Anthracite, also known as hard coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.
Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 86% and 98%.The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition. Anthracite ignites with difficulty and burns with a short, blue, and smokeless flame.
Anthracite is categorized into standard grade, which is used mainly in power generation,[ contradictory ] and high grade (HG) and ultra high grade (UHG), the principal uses of which are in the metallurgy sector. Anthracite accounts for about 1% of global coal reserves, and is mined in only a few countries around the world. China accounts for the majority of global production; other producers are Russia, Ukraine, North Korea, South Africa, Vietnam, the UK, Australia, Canada and the US. Total production in 2010 was 670 million tons.
Anthracite derives from the Greek anthrakítēs (ἀνθρακίτης), literally "coal-like". Other terms which refer to anthracite are black coal, hard coal, stone coal, dark coal, coffee coal, blind coal (in Scotland), Kilkenny coal (in Ireland), crow coal or craw coal, and black diamond. "Blue Coal" is the term for a once-popular and trademarked brand of anthracite, mined by the Glen Alden Coal Company in Pennsylvania, and sprayed with a blue dye at the mine before shipping to its northeastern U.S. markets to distinguish it from its competitors.
Culm has different meanings in British and American English. In British English, "culm" is the imperfect anthracite of north Devon and Cornwall, which was used as a pigment. The term is also used to refer to some Carboniferous rock strata found in both Britain and in the Rhenish hill countries (the Culm Measures).Lastly, it may refer to coal exported from Britain during the 19th century. In American English, "culm" refers to the waste or slack from anthracite mining, mostly dust and small pieces not suitable for use in home furnaces.
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Anthracite is similar in appearance to the mineraloid jet and is sometimes used as a jet imitation.
Anthracite differs from ordinary bituminous coal by its greater hardness (2.75–3 on the Mohs scale),its higher relative density of 1.3–1.4, and luster, which is often semi-metallic with a mildly brown reflection. It contains a high percentage of fixed carbon and a low percentage of volatile matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed. Anthracitization is the transformation of bituminous coal into anthracite.
The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 26 to 33 MJ/kg (22 to 28 million Btu/short ton) on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 29 MJ/kg (25 million Btu/ton), on the as-received basis (i.e., containing both inherent moisture and mineral matter). Since the 1980s, anthracite refuse or mine waste has been used for coal power generation in a form of recycling. The practice known as reclamation is being applied to culm piles antedating laws requiring mine owners to restore lands to their approximate original condition.
Chemically, anthracite may be considered as a transition stage between ordinary bituminous coal and graphite, produced by the more or less complete elimination of the volatile constituents of the former, and it is found most abundantly in areas that have been subjected to considerable stresses and pressures, such as the flanks of great mountain ranges.Anthracite is associated with strongly deformed sedimentary rocks that were subjected to higher pressures and temperatures (but short of metamorphic conditions) just as bituminous coal is generally associated with less deformed or flat-lying sedimentary rocks. For example, the compressed layers of anthracite that are deep mined in the folded Ridge and Valley Province of the Appalachian Mountains of the Coal Region of East-central Pennsylvania are extensions of the same layers of bituminous coal that are mined on the generally flat lying and undeformed sedimentary rocks further west on the Allegheny Plateau of Kentucky and West Virginia, Eastern Ohio, and Western Pennsylvania. In the same way the anthracite region of South Wales is confined to the contorted portion west of Swansea and Llanelli, the central and eastern portions producing steam coal, coking coal and domestic house coals.
Structurally, anthracite shows some alteration by the development of secondary divisional planes and fissures so that the original stratification lines are not always easily seen. The thermal conductivity is also higher; a lump of anthracite feels perceptibly colder when held in the warm hand than a similar lump of bituminous coal at the same temperature. The chemical composition of some typical anthracites is given in the article coal.
Anthracite has a history of use in blast furnaces for iron smelting; however, it lacked the pore space of metallurgical coke, which eventually replaced anthracite.
In southwest Wales, anthracite has been burned as a domestic fuel since at least medieval times,when it was mined near Saundersfoot. More recently, large-scale mining of anthracite took place right across the western part of the South Wales Coalfield until the late 20th century. Mining continues but now on a smaller scale.
In the United States, anthracite coal history began in 1790 in Pottsville, Pennsylvania, with the discovery of coal made by the hunter Necho Allen in what is now known as the Coal Region. Legend has it that Allen fell asleep at the base of Broad Mountain and woke to the sight of a large fire because his campfire had ignited an outcrop of anthracite coal. By 1795, an anthracite-fired iron furnace had been built on the Schuylkill River.
Anthracite was first experimentally burned as a residential heating fuel in the US on 11 February 1808, by Judge Jesse Fell in Wilkes-Barre, Pennsylvania, on an open grate in a fireplace. Anthracite differs from wood in that it needs a draft from the bottom, and Judge Fell proved with his grate design that it was a viable heating fuel.[ citation needed ]
In spring 1808, John and Abijah Smith shipped the first commercially mined load of anthracite down the Susquehanna River from Plymouth, Pennsylvania, marking the birth of commercial anthracite mining in the United States. From that first mine, production rose to an all-time high of over 100 million tons in 1917.[ citation needed ]
Anthracite usage was inhibited by the difficulty of igniting it. This was a particular concern in smelting iron using a blast furnace. With the invention of hot blast in 1828, which used waste heat to preheat combustion air, anthracite became a preferred fuel, accounting for 45% of US pig iron production within 15 years.Anthracite for iron smelting was later displaced by coke.
From the late 19th century until the 1950s, anthracite was the most popular fuel for heating homes and other buildings in the northern US, until it was supplanted by oil-burning systems and more recently natural gas systems. Many large public buildings, such as schools, were heated with anthracite-burning furnaces through the 1980s.
During the American Civil War, Confederate blockade runners used anthracite as a smokeless fuel for their boilers to avoid giving away their position to the blockaders.
The invention of the Wootten firebox enabled locomotives to directly burn anthracite efficiently, particularly waste culm. In the early 20th century US, the Delaware, Lackawanna & Western Railroad started using only the more expensive anthracite coal in its passenger locomotives, dubbed themselves "The Road of Anthracite," and advertised widely that travelers on their line could make railway journeys without getting their clothing stained with soot. The advertisements featured a white-clad woman named Phoebe Snow and poems containing lines like "My gown stays white / From morn till night / Upon the road of Anthracite". Similarly, the Great Western Railway in the UK was able to use its access to anthracite (it dominated the anthracite region) to earn a reputation for efficiency and cleanliness unmatched by other UK companies.
Internal combustion motors driven by the so-called "mixed", "poor", "semi-water" or "Dowson gas" produced by the gasification of anthracite with air (and a small proportion of steam) were at one time the most economical method of obtaining power, requiring only 1 pound per horsepower-hour (0.6 kg / kWh ), or less. Large quantities of anthracite for power purposes were formerly exported from South Wales to France, Switzerland and parts of Germany. As of April 2013 [update] , widespread commercial anthracite mining in Wales has now ceased, although a few large open cast sites remain, along with some relatively small drift mining operations.[ citation needed ]
Anthracite generally costs two to three times as much as regular coal. In June 2008, the wholesale cost of anthracite was US$150/short ton.
The principal use of anthracite today is for a domestic fuel in either hand-fired stoves or automatic stoker furnaces. It delivers high energy per its weight and burns cleanly with little soot, making it ideal for this purpose. Its high value makes it prohibitively expensive for power plant use. Other uses include the fine particles used as filter media, and as an ingredient in charcoal briquettes. Anthracite was an authorised fuelin terms of the United Kingdom's Clean Air Act of 1993, meaning that it could be used within a designated Smoke Control Area such as the central London boroughs.
China today mines by far the largest share of global anthracite production, accounting for more than three-quarters of global output. [ citation needed ] Increased demand in China has made that country into a net importer of the fuel, mostly from Vietnam, another major producer of anthracite for power generation, although increasing domestic consumption in Vietnam means that exports may be scaled back.Most Chinese production is of standard-grade anthracite, which is used in power generation.
Current U.S. anthracite production averages around 5 million tons per year. Of that, about 1.8 million tons were mined in the state of Pennsylvania.Mining of anthracite coal continues to this day in eastern Pennsylvania, and contributes up to 1% to the gross state product. More than 2,000 people were employed in the mining of anthracite coal in 1995. Most of the mining as of that date involved reclaiming coal from slag heaps (waste piles from past coal mining) at nearby closed mines. Some underground anthracite coal is also being mined.
Countries producing HG and UHG anthracite include Russia and South Africa. HG and UHG anthracite are used as a coke or coal substitute in various metallurgical coal applications (sintering, PCI, direct BF charge, pelletizing). It plays an important role in cost reduction in the steel making process and is also used in production of ferroalloys, silicomanganese, calcium carbide and silicon carbide. South Africa exports lower-quality, higher-ash anthracite to Brazil to be used in steel-making.[ citation needed ]
Anthracite is processed into different sizes by what is commonly referred to as a breaker. The large coal is raised from the mine and passed through breakers with toothed rolls to reduce the lumps to smaller pieces. The smaller pieces are separated into different sizes by a system of graduated sieves, placed in descending order.Sizing is necessary for different types of stoves and furnaces.
Anthracite is classified into three grades, depending on its carbon content. Standard grade is used as a domestic fuel and in industrial power-generation. The rarer higher grades of anthracite are purer – i.e., they have a higher carbon content – and are used in steel-making and other segments of the metallurgical industries. Technical characteristics of the various grades of anthracite are as follows:[ citation needed ]
|Standard grade anthracite||High grade anthracite||Ultra High grade anthracite||Coke|
|Fixed carbon (minimum)||73%||80%||85%||84%|
Anthracite is divided by size mainly into applications that need lumps (typically larger than 10 mm) – various industrial processes where it replaces metallurgical coke, and domestic fuel – and those that need fines (less than 10 mm), such as sintering and pelletising.
The common American classification by size is as follows:[ citation needed ]
Lump, steamboat, egg and stove coals, the latter in two or three sizes, all three being above 1+1⁄2 in (38 mm) size on round-hole screens.
High grade (HG) and ultra high grade (UHG) anthracite are the highest grades of anthracite coal. They are the purest forms of coal, having the highest degree of coalification, the highest carbon count and energy content and the fewest impurities (moisture, ash and volatiles).
High grade and ultra high grade anthracite are harder than standard grade anthracite, and have a higher relative density. An example of a chemical formula for high-grade anthracite would be C240H90O4NS,representing 94% carbon. UHG anthracite typically has a minimum carbon content of 95%.
They also differ in usage from standard grade anthracite (used mainly for power generation), being employed mainly in metallurgy as a cost-efficient substitute for coke in processes such as sintering and pelletising, as well as pulverised coal injection (PCI) and direct injection into blast furnaces. They can also be used in water purification and domestically as a smokeless fuel.
HG and UHG anthracite account for a small percentage of the total anthracite market. The major producing countries are Russia, Ukraine, Vietnam, South Africa and the US.
|Name||Imperial (inches)||Metric (mm)|
|Chestnut||7⁄8–1+1⁄2 in||22–38 mm|
The primary sizes used in the United States for domestic heating are Chestnut, Pea, Buckwheat and Rice, with Chestnut and Rice being the most popular. Chestnut and Pea are used in hand fired furnaces while the smaller Rice and Buckwheat are used in automatic stoker furnaces. Rice is currently the most sought-after size due to the ease of use and popularity of that type of furnace.
In South Wales a less elaborate classification is adopted, but great care is exercised in hand-picking and cleaning the coal from particles of pyrites in the higher qualities known as best malting coals, which are used for kiln-drying malt.
Anthracite dust can be made into briquettes and is sold in the United Kingdom under trade names such as Phurnacite, Ancit and Taybrite.
Historically from time to time, underground seams of coal have caught fire, often from careless or unfortunate mining activities. The pocket of ignited coal is fed oxygen by vent paths that have not yet been discovered. These can smolder for years. Commonly, exhaust vents in populated areas are soon sensed and are sealed while vents in uninhabited areas remain undiscovered. Occasionally, vents are discovered via fumes sensed by passers-by, often in forested areas. Attempts to extinguish those remaining have at times been futile, and several such combustion areas exist today. The existence of an underground combustion site can sometimes be identified in the winter where fallen snow is seen to be melted by the warmth conducted from below. Proposals for harnessing this heat as geothermal energy have not been successful.
A vein of anthracite that caught fire in Centralia, Pennsylvania, in 1962 has been burning ever since, turning the once-thriving borough into a ghost town.
Among current producers, Russia, China and Ukraine have the largest estimated recoverable reserves of anthracite. Other countries with substantial reserves include Vietnam and North Korea.
Geologically, the largest most concentrated anthracite deposit in the world is found in the Lackawanna Coal Mine in northeastern Pennsylvania, United States in and around Scranton, Pennsylvania. Locally called the Coal Region, the deposit contains 480 square miles (1,200 km2) of coal-bearing rock which originally held 22.8 billion short tons (20.68 billion tonnes) of anthracite. The geographic region is roughly 100 miles (161 km) in length and 30 miles (48 km) in width. Because of historical mining and development of the lands overlying the coal, it is estimated that 7 billion short tons (6.3 billion tonnes) of minable reserves remain. The United States also contains several smaller deposits of anthracite, such as those historically mined in Crested Butte, Colorado.
The Groundhog Anthracite Deposit, located in British Columbia, Canada, is the largest previously undeveloped anthracite deposit in the world. It is owned by Australian publicly listed company, Atrum Coal and has 1.57 billion tonnes of high grade anthracite.
Anthracites of newer Tertiary or Cretaceous age are found in the Crowsnest Pass part of the Rocky Mountains in Canada and at various places in the Andes in Peru.
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands—called coal forests—that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times. However, many significant coal deposits are younger than this and originate from the Mesozoic and Cenozoic eras.
Coke is a grey, hard, and porous fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen or asphalt. It is of higher quality than lignite and Sub-bituminous coal, but of poorer quality than anthracite. Formation is usually the result of high pressure being exerted on lignite. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. These distinctive sequences, which are classified according to either "dull, bright-banded" or "bright, dull-banded", is how bituminous coals are stratigraphically identified.
Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, wood pellets, corn, wheat, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day.
Anthracite iron or Anthracite 'Pig Iron' is the substance created by the smelting together of anthracite coal and iron ore, that is using Anthracite coal instead of charcoal to smelt iron ores — and was an important historic advance in the late-1830s enabling great acceleration the industrial revolution in Europe and North America.
Sub-bituminous coal is a type of lower grade coal which contains 35%-45% carbon. The properties of this type are between those of lignite, the lowest grade coal, and those of bituminous coal, the second highest grade of coal. Sub-bituminous coal is primarily used as a fuel for steam-electric power generation.
Coal analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.
A coal breaker is a coal processing plant which breaks coal into various useful sizes. Coal breakers also remove impurities from the coal and deposit them into a culm dump. The coal breaker is a forerunner of the modern coal preparation plant.
Hot blast refers to the preheating of air blown into a blast furnace or other metallurgical process. As this considerably reduced the fuel consumed, hot blast was one of the most important technologies developed during the Industrial Revolution. Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces.
Smokeless fuel is a type of solid fuel which either does not emit visible smoke, or emits minimal amounts, during combustion. These types of fuel are becoming increasingly popular in areas which ban the use of coal and other fuels such as unseasoned or wet wood which produce much smoke. Open fires are still popular with many domestic consumers, especially for those living in older houses where open fireplaces have not been removed or replaced by stoves for example. All houses older than about 1970 are fitted with open fireplaces when coal was in widespread use for domestic heating. However, modern houses are rarely equipped with fireplaces and central heating with natural gas or electricity is the usual choice. As a result of many places banning smoke and pollution, some studies have shown that overall air quality has improved along with fewer annual deaths related to smoke. Many consider smokeless fuel to be the near future replacement of all other solid fuels which cause toxic smoke emissions. The term in general is used to refer to solid fuels, such as: anthracite, coke, charcoal and hexamine fuel tablets. Smoke free carbonaceous fuels are usually supplied in the form of standard pillow-shaped briquettes made from powdered coal or charcoal. Fuel tablets are used by campers and walkers for temporary cooking using a small folding metal stove.
Coal mining regions are significant resource extraction industries in many parts of the world. They provide a large amount of the fossil fuel energy in the world economy.
According to the United States Energy Information Administration (EIA), Pakistan may have over 9 billion barrels (1.4×109 cubic metres) of petroleum oil and 105 trillion cubic feet (3.0 trillion cubic metres) in natural gas (including shale gas) reserves.
Coal mining in the United States is an industry in transition. Production in 2017 was down 33% from the peak production of 1,162.7 million short tons in 2006. Employment of 50,000 coal miners is down from a peak of 883,000 in 1923. Generation of electricity is the largest user of coal, being used to produce 50% of electric power in 2005 and 27% in 2018. The U.S. is a net exporter of coal. U.S. coal exports, for which Europe is the largest customer, peaked in 2012. In 2015, the U.S. exported 7.0 percent of mined coal.
The history of coal mining in the United States goes back to the 1300s, when the Hopi Indians used coal. The first commercial use came in 1701, within the Manakin-Sabot area of Richmond, Virginia. Coal was the dominant power source in the United States in the late 1800s and early 1900s, and although in rapid decline it remains a significant source of energy in 2019.
The Pittsburgh Coal Seam is the thickest and most extensive coal bed in the Appalachian Basin; hence, it is the most economically important coal bed in the eastern United States. The Upper Pennsylvanian Pittsburgh coal bed of the Monongahela Group is extensive and continuous, extending over 11,000 mi2 through 53 counties. It extends from Allegany County, Maryland to Belmont County, Ohio and from Allegheny County, Pennsylvania southwest to Putnam County, West Virginia.
Sibanthracite Group is Russia's largest producer of metallurgical coal and world leader in the production and export of high quality UHG anthracite. All coal companies of the Group are managed by Management Company "Sibanthracite", having its offices in Moscow.
There are two types of coal found in Pennsylvania: anthracite and bituminous. Anthracite coal is a natural mineral with a high carbon and energy content that gives off light and heat when burned, making it useful as a fuel. It was possibly first used in Pennsylvania as a fuel in 1769, but its real history begins with a documented discovery near Summit Hill and the founding of the Lehigh Coal Mine Company in 1792 to sporadically send expeditions to the wilderness atop Pisgah Ridge to mine the deposits, mostly with notable lack of great success, over the next 22 years. The owners of this company were absentee management—reliant on teams of workers sent under a foreman to fell timber to build so called 'Arks', then mine coal around nine miles from the right bank Lehigh, then trek with mule loads to fill the boats for the trip down the rapid strewn Lehigh River, and then more than 60 miles (97 km) to Philadelphia docks on the unimproved often log choked Delaware River.
The US iron and steel industry has paralleled the industry in other countries in technological developments. In the 1800s, the US switched from charcoal to coke in ore smelting, adopted the Bessemer process, and saw the rise of very large integrated steel mills. In the 20th century, the US industry successively adopted the open hearth furnace, then the basic oxygen steelmaking process. Since the American industry peaked in the 1940s and 1950s, the US industry has shifted to small mini-mills and specialty mills, using iron and steel scrap as feedstock, rather than iron ore.
Metallurgical coal or coking coal is a grade of coal that can be used to produce good-quality coke. Coke is an essential fuel and reactant in the blast furnace process for primary steelmaking. The demand for metallurgical coal is highly coupled to the demand for steel. Primary steelmaking companies often have a division that produces coal for coking, to ensure a stable and low-cost supply.
Coal in Alberta is found in the Coalspur Formation in the Western Canada Sedimentary Basin in the foothills of southwestern Alberta. The Coalspur Formation, which has large quantities of high-quality coal, runs from south of the Wapiti River to the North Saskatchewan River. The Coalspur coal zone is about 120 metres (390 ft) to 200 metres (660 ft) thick.
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