
	Where results make sense

Topic: Longwall mining

In the News (Sat 28 Nov 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	How longwall mining works (Site not responding. Last check: 2007-10-13)
		Longwall mining is a full extraction technique that became commonplace in southwestern Pennsylvania after 1980 and causes subsidence to begin almost immediately and continue for months afterward.
		The longwall mines operate almost exclusively in the Pittsburgh seam -- called the richest mineral deposit in the world -- that runs relatively flat, 300 to 800 feet underground, throughout southwestern Pennsylvania and adjacent states.
		Longwall machines use self-advancing hydraulic systems to keep the mine roof from collapsing as a rotating steel-toothed cutter runs along the coal face, breaking away coal that falls onto a conveyer belt and is transported to the surface.
	www.post-gazette.com /pg/03327/242933.stm (451 words)

	Longwall mining - Wikipedia, the free encyclopedia
		Longwall mining is form of underground coal mining where a long wall (about 250-400 m long typically) of coal is mined in a single slice (typically 1-2 m thick).
		The longwall "panel" (the block of coal that is being mined) is typically 3-4 km long and 250-400 m wide.
		An advantage of longwall mining is that over 80 percent of the coal is recovered, compared with about 50 percent for the more traditional room and pillar method [2].
	en.wikipedia.org /wiki/Longwall_mining (350 words)

	Coal mining - Wikipedia, the free encyclopedia
		Coal mining is the extraction of coal from the Earth for use as fuel.
		Longwall mining is conducted along the seam with the use of self-advancing hydraulic roof supports known as "chocks" or "shields".
		Highwall mining is a form of coal mining in which a continuous miner is controlled remotely from outside the mine, and is guided along the seam straight back drilling holes in excess of 500 feet.
	en.wikipedia.org /wiki/Coal_mining (995 words)

	Wetlands and Longwall Mining
		Longwall mining is most effective where the coal seam is of uniform thickness (as the Pittsburgh seam tends to be) and where the seam has been unaffected by any previous mine activity.
		Longwall mining clearly is the technology of choice for the foreseeable future in southwestern Pennsylvania, and hundreds of thousands of additional acres are at stake.
		Mine operators are reluctant to do this because (a) it requires that more of the natural resource be left in the ground, and (b) it interrupts the efficient flow of the longwall operation and thereby adds to its costs.
	www.rayproffitt.org /longwall/minereport5.htm (5397 words)

	Illinois Coal Association (Site not responding. Last check: 2007-10-13)
		To extend the waiver contained in the deed to longwall mining methods, which entails the certainty of subsidence, would be imposing upon the grantor of the waiver a far greater burden than he originally bargained for.
		The court noted that insofar as longwall mining was different from underground mining techniques known at the time of severance, it was different only in the degree of damage, not the kind of damage, it causes to the surface.
		Longwall equipment, costing millions of dollars, is installed only after very large coal fields, often many square miles, are completely under the control of the coal company so that it can confidently plan mining by the longwall method.
	www.rhinelaw.com /ica.html (4016 words)

	Longwall mining machine - Patent 4155598
		A longwall mining machine incorporates breaking apparatus comprising an underframe which may be an integral extension of the main underframe of the machine and which is mounted on the conveyor for movement therealong, such that the breaking apparatus is rigidly secured to, and comprises an integral part of, the mining machine.
		A mining machine according to claim 1, wherein the rotary element is mounted with its axis of rotation vertical, the upper end of the rotary element being the driven end and the lower end being supported by a bearing in the underframe of the breaking apparatus.
		A mining machine according to claim 6, wherein the breaking apparatus includes a transmission unit comprising an input drive shaft coupled to be driven by said motor unit and an output driven shaft to which the rotary breaking element is coaxially and directly coupled.
	www.freepatentsonline.com /4155598.html (1524 words)

	History and Methods of Longwall Mining (Site not responding. Last check: 2007-10-13)
		In longwall mining, large rectangular blocks of coal are defined during the development stage of the mine and are then extracted in a single continuous operation.
		Longwall mining is increasing in application to coal winning in Australian Underground mining operations.
		The mechanised method of longwall mining was first introduced to Australia in 1963 and currently there are 31 longwall faces operating in Australia.
	www.uow.edu.au /eng/current/longwall/history.htm (391 words)

	Longwall Mining (Site not responding. Last check: 2007-10-13)
		Longwall mining is a highly productive underground mining method in which a panel or block of coal sometimes 1,000 feet wide and two or three miles long is completely extracted.
		With the use of a longwall system, the amount of coal which is recovered in a given area increases from 50% to as much as 80% where geology is favorable.
		With the longwall operation such ground movements are completed in a shorter period of time and the settling process occurs in a more uniform and predictable manner helping to minimize surface impacts.
	www.coalleader.com /longwall_mining.htm (343 words)

	What is Longwall Mining?
		Longwall mining machines are about 800 feet (240 meters) in width and 5 to 10 feet (1.5 to 3 meters) tall.
		Longwall miners extract "panels" - rectangular blocks of coal as wide as the mining machinery and as long as 12,000 feet (3,650 meters).
		Longwall mining replaces the historical "room-and-pillar method", whereby underground "rooms" of coal are manually extracted and pillars are left to support the roof so miners can work safely.
	www.wisegeek.com /what-is-longwall-mining.htm (360 words)

	DEP says value of surface properties unaffected by longwall mining
		Although longwall mining causes widespread and immediate land subsidence that has cracked foundations, split walls, broken windows and destroyed some homes and water supplies, according to the report, no significant difference was found in the value of houses undermined by longwall operations between 1993 and 2002 when compared to similar homes that were not undermined.
		Properties located on or near longwall mining are more likely to receive assessment reductions, and that while the total reductions to date represent only a small portion of the tax base, the average per acre value is lower in the undermined areas.
		Proximity to longwall mining is not as important as a number of factors, such as location of public utilities, schools, parks, recreation facilities and businesses, that affect property value.
	www.post-gazette.com /localnews/20021214longwallreg2p2.asp (939 words)

	Methods of Mining. University of Kentucky
		According to the Kentucky Department of Mines and Minerals, 131.8 million tons of coal was mined in Kentucky in 2000; 62 percent (81 million tons) was from underground mines and 38 percent (50 million tons) was from surface mines.
		Shaft mines are the deepest mines; a vertical shaft with an elevator is made from the surface down to the coal.
		Contour mines are surface mines that mine coal in steep, hilly, or mountainous terrain.
	www.uky.edu /KGS/coal/coal_mining.htm (716 words)

	Longwall Projects
		Kaiser Coal, Raton, NM The impact of the number of gateroad entries on the stability of longwall mining in two-seam mining was evaluated for layouts using two to three entries and "yield" pillars based on field measurements and computer analyses.
		The impact on longwall mining on surface subsidence and stream flow was evaluated for two-seam mining, and assistance provided in layout design for a newly acquired property.
		Measurements of roof movements and entry closures along four longwall panel gateroads and one room-and-pillar panel were integrated to establish simple, practical measurements for the detection of roof instabilities in coal mines.
	www.agapito.com /longwall_projects.htm (1385 words)

	On Mining by Longwall -- 1862
		The "longwall" system of working, then, when properly carried out, is simply the excavation of a large block or pillar of coal, the "winning" out walls being the only parts where "shearings" or "cuttings" require to be made.
		The great difficulty in coal mining was the tender roof, which prevented the lessee in many cases from working by longwall, as it increased the danger of the strata overlying the coal sinking.
		William Dixon, the coalmaster, was the first, he believed, who worked mines on the longwall system, in Scotland at all events, and he in some instances adopted the plan also of going back and taking out all the stoops the roof might be supported with.
	www.westwatermining.com /long1862/long1862.html (3790 words)

	Underground Mining: Longwall Mining (Site not responding. Last check: 2007-10-13)
		There are about 100 longwall operations in the United States, most of them in UMWA mines in Appalachia.
		In longwall mining, a cutting head moves back and forth across a panel of coal about 800 feet in width and up to 7,000 feet in length.
		Longwall mining is done under hydraulic roof supports (shields) that are advanced as the seam is cut.
	www.umwa.org /mining/lwmine.shtml (104 words)

	Longwall Mining 101 (Site not responding. Last check: 2007-10-13)
		Longwall mining, a type of mining practice considered "full extraction," nets more coal with fewer miners than traditional techniques and causes extensive damage to the residences and water supplies of those living above the mines.
		The area where coal is mined is known as a "panel." Full extraction occurs when all the coal is removed and none is left to support the mine roof and land surface.
		Although longwall mines are safer than conventional underground mines in terms of roof collapses, they can produce more dust and more serious air quality problems for workers.
	www.buckeyeforestcouncil.org /mj/Winter1999/Articles/mj13longwall.html (730 words)

	Hook plough apparatus for longwall mining - Patent 4013320
		The mined material, after being cut from the mining face, falls onto a longitudinal conveyor operating within the mining shield, and is then conveyed from the mining face to suitable collecting means operating at the ends of the face for ultimate conveyance through a shaft to the ground surface.
		Another problem with longwall coal mining which has been alleviated by the fixed arch shield technique is the necessity of using long, heavy chains stretched the full length of the longwall face for the transmission of power to propel the mining machines along the mine face.
		Since the arch sections 14 are individually advanceable toward the mining wall M as the mining machine progresses, there is always a possibility that one of the arch sections 14 would be misaligned with respect to the remainder of the arch sections.
	www.freepatentsonline.com /4013320.html (3624 words)

	Final Report - Effects of Longwall Mining
		Longwall mining was first used in Europe where it was found to be safer for miners and more efficient at extracting coal in mines where the equipment could be used.
		The longwall mines tend to be located in less densely populated areas of the counties.
		Because longwall mining is designed to remove large blocks of coal completely and leave no coal behind to support the surface, longwall mining results in larger areas of subsidence troughs than conventional room-and-pillar mining.
	www.dep.state.pa.us /dep/deputate/minres/Longwall/report02/finalreport.htm (7924 words)

	CorpWatch : US: Farmers Fear Coal Mining Will Sink Land
		Longwall dispenses with any attempt to shore up the earth when coal is dug away as mine equipment eats through the substrata.
		Longwall backlash is rubbing emotions raw in Montgomery County, south of Springfield, Ill., pitting rural residents against city dwellers and neighbors against neighbors.
		Other longwall mines have engendered complaints, but state and industry experts say they have never seen anything like the protest in Montgomery County, where opponents insist that the environmental impact will be more acute because the topography tends to be much flatter.
	www.corpwatch.org /article.php?id=14133 (1137 words)

	Wetlands and Longwall Mining -- Executive Summary
		Pennsylvania wetlands are being destroyed by the high-extraction (longwall) mining of bituminous coal underground.
		The surface movement above longwall mine panels is comparable to a slow-moving but major earthquake, and its effects on wetlands, buildings, and roads are devastating to a far greater degree than those of traditional room-and-pillar mining.
		The damage from longwall mining may not be obvious to travelers passing through the scenic landscape of Washington and Greene Counties, unless they happen to be caught in a traffic jam on a subsidence-damaged highway.
	www.rayproffitt.org /longwall/execsumm.htm (1783 words)

	Alteration of habitat following subsidence due to longwall mining as a key threatening process - fact sheet
		Longwall mining is an underground coal mining technique which involves removing a portion of an underground coal seam.
		The extent of subsidence is influenced by various factors, including the width and depth of the longwall mine, topography, the type of overlying rock layers, the design of the mine and the location of the mine.
		Threatened species and ecological communities are known to occur in areas affected by subsidence due to longwall mining, and their habitats are likely to be altered by subsidence and mining-associated activities.
	www.nationalparks.nsw.gov.au /npws.nsf/Content/longwall_mining (775 words)

	The Oil Drum \| Longwall Mining of coal
		The mining process is thus that first the shearer moves down the coal face, grinding off the coal to a depth of around 2 ft. After it passes, the rams on the roof supports, in turn, are released, so that they drop away from roof contact.
		Every mine is different, I was fortunate in that most of those I worked at were quite warm and dry, but my father worked one that was very wet, and, being shallow, also cold.
		But in most mines in the US there is enough room to walk upright, and they tend to be quite comfortable as long as you don't have claustrophobia.
	www.theoildrum.com /story/2006/1/22/23527/4087 (2482 words)

	International Longwall News - Home
		RIO Tinto will cut 160 jobs at its Tarong mine in Queensland, as the ongoing drought has forced the Tarong power station to cut electricity generation by 70% to save water, which in turn means less coal usage.
		DRAEGER Safety told International Longwall News yesterday that the independent test of the Oxyboks K self-rescuer units used during the Oaky Creek evacuation earlier this month has found they were not faulty, but the coal miners' union says further tests are needed.
		LONGWALL coordinators are now commanding up to $A140,000 in Queensland and $150,000 in New South Wales and undermanager deputies are being paid up to $160,000 in NSW, according to the 2007 Hays Salary Survey.
	www.longwalls.com (871 words)

	Murray defends company's longwall mining practice - PittsburghLIVE.com
		Longwall mining a source of grief for DEP officials
		Longwall mining involves the total extraction of the coal.
		State Act 54 of 1994, which allows coal companies to mine beneath homes and other structures built before 1966, as long as property owners are compensated for subsidence damage and water loss.
	pittsburghlive.com /x/valleyindependent/news/charleroi/s_267584.html (624 words)

	Mining Technology - longwall coal mine - Twentymile - Colorado
		Peabody installed a new longwall system at the mine during 2006, with the aim of increasing its output to 10.9Mt/y by 2008.
		The first nine longwall panels, which were extracted between 1989 and 1996, were located in the western area of the mine, with the output since then coming from the eastern area.
		The mine is serviced by Union Pacific, which runs two or three, 105-car trains each carrying 10,000t per day to power stations in Colorado and as far away as Kentucky, Georgia and northern Mexico.
	www.mining-technology.com /projects/twentymile (909 words)

	ACHP \| Prominent Section 106 Cases: Summer 2001
		Longwall mining is a method that causes rapid surface subsidence, as temporary roof supports in a mine are removed as coal mining machinery moves forward.
		The focus of consultation was on whether the longwall mining, which will pass directly beneath the farm structures, would result in irreparable damage, and, if so, whether proposed repairs or rehabilitation could occur in such a manner to preserve the property’s historic integrity.
		In October 2000, OSM determined that the permit issued by PADEP for longwall mining under the Thomas Kent Jr., Farm was defective and was not a valid authorization to conduct mining since it would adversely affect the farm’s historic properties through subsidence.
	www.achp.gov /casearchive/casessum01PA.html (964 words)

	Mining Engineering at WVU
		Modern longwall coal mining, first introduced to the United States in the mid-1950s, is the most recent mining technique.
		Longwall productivity is at least five times that of the commonly used room and pillar method, and is at least 200 times safer in terms of fatalities and lost-time injuries.
		Longwall mining requires a large capital investment, complicated by an existing uncertainty regarding the applicability of the technique and its environmental effects.
	www2.cemr.wvu.edu /~wwwmine/research/rescenter/longw_grd/longctr.html (736 words)

	longwall mining (Site not responding. Last check: 2007-10-13)
		Proceedings of the Symposium on Geology in Longwall Mining, Nov 1996.
		Long wall Mining Instead of coal pillars, the longwall mining system uses a line of moving hydraulic jacks to support the roof temporarily in the mining area.
		In the case of longwall mining of coal, self-advancing roof supports, made of hydraulic jacks and metal plates, are moved ahead, allowing the ceiling in the mined area to cave in as the miners work...
	www.gominingnow.info /longwallmining (643 words)

	Mining Technology - Longwall coal mine - SUFCO - Utah
		The mine is located in the Wasatch Plateau coalfield, producing coal from the Upper Hiawatha seam hosted in the cretaceous-age Blackhawk formation.
		Remaining longwall reserves are limited in the mine's existing leases, with the last seven panels containing an estimated 41.0Mt of recoverable coal.
		Longwall mining was first used at SUFCO in 1985 with the current face equipment installed in 1998.
	www.mining-technology.com /projects/sufco (807 words)

Try your search on: Qwika (all wikis)