采礦外文翻譯---極深條件下的高效長壁采煤

1、<p><b>　　英文原文</b></p><p>　　High performance longwall extraction in large depth</p><p>　　H.C.WKnissel & H. Mischo</p><p>　　Technical University of Clausthal, Ins

2、titute for Mining, Clausthal-Zellerfeld, Germany</p><p>　　ABSTRACT: Stagnation of coal prices to a low level on the international coal trading markets reduces profits and pressured the German hardcoal compan

3、ies 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 operation

4、s.</p><p>　　The success of longwall operations is.dependent upon key points like Geology, equipment and the mine layout. This paper discusses the definition of high performance longwall extraction in large d

5、epths and introduces the standard parameters of the equipment and the typical coefficients of these longwall operations as well.</p><p>　　Keywords: high performance; longwall; large depth</p><p>

6、;　　1 INTRODUCTION</p><p>　　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

7、 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

8、 the energy markets lead to heavy European and international rivalry. This increasing competition, ca</p><p>　　Hard coal mining in Germany is based on a century-old tradition. Figure 1 shows the German hardc

9、oal basins.</p><p>　　Even 500 years ago only the out-crop of the coal seams was mined. Since the mid-i 9th century, the Industrial Revolution and the resulting need for energy promoted the recovery of the de

10、posits and the extraction in ever-increasing 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

11、,450 m..</p><p>　　Figure 1: German hardcoal basins</p><p>　　Figure 2: Sinking of the seam-bearing strata in the Ruhr-area in the northern direction</p><p>　　An additional problem is

12、 the increasing coverage of the remaining hardcoal deposits. Figure 2 shows the sinking of the seam-bearing strata in the Ruhr-area in the northern direction.</p><p>　　The new working areas and hardcoal mine

13、s, 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 capacit

14、y, to handle high performance longwall operations and to transport the entire conveyance discharge through the old mine to the coal preparation plant.</p><p>　　2 HIGH PERFORMANCE LONGWALL OPERATIONS</p&g

15、t;<p>　　In Germany the term “high performance longwall operation” 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

16、,000 t run-of-mine coal per day. These operations can be roughly described by the following simple guidelines (1).</p><p>　　? Net production (effective delivery):</p><p>　　Over 16,000 t high qua

17、lity coal from great depths> 1,000m</p><p>　　? Gross Production (total delivery):</p><p>　　Up to 1.6 times the net production,</p><p>　　? 30,000 t run-of-mine coal/d</p>&

18、lt;p>　　? Face length:</p><p>　　Up to 480 m (600 m are planned)</p><p>　　? Power consumption:</p><p>　　Up to 4,500 kW at the longwall</p><p>　　? Working length:</p

19、><p>　　Several kilometers</p><p>　　? Area increment of face advance:</p><p>　　Over 16 m2/min up to 25 m2/min</p><p>　　? Supporting Performance:</p><p>　　At le

20、ast 1.2 times the area increment of face advance, up to 30 m2/min</p><p>　　? Productivity in the longwall:</p><p>　　Over 200 t v.F.IMS (European record: 452 t v.F./MS in Ensdorf Colliery)</p&

21、gt;<p>　　? Goaf treatment:</p><p>　　Roof-fall exploitation</p><p>　　? Development design:</p><p>　　With parallel headings and inclines</p><p>　　In order to integ

22、rate 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 are

23、as and attached mines.</p><p>　　2.1 Demands on the mine layout</p><p>　　The great depth, in which the German hardcoal deposits lie, has a large influence on the mine layout. Each roadway must,

24、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

25、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, </p><p>　　The mine layout connected to the high

26、performance longwall must fulfill the following requirements:</p><p>　　- Suitable infrastructure for the efficient transport of material to the longwall</p><p>　　? Short traveling time for the w

27、orkers for a long effective working time</p><p>　　? Fast transport of workers with passenger lifts and belt riding</p><p>　　? Transport of large cross-sections, for example transport of complete

28、 shield units</p><p>　　? Efficient material transport, maximal 3 h from storage depot over the surface to the longwall</p><p>　　- Suitable infrastructure for product extraction:</p><p

29、>　　? Sufficient dimensional analysis of the belt conveyor</p><p>　　? If possible, inclines to avoid vertical conveyance</p><p>　　? If necessary, storage bunkers for homogenization of the conv

30、eyance discharge</p><p>　　- Adequate ventilation area</p><p>　　? Control of the climatic conditions, for example formation and mining product temperature, waste heat of the mining machinery</

31、p><p>　　? Control of the gas emission</p><p>　　- Adequate energy supply</p><p>　　? Electrical energy</p><p>　　? Compressed air and hydraulics</p><p>　　? Water

32、 for cooling water, consolidation and nozzle reception</p><p>　　? Cooling capacity and air conditioning</p><p>　　Since the above-mentioned requirements were, in many cases, taken into considerat

33、ion in the planning and development of new fields and connecting mines, they are capable of economical and trouble-free high performance longwall operations today.</p><p>　　dust consolidation and nozzle rece

34、ption</p><p>　　? Cooling capacity and air conditioning</p><p>　　Since the above-mentioned requirements were, in many cases, taken into consideration in the planning and development of new fields

35、 and connecting mines, they are capable of economical and trouble-free high performance longwall operations today.</p><p>　　2.2 Connection of the high performance longwall to the mining layout</p>&l

36、t;p>　　The layout of the fields and the connection of the longwall operations to the mining layout is intimately associated with the development of the mining layout itself. The following requirements should, therefore

37、, be considered (1):</p><p>　　- Development of the connecting mine and the working areas in the coal seam with inclines even in great depth</p><p>　　? Delivery with belt conveyors: no junctions

38、from horizontal to vertical haulage</p><p>　　? No junctions from horizontal to vertical haulage in transport and carriage roads</p><p>　　- Parallel headings should be directly connected with a m

39、ain deliveiy or transport road if possible</p><p>　　? Linear product extraction from the longwall</p><p>　　? Faster material transport to the longwall, reduction of the transport time</p>

40、<p>　　? Short travelling time, extension of the effective working time</p><p>　　? Short ventilation circuits</p><p>　　Under certain circumstances a homogenization of the conveyance dischar

41、ge may be necessary. In particular for the continuous operation of the small belt conveyors in the old parts of the mines and a continuous preparation in particular, a homogenous conveyance discharge is necessary.</p&

42、gt;<p>　　2.3 Design of the longwall</p><p>　　In order to operate high performance longwalls under the difficult geologic and climatic conditions prevalent in depths greater than 1,000 meters, aspecia

43、l longwall design is needed. These longwalLs are generally cut as retreating faces to the main haulage road. This has the advantage of obtaining information about the seam, for example coal gas content, before starting t

44、he excavation.</p><p>　　With gas rich longwalls, in particular, a preliminary degassing can be undertaken before the extraction begins. Due to the high overburden pressure at great depths, a significant expe

45、nditure is necessary to prepare and maintain the parallel extraction and transport roads. To limit this expenditure the parallel gates are abandoned after passage of the face. There are no coordination problems between t

46、he longwall operation and the drifting as well, and there is no additional material handling in t</p><p>　　Until the early l990s face lengths of only up to 270 m were technically possible and allowed at grea

47、t depths. Today the new high performance longwalls are designed as double longwall systems with two 350 m face lengths or as single longwalls with up to</p><p>　　480 m face lengths. Greater face lengths are

48、not practical at this time because the layout of the face conveyor reaches its limits. At present the length of the face conveyor and the resulting vibrations create significant problems for durability. The maximal possi

49、ble power consumption of the face conveyor limits the loading rate and, therewith, the total length of the face conveyor length of the escape way exceeds the regulated length. Another significant problem is the air cooli

50、ng.</p><p>　　The maximal seam pitch in the longwall is generally reported to be 40 gon. Steeper deposit sections are not suitable for economically profitable recovery using standing high performance longwall

51、 techniques. A gently declining mining direction through the strike has proven to be useful in increasing the stability of the wall and avoiding the flaking of the seam through the tipped coal face.</p><p>　

52、　2.4 Safety Regulations</p><p>　　Due to the slow escape speeds in the longwall, a long face increases the duration of a possible escape over the acceptable and allowed limits. In order to confront this prob

53、lem several measures were implemented. Care was taken when selecting and constructing the individualshield supports in order to attain comfortable and sufficiently wide gangway. In addition it became necessary to equip t

54、he face workers with the most modern filter self-rescuers. These filter self-rescuers guarantee lower inhal</p><p>　　The introduction of high performance longwall operations and the planning of overly long f

55、aces also creates new problems for explosion protection. The German hardcoal mining industry requires the erection of explosion water barriers with 200 1 water/rn2 roadway cross-section at 400 m intervals to extinguish t

56、he beginnings of methane gas explosions. These requirements are clearly exceeded by the introduced great face lengths with a distance of up to 120 m from the face end to the nearest barrier.</p><p>　　Figure

57、3：GROUTING side packs and flue dust insertion piping for the prevention of air leakage in the abandoned workings</p><p>　　grouting side packs and piping of flue dust against this grouting side pack. The goal

58、 is to reduce air leakage and to avoid the formation of an explosive gas mixture behind the shield column. Figure 3 shows the arrangement of the grouting side packs and flue dust in the abandoned workings.</p><

59、;p>　　In order to limit the starting length of a methane explosion, a mobile explosion water barrier (Saar-Ex 2000) was developed. This system is based on the active Tremonia barriers which, sensor-controlled, produce

60、and distribute a fine water mist throughout the roadway cross section before the explosion wave can continue. This</p><p>　　Saar-Ex 2000 explosion water barrier reduces the distance fromthe face end to the f

61、irst barrier to a constant 30 m.</p><p>　　2.5 New developments of longwall techniques</p><p>　　The desired high face output could not be achieved using the formerly applied face equipment. It w

62、as, therefore, necessary to modernize and, if need be, redevelop the individual components of the face equipment for the demands of a high performance longwall. (I)</p><p>　　These demands to achieve a high f

63、ace output are summarized as follows:</p><p>　　? High coal output of the longwall machine with a power consumption up to 500 kW per drum</p><p>　　? Application of point attack bits with a necess

64、ary high bit cutting depth of 8-10 cm even by lower drum rotational speeds; this is necessary for an effective reduction of the dust production</p><p>　　? Effective pie track flushing to avoid Hot-Spots and

65、to consolidate the dust。</p><p>　　? Large drum cutting depth, up to 1,000 mm</p><p>　　? Optimized drum loading capacity by the use of cowls and Globoid-drums</p><p>　　? High winning

66、 speed, speed over 13 mlmin needs a powerful wheel-rackatrack haulage system</p><p>　　? High technical availability</p><p>　　The shearer loaders SL from the company Eickhoff which fulfill the ab

67、ove-mentioned criteria, are most commonly used in German high performance longwall operations. It was then necessary to switch from the previously used I kVtechnology in the longwall, present in most mines, to a 3 or 5 k

68、V power supply. Figure 4 shows a shearer loader SL.</p><p>　　The armored flexible face conveyors in the longwall area were equipped to reach high chain speed and manage large loaded cross sections in order t

69、o handle the expected increase in tonnage.</p><p>　　Much effort has been placed in ?the face support in order to continue the development of the longwall technique. The newly developed two-leg lemniscate pow

70、ered face supports are used today without exception with the IFS (immediate forward support). The yield support resistances are suited for the high demands of great depths and amount up to 5,700 kN (yield load density of

71、 600 kN/m2). An additional demand on the shield support was the necessity for high supporting performance of up to 30 m2/min </p><p>　　In order to optimize the longwall face move, the transport dimensions an

72、d weight were limited to make complete transport under ground possible. Within the framework of the new developments in longwall techniques, the system width was increased from the customary spacing of 1.50 m to 1.75 m f

73、or the longwall conveyor as well as the shield support. This enlargement of the system width primarily serves the purpose of minimizing the number of possible trouble sources in the longwall.</p><p>　　An ana

74、lysis in the late-eighties and nineties showed that great expenditure was required to control the face-end zone and the belt entry. It was not possible to use the common face suport in the parallel mining roadways due to

75、 the lining of the mining parallel headings with TH-sliding roadway arches. Moreover, several meters between the parallel mining roadway and the first shield had to be built up conventionally using single legs and strike

76、 beams. Only after the development of the new face end</p><p>　　Figure 4: Shearer loader SL from Eickhoff</p><p>　　To control the longwall face-end it was necessary to develop new power support

77、systems as seen above. There was, however, no need for new side discharge technology. The direct side discharges used in the Ruhr area and the free side discharges with discharge pan used in the Saar area were able to ha

78、ndle even the great output of high performance longwalls.</p><p>　　The DSK (Deutsche Steinkohle AG) has realized the above-mentioned concept in different high performance longwall operations. One of these op

79、erations is described below.</p><p>　　3 HIGH PERFORMANCE LONGWALL EXTRACTION “LONG WALL 2000” AT THE ENSDORF COLLIERY</p><p>　　The Ensdorf colliery was one of the first to introduce high perfor

80、mance longwall operations to the German hardcoal mining industry in 1995 under the concept “Longwall 2000”. The goal of this trial was to install a longwall system that could guarantee the daily output of 12,000 t of the

81、 Ensdorf mine out of a single longwall. Based on the positive results, the idea was then taken over by the other mines in the Saar deposit.</p><p>　　The Ensdorf colliery mines the northem section of the Saar

82、 hardcoal deposit on the Schwalbach coal seam (Coal seam 930) and the Wahlschied coal seam (Coal seam 950). The underlying Grangeleisen coal seam (Coal seam 970) is developed as a reserve. The mining done in this collier

83、y, formed from the formerly independent Griesborn, Schwalbach and Ensdorf mines, concentrated on the southern deposits in shallow depths up to the 1950s. The mine concessions Ostfeld and Nordfeld were also mined later. B

84、ec</p><p>　　As can be seen in Figure 5, the Dilsburg field is developed with centered inclines and cross-cuts. The parallel mining headings are directly connected with the inclining main haulage roads. These

85、 transport requirements were ideally met using a suitable infrastructure for material transport and haulage. Both are processed over the Nordschacht. Using a powerful shaft haulage layout it was possible to transport com

86、plete shield units and machinery up to 35 tons, or up to 160 persons per haul. The tr</p><p>　　The material transport is processed over the 18th level. The pieces to be transported are transferred directly f

87、rom the cage to the transport site using locomotive haulage. At this point the material is transferred to the flat top track cable ways which carries it to the longwall. These track cable ways can also be used for face m

88、oves and transport up to 3 complete shield units at a time. Ideally the material transport from the storage depot on the surface to the longwall can be completed in 2 h</p><p>　　The product transport from th

89、e parallel gate continues on the conveyor belts in the inclines. Using additional conveyor belts, the raw coal is raised to the 14th level and carried over a lateral road on the 14th level to the old Duhamel Collieiy. Th

90、ere it is raised through the Barbara drift over a length of 3.500 m and a vertical interval of 650 m to the surface. The material is then processed by the Duhamel shaft plant. Due to the generous design of the conveyor b

91、elts, at least 1,400 mm wide an</p><p>　　Since the energy supply of the Dilsburg field comes through the Nordschacht, it was no problem to hang up the additional 5 kV lines needed for the high performance lo

92、ngwalls in the shaft.</p><p>　　When planning the layout of the high performance longwalls, the double longwall systems tried and proved in Ensdorf were used. Figure 7 shows the layout for the first double lo

93、ngwall using the high performance longwall technique. It ran from the beginning of 1996 to the middle of 1997.</p><p>　　When using the double longwall system, two longwall operations in neighboring panels ar

94、e run simultaneously, using the same center gate. Both longwalls are layed out as retreating faces to the coal seam. The upper longwall hauls over the center gate, which also serves for ventilation and the lower longwall

95、 hauls over lower gate. The face length of the individual longwalls is 310 m, the panel length around 2,850 m. The direction of face advance is slightly inclined out of the drift into the dip i</p><p>　　Figu

96、re 5: Mine plan of the Ensdorf colliery</p><p>　　Figure 6: Vertical section of the Ensdorf colliery</p><p>　　Figure 7: Layout of the high performance longwall in the Ensdorf colliery</p>

97、<p>　　The Eickhoff SL 500 is used as the standard shearer loader. Figure 8 shows this shearer with labeled transport units.</p><p>　　A total performance of 1,240 kW was installed in this shearer loader.

98、 Each drum has 500 kW (5kV) and each of the two winches has 60 kW (1kV) to its disposal. With a maximal speed of 13 mlmin during the extraction and a cutting depth of up to 1,000 nun for both Globoid drums, up to 39 m3 c

99、oal per minute can be extracted from a 3 m thick coal seam.</p><p>　　To be able to extract these amount, a armored face chain conveyor RB 1000 280 V with a engagement width of 1,000 mm and a maximal drive po

100、wer of 615 kW was installed in the longwall. The chain speed of the 34 x 102 double center chain can be increased to up to 1.61 mIs. In this case the speed had previously been restricted to 0.93 m/s. It was necessary to