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    Longwall exp india-expectations Longwall exp india-expectations Document Transcript

    • Longwall Mining in India- Experiences and Expectations SYNOPSIS: With ever increasing demand of coal, need for implementation of bulk producing coal-mining projects has become inevitable. In the past two decades the increased demand for coal was met by opening more number of opencast mines. With the depletion of shallow reserves its high time that most modern high productive technologies are adopted in future. Mechanization in underground mines has been very slow; particularly disappointing has been the performance of high investment/high technology Long wall. It is accepted that mechanization is essential not only to reduce human drudgery in manual mining, but also for economic survival. Very low productivity and high rate of accidents due to large employment at active working zones make one wonder as to how is it that there has not been much of change in underground mines. This paper attempts to deal with longwall experiences in India and various reasons for slow progress of longwall mining and the necessity for immediate action for long term sustenance of coal mining industry. ENERGY SCENARIO World Economic growth the world over is driven by energy, whether in the form of finite resources such as coal, oil and gas or in renewable forms such as hydroelectric, wind, solar and biomass, or its converted form, electricity. Coal provides for around 23% of global primary energy needs and generating 38% of world’s electricity at present. World coal consumption is projected to go up from 4.7 billion tonnes in 1999 to 6.4 billion tonnes by 2020 primarily in China and India, which are expected to account for 75% of the increased consumption. Coal use in developing Asia alone is projected to increase by 1.8 billion tons. China and India together are projected to account for 29 percent of the total increase in energy consumption worldwide between 1999 and 2020 and 83 percent of the world’s total projected increase in coal use, on a BTU basis.
    • INDIA Coal accounts for 63% of the country's energy needs. Commercial energy consumption in India has grown from a level of about 26% to 68% in the last four & half decades. The current per capita primary energy consumption in India is about 243 kgoe/year, which is well below that of developed countries. Driven by the rising population, expanding economy and a quest for improved quality of life, energy usage in India is expected to rise to around 450 kgoe/year in 2010. Considering the limited reserve potentiality of petroleum & natural gas, eco-conservation restriction on Hydel projects and geo-political perception of nuclear power, coal will continue to occupy centre-stage of India's energy scenario. India’s installed capacity for power generation has tripled over the last 20 years and now exceeds 101,000 MW. However, the total demand is expected to increase by another 3.5 times in the next two decades, even under a best-case scenario that envisions intensified efforts to modernize power plants, improve transmission and distribution efficiency, and adopt more efficient generation technologies. The soaring demand for power will necessitate a tripling of the installed generation capacity from 101,000 to 292,000 MW over the next two decades. The projected fuel mix for power generation from various sources is shown below. At least two-thirds of this power will have to come from thermal sources—coal, oil and gas— 2
    • even under the best-case scenario (Best Case Scenario- BCS, Business As Usual- BAU). This will mean a spiraling cost for imported fuels, including coal, since even a doubling of domestic coal production would not be sufficient to meet the demand. The overall growth in demand for all forms of fuel will mirror the growth in the power sector. Even under the alternative scenario, total coal demand will nearly double, and both oil and gas demand will triple, as shown in Table 1. There does not appear any alternative to coal for meeting the energy needs of the country in the foreseeable future. Table-1 Year Coal Oil Gas (Million tonnes) (Million tonnes) (Million tonnes) 1997 311 83 21.5 2020 (BAU) 688 245 70.8 2020 BCS 538 195 64.7 Source: Planning Commission’s India Vision 2020 COAL RESERVES- TECHNOLOGICAL OPTIONS India is the third largest coal producer in the world. With hard coal reserves of around 240 billion tonnes, out of which 90 billion tonnes are proven, Indian coal offers a unique eco-friendly fuel source to domestic energy market for the next century and 3
    • beyond. In World’s hard coal production scenario1, 70 percent of coal comes from underground mining. Out of the total underground production 70% is contributed by mechanized longwall constituting about 50% of the total hard coal production. Scenario in India is just the reverse. Total annual coal production in India is about 340 million tonnes (m.t) out of which nearly 80% is from Opencast Mines. Coal India produces about 90% of total Indian coal production and SCCL’s share is about 10%. Coal production has to be increased by over 500 m.t in the next 15 years 2, Public sectors companies are expected to increase their production level by over 250 m.t by 2011-12, a gap of over 260 m.t which still remains would have to met by imports or induction of private capital. The proven technology for production and productivity all over the World is Longwall. Longwall mining in the world is moving towards increased face dimensions, least cost per tonne, higher productivity and lesser face transfer periods. The production from each face is ranging from 1 million tonnes per annum (mtpa) to 4 mtpa, though there are certain extremes of 8 mtpa. The trend for the past three decades (during post nationalized period) in India of meeting the increased demand of coal by opening more number of open cast mines cannot continue indefinitely. Especially this assumes greater significance in view of the higher (Two and a Half times) Reserves/Production ratio of underground mineable reserves when compared to opencastable reserves. Environmental degradation, problems in diverting forestland may further limit the expansion of open cast mines. The increasing trend in the consumption of coal requires the construction of new mines and expansion of existing mines. The future challenges are confined not only to increase the coal production but also to increase the coal recovery, productivity, health and safety conditions and to minimize environmental disturbances resulting from the production processes. In view of long gestation period for deep underground mines it is time that appropriate strategies for meeting demand of coal from underground mines are put into operation. For bulk production of coal from underground mining, particularly at greater depths, the proven technology world over is Long wall. To compensate the diminishing production from opencast mines, longwall faces are to be planned with minimum production capability of 1 million tonnes per annum. 4
    • For economic survival of the nation, not only the physical targets of coal production are to be fulfilled, but also is to be produced at competitive costs. In formulating an overall strategy on the means and measures of raising the quantum of production, a major consideration will be that of choice of technology. The reserves amenable to opencast mining also include reserves locked up under reserves forest, under built up area, which are difficult to evaluate under the present socio-political milieu. As the opencast mines are gradually going into adverse economic stripping ratio, higher production has to be achieved from underground mines to meet growing demand of coal4. Thickness wise coal reserves in India Coal seam thickness (m) % of share 0.5.1.5 15 1.5.3.5 15 3.5.5.0 12 5.0.10.0 20 10.0.20.0 19 Above 20 19 Longwall mining, with its accompanying advantages of higher extraction, increased safety and higher established as a mining method for coal seams of 1-5m thickness, although the initial investment for longwall mining panel is substantially higher than that for bord & pillar method. In other words this method assumes greater importance because much of high quality coal found in deeper seams can be mined out only by Longwall mining method. The tables / graphs given below present the status of longwall in India. LONGWALL PRODUCTION (LT) YEAR CIL SCCL 1983-84 1.33 1984-85 3.99 2.47 1985-86 6.48 5.75 1986-87 11.05 6.18 5
    • 1987-88 8.13 6.12 1988-89 11.82 6.12 1989-90 11.86 4.62 1990-91 14.87 6.32 1991-92 14.12 12.17 1992-93 11.08 13.2 1993-94 10.72 16.1 1994-95 18.19 10.4 1995-96 15.84 20.19 1996-97 14.52 22.9 1997-98 11.15 19.3 1998-99 17.59 16.42 1999-00 19.34 15.79 2000-01 13.66 20001-02 11.27 STATUS OF INDIAN LONGWALL MINING Sl.No. PROJECT Rated Capacity (TPD) ECL 1 Jhanjra 1&2 Inc. 1476 2 Jhanjra 1&2 Inc. 3000 3 Jhanjra-MIC 1476 BCCL 4 ML-IV 860 5 ML-V 840 6 ML-VI 470 7 ML-VII 3200 SECL 8 Balarampur 1950 9 New Kumuda 1950 10 Rajendra 2300 SCCL 11 VK-7 Inc 1600 12 JK-5 Inc 2000 13 GDK-10A Inc 2200 14 GDK-9 Inc 1900 15 PVK 2200 India was not a late starter in its approach towards this technology, but for reasons discussed in this paper, Longwall mining had limited success so far. However in view of the necessity for exploiting deeper deposits and for the aforementioned reasons (Demand-Supply, Reserves etc.,) there is no doubt that Longwall Mining will be the need of the day. Hence it is imperative to reflect on our (Indian) experiences in Longwall 6
    • mining and arrive at tangible measures to make Longwall mining in India more productive and progressive. INDIAN LONGWALL MINING- PAST EXPERIENCES In seventies, the mining community of India at large, forced by the technological developments in the competitive oil industry, was forced to make substantial progress in terms of productivity and cost reduction. During this period there were many innovative initiatives and successful projects, which gave the required boost to the mining industry. With this tempo the industry marched forward for considerable period. It will not be out of place to mention that the during those eventful years there was overall development in all mining technologies irrespective of their contribution to the overall quantity of production. Further, sufficient thought, innovation and development took place in all direction. The longwall technology was also give the required attention along with others and ambitious projects were envisaged. Unfortunately, this tempo could not be continued as a result of exploration shallower deposits. The introduction of first mechanized powered support longwall caving face in August 1978 at Moonidih marked a major step forward in the introduction of advanced technology mining system in India coal Industry. In between 1978 to 1985, a number of first generation mechanized longwall packages were introduced in Moonidih colliery (total 3 longwall packages, first one installed in August 1978, second one in July 1980 and third one in October 1985 of Jhanjra Coal field, Seetalpur colliery (One longwall package installed in October 1982) and Dhemomain colliery (one longwall package installed in November 1982) of Raniganj Coalfield, Pathakhera colliery (One longwall package installed in September 1982) of Satpura coal basin and GDK-7/VK-7 mines of Singareni Collieries Company Limited (One longwall package in each mine, first one installed in September 1983 and the second one installed in June 1985) of Pranahita Godavari Valley Coal field. In SCCL, Longwall technology was introduced at GDK-7 Incline in 1983 and after successful completion of two faces equipment was shifted to GDK-9 Incline where the Longwall face collapsed due to inadequacy of support capacity. In GDK-11A initially 7
    • 3 longwall faces have planned with 450T capacity supports, which also failed due to underrating of supports. Later in GDK-10A Incline Longwall method is introduced with increased capacity of powered supports (from 450 to 800T) where it worked successfully by producing 3.5MT of coal. First time in PVK, 2-Chinese Longwall sets are introduced to work the Top seam coal, performance of these sets are good to some extent, but effected by lot of breakdowns of Shearer and other connected machinery with poor metallurgy. In VK-7 Incline first Longwall face was introduced in 1984 with 360T capacity, in due course of time the face length is reduced to 90m 150m to suit the underrated capacity of supports. JK-5 Incline Longwall experiences are also in the similar lines with further successful experiments in working under caved goaf and working in inclined seams (1 in 3). The faces at SCCL in GDK-7 and VK-7 did well in comparison with the other faces, which experienced caving difficulties. The supports, which were underrated, got damaged. Among various designs of longwall cutter loader, the Anderson-Shearer type has been found to be the most successful. In early nineties, higher capacity longwall powered supports were provided for the faces at Churcha (seam V) in SECL, Jhanjra (RVII seam) in ECL, JK-5 (Queen seam), GDK-11A 3sets (seam-1), GDK-10A (seam-1) and PVK (Queen seam)-2sets. Churcha longwall face, which was worked with 680T supports, yielded promising results initially but collapsed at a distance of 189m from barrier due mainly to dynamic weighting. The Jhanjra project represents a totally unique situation. The depth of mining was less than 50m in most of the panels with thickness of hard cover as low as 16m at some locales. This project, which was started in collaboration with USSR, ran into acute spares problem due to turmoil in USSR. Later determined efforts by our people made the development of indigenous spares possible. Longwall faces at Kottadih worked well with single lift extraction of 4.5m but third panel of Kottadih collapsed due to dynamic weighting and underrated supports causing three fatalities. The longwall powered supports from Dhemomain and Churcha projects were shifted to Jhanjra. 8
    • The unfavorable Geo-mining condition has been the main hindrance in the success of longwall technology. This is evident from the fact that a number of longwall faces, which were planned for the working longwall, have been withdrawn. Moonidih project, Pooteki-balihari project, Balgoth project of BCCL had to be changed from Longwall and similarly longwall planned in Kaju area of CCL had to abandoned due to presence of dykes/faults etc. Barring the collapses, first at Churcha and then at Kottadih, the faces at Jhanjra, GDK-10A, JK-5 and VK-7 mines in SCCL gave consistently good results. LONGWALL TECHNOLOGY IN INDIA - THE PRESENT AND THE FUTURE For depths beyond 300m, Long wall is likely to be the main method for bulk production, and probably continuous miners will be used wherever conditions permit. Unfortunately no serious efforts has been made in respect of R&D for liquidating standing pillars which account for huge locked up reserves to the tune of about 3000 million tonnes. Maintaining these workings itself involves high cost in addition to losses due to deterioration, fires and safety problems. Present method of extraction of these reserves particularly in multi-seam workings by stowing is a slow process and the availability of sand is not assured in many coal-mining areas. There is an urgent need for planning liquidation of these reserves by mechanized methods. It is possible to use Longwall at many such places but the same needs determined effort and major policy decisions. There is a need to look objectively in order to avoid earlier mistakes from recurring. With the likely reduction of contribution from Open cast and the more or less stagnant production from Underground mining by Conventional methods, it is time that an impetus is given to boost Long wall Technology to able to meet the future energy needs of the country. Though the first fully mechanized Long wall face was commissioned in India in 1978 in Moonidih Colliery and more long wall sets came up in CIL and SCCL, Long wall mining has not really taken off in India, barring a few exceptions of moderately successful faces (in range of 2500 to 3000 t/day). Even the one’s which have comparatively performed better have not proved economically viable beyond 9
    • second/third year of operation due to variety of reasons. In retrospect it appears that the Longwall technology in India has neither been accepted nor rejected. In all the forums and discussions at various levels it is accepted that longwall technology needs to be pushed forward vigorously. There is a consensus also that time is running out and unless immediate steps are taken coal industry may be facing a serious problem because the gestation period in underground projects is quite long. Something more than seminars, discussions, forming committees needs to be done. In the present public sector scenario longwall is difficult to work economically as is the case with most of the underground mining, yet there is no alternative to longwall on long term, if coal is to be produced from underground. On the positive side, coal companies have now gained sufficient experiences right from senior executive level to front line workforce to be able to plan, execute and work longwall faces. What are required are policy decisions and logistics. It is obvious that with the high cost of imported equipment and irregular supply of critical spares, without large blocks of coal identified for longwall, hesitation to make investment in view of its limited economic success has resulted in slow pace of longwall. The reasons for failure are not due to any deficiency in the technology but due to comparison of the economics with the opencast providing short-term cheap alternative. Yet the fact remains that beyond 300mts depth, Longwall method of mining will remain predominant method of work and it is better that solutions are sought now. LONGWALL IN SCCL- FUTURE 1. 14 Coal Mining Blocks have been identified in SCCL and the project reports in respect of Seven Projects are in various stages. 2. A beginning is made in regard to Shaft sinking in GDK-10A property for reaching deeper deposits of GDK-10A and the same will be replicated for Vakilpalli block also. Further, the Bhoopalpalli coalfields (KTK-7 & KTK-8 Blocks) of SCCL are steeply inclined where it is proposed to introduce Longwall technology. In view of the limited in house expertise in working inclined seams with longwall mechanization, consultants are being contacted for developing effective method of mining. LONGWALL TECHNOLOGY- REASONS FOR SLOW PROGRESS 10
    •  Large expansion in open cast mining in the past two decades provided cheaper and safe method for bulk coal production and as a result long wall had to take back seat.  Clear strategies were not pursued for its sustenance as there was mixed results from long wall in the early years of its introduction.  Longwalls were introduced mostly in the blocks left over by working bord and pillar method. Clean and extensive blocks have not been identified. Even the smaller blocks, which were identified, were of inferior grade coal.  Longwall had to co exist with the conventional mining in most of the mines, which caused management problems.  There were some deficiencies in the spares management. Most of the spares had to be imported and the supplies were not reaching in time.  Coal companies were sensitive to the failures of a few long wall faces and were not prepared to risk huge investments.  Development could not keep pace with the extraction of Long wall panels, slow progress in dip has delayed the formation of Long wall panels and affected the performance. In spite of Long wall not having achieved any great success yet the cost of production in Long wall taken alone, safety and productivity are in favour of Long wall than any other underground method5. The accident statistics reveal that the fatality rate for million tonnes of coal produced by Longwall is very near to that of opencast. RECOMMENDATIONS a. Long wall should be promoted as a technology mission. b. A high level thrust group could be constituted at national level with the following objectives:  To render expertise in long wall  To promote research and professional excellence with technological forecasting  To interact with national and international organizations working in the field for the promotion of the Long wall technology in Indian coal industry  To coordinate the activities of various companies connected to Longwall in the country to avoid duplication  To identify and plan the training needs of long wall technology in the country. 11
    • c. Huge investments are required for extraction of coal from depth (more than 300m). Detailed exploration, sinking of shafts, development of infrastructure for introduction of Long wall technology requires advance planning as the gestation periods are long. But all these have to be treated as an investment for future. It is suggested that special funds are generated by a cess on current OC production or from other sources. This could be utilized for development of Long wall blocks beyond 300m including shaft sinking, tunnel drivage, trunk roads and exploration etc., a separate company or department could be formed to undertake exclusively Long wall/ infrastructure development activities. Theses blocks may be planned to last for 10 years and could be given to coal companies on the risk/gain share basis, for high performance long wall faces. Only then it could be expected that the long walls perform to the international standards. d. R&D efforts are required for extraction of standing pillars, which approximate to about 3000 million tonnes up to a depth of 300m. Approximately one third of the standing pillars could be liquidated by application of modified Long wall system, which could also open up large vistas for introduction of Long wall. This could in turn give a fillip for the development of indigenous long wall equipment. It would economic working of long wall in the country. e. Concerted efforts are required by the policy makers, Coal companies and manufacturers to translate the ideas into concrete action and reap the benefits of technology in the years to come. CONCLUSION 1. Decision-making by persons not conversant with Longwall is one of the factors for poor performance of Longwall. 2. Improper Maintenance, indegenisation of Spares with inadequate expertise are major reasons for the Indian Longwall failure 3. Adequate Support Calculations and implementation of Rapid face advance are essential for the LW success. 4. Though Longwall expertise is there/they are not properly strengthened. Hence the work done in past 20 years for indegenisation, which is the middle level of learning curve, is not properly utilized. If proper strategies are adopted there is a definite chance to climb the learning curve. 5. Foreign participation is required for extraction of thin seams and steeply inclined seams. This may be adopted as a joint venture participation with country having such expertise. 6. The manufacturing companies of India such as MAMC and Jessop are to be reconstructed/ re-organized (with private company participation) to develop quality indigenous longwall equipment with the collaboration of foreign 12
    • manufacturing companies and even manufacturing of the equipment by the foreign companies in India. This is possible only when sufficient numbers of longwall blocks are identified and sufficient market is assured. 7. There is the capability to plan and execute longwall projects provided Govt. or coal companies are prepared to make investments. There is also a need to have a body at National level for policy guidance, R&D development, awareness and monitoring to ensure implementation of long term strategies in respect of bulk coal production from longwall on the lines of technology missions functioning in respect of other important areas like C.DOT, Irrigation (Central Board of Irrigation and Power) etc. 8. Concerted efforts are required by the policy makers, Coal companies and manufacturers to translate the ideas into concrete action and reap the benefits of Longwall Technology in the years to come. ACKNOWLEDGEMENT The views expressed are those of the authors and should not be attributed to Singareni Collieries. Nor do any of the conclusions represent the official policy of Singareni Collieries or it’s Directors or the country they represent. REFERENCES 1. SN. Mukherjee., IM&EJ, Feb 2000, a Technical paper on “Future of underground mine mechanization in India”. 2. Anwar Ahmed, EE (E&M), CMTM, March 2003, a Technical paper on “Challenges before coal industry & strategies ahead (Balrampur Longwall Experience)”. 3. Mukunda Reddy, CGM, SCCL., Indo-polish working group, a Technical paper on “Technological options for future coal mining – A review”. 4. “Compendium on Experiences of Longwall Technology”, SCCL, June 2002. 5. CL.Hanjura, D.Suresh, L.Sudhakar, SCCL, MMF, December 2002., a Technical paper on “Longwall technology – the need for promotion”. 6. Information Bulletin published by the Ministry of Coal, India 13