1、英文原文 High performance longwall extraction in large depth H.C.WKnissel & H. Mischo Technical University of Clausthal, Institute for Mining, Clausthal-Zellerfeld, Germany ABSTRACT: Stagnation of coal prices to a low level on the international coal trading markets reduces profits and pressured the Germ
2、an hardcoal companies to reduce the mining costs by increasing of the face output and at the same time by reducing the numbers of working points. This concentration could be achieved by the insertion of high performance longwall operations. The success of longwall operations is.dependent upon key po
3、ints like Geology, equipment and the mine layout. This paper discusses the definition of high performance longwall extraction in large depths and introduces the standard parameters of the equipment and the typical coefficients of these longwall operations as well. Keywords: high performance； longwal
4、l； 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 indus
5、try 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 competition, caused by the import of inexpensive hardcoal from overseas, pressured the
6、 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 i
7、n 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
8、 these developments is to compensate for the competitive 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 century-old tradition. Figure 1 shows the German hardcoal basins. Even 500 years
9、ago only the out-crop of thecoal seams was mined. Since the mid-i 9th century, the Industrial Revolution and the resulting need for energy promoted the recovery of the deposits and the extraction in ever-increasing depths. Since 1920 the average mining depth has increased from330 m to 648 m in 1959
10、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 seam-bearing strata in the Ruhr-area in the northern direction An additional problem is the increasing coverage of the remaining hardcoal deposit
11、s. Figure 2 shows the sinking of the seam-bearing strata in the Ruhr-area 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
12、, 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. 2HIGH PERFORMANCE LONGWALL OPERATIONS In Germany the term “high performance longwall oper
13、ation” is not clearly defined. Usually we describe it as the longwall which extract a net amount of over 16,000 t high quality coal per day. That means 30,000 t run-of-mine coal per day. These operations can be roughly described by the following simple guidelines (1). Net production (effective deliv
14、ery): Over 16,000 thigh quality coal from great depths 1,000m Gross Production (total delivery): Up to 1.6 times the net production, 30,000 t run-of-mine 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 incr
15、ement of face advance: Over 16 m2/min up to 25 m2/min Supporting Performance: At least 1.2 times the area increment of face advance, up to 30 m2/min Productivity in the longwall: Over 200 t v.F.IMS (European record: 452 t v.F./MS in Ensdorf Colliery) Goaf treatment: Roof-fall exploitation Developmen
16、t 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 m
17、ines. 2.1 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 short-term 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
