Coal miningCoal mining is the process of extracting coal from the ground or from a mine. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United Kingdom and South Africa, a coal mine and its structures are a colliery, a coal mine is called a 'pit', and the above-ground structures are a 'pit head'. In Australia, "colliery" generally refers to an underground coal mine.
Bituminous coalBituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. It is typically hard but friable. Its quality is ranked higher than lignite and sub-bituminous coal, but lesser than anthracite. It is the most abundant rank of coal, with deposits found around the world, often in rocks of Carboniferous age.
CharcoalCharcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern "charcoal" briquettes used for outdoor cooking may contain many other additives, e.
MethaneMethane (USˈmɛθeɪn , UKˈmiːθeɪn ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes.
CoalCoal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is a type of fossil fuel, formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands called coal forests that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.
Coke (fuel)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. The unqualified term "coke" usually refers to the product derived from low-ash and low-sulphur bituminous coal by a process called coking.
AnthraciteAnthracite, 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. Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 86% and 97%. The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition.
LigniteLignite (derived from Latin lignum meaning 'wood') often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat content. When removed from the ground, it contains a very high amount of moisture which partially explains its low carbon content. Lignite is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation.
Greenhouse gas emissionsGreenhouse gas emissions (abbreviated as GHG emissions) from human activities strengthen the greenhouse effect, contributing to climate change. Carbon dioxide (), from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the US, although the United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies.
Coal analysisCoal 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. Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal, anthracite and graphite. Each type of coal has a certain set of physical parameters which are mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons) and carbon content.
Coal in ChinaChina is the largest producer and consumer of coal and the largest user of coal-generated electricity in the world. The share of coal in the Chinese energy mix declined to 55% in 2021 according to the US Energy Information Agency. The Chinese central government has clamped down on the pace of new construction of coal plants and shifted to renewable, nuclear and natural gas sources. At the same time, coal consumption reached new heights in China with carbon dioxide emissions from coal-fired electricity production estimated to top 4.
CokingCoking is the heating of coal in the absence of oxygen to a temperature above 600 °C to drive off the volatile components of the raw coal, leaving a hard, strong, porous material of high carbon content called coke. Coke consists almost entirely of hydrocarbons. The porosity gives it a high surface area, which makes it burn faster (as does a sheet of paper versus a wooden log). When a kilogram of coke is burned it releases more heat than a kilogram of the original coal. Coke is used as fuel in a blast furnace.
Coal dustCoal dust is a fine-powdered form of coal which is created by the crushing, grinding, or pulverization of coal rock. Because of the brittle nature of coal, coal dust can be created by mining, transporting, or mechanically handling it. Grinding or pulverizing coal to a dust form before combusting it improves the speed and efficiency of burning, which makes the coal easier to handle. However, coal dust is hazardous to workers if it is suspended in air outside the controlled environment of grinding and combustion equipment.
Mond processThe Mond process, sometimes known as the carbonyl process, is a technique created by Ludwig Mond in 1890, to extract and purify nickel. The process was used commercially before the end of the 19th century, and particularly by the International Nickel Company in the Sudbury Basin. This process converts nickel oxides into nickel metal with very high purity being attainable in just a single step. This process involves the fact that carbon monoxide combines with nickel readily and reversibly to give nickel carbonyl.
Carbon monoxideCarbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest carbon oxide. In coordination complexes, the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds.
Metallurgical coalMetallurgical coal or coking coal 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. 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. Metallurgical coal comes mainly from Canada, the United States, and Australia, with Australia exporting 58% of seaborne trade, mostly going to China.
Health and environmental impact of the coal industryThe health and environmental impact of the coal industry includes issues such as land use, waste management, water and air pollution, caused by the coal mining, processing and the use of its products. In addition to atmospheric pollution, coal burning produces hundreds of millions of tons of solid waste products annually, including fly ash, bottom ash, and flue-gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals.
Coal-fired power stationA coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide there are over 2,400 coal-fired power stations, totaling over 2,000 gigawatts capacity. They generate about a third of the world's electricity, but cause many illnesses and the most early deaths, mainly from air pollution. A coal-fired power station is a type of fossil fuel power station. The coal is usually pulverized and then burned in a pulverized coal-fired boiler.
Heat of combustionThe heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it. The calorific value is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard conditions. The chemical reaction is typically a hydrocarbon or other organic molecule reacting with oxygen to form carbon dioxide and water and release heat.
Sub-bituminous coalSub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal. Sub-bituminous coal is primarily used as a fuel for steam-electric power generation. Sub-bituminous coals may be dull, dark brown to black, soft and crumbly at the lower end of the range, to bright jet-black, hard, and relatively strong at the upper end.
