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英文原文
Why Longwall in India has not Succeeded as in other Developing Country Like China
Prof A K Ghose
Abstract Of the global hard coal production of some 3300 million tonnes during 2000-2001, China headed the league table with a production of 970 million tonnes, and with a production level of 320 million tonnes India ranked third. Both of these developing nations have large resource endowment in bituminous coal, the proved recoverable reserves at end 1999 stood at 114500 million tonnes in China and at 84396 million tonnes in India according to Survey of Energy Resources 2001 of the World Energy Council1. Coal occupies the centre-stage in the energy economy of both the nations, coal has a share of 75% of the consumption of primary energy in China while in India the share of coal is around 64% in the current mix of commercial energy2. However, any comparison between the technology levels of the two giant nations in coal production would perhaps be invidious, dictated as these are by a whole host of imponderables including the site-specific conditions of the resource endowment, differing thrusts of national policy and the socio-cultural and political milieu. Underground coal mining has a predominant share of some 94% of Chinese coal production, while in India the share is only 21%. To examine and analyze the palpable reasons for not so successful application of Longwall technology in India vis-a-vis China, one needs to examine the chronological evolution of the technology in the two nations, appraise the technogenesis of Longwall technology in both the countries and then home in on the contributory factors. This paper attempts a foray in unravelling the reasons fully cognizant of the fact that any post hoc analysis, as of date, can only outline a hypothesis of the multitude of reasons behind the apparent failure of Longwall technology in India due to subjective interpretation and perception of the issues involved. It is also not always possible to reflect by hindsight on the compulsions of the planner/decision-maker in choosing a specific strategy at any given point of time. Be that as it may, we examine here on a broad canvass the remarkable saga of growth in Longwall technology in China and the apparent under-performance of Longwall in India.
Keywords Longwall, Geotechnology, Moonidih colliery, Coal seams
LONGWALL TECHNOLOGY — GENESIS AND EVOLUTION
The seventeenth century innovation of ‘Longwall’ system in Shropshire in England has made giant strides over the past three centuries to emerge as the predominant bulk production system in global coal industry today with a share of nearly 70% of the aggregate production and is recognized as the safest, the most productive and cost effective method as well for extraction of coal seams by underground mining3. Longwall mining made its debut in Indian coal mining scene reportedly around Figure 1 Longwall tons (st) per 8-h machine shift (annual average for a single mine) since 1984
1870s; despite such head start however the progression of the technique in Indian coal industry milieu has been extremely slow and halting. From the early application to stowing faces, caved Longwalling was attempted only around early 1960s and the first mechanized powered support face, the new-age Longwall, was launched in August 1978 at Moonidih Colliery. While this marked the beginning of a major initiative in transfer of innovative Longwall technology in the relatively low technology milieu of Indian coal industry, the overall performance has fallen short of expectations and despite experiences in deploying some 33 mechanized powered support packages to date in Coal India and Singareni Collieries Company, Longwall technology in India remains a laggard, straggling miles behind the global best practices. One could cite the case of Console Energy which operated 14 Longwall mining systems of the 59 operating Longwalls in the United States in 2000, where the best Longwall’s annual production average is close to 8100 clean tonnes per 8-h machine shift. Figure 1 shows the evolution of Longwall tons (short tons) per 8-h machine shift (annual average for single console mine) since 19845. There are examples galore of such high performance faces in the United States, Australia and even in China.
In benchmarking the performance of Indian Longwall faces with those of China, it is necessary to examine the evolution of coal mining technology in India and China to provide a backdrop. India gained Independence in 1947 and commenced on the national economic planning journey in 1951. China as a nation-state came into existence in 1949 when its coal output was 32.43 million tonnes, very close to India’s coal output.
While both the nations started almost at the same base level, China’s coal odyssey has been marked by a quantum jump in production level which touched an all-time high of 1.3 billion tonnes in 1997 encompassing the three elements of the coal industry, the state-controlled mines, local mines and collective ownership and small mines. Since then, a massive restructuring of Chinese coal industry with closure of over 40 000 small coal mines has curtailed the production level to just around 970 million tonnes in 2000-2001. It is also important to highlight a major difference between Indian and Chinese Longwall experiences. Longwall mining, using the first generation mechanization systems comprising friction/hydraulic props, AFC, and shearer, kicked off almost contemporaneously around 1962-63 both in China and India. Since then, China’s leap forward in Longwall has been phenomenal and while India has been toying with a handful of powered support Longwall faces with a production of 4.52 million tonnes from 14 faces during 2000-2001, in state-controlled mines in China in 1997 there were 238 fully mechanized faces with an average annual output of 784,000 tonnes. During 1997, more than 76 fully mechanized Longwall systems produced over 1 million tonnes, of which 12 faces produced over 2 million tonnes annually. During 1999, one team in Dongtan mine of Yangzhou Coal Mining Group, Shandong Province produced 5.12 million tonnes with an OMS of 246.96 tonnes6. Benchmarking Indian Longwall faces with those of China in effect is a comparison between unequals! Between 1978 and 1985, about 200 sets of Longwall face equipment were imported in China; such acquisition of technology not only had a direct impact on increased production, but also led to direct replication of imported equipment and the domestic manufacturing capacity was significantly upgraded7. In 1980, some 75% of fully mechanized Longwall equipment were imported in China; by 1995, with absorption of new techno-logy and sheer copying of imported equipment, the share of imported equipment fell to 13.8%6. Through sustained R&D efforts over the past three decades, China has made a major breakthrough in Longwall technology for thick seams using sub-level caving (soutirage) and has emerged as the world leader in this area with record production levels and manufacture of equipment packages for sub-level caving. In 1996, there were 86 fully mechanized sub-level working faces with an aggregate output of 67 million tonnes.
Even if China lags behind the performance of the super heavyduty Longwalls in the United States or Australia, the policy thrust of the coal sector in China, the massive investment in imported and indigenous faces, the focus on ‘walking on two legs’, fast decision-making and above all the work culture in a mandarindominated society made it possible for China to launch the Longwall odyssey purposefully and achieve a quantum jump in production levels in Longwall, backed by a highly developed manufacturing base for mining equipment8. The critical success factors that were obtainable in China were simply missing in the Indian coal industry context. It is in this backdrop that one needs to appraise the ‘less than adequate performance’, an euphemism for poor performance, of Longwall technology in India.
APPRAISING THE SCORECARD FOR LONGWALL TECHNOLOGY IN INDIA
The under-performance of Longwall technology, especially of the high-investment powered support Longwall face, which made its debut in August 1978 at Moonidih Colliery, has led to much soul- searching, introspection and articulation of concern over the past 25 years in India. The collapse of heavy-duty Longwall installations at Churcha West (1989) and Kottadih (1997) has merited the attention of the Government and a number of Committees have been appointed over the years to examine the entire gamut of problems of Longwall technology and to suggest remedial measures for bringing about performance improvement. These include the H B Ghosh Committee (1983-84), the Strategic Action Group under the Chairmanship of Shri K A Sinha (1988-89), the S K Chowdhury Committee (1990) to enquire into the circumstances leading to the collapse of Churcha West Face and finally the Mahendru Committee (1998) which, besides enquiring into the collapse of Kottadih face was also charged with the responsibility of studying the performance of all past and operating Longwall faces in the country to assess and recommend the applicability of Longwall technology under Indian geo-mining conditions.
By and large, the contributory factors that have been identified for the not so successful operation of Longwall systems converge on the following:
Inadequacy of geological and geotechnical assessment of Longwall locales
n Flawed equipment selection with inadequate rating of supports, shearers and coal clearance systems
n Management failure in planning, operation, provision of service back-up and spares availability
n Failure in inculcating a culture for mechanized Longwall and creating a cadre of Longwall personnel who could serve as change agents in implementing the technology
n Issues of power supply, materials supply, ventilation, dust control and availability of clean water for hydraulic emulsions
n Absence of a viable manufacturing capacity for Longwall equipment.
All these factors culminated in either poor performance or led to collapse of faces which eroded the confidence of the industry on Longwall technology. In a number of papers, the author has undertaken critical studies on Longwall under-performance in Indian coal industry, analysed the problem dimension and pinpointed the major factors which have beleaguered Longwall technology in India8 - 11. The factors which conjointly have blighted Longwall technology can now be examined in depth under three main headings:
a) Geological and geotechnical site factors
b) Flawed planning
c) Management lacuna.
Geological and Geotechnical Site factors
Analysis of Longwall performance in 28 Longwall faces underscores the fact that investment in pre-mining geological and geotechnical investigations could have averted some of the face collapses or even reduced the risk of operations besides contributing to more careful selection of appropriate face equipment. Accurate and reliable delineation of the geology of a panel is sine qua non for establishing face and panel length avoiding any ‘geological surprises’. There are examples galore of disruptions to Longwall operations in practically every Longwall face. A few aberrant experiences include:
a. Faces at Moonidih encountered a series of step faults at the face and stringers of small dykes, the existence of which were not known at the time of face development.
b. The face at Seetalpur encountered an igneous intrusion at mid-height of the coal seam and also a massive inrush of water from an overlying seam.
c. Kottadih panel collapsed because of inadequate support capacity where the support design had been based on data from a single borehole which failed to detect the massiveness of the overlying strata.
d. At GDK-11A Incline in SCCL serious failure of Longwall units took place because of inadequate support capacity.
Flawed Planning
Longwall technology has not been able to take its roots in Indian coal industry soil or establish itself as a preferred system primarily because of flawed planning in the first generation powered support Longwall faces.
Instead of providing a conducive seed bed to germinate, to be absorbed and transferred, and then diffused, a large majority of Longwall faces was commissioned at sites where conditions were singularly adverse right from inception. In Seetalpur Longwall face, quite apart from the adverse mining conditions at the face, such as gassiness, and intrusion in the coal seam, the face performance was baulked by the outbye coal clearance capacity with multiple conveyors which constituted weak links in the evacuation system. The Gleithobel plough installed at Moonidih colliery in 1988 could work only two panels due to non-availability of suitable working areas. The coal seam hardness, structure and other workability indices were difficult for ploughing. Many of the sites selected for Longwall application were replete with adverse geological conditions, constrained by panel size and coal clearance system.
In general, the parameters of Longwall technology were driven by equipment manufacturers under tied aids and no serious efforts were made by Indian planners to vet the plans, including the equipment specifications, keeping in view the then state-of-theart of Longwall technology. In the process, the coal industry was saddled with technology packages which were backdated (archaic?) in some cases, and often a complete mismatch with the site factors. There was no conscious effort either in choosing the best equipment or proven advanced mining technology. The mix of Longwall equipment, from British, German, Russian and Chinese suppliers compounded the problems.
Management Deficiencies
Indian coal industry failed in effective management of Longwall technology which could have opened a new window of opportunity for underground production and productivity and improving the bottom line. Bereft of a management vision to re-engineer the industry for a new Longwall culture and technological transformation, the Industry has been hesitant and cringed resorting to the syndrome of ‘it does not work here’ instead of aggressively addressing the technological concerns of Longwall technology and adopting best practices. In fact coal industry failed to look out of the box. The research and academic institutions also failed in providing the necessary technical support to ensure successful transfer of high-tech Longwall technology. If management is ‘the art of getting things done’, the coal industry failed in providing the right seed bed for sowing, germinating and transferring Longwall techno-logy vis-a-vis the exemplar of Chinese coal industry.
WHERE DO WE GO FROM HERE — RETHINKING LONGWALL
What are the implications of this analysis? The under-performance of Longwall technology to date should call for a changed mindset of the coal industry refocusing on the key success factors for Longwall. More importantly, if the learning curve for this new technology for Indian coal industry has been unduly long and protracted, it is necessary to catch up by looking out of the box and learning from international best practices. In the longer term future, beyond 2015 perhaps, the predominance of surface mining will wane and production from the underground sector based on Longwall will provide the succour for shoring up coal production. There is much that Indian coal industry can learn from Chinese experiences in Longwall technology, especially for thick seam mining using sub-level caving. If high performance Longwall is a reality in China, the USA and Australia, the coal industry must accept the challenge of transplanting the international best practices into India with more effective face management on a consistent basis, through detailed evaluation of Longwall site factors and focus on increased utilization.
REFERENCES
[1] R Knapp. ‘Survey of Energy Resources 2001.’ World Energy Council, London 2001.
[2] G Doyle. ‘China’s Potential in International Coal Trade.’ IEA Coal Research, October 1987.
[3] A K Ghose. ‘Design of Longwall Faces in India — Agenda for Decisions.’ Journal of Mines, Metals & Fuels, March, 1985, pp 67-74.
[4] D Zhai and Y Wang. ‘A Review of Development of China’s Coal Industry in the New Millennium.’ Journal of Mines, Metals & Fuels, June 2001, pp 204-211.
中文譯文
印度的長(zhǎng)壁采煤法為什么沒(méi)有像在中國(guó)這樣的
發(fā)展中國(guó)家一樣取得成功
A K Ghose教授
摘要 在2000~2001年期間全球約生產(chǎn)了33億噸的煤炭,中國(guó)在所有的產(chǎn)煤國(guó)家中排第一,生產(chǎn)了約9.7億噸,印度由于生產(chǎn)了約3.2億噸的煤炭而排名第三。 這些發(fā)展中國(guó)家都有豐富的煤炭資源,根據(jù)世界能源協(xié)會(huì)2001年的能源資源調(diào)查,中國(guó)在1999年末被勘探證明的可采煤有1145億噸,而印度則有843.96億噸。煤炭在中國(guó)和印度的能源經(jīng)濟(jì)中心地位, 煤炭在中國(guó)的能源消費(fèi)中占75% ,而在印度煤炭在商業(yè)能源中消費(fèi)占混合比是 64% 左右。 然而,在兩個(gè)產(chǎn)煤大國(guó)之間對(duì)產(chǎn)煤技術(shù)的任何比較也許是惹人不快的, 當(dāng)然這些比較是不公平的,兩國(guó)的煤炭有不一樣的埋藏條件,不一樣的地質(zhì)情況,以及不一樣的社會(huì)文化和政治環(huán)境。地下采煤在中國(guó)占有94%的比例,然而在印度地下采煤的比例僅僅只有21%。調(diào)查并且分析可以理解的理由,一是要調(diào)查長(zhǎng)壁采煤技術(shù)在兩個(gè)國(guó)家按年代順序的發(fā)展程度,分析兩個(gè)國(guó)家的長(zhǎng)壁采煤技術(shù)并把它放在各自自己的國(guó)情里考慮。這篇文章嘗試用并不明顯的理由去全面分析已經(jīng)存在的事實(shí),對(duì)把主觀的理由作為印度長(zhǎng)壁采煤失敗理由,作為時(shí)間,也僅僅是說(shuō)明大多數(shù)的假設(shè)。它也不總是反應(yīng)計(jì)劃的決定者在選擇采用什么技術(shù)的時(shí)候的眼光。就當(dāng)作它是可能,我們?cè)谶@里分析為什么長(zhǎng)壁采煤在中國(guó)優(yōu)勢(shì)這么明顯,而在印度為什么又這么落后。
關(guān)鍵詞 長(zhǎng)壁采煤;地質(zhì)條件及技術(shù); Moonidih 煤礦;煤田
長(zhǎng)壁采煤技術(shù)的出現(xiàn)及發(fā)展
圖一 從1984年以來(lái)長(zhǎng)壁采煤法的產(chǎn)量(噸)的變化
每8小時(shí)每臺(tái)機(jī)器的產(chǎn)量(單個(gè)礦井的年平均值)
十七世紀(jì)在英國(guó)什羅浦郡出現(xiàn)的長(zhǎng)壁采煤技術(shù)在過(guò)去三個(gè)世紀(jì)已經(jīng)迅速席卷全球,到現(xiàn)在為止長(zhǎng)壁采煤技術(shù)生產(chǎn)的煤炭已經(jīng)占了全球總產(chǎn)量的70%,而且它被認(rèn)為是最安全、產(chǎn)量最高、效率最高的一種采煤方法。長(zhǎng)壁采煤法第一次在印度出現(xiàn)大概在1870年左右,但是在印度很早出現(xiàn)的長(zhǎng)壁采煤技術(shù)在其煤炭行業(yè)的發(fā)展卻出奇的慢而且停止。自從第一次嘗試運(yùn)用長(zhǎng)壁采煤法以后,長(zhǎng)壁采煤法只有在1960年左右及第一次機(jī)械化時(shí)才被采用,新的長(zhǎng)壁采煤法在1978年的 Moonidih Colliery才被應(yīng)用。雖然這次在印度采煤技術(shù)相對(duì)落后的情況下開(kāi)始了印度的長(zhǎng)壁采煤技術(shù),盡管有印度煤炭部和煤炭協(xié)會(huì)的支持,但是印度的長(zhǎng)壁采煤技術(shù)仍然落后于世界上運(yùn)用長(zhǎng)壁采煤技術(shù)好的國(guó)家。一個(gè)可以引證的例子就是2000年的美國(guó)59個(gè)采用長(zhǎng)壁采煤法的煤礦中的14個(gè),它們的平均產(chǎn)量是每臺(tái)機(jī)器平均每8小時(shí)凈產(chǎn)8100噸的煤。圖一表示了從1984年開(kāi)始的長(zhǎng)壁采煤法的產(chǎn)量(噸)的變化,每8小時(shí)每臺(tái)機(jī)器的產(chǎn)量(單個(gè)礦井的年平均值)。如此高的產(chǎn)量的在美國(guó)、澳大利亞甚至中國(guó)都有例子。
為了給比較中國(guó)和印度長(zhǎng)壁采煤技術(shù)的發(fā)展提供背景,調(diào)查中國(guó)和印度的采煤技術(shù)發(fā)展是很必要的。印度在1947年獲得了獨(dú)立,在195 1年開(kāi)始重新建設(shè)國(guó)家經(jīng)濟(jì)。圖一表示自從1984年的每8小時(shí)長(zhǎng)壁采煤法的產(chǎn)量(平均產(chǎn)量每單位時(shí)間)。中國(guó)自從1949年開(kāi)始獨(dú)立,它的煤炭出口量是3243萬(wàn)噸,非常接近印度的煤炭出口量。
雖然兩個(gè)國(guó)家都是在同一個(gè)非常差的水平下開(kāi)始的,但中國(guó)的煤炭產(chǎn)量已經(jīng)經(jīng)過(guò)幾次跳躍在1997年達(dá)到了13億噸的產(chǎn)量,這里面包括國(guó)有煤礦、地方性的煤礦、集體煤礦及私人的小煤礦。自從那以后中國(guó)開(kāi)始一系列的小煤礦改革,超過(guò)40000個(gè)小煤礦被關(guān)閉,產(chǎn)量也減少至了2000~2001年的九億七千萬(wàn)噸左右。這也是中國(guó)和印度在長(zhǎng)壁采煤法經(jīng)驗(yàn)之間重要的不同。自從那時(shí)以后,中國(guó)的長(zhǎng)壁采煤方法一直在跳躍發(fā)展,而那時(shí)的印度則還是在人工采煤,裝備了長(zhǎng)壁采煤法的14個(gè)印度煤礦在2000~2001年的產(chǎn)量只有452萬(wàn)噸,而中國(guó)在1997年的已經(jīng)安裝了長(zhǎng)壁采煤機(jī)器的238個(gè)全自動(dòng)化的工作面,平均年產(chǎn)量是784000噸。在1997年,超過(guò)76個(gè)完全機(jī)械化長(zhǎng)壁采煤法工作面的年產(chǎn)量的產(chǎn)量超過(guò)了100萬(wàn)噸,其中有12個(gè)工作面年產(chǎn)量超過(guò)了200萬(wàn)噸。在1999年的時(shí)候,山東省兗州煤礦的一個(gè)采煤隊(duì)一年產(chǎn)量是512萬(wàn)噸。拿中國(guó)和印度的長(zhǎng)壁采煤法進(jìn)行對(duì)較是很不公平的。在1978~1985年之間,大約有200套長(zhǎng)壁采煤的機(jī)器進(jìn)口到中國(guó),技術(shù)的發(fā)展不僅使中國(guó)的煤炭產(chǎn)量增加了,而且促使機(jī)器進(jìn)口的增加和國(guó)內(nèi)機(jī)器產(chǎn)量增加了7個(gè)百分點(diǎn)。在1980年,中國(guó)大概有75%的完全機(jī)械化的長(zhǎng)壁采煤機(jī)器是進(jìn)口的,到了1985年由于有了新的技術(shù)的出現(xiàn)以及本國(guó)模仿制造的機(jī)器出現(xiàn),這個(gè)比例下降到了13.86% 。在過(guò)去的三十年中經(jīng)過(guò)的 R&D的不斷支持,中國(guó)的厚煤層長(zhǎng)壁采煤技術(shù)已經(jīng)有了一個(gè)重要的突破性發(fā)展,而且煤炭年產(chǎn)量已經(jīng)進(jìn)入了世界前列,煤炭機(jī)械的制造水平也有進(jìn)步。到了1996年,中國(guó)有86個(gè)完全機(jī)械化的長(zhǎng)壁采煤工作面,年產(chǎn)量達(dá)到了六千七百萬(wàn)噸。
即使表面上中國(guó)落后于美國(guó)和澳大利亞這樣的長(zhǎng)壁采煤法先進(jìn)的國(guó)家,但是有了政府的優(yōu)惠政策,大量的投資用在了進(jìn)口的和本土的工作面裝備上,中國(guó)是在用兩條腿走路,快速的決策和良好的工作文化都有可能讓中國(guó)在落后美國(guó)和澳大利亞長(zhǎng)壁采煤法的情況下開(kāi)始大步的追趕。關(guān)鍵時(shí)候的成功在中國(guó)出現(xiàn)了而在印度卻沒(méi)有出現(xiàn)。在這樣的背景下,“少于適當(dāng)?shù)谋憩F(xiàn)”這是個(gè)委婉的說(shuō)法,這也是印度機(jī)械化缺乏的一個(gè)表現(xiàn)。
為印度長(zhǎng)壁采煤法打分
長(zhǎng)壁采煤法的落后促使高投資出現(xiàn)在了印度長(zhǎng)壁采煤工作面,它的第一次出現(xiàn)是在1978年8月的 Moonidih 煤礦,同時(shí)也有了在過(guò)去25年間對(duì)印度長(zhǎng)壁采煤的思索、反省和關(guān)心。安裝在 Churcha West 煤礦(1989)和 Kottadih 煤礦(1997)的長(zhǎng)壁采煤機(jī)械的崩潰,引起了印度政府和許多國(guó)會(huì)議員的關(guān)注,并成立了好幾個(gè)委員會(huì)來(lái)調(diào)查整個(gè)長(zhǎng)壁采煤法的問(wèn)題和解決辦法。這些委員會(huì)包括 H.B.Ghosh 委員會(huì)(1983~1984), 那是一個(gè)在Shri.K 主席(1988~1989)領(lǐng)導(dǎo)下行動(dòng)的小組;S.K.Chowdhury 委員會(huì)(1990)詢問(wèn)環(huán)境對(duì)長(zhǎng)壁采煤法失敗的影響;最后 Mahendru 委員會(huì)(1998),它要求工作人員學(xué)習(xí)長(zhǎng)壁采煤的知識(shí)以及在印度特殊情況下長(zhǎng)壁采煤的工作方法。
大體而言,那些已經(jīng)被認(rèn)同的印度不長(zhǎng)壁采煤法不成功的因素主要有以下幾個(gè)方面:
1)對(duì)長(zhǎng)壁采煤法現(xiàn)場(chǎng)的不適當(dāng)?shù)牡刭|(zhì)和地理方面的評(píng)估;
2)選用的設(shè)備有缺陷,煤礦通風(fēng)系統(tǒng)的問(wèn)題;
3)計(jì)劃方面的管理不善,輔助系統(tǒng)的不完善,效率不高;
4)長(zhǎng)壁采煤法環(huán)境沒(méi)有形成,而且可以為長(zhǎng)壁采煤法服務(wù)的人事技術(shù)方面,電力驅(qū)動(dòng)補(bǔ)給,材料補(bǔ)給,通風(fēng)補(bǔ)給等方面的不足;
5)缺乏一個(gè)長(zhǎng)壁采煤機(jī)器制造環(huán)境。
所有的這些因素出現(xiàn)或有不好的表現(xiàn)到影響到了印度的煤炭企業(yè)在長(zhǎng)壁采煤技術(shù)方面的信心。在許多的文章中,作者都有在研究印度長(zhǎng)壁采煤法的問(wèn)題,分析問(wèn)題而且精確地發(fā)現(xiàn)了印度采煤法問(wèn)題的主要因素。相關(guān)的印度在深度調(diào)查以后主要表現(xiàn)在以下三個(gè)主要的方面:
1) 地質(zhì)的和地理位置因素
2)計(jì)劃缺陷
3)管理空白。
地質(zhì)的和地理位置因素
28個(gè)長(zhǎng)壁采煤工作面的調(diào)查表明,開(kāi)采前的地質(zhì)和地理位置調(diào)查投資可以避免一些崩潰或者減少生產(chǎn)中的危險(xiǎn),此外還有助于更謹(jǐn)慎地選擇機(jī)器。這里有許多每個(gè)長(zhǎng)壁工作面操作的實(shí)際例子,一些非正道的經(jīng)驗(yàn)包括:
1)工作面在推進(jìn)的過(guò)程中遇到一系列的斷層發(fā)育,在沒(méi)開(kāi)采以前不知道斷層的發(fā)育嗎。
2)在開(kāi)采中的工作面遇到了火的入侵,從一個(gè)地質(zhì)縫合線處澆水。
3)Kottadih 嵌板因?yàn)橹尾蛔《顾?,設(shè)計(jì)時(shí)候是以數(shù)據(jù)為基礎(chǔ)的,在地面上打個(gè)洞不會(huì)發(fā)現(xiàn)那么大的圍巖壓力。
計(jì)劃缺陷
長(zhǎng)壁采煤法之所以沒(méi)有在印度扎根或者形成自己的一套系統(tǒng),是因?yàn)殚L(zhǎng)壁采煤技術(shù)在其第一次出現(xiàn)在印度的時(shí)候就存在著計(jì)劃的缺陷。
剛開(kāi)始提供的并不是一個(gè)有益于種子發(fā)育的層,然后散播,大多數(shù)的長(zhǎng)壁工作面被安排在哪里是另外一種權(quán)力。在Seetalpur的長(zhǎng)壁采煤工作面中,有許多方面就不適合采用長(zhǎng)壁采煤法,比如瓦斯等很多的氣體,還有突出的煤層等等。長(zhǎng)壁采煤機(jī)械在Moonidih的安裝,在1988年只有兩個(gè)區(qū)域可以開(kāi)采。煤層的厚度,構(gòu)造和其它指標(biāo)對(duì)開(kāi)采有很多困難。多數(shù)被選擇為長(zhǎng)壁采煤的地方都有不利的地質(zhì)情況,頂板問(wèn)題以及煤層的間隙問(wèn)題。
總的來(lái)說(shuō),印度的長(zhǎng)壁采煤法是在機(jī)器制造者的利益驅(qū)動(dòng)下開(kāi)始的,并沒(méi)有完整的計(jì)劃和一直的努力在這個(gè)
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