Editing Bituminous coal (section)

==Properties==
[[File:Bituminous coal (Pikeville Formation, Middle Pennsylvanian; Rt. 15 roadcut north of Jackson, Kentucky, USA) 1.jpg|thumb|Bituminous coal (Pikeville Formation, Middle Pennsylvanian, Kentucky, USA)]]
Bituminous coal is a particular ''[[Coal rank|rank]]'' of [[coal]], as determined by the amount and type of [[carbon]] present in the coal and the amount of energy it can produce when burned.<ref name="EIA Coal Explained">{{cite web | url=https://www.eia.gov/energyexplained/index.cfm?page=coal_home | title=Coal Explained | publisher=[[US Energy Information Administration]] | work=Energy Explained | date=21 April 2017 | access-date=13 November 2017 | url-status=live | archive-url=https://web.archive.org/web/20171208115825/https://www.eia.gov/energyexplained/index.cfm?page=coal_home | archive-date=8 December 2017}}</ref> It is higher in rank than [[sub-bituminous coal]] but lower in rank than [[anthracite]].<ref name=Jackson/> Bituminous coal is the most abundant rank of coal.<ref name=Jackson/><ref name="EIA Coal Explained"/>

Coal rank is based on several characteristics of the coal. The ''fixed carbon content'' refers to the percentage of the coal that is neither moisture, nor ash, nor volatile matter. When evaluated on a dry, mineral-matter-free basis, the fixed carbon content is the fraction of the coal that is not volatile organic matter.<ref name=UKFixedCarbon>{{cite web |title=Fixed carbon in coal (part of proximate analysis) |url=http://www.uky.edu/KGS/coal/coal-analyses-fixed-carbon.php |website=Kentucky Geological Survey: Earth Resources -- Our Common Wealth |publisher=University of Kentucky |access-date=28 November 2020}}</ref>  An ''agglomerating'' coal is a coal that softens when heated, forming a hard, gray, porous [[Coke (fuel)|coke]] that resists crushing.<ref>{{cite web |title=Glossary |url=https://www.eia.gov/tools/glossary/index.php?id=coal |publisher=U.S. Energy Information Administration |access-date=10 November 2021 |location=agglomerating character; coal analysis}}</ref> ''Vitrinite reflectance'' is a measure of how reflective a polished surface of an average particle of ''[[vitrinite]]'' in the coal is. It is determined by how much of the carbon has condensed to an [[Aromatic compound|aromatic form]] from the heat and pressure of deep burial.<ref name=UKVitriniteReflectance>{{cite web |title=Vitrinite reflectance (Ro) |url=http://www.uky.edu/KGS/coal/coal-analyses-vitrinite.php |website=Kentucky Geological Survey: Earth Resources -- Our Common Wealth |publisher=University of Kentucky |access-date=28 November 2020}}</ref>

In the United States, bituminous coal is defined as agglomerating coal yielding at least 10,500 [[Btu]]/lb (24,400 kJ/kg) of energy on combustion (on a moist, mineral-matter-free basis), with a fixed carbon content less than 86% (on a dry, mineral-matter-free basis.) Coal with a higher fixed carbon content is classified as anthracite, while agglomerating coal yielding less than 10,500 Btu/lb (24,400 kJ/kg) or nonagglomerating coal yielding less than 11,500 Btu/lb (26,700 kJ/kg) is classified as sub-bituminous coal.<ref name=Mobley2001>{{cite book |last1=Mobley |first1=R. Keith |title=Plant engineer's handbook |date=2001 |publisher=Butterworth-Heinemann |location=Boston |isbn=9780080539041 |page=21/339 |url=https://books.google.com/books?id=9YkqH5HgSgwC |access-date=10 November 2021 |chapter=Coal and ash}}</ref> In the international market, bituminous coal is defined as coal with a vitrinite reflectance between 0.5 and 1.9. Vitrinite reflectance is also routinely measured for U.S. coal as a check on its rank classification<ref name=UKBituminousCoal>{{cite web |title=Bituminous coal |url=http://www.uky.edu/KGS/coal/coal-bituminous.php |website=Kentucky Geological Survey: Earth Resources -- Our Common Wealth |publisher=University of Kentucky |access-date=28 November 2020}}</ref>

Bituminous coal is dark brown to black,<ref name=Jackson>{{cite book |editor1-last=Jackson |editor1-first=Julia A. |title=Glossary of geology. |date=1997 |publisher=American Geological Institute |location=Alexandria, Virginia |isbn=0922152349 |edition=Fourth |chapter=bituminous coal}}</ref> hard,<ref name=Boggs231>{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0131547283 |edition=4th |page=231}}</ref> but [[friable]].<ref>{{cite book |last1=Blatt |first1=Harvey |last2=Middleton |first2=Gerard |last3=Murray |first3=Raymond |title=Origin of sedimentary rocks |date=1980 |publisher=Prentice-Hall |location=Englewood Cliffs, N.J. |isbn=0136427103 |edition=2d |pages=333–334}}</ref> It is commonly composed of thin bands of alternating bright and dull material.<ref name=Boggs231/> Though bituminous coal varies in its chemical composition, a typical composition is about 84.4% carbon, 5.4% hydrogen, 6.7% oxygen, 1.7% nitrogen, and 1.8% sulfur, on a weight basis.<ref name=Perry>{{cite book |editor1-last=Robert Perry |editor2-last=Cecil Chilton |chapter=Chapter 9: Heat Generation, Transport, and Storage|first=William|last=Reid|title=Chemical Engineers' Handbook |date=1973 |edition=5}}</ref> Its bank density (the density of a coal seam prior to breaking up during mining) is about 1346&nbsp;kg/m<sup>3</sup> (84&nbsp;lb/ft<sup>3</sup>) while the [[bulk density]] of extracted coal is up to 833&nbsp;kg/m<sup>3</sup> (52&nbsp;lb/ft<sup>3</sup>).<ref name="BMT">{{cite web |title=Coal and Coke |url=https://cargohandbook.com/Coal_and_Coke |website=CargoHandbook.com |publisher=[[BMT Group]] |access-date=8 November 2021}}</ref> Bituminous coal characteristically burns with a smoky flame and softens and swells during combustion.<ref name=Allaby>{{cite book |last1=Allaby |first1=Michael |title=A dictionary of geology and earth sciences |date=2013 |publisher=Oxford University Press |location=Oxford |isbn=9780199653065 |edition=Fourth |chapter=bituminous coal}}</ref> It gets its name from this tendency to form a softened, sticky mass when heated,<ref name=UKBituminousCoal/> which reflects the presence of [[bitumen]] (mineral tar) in the coal.<ref name=UKBituminousCoal/>

Though almost all agglomerating coal is of bituminous rank, some bituminous coal is not agglomerating.<ref name=Mobley2001/> Non-agglomerating bituminous coal includes [[cannel coal]] and [[boghead coal]]. These are nonbanded and nonreflective, and break with a conchoidal fracture. Both are ''sapropelic'', in contrast with most bituminous coal, which is ''humic'' (composed of decayed woody tissue of plants). Cannel coal is composed mostly of plant spores, while boghead coal is composed mostly of nonspore algal remains.{{sfn|Boggs|2006|pp=231-232}}<ref>{{Cite web|url=https://www.mindat.org/min-49324.html|title=Sapropelic coal series: Mineral information, data and localities.}}</ref>

===Subranks===
In the United States, bituminous coal is further divided into subranks based on its heating value and fixed carbon content.

{|class=wikitable
|+ASTM Bituminous Coal Classification<ref>Dave Osborne (ed), ''The Coal Handbook: Towards Cleaner Production: Volume 1: Coal Production'' Elsevier, 2013
{{ISBN|085709730X}}, table 2.5 page 47</ref>
!Class
!Group
!Fixed Carbon % <br> Dry, mineral free
!Volatile Matter %<br> Dry, mineral free
![[Heating Value]] MJ/kg <br> Moist, mineral free

|-
|rowspan=5|Bituminous||Low Volatile||78–86||14–22||  &nbsp;
|-
||Medium Volatile||69–78||22–31||  &nbsp;
|-
||High Volatile A||<69||>31||>32.6  
|-
||High Volatile B||&nbsp; ||&nbsp; ||30.2–32.6  
|-
||High Volatile C||&nbsp;  ||&nbsp; ||26.7–30.2

|}

Thus bituminous coal is divided into high-, medium-, and low-volatile categories based on fixed carbon content, and high-volatile bituminous coal is further subdivided by energy content.

ISO classification of bituminous coal is based on vitrinite reflectance.<ref name=UKVitriniteReflectance/> This classification divides medium rank coal (approximately equivalent to bituminous coal) into four subranks. In order of increasing rank, these are:{{sfn|Keijers|2012|pp=28, 31}}
* Medium D: Vitrinite reflectance of 0.5 to 0.6. Corresponds approximately to ASTM high volatile C bituminous or sub-bituminous A.
* Medium C: Vitrinite reflectance of 0.6 to 1.0. Corresponds approximately to ASTM high volatile C to high volatile B bituminous.
* Medium B : Vitrinite reflectance of 1.0 to 1.4. Corresponds approximately to ASTM high volatile A to medium volatile bituminous.
* Medium A: Vitrinite reflectance of 1.4 to 2.0. Corresponds approximately to ASTM low volatile bituminous.