Charcoal Packaging of charcoal for export in Namibia
Charcoal is a lightweight blackcarbon residue produced by strongly heatingwood (or otheranimal andplant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of thispyrolysis process, called charcoal burning, often by forming acharcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply ofoxygen. The material can also be heated in a closedretort. Modern charcoalbriquettes used for outdoor cooking may contain many other additives, e.g.coal.
The history of wood charcoal production spans ancient times, rooted in the abundance of wood in various regions. The process typically involves stacking wood billets to form a conical pile, allowing air to enter through openings at the bottom, and igniting the pile gradually. Charcoal burners, skilled professionals tasked with managing the delicate operation, often lived in isolation to tend their wood piles. Throughout history, the extensive production of charcoal has been a significant contributor to deforestation, particularly in regions like Central Europe. However, various management practices, such ascoppicing, aimed to maintain a steady supply of wood for charcoal production. The scarcity of easily accessible wood resources eventually led to the transition to fossil fuel equivalents like coal.
Modern methods of charcoal production involve carbonizing wood in retorts, yielding higher efficiencies compared to traditional kilning methods. The properties of charcoal depend on factors such as the material charred and the temperature of carbonization.
Charcoal finds diverse applications, including metallurgical fuel in iron and steel production, industrial fuel, cooking and heating fuel, reducing agent in chemical processes, and as a raw material in pyrotechnics. It is also utilized in cosmetics, horticulture, animal husbandry, medicine, and environmental sustainability efforts, such as carbon sequestration.
However, the production and utilization of charcoal can have adverse environmental impacts, including deforestation and emissions. Illegal and unregulated charcoal production, particularly in regions like South America and Africa, poses significant challenges to environmental conservation efforts.
Oak wood pile before the covering with soil and straw (c. 2006)An abandoned charcoal kiln near Walker, Arizona, USWood pile before covering withturf or soil, and firing it (c. 1890)
The production of wood charcoal in locations where there is an abundance of wood dates back to ancient times. It generally began with piling billets of wood on their ends to form a conical pile. Openings were left at the bottom to admitair, with a central shaft serving as aflue. The whole pile was covered with turf or moistenedclay. The firing began at the bottom of the flue, and the fire gradually spread outward and upward.
The traditional method inBritain used acharcoal pile or clamp.[1] This was essentially a pile of wooden logs (e.g. seasoned oak) leaning in a circle against a chimney. The chimney consisted of 4 wooden stakes held up by some rope. In the clamp too the logs were completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney. The logs burned slowly and transformed into charcoal over a period of 5 days. If the soil covering became torn or cracked by the fire, additional soil was placed on the cracks. Once the burn was complete, the chimney was plugged to prevent air from entering.
The true art of this production method was in managing the sufficient generation of heat, by combusting part of the wood material, and the transfer of the heat to the wood in the process of being carbonized. The operation was so delicate that it was generally left tocolliers (professional charcoal burners). They often lived alone in small huts to tend their wood piles. For example, in theHarz Mountains of Germany,charcoal burners lived in conicalhuts calledKöten which still exist today.[when?]
The success of the operation depends upon the rate of thecombustion. Under average conditions wood yields about 60% charcoal byvolume, or 25% byweight;[2] small-scale production methods often yield only about 50% by volume, while large-scale methods enabled higher yields of about 90% by the 17th century. A strong disadvantage of this production method is the huge amount of emissions that are harmful to human health and the environment (emissions of unburnt methane).[3] As a result of the partial combustion of wood material, the efficiency of the traditional method is low.
The massive production of charcoal (at its height employing hundreds of thousands, mainly in Alpine and neighbouring forests) was a major cause ofdeforestation, especially inCentral Europe.[4][when?] Complaints (as early as theStuart period) about shortages may stem fromover-exploitation or the impossibility of increasing production to match growing demand. InEngland, many woods were managed ascoppices, which were cut and regrown cyclically, so that a steady supply of charcoal was available. But the increasing scarcity of easily harvested wood was a major factor behind the switch tofossil fuel equivalents, mainlycoal andbrown coal for industrial use.
InFinland andScandinavia, the charcoal was considered the by-product of wood tar production. The best tar came frompine, thus pinewoods were cut down for tarpyrolysis. The residual charcoal was widely used as substitute formetallurgicalcoke inblast furnaces forsmelting. Tar production led to rapid local deforestation. The end of tar production at the end of the 19th century resulted in rapid re-forestation of affected areas.
Charcoal under a microscope. Different colors correspond to different relief. Only a charred skeleton remains of the wood cells after charring.
The modern process of carbonizing wood, either in small pieces or assawdust incast ironretorts, is extensively practiced where wood is scarce, and also for the recovery of valuable byproducts (wood spirit,pyroligneous acid,wood tar), which the process permits. The question of thetemperature of thecarbonization is important; according to J. Percy, wood becomes brown at 220 °C (430 °F), a deep brown-black after some time at 280 °C (540 °F), and an easily powdered mass at 310 °C (590 °F). Charcoal made at 300 °C (570 °F) is brown, soft and friable, and readily inflames at 380 °C (720 °F); made at higher temperatures it is hard and brittle, and does not fire until heated to about 700 °C (1,300 °F).[2][6]
Modern methods employ retorting technology, in which process heat is recovered from, and solely provided by, the combustion of gas released during carbonization.[7] Yields of retorting are considerably higher than those of kilning, and may reach 35%-40%.
The properties of the charcoal produced depend on the material charred. Thecharring temperature is also important. Charcoal contains varying amounts of hydrogen and oxygen as well asash and other impurities that, together with the structure, determine the properties. The approximate composition of charcoal forgunpowders is sometimes empirically described as C7H4O.[citation needed] To obtain a coal with high purity, source material should be free of non-volatile compounds.
Wood charcoal is obtained as the residue bydestructive distillation of wood such that the products are:
Binchōtan, Japanese high grade charcoal made fromubame oakOgatan, charcoal briquettes made from sawdust
Common charcoal is made from peat, coal, wood, coconut shell, or petroleum.
Sugar charcoal is obtained from the carbonization of sugar and is particularly pure. It is purified by boiling with acids to remove any mineral matter and is then burned for a long time in a current of chlorine to remove the last traces of hydrogen.[2] It was used byHenri Moissan in his early attempt to createsynthetic diamonds.[citation needed]
Activated charcoal is similar to common charcoal but is manufactured especially for medical use. To produce activated charcoal, common charcoal is heated to about 900 °C (1,700 °F) in the presence of an inert gas (usually argon or nitrogen), causing the charcoal to develop many internal spaces, or "pores", which help the activated charcoal to trap chemicals. Impurities on the surface of the charcoal are also removed during this process, greatly increasing itsadsorption capacity.
Lump charcoal is a traditional charcoal made directly fromhardwood material. It usually produces far less ash than briquettes.
Japanese charcoal has hadpyroligneous acid removed during the charcoal making; it therefore produces almost no smell or smoke when burned. The traditional charcoal of Japan is classified into three types:
Ogatan is a more recent type made from hardened sawdust.
Pillow shapedbriquettes are made by compressing charcoal, typically made from sawdust and other wood by-products, with a binder and other additives. The binder is usuallystarch. Briquettes may also includebrown coal (heat source), mineral carbon (heat source),borax,sodium nitrate (ignition aid),limestone (ash-whitening agent), rawsawdust (ignition aid), and other additives.
Sawdust briquette charcoal is made by compressing sawdust without binders or additives. It is the preferred charcoal in Taiwan, Korea, Greece, and the Middle East. It has a round hole through the center, with a hexagonal cross-section. It is used primarily for barbecue as it produces no odor, no smoke, little ash, high heat, and has a long burning time (exceeding 4 hours).
Extruded charcoal is made by extruding either raw ground wood or carbonized wood into logs without the use of a binder. The heat and pressure of the extruding process hold the charcoal together. If the extrusion is made from raw wood material, the extrudedlogs are subsequently carbonized.
Charcoal burningGrill charcoal made from coconut shell
Charcoal has been used since earliest times for a large range of purposes including art and medicine, but by far its most important use has been as a metallurgical fuel. Charcoal is the traditional fuel of a blacksmith's forge and other applications where an intense heat is required. Charcoal was also used historically as a source of blackpigment by grinding it up. In this form charcoal was important to early chemists and was a constituent of formulas for mixtures such asblack powder. Due to its highsurface area, charcoal can be used as a filter,catalyst, or adsorbent.
Charcoal burns at temperatures exceeding 1,100 degrees Celsius (2,010 degrees Fahrenheit).[9] By comparison, the melting point ofiron is approximately 1,200 to 1,550 °C (2,190 to 2,820 °F). Due to its porosity, it is sensitive to the flow of air and the heat generated can be moderated by controlling the air flow to the fire. For this reason charcoal is still widely used by blacksmiths. Charcoal has been used for the production of iron andsteel (where it also provided the necessary carbon) since at least 2000BCE, with artifacts having been found in Proto-Hittite layers atKaman-Kalehöyük.[10] Charcoal briquettes can burn up to approximately 1,260 °C (2,300 °F) with a forced air blower forge.[11]
In the 16th century, England had to pass laws to prevent the country from becoming completely denuded of trees due to production of iron.[citation needed] In the 19th century charcoal was largely replaced by coke in steel production due to cost, even though coke usually adds sulphur and sometimes other deleterious contaminants to the pig iron. Wooded metallurgical regions devoid of coal like Sweden, the Urals, or Siberia transitioned from charcoal in the early 20th century.
Prior to the Industrial Revolution, charcoal was occasionally used as a cookingfuel. It is counted as asmokeless fuel; that is, the carbon is sufficiently pure that burning it causes substantially less air pollution than burning the original uncarbonized organic material would. In the 20th century, clean-air legislation mandated smokeless fuels (mostly coke or charcoal) in many areas of Europe. In the 21st century, charcoal has been advocated as a way to improve the health of people burning raw biomass forcooking and/or heating. Modern "charcoal" briquettes, widely used for outdoor cooking, are made with charcoal but may also include coal as an energy source as well as accelerants, binders and filler.
To contain the charcoal and use it for cooking purposes, abarbecue grill may be used. A small Japanese charcoal grill is known as ashichirin. Abrazier is a container used to burn charcoal or other solid fuel.
Like many other sources of carbon, charcoal can be used for the production of varioussyngas compositions; i.e., various CO + H2 + CO2 + N2 mixtures. The syngas is typically used as fuel, including automotive propulsion, or as a chemical feedstock.
In times of scarce petroleum, automobiles and even buses have been converted to burn wood gas: a gas mixture consisting primarily of dilutingatmosphericnitrogen, but also containing combustible gasses (mostlycarbon monoxide) released by burning charcoal or wood in awood gas generator. In 1931,Tang Zhongming developed an automobile powered by charcoal, and these cars were popular in China until the 1950s, and inoccupied France duringWorld War II, where they were calledgazogènes.
Charcoal is used in the production ofblack powder, which is used extensively in the production of fireworks. It is usually ground into a fine powder, with air float grade being the finest particle size available commercially. When used in black powder compositions, it is often ball-milled with other ingredients so that they are intimately mixed together. Certain charcoals perform better when used to make black powder; these include spruce, willow, paulownia and grapevine among others.[citation needed] Charcoal produces fine dark orange/goldensparks. Usually, powder with a mesh size from 10 to 325 is used to obtain showers of golden sparks in pyrotechnic compositions.[13]
Charcoal is also incorporated in multiple cosmetic products.[14] It can be produced from regular bamboo cut into small pieces and boiled in water to remove soluble compounds.[14] Rawbamboo charcoal is obtained after drying and carbonization in an oven at elevated temperature.[14] The role of charcoal in cosmetics is based on its highly effective absorbing properties at a microscopic scale.[14]
Charcoal may be used as a source of carbon in chemical reactions. One example of this is the production ofcarbon disulphide through the reaction of sulfur vapors with hot charcoal. In that case, the wood should be charred at high temperature to reduce the residual amounts of hydrogen and oxygen that lead to side reactions.
Charcoal may beactivated to increase its effectiveness as a filter.Activated charcoal readily adsorbs a wide range of organic compounds dissolved or suspended in gases and liquids. In certain industrial processes, such as the purification of sucrose from cane sugar, impurities cause an undesirable color, which can be removed with activated charcoal. It is also used to absorbodors and toxins in gaseous solutions, as in home air purifiers and some types ofgas mask. The medical use of activated charcoal is mainly theabsorption ofpoisons.[15] Activated charcoal is available without a prescription, so it is used for a variety of health-related applications. For example, it is often used to reduce discomfort and embarrassment due to excessive gas (flatulence) in the digestive tract.[16]
Animal charcoal or bone black is the carbonaceousresidue obtained by the dry distillation of bones. It contains only about 10% carbon, the remaining being calcium andmagnesium phosphates (80%) and other inorganic material originally present in the bones. It is generally manufactured from the residues obtained in theglue andgelatin industries. Its bleaching power was applied in 1812 by Derosne for clarifyingsugarsyrup, but its use in this direction has now greatly diminished. Today it is seldom used for this purpose due to the introduction of more active and easily managed reagents, but it is still employed to some extent inlaboratory practice. The bleaching action of the charcoal in solution diminishes as it adsorbs colored contaminants, and it must be reactivated periodically by separate washing and reheating.[2] While wood charcoal effectively removes some pigments and contaminants from solutions, bone charcoal is generally more effective as an adsorption filter due to its increased porosity and surface area.[citation needed]
Four sticks of vine charcoal and four sticks of compressed charcoalTwo charcoal pencils in paper sheaths that are unwrapped as the pencil is used, and two charcoal pencils in wooden sheaths
Charcoal is used fordrawing, making roughsketches inpainting, and is one of the possible media used for making aparsemage. It usually must be preserved by the application of afixative. Artists generally utilize charcoal in four forms:
Vine charcoal is created by burning grape vines.
Willow charcoal is created by burning willow sticks.
Powdered charcoal is often used to "tone" or cover large sections of a drawing surface. Drawing over the toned areas darkens it further, but the artist can also lighten (or completely erase) within the toned area to create lighter tones.
Compressed charcoal is charcoal powder mixed with gumbinder and compressed into sticks. The amount of binder determines the hardness of the stick.[17] Compressed charcoal is used in charcoalpencils.
One additional use of charcoal was rediscovered recently[when?] forhorticulture. Although American gardeners have used charcoal for a short time,research onTerra preta soils inAmazonia has discovered the widespread use ofbiochar bypre-Columbian natives to ameliorate unproductivesoil into soil rich incarbon. The technique may find modern application, both to improve soils and as a means ofcarbon sequestration.[18]
Charcoal is mixed with feed, added tolitter, or used in the treatment ofmanure.[19] Poultry benefits from using charcoal in this manner.[20][21]
A concern that activated charcoal might be used unscrupulously to allow livestock to tolerate low quality feed contaminated withaflatoxins resulted in the Association of American Feed Control Officials banning it in 2012 from use in commercial livestock feeds.[22]
Charcoal in the form ofcharcoal biscuits was consumed in the past for gastric problems. Now it can be consumed in tablet, capsule, or powder form for digestive effects.[23] Research regarding its effectiveness is controversial.[24]
Charcoal has been used in combination withsaccharin in research to measuremucociliary transport time.[25]
Charcoal has also been incorporated intotoothpaste formulas; however, there is no evidence to determine its safety and effectiveness.[26]
Red colobus monkeys in Africa have been observed eating charcoal for self-medication. Because their leafy diets contain high levels ofcyanide, which may lead to indigestion, they learned to consume charcoal, which absorbs the cyanide and relieves discomfort. This knowledge is transmitted from mother to infant.[27]
Production and utilization of charcoal, like any use of woody biomass as fuel, typically results in emissions and can contribute to deforestation.
The use of charcoal as a smelting fuel has been experiencing a resurgence inSouth America resulting in severe environmental, social and medical problems.[28][29] Charcoal production at a sub-industrial level is one of the causes of deforestation. Charcoal production is now usually illegal and nearly always unregulated, as inBrazil, where charcoal production is a large illegal industry for makingpig iron.[30][31][32]
Massive forest destruction has been documented in areas such asVirunga National Park in theDemocratic Republic of Congo, where it is considered a primary threat to the survival of the mountain gorillas.[33] Similar threats are found inZambia.[34] InMalawi, illegal charcoal trade employs 92,800 workers and is the main source of heat and cooking fuel for 90 percent of the nation's population.[35] Some experts, such as Duncan MacQueen, Principal Researcher–Forest Team,International Institute for Environment and Development (IIED), argue that while illegal charcoal production causes deforestation, a regulated charcoal industry that required replanting and sustainable use of the forests "would give their people clean efficient energy – and their energy industries a strong competitive advantage".[35]
Recent assessments of charcoal imported to Europe have shown that many charcoal products are produced from tropical wood, often of undeclared origin. In an analysis of barbecue charcoal marketed in Germany, theWorld Wildlife Fund found that most products contain tropical wood. As a notable exception, reference is made to barbecue charcoal imports fromNamibia, where charcoal is typically produced from surplus biomass resulting fromwoody plant encroachment.[36][37][38]Charcoal trafficking in Somalia is an economic and environmental issue with significant regional-security implications.[39]
The last section of the filmLe Quattro Volte (2010) gives a good and long, if poetic, documentation of the traditional method of making charcoal.[40] TheArthur Ransome children's seriesSwallows and Amazons (particularly the second book,Swallowdale) features carefully drawn vignettes of the lives and the techniques of charcoal burners at the start of the 20th century, in theLake District of the UK.Antonín Dvořák's operaKing and Charcoal Burner is based on a Czech legend about a king who gets lost in a forest and is rescued by a charcoal burner.
^Updated April 26, 2018 By Gabriella Munoz (26 April 2018)."How Hot Is a Bonfire?". Sciencing. Retrieved13 November 2019.{{cite web}}: CS1 maint: numeric names: authors list (link)
^Damerow, Gail (2015).The Chicken Health Handbook, 2nd Edition: A Complete Guide to Maximizing Flock Health and Dealing with Disease. Storey. p. 391.ISBN978-1612120133.
^Am J Gastroenterology 2005 Feb 100(2)397–400 and 1999 Jan 94(1) 208–12
^Passali, Desiderio (1984). "Experiences in the determination of nasal mucociliary transport time".Acta Otolaryngol.97 (3–4):319–23.doi:10.3109/00016488409130995.PMID6539042.
^Brooks, John K.; Bashirelahi, Nasir; Reynolds, Mark A. (7 June 2017). "Charcoal and charcoal-based dentifrices: A literature review".Journal of the American Dental Association.148 (9):661–670.doi:10.1016/j.adaj.2017.05.001.ISSN1943-4723.PMID28599961.
^The documentary filmThe Charcoal People (2000)[1] shows in detail thedeforestation in Brazil, the poverty of the laborers and their families, and the method of constructing and using a clamp for burning the wood.
^Gridneff, Ilya (2018). "Burning Somalia's Future: The Illegal Charcoal Trade Between the Horn of Africa and the Gulf". In Verhoeven, Harry (ed.).Environmental Politics in the Middle East. Oxford: Oxford University Press. pp. 121–148.ISBN9780190916688.
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