Commodity Knowledge
Commodity Knowledge
Anthracite (Greek (anthrakítes), "coal-like," (ánthrax), coal) is a hard, compact variety of mineral coal that has a high luster. It has the highest carbon count, the fewest impurities, and the highest calorific content of all types of coals, which also include bituminous coal and lignite.

Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92.1% 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, 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 lion's share of production; other producers are Russia, Ukraine, North Korea, Vietnam, the UK, Australia and the US. Total production in 2010 was 670 million tons.

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, its higher relative density of 1.3-1.4, and lustre, 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 into anthracite.

The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 25 million Btu/ton (29 MJ/kg), 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 steam electric power generation.

Anthracite may be considered to be a transition stage between ordinary bituminous 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 earth-movements, such as the flanks of great mountain ranges. Anthracite is a product of metamorphism and is associated with metamorphic rocks, just as bituminous is associated with sedimentary rocks.
  • Because of its higher quality, anthracite generally costs two to three times as much as regular coal.
  • From the late 19th century until the 1950s, anthracite was the most popular fuel for heating homes and other buildings in the northern United States, until it was supplanted first by oil burning systems and more recently by natural gas systems as well. Many large public buildings, such as schools, were heated with anthracite-burning furnaces through the 1980s.
  • Current U.S. anthracite production averages around 5 million tons per year.
  • 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 an authorised fuel in terms of the United Kingdom's Clean Air Act 1993, meaning that it can 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
  • As petroleum and natural gas have become more expensive, anthracite coal may grow in its importance as an energy source.
  • 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.
  • The largest fields of anthracite coal in the United States are found in northeastern Pennsylvania called the Coal Region, where there are 7 billion short tons (6.3 billion tonnes) of minable reserves.
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