Raw coke
Eighteenth-century coke blast furnaces in Shropshire, England

Metallurgical coal or coking coal[1] is a grade of coal that can be used to produce good-quality coke. Coke is an essential fuel and reactant in the blast furnace process for primary steelmaking.[2][3][4] The demand for metallurgical coal is highly coupled to the demand for steel. Primary steelmaking companies often have a division that produces coal for coking, to ensure a stable and low-cost supply.[5]

Metallurgical coal comes mainly from Canada, the United States, and Australia,[1] with Australia exporting 58% of seaborne trade, mostly going to China.[6] In the United States, the electric power sector used "93% of total U.S. coal consumption between 2007 and 2018"; only 7% of the total was metallurgical coal and coal for other uses such as heating.[7]

Characteristics

Metallurgical coal is low in ash, moisture, sulfur and phosphorus content, and its rank is usually bituminous. Some grades of anthracite coal are used for sintering, pulverized coal injection, direct blast furnace charge, pelletizing, and in production of ferro-alloys, silicon-manganese, calcium-carbide and silicon-carbide. Metallurgical coal produces strong, low-density coke when it is heated in a low-oxygen environment. On heating, the coal softens, and volatile components evaporate and escape through pores in the mass. During coking, the material swells and increases in volume.

The coking ability of coal is related to its physical properties such as its rank, but laboratory testing is required to completely evaluate the coking ability of a coal. The strength and density of coke are particularly important when it is used in a blast furnace, as the coke supports part of the ore and flux burden inside the furnace. Metallurgical coal contrasts with thermal coal, which does not produce coke when heated. Because of their different end-uses, prices for the two types of coal are usually quite different.

The suitability of coal for conversion to coke is also referred to as the caking ability.[8]

Types

There are several types of metallurgical coal:[9][10][11]

See also

References

  1. ^ a b Paula Baker (2013-06-10). "The Coal Facts: thermal coal vs. metallurgical coal". Global News. Archived from the original on 2013-06-13.
  2. ^ "Coking-Steel Production Alternatives".
  3. ^ "How Steel Is Produced".
  4. ^ "Coke Production for Blast Furnace Ironmaking". Archived from the original on 2017-02-08. Retrieved 2017-03-05.
  5. ^ Reed Moyer, Competition in the Midwestern Coal Industry, Harvard University Press, 1964 ISBN 0674154002, page 56, pages 85-86
  6. ^ Uren, David (14 September 2021). "China's Ban on Australian Coal Reshapes Key Dry Bulk Market". The Maritime Executive.
  7. ^ "U.S. coal consumption in 2018 expected to be the lowest in 39 years - Today in Energy - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2019-01-25.
  8. ^ "What is Metallurgical Coal".
  9. ^ Bell, Terence (2017-05-05). "How Is Metallurgical Coal—Coking Coal—Used?". The Balance.
  10. ^ Satyendra Kumar Sarna (2018-09-25). "Metallurgical Coal". IspatGuru. Retrieved 2019-10-05.
  11. ^ "Different types of Coal". underground COAL. Retrieved 2019-10-05.
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