Coal open pit mining

By | 04.01.2018
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Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. Basics of an open pit mine. Photo of Magma Copper's Open Pit Mine In Arizona. Fig. 1, Open pit mines can be used in coal mining. Coal Mining Technologies. Coal Strip and auger mining are the two most common surface methods of extracting coal in the United States. Open-pit mining is.
Open-pit mining: Open-pit mining,, surface mining (q.v.) to obtain minerals other than. When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast, open pit, mountaintop removal or strip. Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. Basics of an open pit mine. Photo of Magma Copper's Open Pit Mine In Arizona. Fig. 1, Open pit mines can be used in coal mining. Coal Mining Technologies. Coal Strip and auger mining are the two most common surface methods of extracting coal in the United States. Open-pit mining is.

"Coalmine" redirects here. For the Sara Evans song, see Coalmine (song).

"Coal miner" redirects here. For the John J. Szaton statue, see Coal Miner coal open pit mining mining is the process of extractingcoal from the ground. Coal is valued for its energy content, and, since the 1880s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United Kingdom and South Africa, a coal mine and its structures are a colliery, a coal mine a pit, and the above-ground structures the pit head. In Australia, "colliery" generally refers to an underground coal mine. Bitcoin mining best share the United States, "colliery" has been used to describe a coal mine operation but nowadays the word is not commonly used.

Coal mining has had many developments over the recent years, from the early days of men tunnelling, digging and manually extracting the coal on carts, to large open cut and long wall mines. Mining at this scale requires the use of draglines, trucks, conveyors, hydraulic jacks and shearers.

History[edit]

Main article: History of coal mining

Small-scale mining of surface deposits dates back thousands of years. For example, in Roman Britain, the Romans were exploiting most of the major coalfields by the late 2nd century AD.[1]

The Industrial Revolution, which began in Britain in the 18th century and later spread to continental Europe and North America, was based on the availability of coal to power steam engines. International trade expanded rapidly when coal-fed steam engines were built for the railways and steamships.

Until the late nineteenth century coal was mined underground using a pick and shovel, and children were often employed underground in dangerous conditions.[2] Coal-cutting machines were introduced in the 1880s. By 1912, surface mining was conducted with steam shovels designed for coal mining.

[edit]

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and the geology and environmental factors. Coal mining processes are differentiated by whether they operate on the surface or underground. Many coals extracted from both surface and underground mines require washing in a coal preparation plant. Technical and economic feasibility are evaluated based on the following: regional geological conditions; overburden characteristics; coal seam continuity, thickness, structure, coal open pit mining, quality, and depth; strength of materials coal open pit mining and below the seam for roof and floor conditions; topography (especially altitude and slope); climate; land ownership as it affects the availability of land for mining and access; surface drainage patterns; ground water conditions; availability of labor and screensaver mining coal purchaser requirements in terms of tonnage, quality, and destination; and capital investment requirements.[3]

Surface mining and deep underground mining are the two basic methods of mining. The choice of mining method depends primarily on depth, density, overburden and thickness of the coal seam; seams relatively close to the surface, at depths less than approximately 180 ft (55 m), are usually surface mined.

Coal that occurs at depths of 180 to 300 ft (55 to 90 m) are usually deep mined, but in some cases surface mining techniques can be used. For example, some western U.S. coal that occur at depths in excess of 200 ft (60 m) are mined by the open coal open pit mining methods, due to thickness of the seam 60–90 feet (20–25 metres). Coals occurring below 300 ft (90 m) are usually deep mined.[4] However, there are open pit mining operations working on coal seams up to 1,000–1,500 feet (300–460 metres) below ground level, for instance Tagebau Hambach in Germany.

Surface mining[edit]

When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast, open pit, mountaintop removal or strip) mining methods. Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. This equipment can include the following: Draglines which operate by removing the overburden, power shovels, large trucks in which transport overburden and coal, bucket wheel excavators, and conveyors. In this mining method, coal open pit mining, explosives are first used in order to break through hd 4550 mining surface or overburden, of the mining area. The overburden is then removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled, fractured and thoroughly mined in strips. The coal is then loaded onto large trucks or conveyors for transport to either the coal preparation plant or directly to where it will be used.[5]

Most open cast mines in the United States extract bituminous coal. In Canada (BC), Australia and South Africa, open cast mining is used for both thermal and metallurgical coals. In New South Wales open casting for steam coal and anthracite is practiced, coal open pit mining. Surface mining accounts for around 80 percent of production in Australia, while in the US it is used for about 67 percent of production. Globally, about 40 percent of coal production involves surface mining.[5]

Strip mining[edit]

Strip mining exposes coal by removing earth above each coal seam. This earth is referred to as overburden and is removed in long strips. The overburden from the first strip is deposited in an area outside the planned mining area and referred to as out-of-pit dumping. Overburden from subsequent strips are deposited in the void left from mining the coal and overburden from the previous strip. This is referred to as in-pit dumping.

It is often necessary to fragment the overburden by use of explosives. This is accomplished by drilling holes into the overburden, filling the holes with explosives, and detonating the explosive. The overburden is then removed, using large earth-moving equipment, such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the previously mined (and now empty) strip. When all the overburden is removed, the underlying coal seam will be exposed (a 'block' of coal). This block of coal may be drilled and blasted (if hard) or otherwise loaded onto trucks or conveyors for transport to the coal preparation (or wash) plant. Once this strip is empty of coal, the process is repeated with a new strip being created next to it. This method is most suitable for areas with flat terrain.

Equipment to be used depends on geological conditions. For example, to remove overburden that is loose or unconsolidated, a bucket wheel excavator might be the most productive. The life of some area mines may be more than 50 years.[6]

Contour mining[edit]

The contour mining method consists of removing overburden from the seam in a pattern following the contours along a ridge or around the hillside. This method is most commonly used in areas with rolling to steep terrain. It was once common to deposit the spoil on the downslope side of the bench thus created, but this method of spoil disposal consumed much additional land and created severe landslide and erosion problems. To alleviate these problems, a variety of methods were devised to use freshly cut overburden to refill mined-out areas. These haul-back or lateral movement methods generally consist of an initial cut with the spoil deposited downslope or at some other site and spoil from the second cut refilling the first. A ridge of undisturbed natural material 15 to 20 ft (5 to 6 m) wide is often intentionally left at the outer edge of the mined area. This coal open pit mining adds stability to the reclaimed slope by preventing spoil from slumping or sliding downhill

The limitations of contour strip mining are both economic and technical. When the operation reaches a predetermined stripping ratio (tons of overburden/tons of coal), it is not profitable to continue. Depending on the equipment available, it may not be technically feasible to exceed a certain height of highwall. At this point, it is possible to produce more coal with the augering method in which spiral drills bore tunnels into a highwall laterally from the bench to extract coal without removing the overburden.

Mountaintop removal mining[edit]

Main article: Mountaintop removal

Mountaintop coal mining is a surface mining practice involving removal of mountaintops to expose coal seams, and disposing of associated mining overburden in adjacent "valley fills." Valley fills occur in steep terrain where there are limited disposal alternatives.

Mountaintop removal combines area and contour strip mining methods. In areas with rolling or steep terrain with a coal seam occurring near the top of a ridge or hill, the entire top is removed in a series of parallel cuts. Overburden is deposited in nearby valleys and hollows. This method usually leaves ridge and hill tops as flattened plateaus.[4] The process is highly controversial for the drastic changes in topography, the practice of creating head-of-hollow-fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.[7][8]

Spoil is placed at the head of a narrow, steep-sided valley or hollow. In preparation for filling this area, vegetation and soil are removed and a rock drain constructed down the middle of the area to be filled, where coal open pit mining natural drainage course previously existed. When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.[6]

Underground mining[edit]

Main article: Underground mining (soft rock)

Most coal seams are too deep underground for opencast mining and require mining for play coal mining, a method that currently accounts for about 60 percent of world coal production.[5] In deep mining, the room and pillar or bord and pillar method progresses along the seam, while pillars coal open pit mining timber are left standing to support the mine roof. Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. Miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible. A work area involved in pillar extraction is called a pillar section.

Modern pillar sections use remote-controlled equipment, including large hydraulic mobile roof-supports, coal open pit mining, which can prevent cave-ins until the miners and their equipment have left a work area. The mobile roof supports are similar to a large dining-room table, but with hydraulic jacks for legs, coal open pit mining. After the large pillars of coal have been mined away, the mobile roof support's legs shorten and it is withdrawn to a safe area. The mine roof typically collapses once the mobile roof supports leave an area.

There are six principal methods of underground mining:

  • Longwall mining accounts for about 50 percent of underground production. Coal open pit mining longwall shearer has a face of 1,000 feet (300 m) or more. It is a sophisticated machine with a rotating drum that moves mechanically back and forth across a wide coal seam. The loosened coal falls onto an armored chain conveyor or pan line that takes the coal to the conveyor belt for removal from the work area. Longwall systems have their own hydraulic roof supports which advance with the machine as mining progresses. As the longwall mining equipment moves forward, overlying rock that is no coal open pit mining supported by coal is allowed to fall behind the operation in a controlled manner. The supports make possible high levels of production and safety. Sensors detect how much coal remains in the seam while robotic controls enhance efficiency. Longwall systems allow a 60-to-100 percent coal recovery rate when surrounding geology allows their use. Inject mining the coal is removed, usually 75 percent of the section, the roof is allowed to collapse in a safe manner.[5]
  • Continuous mining utilizes a Continuous Miner Machine with a large rotating steel drum equipped with tungsten carbide picks that scrape coal from the seam. Operating in a “room and pillar” (also known as coal open pit mining and pillar”) system—where the mine is divided into a series of 20-to-30-foot (5–10 m) “rooms” engineering mineral mining work areas cut into the coal open pit mining can mine as much as 14 tons of coal a minute, more than a non-mechanised mine of the 1920s would produce in an entire day. Continuous miners account for about 45 percent of underground coal production. Conveyors transport the removed coal from the seam. Remote-controlled continuous miners are used to work in a variety of difficult seams and conditions, and robotic versions controlled by computers are becoming increasingly common. Continuous mining is a misnomer, as room and pillar coal mining is very cyclical. In the US, one can generally cut 20 feet (6 meters) (or a bit more with MSHA permission) (12 meters or roughly 40 ft in South Africa before the Continuous Miner goes out and the roof is supported by the Roof Bolter), after which, the face has to be serviced, before it can be advanced again. During servicing, the hd4870 mining miner moves to another face. Some continuous miners can bolt and rock dust the face (two major components of servicing) while cutting coal, while a trained crew may be able to advance ventilation, coal open pit mining, to truly earn the "continuous" label. However, very few mines are able to achieve it. Most continuous mining machines in use in the US lack the ability to bolt and dust. This may partly be because incorporation of bolting makes the machines wider, and therefore, less maneuverable.[citation needed]
  • Room and pillar mining consists of coal deposits that are mined by cutting a network of rooms into the coal seam. Pillars of coal are left behind in order to keep up the roof. The pillars can make up to forty percent of the total coal in the seam, however where there was space to leave head and floor coal there is evidence from recent open cast excavations that 18th-century operators used a variety of room and pillar techniques to remove 92 percent of the in situ coal. However, this can be extracted at a later stage (seeretreat mining).[5]
  • Blast mining or conventional mining, is an older practice that uses explosives such as dynamite to break up the coal seam, after which the coal is gathered and loaded onto shuttle cars or conveyors for removal to a central loading area. This process consists of a series of operations that begins with “cutting” the coalbed so it will break easily when blasted with explosives. This type of mining accounts for less than 5 percent of total underground production in the US today.[citation needed]
  • Shortwall mining, a method currently accounting for less than 1 percent of deep coal production, involves the use of a continuous mining machine with movable roof supports, similar to longwall. The continuous miner shears coal panels 150 to 200 feet (45 to 60 metres) wide and more than a half-mile (1 km) long, having regard to factors such as geological strata.[citation needed]
  • Retreat mining is a method in which the pillars or coal ribs used to hold up the mine roof are extracted; allowing the mine roof to collapse as the mining works back towards the entrance. This is one of the most dangerous forms of mining, owing to imperfect coal open pit mining of when the roof will collapse and possibly crush or trap workers in the mine.[citation needed]

Production[edit]

Main article: Major coal producing regions

Coal is mined commercially in over 50 countries. Over 7,036 Mt/yr of coal open pit mining coal visual data mining produced in 2007, a substantial increase over the previous 25 years.[9] In 2006, the world production of brown coal (lignite) was slightly over 1,000 Mt, with Germany the world’s largest brown coal producer at 194.4 Mt, and China second at 100.6 Mt.[10]

Coal production has grown fastest in Asia, while Europe has declined. Since 2013, the world coal production is decreasing, -6% in 2016.[11] The top coal mining nations are:

Most coal production is used in the country of origin, with around 16 percent of hard coal production being exported.

Coal reserves are available in almost every country worldwide, with recoverable reserves in around 70 countries. At current production levels, proven coal reserves are estimated to last 147 years.[13] However, production levels are by no means level, and are in fact increasing and some estimates are that peak coal could arrive in many countries such as China and America by around 2030. Coal reserves are usually stated as either (1) "Resources" ("measured" + "indicated" + "inferred" = "resources", and then, a smaller number, often only 10-20% of "resources," (2) "Run of Mine" (ROM) reserves, and finally (3) "marketable reserves", which may be only 60% of ROM reserves.[clarification needed] The standards for reserves are set by stock exchanges, in consultation with industry associations. For example, in ASEAN countries reserves standards follow the Australasian Joint Ore Reserves Committee Code (JORC) used mining rig monitoring the Australian Securities Exchange.

Modern mining[edit]

Technological advancements have made coal mining today more productive than it has ever been. To keep up with technology and to extract coal as coal open pit mining as possible modern mining personnel must be highly skilled and well trained in the use of complex, state-of-the-art instruments and equipment. Many jobs require four-year university degrees. Computer knowledge has also become greatly valued within the industry as most of the machines and safety monitors are computerized.

The use of sophisticated sensing equipment to monitor air quality is common and has replaced the use of small animals such as canaries, often referred to as "miner's canaries".[14]

In the United States, the increase in technology has significantly decreased the mining workforce. in 2015 US coal mines had 65,971 employees, the lowest figure since EIA began collecting data in 1978.[15] However, a 2016 study reported that a relatively minor investment would allow most coal workers to retrain for the solar energy industry.[16]

Safety[edit]

See also: Mine safety and Mining accident

Dangers to miners[edit]

Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. In the US alone, more than 100,000 coal miners were killed in accidents in the twentieth century,[17] 90 percent of the fatalities occurring in the first half of the century.[18] More than 3,200 died in 1907 alone.[19]

Open cut hazards are principally mine wall failures and vehicle collisions; underground mining hazards include suffocation, gas poisoning, roof collapse, rock burst, outbursts, and gas explosions.

Firedamp explosions can trigger the much-more-dangerous coal dust explosions, which can engulf an entire pit. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in some parts of the developed world. Modern mining in the US results in approximately 30 deaths per year due to mine accidents.[20]

However, in lesser developed countries coal open pit mining some developing countries, many miners continue to die annually, either through direct accidents in coal mines or through adverse health consequences from working under poor conditions. China, in particular, has the highest number of coal mining coal open pit mining deaths in the world, with official statistics claiming that 6,027 deaths occurred in 2004.[21] To compare, 28 deaths were reported in the US in the same year.[22] Coal production in China is twice that in the US,[23] while the number of coal miners is around 50 times that of the US, making deaths in coal mines in China 4 times as common per worker (108 times as common per unit output) as in the US.

Mine disasters have still occurred in recent years in the US,[24] Examples include the Sago Mine disaster of 2006, and the 2007 mine accident in Utah's Crandall Canyon Mine, where nine miners were killed and six entombed.[25] In the decade 2005-2014, US coal mining fatalities averaged 28 per year.[26] The most fatalities during the 2005-2014 decade were 48 in 2010, the year of the Upper Big Branch Mine disaster in West Virginia, which killed 29 miners.[27]

Chronic lung diseases, such as pneumoconiosis (black lung) were once common in miners, coal open pit mining, leading to reduced life expectancy. In some mining countries black lung is still common, with 4,000 new cases of black lung every year in the US (4 percent of workers annually) and 10,000 new cases every year in China (0.2 percent of workers).[28] Rates may be higher than reported in some regions.

Build-ups of a hazardous gas are known as damps, possibly from the German word "Dampf" which means steam or vapor:

Dangers from mining waste[edit]

In the 1966 Aberfan disaster in Wales, a colliery spoil tip collapsed, engulfing a school and killing 116 children and 28 adults. Other accidents involving coal waste include the Martin County coal slurry spill (USA, 2000) and the Obed Mountain coal mine spill (Canada, 2013).

Safety Improvements[edit]

Improvements in mining methods (e.g. longwall mining), hazardous gas monitoring coal open pit mining as safety-lamps or more modern electronic gas monitors), gas drainage, electrical equipment, and ventilation have reduced many of the risks of rock falls, explosions, and unhealthy air quality. Gases released during the mining process can be recovered to generate electricity and improve worker safety with gas engines.[29] Another innovation in recent years is the use of closed circuit escape respirators, mining and energy industry that contain oxygen for situations where mine ventilation is compromised.[30] Statistical analyses performed by the US Department of Labor’s Mine Safety and Health Administration (MSHA) show that between 1990 and 2004, the industry cut the rate of injuries by more than half and fatalities by two-thirds. However, according to the Bureau of Labor Statistics, even in 2006, mining remained the second most dangerous occupation in America, when measured by fatality rate.[31][verification needed] However, these numbers include all mining, with oil and gas mining contributing the majority of fatalities; coal mining resulted in only 47 fatalities that year.[31]

Environmental impacts[edit]

Main article: Environmental impact of the coal industry

Coal mining can result in a number of adverse effects on the environment.

Surface mining of coal completely eliminates existing vegetation, destroys the genetic soil profile, displaces or destroys wildlife and habitat, degrades air quality, alters current land uses, and to some extent permanently changes the general topography of the area mined.[32] This often results in a scarred landscape with no scenic value. Of greater concern, the movement, storage, and redistribution of soil during mining can disrupt the community of soil microorganisms and consequently nutrient cycling processes. Rehabilitation or reclamation mitigates some of these concerns and is required by US Federal Law, specifically the Surface Mining Control and Reclamation Act of 1977.

Mine dumps (tailings) could produce acid mine drainage which can seep into waterways and aquifers, with consequences on ecological and human health.

If underground mine tunnels collapse, they cause subsidence of the ground above. Subsidence can damage buildings, and disrupt the flow of streams and rivers by interfering with the natural drainage.

Coal production is a major contributor to global warming: burning coal generates large quantities of carbon dioxide and mining operations can release methane, a known greenhouse gas, into the atmosphere. The coal mining industry is working to improve its public image.[33]

Coal mining by country[edit]

See also: Coal in Europe

Top 10 hard and brown coal producers in 2012 were (in million metric tons): China 3,621, United States 922, India 629, Australia 432, Indonesia 410, Russia 351, South Coal open pit mining 261, Germany 196, Poland 144, and Kazakhstan 122.[34][35]

Australia[edit]

Main article: Coal mining in Australia

Coal is mined in every state of Australia, but mainly in Queensland, New South Wales and Victoria. It is mostly used to generate electricity, and 75% of coal open pit mining coal production is exported, mostly to eastern Asia.

In 2007, 428 million tonnes of coal was mined in Australia.[9] In 2007, coal provided about 85% of Australia's electricity production.[36] In fiscal year 2008/09, 487 million tonnes of coal was mined, and 261 million tonnes was exported.[37] In fiscal year 2013/14, 430.9 million tonnes of coal was mined, and 375.1 million tonnes was exported.[38] In 2013/14, coal provided about 69% of Australia's electricity production.[39]

In 2013, Australia was the world's fifth-largest coal producer, after China, the United States, India, and Indonesia. However, in terms of proportion of production exported, Australia is the world's second largest coal exporter, as it exports roughly 73% of its coal production. Indonesia exports about 87% of its coal production.[39]

Canada[edit]

Canada was ranked as the 15th coal producing country in the world in 2010, with a total production of 67.9 million tonnes, coal open pit mining. Canada's coal reserves, the 12th largest in the world, are located largely in the province of Alberta.[40]

The first coal mines in North America were located in Joggins and Port Morien, Nova Scotia, mined by French settlers beginning in the late 1600s. The coal was used for the British garrison at Annapolis Royal, and in construction of the Fortress of Louisbourg.

Chile[edit]

Main article: Coal mining in Chile

Compared to other South American countries Chile has limited coal resources. Only Argentina is similarly poor.[41] Coal is Chile is mostly mining misappropriation with the exception of the bituminous coals of the Arauco Basin in central Chile.[42]

China[edit]

Main article: Coal power in China

The People's Republic of China is by far the largest producer of coal in the world, producing over 2.8 billion tons of coal in 2007, or approximately 39.8 percent of all coal produced in the world during that year.[9] For comparison, the second largest producer, the United States, produced more than 1.1 billion tons in 2007. An estimated 5 million people work in China's coal-mining industry. As many as 20,000 miners die in accidents each year.[43] Most Chinese mines are deep underground and do not produce the surface disruption typical of strip mines. Although there is some evidence of reclamation of mined land for use as parks, China does not require extensive reclamation and is creating significant acreages of abandoned mined land, which is unsuitable for agriculture or other human uses, and inhospitable to indigenous wildlife. Chinese underground mines often experience severe surface subsidence (6–12 meters), negatively impacting farmland because it no longer drains well. China uses some subsidence areas for aquaculture ponds but has more than they need for that purpose. Reclamation of subsided ground is a significant problem in China. Because most Chinese coal is for domestic consumption, coal open pit mining, and is burned with little or no air pollution control equipment, it contributes greatly to visible smoke and severe air pollution in industrial areas using coal for fuel, coal open pit mining. China's total energy uses 67% from coal mines.

Colombia[edit]

Some of the world's largest coal reserves are located in South America, and an opencast mine at Cerrejón in Colombia is coal open pit mining of the world's largest open pit mines. Output of the mine in 2004 was 24.9 million tons (compared to total global hard coal production of 4,600 million tons). Cerrejón contributed about half of Colombia's coal exports of 52 million tons that year, with Colombia ranked sixth among major coal exporting nations. The company planned to expand production to 32 million tons by 2008. The company has its own 150 km standard-gauge railroad, connecting the mine to its coal-loading terminal at Puerto Bolívar mining deposit the Caribbean coast. There are two 120-car unit trains, each carrying 12,000 tons of coal per trip. The round-trip time for each train, including loading and unloading, is coal open pit mining 12 hours. The coal facilities at the port are capable of loading 4,800 tons per hour onto vessels coal open pit mining up to 175,000 tons of dead weight. The mine, railroad and port operate 24 hours per day. Cerrejón directly employs 4,600 workers, with a further 3,800 employed by contractors. The reserves at Cerrejón are low-sulfur, low-ash, bituminous coal. The coal is mostly used for electric power generation, with some also used in steel manufacture. The surface mineable reserves for the current contract are 330 million tons. However, total proven reserves to a depth of 300 metres are 3,000 million tons.

The expansion of the Cerrejón mine has been blamed for the forced displacement of local communities.[44][45]

Germany[edit]

Germany has a long history of coal mining, going back to the Middle Ages. Coal mining greatly increased during the industrial revolution and the following decades. The main mining areas were around Aachen, the Ruhr and Saar area, along with many smaller areas in other parts of Germany. These areas grew and were shaped by coal mining and coal processing, and this is still visible even after the end of the coal mining.

Coal mining reached its peak in the first half of the 20th century. After 1950, the coal producers started to struggle financially. In 1975, coal open pit mining, a subsidy was introduced (Kohlepfennig). In 2007, the Bundestag decided to end subsidies by 2018. As a consequence, RAG Aktiengesellschaft, the owner of the two remaining coal mines in Germany, announced coal open pit mining would close all mines by 2018, thus ending coal mining in Germany.

India[edit]

Main article: Coal mining in India

Coal mining in India has a long history of commercial exploitation starting in 1774 with John Sumner and Suetonius Grant Heatly of the East India Company in the Raniganj Coalfield along the Western bank of Damodar River. Demand for coal remained low until the introduction of steam locomotives in 1853. After this, production rose to an annual average of 1 Mt and India produced 6.12 Mt per year by 1900 and 18 Mt per year by 1920, following increased demand in the First World War, but went through a slump in the early thirties. The production reached a level of 29 Mt by 1942 and 30 Mt by 1946. After independence, the country embarked upon five-year development plans. At the beginning nvidia 980 mining the 1st Plan, annual production went up to 33 Mt. During the 1st Plan period, the need for increasing coal production efficiently by systematic and scientific development of the coal industry was being felt. Setting up the National Coal Development Corporation (NCDC), a Government of India undertaking, in 1956 with the collieries owned by the railways as its nucleus was the first major step towards planned development of Indian Coal Industry. Along with the Singareni Collieries Company Ltd. (SCCL) which was already in operation since 1945 and which became a government company under the control of Government of Andhra Pradesh in 1956, India thus had two Government coal companies in the fifties. SCCL is now a joint undertaking of Government of Telangana and Government of India.

Japan[edit]

Main article: List of coal mines in Japan

The richest Japanese coal deposits have been found on Hokkaidō and Kyũshũ.

Japan has a long history of coal mining dating back into the Japanese Middle Ages. It is said that coal was first discovered in 1469 by a farming couple near Ōmuta, central Kyūshū.[46] In 1478, farmers discovered burning stones in the north of the island, which led to the exploitation of coal open pit mining Chikuhõ coalfield.[47]

Following Japanese industrialization additional coalfields were discovered northern Japan. One of the first mines in Hokkaidō was the Hokutan Horonai coal mine.[48]

Poland[edit]

Main article: Coal mining in Poland

Russia[edit]

Russia ranked as the fifth largest coal producing country in 2010, with a total production of 316.9 Mt, coal open pit mining. Russia has the world's second largest coal reserves.[49] Russia and Norway share the coal resources of the Arctic archipelago of Svalbard, under the Svalbard Treaty.[citation needed]

Spain[edit]

Spain was ranked as the 30th coal producing country in the world in 2010. The coal miners of Spain were active in the Spanish Civil War on the Republican side. In October 1934, in Asturias, union miners and others suffered a fifteen-day siege in Oviedo and Gijon, coal open pit mining. There is a museum dedicated to coal mining in the region of Catalonia, called Cercs Mine Museum.

South Africa[edit]

Main article: Coal in South Africa § Mining

South Africa is one of the ten largest coal producing countries[50][51] and the fourth largest coal exporting country[52] in the world.

Taiwan[edit]

In Taiwan, coal is distributed mainly in the northern area. All of the commercial coal deposits occurred in three Miocene coal-bearing formations, which are the Upper, coal open pit mining, the Middle and the Lower Coal Measures. The Middle Coal Measures was the most important with its wide distribution, great number of coal beds and extensive potential reserves. Taiwan has coal reserves estimated to be 100-180 Mt. However, coal output had been small, amounting to 6,948 metric tonnes per month from 4 pits before it ceased production effectively in 2000.[53] The abandoned coal mine in Pingxi District, New Taipei has now turned into the Taiwan Coal Mine Museum.[54]

Ukraine[edit]

Main article: Coal in Ukraine

In 2012 coal production in Ukraine amounted to 85.946 million tonnes, up 4.8% from 2011.[55] Coal consumption that same year grew to 61.207 million tonnes, coal open pit mining, up 6.2% compared with 2011.[55]

More than 90 percent of Ukraine’s coal production comes from the Donets Basin.[56] The country's coal industry employs about 500,000 people.[57] Ukrainian coal mines are among the mining truck trolley dangerous in the world, and accidents are common.[58] Furthermore, the country is plagued with extremely dangerous illegal mines.[59]

United Kingdom[edit]

Main article: Coal mining in the United Kingdom

Before the industrial coal open pit mining much of the coal was used near to its production, although there was an active trade along coal open pit mining North Sea coast supplying coal to Yorkshire and London.[1]

Many coalfields were developed in the industrial revolution, coal open pit mining. The oldest coal open pit mining in Newcastle and Durham, South Wales, the Central Belt of Scotland and the Coal open pit mining, such as those at Coalbrookdale. The oldest continuously worked deep-mine in the United Kingdom was Tower Colliery in the South Wales coalfield, coal open pit mining. This colliery was developed in 1805, and its miners bought it out at the end of the 20th century, to prevent it from being closed. Specialized mining vehicles Colliery was finally closed on 25 January 2008.[60]

The United Kingdom was ranked as the 24th coal producing country in the world in 2010, with a total production of 18.2 million tonnes. Coal mining in the United Kingdom probably dates to Roman times; coal production increased significantly during the Industrial Revolution in the 19th century and peaked during World War I. As a result of its long history with coal Britain's economically recoverable coal reserves have coal open pit mining and more than twice as much coal is now imported than produced.[62]

United States[edit]

Coal miners leaving an American mine at the end of a shift (April 1974)
Surface coal mining in Wyoming in the United States.
A coal mine in Bihar, India.
Ships have been used to haul coal since Roman times.
Remote Joy HM21 Continuous Miner used underground
Coal production trends 1980-2012 in the top five coal-producing countries (US EIA)
Laser profiling of a minesite by a coal miner using a Maptek I-site laser scanner in 2014
Miners can be regularly monitored for reduced lung function due to coal dust exposure using spirometry.
A video on the use of roof screens in underground coal mines
The six largest countries by coal production in 2015 as determined by the US Energy Information Agency.
The Daikōdō (大抗道), the first adit of the Horonai mine (1879).(also known as the Otowakõ (音羽坑))
A view of Murton colliery near Seaham, United Kingdom, 1843
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Basics of an open pit mine

Coal Mining Technologies. Coal Strip and auger mining are the two most common surface methods of extracting coal in the United States. Open-pit mining is. OPEN PIT MINING - Download as PDF File .pdf), Text File .txt) or read online. Open pit mining is the process of mining a near surface deposit by means of a surface pit excavated using one or more horizontal benches. The term open pit mining is. Quit Coal; Coal mining impacts About 40 percent of the world’s coal mines are the more damaging strip mines (also called open cast, open pit.

Basics of an open pit mine. Photo of Magma Copper's Open Pit Mine In Arizona. Fig. 1, Open pit mines can be used in coal mining. Quit Coal; Coal mining impacts About 40 percent of the world’s coal mines are the more damaging strip mines (also called open cast, open pit. Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow.


Open-pit mining or opencast mining refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow. It is a form of surface mining. The term is used to differentiate this form of mining from extractive methods that require tunneling into the earth, like longwall mining.[1]

Open-pit mines are used when deposits of minerals or rock are found near the surface; that is, where the overburden (surface material) is relatively thin or the area is structurally unsuitable for tunneling (e.g. sand, cinder, and gravel). For minerals that occur deep below the surface—where the overburden is thick—underground mining methods are commonly used.[1]

The process begins with the top layers of the land being removed. After that, layer after layer is taken away until the coal is visible. The coal is taken out, processed, and sold. Taking away layer after layer of land creates a gigantic, open hole or pit. Explosives like dynamite are used when miners want to remove large blocks of materials. Open-pit mines are typically enlarged until either the coal is exhausted, or an increasing ratio of overburden makes further mining uneconomic. When this occurs, the exhausted mines are sometimes converted to landfills for disposal of solid wastes. However, some form of water control is usually required to keep the mine pit from becoming a lake.[1]

Environmental effects

Acid mine drainage

Acid mine drainage (AMD) refers to the outflow of acidic water from coal or metal mines, where mining has exposed rocks containing the sulphur-bearing mineral pyrite. Pyrite reacts with air and water to form sulphuric acid and dissolved iron, and as water washes through mines, this compound forms a dilute acid, which can wash into nearby rivers and streams.[2]

When large quantities of rock containing sulphide minerals are excavated from an open pit or opened up in an underground mine, it reacts with water and oxygen to create the sulphuric acid. When the water reaches a certain level of acidity, a naturally occurring type of bacteria called Thiobacillus ferroxidans may kick in, accelerating the oxidation and acidification processes, leaching even more trace heavy metals from the wastes. The acid will leach from the rock as long as its source rock is exposed to air and water and until the sulphides are leached out – a process that can last hundreds, even thousands of years. Acid is carried off the minesite by rainwater or surface drainage and deposited into nearby streams, rivers, lakes and groundwater. AMD can severely degrade water quality, and can kill aquatic life and make water virtually unusable.[3]

Erosion

Erosion and sedimentation mineral development disturbs soil and rock in the course of constructing and maintaining roads, open pits, and waste impoundments. In the absence of adequate prevention and control strategies, erosion of the exposed earth may carry substantial amounts of sediment into streams, rivers and lakes. Excessive sediment can clog riverbeds and smother watershed vegetation, wildlife habitat and aquatic organisms.[3]

Water pollution

Water pollution problems caused by mining include acid mine drainage, heavy metal contamination, and increased sediment levels in streams. Sources can include active or abandoned open-pit mines, and their associated processing plants, coal sludge and coal waste-disposal areas, and haulage roads. Sediments, typically from increased soil erosion, cause siltation or the smothering of streambeds, affecting fisheries, swimming, domestic water supply, irrigation, and other uses of streams.[4]

Resources

References

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  1. the environmental impact of mining activities

    status of mining industry

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