{{Short description|Waste from coal mining}} {{Use dmy dates|date=February 2025}} thumb|Coal waste in Pennsylvania '''Coal refuse''', also known as '''coal waste''', '''rock''', '''slag''', '''coal tailings''', '''waste material''', '''rock bank''', '''culm''', '''boney''', or '''gob''',<!---all of these names should be separately cited in the body. Moved citation that does not cite them all.---> is the material left over from coal mining, usually as tailings piles or spoil tips'''.''' For every tonne of hard coal generated by mining, {{cvt|400|kg}} of waste material remains, which includes some lost coal that is partially economically recoverable.<ref>{{cite book |last1=Fecko |first1=P. |last2=Tora |first2=B. |last3=Tod |first3=M. |date=31 October 2013 |chapter=Coal waste: Handling, pollution impacts and utilization |language=en |pages=63–84 |doi=10.1533/9781782421177.1.63 |editor-last=Osborne |editor-first=Dave |title=The coal handbook: Towards cleaner production |volume=2 |publication-place=Oxford, UK |publisher=Woodhead Publishing |isbn=978-1-78242-116-0}}</ref> Coal refuse is distinct from the byproducts of burning coal, such as fly ash.
thumb|Coal spoil stones Piles of coal refuse can have significant negative environmental consequences, including the leaching of iron, manganese, and aluminum residues into waterways and acid mine drainage.<ref name=":0">{{Cite web |title=Waste Coal {{!}} Energy Justice Network |url=http://www.energyjustice.net/coal/wastecoal |access-date=2020-08-02 |website=www.energyjustice.net}}</ref> The runoff can create both surface and groundwater contamination.<ref>{{cite journal |last1=Kowalska |first1=Arlena |last2=Kondracka |first2=Marta |last3=Mendecki |first3=Maciej Jan |title=VLF mapping and resistivity imaging of contaminated quaternary formations near 'Panewniki' coal waste disposal (Southern Poland) |language=en |journal=Acta Geodynamica et Geromaterialia |volume=9 |issue=4 |date=2012 |pages=473–480 |publisher=Czech Academy of Sciences, Institute of Rock Structure and Mechanics |id={{ResearchGatePub|259218387}} |url=https://www.irsm.cas.cz/materialy/acta_content/2012_04/5.Kowalska.pdf}}</ref> The piles also create a fire hazard, with the potential to spontaneously ignite. Because most coal refuse harbors toxic components, it is not easily reclaimed by replanting with plants like beach grasses.<ref name=":3">{{Cite web |last=Patel |first=Sonal |date=2016-07-01 |title=The Coal Refuse Dilemma: Burning Coal for Environmental Benefits |url=https://www.powermag.com/coal-refuse-dilemma-burning-coal-environmental-benefits/ |access-date=2020-08-02 |website=Power Magazine |language=en}}</ref><ref>{{Cite journal |last1=Dove |first1=D. |last2=Daniels |first2=W. |last3=Parrish |first3=D. |date=1990 |title=Importance of Indigenous VAM Fungi for the Reclamation of Coal Refuse Piles |journal=Journal American Society of Mining and Reclamation |volume=1990 |issue=1 |pages=463–468 |doi=10.21000/jasmr90010463 |issn=2328-8744 |doi-access=free | url=https://www.asrs.us/DOI/Proceedings/1990v1/JASMR90010463-Dove.pdf}}</ref>
Gob has about four times as much toxic mercury and more sulfur than typical coal.<ref name=":0" /> Culm is the term for waste anthracite coal.<ref name=":0" />
== Disposal == The first step to reclaiming land occupied by coal refuse piles is to remove the refuse matter.<ref name="2021Power">{{cite web |last1=Patel |first1=Sonal |title=The Remarkable Responsibility of Coal Refuse Power |url=https://www.powermag.com/the-remarkable-responsibility-of-coal-refuse-power/ |website=Power Magazine |date=2 August 2021}}</ref>
=== As fuel === Where economically viable, some coal miners try to reprocess these wastes. This may include complex reprocessing in more industrialized economies,<ref>{{cite book |last1=Woodruff |first1=D. |last2=Macnamara |first2=L. |date=31 October 2013 |chapter=Treatment of coal tailings |language=en |pages=529–559 |doi=10.1533/9780857097309.2.529 |editor-last=Osborne |editor-first=Dave |title=The coal handbook: Towards cleaner production |volume=2 |publication-place=Oxford, UK |publisher=Woodhead Publishing |isbn=978-0-85709-422-3}}</ref> such as fluidized bed combustion in power plants.<ref name=":3" /> In less industrialized systems, manual sorting may be employed. For example, in the Jharia coalfield in eastern India, a large cohort of "coal cycle wallahs" manually sort mine tailings with their families, and then transport the salvaged coal on bicycles more than {{cvt|60|km|mi}} to market.<ref>{{Cite magazine | last=Pearce | first=Fred | date=15 March 2016 | title=The human cost of India's push to produce more coal |url=https://e360.yale.edu/features/on_burning_ground_human_cost_indias_push_produce_more_coal |access-date=2020-08-02 |magazine=Yale Environment 360 |publisher= Yale School of the Environment|language=en|oclc=427432124}}</ref><ref name=":1">{{Cite book |last1=Pai |first1=Sandeep |url=https://books.google.com/books?id=-iMZtQEACAAJ&q=Total+Transition:+The+Human+Side+of+the+Renewable+Energy+Revolution |title=Total Transition: The Human Side of the Renewable Energy Revolution |last2=Carr-Wilson |first2=Savannah |date=2018 |publisher=Rocky Mountain Books |isbn=978-1-77160-248-8 |language=en}}</ref>
==== Handling of combustion products ==== The burning of waste coal typically produces more environmental toxins than higher energy coals.<ref name=":0" /> Modern fluidized bed combustion with limestone for acid gas control can lower toxin emissions to acceptable levels,{{efn|Burning of waste coal also produces more {{CO2}} than higher-grade coals. Current (2013) technology does not usefully mitigate this difference.}} concentrating the toxicity into waste ash. For every 100 tons of coal waste burned, 85 tons of waste ash (more toxic versions of fly ash and bottom ash) are created.<ref name=":3" /> However, this ash is more stable than the waste and may simply be re-compacted into the mine site with less risk of leaching. It can also be used to neutralize acidic mine discharge.<ref name="2021Power"/>
The waste ash from burning coal waste was approved as a source of fly ash by the West Virginia Department of Highways in 2019.<ref name="2021Power"/>
=== Other uses === There have been some attempts to use non-flammable coal waste in concrete production, similar to the use of fly ash.<ref>{{cite journal |last1=Caneda-Martínez |first1=Laura |last2=Frías |first2=Moisés |last3=Medina |first3=César |last4=de Rojas |first4=Mª Isabel Sánchez |last5=Rebolledo |first5=Nuria |last6=Sánchez |first6=Javier |date=30 November 2018 |title=Evaluation of chloride transport in blended cement mortars containing coal mining waste |journal=Construction and Building Materials |volume=190 |pages=200–210 |doi=10.1016/j.conbuildmat.2018.09.158 |id={{Gale|A569157868}}}}</ref>
== By geography ==
=== United States === In the United States, most waste coal piles accumulated from 1900 to 1970 when processing techniques were less sophisticated.<ref>{{Cite web |title=Waste Coal {{!}} Energy Justice Network |url=http://www.energyjustice.net/coal/wastecoal |access-date=2020-08-02 |website=www.energyjustice.net}}</ref> The US has a longstanding inspection program of these refuse piles.<ref>{{Cite book |author=Mining Enforcement and Safety Administration |url=https://books.google.com/books?id=CT-K0ZHOebkC |title=Coal Refuse Inspection Manual |date=April 1976 |publisher=Author |language=en}}</ref> In Pennsylvania alone, there are over 770 such piles identified.<ref>{{Cite web |title=What is coal refuse |url=https://arippa.org/what-is-coal-refuse/ |access-date=2020-08-02 |website=arippa.org |language=en | publication-place=Camp Hill, Pennsylvania | publisher=Appalachian Region Independent Power Producers Association }}</ref> There are at least 18 coal waste burning plants in the United States,<ref name=":2">{{Cite web |title=Coal Waste {{!}} Waste Coal Ash {{!}} Byproduct Of Coal Processing Operations |url=https://www.rpmsolve.com/coal-waste |access-date=2020-08-02 |website=www.rpmsolve.com}}</ref> mostly in Pennsylvania.
The Grant Town Power Project in West Virginia burns 530,000 tons of coal refuse annually, allowing the reclamation of 30 acres of land annually.<ref name="2021Power"/> Still, there's criticism regarding the plant's negative profitability and its greenhouse gas emissions from burning coal. The plant has controversially proposed pivoting to cryptocurrency mining for funding.<ref>{{cite web |last1=Waldman |first1=Scott |title=A coal plant fights to stay open. It could enrich Manchin |url=https://www.eenews.net/articles/a-coal-plant-fights-to-stay-open-it-could-enrich-manchin/ |website=E&E News |date=17 November 2021}}</ref> Wider replacement of cement by its fly ash should bring down its carbon footprint.<ref name="2021Power"/>
== Etymology == {{See also|List of common false etymologies of English words}} {{Wiktionary|boney|culm|goaf|gob}} The word ''gob'' or ''goaf'' referring to coal waste is of uncertain origin but goes back over 200 years, long before a false etymology as a backronym for "garbage of bituminous" was humorously invented to "explain" it.<ref>{{Cite news |last1=Flavelle |first1=Christopher |last2=Tate |first2=Julie |last3=Schaff |first3=Erin |date=2022-03-27 |title=How Joe Manchin Aided Coal, and Earned Millions |language=en-US |work=The New York Times |url=https://www.nytimes.com/2022/03/27/climate/manchin-coal-climate-conflicts.html |access-date=2022-03-28 |issn=0362-4331}}</ref>{{Verify source|date=August 2025}}<ref>For an early attestation, see eg. {{cite EB9 | vb= | wstitle=Coal | quote=The space from which the entire quantity of coal has been removed is known in different districts as the 'goaf', 'gob', or 'waste'. | volume=VI | page=64}}</ref>
== Disasters == In the 1966 Aberfan disaster in Wales, a colliery spoil tip collapsed, engulfing a school and killing 116 children and 28 adults. Other accidents involving coal waste include the Martin County coal slurry spill (US, 2000), the Kingston Fossil Plant coal fly ash slurry spill (US, 2008), and the Obed Mountain coal mine spill (Canada, 2013).
== Notes == {{Notelist}}
== References == {{Reflist}}
{{Coal}} {{Authority control}}
Category:Coal mining Category:Mining waste Category:By-products