張小樓煤礦0.9Mta新井設(shè)計含5張CAD圖.zip,張小樓,煤礦,0.9,Mta,設(shè)計,CAD 英文原文 Gas content based outburst control technology in Australia Sheng Xue CSIRO Exploration & Mining, PO Box 883, Kenmore, Queensland 4069 Australia Tel.: +61 7 3327 4443; Fax: +61 7 3327 4666; Email: sheng.xue@csiro.au Abstract The violent and unexpected nature of the phenomena enhances the mining risk and danger to mine workers. A number of techniques are used to predict and prevent the occurrence of the outbursts and to protect mine workers from the consequence of outburst incidents. This paper outlines the gas content based outburst control technology, one of the successful outburst control technologies, applied in Australian coal mines. Some aspects of the current technology, which are perceived as either inadequate, inappropriate or impractical, are also highlighted in this paper together with the research strategies to address the concerns. Keywords: Coal Mining; Outburst; Outburst prediction and control; Gas content 1 Introduction An outburst of coal and gas is the sudden release of a large quantity of gas in conjunction with the ejection of coal and associated rock, into the working face or mine workings. Outbursts are hazardous through the mechanical effects of particle ejection and by asphyxiation and possible explosion from the gas produced. Outbursts occur as a result of mutual interaction of a number of factors such as rock pressure, gas present in coal, and physical and mechanical properties of coal. Gas content is an important factor in outburst proneness. Unless gas content reaches a critical level, outbursts of gas and coal will not manifest themselves at all. Though gas content, as a basic coal seam parameter, has been used to develop many gas-related indices for outburst prediction in Australia, this has not been used in practice elsewhere. This may be due to different coal seam conditions outside Australia and the lack of the development of a rapid method to measure gas content. Outbursts were a common occurrence in gassy Australian mines, up until the industry adopted outburst threshold gas content limits following a fatality at West Cliff Colliery in 1994. Since that time, only a handful of outbursts have been occurred with no fatalities. The Australian coal industry has achieved these results mainly through intensive gas pre-drainage practices as well as the use of shot firing or remote mining in coal that is difficult to drain. The current threshold gas contents have been successful in preventing outbursts in Australia. However, there are a number of aspects of the current gas content based control technologies of managing outburst risk that are perceived as either inadequate, inappropriate or impractical/costly in some seam conditions. Technology roadmaps are developed to address the issues. 2 Outburst Control Protocols 2.1 Development history in Australia Outbursts of gas and coal have occurred in both the major coal producing basins of Australia, namely the southern part of the Sydney basin (Illawarra coal field) and the central and northern part of the Bowen basin. Both pure methane and pure carbon dioxide outbursts have occurred in Australian coal mines. Over 700 outbursts have occurred in Australian mines over the last 100 years. The first outburst occurred in 1895 in Metropolitan Colliery in the Bulli seam. Since then 465 outbursts have occurred in the Bulli seam. The latest fatality from an outburst occurred in Australia in 1994. It is, therefore, not surprising that the outburst control technologies in Australia were developed to manage outburst risks in the Bulli seam. The occurrence of outbursts in the Bulli seam was thoroughly studied by a number of researchers in the early 1980s (Hargraves, 1985; Lama, 1982). The studies revealed that the outbursts in the Bulli seam were characterised by the following: · Depth of workings is 350 – 600 m, dip of the seam varies from 20 to 50, gas content varies with seam depth (from 3-6 m3/t at 350m depth to 15-20 m3/t at 600m depth), seam gas composition varies from pure methane to carbon dioxide, strength of coal ranges from 8 – 21 MPa, ratio of two horizontal stresses varies from 1.6 to 2.4, intermediate principal stress is 1 – 1.6 times the vertical stress; · Outbursts often occurred in development headings; · As long as minimum distance (about 2.5m) from the structures (faults, dyke, strike slip, sheared zones etc) is maintained, an outburst will not occur; when the barrier width of solid coal and the rib line of a heading was reduced to under 2.5m, an outburst precipitated; · No signs of any failure due to induced stress in coal in areas of outbursts; and Majority of outbursts have occurred on structures. Based upon these studies, a mechanism of outbursts in the Bulli seam was postulated. Figure 1 shows the generalised concept. The phenomenon of outburst occurrence in the Bulli seam was placed in the third quadrant (high gas, low stress/strength ratio). As the face approaches the structures and the minimum distance (thickness of barrier) is breached, the higher gas pressure displaces the material from the face and high flow rate provides the energy that resulted in the initiation of an outburst. Figure 1. Effect of stress and gas on stability of excavations (after Lama, 1995) The strength of the Bulli seam is placed somewhere in the middle of the band of coal strength around the world. The stress levels occurring in the seam are medium and since there is no indication of the role of stress, it was concluded that mining induced stress does not play an important role in the outbursts in the Bulli seam. Ejection of coal in outbursts in the Bulli seam is all gas controlled. It was thus concluded that virtually all outbursts in the Bulli seam are gas controlled and associated with structures, mostly shear zones, dykes and faults and the safe zone varies from 1 m to 2.5 m. Certain indices based upon measurement of gas emission rate were developed to predict outburst conditions in the Bulli seam in Australia (Hargraves, 1963; Hargraves et al, 1964; Lunarzewski, 1995). However several problems existed with the determination of the indices. These include effect of moisture, variability of coal ply, location (face or corner), depth of hole, etc. With the introduction of high performance machines and particularly longwall mining, these prediction methods which require frequent measurements in hole depth of 2-3 m, was found to be unsuitable and fell into disrepute as they greatly impinged upon productivity and were at the same time unreliable. Based upon these studies and comparison with overseas data, threshold values for the safe mining of the Bulli seam were proposed in 1991 (Lama, 1991 & 1995). These threshold values took into consideration the differences in the initial desorption rate of methane and carbon dioxide as well as the effect of carbon dioxide on the strength of coal. These values were conservative and were proposed to take into account high rates of development of headings. Since 1991 these threshold values were further modified after more gas content data in the Bulli seam was collected and analysed. 2.2 Threshold gas content On 4 May 1994, after reviewing the findings of the investigation relating to the fatal accident at West Cliff Colliery on 25 January 1994, the results of examination of operational outburst management, and other related event, the then New South Wales Chief Inspector of Mines applied a Section 63 notice of Coal Mines Regulation Act 1982 to the New South Wales coal industry, setting outburst threshold gas content limits for mining in the Bulli seam. The threshold value of gas content was based on studies of the outburst occurrences in the Bulli seam, comparison with overseas data, differences in the initial desorption rate of methane and carbon dioxide, effect of gas on the strength of coal, and a considerable safety margin. Part of the Notice is quoted as follows: (a) In situ total gas content and composition of the Bulli Seam coal, in accordance with AS3980 or an equivalent standard, shall be routinely conducted in the Bulli Seam as part of development roadway operations. The mine manager shall ensure that sufficient samples are taken at appropriate locations in advance of development roadways to determine seam gas content and composition of the coal to be mined at all time. (b) The mine manager shall take all reasonably practical steps to identify structures ahead of all development roadways in the Bulli Seam. If, in the opinion of the mine manager, a structure that has potential to generate an outburst, is identified or inferred from geological or other available information, or observed during the course of the mining, the mining in the vicinity of the structure shall be carried out under Outburst Mining Procedures. (c) Normal mining shall only be conducted where: 1. No structure has been identified as in (b), and 2. Total gas contents in (a) are less than 9 m3/tonne for CH4 or 5 m3/tonne for CO2, or for a mixture of these two gases, a gas content in the proportion of the percentages of each gas between these two limits. (d) Development roadways may be formed where the total gas content is higher than that set out above but only under full outburst procedures or fully remote mining. (e) Development roadways shall not be formed, except by fully remote operation methods, where the total gas contents in (a) are greater than 12 m3/tonne for CH4 or 8 m3/tonne for CO2 or for a mixture of these two gases, gas content in the proportion of percentages of each gas between these two limits The Section 63 notice declared that the occurrence of outbursts was not acceptable except under remote mining conditions and the threshold gas contents were based on the worst case scenario. Although the Section 63 notice was imposed on the coal mines in New South Wales, setting the Bulli seam threshold limits for mining, operators of gassy mines outside of the Bulli seam, including Queensland producers, have successfully applied the Bulli seam protocols with some modifications. Since the threshold gas contents were set and implemented in 1994, only nine small outbursts have been recorded in the Australian coal industry. None of these outbursts resulted in a fatality. Furthermore, outbursts have not occurred during the period in Australia when mining has been conducted in coal which was drained to below the threshold values. 2.3 Outburst Management Outburst management relates to managing the outburst risk. This risk management approach utilizes outburst prediction and prevention techniques and protection measures. The inter-relationship of outburst prediction, prevention and protection is explained diagrammatically in Figure 2. It involves procedures and processes aimed at eliminating the occurrence of outbursts. Figure 2. Diagrammatic representation of outburst management (after Harvey, 2002) It should be noted that there is no one specific technology or mining technique, which could be used to guarantee safety in outburst prone mines. The effective management of the outburst risk involves a number of techniques and technologies. These technologies including measurement of seam gas content and composition, identification of geological structures, use of gas drainage techniques, identifying in situ and mining-induced stress regimes should be integrated in outburst management plans. It is through the application of outburst management plans that outburst risk is controlled. While it is of primary importance that any OMP is developed for each specific site with due regard for geological and mining conditions, for the plan to be considered to be acceptable it must have a number of key elements. These elements are contained within guidance documentation as provided by the Department of Mineral Resources (MDG 1004, 1995). An OMP comprises general requirements, plan elements and processes. While the general requirements provide a basis for the development and implementation of OMPs and the plan elements provide the broad management framework, the processes are those activities and equipment than form the day to day operation of an OMP and which are to be performed under controlled conditions. The human and organisational aspects of an OMP are considered as equal in importance to the technologies utilized. 3 Issues and Research Roadmap The current approach of outburst management, the OMP in combination with threshold gas content limits, has greatly reduced the number of outburst incidents in Australia since its implementation in 1995. However, there are a number of aspects of the current system of managing outburst risk that are perceived as either inadequate or inappropriate or impractical in some seam conditions. These issues include mainly: · The one-parameter approach of gas content is simplistic in ignoring other factors which might increase or decrease outburst propensity; it may be inadequate; · The methodology for determining safe threshold gas contents was based on a limited local dataset; the proposed threshold values were conservative at the time; and their application to other seams and locations might be inappropriate; and The implementation of the current approach in areas of poor drainability and drillability is impractical. To address the issues mentioned above and to ensure safe and reliable mining using timely and cost effective outburst controls (strategic goals), an Outburst Research Task Group (AORT) comprising representatives from coal producers, researchers, consultants and other stakeholders was formed in 2005 to steer further outburst R&D. The strategic goals are achieved through the development of a technology roadmap. The roadmap has three key elements: defining goals, current status and pathways. Four outburst research goals were developed by AORT in 2006. They are: 1. Review and identification of the outburst mechanism and the roles of the various parameters, and the parameters must be practically measurable; 2. Understanding of the (structural) conditions which cause zones of poor drainability or drillability and therefore, increase outburst proneness, and to confidently locate these zones with adequate response time; 3. Development and application of tools (methods) to rapidly, efficiently, and preferably economically reduce gas content/pressure as a routine and as a last resort, plus awareness; 4. Facilitation of continuous improvement in outburst management through information transfer, development of more efficient procedures and upgrading of management plans. Current status of outburst controls has been extensively reviewed and compiled by Hanes (2004). Based on the recommendations of Hanes’ work and on subsequent deliberations by AORT, an outburst research roadmap has been developed by AORT in 2006. The roadmap has been structured under the generic hazard management headings of prediction, prevention and protection. Key elements are outlined under each heading and current status of each element is described with “next step” research recommendations proposed in relation to current status assessment. The key elements in prediction of outburst conditions include characterisation of outburst parameters, locating structures, modelling outbursts, and monitoring for outburst conditions; the key elements in prevention of outbursts include reducing gas content and pressure and enhancing permeability; the key elements in protection against harms from outbursts include education and training, protocols and standards, sustainable use of explosives and remote mining. Five research themes have been developed by AORT in 2007 to move the roadmap research projects towards a plan. Each theme addresses a number of research elements included in the outburst research roadmap. The themes are: 1. Collect and interpret key outburst parameters efficiently; 2. Refine methods to locate and characterise structural features that increase outburst proneness; 3. Improve efficiency and effectiveness of drainage systems; 4. Education, training and communication of outburst management; and 5. Challenge and improve current outburst protocols. At present there are a dozen active outburst research projects in Australia. The projects are related to improving drilling technology, gas drainage, outburst risk assessment, and understanding of outburst mechanism. 4 Conclusions Outburst risk controls in Australia utilize management plans and threshold gas content values. An outburst management plan is based on the assessment of the outburst risk to be managed at the particular mine and threshold gas content values are based upon the values set for Bulli seam with some modifications. Current approach of outburst controls has been successful in preventing outbursts in Australia. However, there are a number of aspects of the current gas content based control technologies of managing outburst risk that are perceived as either inadequate or impractical in some seam conditions. Technology roadmaps have been developed to address the issues and a cluster of research themes relating to the key elements of the roadmap have been developed. References [1]Hanes, J, 2004, Outburst scoping study, Australian Coal Association Research Program Report C10012, Australia. [2]Hargraves, AJ, 1963, Instantaneous outbursts of coal and gas, thesis submitted to the University of Sydney for the degree of PhD, Australia. [3]Hargraves, AJ, Hindmarsh, J and McCoy, A, 1964, The control of instantaneous outbursts at Metropolitan Colliery, NSW, In: Proceedings of Australasian Institute of Mining and Metallurgy, no. 209, pp. 38-66. [4]Hargraves, AJ, 1985, Instantaneous outbursts of coal and gas, In: Proceedings of Australasian Institute of Mining and Metallurgy, vol. 186, no. 6, pp. 21-72. [5]Harvey, C, 2002, History of outbursts in Australia and current management controls, In: Proceedings of 2002 Coal Operators’ Conference, 6-8 February 2002, Wollongong, Australia, pp. 36-42. [6]Lama, RD, 1982, Outbursts and gas drainage investigations, End of Grant Report, NERDDP Project No. 578, Department of Primary Industries, Canberra, Australia. [7]Lama, RD, 1991, Control of outbursts in the Bulli seam, Kembla Coal & Coke Internal Report, December, 1991. [8]Lama, RD, 1995, Saf gas content threshold value for safety against outbursts in the mining of the Bulli seam, In: Proceedings of International Symposium-cum-Workshop on Management and Control of High Gas Emissions and Outbursts in Underground Coal Mines, Wollongong, 20-24 March, pp. 175-189. [9]Lama, RD and Bodziony, J, 1996, Outbursts of Gas, Coal and Rock in Underground Coal Mines, R D Lama and Associates, Wollongong, Australia. [10]Lunarzewski, L, 1995, Immediate assessment of in-situ gas content using underground manometric desorbometer readings, In: Proceedings of International Symposium-cum-Workshop on Management and Control of High Gas Emissions and Outbursts in Underground Coal Mines, Wollongong, 20-24 March, pp. 569-571. [11]MDG1004, 1995, Outburst mining guidelines, Department of Mineral Resources, New South Wales, Australia.  中文譯文 瓦斯的突出控制技術(shù)在澳大利亞的應(yīng)用 Sheng Xue CSIRO Exploration & Mining, PO Box 883, Kenmore, Queensland 4069 Australia 摘要：爆炸和難以預(yù)料的自然現(xiàn)象增加了煤礦工人開采過程中的危險。大量的技術(shù)被用來預(yù)測和防止發(fā)生爆炸，并保護礦工預(yù)防從突發(fā)事件。本文主要介紹了瓦斯的突出控制技術(shù),這是眾多成功的突出控制技術(shù)的一個,廣泛應(yīng)用于澳大利亞煤礦。目前這種技術(shù)在某些方面,被視為既不充足,不恰當(dāng)或不切實際,本文中的研究策略就是來解決這些問題的。 關(guān)鍵詞:煤礦；突出；突出預(yù)測和控制；瓦斯含量 1、簡介 煤與瓦斯突出是從煤巖壁內(nèi)突然釋放的大量的氣體并向工作面或者工作地點噴發(fā)大量煤炭和巖石。突出是通過力學(xué)效應(yīng)的粒子彈射和通過爆炸產(chǎn)生的氣體使人窒息而產(chǎn)生危險。突出會導(dǎo)致相互交互的許多因素如巖石的壓力、煤炭中的氣體和煤的物理力學(xué)特性。 瓦斯含量是瓦斯突出的一個重要的因素。除非瓦斯含量達到一定的標(biāo)準，突出的煤與瓦斯將不會出現(xiàn)。作為煤層的一個基本參數(shù)，瓦斯含量已經(jīng)在澳大利亞被用于開發(fā)多個和天然氣有關(guān)指數(shù)對突出預(yù)測，但是這還沒有用于其他地方。這可能是由于在澳大利亞不同煤層條件下，還缺乏一種快速的方法來測量瓦斯的含量。 瓦斯含量高的澳大利亞是一個瓦斯突出頻繁的地方。直到1994年工業(yè)采用突出閾值后，瓦斯突出造成的死亡率才被西崖煤礦控制住。從那時起，只有少數(shù)的瓦斯爆炸發(fā)生,并且沒有人員傷亡。澳大利亞煤炭行業(yè)已經(jīng)通過密集的氣體pre-drainage實踐的運用以及照片的射擊或者遠程煤礦技術(shù)來取得這些結(jié)果，這些結(jié)果很難流失。在澳大利亞，標(biāo)準的瓦斯含量已成功地防止瓦斯爆炸。然而，就目前來說，天然氣含量的控制爆炸技術(shù)的風(fēng)險管理在很多方面被視為不充足、不恰當(dāng)，在不同煤層條件者也是不切實際或者昂貴的。技術(shù)路線圖正致力于解決這方面的問題。 2、