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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 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 manpower. The room ... [...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 Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ... 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 or flashes at the surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology), crust result from the action of Plate tectonics, plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction, subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the Plane (geometry), plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geological maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleveland, Ohio
Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County, Ohio, Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the Canada–United States border, Canada–U.S. maritime border and approximately west of the Ohio-Pennsylvania state border. Cleveland is the most populous city on Lake Erie, the list of cities in Ohio, second-most populous city in Ohio, and the List of United States cities by population, 53rd-most populous city in the U.S. with a population of 372,624 in 2020. The city anchors the Greater Cleveland, Cleveland metropolitan area, the Metropolitan statistical area, 33rd-largest in the U.S. at 2.18 million residents, as well as the larger Cleveland–Akron, Ohio, Akron–Canton, Ohio, Canton combined statistical area with 3.63 million residents. Cleveland was founded in 1796 near the mouth of the Cuyahoga River as part of the Connecticut Western Reserve in modern-day Northeast Ohio by General Moses Clea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Erie
Lake Erie ( ) 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 also has the shortest average water lake retention time, residence time. At its deepest point, Lake Erie is deep, making it the only Great Lake whose deepest point is above sea level. Located on the Canada–United States border, International Boundary between Canada and the United States, Lake Erie's northern shore is the Provinces and territories of Canada, Canadian province of Ontario, specifically the Ontario Peninsula, with the U.S. states of Michigan, Ohio, Pennsylvania, and New York (state), 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 Chicago metropoli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Huron
Lake Huron ( ) is one of the five Great Lakes of North America. 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 indigenous people they knew as Wyandot people, Huron (Wyandot) inhabiting the region. Hydrology, Hydrologically, Lake Huron comprises the eastern portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Straits of Mackinac. Combined, Lake Michigan–Huron is the largest fresh water, freshwater lake by area in the world. The Huronian glaciation was named from evidence collected from the Lake Huron region. The northern parts of the lake include the North Channel (Ontario), North Channel and Georgian Bay. Saginaw Bay is located in the southwest corner of the lake. The main inlet is the St. Marys River (Michigan–Ontario), St. Marys River from Lake Sup ... [...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 2021 Census, the population is 7,881 in a land area of 8.54 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. The earliest found salt mine was in Hallstatt, Austria where salt was mined, starting in 5000BC. As salt is a necessity of life, pre-industrial governments were usually keen to exercise stringent control over its production, often through direct ownership of ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Gypsum
USG Corporation, also known as United States Gypsum Corporation, is an American company which manufactures construction materials, most notably drywall and joint compound. The company is the largest distributor of wallboard in the United States and the largest manufacturer of gypsum products in North America. It is also a major consumer of synthetic gypsum, a byproduct of flue-gas desulfurization. Its corporate offices are located at 550 West Adams Street in Chicago, Illinois. USG's most significant brands include Sheetrock Brand Gypsum Panels, Securock Brand Glass-Mat Sheathing and Sheetrock Brand All Purpose Joint Compound. In December 2013, Warren Buffett's Berkshire Hathaway became the largest shareholder in the company (holding roughly 30%) when it converted USG convertible notes it had acquired in 2008 to common stock. In June 2018, USG entered into an agreement to be purchased by the privately-held building materials company Knauf. It operates as an independent subsid ... [...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. Advantages of surface mining include lower cost and greater safety compared to underground mini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mine Safety And Health Administration
The Mine Safety and Health Administration (MSHA) () is a small 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, 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
