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Retreat Mining
Retreat mining is the removal of pillars in the underground mining technique known as room and pillar mining. In the first phase of room and pillar mining, tunnels are advanced into the coal or ore body in a rectangular pattern resembling city streets. Pillars are left between tunnels to support the weight of the overburden. The first phase is known as "mining on the advance," from the entrance toward the further reaches of the reserve. In the second phase, once advance mining has been completed, pillars are removed "on the retreat." Removing or "pulling" pillars begins far from the entrance and proceeds toward the entrance. As the pillars are removed, the mine collapses because nothing remains to support the roof and overburden. Removing pillars causes stresses within the mine to shift and must be planned and executed carefully to reduce danger to miners and control the amount of stress exerted on remaining pillars and the mine floor. Tunnels only make up about 15% of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barrier Panel
A barrier or barricade is a physical structure which blocks or impedes something. Barrier may also refer to: Places * Barrier, Kentucky, a community in the United States * Barrier, Voerendaal, a place in the municipality of Voerendaal, Netherlands * Barrier Bay, an open bay in Antarctica * Barrier Canyon, the former name of Horseshoe Canyon (Utah) * Barrier Lake, Alberta, Canada * Barrier Mountain, the former name of Mount Baldy (Alberta) * Barrier Ranges, a mountain range in New South Wales, Australia * Division of Barrier, a former Australian Electoral Division in New South Wales * The Barrier, a lava dam in British Columbia, Canada * The Barrier (Kenya), an active shield volcano in Kenya * The Barrier, a common synonym for the city of Broken Hill, New South Wales * The Barrier, an early name for the Ross Ice Shelf, Antarctica In arts and entertainment Film * The Barrier (1917 film), ''The Barrier'' (1917 film), a lost 1917 American silent drama film * The Barrier (1926 film), ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mining
Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic viability of investing in the equipment, labor, and energy required to extract, refine and transport the materials found at the mine to manufacturers who can use the material. Ores recovered by mining include metals, coal, oil shale, gemstones, limestone, chalk, dimension stone, rock salt, potash, gravel, and clay. Mining is required to obtain most materials that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even water. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Room And Pillar
Room and pillar or pillar and stall is a variant of breast stoping. It is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars. To do this, "rooms" of ore are dug out while "pillars" of untouched material are left to support the roof overburden. Calculating the size, shape, and position of pillars is a complicated procedure, and is an area of active research. The technique is usually used for relatively flat-lying deposits, such as those that follow a particular stratum. Room and pillar mining can be advantageous because it reduces the risk of surface subsidence compared to other underground mining techniques. It is also advantageous because it can be mechanized, and is relatively simple. However, because significant portions of ore may have to be left behind, recovery and profits can be low. Room and pillar mining was one of the earliest methods used, although with significantly more man-power. The roo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mine Safety And Health Administration
The Mine Safety and Health Administration (MSHA) () is a large agency of the United States Department of Labor which administers the provisions of the Federal Mine Safety and Health Act of 1977 (Mine Act) to enforce compliance with mandatory safety and health standards as a means to eliminate fatal accidents, to reduce the frequency and severity of nonfatal accidents, to minimize health hazards, and to promote improved safety and health conditions in the nation's mines. MSHA carries out the mandates of the Mine Act at all mining and mineral processing operations in the United States, regardless of size, number of employees, commodity mined, or method of extraction. David Zatezalo was sworn in as Assistant Secretary of Labor for Mine Safety and Health, and head of MSHA, on November 30, 2017. He served until January 20, 2021. Jeannette Galanais served as Acting Assistant Secretary by President Joe Biden on February 1, 2021 until Christopher Williamson took office on April 11, 2022. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crandall Canyon Mine
The Crandall Canyon Mine, formerly Genwal Mine, was an underground bituminous coal mine in northwestern Emery County, Utah. The mine made headline news when six miners were trapped by a collapse in August 2007. Ten days later, three rescue workers were killed by a subsequent collapse. The six miners were later declared dead and their bodies were never recovered. Location and geography The Crandall Canyon Mine is located at (39.460000°, -111.167639°) with its entrance at an elevation of 7,835 feet (2,388m). The mine is located in Emery County, Utah, in the Wasatch plateau coal field. The mine is located about 140 miles (225 km) south of Salt Lake City, 34 miles (55 km) southeast of Fairview, and about 15 miles (24 km) west north-west of Huntington. The mine is located in Crandall Canyon about 1.25 miles (2 km) west of its junction with the main highway road, State Route 31, which runs through Huntington Canyon. The Manti-La Sal National Forest surrounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Washington Post
''The Washington Post'' (also known as the ''Post'' and, informally, ''WaPo'') is an American daily newspaper published in Washington, D.C. It is the most widely circulated newspaper within the Washington metropolitan area and has a large national audience. Daily broadsheet editions are printed for D.C., Maryland, and Virginia. The ''Post'' was founded in 1877. In its early years, it went through several owners and struggled both financially and editorially. Financier Eugene Meyer (financier), Eugene Meyer purchased it out of bankruptcy in 1933 and revived its health and reputation, work continued by his successors Katharine Graham, Katharine and Phil Graham (Meyer's daughter and son-in-law), who bought out several rival publications. The ''Post'' 1971 printing of the Pentagon Papers helped spur opposition to the Vietnam War. Subsequently, in the best-known episode in the newspaper's history, reporters Bob Woodward and Carl Bernstein led the American press's investigation into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associated Press
The Associated Press (AP) is an American non-profit news agency headquartered in New York City. Founded in 1846, it operates as a cooperative, unincorporated association. It produces news reports that are distributed to its members, U.S. newspapers and broadcasters. The AP has earned 56 Pulitzer Prizes, including 34 for photography, since the award was established in 1917. It is also known for publishing the widely used '' AP Stylebook''. By 2016, news collected by the AP was published and republished by more than 1,300 newspapers and broadcasters, English, Spanish, and Arabic. The AP operates 248 news bureaus in 99 countries. It also operates the AP Radio Network, which provides newscasts twice hourly for broadcast and satellite radio and television stations. Many newspapers and broadcasters outside the United States are AP subscribers, paying a fee to use AP material without being contributing members of the cooperative. As part of their cooperative agreement with the AP, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longwall Mining
Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically thick). The longwall panel (the block of coal that is being mined) is typically long (but can be upto long) and wide. History The basic idea of longwall mining was developed in England in the late 17th 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 Shropshire method of mining. While the technology has changed considerably, the basic idea remains the same, to remove essentially all of the coal from a broad coal face and allow the roof and overlying rock to collapse into the void behind, while maintaining a safe working space along the face for the miners. Starting around 1900, mechanization was applied to this method. By 1940, some referred to longwall mining as "the conveyor method" of mining, after the most prominent pie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountaintop Removal Mining
Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining at the summit or summit ridge of a mountain. Coal seams are extracted from a mountain by removing the land, or overburden, above the seams. This process is considered to be safer compared to underground mining because the coal seams are accessed from above instead of underground. In the United States, this method of coal mining is conducted in the Appalachian Mountains in the eastern United States. Explosives are used to remove up to 400 vertical feet (120 m) of mountain to expose underlying coal seams. Excess rock and soil is dumped into nearby valleys, in what are called "holler fills" ("hollow fills") or "valley fills".U.S. Environmental Protection Agency, "Mountaintop Mining/Valley Fills in Appalachia: Final Programmatic Environmental Impact Statement," issued 2005 June 25, available ahttp://www.epa.gov/region03/mtntop/index.htm(accessed 2006 August 20). The practice of MTM h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Fracturing
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. As of 2012, 2.5 million "frac jobs" had been performed worldwide on oil and gas wells, over one million of those within the U.S. Such treatment is generally necessary to achieve adequate flow rates in shale gas, tight ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directional Drilling
Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal directional drilling - HDD), and surface in seam (SIS), which horizontally intersects a vertical bore target to extract coal bed methane. History Many prerequisites enabled this suite of technologies to become productive. Probably, the first requirement was the realization that oil wells, or water wells, do not necessarily need to be vertical. This realization was quite slow, and did not really grasp the attention of the oil industry until the late 1920s when there were several lawsuits alleging that wells drilled from a rig on one property had crossed the boundary and were penetrating a reservoir on an adjacent property. Initially, proxy evidence such as production changes in other wells was accepted, but such cases fueled the development ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
