Bituminous coal
Overview
 
Bituminous coal or black coal is a relatively soft coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 containing a tarlike substance called bitumen. It is of higher quality than lignite coal
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

 but of poorer quality than Anthracite. It is usually formed as a result of high pressure on lignite.

Bituminous coal is an organic sedimentary rock formed by diagenetic and sub metamorphic compression of peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

 bog material.

Bituminous coal has been compressed and heated so that its primary constituents are maceral
Maceral
A maceral is a component of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite and liptinite.- Inertinite :...

s vitrinite
Vitrinite
Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass . It is derived from the cell-wall material or...

, exinite
Exinite
Liptinite is an umbrella term used in coal geology, referring to the finely-ground and macerated remains found in coal deposits. It replaced the term Exinite as one of the four categories of kerogen. Liptinites were originally formed by spores, pollen, dinoflagellate cysts, leaf cuticles, and plant...

, and so on.
Encyclopedia
Bituminous coal or black coal is a relatively soft coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 containing a tarlike substance called bitumen. It is of higher quality than lignite coal
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

 but of poorer quality than Anthracite. It is usually formed as a result of high pressure on lignite.

Bituminous coal is an organic sedimentary rock formed by diagenetic and sub metamorphic compression of peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

 bog material.

Bituminous coal has been compressed and heated so that its primary constituents are maceral
Maceral
A maceral is a component of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite and liptinite.- Inertinite :...

s vitrinite
Vitrinite
Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass . It is derived from the cell-wall material or...

, exinite
Exinite
Liptinite is an umbrella term used in coal geology, referring to the finely-ground and macerated remains found in coal deposits. It replaced the term Exinite as one of the four categories of kerogen. Liptinites were originally formed by spores, pollen, dinoflagellate cysts, leaf cuticles, and plant...

, and so on. The carbon content of bituminous coal is around 60-80%; the rest is composed of water, air, hydrogen, and sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, which have not been driven off from the maceral
Maceral
A maceral is a component of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite and liptinite.- Inertinite :...

s.

The heat content of bituminous coal ranges from 21 million to 30 million Btu
British thermal unit
The British thermal unit is a traditional unit of energy equal to about 1055 joules. It is approximately the amount of energy needed to heat of water, which is exactly one tenth of a UK gallon or about 0.1198 US gallons, from 39°F to 40°F...

/ton (24 to 35 MJ/kg) on a moist, mineral-matter-free basis.

Bituminous coal is usually black, sometimes dark brown, often with well-defined bands of bright and dull material. Bituminous coal seams are stratigraphically identified by the distinctive sequence of bright and dark bands and are classified accordingly as either "dull, bright-banded" or "bright, dull-banded" and so on.

Bank density is approximately 1346 kg/m³ (84 lb/ft³). bBulk density typically runs to 833 kg/m³ (52 lb/ft³).

Uses

Bituminous coals are graded according to vitrinite reflectance, moisture content, volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 content, plasticity and ash content. Generally, the highest value bituminous coals have a specific grade of plasticity
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the...

, volatility and low ash content, especially with low carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....

, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, and sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

.

Plasticity
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the...

 is vital for coking as it represents its ability to gradually form specific plasticity phases during the coking process, measured by coal dilatation tests. Low phosphorus content is vital for these coals, as phosphorus is a highly deleterious (damaging) element in steel making.

Coking coal
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 is best if it has a very narrow range of volatility and plasticity. This is measured by the free swelling index test. Volatile content and swelling index are used to select coals for coke blending as well.

Volatility is also critical for steel-making and power generation, as this determines the burn rate of the coal. High volatile content coals, while easy to ignite often are not as prized as moderately volatile coals; low volatile coal may be difficult to ignite although it contains more energy per unit volume. The smelter must balance the volatile content of the coals to optimize the ease of ignition, burn rate, and energy output of the coal.

Low ash, sulfur, and carbonate coals are prized for power generation because they do not produce much boiler slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...

 and they do not require as much effort to scrub the flue gases to remove particulate matter. Carbonates are deleterious as they readily stick to the boiler apparatus. Sulfide contents are also deleterious in some fashion as this sulfur is emitted and can form smog
Smog
Smog is a type of air pollution; the word "smog" is a portmanteau of smoke and fog. Modern smog is a type of air pollution derived from vehicular emission from internal combustion engines and industrial fumes that react in the atmosphere with sunlight to form secondary pollutants that also combine...

, acid rain
Acid rain
Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...

 and haze pollution. Again, scrubbers on the flue gases aim to eliminate particulate and sulfur emissions.

Smithing coal

Smithing coal is a type of high quality bituminous coal
Bituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...

 ideally suited for use in a coal forge
Forge
A forge is a hearth used for forging. The term "forge" can also refer to the workplace of a smith or a blacksmith, although the term smithy is then more commonly used.The basic smithy contains a forge, also known as a hearth, for heating metals...

. It is as free from ash
Fly ash
Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal...

, sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, and other impurities as possible. The constituents of the coal should be as follows:
Constituent Percentage
Sulfur Not over 1%
Ash Not over 7%
Carbon Not less than 70%
Moisture Not over 12%

Coking coal

When used for many industrial processes, bituminous coal must first be "coked"
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 to remove volatile components. Coking is achieved by heating the coal in the absence of oxygen, which drives off volatile hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

s such as propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...

, benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

 and other aromatic hydrocarbons, and some sulfur gases. This also drives off a considerable amount of the contained water of the bituminous coal.

Coking coal is used in the manufacture of steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

, where carbon must be as volatile-free and ash-free as possible.

Coking coal is heated to produce coke, a hard, grey, porous material which is used to blast in furnaces for the extraction of iron from the iron ore.

Bituminous coal by geologic period

Bituminous coal in the United States is between 100 to 300 million years old.

Carboniferous coals

Much North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n coal was created in subsiding areas adjacent to the Appalachian Mountains
Appalachian Mountains
The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

 during the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...

 subperiod. A vast network of swamps covered large parts of North America at this time and much of the organic material created in these wetlands accumulated to form thick layers of peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

 (the precursor to coal) that were buried faster than they could decay.

Bituminous coal is mined in the Appalachia
Appalachia
Appalachia is a term used to describe a cultural region in the eastern United States that stretches from the Southern Tier of New York state to northern Alabama, Mississippi, and Georgia. While the Appalachian Mountains stretch from Belle Isle in Canada to Cheaha Mountain in the U.S...

n region, primarily for power generation. Mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 is done via both surface and underground mines. Pocahontas bituminous coal at one time fueled half the world's navies and today stokes steel mills and power plants all over the globe.

Permian coals

The second largest deposits of the world's bituminous coal are contained within Permian strata in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. Australian deposits in the Bowen Basin
Bowen Basin
The Bowen Basin contains the largest coal reserves in Australia. This major coal producing region contains one of the world's largest deposits of bituminous coal. The Basin contains much of the known Permian coal resources in Queensland including virtually all of the known mineable prime coking coal...

 in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

, the Sydney Basin
Sydney Basin
The Sydney Basin is a sedimentary basin on the east coast of New South Wales, Australia consisting of Permian and Triassic sedimentary rocks...

 and Perth
Perth, Western Australia
Perth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....

 Basin are Permian coal, where thicknesses in excess of 300 m are known. Current reserves and resources are projected to last for over 200 years.

Australia exports the vast majority of its coal for coking and steel making in Japan. Certain Australian coals are the best in the world for these purposes, requiring little to no blending. Some bituminous coals from the Permian and Triassic in Australia are also the most suitable for cracking into oil
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

.

Triassic coals

Coals of Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 age are known from the Clarence-Moreton and Ipswich Basins, near Ipswich, Australia and the Esk Trough. Coals of this era are rare, and many contain fossils of flowering plants. Some of the best coking coals are Australian Triassic coals, although most economic deposits have been worked out.

Jurassic coals

Extensive but low-value coals of Jurassic age extend through the Surat Basin
Surat Basin
The Surat Basin is a part of the Great Artesian Basin of Australia. The Surat Basin extends across an area of 270,000 square kilometres and the southern third of the basin occupies a large part of northern New South Wales, the remainder is in Queensland. It comprises Jurassic through to Cretaceous...

 in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, formed in an intracratonic sag basin, and contain evidence of dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 activity in the numerous ash plies. These coals are exploited in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

 from the Walloon Coal Measures, which are up to 15m thick of sub-bituminous to bituminous coals suited for coking, steam-raising and oil cracking.

See also

  • Big Vein
    The Big Vein
    The Big Vein refers to a thick seam of bituminous coal discovered in the Georges Creek Valley of Western Maryland in the early 19th century. This coal vein became famous for its clean-burning low sulfur content that made it ideal for powering ocean steamers, river boats, locomotives, steam mills,...

  • Bowen Basin
    Bowen Basin
    The Bowen Basin contains the largest coal reserves in Australia. This major coal producing region contains one of the world's largest deposits of bituminous coal. The Basin contains much of the known Permian coal resources in Queensland including virtually all of the known mineable prime coking coal...

  • Coal assay
    Coal assay
    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.-Chemical...

  • Georges Creek Valley
    Georges Creek Valley
    Georges Creek Valley is located in Allegany County, Maryland along the George's Creek. The valley is rich in wide veins of coal, known historically as the "The Big Vein." Coal was once extracted by deep mines but is only mined today through surface mining...

  • Lignite
    Lignite
    Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

    , anthracite and graphite
    Graphite
    The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...

  • List of CO2 emitted per million Btu of energy from various fuels
  • List of rock types
  • Maceral
    Maceral
    A maceral is a component of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite and liptinite.- Inertinite :...

    s
  • Smithing coal
  • Vitrinite
    Vitrinite
    Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass . It is derived from the cell-wall material or...

    including vitrinite reflectance

External links

  • http://chemed.chem.purdue.edu/genchem/topicreview/bp/1organic/coal.html
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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