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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] |
Stoping
Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to collapse into the stope, although in most cases artificial support is also provided. The earliest forms of stoping were conducted with hand tools or by fire-setting; later gunpowder was introduced. From the 19th century onward, various other explosives, power-tools, and machines came into use. As mining progresses the stope is often backfilled with tailings, or when needed for strength, a mixture of tailings and cement. In old mines, stopes frequently collapse at a later time, leaving craters at the surface. They are an unexpected danger when records of underground mining have been lost with the passage of time. Stoping is considered "productive work", and is contrasted with "deadwork", the work required merely to access the mineral deposit, such as sinking shafts and win ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Compaction
In geotechnical engineering, soil compaction is the process in which stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water (or other liquid) being displaced from between the soil grains, then consolidation, not compaction, has occurred. Normally, compaction is the result of heavy machinery compressing the soil, but it can also occur due to the passage of, for example, animal feet. In soil science and agronomy, soil compaction is usually a combination of both engineering compaction and consolidation, so may occur due to a lack of water in the soil, the applied stress being internal suction due to water evaporation as well as due to passage of animal feet. Affected soils become less able to absorb rainfall, thus increasing runoff and erosion. Plants have difficulty in compacted soil because the mineral grains are pressed together, leaving little space for air and wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coal Mining In The United States
Coal mining is an industry in transition in the United States. Production in 2019 was down 40% from the peak production of in 2008. Employment of 43,000 coal miners is down from a peak of 883,000 in 1923. Generation of electricity is the largest user of coal, being used to produce 50% of electric power in 2005 and 27% in 2018. The U.S. is a net exporter of coal. U.S. coal exports, for which Europe is the largest customer, peaked in 2012. In 2015, the U.S. exported 7.0 percent of mined coal. According to the Energy Information Administration, U.S. Energy Information Administration (EIA), in 2015, Wyoming, West Virginia, Kentucky, Illinois, and Pennsylvania produced about , representing 71% of total coal production in the United States. In 2015, four publicly traded US coal companies filed for Chapter 11, Title 11, United States Code, Chapter 11 bankruptcy protection, including Patriot Coal, Patriot Coal Corporation, Walter Energy, and the fourth-largest Alpha Natural Reso ... [...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] |
Cleveland, Ohio
Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. maritime border with Canada, northeast of Cincinnati, northeast of Columbus, and approximately west of Pennsylvania. The largest city on Lake Erie and one of the major cities of the Great Lakes region, Cleveland ranks as the 54th-largest city in the U.S. with a 2020 population of 372,624. The city anchors both the Greater Cleveland metropolitan statistical area (MSA) and the larger Cleveland–Akron–Canton combined statistical area (CSA). The CSA is the most populous in Ohio and the 17th largest in the country, with a population of 3.63 million in 2020, while the MSA ranks as 34th largest at 2.09 million. Cleveland was founded in 1796 near the mouth of the Cuyahoga River by General Moses Cleaveland, after whom the city was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Erie
Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. At its deepest point Lake Erie is deep. Situated on the International Boundary between Canada and the United States, Lake Erie's northern shore is the Canadian province of Ontario, specifically the Ontario Peninsula, with the U.S. states of Michigan, Ohio, Pennsylvania, and New York on its western, southern, and eastern shores. These jurisdictions divide the surface area of the lake with water boundaries. The largest city on the lake is Cleveland, anchoring the third largest U.S. metro area in the Great Lakes region, after Greater Chicago and Metro Detroit. Other major cities along the lake shore include Buffalo, New York; Erie, Pennsylvania; and Toledo, Ohio. Situated below Lake ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Huron
Lake Huron ( ) is one of the five Great Lakes of North America. Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Straits of Mackinac. It is shared on the north and east by the Canadian province of Ontario and on the south and west by the U.S. state of Michigan. The name of the lake is derived from early French explorers who named it for the Huron people inhabiting the region. The Huronian glaciation was named from evidence collected from Lake Huron region. The northern parts of the lake include the North Channel and Georgian Bay. Saginaw Bay is located in the southwest corner of the lake. The main inlet is the St. Marys River, and the main outlet is the St. Clair River. Geography By surface area, Lake Huron is the second-largest of the Great Lakes, with a surface area of —of which lies in Michigan; and lies in Ontario—making it the third-largest fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goderich, Ontario
Goderich ( or ) is a town in the Canadian province of Ontario and is the county seat of Huron County. The town was founded by John Galt and William "Tiger" Dunlop of the Canada Company in 1827. First laid out in 1828, the town is named after Frederick John Robinson, 1st Viscount Goderich, who was prime minister of the United Kingdom at the time. It was incorporated as a town in 1850. As of the Canada 2016 Census, the population is 7,628 in a land area of 8.64 square kilometres. Located on the eastern shore of Lake Huron at the mouth of the Maitland River, Goderich faces the lake to the west and is notable for its sunsets. Some claim that Queen Elizabeth II once commented that Goderich was "the prettiest town in Canada" although no reigning monarch has ever visited Goderich. The town indicates that tourism is among its important industries. It has been named one of Ontario's best small towns by ''Comfort Life'', a website for retirement living in Canada. The town participa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Mine
Salt mining extracts natural salt deposits from underground. The mined salt is usually in the form of halite (commonly known as rock salt), and extracted from evaporite formations. History Before the advent of the modern internal combustion engine and earth-moving equipment, mining salt was one of the most expensive and dangerous of operations because of rapid dehydration caused by constant contact with the salt (both in the mine passages and scattered in the air as salt dust) and of other problems caused by accidental excessive sodium intake. Salt is now plentiful, but until the Industrial Revolution, it was difficult to come by, and salt was often mined by slaves or prisoners. Life expectancy for the miners was low. Ancient China was among the earliest civilizations in the world with cultivation and trade in mined salt. They first discovered natural gas when they excavated rock salt. The Chinese writer, poet, and politician Zhang Hua of the Jin dynasty wrote in his book ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mediapolis, Iowa
Mediapolis is a city in Des Moines County, Iowa, United States. Its population was 1,688 at the time of the 2020 census. It is part of the Burlington, IA– IL Micropolitan Statistical Area. History Mediapolis was founded in the year 1869. It was first a train station for the city of Kossuth, Iowa at a point on the Burlington, Cedar Rapids and Minnesota Railway (later part of the Chicago, Rock Island and Pacific) between Burlington and Wapello. ''Media,'' meaning "middle," was appended to ''polis,'' meaning "village," as Mediapolis is halfway between Wapello and Burlington. From 1875 to the mid 20th century, Mediapolis was a railroad junction where the Burlington and Northwestern Railway to Washington (later a branch of the Chicago, Burlington and Quincy) met the original north-south line. The Rock Island Railroad ceased operation in 1980, leading to the abandonment of the north-south line through Mediapolis. One heavy industry remains two miles southwest of town, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Mining
Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit (the overburden) are removed, in contrast to underground mining, in which the overlying rock is left in place, and the mineral is removed through shafts or tunnels. In North America, where the majority of surface coal mining occurs, this method began to be used in the mid-16th century and is practiced throughout the world in the mining of many different minerals. In North America, surface mining gained popularity throughout the 20th century, and surface mines now produce most of the coal mined in the United States. In most forms of surface mining, heavy equipment, such as earthmovers, first remove the overburden. Next, large machines, such as dragline excavators or bucket-wheel excavators, extract the mineral. The pros of surface mining are that it has a lower financial cost and is a lot safer than under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
