Metallurgical coal

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Raw coke Koks Brennstoff.jpg
Raw coke
Eighteenth-century coke blast furnaces in Shropshire, England Blast Furnaces at Blists Hill.jpg
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]

Contents

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

Related Research Articles

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<span class="mw-page-title-main">Coke (fuel)</span> Hard fuel containing mostly carbon

Coke is a grey, hard, and porous coal-based fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.

<span class="mw-page-title-main">Cast iron</span> Iron-carbon alloys with a carbon content more than 2% and silicon content between 1 to 3%

Cast iron is a class of iron–carbon alloys with a carbon content more than 2% and silicon content around 1-3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its carbon appears: white cast iron has its carbon combined into an iron carbide named cementite, which is very hard, but brittle, as it allows cracks to pass straight through; grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.

<span class="mw-page-title-main">Anthracite</span> Hard, compact variety of coal

Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.

<span class="mw-page-title-main">Steelmaking</span> Process for producing steel from iron ore and scrap

Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon and vanadium are added to produce different grades of steel.

<span class="mw-page-title-main">Blast furnace</span> Type of furnace used for smelting to produce industrial metals

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being supplied above atmospheric pressure.

<span class="mw-page-title-main">Induction heating</span> Process of heating an electrically conducting object by electromagnetic induction

Induction heating is the process of heating electrically conductive materials, namely metals or semi-conductors, by electromagnetic induction, through heat transfer passing through an inductor that creates an electromagnetic field within the coil to heat up and possibly melt steel, copper, brass, graphite, gold, silver, aluminum, or carbide.

<span class="mw-page-title-main">Industrial processes</span> Process of producing goods

Industrial processes are procedures involving chemical, physical, electrical, or mechanical steps to aid in the manufacturing of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry.

<span class="mw-page-title-main">Refractory</span> Materials resistant to decomposition under high temperatures

In materials science, a refractory is a material that is resistant to decomposition by heat or chemical attack that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compounds that may be porous or non-porous, and their crystallinity varies widely: they may be crystalline, polycrystalline, amorphous, or composite. They are typically composed of oxides, carbides or nitrides of the following elements: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium. Many refractories are ceramics, but some such as graphite are not, and some ceramics such as clay pottery are not considered refractory. Refractories are distinguished from the refractory metals, which are elemental metals and their alloys that have high melting temperatures.

<span class="mw-page-title-main">Heating element</span> Device that converts electricity into heat

A heating element converts electrical energy into heat through the process of Joule heating. Electric current running through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is independent of the direction of current.

<span class="mw-page-title-main">Electric arc furnace</span> Type of furnace

An electric arc furnace (EAF) is a furnace that heats material by means of an electric arc.

Ferroalloy refers to various alloys of iron with a high proportion of one or more other elements such as manganese (Mn), aluminium (Al), or silicon (Si). They are used in the production of steels and alloys. The alloys impart distinctive qualities to steel and cast iron or serve important functions during production and are, therefore, closely associated with the iron and steel industry, the leading consumer of ferroalloys. The leading producers of ferroalloys in 2014 were China, South Africa, India, Russia and Kazakhstan, which accounted for 84% of the world production. World production of ferroalloys was estimated as 52.8 million tonnes in 2015.

Coal analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.

<span class="mw-page-title-main">Hot blast</span> Metallurgical preheating of air

Hot blast refers to the preheating of air blown into a blast furnace or other metallurgical process. As this considerably reduced the fuel consumed, hot blast was one of the most important technologies developed during the Industrial Revolution. Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces.

<span class="mw-page-title-main">Fireplace insert</span>

Invented in 1896 by Joab R. Donaldson of Oliphant Furnace, Pennsylvania, US, the fireplace insert is a device that can be inserted into an existing masonry or prefabricated wood fireplace. Joab was a 59-year-old coal miner and father of 14 at the time of his patent. He came upon the idea as a means of using coke and incorporating the use of an electric blower to improve the efficiency. The selection of coke and coal tailings as a primary fuel enabled low-income families to heat their Appalachian homes with small-size coal that they could easily dig for themselves in their own backyards.

<span class="mw-page-title-main">Cupola furnace</span> Small blast furnace for melting scrap iron without reduction reactions

A cupola or cupola furnace is a melting device used in foundries that can be used to melt cast iron, Ni-resist iron and some bronzes. The cupola can be made almost any practical size. The size of a cupola is expressed in diameters and can range from 1.5 to 13 feet. The overall shape is cylindrical and the equipment is arranged vertically, usually supported by four legs. The overall look is similar to a large smokestack.

Pulverized coal injection is a method for improving the performance of a blast furnace.

<span class="mw-page-title-main">Acheson process</span>

The Acheson process was invented by Edward Goodrich Acheson to synthesize silicon carbide (SiC) and graphite.

Adrien C. B. Chenot was a French engineer best known for his inventions in metallurgy as well as his research on manufactured gases. He is notably the inventor of one of the first modern methods of direct reduction of iron ore, based on the use of coal reacting with the ore in retorts. He exhibited the first samples of pre-reduced iron ore at the Lisbon Universal Exhibition of 1849, and was awarded the "Grandes Medailles d'Or" at the Paris Universal Exposition of 1855.

<span class="mw-page-title-main">Krupp–Renn Process</span> A direct reduction steelmaking process used from the 1930s to the 1970s.

The Krupp–Renn process was a direct reduction steelmaking process used from the 1930s to the 1970s. It used a rotary furnace and was one of the few technically and commercially successful direct reduction processes in the world, acting as an alternative to blast furnaces due to their coke consumption. The Krupp-Renn process consumed mainly hard coal and had the unique characteristic of partially melting the charge. This method is beneficial for processing low-quality or non-melting ores, as their waste material forms a protective layer that can be easily separated from the iron. It generates Luppen, nodules of pre-reduced iron ore, which can be easily melted down.

References

  1. 1 2 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.