after mining SUBSIDENCE PRODUCED BY LONGWALL COAL MINING The mechanical aspects of the subsidence pro 173 cess in flat lying coal bearing rocks mined by longwall methods are reasonably well known compared to room and pillar mining and are documented abundantly in the literature This knowledge may be summarized as followsPARAMETRIC STABILITY ANALYSIS OF ROOM AND PILLAR METHOD IN DEEP COAL MINES Wael Rashad Elrawy Abdellah Mining Metallurgical Eng Dept Faculty of Engineering University of Assiut Assiut Egypt E mail address wre544 gmail waelabdellah aunedueg Received 14 January Accepted 24 February ABSTRACT
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Types of Underground Mining Underground mining for coal is conducted by either room and pillar mining or longwall mining In room and pillar mining approximately 50 percent of the coal is removed using a continuous miner from areas known as rooms The rest of the coal is left in place in the form of pillars that hold up the roof and prevent The room and pillar system is used in mining coal iron and copper ores mainly when found as manto or blanket sediments stone and aggregates talc soda ash and potash The key to the winning room and pillar mining is opting the optimum pillar size If the pillars are so small the mine will fall down
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Figure 2 shows longwall and room and pillar mining methods The orange highlighted areas with hatching are mined longwall panels The blue highlighted areas are the pillars or areas of solid coal The areas around the longwall panel have been mined using the room and pillar method of mining as shown in Figure 1 Text Featur Figure 3Feb 27 32 This method is sometimes called room and pillar mining This can be better understand with the help of follwing fig 6 APPLICABILITY OF BORD AND PILLAR METHOD The Bord and Pillar method is adopted for working 1 A seam thicker than 15 m 2 A seam free from stone or dirt bands
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Once coal is extracted from an area the roof is allowed to collapse in a controlled fashion Room and Pillar Mining Room and pillar mining is effective for small blocks of thinner coal seams In room and pillar mining a network of rooms is cut into the coal seam leaving a series of pillars of coal to support the roof of the mineThe room and pillar method of mining is generally followed in thin coal seams According to the West ia Coal Association coal recovery in room and pillar mining ranges between 40 60 of
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Mining low coal seams less than 1 m with the room and pillar mining method implies the excavation of part of the roof or floor to maintain adequate entry height for equipment and compliance with labor regulations with respect to ergonomic issu The direct consequence of this is an increase in coal contamination and the increased cost of Room and pillar is an underground mining method that has applications to a wide variety of hard rock deposits worldwide It is commonly classified as an open stoping method meaning that development involves mining out underground cavities while leaving the
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underground miners Traditional strength based pillar design methods applicable to coal or hard rock mines use a factor of safety defined as pillar strength divided by pillar stress Factor of stability defined as local mine stiffness divided by post failure pillar stiffness may offer a way to design room and pillar mines and eliminate collapsRoom and pillar mining proceed inner away from the entrance of the mine When the coal seam goes out or the mine s property line is reached retreat mining is a method that recovers the supporting coal pillars working from the back of the mine through the entrance thus the word retreat Room and pillar mining leaves at the rear
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Coal Mining Methods Underground Mining Longwall Room and Pillar Mining Longwall mining and room and pillar mining are the two basic methods of mining coal underground with room and pillar being the traditional method in the United Stat Both methods are well suited to extracting the relatively flat coalbeds or coal seams typical ofOct 19 32 Abstract Underground mining using the room and pillar method leaves pillars to support the overlying strata When longwall mining is used to extract a lower coal seam beneath the room and pillar mine the bending of the interburden strata can induce pillar failure and roof caving
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May 31 32 In a coal mine the bord is actually a room or a space not a badly spelled plank What is bord and pillar mining Two main methods of extraction are used for underground coal mines Oct 22 32 Room and Pillar Mining Method 1 Hassan Z Harraz hharraz yahoo This material is intended for use in lectures presentations and as handouts to students and is provided in Power point format so as to allow customization for the individual needs of course instructors
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FIGURE F 1 Schematic of a room and pillar coal mine section SOURCE Arch Coal Inc FIGURE F 2 Details of the longwall face SOURCE EIA There are several variations of each method However ever since the introduction of continuous miners in the late s room and pillar continuous mining has been gaining ground over conventional room and pillar miningunderground miners Traditional strength based pillar design methods applicable to coal or hard rock mines use a factor of safety defined as pillar strength divided by pillar stress Factor of stability defined as local mine stiffness divided by post failure pillar stiffness may offer a way to design room and pillar mines and eliminate collaps
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Underground Mining Methods Room and Pillar method Step mining Post pillar mining Configuring the R P method in coal Main design parameters of R P in coal dimensions of the galleries The highest coal recovery is normally achieved when retreat mining is combined with room and pillar mining This method is often referred to as room and pillar with retreat mining Retreat mining is a systematic removal of coal support pillars once a mining section has been developed using standard room and pillar mining
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The room and pillar system is used in mining coal iron and base metals ores particularly when found as manto or blanket deposits stone and aggregates talc soda ash and potash The key to successful room and pillar mining is in the selection of the optimum pillar sizeRoom And Pillar Method Coal Mine Room and pillar method coal minecales back roomAnd pillar business miningoom and pillar is stillUsed in underground coal mining is moving away fromRoom and pillar mining a business thatnderground miningFact sheetr roomandpillar miningTechnologyongwall mining in room and pillar mining theTunnels where the coal is removed
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The highest coal recovery is normally achieved when retreat mining is combined with room and pillar mining This method is often referred to as room and pillar with retreat mining Retreat mining is a systematic removal of coal support pillars once a mining section has been developed using standard room and pillar miningCOAL MINING METHODS Underground coal mining methods are classified according to the method of ground control an excellent description of all methods is provided in Samuel M Cassidy Ed Elements of Practical Coal Mining New York American Institute of Mining Engineers as either room and pillar or longwall shortwall is considered a
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