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hydraulic and water functions). At either end of the main body are fitted the ranging arms which can be ranged vertically up down by means of hydraulic rams, and on to which are mounted the shearer cutting drums which are fitted with 40–60 cutting picks. Within the ranging arms are housed very powerful electric motors (typically up to 850 kW) which transfer their power through a series of lay gears within the body and through the arms to the drum mounting locations at the extreme ends of the ranging arms where the cutting drums are. The cutting drums are rotated at a speed of 20–50 revs/min to cut the mineral from coal seam.
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continuous miner units, as the longwall itself is not capable of the initial development. The layout of
Longwall could be either "advancing" type or of "retreat" type. In the advancing type, the gate roads are formed as the coal face advances. In thinner seams the advancing longwall mining method may be used. In the retreat type, the panel is a face connecting them both. Only the maingate road is formed in advance of the face. The tailgate road is formed behind the coal face by removing the
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Many ecosystems rely on the annual consistency of water inputs and outputs, and disturbing these patterns can result in unsustainable conditions for species reliant on water for species reproduction. Longwall mining can also result in localized water temperature change, stimulating algal bloom which
360:
Compared to manual control of the mine equipment, the automated system yields improved production rates. In addition to productivity gains, automating longwall equipment leads to safety benefits. The coal face is a hazardous area because methane and carbon monoxide are present, while the area is hot
238:
mounted on the surface. Other ventilation methods can be used where intake air also passes the main gate and into a bleeder or back return road reducing gas emissions from the goaf on to the face, or intake air travels up the tail gate and across the face in the same direction as the face chain in a
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and water movement in a region where LWMS is heavily done. This is important to consider as some longwall mine sites can span lengths of several kilometers. That being said, hydrological flow systems, root systems from trees, and vegetative species can suffer from the amounts of soil being removed
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Gate roads are driven to the back of each panel before longwall mining begins. The gate road along one side of the block is called the maingate or headgate; the road on the other side is called the tailgate. Where the thickness of the coal allows, these gate roads have been previously developed by
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where a long wall of coal is mined in a single slice (typically 0.6–6.0 m (2 ft 0 in – 19 ft 8 in) thick). The section of rock that is being mined, known as the longwall panel, is typically 3–4 km (1.9–2.5 mi) long, but can be up to 7.5 km (4.7 mi)
445:
disturbing the natural landscape near the mines, the natural water flow paths can be redirected which results in additional erosion across a stream or river bank. Additional mining in concentrated areas continuously move these water flow paths, which take years to return to their original states.
246:
of coal in the goaf area, gases may be allowed to build up behind seals so as to exclude oxygen from the sealed goaf area. Where a goaf may contain an explosive mixture of methane and oxygen, nitrogen injection/inertisation may be used to exclude oxygen or push the explosive mixture deep into the
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Longwall mining has traditionally been a manual process in which alignment of the face equipment was done with string lines. Technologies have been developed which automates several aspects of the longwall mining operation, including a system that aligns the face of the retreating longwall panel
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As the shearer removes the coal, the AFC is snaked over behind the shearer and the powered roof supports move forward into the newly created cavity. As mining progresses and the entire longwall progresses through the seam, the goaf increases. This goaf collapses under the weight of the overlying
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Drive was closed for four weeks because longwall panels ... destabilised the road. In 2000, the State
Government stopped mining when it came within 600 metres from the twin bridges. A year later there were reports of 40-centimetre gaps appearing in the road, and the bridge had to be jacked
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The coal is cut from the coal face by a machine called the shearer (power loader). This machine can weigh 75–120 tonnes typically and comprises a main body, housing the electrical functions, the tractive motive units to move the shearer along the coal face and pumping units (to power both
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Longwall mining has limited available research on the impacts of nearby forests, however emerging satellite imagery studies have shown possible relations to drier surface soil near regions where longwall mining has recently occurred. In addition to drier soils, forest canopy moisture has been
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As a result of bedrock cracking from mining beneath waters such as lakes or rivers, there have been groundwater losses of varying extents. Mines within a few hundred meters of the surface are susceptible to receiving great inputs of water from these bodies. Moreover, after mining interference
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system specially developed for mining. Prior to the chainless haulage systems, haulage systems with chain were popular, where a heavy duty chain was run along the length of the coal face for the shearer to pull itself along. The shearer moves at a speed of 10–30 m/min (33–98 ft/min)
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However, there are several mines, which were successfully mined with little to no measurable surface subsidence including mines under lakes, oceans, important water catchments and environmentally sensitive areas. Subsidence is minimised by increasing the block's adjacent chain pillar widths,
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strata. The strata approximately 2.5 times the thickness of the coal seam removed collapses and the beds above settle on to the collapsed goaf. This collapsing can lower surface height, causing problems such as changing the course of rivers and severely damaging building foundations.
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Since longwall mining is namely, very long, it can effect areas of over 200 acres (81 ha). Over these largest spans, it has been observed that longwall mines underlying mountain sides demonstrate more visible subsidence in mountain landscapes than it does for valley landscapes.
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height to form a roadway that is high enough to travel in. The end of the block that includes the longwall equipment is called the face. The other end of the block is usually one of the main travel roads of the mine. The cavity behind the longwall is called the goaf, goff or gob.
405:, Australia "the surface has dropped by as much as five metres in places" above a multi-level mine. In some cases the subsidence causes damage to natural features such as drainage to water courses or man-made structures such as roads and buildings. "
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method), fewer roof support consumables are needed, higher volume coal clearance systems, minimal manual handling and safety of the miners is enhanced by the fact that they are always under the hydraulic roof supports when they are extracting coal.
271:. An individual chock can weigh 30–40 tonnes, extend to a maximum cutting height of up to 6 m (20 ft) and have yield rating of 1000–1250 tonnes each, and hydraulically advance itself 1 m (3 ft 3 in) at a time.
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to the main gate. Here it is loaded on to a network of conveyor belts for transport to the surface. At the main gate the coal is usually reduced in size in a crusher, and loaded on to the first conveyor belt by the beam stage loader (BSL).
267:, called powered roof supports, chocks or shields, which are typically 1.75 m (5 ft 9 in) wide and placed in a long line, side by side for up to 400 m (1,300 ft) in length in order to support the roof of the
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The AFC is placed in front of the powered roof supports, and the shearing action of the rotating drums cutting into the coal seam disintegrates the coal, this being loaded on to the AFC. The coal is removed from the coal face by a
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of
Northeastern Arizona in the 14th century. Miners undercut the coal along the width of the coal face, removing coal as it fell, and used wooden props to control the fall of the roof behind the face. This was known as the
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and humid since water is sprayed over the face to minimize the likelihood of sparks occurring when the shearer picks strike rock. By automating manual processes, face workers can be removed from these hazardous areas.
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Typically, intake (fresh) air travels up the main gate, across the face, and then down the tail gate, known as 'U' type ventilation. Once past the face the air is no longer fresh air, but return air carrying away
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As of 2014, measures were taken by the
Australian government to mitigate water impacts from longwall mining. Legislative assemblies have called for action to improve mine infrastructure to minimize disturbances.
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Abandoned mines are also an issue with regards to areas where residential development has moved in. Houses erected near abandoned longwall mines face the threat of future damage from sinkholes and poor
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Longwall mining can result in geological disruptions in the rockbed, and can in turn affect water movement and result in water moving away from the surface, through the mined area, and into the
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in 2015 in
British Columbia, causing disputes because of the hiring of foreign workers instead of Canadians and because of its potential impact on the environment. This mine expected to have
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for blasting to drop the face. Once dropped, manual labor was used to load coal on to the conveyor parallel to the face and to place wooden roof props to control the fall of the roof.
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from closed longwall mines can continue for up to fifteen years, however it is possible to measure the volume of potential methane emissions based on water flow in the closed mines.
144:, "one of the last advancing longwall mines in the United States". This longwall mine did not use a conveyor belt, instead relying on ponies to haul coal tubs from the face to the
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into the environment, however the increase of a typical longwall mine face from 200 to 300 metres (660 to 980 ft) was not found to release significantly more methane.
783:
Einicke, G.A.; Ralston, J.C.; Hargrave, C.O.; Reid, D.C.; Hainsworth, D.W. (December 2008). "Longwall Mining
Automation. An Application of Minimum-Variance Smoothing".
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goaf where there are no probable ignition sources. Seals are required to be monitored each shift by a certified mine supervisor for damage and leaks of harmful gases.
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Longwall mining, in which broad panels of coal a few metres high and hundreds of metres wide are bored out of the earth, causes ground above the mines to subside.
1038:
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Canada has some of the largest coal reserves in the world, and until 2013 there had been no longwall mines in Canada for over 25 years. A mine was opened by
818:
Einicke, G.A.; Malos, J.T.; Reid, D.C.; Hainsworth, D.W. (January 2009). "Riccati
Equation and EM Algorithm Convergence for Inertial Navigation Alignment".
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decreasing extracted block widths and heights, and by giving consideration to the depth of cover as well as competency and thickness of overlying strata.
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The shearer is carried along the length of the face on the armoured face conveyor (AFC); using a chain-less haulage system, which resembles a ruggedised
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33:
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and smoothers can be applied to improve the dead reckoning estimates prior to repositioning the longwall equipment at the completion of each shear.
861:
1039:"Potential Management and Rehabilitation Requirements of Environmental Effects From Longwall Subsidence on Streams, Lakes and Groundwater Systems"
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1011:"Fact sheet - Subsidence from longwall coal mining | Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development"
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637:
1084:"Prediction of Longwall Methane Emissions: An Evaluation of the Influence of Mining Practices on Gas Emissions and Methane Control Systems"
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as "the conveyor method" of mining, after the most prominent piece of machinery involved. Unlike earlier longwall mining, the use of a
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method of mining. While the technology has changed considerably, the basic idea remains the same, to remove essentially all of the
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Such low-technology longwall mines continued in operation into the 1970s. The best known example was the New
Gladstone Mine near
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in the late 17th century, although it may have been anticipated in the pre-industrial era by a similar technique utilized by the
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Longwall and room and pillar methods of mining can both be used for mining suitable underground coal seams. Longwall has better
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As with many mining techniques, it is important to consider the local and regional environmental impacts from longwall mining.
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parallel to the coal face forced the face to be developed along a straight line. The only other machinery used was an
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Longwall mining has already resulted in substantial damage to riverbeds, swamps and water catchments in the area
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can be used to estimate the unknown filter and smoother parameters for tracking the longwall shearer positions.
663:, a documentary film, Les Benedict, director, Steve Knudston, producer, 1972. Available on YouTube in 3 parts
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There have been cases of surface subsidence altering the landscape above the mines. At
Newstan Colliery in
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572:, Office of Coal, Nuclear, Electric and Alternate Fuels, U.S. Department of Energy, March 1995, pp. 9–10.
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On top of this, if there are present dams near to the longwall mining site, this could doubly impact the
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to collapse into the void behind, while maintaining a safe working space along the face for the miners.
381:(LWMS) is an anthropogenic process that has many ecological and environmental impacts, particularly on
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The Cerro
Colorado Site and Pithouse Architecture in the Southwestern United States Prior to A.D. 900
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Starting around 1900, mechanization was applied to this method. By 1940, some referred to longwall
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Illinois Department of Natural Resources, Illinois State Geological Survey, Circular 573, 2008
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as it would have a reduced inflow rate as well as the loss to the underlying rock fracturing.
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Plan of longwall mine before conveyors – the hoist is at the center of the central pillar.
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University of Wollongong & the Australasian Institute of Mining and Metallurgy
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emissions of 17 megatons per year; however, a carbon cap was placed on it by the
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1061:"Assessing Longwall Mining Impacts on the Forests Above « Landsat Science"
683:"Longwall Mining, Underground Coal Mining, Mining Techniques, Mining Companies"
430:. A resulting loss in surface water can negatively impact riparian ecosystems.
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Longwall mining has been extensively used as the final stage in mining old
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warned that "subsidence could happen suddenly and occur over many years".
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862:"Study measures the environmental impacts of longwall mining subsidence"
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sideways to realign it." A 2005 geotechnical report commissioned by the
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982:"IMPACTS OF LONGWALL COAL MINING ON THE ENVIRONMENT IN NEW SOUTH WALES"
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mines. In this context, longwall mining can be classified as a form of
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Planned Coal Mine Subsidence in Illinois: A Public Information Booklet
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1179:"B.C.'s first underground coal mine in more than 25 years approved"
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Oklahoma advancing longwall mine c. 1917; arrows show airflow
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News and information resource dedicated solely to longwall mining
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McCall, F. E.; Garcia, F.; Trevits, M. A.; Aul, G. (1993-12-31).
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BHP Billiton Mitsubishi Alliance (2005) accessed 19 December 2011
552:. Cambridge, Massachusetts, USA: The Peabody Museum. p. vi.
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Iowa Underground: a guide to the state's subterranean treasures
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can use up available oxygen required for other species health.
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1156:"Initial pitch for Murray River did not use longwall mining"
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Iowa's geological past: three billion years of earth history
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beneath them, and these stresses lead to surface erosion.
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from a broad coal face and allow the roof and overlying
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Mining Technology | Mining News and Views Updated Daily
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calculation to estimate the shearer positions. Optimal
632:. Black Earth, Wis.: Trails Books. pp. 119–120.
601:. Iowa City: University of Iowa Press. p. 258.
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of the coal. Return air is extracted by ventilation
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West Virginia retreating longwall mine c. 1917
97:The basic idea of longwall mining was developed in
81:long and 250–400 m (820–1,310 ft) wide.
498:to keep the emissions at 500,000 tonnes per year.
394:, even up to thirty years after mine abandonment.
290:Chocks providing support to allow shearer to work
148:where a hoist hauled the tubs to the surface.
133:cutter to undercut the coal face and electric
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915:"Longwall mine plan a threat to water supply"
753:
751:
466:Longwall mines have been observed to release
8:
1109:Methane gas emissions during longwall mining
951:"Risk to life, but more mining under bridge"
890:"Final Report - Effects of Longwall Mining"
761:. Illinois Coal Association. Archived from
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1250:
1242:
1207:. Educational resource on longwall mining.
1131:"Countries with the biggest coal reserves"
710:. University of Wollongong. Archived from
1236:The Mine Subsidence Technological Society
49:of all important aspects of the article.
731:Mine Safety and Health Administration
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324:(about 80% compared with about 60% for
316:Comparison with room and pillar method
278:Hydraulic chocks, conveyor and shearer
45:Please consider expanding the lead to
1238:The Institute of Engineers, Australia
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1205:University of Wollongong (Australia)
546:Bullard Jr., William Rotch (1962).
528:Glossary of coal mining terminology
355:Expectation-maximization algorithms
338:perpendicularly to the gate-roads.
1218:Hidden Costs of Clean Coal Project
14:
949:Frew, Wendy (November 20, 2007).
299:depending on cutting conditions.
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23:
1220:The Center for Public Integrity
1049:: 117–124 – via Geoterra.
37:may be too short to adequately
16:Form of underground coal mining
47:provide an accessible overview
1:
785:IEEE Control Systems Magazine
412:Roads & Traffic Authority
422:Fracturing and water quality
1224:International Longwall News
595:Anderson, Wayne I. (1998).
496:Canadian federal government
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820:IEEE Trans. Signal Process
583:Ten Minutes in a Coal Mine
343:Inertial navigation system
913:Cubby, Ben (2009-06-10).
76:is a form of underground
989:Total Environment Centre
840:10.1109/TSP.2008.2007090
708:"Homotropal Ventilation"
581:A. Paxton, J. A. Biggs,
458:observed to be reduced.
1015:iesc.environment.gov.au
797:10.1109/MCS.2008.929281
628:Brick, Greg A. (2004).
222:and mine gases such as
345:outputs are used in a
305:scraper chain conveyor
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1230:Mine Subsidence Board
955:Sydney Morning Herald
920:Sydney Morning Herald
365:Environmental impacts
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242:To avoid spontaneous
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1183:www.vancouversun.com
1037:Dawkins, A. (2003).
759:"Underground Mining"
1320:Mountaintop removal
894:www.dep.state.pa.us
832:2009ITSP...57..370E
435:riparian ecosystems
239:homotropal system.
230:, depending on the
1478:Underground mining
661:The Last Pony Mine
568:2009-08-17 at the
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1210:Bauer, Robert A.
866:Australian Mining
743:"LONGWALL MINING"
639:978-1-931599-39-9
585:, 1940, pp. 16–24
476:Methane emissions
449:Ecosystem impacts
322:resource recovery
142:Centerville, Iowa
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764:
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127:conveyor belt
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1186:. Retrieved
1182:
1159:. Retrieved
1150:
1139:. Retrieved
1137:. 2013-11-20
1134:
1125:
1108:
1102:
1091:. Retrieved
1087:
1064:. Retrieved
1055:
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1018:. Retrieved
1014:
1005:
995:February 14,
993:. Retrieved
988:
965:
959:. Retrieved
954:
931:
925:. Retrieved
918:
908:
897:. Retrieved
893:
870:. Retrieved
868:. 2010-04-27
865:
856:
823:
819:
813:
791:(6): 28–37.
788:
784:
778:
767:. Retrieved
763:the original
738:
727:
716:. Retrieved
712:the original
702:
690:. Retrieved
687:Great Mining
686:
677:
660:
656:
629:
623:
612:. Retrieved
597:
590:
577:
558:
548:
541:
523:Strip mining
518:Slope mining
513:Shaft mining
508:Drift mining
485:
465:
456:
452:
443:
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432:
425:
416:
407:Douglas Park
400:
396:
392:soil quality
388:
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281:
263:A number of
262:
241:
216:
198:
150:
139:
120:
96:
73:
72:
52:
36:
34:lead section
1473:Coal mining
1447:Prospecting
1329:Sub-surface
1088:www.cdc.gov
470:, a common
468:methane gas
383:soil health
213:Ventilation
78:coal mining
1467:Categories
1357:Directions
1275:techniques
1188:2020-12-29
1161:2019-04-10
1141:2019-04-10
1093:2019-04-10
1066:2019-04-10
1020:2019-04-10
961:2010-06-02
927:2010-06-02
899:2019-02-09
872:2019-02-09
769:2014-05-24
718:2014-05-24
692:1 February
614:2010-06-05
379:subsidence
373:Subsidence
333:Automation
244:combustion
108:Shropshire
55:March 2021
1437:Automated
1432:Abandoned
1348:Soft rock
1343:Hard rock
1295:Quarrying
488:HD Mining
482:In Canada
341:Briefly,
269:coal face
251:Equipment
220:coal dust
39:summarize
1407:Longwall
1384:Borehole
1379:Bell pit
1310:Dredging
1290:Open-pit
805:36072082
648:3314195M
566:Archived
502:See also
131:electric
1412:Retreat
1394:Stoping
1336:Classes
1282:Surface
848:1930004
828:Bibcode
428:aquifer
232:geology
224:methane
99:England
85:History
1305:Placer
1273:Mining
1117:143760
1115:
846:
803:
671:part 3
668:part 2
665:part 1
646:
636:
605:
204:above
163:Layout
135:drills
123:mining
1425:Other
1374:Shaft
1369:Slope
1364:Drift
1300:Strip
985:(PDF)
844:S2CID
801:S2CID
534:Notes
202:stone
146:slope
1113:OSTI
997:2019
694:2019
634:ISBN
603:ISBN
236:fans
206:coal
116:rock
112:coal
103:Hopi
836:doi
793:doi
1469::
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
