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90-466: Bolckow, Vaughan & Co., Ltd was an English ironmaking and mining company founded in 1864, based on the partnership since 1840 of its two founders, Henry Bolckow and John Vaughan . The firm drove the dramatic growth of Middlesbrough and the production of coal and iron in the north-east of England in the 19th century. The two founding partners had an exceptionally close working relationship which lasted until Vaughan's death. By 1907 Bolckow, Vaughan

180-408: A ladle . In this step, the oxygen binds with the undesired carbon, carrying it away in the form of carbon dioxide gas, an additional source of emissions. After this step, the carbon content in the pig iron is lowered sufficiently and steel is obtained. Further carbon dioxide emissions result from the use of limestone , which is melted at high temperatures in a reaction called calcination , which has

270-410: A " carbon offset ", where emissions are "traded" against the sequestration of the source biomass, "ofsetting" emissions by 5% to 28% of current CO 2 values. Offsetting has a very low reputation globally, as cutting down the trees to create the pellets or charcoal does not sequester carbon, it interrupts the natural sequestration the tree was providing. Offsetting is not reduction. Overall, there are

360-418: A French mineralogist and geologist whom it is named after. He recognized and described the distinct characteristics of dolomite in the late 18th century, differentiating it from limestone. Most dolomite was formed as a magnesium replacement of limestone or of lime mud before lithification . The geological process of conversion of calcite to dolomite is known as dolomitization and any intermediate product

450-479: A batch ("heat") of iron is loaded into the furnace, sometimes with a "hot heel" (molten steel from a previous heat). Gas burners may be used to assist with the melt. As in basic oxygen steelmaking, fluxes are also added to protect the lining of the vessel and help improve the removal of impurities. Electric arc furnace steelmaking typically uses furnaces of capacity around 100 tonnes that produce steel every 40 to 50 minutes. This process allows larger alloy additions than

540-455: A depth of 1,300 feet (400 metres) below the surface, but it proved too costly to mine conventionally because of continual flooding, and mining was abandoned. However, in 1882 the technique of hydraulic extraction of salt was introduced. Salt was brought to the surface by pumping fresh water down a borehole, allowing the salt to dissolve, and pumping the brine back up. Production by Bolckow, Vaughan and other companies reached 300,000 tons per year in

630-434: A drop of dilute hydrochloric acid is dropped on it. This distinguishes dolomite from limestone, which is also soft but reacts vigorously with dilute hydrochloric acid. Dolomite usually weathers to a characteristic dull yellow-brown color due to the presence of ferrous iron. This is released and oxidized as the dolomite weathers. Dolomite is usually granular in appearance, with a texture resembling grains of sugar . Under

720-405: A high percentage of CaMg(CO 3 ) 2 in which natural caves or solution tubes have formed. Both calcium and magnesium go into solution when dolomite rock is dissolved. The speleothem precipitation sequence is: calcite , Mg-calcite, aragonite , huntite and hydromagnesite . Hence, the most common speleothem (secondary deposit) in caves within dolomite rock karst , is calcium carbonate in

810-544: A high-calcium limestone, such as manufacture of sodium carbonate . Dolomite is used for production of magnesium chemicals, such as Epsom salt , and is used as a magnesium supplement. It is also used in the manufacture of refractory materials . As with limestone caves , natural caves and solution tubes typically form in dolomite rock as a result of the dissolution by weak carbonic acid. Caves can also, less commonly, form through dissolution of rock by sulfuric acid . Calcium carbonate speleothems (secondary deposits) in

900-507: A number of innovative methods to reduce CO 2 emissions within the steelmaking industry. Some of these, such as top gas recovery and using hydrogen reduction in DRI/EAF are highly feasible with current infrastructure and technology levels. Others, such as hydrogen plasma and iron ore electrolysis are still in the research or semi-industrial stage. Dolomite (rock) Dolomite (also known as dolomite rock , dolostone or dolomitic rock )

990-567: A pair of sisters, which may explain their close friendship. In 1846, Bolckow and Vaughan built their first blast furnaces at Witton Park , founding the Witton Park Ironworks . The works used coal from Witton Park Colliery to make coke , and ironstone from Whitby on the coast. The pig iron produced at Witton was transported to Middlesbrough for further forging or casting. In 1850, Vaughan and his mining geologist John Marley discovered iron ore, conveniently situated near Eston in

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1080-652: A pilot plant in Woburn, Massachusetts , and building a production facility in Brazil, it was founded by MIT professors Donald Sadoway and Antoine Allanore. A research project which involved the steel company ArcelorMittal tested a different type of iron ore electrolysis process in a pilot project called Siderwin. It operates on relatively low temperatures (around 110 °C), while the Boston Metal process operates on high temperatures (~1.600 °C). As of March 2023 ArcelorMittal

1170-566: A result, attempts to precipitate dolomite from seawater precipitate high-magnesium calcite instead. This substance, which has an excess of calcium over magnesium and lacks calcium-magnesium ordering, is sometimes called protodolomite . Raising the temperature makes it easier for magnesium to shed its hydration shell, and dolomite can be precipitated from seawater at temperatures in excess of 60 °C (140 °F). Protodolomite also rapidly converts to dolomite at temperatures of 250 °C (482 °F) or higher. The high temperatures necessary for

1260-453: A very high ratio of calcium to magnesium. Dolomite is used for many of the same purposes as limestone, including as construction aggregate ; in agriculture to neutralize soil acidity and supply calcium and magnesium; as a source of carbon dioxide ; as dimension stone ; as a filler in fertilizers and other products; as a flux in metallurgy ; and in glass manufacturing . It cannot substitute for limestone in chemical processes that require

1350-461: Is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite , CaMg(CO 3 ) 2 . It occurs widely, often in association with limestone and evaporites , though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). One of the first geologists to distinguish dolomite from limestone was Déodat Gratet de Dolomieu;

1440-427: Is a method of primary steelmaking in which carbon-rich pig iron is melted and converted into steel. Blowing oxygen through molten pig iron converts some of the carbon in the iron into CO and CO 2 , turning it into steel. Refractories — calcium oxide and magnesium oxide —line the smelting vessel to withstand the high temperature and corrosive nature of the molten metal and slag . The chemistry of

1530-451: Is also rich in the reducing agents of H 2 and CO. The top gas can be captured, the CO 2 removed, and the reducing agents reinjected into the blast furnace. A 2012 study suggested that this process can reduce BF CO 2 emissions by 75%, while a 2017 study showed that emissions are reduced by 56.5% with carbon capture and storage, and reduced by 26.2% if only the recycling of the reducing agents

1620-451: Is and ongoing project by SuSteel to develop a hydrogen plasma technology that reduces the oxides with hydrogen, as opposed to with CO or carbon, and melts the iron at high operating temperatures. In steelmaking, coal and coke are used for fuel and iron reduction. Biomass such as charcoal or wood pellets are a potential alternative fuel, but this does not actually reduce emissions, as the burning biomass still emits carbon, it merely provides

1710-467: Is characterized by its nearly ideal 1:1 stoichiometric ratio of magnesium to calcium. It is distinct from high-magnesium limestone in that the magnesium and calcium form ordered layers within the individual dolomite mineral grains, rather than being arranged at random, as they are in high-magnesium calcite grains. In natural dolomite, magnesium is typically between 44 and 50 percent of total magnesium plus calcium, indicating some substitution of calcium into

1800-401: Is infused with carbon (from coal) in an electric arc furnace . Hydrogen produced by electrolysis requires approximately 2600 kWh per ton of steel. Costs are estimated to be 20–30% higher than conventional methods. However, the cost of CO 2 -emissions add to the price of basic oxygen production, and a 2018 study of Science magazine estimates that the prices will break even when that price

1890-472: Is investigating whether the company wants scale up the technology and build a larger plant, and expects an investment decision by 2025. Scrap in steelmaking refers to steel that has either reached its end-of-life use, or was generated during the manufacture of steel components. Steel is easy to separate and recycle due to its inherent magnetism and using scrap avoids the emissions of 1.5 tons of CO 2 for every ton of scrap used. As of 2023 , steel has one of

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1980-446: Is iron ore electrolysis, where the reducing agent is simply electrons as opposed to H 2 , CO, or carbon. One method for this is molten oxide electrolysis. Here, the cell consists of an inert anode, a liquid oxide electrolyte (CaO, MgO, etc.), and the molten steel. When heated, the iron ore is reduced to iron and oxygen. Boston Metal is at the semi-industrial stage for this process, with plans to reach commercialization by 2026. Expanding

2070-413: Is known as dolomitic limestone . The "dolomite problem" refers to the vast worldwide depositions of dolomite in the past geologic record in contrast to the limited amounts of dolomite formed in modern times. Recent research has revealed sulfate-reducing bacteria living in anoxic conditions precipitate dolomite which indicates that some past dolomite deposits may be due to microbial activity. Dolomite

2160-626: Is no consistent trend in its abundance with age, but most dolomite appears to have formed at high stands of sea level. Little dolomite is found in Cenozoic beds (beds less than 65 million years old), which has been a time of generally low sea levels. Times of high sea level also tend to be times of a greenhouse Earth , and it is possible that greenhouse conditions are the trigger for dolomite formation. Many dolomites show clear textural indications that they are secondary dolomites, formed by replacement of limestone. However, although much research has gone into understanding this process of dolomitization ,

2250-423: Is not seen to precipitate in the oceans. Likewise, geologists have not been successful at precipitating dolomite from seawater at normal temperatures and pressures in laboratory experiments. This is likely due to a very high activation energy for nucleating crystals of dolomite. The magnesium ion is a relatively small ion, and it acquires a tightly bound hydration shell when dissolved in water. In other words,

2340-440: Is not very strong, but a low concentration of carbon – less than 1 percent, depending on the kind of steel – gives the steel its important properties. The carbon in steel is obtained from coal and the iron from iron ore. However, iron ore is a mixture of iron and oxygen, and other trace elements. To make steel, the iron needs to be separated from the oxygen and a tiny amount of carbon needs to be added. Both are accomplished by melting

2430-419: Is resistant to erosion and can either contain bedded layers or be unbedded. It is less soluble than limestone in weakly acidic groundwater , but it can still develop solution features ( karst ) over time. Dolomite rock can act as an oil and natural gas reservoir. Dolomite takes its name from the 18th-century French mineralogist Déodat Gratet de Dolomieu (1750–1801), who was one of the first to describe

2520-416: Is secondary, formed by replacement of calcium by magnesium in limestone. The preservation of the original limestone texture can range from almost perfectly preserved to completely destroyed. Under a microscope, dolomite rhombs are sometimes seen to replace oolites or skeletal particles of the original limestone. There is sometimes selective replacement of fossils, with the fossil remaining mostly calcite and

2610-538: Is stained by Alizarin Red S while dolomite grains are not. Dolomite rock consisting of well-formed grains with planar surfaces is described as planar or idiotopic dolomite, while dolomite consisting of poorly-formed grains with irregular surfaces is described as nonplanar or xenotopic dolomite. The latter likely forms by recrystallization of existing dolomite at elevated temperature (over 50 to 100 °C (122 to 212 °F)). The texture of dolomite often shows that it

2700-543: Is subject to high rates of evaporation. This results in precipitation of gypsum and aragonite , raising the magnesium to calcium ratio of the remaining brine. The brine is also dense, so it sinks into the pore space of any underlying limestone ( seepage refluxion ), flushing out the existing pore fluid and causing dolomitization. The Permian Basin of North America has been put forward as an example of an environment in which this process took place. A variant of this model has been proposed for sabkha environments in which brine

2790-630: Is sucked up into the dolomitizing limestone by evaporation of capillary fluids, a process called evaporative pumping . Another model is the mixing-zone or Dorag model, in which meteoric water mixes with seawater already present in the pore space, increasing the chemical activity of magnesium relative to calcium and causing dolomitization. The formation of Pleistocene dolomite reefs in Jamaica has been attributed to this process. However, this model has been heavily criticized, with one 2004 review paper describing it bluntly as "a myth". A 2021 paper argued that

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2880-573: Is the most prominent among green steel technologies. This differs from conventional steel making processes, in which carbon in coke is used as the reductant (to strip oxygen from iron ore), which creates iron and carbon dioxide. Where hydrogen is generated from a renewable energy source as both the alternative reductant and the fuel, the greatest gain in CO 2 emissions is achieved. As of 2021, only ArcelorMittal in France, Voestalpine in Austria, and TATA in

2970-476: Is thermodynamically favorable, with a Gibbs free energy of about -2.2 kcal/mol. In theory, ordinary seawater contains sufficient dissolved magnesium to cause dolomitization. However, because of the very slow rate of diffusion of ions in solid mineral grains at ordinary temperatures, the process can occur only by simultaneous dissolution of calcite and crystallization of dolomite. This in turn requires that large volumes of magnesium-bearing fluids are flushed through

3060-413: Is used. To keep the carbon captured from entering the atmosphere, a method of storing it or using it would have to be found. Another way to use the top gas would be in a top recovery turbine which then generates electricity, which could be used to reduce the energy intensity of the process, if electric arc smelting is used. Carbon could also be captured from gases in the coke oven. As of 2022 , separating

3150-451: Is €68 per tonne CO 2 , which is expected to be reached in the 2030s. Secondary steelmaking is most commonly performed in ladles . Some of the operations performed in ladles include de-oxidation (or "killing"), vacuum degassing, alloy addition, inclusion removal, inclusion chemistry modification, de-sulphurisation, and homogenisation. It is now common to perform ladle metallurgical operations in gas-stirred ladles with electric arc heating in

3240-607: The Cleveland Hills of Yorkshire . Unknown to anyone at the time, this vein was part of the Cleveland Ironstone Formation , which was already being mined in Grosmont by Losh, Wilson and Bell . To make use of the ore being mined at Eston, Bolckow and Vaughan built a blast furnace in 1851 at nearby South Bank, Middlesbrough , enabling the entire process from rock to finished products to be carried out in one place. It

3330-567: The New Sculpture movement. Bulmer's Gazetteer of 1890 records that in 1888 Bolckow, Vaughan owned 6 of the 36 ironstone mines in Cleveland and Whitby; the ironstone in their mine at Eston contained 33.62% Iron. By 1887 the company owned 4 of the 21 ironworks in Cleveland, with 21 of the 91 blast furnaces. In the 1900s, Bolckow, Vaughan was certainly the largest steel producer in Britain, and possibly

3420-447: The industrial process in which coal is used as the source of carbon that removes oxygen from iron ore in the following chemical reaction, which occurs in a blast furnace : Fe 2 O 3 (s) + 3 CO(g) → 2 Fe(s) + 3 CO 2 (g) Additional carbon dioxide emissions result from mining, refining and shipping the ore used, basic oxygen steelmaking , calcination , and the hot blast . Proposed techniques to reduce carbon dioxide emissions in

3510-489: The 1890s. On 2 June 1884, Sir Joseph Pease unveiled a monument to John Vaughan in Exchange Square, Middlesbrough, which still stands. He gave a speech to the crowd of 15,000 people, in which he described the town as "the greatest iron-producing district in the world", and compared Bolckow and Vaughan to the mythical founding fathers of Rome, Romulus and Remus . The bronze statue was sculpted by George Anderson Lawson of

3600-505: The British government during the war, leading to reliance on costly bank loans in 1918, rather than issuing share capital as the firm later did in 1919 and 1923; failure to diversify into profitable steel products such as pipes, sheet steel and shipbuilding plates; and failure to invest in its own coal mines to provide enough for steel production, and for cash. There were thus both long-term and short-term failures of strategy. No company history

3690-555: The CO2 from other gases and components in the system, and the high cost of the equipment and infrastructure changes needed, have kept this strategy minimal, but the potential for emission reduction has been estimated to be up to 65% to 80%. Alternatively, hydrogen can be used in a shaft furnace to reduce the iron oxides. Only water is produced as the by-product of the reaction between iron oxide and hydrogen, and results in emission-free iron-making. Known as hydrogen direct reduction (HDR), this

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3780-517: The Eston Ironworks acquired a rolling mill engine from the Vulcan Iron Works of Thwaites and Carbutt , Bradford. It had a 36-inch (910 mm) bore, and a 54-inch (1,400 mm) stroke. A profitable sideline to the production of iron was salt. In 1863, John Marley discovered a deposit of rock salt at Middlesbrough while drilling for water. The salt bed was 100 feet (30 metres) thick at

3870-559: The HIsarna process is more energy-efficient and has a lower carbon footprint than traditional steelmaking processes. Steel can be produced from direct-reduced iron, which in turn can be produced from iron ore as it undergoes chemical reduction with hydrogen. Renewable hydrogen allows steelmaking without the use of fossil fuels . In 2021, a pilot plant in Sweden tested this process. Direct reduction occurs at 1,500 °F (820 °C). The iron

3960-586: The Netherlands were committed to using green hydrogen to make steel from scratch. HDR is employed in the HYBRIT project in Sweden. However, this approach requires a substantial amount of renewables to produce the needed renewable hydrogen. For the European Union, it is estimated that the hydrogen demand for hydrogen-based steelmaking would require 180 GW of renewable capacity. Another developing possible technology

4050-526: The River Tees Dockyard is still marked by boundary stones on Smiths Dock Road, Middlesbrough. The graves of the founding fathers of the company and of Middlesbrough, Henry Bolckow and John Vaughan, in St Cuthbert's Churchyard, Marton , fell into disrepair. They were refurbished in 2009. Steelmaking Steelmaking has existed for millennia, but it was not commercialized on a massive scale until

4140-407: The air in the hot blast is heated by burning fossil fuels, which often is the case, this is an additional source of carbon dioxide emissions. The steel industry produces 7-8% of CO 2 emissions created by humans (almost two tonnes for every tonne of steel produced), and it is one of the most energy-consuming industries on earth. There are several carbon abatement and decarbonization strategies in

4230-504: The banks of the River Tees . In 1868, Vaughan died. The Institution of Civil Engineers , in their obituary, commented on the relationship between Vaughan and Bolckow: " There was indeed something remarkable in the thorough division of labour in the management of the affairs of the firm. While possessing the most unbounded confidence in each other, the two partners never interfered in the slightest degree with each other's work. Mr. Bolckow had

4320-407: The basic oxygen method. In HIsarna ironmaking process, iron ore is processed almost directly into liquid iron or hot metal . The process is based around a type of blast furnace called a cyclone converter furnace , which makes it possible to skip the process of manufacturing pig iron pellets that is necessary for the basic oxygen steelmaking process. Without the necessity of this preparatory step,

4410-463: The blast furnace where the iron ore is reduced to pig iron, helping to achieve the high activation energy. The hot blast temperature can be from 900 to 1,300 °C (1,650 to 2,370 °F) depending on the stove design and condition. Oil, tar , natural gas, powdered coal and oxygen can also be injected into the furnace to combine with the coke to release additional energy and increase the percentage of reducing gases present, increasing productivity. If

4500-401: The calcium oxide can react to remove silicon oxide impurities: SiO 2 + CaO → CaSiO 3 This use of limestone to provide a flux occurs both in the blast furnace (to obtain pig iron) and in the basic oxygen steel making (to obtain steel). Further carbon dioxide emissions result from the hot blast , which is used to increase the heat of the blast furnace. The hot blast pumps hot air into

4590-599: The classical era in Ancient China , India , and Rome . Cast iron is a hard, brittle material that is difficult to work, whereas steel is malleable, relatively easily formed and a versatile material. For much of human history, steel has only been made in small quantities. Since the invention of the Bessemer process in 19th century Britain and subsequent technological developments in injection technology and process control , mass production of steel has become an integral part of

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4680-555: The entire management of the financial department, while Mr. Vaughan as worthily controlled the practical work of the establishment. " In 1871, Edward Johnson-Ferguson (1849–1929) became a director of Bolckow & Vaughan; he became chairman and managing director (and was knighted) in 1906, remaining so until his death. In 1875, Edward Windsor Richards became the General Manager of the Middlesbrough Ironworks. Richards

4770-418: The following chemical reaction: CaCO 3 (s) → CaO(s) + CO 2 (g) Carbon dioxide is an additional source of emissions in this reaction. Modern industry has introduced calcium oxide (CaO, quicklime ) as a replacement. It acts as a chemical flux , removing impurities (such as Sulfur or Phosphorus (e.g. apatite or fluorapatite ) ) in the form of slag and keeps emissions of CO 2 low. For example,

4860-531: The formation of dolomite helps explain the rarity of Cenozoic dolomites, since Cenozoic seawater temperatures seldom exceeded 40 °C. It is possible that microorganisms are capable of precipitating primary dolomite. This was first demonstrated in samples collected at Lagoa Vermelha , Brazil in association with sulfate-reducing bacteria ( Desulfovibrio ), leading to the hypothesis that sulfate ion inhibits dolomite nucleation. Later laboratory experiments suggest bacteria can precipitate dolomite independently of

4950-479: The forms of stalactites , stalagmites , flowstone etc., can also form in caves within dolomite rock. “Dolomite is a common rock type, but a relatively uncommon mineral in speleothems”. Both the 'Union Internationale de Spéléologie' (UIS) and the American 'National Speleological Society' (NSS), extensively use in their publications, the terms "dolomite" or "dolomite rock" when referring to the natural bedrock containing

5040-467: The global economy and a key indicator of modern technological development. The earliest means of producing steel was in a bloomery . Early modern methods of producing steel were often labor-intensive and highly skilled arts. See: An important aspect of the Industrial Revolution was the development of large-scale methods of producing forgeable metal ( bar iron or steel). The puddling furnace

5130-404: The greater temperatures characterizing deeper burial, if a mechanism exists to flush magnesium-bearing fluids through the beds. Mineral dolomite has a 12% to 13% smaller volume than calcite per alkali cation. Thus dolomitization likely increases porosity and contributes to the sugary texture of dolomite. Dolomite is supersaturated in normal seawater by a factor of greater than ten, but dolomite

5220-456: The high temperatures are needed to achieve the activation energy for this reaction. A small amount of carbon bonds with the iron, forming pig iron , which is an intermediary before steel, as it has carbon content that is too high – around 4%. To reduce the carbon content in pig iron and obtain the desired carbon content of steel, the pig iron is re-melted and oxygen is blown through in a process called basic oxygen steelmaking , which occurs in

5310-417: The highest recycling rates of any material, with around 30% of the world's steel being made from recycled components. However, steel cannot be recycled forever, and the recycling processes, using arc furnaces, use electricity. In the blast furnace, the iron oxides are reduced by a combination of CO, H 2 , and carbon. Only around 10% of the iron oxides are reduced by H 2 . With H 2 enrichment processing,

5400-448: The industry decreased by a factor of 1000, to just 0.003-man-hours per tonne. In 2013, 70% of global steel output was produced using the basic oxygen furnace. Furnaces can convert up to 350 tons of iron into steel in less than 40 minutes compared to 10–12 hours in an open hearth furnace . Electric arc furnace steelmaking is the manufacture of steel from scrap or direct reduced iron melted by electric arcs . In an electric arc furnace,

5490-473: The iron ore at a very high temperature (1,700 degrees Celsius or over 3,000 degrees Fahrenheit) in the presence of oxygen (from the air) and a type of coal called coke . At those temperatures, the iron ore releases its oxygen, which is carried away by the carbon from the coke in the form of carbon dioxide. Fe 2 O 3 (s) + 3 CO(g) → 2 Fe(s) + 3 CO 2 (g) The reaction occurs due to the lower (favorable) energy state of carbon dioxide compared to iron oxide, and

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5580-557: The largest in the world. In 1905, the firm produced 820,000 tons of pig iron , which was 8.5% of Great Britain's output, and twice as much as the next largest producer. In 1907 it was one of the largest firms in Britain, with 20,000 employees. In 1918, the firm even had its own women's football team . Bolckow, Vaughan's women workers were runners-up in a replayed final tie for the Tyne Wear & Tees Alfred Wood Munition Girls Cup . They were defeated 5–0 by Blyth Spartans . Fresh management

5670-448: The lid of the furnace. Tight control of ladle metallurgy is associated with producing high grades of steel in which the tolerances in chemistry and consistency are narrow. As of 2021 , steelmaking is estimated to be responsible for around 11% of the global emissions of carbon dioxide and around 7% of the global greenhouse gas emissions. Making 1 ton of steel emits about 1.8 tons of carbon dioxide. The bulk of these emissions results from

5760-437: The magnesium ion is surrounded by a clump of water molecules that are strongly attracted to its positive charge. Calcium is a larger ion and this reduces the strength of binding of its hydration shell, so it is much easier for a calcium ion than a magnesium ion to shed its hydration shell and bind to a growing crystal. It is also more difficult to nucleate a seed crystal of ordered dolomite than disordered high-magnesium calcite. As

5850-461: The magnesium layers. A small amount of ferrous iron typically substitutes for magnesium, particularly in more ancient dolomites. Carbonate rock tends to be either almost all calcite or almost all dolomite, with intermediate compositions being quite uncommon. Dolomite outcrops are recognized in the field by their softness (mineral dolomite has a Mohs hardness of 4 or less, well below common silicate minerals) and because dolomite bubbles feebly when

5940-445: The main feed materials. Oxygen steelmaking is fueled predominantly by the exothermic nature of the reactions inside the vessel; in contrast, in EAF steelmaking, electrical energy is used to melt the solid scrap and/or DRI materials. In recent times, EAF steelmaking technology has evolved closer to oxygen steelmaking as more chemical energy is introduced into the process. Steelmaking is one of

6030-451: The mechanism of dolomitization, the tendency of carbonate rock to be either almost all calcite or almost all dolomite suggests that, once the process is started, it completes rapidly. The process likely occurs at shallow depths of burial, under 100 meters (330 ft), where there is an inexhaustible supply of magnesium-rich seawater and the original limestone is more likely to be porous. On the other hand, dolomitization can proceed rapidly at

6120-571: The microscope, thin sections of dolomite usually show individual grains that are well-shaped rhombs , with considerable pore space. As a result, subsurface dolomite is generally more porous than subsurface limestone and makes up 80% of carbonate rock petroleum reservoirs . This texture contrasts with limestone, which is usually a mixture of grains, micrite (very fine-grained carbonate mud) and sparry cement. The optical properties of calcite and mineral dolomite are difficult to distinguish, but calcite almost never crystallizes as regular rhombs, and calcite

6210-561: The mid-19th century. An ancient process of steelmaking was the crucible process . In the 1850s and 1860s, the Bessemer process and the Siemens-Martin process turned steelmaking into a heavy industry . Today there are two major commercial processes for making steel, namely basic oxygen steelmaking , which has liquid pig-iron from the blast furnace and scrap steel as the main feed materials, and electric arc furnace (EAF) steelmaking, which uses scrap steel or direct reduced iron (DRI) as

6300-427: The mineral. The term dolomite refers to both the calcium-magnesium carbonate mineral and to sedimentary rock formed predominantly of this mineral. The term dolostone was introduced in 1948 to avoid confusion between the two. However, the usage of the term dolostone is controversial, because the name dolomite was first applied to the rock during the late 18th century and thus has technical precedence. The use of

6390-492: The mixing zone serves as domain of intense microbial activity which promotes dolomitization. A third model postulates that normal seawater is the dolomitizing fluid, and the necessary large volumes are flushed through the dolomitizing limestone through tidal pumping. Dolomite formation at Sugarloaf Key , Florida, may be an example of this process. A similar process might occur during rises in sea level, as large volumes of water move through limestone platform rock. Regardless of

6480-412: The most carbon emission intensive industries in the world. As of 2020 , steelmaking is responsible for about 10% of greenhouse gas emissions . To mitigate global warming , the industry will need to find significant reductions in emissions. Steelmaking has played a crucial role in the development of ancient, medieval, and modern technological societies. Early processes of steel making were made during

6570-427: The pore space in the dolomitizing limestone. Several processes have been proposed for dolomitization. The hypersaline model (also known as the evaporative reflux model ) is based on the observation that dolomite is very commonly found in association with limestone and evaporites , with the limestone often interbedded with the dolomite. According to this model, dolomitization takes place in a closed basin where seawater

6660-406: The process is controlled to ensure that impurities such as silicon and phosphorus are removed from the metal. The modern process was developed in 1948 by Robert Durrer , as a refinement of the Bessemer converter that replaced air with more efficient oxygen . It reduced the capital cost of the plants and smelting time, and increased labor productivity. Between 1920 and 2000, labour requirements in

6750-401: The process remains poorly understood. There are also fine-grained dolomites showing no textural indications that they formed by replacement, and it is uncertain whether they formed by replacement of limestone that left no textural traces or are true primary dolomites. This dolomite problem was first recognized over two centuries ago but is still not fully resolved. The dolomitization reaction

6840-415: The process, either in electric arc furnaces or to create hydrogen as a fuel, emissions can be reduced dramatically. European projects from HYBRIT, LKAB , Voestalpine , and ThyssenKrupp are pursuing strategies to reduce emissions. HYBRIT claims to produce true "green steel". Top gas from the blast furnace is the gas that is normally exhausted into the air during steelmaking. This gas contains CO 2 and

6930-428: The proportion of iron oxides reduced by H 2 is increased, so that less carbon is consumed and less CO 2 is emitted. This process can reduce emissions by an estimated 20%. The HIsarna ironmaking process was described above as a way of producing iron in a "cyclone converter furnace" without the pre-processing steps of choking/agglomeration, which reduces the CO 2 emissions by around 20%. One speculative idea

7020-456: The question of whether this can lead to precipitation of dolomite. Dolomitization can sometimes be reversed, and a dolomite bed converted back to limestone. This is indicated by a texture of pseudomorphs of mineral dolomite that have been replaced with calcite. Dedolomitized limestone is typically associated with gypsum or oxidized pyrite , and dedolomitization is thought to occur at very shallow depths through infiltration of surface water with

7110-505: The steel industry include reduction of iron ore using green hydrogen rather than carbon, and deployment of carbon capture and storage technology. See below for further decarbonization strategies. Coal and iron ore mining are very energy intensive, and result in numerous environmental damages , from pollution, to biodiversity loss, deforestation, and greenhouse gas emissions. Iron ore is shipped great distances to steel mills. To make pure steel, iron and carbon are needed. On its own, iron

7200-584: The steelmaking industry, which on the basic manufacturing process used. Options fall into three general categories: switching the energy source from fossil fuels to wind and solar ; increasing the efficiency of processing; and innovative new technological processes. All three may be used in combination. "Green steel" is the term used for manufacturing steel without the use of fossil fuels , that is, zero-emission products. However, not all companies claiming to produce green steel meet this criterion. Some merely reduce emissions. Australia produces nearly 40% of

7290-400: The sulfate concentration. With time other pathways of interaction between microbial activity and dolomite formation have been added to the discord regarding their role in modulation and generation of polysaccharides , manganese and zinc within the porewater. Meanwhile, a contrary view held by other researchers is that microorganisms precipitate only high-magnesium calcite but leave open

7380-422: The surrounding matrix composed of dolomite grains. Sometimes dolomite rhombs are seen cut across the fossil outline. However, some dolomite shows no textural indications that it was formed by replacement of limestone. Dolomite is widespread in its occurrences, though not as common as limestone. It is typically found in association with limestone or evaporite beds and is often interbedded with limestone. There

7470-526: The term dolostone was not recommended by the Glossary of Geology published by the American Geological Institute . In old USGS publications, dolomite was referred to as magnesian limestone , a term now reserved for magnesium -deficient dolomites or magnesium-rich limestones. Dolomite rock is defined as sedimentary carbonate rock composed of more than 50% mineral dolomite . Dolomite

7560-518: The world's iron ore, and the government, via the Australian Renewable Energy Agency (ARENA), is helping to fund many research projects involving direct reduced ironmaking (DRI) to increase green steel and iron production. Large companies such as Rio Tinto , BHP , and BlueScope are developing green steel projects. CO 2 emissions vary according to energy sources. When sustainable energy such as wind or solar are used to power

7650-484: Was brought into Bolckow Vaughan in the later 1920s, Holberry Mensforth as managing director working with Henry Duncan McLaren . The works were reorganised, and consultation with the workforce introduced. Financial pressures saw it undergo a merger with Dorman Long , in 1931. The causes of failure included: poor decision-making in the period from 1900 to 1910 which delayed the introduction of improved steelmaking technology; optimistic belief in promises of funding made by

7740-619: Was in charge of the design and construction of the new plant at Eston , the Cleveland Steel Works. It had three coke fired haematite blast furnaces. Richards' work helped to improve the Bessemer process for making steel, in the case when the ore is rich in phosphorus , and an alkaline rock ( dolomite , limestone or magnesite ) is used. This variant is called the Gilchrist-Thomas process, after its inventor Sidney Gilchrist Thomas who persuaded Richards to adopt it. In 1877,

7830-720: Was initially a means of producing wrought iron but was later applied to steel production. The real revolution in modern steelmaking only began at the end of the 1850s when the Bessemer process became the first successful method of steelmaking in high quantity followed by the open-hearth furnace . Modern steelmaking processes can be divided into three steps: primary, secondary and tertiary. Primary steelmaking involves smelting iron into steel. Secondary steelmaking involves adding or removing other elements such as alloying agents and dissolved gases. Tertiary steelmaking involves casting into sheets, rolls or other forms. Multiple techniques are available for each step. Basic oxygen steelmaking

7920-557: Was possibly the largest producer of pig iron in the world. The firm failed to modernise at the start of the 20th century, and was closed in 1929. In 1840, Henry Bolckow (1806–1878) and John Vaughan (1799–1868) set up in business in Middlesbrough to make iron. They lived side by side in two town houses, the Cleveland Buildings, about 400 yards (370 m) away from their ironworks which were on Vulcan Street, and they married

8010-697: Was the first to be built on Teesside , on what was later nicknamed "the Steel River". Middlesbrough grew from 40 inhabitants in 1829 to 7600 in 1851, 19,000 in 1861 and 40,000 in 1871, fuelled by the iron industry. In 1864, Bolckow, Vaughan and Company Ltd was registered with capital of £2,500,000, making it the largest company ever formed up to that time. By that time, the company's assets included iron mines , collieries , and limestone quarries in Cleveland , County Durham and Weardale respectively, and had iron and steel works extending over 700 acres (280 ha) along

8100-509: Was written. The rise and fall of the company can be seen in the numbers of mines and collieries that it owned: The production of pig-iron, which was once profitable, but later became a weakness when rivals were producing steel, shows growth and slow decline: Few visible signs of the company remain. The former extent of the Bolckow, Vaughan property at the Eston Sheet and Galvanizing Works beside

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