Coal refuse (also described as coal waste, rock, slag, coal tailings, waste material, rock bank, culm, boney, or gob[1]) is the material left over from coal mining, usually as tailings piles or spoil tips. For every tonne of hard coal generated by mining, 400 kg (880 lb) of waste material remains, which includes some lost coal that is partially economically recoverable.[2] Coal refuse is distinct from the byproducts of burning coal, such as fly ash.

Coal waste in Pennsylvania
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.[3] The runoff can create both surface and groundwater contamination.[4] 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.[5][6]

Gob (short for "garbage of bituminous"[7]) has about four times as much toxic mercury and more sulfur than typical coal.[1] Culm is the term for waste anthracite coal.[1]

Disposal edit

The first step to reclaiming land occupied by coal refuse piles is to remove the refuse matter.[8]

As fuel edit

Where economically viable, some coal miners try to reprocess these wastes. In more industrialized economies, this may include complex reprocessing,[9] such as fluidized bed combustion in power plants.[5] 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 60 kilometers to market.[10][11]

The burning of waste coal typically produces more environmental toxins than higher energy coals.[1] Modern fluidized bed combustion with limestone for acid gas control can lower toxin emissions to acceptable levels,[a] 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.[5] Fortunately, 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.[8]

Other uses edit

There have been some attempts to use non-flammable coal waste in concrete production, similar to the use of fly ash.[12] The waste ash from burning of coal waste is approved as a source of fly ash by the West Virginia Department of Highways in 2019.[8]

By geography edit

United States edit

In the United States, most waste coal piles accumulated from 1900 to 1970 when processing techniques were less sophisticated.[13] The US has a longstanding inspection program of these refuse piles.[14] In Pennsylvania alone, there are over 770 such piles identified.[15] There are at least 18 coal waste burning plants in the United States,[16] mostly in Pennsylvania.

The Grant Town Power Project in West Virginia burns 530,000 tons of coal refuse annually, allowing the reclaimation of 30 acres of land per year.[8] 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.[17] Wider replacement of cement by its fly ash should bring down its carbon footprint.[8]

Disasters edit

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) and the Obed Mountain coal mine spill (Canada, 2013).

References edit

  1. ^ Burning of waste coal also produces more CO2 than higher-grade coals. Current (2013) technology does not usefully mitigate this difference.
  1. ^ a b c d "Waste Coal | Energy Justice Network". Retrieved 2 August 2020.
  2. ^ Fecko, P.; Tora, B.; Tod, M. (1 January 2013), Osborne, Dave (ed.), "3 - Coal waste: handling, pollution impacts and utilization", The Coal Handbook: Towards Cleaner Production, Woodhead Publishing Series in Energy, vol. 2, Woodhead Publishing, pp. 63–84, ISBN 978-1-78242-116-0, retrieved 2 August 2020
  3. ^ "Waste Coal | Energy Justice Network". Retrieved 2 August 2020.
  4. ^ Kowalska, Arlena, et al., "VLF mapping and resistivity imaging of contaminated quaternary formations near to 'Panewniki' coal waste disposal (Southern Poland)." Acta Geodynamica et Geromaterialia, vol. 9, no. 4, 2012, p. 473+. Gale Academic OneFile, Accessed 7 Aug. 2020.
  5. ^ a b c POWER (1 July 2016). "The Coal Refuse Dilemma: Burning Coal for Environmental Benefits". POWER Magazine. Retrieved 2 August 2020.
  6. ^ Dove, D.; Daniels, W.; Parrish, D. (1990). "Importance of Indigenous VAM Fungi for the Reclamation of Coal Refuse Piles". Journal American Society of Mining and Reclamation. 1990 (1): 463–468. doi:10.21000/jasmr90010463. ISSN 2328-8744.
  7. ^ Flavelle, Christopher; Tate, Julie; Schaff, Erin (27 March 2022). "How Joe Manchin Aided Coal, and Earned Millions". The New York Times. ISSN 0362-4331. Retrieved 28 March 2022.
  8. ^ a b c d e Patel, Sonal (2 August 2021). "The Remarkable Responsibility of Coal Refuse Power". POWER Magazine.
  9. ^ Woodruff, D.; Macnamara, L. (1 January 2013), Osborne, Dave (ed.), "16 - Treatment of coal tailings", The Coal Handbook: Towards Cleaner Production, Woodhead Publishing Series in Energy, vol. 1, Woodhead Publishing, pp. 529–559, ISBN 978-0-85709-422-3, retrieved 2 August 2020
  10. ^ "The Human Cost Of India's Push to Produce More Coal". Yale E360. Retrieved 2 August 2020.
  11. ^ Pai, Sandeep; Carr-Wilson, Savannah (2018). Total Transition: The Human Side of the Renewable Energy Revolution. Rocky Mountain Books. ISBN 978-1-77160-248-8.
  12. ^ Caneda-Martmez, Laura, et al. "Evaluation of chloride transport in blended cement mortars containing coal mining waste". Construction and Building Materials, vol. 190, 30 Nov. 2018, p. 200+. Gale General OneFile, Accessed 7 August 2020.
  13. ^ "Waste Coal | Energy Justice Network". Retrieved 2 August 2020.
  14. ^ Administration, United States Mining Enforcement and Safety (1976). Coal Refuse Inspection Manual. U.S. Department of the Interior, Mining Enforcement and Safety Administration.
  15. ^ "What Is Coal Refuse". ARIPPA. Retrieved 2 August 2020.
  16. ^ "Coal Waste | Waste Coal Ash | Byproduct Of Coal Processing Operations". Retrieved 2 August 2020.
  17. ^ Waldman, Scott (17 November 2021). "A coal plant fights to stay open. It could enrich Manchin". E&E News.