Bituminous coalorblack coalis a relatively softcoalcontaining a tarlike substance calledbitumen. It is of higher quality thanlignite coalbut of poorer quality thananthracite. 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 theseams. These distinctive sequences, which are classified according to either "dull, bright-banded" or "bright, dull-banded", is how bituminous coals are stratigraphically identified.Bituminous coal is an organic sedimentary rock formed bydiageneticand sub metamorphic compression ofpeatbog material. Its primary constituents aremacerals:vitrinite, andliptinite. The carbon content of bituminous coal is around 60-80%; the rest is composed of water, air, hydrogen, andsulphur, which have not been driven off from themacerals. Bank density is approximately 1346kg/m (84lb/ft). Bulk density typically runs to 833kg/m (52lb/ft). The heat content of bituminous coal ranges from 24 to 35 MJ/kg (21 million to 30 millionBTUpershort ton) on a moist, mineral-matter-free basis.Within thecoal miningindustry, this type of coal is known for releasing the largest amounts offiredamp, a dangerous mixture of gases that can cause underground explosions. Extraction of bituminous coal demands the highest safety procedures involving attentive gas monitoring, good ventilation and vigilant site management.Contents[hide] 1Uses 1.1Smithing coal 1.2Cannel coal 1.3Coking coal 2Bituminous coal by geologic period 2.1Cretaceous coals 2.2Carboniferous coals 2.3Permian coals 2.4Triassic coals 2.5Jurassic coals 3See also 4References 5External linksUses[edit]Bituminous coals are graded according to vitrinite reflectance, moisture content,volatilecontent, plasticity and ash content. Generally, the highest value bituminous coals have a specific grade ofplasticity, volatility and low ash content, especially with lowcarbonate,phosphorus, andsulphur.Plasticityis vital forcokingas 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 damaging element in steel making.Coking coalis best if it has a very narrow range of volatility and plasticity. This is measured by thefree swelling indextest. 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, sulphur, and carbonate coals are prized for power generation because they do not produce much boilerslagand they do not require as much effort to scrub theflue gasesto remove particulate matter. Carbonates are deleterious as they readily stick to the boiler apparatus. Sulphide contents are also deleterious in some fashion as this sulphur is emitted and can formsmog,acid rainand haze pollution. Again, scrubbers on the flue gases aim to eliminate particulate and sulphur emissions.Smithing coal[edit]Smithing coal is a type of high quality bituminous coal ideally suited for use in a coalforge. It is as free fromash,sulphur, and other impurities as possible.[1]The constituents of the coal should be as follows:[2]ConstituentPercentage

SulphurNot over 1%

AshNot over 7%

CarbonNot less than 70%

MoistureNot over 12%

Cannel coal[edit]Cannel coalis a coal which ignites easily producing a bright flame. The name may derive from northern English pronunciation ofcandle coal. It contains a high volatile content, is non-coking and was a source forcoal oilinWest Virginiaduring the mid-1800s.[3]While the use of Cannel has greatly diminished over the past century, it is still valued by artists for its ability to be carved and polished into sculptures and jewelry.[citation needed]Coking coal[edit]When used for many industrial processes, bituminous coal must first be"coked"to remove volatile components. Coking is achieved by heating the coal in the absence of oxygen, which drives off volatilehydrocarbonssuch aspropane,benzeneand other aromatic hydrocarbons, and some sulphur gases. This also drives off a considerable amount of the contained water of the bituminous coal.Coking coal is used in the manufacture ofsteel, 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[edit]Bituminous coal in the United States is between 100 to 300 million years old.[4]Cretaceous coals[edit]In the United States, Cretaceous bituminous coals occur in Wyoming, Colorado and New Mexico.[5][6]In Canada, theWestern Canada Sedimentary BasinofAlbertaandBritish Columbiahosts major deposits of bituminous coal that formed in swamps along the western margin of theWestern Interior Seaway. They range in age from latestJurassicor earliestCretaceousin theMist Mountain Formation, toLate Cretaceousin theGates Formation.[7]The Intermontane and Insular Coalfields of British Columbia also contain deposits of Cretaceous bituminous coal.[8]Carboniferous coals[edit]MuchNorth Americancoal was created in subsiding areas adjacent to theAppalachian Mountainsduring thePennsylvaniansubperiod. 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 ofpeat(the precursor to coal) that were buried faster than they could decay.Bituminous coal is mined in theAppalachianregion, primarily for power generation.Miningis done via both surface and underground mines.Pocahontas bituminous coalat one time fueled half the world's navies and today stokes steel mills and power plants all over the globe.Permian coals[edit]The second largest deposits of the world's bituminous coal are contained within Permian strata inRussia. Australian deposits in theBowen BasininQueensland, theSydney BasinandPerthBasin 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 intooil.Triassic coals[edit]Coals ofTriassicage are known from the Clarence-Moreton andIpswich Basins, nearIpswich, Australiaand 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[edit]Extensive but low-value coals of Jurassic age extend through theSurat BasininAustralia, formed in an intracratonic sag basin, and contain evidence ofdinosauractivity in the numerous ash plies. These coals are exploited inQueenslandfrom theWalloon Coal Measures, which are up to 15m thick of sub-bituminous to bituminous coals suited for coking, steam-raising and oil cracking.