:: wikimiki.org ::
| Longwall |
LongwallLongwall mining is form of underground coal mining which uses a massive machine called a longwall. The longwall equipment consists of a number of hydraulic jacks, called chocks, roof supports or shields, which are placed in a long line up to 400m in length in order to support the roof. An individual chock can extend to a maximum cutting height of up to 5m. The coal is cut by a rotating drum with bits called a shearer that moves along the length of the face in front of the chocks, disintegrating the coal. The coal is then removed from the coal face by a moving chain or AFC (articulated face conveyor) (also called armoured face conveyor) to the main gate. Here it is loaded onto a conveyor belt and transported to the surface.
As the shearer removes the coal, the chocks move forward into the newly created cavity. As mining progresses and the entire longwall progresses through the seam, the cavity behind the longwall, known as the goaf, increases. This goaf collapses under the weight of the overlying strata.
Category:Coal mining
Coal mining
Coal mining is the extraction of coal from the Earth for use during combustion.
Methods of extraction
The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and also the geology and environmental factors of the area being mined.
If the coal seams are near the surface, the coal is extracted by one of two methods. One method, strip mining, exposes the coal by the advancement of an open pit or strip. As the coal is exposed and extracted, the overburden from the still covered coal fills the former pit, and strip progresses. Most open cast mines in the USA extract bituminous coal. In South Wales opencasting for steam coal and anthracite is practised.
However, most coal seams are too deep underground for open cast mining. In deep mining the room and pillar method progresses along the Mammoth coal vein seam, while pillars and timber are left standing to support the coal mine roof. A most dangerous method of operation in deep mining and is dubbed the term robbing the pillars. This term is where miners in this deep mining operation attempt to remove and/or retreat, between the timbers, in order to get coal out of the main coal seam. This allows the roof to cave in. This method of mining is used principally in the United States and contributed to many fatalities in the early history of coal mining.
Another method, longwall mining, is conducted along the seam with the use of self-advancing hydraulic roof supports known as "chocks" or "shields". These supports are placed in a line (up to 400 metres long), known as a "longwall" and as coal is removed from in front of the longwall, the supports are advanced. As the longwall advances, the cavity created behind the longwall known as the "goaf" caves in. Longwall mining is the principle method of underground mining in Australia.
Finally, highwall mining is a form of coal mining in which a continuous miner is controlled remotely from outby, or outside the mine, and is guided along the seam straight back drilling holes in excess of 500 feet. As the coal is sheered off the face of the seam, it falls below to a conveyor belt that transports the coal to the surface. A large amount of capital is required to purchase a highwall mining unit, but the labor costs are low because an operation does not require a full crew.
Other methods of mining include highwall auger mining. These methods are generally applied in an open cast mine, once open cut mining becomes uneconomic.
History
The oldest continuously worked deep-mine in the UK and possibly the world is Tower Colliery at the northern end of the south Wales valleys. This colliery was started in 1805 and at the end of the 20th century it was bought out by its miners rather than allow it to be closed.
The World Championships in coal-carrying take place every Easter Monday, at Ossett in West Yorkshire, UK The race starts from the site of the old Saville & Shaw Cross colliery.
This First commercial coal mines in the United States were built in 1748 in Midlothian, Virginia, near Richmond, Virginia. [http://www.midlothianva.org/history.asp]
In the 1880's, Coal-cutting machines became available (prior to that, coal was mined underground by hand.)
By 1910, surface mining was underway with steam shovels specifically designed for coal mining.
The industry has been subject to sometimes violent labor relations in the U.S. (for example, see Ludlow Massacre); union organizers were sometimes murdered by management. Today, coal mining is highly unionized, and the unions are sometimes militant. Mining communities are often close-knit with a strong sense of community spirit and religious faith.
Dangers to miners
Coal mining, historically, has been a very dangerous activity. Open cut hazards are principally slope failure, underground mining roof collapse and gas explosions. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in the developed world. Improvements in mining methods (i.e. longwall mining), gas drainage, safety-lamps, and ventilation have reduced many of these risks. In lesser developed countries, however, thousands still die in coal mines. China in particular is the world leader in coal mining related deaths, with official estimates of around 6000 fatalities in 2004. Unofficial estimates place the figure much higher, at around 20,000 deaths. China is also the world leader in coal production and consumption.
Chronic lung diseases, such as pneumoconiosis are common to miners, causing a reduced life-expectancy for those in the occupation.
Environmental impacts
Coal mining frequently causes significant adverse environmental impacts. Strip mining typically destroys most environmental value in the land through which it passes. All forms of mining are likely to generate areas where coal is stacked and where the coal has significant sulfur content, such coal heaps generate highly acidic metal rich drainage when exposed to normal rainfall. These liquors can cause severe environmental damage to receiving water-courses. In addition, the waste heaps are subject to slipping, as in the Aberfan disaster which killed 144 people in 1966.
See also
- Acid mine drainage
- Anthracite Coal Region of Pennsylvania
- Bevin Boy
- Black lung disease
- Bootleg mining
- Coal Measures
- Harlan County, USA
- History of coal mining
- Mine fire
- Mining accidents
- Mining in Limburg
- Powder River Basin
- Wilkes-Barre, Pennsylvania
External links
[http://gilbertwesleypurdy.blogspot.com/2005/09/dueling-mythologies.html Dueling Mythologies,] by Gilbert Wesley Purdy. A book review/essay that contains considerable information on coal mining in the early 20th century.
Ernst KaltenbrunnerErnst Kaltenbrunner (4 października 1903 - 16 października 1946) - SS-Obergruppenführer (generał broni), wysoki funkcjonariusz SS, szef Głównego Urzędu Bezpieczeństwa Rzeszy - RSHA w latach 1943 - 1945.
1945
Urodzony w Braunau w Austrii. Uczył się w gimnazjum w Linz oraz na uniwersytecie Graz. W 1926 roku zdobył wykształcenie prawnika, do 1928 roku pracował jako adwokat w Linz i Salzburgu . Od 1930 roku członek austriackiej partii nazistowskiej, od 1935 roku, szef SS w Austrii. Tuż przed zajęciem Austrii przez Niemcy, objął stanowisko sekretarza stanu do spraw bezpieczeństwa w gabinecie Seyss-Inquarta. Po wchłonięciu Austrii do Niemiec, Kaltenbrunner sprawował wysokie kierownicze funkcje w SS, na terenie Austrii przyłączonej do III Rzeszy. Za aktywny udział w Anschlussie, (przyłączeniu Austrii do Niemiec) awansowany przez Adolfa Hitlera do stopnia SS-Brigadeführera (generała brygady). Następnie 11 września 1938 roku, awansował do stopnia SS-Gruppenführera (generał dywizji) oraz został członkiem Reichstagu. W kwietniu 1941 roku mianowany gen. mjr. Policji. 30 stycznia 1943 roku, Ernst Kaltenbrunner zastąpił na stanowisku szefa Głównego Urzędu Bezpieczeństwa Rzeszy (RSHA), Bruno Streckenbacha, następcę Reinharda Heydricha, który zginął w zamachu w Pradze w 1942 roku.
9 grudnia 1944 roku Kaltenbrunner został odznaczony krzyżem rycerskim. Od grudnia 1944 roku doktor Ernst Kaltenbrunner miał w swojej kompetencji bardzo dużą władzę, m.in.: posiadał rangę SS-Obergruppenführera i generała Policji i był szefem Głównego Urzędu Bezpieczeństwa Rzeszy, sprawując w tem sposób kontrolę nad Tajną Policją Polityczną "Gestapo", Służbą bezpieczeństwa Sicherheitsdienst oraz wywiadem zagranicznym SD i wywiadem wojskowym, leżącym jeszcze niedawno w gestii Abwehry. (Do 1944 roku). W 1946 roku Kaltenbrunner został skazany przez Międzynarodowy Trybunał Wojskowy w Norymberdze na karę śmierci i stracony.
Zobacz też
- III Rzesza
- NSDAP
- SA
- SS
- Waffen-SS
- Główny Urząd Bezpieczeństwa Rzeszy
- Gestapo
- Sicherheitsdienst
- Abwehra
- Adolf Hitler
- Heinrich Himmler
- Reinhard Heydrich
- Walter Schellenberg
- Noc długich noży
Kaltenbrunner Ernst
Kaltenbrunner, Ernst
media milan italy hotels Nurkowanie heavy metal prag hotel
|
|
|
| :: RELATED NEWS :: |
Bart Preneel
Bart Preneel is een professor aan de Katholieke Universiteit Leuven, en maakt deel uit van de COSIC-groep (Computer Security and Industrial Cryptography). Hij is één van de uitvinders van de RIPEMD-160-hashfunctie. Samen met Shoji Miyaguchi is hij de ontwerper van de Miyaguchi-Preneel-constructie, een structuur gebruikt in
|
Boloria aquilonaris
De veenbesparelmoervlinder (Boloria aquilonaris) is een dagvlinder uit de familie Nymphalidae, de vossen, parelmoervlinders en weerschijnvlinders. De vlinder heeft een spanwijdte van 34 tot 40 millimeter.
Het verspreidingsgebied van de veenbesparelmoervlinder beslaat Noord- en Centraal-Europa. In Nederland is de vlinder ernstig bedreigd en in België kwetsbaar. De waardplant van de rups is de Turkije zoals de Süper Lig, de Tweede Liga categorie A en de Turkse beker.
De TFF is ook verantwoordelijk voor het Turks voetbalelftal.
|
De Sims 2
De Sims 2 is een strategie-/simulatiespel van Maxis en is het vervolg van het succesvolle spel The Sims. Het verschilt sterk met de vorige versie en er zijn diverse vernieuwingen aangebracht. Het is volledig in 3D en karakters worden, in tegenstelling tot de eerste versie, dit keer ouder en hebben genetische<
|
Tsjechische voetbalbond
De ČMFS of de Českomoravský fotbalový svaz is de Tsjechische voetbalbond. De vertaling van de Tsjechische naam is Boheems-Moravische Voetbalbond. De ČMFS organiseert de competities in Tsjechië zoals de Gambrinus liga, Druhá liga en de Pohár ČMFS.
De ČMFS is ook verantwoordelijk voor het Tsjechisch voetbalel
|
|
Veenbesparelmoervlinder
De veenbesparelmoervlinder (Boloria aquilonaris) is een dagvlinder uit de familie Nymphalidae, de vossen, parelmoervlinders en weerschijnvlinders. De vlinder heeft een spanwijdte van 34 tot 40 millimeter.
Het verspreidingsgebied van de veenbesparelmoervlinder beslaat Noord- en Centraal-Europa. In Nederland is de vlinder ernstig bedreigd en in België kwetsbaar. De waardplant van de rups is de Erasmus van Rotterdam) was de eerste metrolijn van Rotterdam. De lijn was tevens de kortste metrolijn ter wereld: 5,9 kilometer tussen het Centraal Station en het winkelcentrum Zuidplein op de linker Maasoever. Met de bouw van de lijn, die ruim zeven jaar duurde, was een bedrag van 170
|
|
