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A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also be a plant where steel semi-finished casting products are made from molten pig iron or from scrap.
Since the invention of the Bessemer process, steel mills have replaced ironworks, based on puddling or fining methods. New ways to produce steel appeared later: from scrap melted in an electric arc furnace and, more recently, from direct reduced iron processes.
In the late 19th and early 20th centuries the world's largest steel mill was the Barrow Hematite Steel Company steelworks located in Barrow-in-Furness, United Kingdom. Today, the world's largest steel mill is in Gwangyang, South Korea. [1] [2]
An integrated steel mill has all the functions for primary steel production:
The principal raw materials for an integrated mill are iron ore, limestone, and coal (or coke). These materials are charged in batches into a blast furnace where the iron compounds in the ore give up excess oxygen and become liquid iron. At intervals of a few hours, the accumulated liquid iron is tapped from the blast furnace and either cast into pig iron or directed to other vessels for further steel making operations. Historically the Bessemer process was a major advancement in the production of economical steel, but it has now been entirely replaced by other processes such as the basic oxygen furnace.
Molten steel is cast into large blocks called blooms. During the casting process various methods are used, such as addition of aluminum, so that impurities in the steel float to the surface where they can be cut off the finished bloom.
Because of the energy cost and structural stress associated with heating and cooling a blast furnace, typically these primary steel making vessels will operate on a continuous production campaign of several years duration. Even during periods of low steel demand, it may not be feasible to let the blast furnace grow cold, though some adjustment of the production rate is possible.
Integrated mills are large facilities that are typically only economical to build in 2,000,000-ton per year annual capacity and up. Final products made by an integrated plant are usually large structural sections, heavy plate, strip, wire rod, railway rails, and occasionally long products such as bars and pipe.
A major environmental hazard associated with integrated steel mills is the pollution produced in the manufacture of coke, which is an essential intermediate product in the reduction of iron ore in a blast furnace.
Integrated mills may also adopt some of the processes used in mini-mills, such as arc furnaces and direct casting, to reduce production costs.
A minimill is traditionally a secondary steel producer; however, Nucor (one of the world's largest steel producers) and Commercial Metals Company (CMC) use minimills exclusively. Usually it obtains most of its iron from scrap steel, recycled from used automobiles and equipment or byproducts of manufacturing. Direct reduced iron (DRI) is sometimes used with scrap, to help maintain desired chemistry of the steel, though usually DRI is too expensive to use as the primary raw steelmaking material. A typical mini-mill will have an electric arc furnace for scrap melting, a ladle furnace or vacuum furnace for precision control of chemistry, a strip or billet continuous caster for converting molten steel to solid form, a reheat furnace and a rolling mill.
Originally the minimill was adapted to production of bar products only, such as concrete reinforcing bar, flats, angles, channels, pipe, and light rails. Since the late 1980s, successful introduction of the direct strip casting process has made minimill production of strip feasible. Often a minimill will be constructed in an area with no other steel production, to take advantage of local markets, resources, or lower-cost labour. Minimill plants may specialize, for example, in making coils of rod for wire-drawing use, or pipe, or in special sections for transportation and agriculture.
Capacities of minimills vary: some plants may make as much as 3,000,000 tons per year, a typical size is in the range 200,000 to 400,000 tons per year, and some old or specialty plants may make as little as 50,000 tons per year of finished product. Nucor Corporation, for example, annually produces around 9,100,000 tons of sheet steel from its four sheet mills, 6,700,000 tons of bar steel from its 10 bar mills and 2,100,000 tons of plate steel from its two plate mills.
Since the electric arc furnace can be easily started and stopped on a regular basis, minimills can follow the market demand for their products easily, operating on 24-hour schedules when demand is high and cutting back production when sales are lower.
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.
The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be classified as ferrous, ferroalloy or non-ferrous/base metals. Within these general categories, slags can be further categorized by their precursor and processing conditions. Slag generated from the EAF process can contain toxic metals, which can be hazardous to human and environmental health.
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.
Nucor Corporation is an American company based in Charlotte, North Carolina, that produces steel and related products. It is the largest steel producer in the United States and the largest recycler of scrap in North America. Nucor is the 16th-largest steel producer in the world. Along with Commercial Metals Company, it is one of two primary suppliers of rebar used to reinforce concrete in buildings, bridges, roads, and infrastructure in the U.S.
An open-hearth furnace or open hearth furnace is any of several kinds of industrial furnace in which excess carbon and other impurities are burnt out of pig iron to produce steel. Because steel is difficult to manufacture owing to its high melting point, normal fuels and furnaces were insufficient for mass production of steel, and the open-hearth type of furnace was one of several technologies developed in the nineteenth century to overcome this difficulty. Compared with the Bessemer process, which it displaced, its main advantages were that it did not expose the steel to excessive nitrogen, was easier to control, and permitted the melting and refining of large amounts of scrap iron and steel.
An electric arc furnace (EAF) is a furnace that heats material by means of an electric arc.
An ironworks or iron works is an industrial plant where iron is smelted and where heavy iron and steel products are made. The term is both singular and plural, i.e. the singular of ironworks is ironworks.
ArcelorMittal South Africa is part of the steel company Arcelor-Mittal. The company was originally Iscor Ltd., a South African parastatal steel company. It was founded in 1928 and was first listed on the JSE Securities Exchange in 1989.
Hyundai Steel Co., Ltd, or HSC is a steel making company headquartered in Incheon and Seoul, South Korea, and a member of the Hyundai Motor Group. It manufactures a wide variety of products ranging from H-beams, rail and reinforcing bars, to hot coil, cold-rolled steel, and stainless cold-rolled sheet.
FINEX is the name for an iron making technology developed by former Siemens VAI and POSCO. Molten iron is produced directly using iron ore fines and non-coking coal rather than traditional blast furnace methods through sintering and reduction with coke. Elimination of preliminary processing is claimed to make the plant for FINEX less expensive to build than a blast furnace facility of the same scale, additionally a 10-15% reduction in production costs is expected/claimed through cheaper raw materials, reduction of facility cost, pollutant exhaustion, maintenance staff and production time. The process is claimed to produce less pollutants such as SOx, NOx, and carbon dioxide than traditional methods.
Port Talbot Steelworks is a steel mill in Port Talbot, Wales. Over 4,000 people worked at the plant until the last blast furnace closed in October 2024. Around 2,000 employees remain after this time, processing imported steel slabs to produce rolled steel products. The mill is in the process of building a 320-ton capacity electric arc furnace which would be operational in late 2027.
The Park Gate Iron and Steel Company was a British company that smelted iron ore and turned it into rolled steel and semi-finished casting products. Its works was at Parkgate, South Yorkshire on a triangular site bounded on two sides by the main road between Rotherham and Barnsley (A633) and the North Midland Railway main line between Rotherham Masborough and Cudworth. It also operated ironstone quarries in Northamptonshire and Leicestershire.
The Ravenscraig steelworks, operated by Colvilles and from 1967 by British Steel Corporation, consisted of an integrated iron and steel works and a hot strip steel mill. They were located in Motherwell, North Lanarkshire, Scotland.
PT Krakatau Steel (Persero) Tbk is the largest steel maker in Indonesia, headquartered in Cilegon, Banten. The factory is set on a 280-hectare (700-acre) plot in the western end of Banten and adjacent to the Sunda Strait, and where the Krakatoa volcano and island from which the company takes its name are located.
Ebbw Vale Steelworks was an integrated steel mill located in Ebbw Vale, South Wales. Developed from 1790, by the late 1930s it had become the largest steel mill in Europe. It was nationalised after World War II. As the steel industry changed to bulk handling, iron and steel making was ceased in the 1970s, and the site was redeveloped as a specialised tinplate works. It was closed by Corus in 2002, but is being redeveloped in a joint partnership between Blaenau Gwent Council and the Welsh Government.
This steelmaking plant was originally part of the Ford Motor Company, which created an integrated manufacturing complex to produce all major vehicle components at one large facility called The Rouge. In 1989, Ford's steel mill assets were divested and became known as Rouge Industries with the steel operations trading as Rouge Steel Company in Dearborn, Michigan, outside of Detroit.
The Iron and Steel Industry in Scunthorpe was established in the mid 19th century, following the discovery and exploitation of middle Lias ironstone east of Scunthorpe, Lincolnshire, England.
In 2022, the United States was the world's third-largest producer of raw steel, and the sixth-largest producer of pig iron. The industry produced over 74 million net tons per year as of November 2024. Most iron and steel in the United States is now made from iron and steel scrap, rather than iron ore. The United States is also a major importer of iron and steel, as well as iron and steel products.
The US iron and steel industry has paralleled the industry in other countries in technological developments. In the 1800s, the US switched from charcoal to coal in ore smelting, adopted the Bessemer process, and saw the rise of very large integrated steel mills. In the 20th century, the US industry successively adopted the open hearth furnace, then the basic oxygen steelmaking process. Since the American industry peaked in the 1940s and 1950s, the US industry has shifted to small mini-mills and specialty mills, using iron and steel scrap as feedstock, rather than iron ore.
The Lithgow Blast Furnace is a heritage-listed former blast furnace and now park and visitor attraction at Inch Street, Lithgow, City of Lithgow, New South Wales, Australia. It was built from 1906 to 1907 by William Sandford Limited. It is also known as Eskbank Ironworks Blast Furnace site; Industrial Archaeological Site. The property is owned by Lithgow City Council. It was added to the New South Wales State Heritage Register on 2 April 1999.
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