and expensive sliding roadway arch supports regardless if it is a main transport drift or only a shortterm parallel gate. The construction costs reach up to DM 15,000 ($US 9,000 ) per meter roadway. Attempts to replace the sliding roadway arch supports with bolted supports or to develop the roadway in a rectangular rather than arch profile, did not achieve all desired results to stabilize the roadway or reduce the development costs. The mine layout connected to the high performance longwall must fulfill the following requirements: Suitable infrastructure for the efficient transport of material to the longwall ? Short traveling time for the workers for a long effective working time ? Fast transport of workers with passenger lifts and belt riding ? Transport of large crosssections, for example transport of plete shield units ? Efficient material transport, maximal 3 h from storage depot over the surface to the longwall Suitable infrastructure for product extraction: ? Sufficient dimensional analysis of the belt conveyor ? If possible, inclines to avoid vertical conveyance ? If necessary, storage bunkers for homogenization of the conveyance discharge Adequate ventilation area ? Control of the climatic c