76-415: R. W. Miller was an Australian company that had interests in coal mining , pubs and shipping . The company was named after its founder Robert William Miller (1879-1958). R. W. Miller was founded in 1923 as a colliery proprietor and coal dealer. It became involved in the coastal coal-carrying trade of New South Wales to convey coal between Newcastle and Sydney . R. W. Miller owned many coal mines in
152-705: A 70% increase over the 20 years since 1999. In 2018, the world production of brown coal (lignite) was 803.2 Mt, with Germany the world's largest producer at 166.3 Mt. China is most likely the second largest producer and consumer of lignite globally although specific lignite production data is not made available. Coal production has grown fastest in Asia, while Europe has declined. Since 2011, world coal production has been stable, with decreases in Europe and US offset by increases from China, Indonesia and Australia. The top coal mining nations are: Energy production from coal mining
228-467: 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 the ridge and hilltops as flattened plateaus. 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. Spoil
304-405: A fourth of the world's energy. Coal extraction methods vary depending on whether the mine is an underground mine or a surface (also called an open cast) mine. Additionally, coal seam thickness and geology are factors in the selection of a mining method. The most economical method of coal extraction for surface mines is the electric shovel or drag line. The most economical form of underground mining
380-403: 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, explosives are first used in order to break through
456-440: A land use condition is not equal to the original use. Existing land uses (such as livestock grazing, crop and timber production) are temporarily eliminated in mining areas. High-value, intensive-land-use areas like urban and transportation systems are not usually affected by mining operations. If mineral values are sufficient, these improvements may be removed to an adjacent area. Strip mining eliminates existing vegetation, destroys
532-440: A large dining-room table, but with hydraulic jacks for legs. 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: Coal is mined commercially in over 50 countries. 7,921 million metric tons (Mt) of coal were produced in 2019,
608-447: A method that currently accounts for about 60 percent of world coal production. In deep mining, the room and pillar or bord and pillar method progresses along the seam, while pillars and 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 ,
684-421: A new coal mine. Peak coal Peak coal is the peak consumption or production of coal by a human community. Peak coal can be driven by peak demand or peak supply. Historically, it was widely believed that the supply-side would eventually drive peak coal due to the depletion of coal reserves . However, since the increasing global efforts to limit climate change , peak coal has been driven by demand. This
760-535: A possible future outlook, was published in scientific journals on coal geology in 2009. In 1956, Hubbert estimated that US coal extraction would peak in about the year 2150. In 2004, Gregson Vaux used the Hubbert model to predict peak US coal extraction in 2032. In 2014, a model published in the International Journal of Coal Geology forecast a U.S. raw tonnage peak from between 2009 and 2023, with
836-589: A result of occupational exposures is coined occupational hearing loss . To protect miners' hearing, the US Mine Safety and Health Administration 's (MSHA) guidelines for noise place a Permissible Exposure Limit (PEL) for noise at 90 dBA time-weighted over 8 hours. A lower cutoff, 85 dBA, is set for a worker to fall into the MSHA Action Level which dictates that workers be placed into hearing conservation programs. Noise exposures vary depending on
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#1732780181575912-447: Is a dream," However, world coal production exceeded 8 billion tons per year in 2012 (8.2 billion), 2013 (8.19 billion), 2014 (8.085 billion), 2022 (8.3 billion), and 2023 (8.5 billion). M. King Hubbert's 1956 projections from the world extraction curve estimated that world coal production would peak at approximately six billion metric tons per year at about the year 2150. Coal: Resources and Future Production , published in 2007 by
988-575: 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
1064-427: 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, which can prevent cave-ins until the miners and their equipment have left a work area. The mobile roof supports are similar to
1140-418: Is dedicated to mining activities until it can be reshaped and reclaimed. If mining is allowed, resident human populations must be resettled off the mine site; economic activities, such as agriculture or hunting and gathering food and medicinal plants are interrupted. What becomes of the land surface after mining is determined by the manner in which the mining is conducted. Usually reclamation of disturbed lands to
1216-522: Is due in large part to the rapid expansion of natural gas and renewable energy. As of 2024 over 40% of all energy sector CO2 emissions are from coal, and many countries have pledged to phase-out coal . The peak of coal's share in the global energy mix was in 2008, when coal accounted for 30% of global energy production. Coal consumption is declining in the United States and Europe, as well as developed economies in Asia. However, consumption
1292-516: Is highly concentrated in certain jurisdictions, which also concentrates much of the social and economic impacts of the industry to these regions. The industry directly employs over seven million workers worldwide, which, in turn, creates millions of indirect jobs. In several parts of the world, producers have reached peak coal as some economies shift away from fossil fuels to address climate change. A 2020 study found that renewables jobs could feasibly be created in these geographies to replace many of
1368-484: Is mostly used to generate electricity, and 75% of annual coal production is exported, mostly to eastern Asia. In 2007, 428 million tonnes of coal was mined in Australia. In 2007, coal provided about 85% of Australia's electricity production. In the fiscal year 2008/09, 487 million tonnes of coal was mined, and 261 million tonnes was exported. In the fiscal year 2013/14, 430.9 million tonnes of coal
1444-667: Is now used primarily to refer to a peak and subsequent decline in global and national coal consumption. In 2016 experts estimated that China, the world's largest coal consumer, reached peak coal in 2013, and that the world may have passed peak coal. However, in 2017, for the first time in four years, demand for coal rose. As of 2015, China accounted for 50.0 percent of world coal consumption. Chinese coal consumption fell in 2014 and 2015. The last previous decline in Chinese coal consumption had been in 1997 and 1998. While consumption in China and
1520-417: Is partially economically recoverable. Coal refuse is distinct from the byproducts of burning coal, such as fly ash . Piles of coal refuse can have significant negative environmental consequences, including the leaching of iron, manganese, and aluminum residues into waterways and acid mine drainage . The runoff can create both surface and groundwater contamination. The piles also create a fire hazard, with
1596-593: 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 a 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. Most coal seams are too deep underground for opencast mining and require underground mining,
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#17327801815751672-436: 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 is 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
1748-515: Is removed and overburden dumped to the side. Dust, vibration, and diesel exhaust odors are created (affecting sight, sound, and smell). Residents of local communities often find such impacts disturbing or unpleasant. In case of mountaintop removal , tops are removed from mountains or hills to expose thick coal seams underneath. The soil and rock removed is deposited in nearby valleys, hollows and depressions, resulting in blocked (and contaminated) waterways. Removal of soil and rock overburden covering
1824-624: Is responsible for almost 40% of global coal exports worldwide, and much of its current electricity is generated from coal-fired power stations . There are tentative plans to very slowly phase out coal electricity generation in favor of gas , although these plans are still a topic of much debate in Australian politics. Groups such as the Australian Greens , suggest that coal be left in the ground to avoid its potential combustion either in Australia or in importer nations. Because most of
1900-660: 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). The use of water sprays in mining equipment reduces the risk to miners' lungs. Build-ups of a hazardous gas are known as damps, possibly from the German word Dampf which means steam or vapor: Noise is also a contributing factor to potential adverse effects on coal miners' health. Exposure to excessive noise can lead to noise-induced hearing loss . Hearing loss developed as
1976-551: Is still increasing in India and Southeast Asia, which compensates for the falls in other regions. Global coal consumption reached an all time high in 2023 at 8.5 billion tons. Although reserves of coal remain abundant, consumption of coal has declined in many countries. In 2016, Scotland closed its last coal-fired power plant, accommodated by an increase in nuclear power generation (to 42.8% of 2016 output). Scottish renewable energy comprised 42.9% of 2016 output. The term "peak coal"
2052-464: Is the long wall, which involves using two spinning drums with carbide bits that runs along sections of the coal seam. 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, quality, and depth; strength of materials above and below
2128-591: Is the point at which the maximum global coal production rate is reached, after which, according to the theory, the rate of production will enter a terminal decline. Coal is a fossil fuel formed from plant matter over the course of millions of years. It is a finite resource and thus considered to be a non-renewable energy source. There are two different possible peaks: one measured by mass (i.e. metric tons) and another by energy output (i.e. petajoules). The world average heat content per mass of mined coal rose from 8,020 BTU/lb. in 1989 to 9,060 BTU/lb. in 1999. Since 1999,
2204-435: Is used for both thermal and metallurgical coals . In New South Wales open casting for steam coal and anthracite is practiced. 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. Strip mining exposes coal by removing earth above each coal seam. This earth to be removed
2280-626: The Hunter Valley . In 1942, a brewery was purchased in Petersham . This was followed by the purchase of many pubs . In 1967, the Miller's Brewery was sold to Tooheys , followed by the pubs in 1968. In the late-1960s and early-1970s, TNT , Ampol and Howard Smith built up substantial shareholdings with takeover offers by the latter two resulting in a protracted takeover battle resulting in an important legal case and subsequent appeal to
2356-491: The Industrial Revolution , and coal provided the main source of primary energy for industry and transportation in industrial areas from the 18th century to the 1950s. Coal remains an important energy source. Coal is also mined today on a large scale by open pit methods wherever the coal strata strike the surface or are relatively shallow. Britain developed the main techniques of underground coal mining from
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2432-533: The Privy council , Howard Smith Ltd v Ampol Petroleum Ltd . In 1979, Howard Smith's shareholding was increased to 67% in 1979 when it acquired Ampol's shareholding and in February 1985 it took 100% ownership. In 1988, R. W. Miller merged with Coal & Allied . Coal mining Coal mining is the process of extracting coal from the ground or from a mine. Coal is valued for its energy content and since
2508-564: 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 is called a "pit", and above-ground mining structures are referred to as a " pit head ". In Australia , "colliery" generally refers to an underground coal mine. Coal mining has had many developments in recent years, from
2584-467: The Earth Watch Group, Canadian coal extraction peaked in 1997. Germany hit peak hard coal extraction in 1958 at 150 million tons. In 2005, hard coal extraction was around 25 million tons. Total coal extraction peaked in 1985 at 578 million short tons, declined sharply in the early 1990s following German reunification, and has been nearly steady since 1999. Total coal extraction in 2005
2660-561: The Energy Watch Group (EWG) found that global coal extraction could peak in as few as 15 years. However, the graphs in their 2013 report show a peak in 2020. Reporting on this, Richard Heinberg also noted that the date of peak annual energetic extraction from coal would likely come earlier than the date of peak in quantity of coal (tons per year) extracted as the most energy-dense types of coal had been mined most extensively. The Future of Coal by B. Kavalov and S. D. Peteves of
2736-474: The IEA predicted that coal use would plateau in 2022, whereas UBS bank forecasts 2023. In 2020 China set a carbon neutral target date. In 2021, the government ordered all coal mines to operate at full capacity at all times, including holidays; approved new mines, and eliminated restrictions on coal imports. As of 2020, over half of the world's coal-generated electricity was produced in China. In 2018 India
2812-662: The Institute for Energy (IFE), prepared for European Commission Joint Research Centre, reached conclusions similar to those of Energy Watch Group, and stated that "coal might not be so abundant, widely available and reliable as an energy source in the future". Kavalov and Peteves did not attempt to forecast a peak in extraction. In 2011 the US Energy Information Administration projected world coal consumption to increase through 2035. According to M. King Hubbert 's Hubbert peak theory , peak coal
2888-812: The U.S., 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. In the decade 2005–2014, US coal mining fatalities averaged 28 per year. 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. Chronic lung diseases, such as pneumoconiosis (black lung) were once common in miners, leading to reduced life expectancy . In some mining countries black lung
2964-624: 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. But according to the Bureau of Labor Statistics , even in 2006, mining remained the second most dangerous occupation in America, when measured by fatality rate . These numbers, however, include all mining activities, and oil and gas mining contribute to
3040-610: The United States and proposed mines under development. The coal mining industry employs almost 2.7 million workers. The History of coal mining goes back thousands of years, with early mines documented in ancient China, the Roman Empire and other early historical economies. It became important in the Industrial Revolution of the 19th and 20th centuries, when it was primarily used to power steam engines, heat buildings and generate electricity. Coal mining continues as an important economic activity today, but has begun to decline due to
3116-403: The United States declined in 2015, that of India continued to rise and, in 2015, India surpassed the United States and became the world's second-largest consumer of coal. As of 2018, the top coal-extracting countries were China (46.0%), India (9.5%), US (8.6%), Indonesia (6.8%), Australia (6.1%) China is the largest consumer and mines the most out of the countries that produce coal . In 2019
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3192-581: The coal mining jobs as part of a just transition ; however, renewable energy was not suitable in some of the geographies with high concentrations of miners, such as in China, which is far and away the leading coal-mining nation. Coal refuse (also described as coal waste, rock, slag, coal tailings, waste material, rock bank, culm, boney, or gob ) is the material left over from coal mining, usually as tailings piles or spoil tips . For every tonne of hard coal generated by mining, 400 kg (880 lb) of waste material remains, which includes some lost coal that
3268-497: 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. The contour mining method consists of removing overburden from
3344-863: The coal resource may cause burial and loss of topsoil, exposes parent material, and creates large infertile wastelands. Soil disturbance and associated compaction result in conditions conducive to erosion. Soil removal from the area to be surface-mined alters or destroys many natural soil characteristics, and reduces its biodiversity and productivity for agriculture. Soil structure may be disturbed by pulverization or aggregate breakdown. 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 Africa 261, Germany 196, Poland 144, and Kazakhstan 122. Coal has been mined in every state of Australia, but mainly in Queensland, New South Wales and Victoria. It
3420-478: The country's coal is exported it is vulnerable to reductions by importing countries such as China. Indonesia is the world's biggest thermal coal exporter. Government policy is unclear. Production peaked in 2018 at just over 100 million tonnes. Coal output peaked in 1913 in Britain at 287 Mt and now accounts for less than one percent of world coal extraction. 2007 extraction was around 15 Mt. According to
3496-657: The depression years of the 1930s. Coal extraction peaked again in the 1940s, then declined during the 1950s. Then coal extraction revived, and was on a nearly continual increasing trend from 1962 to 2008, exceeding the previous peaks. Extraction in 2008 was a record 1.17 billion short tons. High-BTU anthracite coal peaked in 1914; and declined from 44 million tons in 1950 to 1.6 million tons in 2007. Bituminous coal extraction has also been declining since 1990. The gap has been taken up by large increases in subbituminous coal extraction. Comprehensive analysis of historical trends in US coal extraction and reserve estimates, along with
3572-429: The developed world. Modern coal mining in the US has an average 23 deaths per year due to mine accidents (2001–2020). However, in lesser developed countries and 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 related deaths in
3648-455: The disruptive activities of blasting, ripping, and excavating coal. Stripping of overburden eliminates and destroys archeological and historic features, unless they are removed beforehand. The removal of vegetative cover and activities associated with the construction of haul roads, stockpiling of topsoil, displacement of overburden and hauling of soil and coal increase the quantity of dust around mining operations. Dust degrades air quality in
3724-424: The early days of men tunneling, digging, and manually extracting the coal on carts to large open-cut and longwall mines. Mining at this scale requires the use of draglines , trucks, conveyors , hydraulic jacks , and shearers. The coal mining industry has a long history of significant negative environmental impacts on local ecosystems, health impacts on local communities and workers, and contributes heavily to
3800-571: The fatalities occurring in the first half of the 20th century. 3,242 died in 1907, the worst year ever; in 2020 there were five. 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 far more dangerous coal dust explosions, which can engulf an entire mine. Most of these risks are greatly reduced in modern mines, and multiple fatality incidents are now rare in most parts of
3876-457: The genetic soil profile, displaces or destroys wildlife and habitat, alters current land uses, and to some extent permanently changes the general topography of the area mined. Adverse impacts on geological features of human interest may occur in a coal strip mine. Geomorphic and geophysical features and outstanding scenic resources may be sacrificed by indiscriminate mining. Paleontological, cultural, and other historic values may be endangered due to
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#17327801815753952-399: The global environmental crises, such as poor air quality and climate change . For these reasons, coal has been one of the first fossil fuels to be phased out of various parts of the global energy economy . The major coal producing countries, though, such as China , Indonesia, India and Australia , have not reached peak production, with production increases replacing falls in Europe and
4028-525: The growth leveled off. He concluded that no finite resource could sustain exponential growth. At some point, the rate of extraction will have to peak and then decline until the resource is exhausted. He theorized that extraction rate plotted versus time would show a bell-shaped curve, declining as rapidly as it had risen. Hubbert used his observation of the US coal extraction to predict the behavior of peak oil . The Hubbert linearization using yearly production rates has weaknesses for peak coal calculation, as
4104-450: The immediate area, has an adverse impact on vegetative life, and constitutes health and safety hazards for mine workers and nearby residents. Surface mining disrupts virtually all aesthetic elements of the landscape. Alteration of land forms often imposes unfamiliar and discontinuous configurations. New linear patterns appear as material is extracted and waste piles are developed. Different colors and textures are exposed as vegetative cover
4180-460: The late 18th century onward, with further progress being driven by 19th-century and early 20th-century progress. However, oil and gas were increasingly used as alternatives from the 1860s onward. By the late 20th century, coal was, for the most part, replaced in domestic as well as industrial and transportation usage by oil , natural gas or electricity produced from oil, gas, nuclear power or renewable energy sources. By 2010, coal produced over
4256-404: The majority of fatalities. Coal mining resulted in 47 fatalities that year. One study, though, has suggested that hazards of modern mining are now more accretive with workers facing long-term health impacts, such as sleep deprivation, that build up over time. Strip mining severely alters the landscape, which reduces the value of the natural environment in the surrounding land. The land surface
4332-461: The method of extraction. For example, a study has found that among surface coal mine operations, dragline equipment produced the loudest sound at a range of 88–112 dBA. Within longwall sections, stageloaders used to transport coal from the mining face and shearers used for extraction represent some of the highest noise exposures. Auxiliary fans (up to 120 dBA), continuous mining machines (up to 109 dBA), and roof bolters (up to 103 dBA) represent some of
4408-465: The mining workforce. in 2015 US coal mines had 65,971 employees, the lowest figure since EIA began collecting data in 1978. However, a 2016 study reported that a relatively minor investment would allow most coal workers to retrain for the solar energy industry. Coal mining has been a very dangerous activity and the list of historical coal mining disasters is long. In the U.S., 104,895 coal miners were killed in mine accidents since 1900, 90 percent of
4484-508: The most likely year of the peak in 2010. Over the years, the average energy content per ton of coal mined in the US has declined as mining shifts to coals of lower rank. Although the tonnage of coal mined in the United States reached its latest peak in 2008, the peak in terms of coal energy content occurred in 1998, at 598 Millions of metric tons of oil equivalent (Mtoe); by 2005 this had fallen to 576 Mtoe, or about 4% lower. Australia has substantial coal resources, mostly brown coal . It
4560-469: The noisiest equipment within continuous mining sections. Exposures to noise exceeding 90 dBA can lead to adverse effects on workers' hearing. The use of administrative controls and engineering controls can be used to reduce noise exposures. Improvements in mining methods (e.g. longwall mining), hazardous gas monitoring (such as safety-lamps or more modern electronic gas monitors), gas drainage, electrical equipment , and ventilation have reduced many of
4636-590: The open pit methods, due to thickness of the seam 20–25 metres (60–90 feet). Coals occurring below 90 m (300 ft) are usually deep mined. However, there are open pit mining operations working on coal seams up to 300–460 metres (1,000–1,500 feet) below ground level, for instance Tagebau Hambach in Germany. 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. Opencast coal mining recovers
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#17327801815754712-421: 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
4788-408: The overburden. 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 mining combines area and contour strip mining methods. In areas with rolling or steep terrain with
4864-425: The potential to spontaneously ignite. Because most coal refuse harbors toxic components, it is not easily reclaimed by replanting with plants like beach grasses. 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 ". In the United States, the increase in technology has significantly decreased
4940-399: 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 . Another innovation in recent years is the use of closed circuit escape respirators , respirators that contain oxygen for situations where mine ventilation is compromised. Statistical analyses performed by
5016-418: 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; groundwater conditions; availability of labor and materials; coal purchaser requirements in terms of tonnage, quality, and destination; and capital investment requirements. Surface mining and deep underground mining are
5092-565: 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
5168-432: 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 barrier 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
5244-556: The strong contribution coal plays in global warming and environmental issues, which result in decreasing demand and in some geographies, peak coal . Compared to wood fuels , coal yields a higher amount of energy per unit mass, specific energy or massic energy, and can often be obtained in areas where wood is not readily available. Though it was used historically as a domestic fuel, coal is now used mostly in industry, especially in smelting and alloy production, as well as electricity generation . Large-scale coal mining developed during
5320-476: The 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. Most open cast mines in the United States extract bituminous coal . In Canada, Australia, and South Africa, open cast mining
5396-524: 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 55 m (180 ft), are usually surface mined. Coal that occurs at depths of 55 to 90 m (180 to 300 ft) 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 60 m (200 ft) are mined by
5472-426: The world average heat content of mined coal has been fairly steady, and was 9,030 BTU/lb. in 2011. Hubbert concluded that each oil region and nation has a bell-shaped depletion curve . However, this question was originally raised by William Stanley Jevons in his book The Coal Question in 1865. Hubbert noted that United States coal extraction grew exponentially at a steady 6.6% per year from 1850 to 1910. Then
5548-441: The world, with official statistics claiming that 6,027 deaths occurred in 2004. To compare, 28 deaths were reported in the U.S. in the same year. Coal production in China is twice that in the US, 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
5624-588: Was 229 million short tons, four percent of total world extraction. In 2010, Tadeusz Patzek (chairman of the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin) and Greg Croft, predicted that coal production would peak in 2011 or shortly thereafter, and decline so quickly as to nearly eliminate the contribution of coal to climate change. Patzek said: "Our ability to produce this resource at 8 billion tons per year, in my mind,
5700-531: Was mined, and 375.1 million tonnes was exported. In 2013/14, coal provided about 69% of Australia's electricity production. 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. A court in Australia has cited climate change in ruling against
5776-410: Was the world's second largest coal producer. Partly due to the fall in cost of LPG and renewables peak consumption is forecast for the 2020s, or 2030. Although Hubbert's analysis in 1956 projected total extraction to peak in about 2150, records show that extraction reached an energy peak in 1998 and a tonnage peak in 2008. US coal extraction peaked during World War I , then declined sharply during
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