The development and use of very heavy duty face conveyors a. Impacts of longwall mining on surface water and groundwater, southern coalfield nsw ewater crc 1. Since it is envisaged that longwall mining will require time to become established in india, bordandpillar methods will continue to be dominant in the foreseeable future. In the longwall system the ore body is divided into rectangular panels or blocks. Of this, 51% of the production is produced by longwall mines eia, 2006. According to hartman and mutmansky 2002, longwall mining is an exploitation method used in flatlying and tabular deposits, where a long face is established to extract the mineral. Longwall mining is a highly mechaniz ed underground mining sys tem for mining coal. This book presents the latest mining principles and techniques in use today. In retreat mining, the longwall face is installed and as mining continues into the panel the entries are allowed to collapse behind the face line to form part of the gob. Introduction to longwall mining and subsidence mine subsidence. It occurs when underground voids or cavities collapse, or when soil or geological formations including coal seams, sandstone and other sedimentary strata compress due to changes in moisture content and pressure within the ground. Definition of longwall mining a high extraction method of mining along the face of a predefined block of coal, referred to as a panel, while allowing the immediate roof to collapse upon advancement panel configuration panels generally range in size from 500 to 1,000 feet. With the longwall method as much as 7075% of the coal in.
Analysis and optimization of entry stability in underground. At present, production by longwall mining accounts for a minor amount of total underground mining production with the majority coming from bordandpillar methods. 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. In each panel two or more parallel drifts for ventilation and ore transport are driven along the opposite long sides to provide access, and at the end of the. Furthermore, the slices are as much as three metres thick and are taken by a continuous miner. The high productivity being achieved by longwall mining demonstrates its potential for being a substantial segment of underground coal production. In coal longwall mining, large blocks of coal seam about 300 m wide and 2 to. The essential geomechanical features of longwall and caving methods of mining were outlined in chapter 12. Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice typically 0. In each panel two or more parallel drifts for ventilation and ore transport are driven along the opposite.
For these reasons, much of this chapter compares longwall mining with the dominant underground mining technology in the westroomandpillar mining with continuous miners. Average longwall production as reported by mine operators. The elements of the longwall method of coal mining are illustrated in figure. In the method of secondary extraction known as longwall mining a relatively long mining face typically in the range 100 to 300m but may be longer is created by driving a roadway at right angles between two roadways that form the sides of the longwall block, with one rib of this new roadway forming the longwall face. Apr 18, 2020 longwall mining is a highly productive underground coal mining technique. Pdf two new barrier pillar design methods for longwall. One of the most sophisticated and automated ways to mine coal is through longwall mining. The continued growth of longwall mining without appropriate multipleseam planning may increase the cost and risk of mining. As with longwall mining in hard rock, the primary objective of mining design is.
Caving underground mining methods longwall, sublevel caving. The two industries ranked together as the primary or basic industries of early civilization. This report highlights the coal mining methods, their significances, issues of concern and the stages of using coal after mining. Longwall mining machines consist of multiple coal shearers mounted on a series of selfadvancing hydraulic ceiling supports.
Both methods are well suited to extracting the relatively flat coalbeds or coal seams typical of the united states. Second, the abutment loads applied to longwall pillars are significantly greater and more complex than those assumed by traditional pillar design methods. Finally, a brief prospect for coal exploration and mining. In the longwall mining method, mine dev elopment is carried out in such a manner tha t large blocks of coal, usually 100 to 300 metres wide and 1,000 to 3,000 metres long, are available for com plete. Pillar design methods for longwall mining book, 1990. It set of longwall mining equipment consists of a coal shear er mounted on convey or operating. Reflecting the international and diverse nature of the industry, a series of mining case studies is presented covering the commodity range from iron ore to diamonds extracted by operations located in all corners of the world. Longwall mining overview introduction underground coal.
In turkey, mining of thick coal seams is often carried out employing longwall methods. This is due principally to the gradual sinking of the roof in longwall mining where the same gradual movement generally extends through the overlying rocks toward the surface. Two new barrier pillar design methods for longwall mining. Longwall and caving methods are distinguished from other mining methods by the fact that the nearfield rock undergoes large displacements so that mined voids become selffilling. Adapted to the mining challenges faced by our customers today, cat customized systems for longwall mining include hydraulic roof supports, highhorsepower shearers, automated plow systems and armored face conveyors with intelligent drive technology controlled. Improved gpsbased 3d surveying methods, plus the expansion of longwall monitoring since the mid1980s, have highlighted a number of other subsidencerelated ground phenomena. Underground mining methods and technology, volume 1 1st edition. Dilip kumar, deepak kumar, in management of coking coal resources, 2016. Longwall associates is an international oem supplier of longwall conveyor systems. Pdf coal mining methods underground mining longwall. Approximately 45 longwalls are in operation at a given time.
Coal exploration and mining encyclopedia of life support. However, labor is costly, and manual mining tech niques are inefficient. Greater use of longwall mining, replacing bordandpillar mining, will improve resource recovery. Apr 12, 2016 this video provides a basic description of the longwall mining method for extracting coal underground. In the shortwall mining method, the layout is similar to the longwall method except that the block of coal is not more than 100 metres wide. Introduction to longwall mining and subsidence ver2. Other articles where shortwall method is discussed. Optimization of the mine design factors is arguably the primary means for controlling interactions between operations. The longwall face is indicated by the number 8 in the diagram. Longwall mining a set of longwall mining equipment consists of a coal shearer mounted on conveyor operating underneath a series of selfadvancing hydraulic roof supports. In advance mining, the longwall face is set up a short distance from the main development tunnels or headings. Underground mining methods presents the latest principles and techniques in use today. Although widely used in other countries, longwall mining.
Longwall mining is also scheduled to be installed at other large underground operations in the west. Underground mining methods and technology, volume 1 1st. Definition of longwall mining a high extraction method of mining along the face of a predefined block of coal, referred to as a panel, while allowing the immediate roof to collapse upon advancement panel configuration panels generally range in size from 500 to 1,000 feet in width and lengths exceeding two miles. The longwall panel the block of coal that is being mined is typically 34 km 1. Underground coal mining accounts for 33% of the coal production in the united states. Longwall mining and roomandpillar mining are the two basic methods of mining coal underground, with roomandpillar being the traditional method in the united states. Effective longwall pillar design requires some knowledge of abutment loads during all phases of longwall mining, from development all the way into the tailgate. Firstly, two main methodsstrip mining and openpit miningof surface mining are discussed. All more mine designs were developed for 85,000 tons per day minimum production or enough feedstock for 50,000 barrel per day surface processing plant. In case of thick seams, sublevel caving, hydraulic mining. In underground mining, room and pillar, shortwall, and longwall mining methods are introduced. According to available records, ongwall mining started l in illinois shortly after 1856 in lasalle.
A brief comparison of longwall methods used at mining of. The shearer machine cuts coal from the seam and on to the face conveyor to be transported to the surface. Longwall mines produce more than 30 pct of all underground coal, up from 5 pct just 15 years ago. Figure f1 schematic of a roomandpillar coal mine section. Caving underground mining methods longwall, sublevel.
Design and development of longwall shearers for overseas application k. Monitoring and management of subsidence induced by. Monitoring and management of subsidence induced by longwall coal mining activity is licensed by the commonwealth of australia for use under a creative commons by attribution 3. Longwall mining is a highly productive underground coal mining technique. Most aspects of alternative cutting methods and cutting procedures have been referred to in the longwall section of the fundamentals of coal mining module of this web site and little can be added here. This video provides a basic description of the longwall mining method for extracting coal underground. Mining methods for underground mining of oilshale m. The second section describes underground mining equipment, with particular focus on excavation machinery such as boomheaders, coal cutters, continuous miners and shearers. Effective longwall pillar design requires some knowledge of abutment loads during all phases of longwall. Longwall mining machines are about 800 feet 240 meters in width and 5 to 10 feet 1. Adapted to the mining challenges faced by our customers today, cat customized systems for longwall mining include hydraulic roof supports, highhorsepower shearers, automated plow systems and armored face conveyors with intelligent drive technology controlled and supported by advanced longwall automation. In any underground mining activity, the in situ vertical and horizontal stresses that exist in the rock are disrupted and redistributed by the mining process.
Advances in longwall mining method have made this system more economically attractive because of its efficiency and production potential. Room and pillar and long wall mining ruben pillar is a mining method involving the extraction of coal that forms a series of rooms while leaving pillars or columns of coal to help support the mind roof the rooms are generally 20 to 30 feet wide and the remaining pillars are 20 to 90 feet wide as production advances a gridlike pattern. Longwall mines produce more than 30 pct of all underground. Longwall mining machines are typically 150250 metres in width and 1. It may be said that in general the surface effects of longwall mining are more uniform than those resulting from roomandpillar and panel workings. Impacts of longwall mining on surface water and groundwater. It includes an explanation of the different productskey components of a longwall mining.
Subsidence produced by longwall coal mining the mechanical aspects of the subsidence pro cess in flatlying coal bearing rocks mined by longwall methods are reasonably well known, compared to roomandpillar mining, and are documented abundantly in the literature. Underground mining methods engineering fundamentals and. The actual method of mining may be longwall, bord and pillar or room and pillar though the method that has been normally adopted has been longwall advancing or longwall retreating as the countries that have first tried horizon mining and later developed it, were accustomed to longwall methods of mining. The longwall mining method extracts ore along a straight front having a large.
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