1、翻译部分英文原文Study on Critical, Modern Technology forMining in Gassy Deep MinesYUAN LiangHuainan Mining (Group) Co. Ltd., Huainan, Anhui 232001, ChinaAbstract: To achieve safe and highly efficient mining in the gassy, deep mines of the Huainan collieries simultaneous coal and gas extraction, and the corr
2、esponding ventilation methods were developed. This includes a set of mining procedures and principles which help insure safe and efficient production. Furthermore, green mining, meaning the comprehensive use of emitted gas, proper treatment of the environment and appropriate mine temperature control
3、, is now standard. The concepts of modern mining and the principles of pressure relief are described. Coal-gas simultaneous extraction and multi-pressure relief techniques were developed which require a combination of surface and underground gas extraction. The application of Y-ventilation systems,
4、of roadways retained along goafs, of stress control techniques for highly fragile mine roofs and of powerful, automatic and reliable mining equipment contributes to safe operation of modern deep mines. Operating parameters for these techniques are described and the results of their use discussed.Key
5、 words: gassy deep mining; modern mining; coal and gas simultaneous extraction; green miningCLC number: TD 821 IntroductionTypical in terms of gassy mines in China, the Huainan mine areas have coal reserves of 50 billion tons and gas reserves of 5.928 billion m3. The coal seam is characterized as ri
6、ch in gas content (1226 m3/t), deeply buried (3001500 m), extremely soft in texture (f = 0.20.8), low in permeability ( =0.0011 m2/(MPa2d) and high in gas pressure (Pmax=6 MPa). Ten production mines, with a gas emission rate of 820 m3/min, are all considered gassy mines. The area is geologically com
7、plicated. Where multiple gassy coal seam groups are being worked, however, the bursting risk becomes high when working at depth. Highpressure soft rocks surround the seam: the horizontal stress normally is 1.11.5 times the vertical stress. Furthermore, over 80% of the roof is ranked as either IV or
8、V on the fragility scale. These geological conditions present support problems and there are the usual underground temperature troubles.Before 1997 gas was not satisfactorily extracted. The annual extraction rate was 5.2 million m3 and this average extraction rate was merely 3% of the gas production
9、. Therefore, gas accidents frequently occurred in the area and mine productivity remained ata low level. During the decade from 1987 to 1997 five extremely serious gas accidents occurred which caused a total of 293 deaths. In November of 1997 two extremely serious gas accidents occurred which caused
10、 133 deaths. As a consequence of this, the area became notorious for frequent gas accidents and the annual coal output during that period remained as low as 810 million tons.With the gradual development of gassy deep mine working technology the area has witnessed much safer production, a record whic
11、h gets better with each passing day.2 Simultaneous Coal-Gas Extraction TechnologiesGas troubles are mainly caused by working activities. Hence, a combination of technologies, including things like working methods, working sequences, the principles of stratum movement caused by working, the principle
12、s of gas pressure relief or methods for gas extraction, should be considered simultaneously when designing coal-gas extraction methods.2.1 Decision of pressure-relief seamIn the Huainan area there are 918 workable seams. They are numbered in reverse order to their levels as groups A, B, C, D and E a
13、nd have a total workable thickness of 2234 m. The features of the coal seams are shown in Table 1. With such a layout scientific selection of the initial working seam will be a critical decision to make.2.1.1 Intrinsic safety principleWhen beginning to mine a coal seam group, for the sake of intrins
14、ic safe mining, a seam comparatively low in gas content and burst risk should be selected as the pressure-relief seam for the following seams. For this purpose, in the Huainan area, seam 11-2 is selected as the pressure-relief seam for seam 13-1 below it; seam B8 is selected for seam B6 above it; se
15、am B10 is selected for seam B11 below it; and seam 15 is selected for seam 13 above it. These selections, and the corresponding workings, are all successful 23.The key technique of the pressure-relief seam lies in the roof bore-hole, or roadway drainage technology. The key to successful implementati
16、on of roof borehole, or roadway drainage, technology lies in the proper location of the gas concentration. Theoretical studies, numerical simulations and in-situ surveys and measurements all show that under the present seam and roof conditions in the Huainan area concentration of gas are located in circular cranny rings vertically825 m above the roof and 030 m below the air return way 46. Therefore, roof boreholes and roadway dr
