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 .
61-533: Ironworks succeeded bloomeries when blast furnaces replaced former methods. An integrated ironworks in the 19th century usually included one or more blast furnaces and a number of puddling furnaces or a foundry with or without other kinds of ironworks. After the invention of the Bessemer process , converters became widespread, and the appellation steelworks replaced ironworks. The processes carried at ironworks are usually described as ferrous metallurgy, but
122-766: 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 (co-products of processing iron and steel), ferroalloy (a by-product of ferroalloy production) or non-ferrous / base metals (by-products of recovering non-ferrous materials like copper , nickel , zinc and phosphorus ). Within these general categories, slags can be further categorized by their precursor and processing conditions (e.g., blast furnace slags, air-cooled blast furnace slag, granulated blast furnace slag, basic oxygen furnace slag, and electric arc furnace slag). Slag generated from
183-453: A bloomery is iron that is easily forgeable , it requires a low carbon content. The temperature and ratio of charcoal to iron ore must be carefully controlled to keep the iron from absorbing too much carbon and thus becoming unforgeable. Cast iron occurs when the iron absorbs 2% to 4% carbon. Because the bloomery is self- fluxing , the addition of limestone is not required to form a slag. The small particles of iron produced in this way fall to
244-399: A bloomery's size is increased, the iron ore is exposed to burning charcoal for a longer time. When combined with the strong air blast required to penetrate the large ore and charcoal stack, this may cause part of the iron to melt and become saturated with carbon in the process, producing unforgeable pig iron, which requires oxidation to be reduced into cast iron, steel, and iron. This pig iron
305-432: A high iron content, it can also be broken up and may be recycled into the bloomery with the new ore. In operation, after the bloomery is heated typically with a wood fire, shifting to burning sized charcoal, iron ore and additional charcoal are introduced through the top. Again, traditional methods vary, but normally smaller charges of ore are added at the start of the main smelting sequence, increasing to larger amounts as
366-466: A higher carbon content) by manipulating the charge of and air flow to the bloomery is also possible. As the era of modern commercial steelmaking began, the word "bloom" was extended to another sense referring to an intermediate-stage piece of steel , of a size comparable to many traditional iron blooms, that was ready to be further worked into billet . The onset of the Iron Age in most parts of
427-511: A higher concentration of hydroxide (OH-) in ground water . This alkalinity promotes the mineralization of dissolved CO 2 (from the atmosphere) to produce calcite (CaCO 3 ), which can accumulate to as thick as 20 cm. This can also lead to the dissolution of other metals in slag, such as iron (Fe), manganese (Mn), nickel (Ni), and molybdenum (Mo), which become insoluble in water and mobile as particulate matter . The most effective method to detoxify alkaline ground water discharge
488-431: A highly abrasive dust that has caused car parts to wear at significantly greater than normal rates. Dissolution of slags generate alkalinity that can be used to precipitate out metals, sulfates, and excess nutrients (nitrogen and phosphorus) in wastewater treatment. Similarly, ferrous slags have been used as soil conditioners to re-balance soil pH and fertilizers as sources of calcium and magnesium. Because of
549-405: A natural draft effect (into the range of 200 cm tall), and increasing bloom sizes into the range of 10–15 kg. Contemporary experimenters had routinely made blooms using Northern European-derived "short-shaft" furnaces with blown air supplies in the 5–10 kg range The use of waterwheels , spreading around the turn of the first millennium and used to power more massive bellows, allowed
610-450: A noncarburized bloom, this pound, fold, and weld process resulted in a more homogeneous product and removed much of the slag. The process had to be repeated up to 15 times when high-quality steel was needed, as for a sword. The alternative was to carburize the surface of a finished product. Each welding's heat oxidises some carbon, so the master smith had to make sure enough carbon was in the starting mixture. In England and Wales, despite
671-413: A series of experiments testing the reactivity of a specific slag material (i.e., dissolution ) or using the topological constraint theory (TCT) to account for its complex chemical network. Slags are transported along with slag tailings to "slag dumps", where they are exposed to weathering, with the possibility of leaching of toxic elements and hyperalkaline runoffs into the soil and water, endangering
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#1732772827241732-416: A spongy mass referred to as the bloom . Because the bloom is typically porous , and its open spaces can be full of slag, the extracted mass must be beaten with heavy hammers to both compress voids and drive out any molten slag remaining. This process may require several additional heating and compaction cycles, working at high 'welding' temperatures. Iron treated this way is said to be wrought (worked), and
793-425: A wind-driven furnace was found in an excavation site. Such furnaces were powered by the monsoon winds and have been dated to 300 BC using radiocarbon-dating techniques. These ancient Lankan furnaces might have produced the best-quality steel for legendary Damascus swords as referred in earlier Syrian records. Field trials using replica furnaces confirmed that this furnace type uses a wind-based air-supply principle that
854-896: Is designed to minimize iron loss, which gives out the significant amount of iron, following by oxides of calcium , silicon , magnesium , and aluminium. As the slag is cooled down by water, several chemical reactions from a temperature of around 2,600 °F (1,430 °C) (such as oxidization ) take place within the slag. Based on a case study at the Hopewell National Historical Site in Berks and Chester counties, Pennsylvania , US, ferrous slag usually contains lower concentration of various types of trace elements than non-ferrous slag . However, some of them, such as arsenic (As), iron, and manganese , can accumulate in groundwater and surface water to levels that can exceed environmental guidelines. Non-ferrous slag
915-539: Is distinct from either forced or natural draught, and show also that they are capable of producing high-carbon steel. Wrought iron was used in the construction of monuments such as the iron pillar of Delhi , built in the third century AD during the Gupta Empire . The latter was built using a towering series of disc-shaped iron blooms. Similar to China, high-carbon steel was eventually used in India, although cast iron
976-685: Is located in Fengxiang County , Shaanxi (a museum exists on the site today). The earliest records of bloomery-type furnaces in East Africa are discoveries of smelted iron and carbon in Nubia in ancient Sudan dated at least to the seventh to the sixth century BC. The ancient bloomeries that produced metal tools for the Nubians and Kushites produced a surplus for sale. All traditional sub-Saharan African iron-smelting processes are variants of
1037-467: Is produced from non-ferrous metals of natural ores. Non-ferrous slag can be characterized into copper, lead, and zinc slags due to the ores' compositions, and they have more potential to impact the environment negatively than ferrous slag. The smelting of copper, lead and bauxite in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags. Copper slag,
1098-526: Is slags) are generated per tonne of steel produced. Slag is usually a mixture of metal oxides and silicon dioxide . However, slags can contain metal sulfides and elemental metals. It is important to note, the oxide form may or may not be present once the molten slag solidifies and forms amorphous and crystalline components. The major components of these slags include the oxides of calcium , magnesium , silicon , iron, and aluminium, with lesser amounts of manganese , phosphorus , and others depending on
1159-439: Is the preparation of the charcoal and the iron ore. Charcoal is nearly pure carbon , which, when burned, both produces the high temperature needed for the smelting process and provides the carbon monoxide needed for reduction of the metal. The ore is broken into small pieces and usually roasted in a fire, to make rock-based ores easier to break up, bake out some impurities, and (to a lesser extent) to remove any moisture in
1220-593: Is used in the manufacture of high-performance concretes, especially those used in the construction of bridges and coastal features, where its low permeability and greater resistance to chlorides and sulfates can help to reduce corrosive action and deterioration of the structure. Slag can also be used to create fibers used as an insulation material called slag wool . Slag is also used as aggregate in asphalt concrete for paving roads . A 2022 study in Finland found that road surfaces containing ferrochrome slag release
1281-658: The Nsukka region of southeast Nigeria in what is now Igboland . The site of Gbabiri, in the Central African Republic , has also yielded evidence of iron metallurgy, from a reduction furnace and blacksmith workshop, with earliest dates of 896–773 and 907–796 BC, respectively. During a hydroelectric plant project, in the southern foothills of the Central Highlands, Samanalawewa, in Sri Lanka ,
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#17327728272411342-667: The alumina and silica separated from the metal, and assisting in the removal of sulfur and phosphorus from the steel. As a co-product of steelmaking , slag is typically produced either through the blast furnace – oxygen converter route or the electric arc furnace – ladle furnace route. To flux the silica produced during steelmaking, limestone and/or dolomite are added, as well as other types of slag conditioners such as calcium aluminate or fluorspar . There are three types of slag: ferrous , ferroalloy , non-ferrous slags, which are produced through different smelting processes. Ferrous slags are produced in different stages of
1403-592: The missions , encomiendas , and pueblos . As part of the Franciscan Spanish missions in Alta California , the "Catalan forges" at Mission San Juan Capistrano from the 1790s are the oldest existing facilities of their kind in the present day state of California . The bloomeries' sign proclaims the site as being "part of Orange County 's first industrial complex". The archaeology at Jamestown Virginia ( circa 1610–1615 ) had recovered
1464-598: The temperature control of the smelting, and minimizing any re-oxidation of the final liquid metal product before the molten metal is removed from the furnace and used to make solid metal. In some smelting processes, such as ilmenite smelting to produce titanium dioxide , the slag can be the valuable product. During the Bronze Age of the Mediterranean area there were a vast number of differential metallurgical processes in use. A slag by-product of such workings
1525-625: The 12th century. The oldest bloomery in Sweden, also found in the same area, has been carbon-14 dated to 700 BCE. Bloomeries survived in Spain and southern France as Catalan forges into the mid-19th century, and in Austria as the Stückofen to 1775. Iron smelting was unknown in pre-Columbian America . Excavations at L'Anse aux Meadows , Newfoundland, have found considerable evidence for
1586-494: The EAF process can contain toxic metals, which can be hazardous to human and environmental health. Due to the large demand for ferrous, ferralloy, and non-ferrous materials, slag production has increased throughout the years despite recycling (most notably in the iron and steelmaking industries) and upcycling efforts. The World Steel Association (WSA) estimates that 600 kg of co-materials (co-products and by-products)(about 90 wt%
1647-485: The West, iron began to be used around 1200 BC. China has long been considered the exception to the general use of bloomeries. The Chinese are thought to have skipped the bloomery process completely, starting with the blast furnace and the finery forge to produce wrought iron; by the fifth century BC, metalworkers in the southern state of Wu had invented the blast furnace and the means to both cast iron and to decarburize
1708-803: The arrival of the blast furnace in the Weald in about 1491, bloomery forges, probably using waterpower for the hammer and the bellows, were operating in the West Midlands region beyond 1580. In Furness and Cumberland , they operated into the early 17th century and the last one in England (near Garstang ) did not close until about 1770. One of the oldest-known blast furnaces in Europe has been found in Lapphyttan in Sweden , carbon-14 dated to be from
1769-731: The bloomery process. There is considerable discussion about the origins of iron metallurgy in Africa . Smelting in bloomery type furnaces in West Africa and forging of tools appeared in the Nok culture of central Nigeria by at least 550 BC and possibly several centuries earlier. Also, evidence indicates iron smelting with bloomery-style furnaces dated to 750 BC in Opi (Augustin Holl 2009) and Lejja dated to 2,000 BC (Pamela Eze-Uzomaka 2009), both sites in
1830-409: The bloomery to become larger and hotter, with associated trip hammers allowing the consolidation forging of the larger blooms created. Progressively larger bloomeries were constructed in the late 14th century, with a capacity of about 15 kg on average, though exceptions did exist. European average bloom sizes quickly rose to 300 kg, where they levelled off until the demise of the bloomery. As
1891-474: The bottom of the furnace, where they combine with molten slag, often consisting of fayalite , a compound of silicon , oxygen , and iron mixed with other impurities from the ore. The hot liquid slag, running to the bottom of the furnace, cools against the base and lower side walls of the furnace, effectively forming a bowl still containing fluid slag. As the individual iron particles form, they fall into this bowl and sinter together under their own weight, forming
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1952-415: The bottom, one or more pipes (made of clay or metal) enter through the side walls. These pipes, called tuyeres , allow air to enter the furnace, either by natural draught or forced with bellows or a trompe . An opening at the bottom of the bloomery may be used to remove the bloom, or the bloomery can be tipped over and the bloom removed from the top. The first step taken before the bloomery can be used
2013-443: The carbon-rich pig iron produced in a blast furnace to a low-carbon, wrought iron-like material. Recent evidence, however, shows that bloomeries were used earlier in ancient China , migrating in from the west as early as 800 BC, before being supplanted by the locally developed blast furnace. Supporting this theory was the discovery of "more than ten" iron-digging implements found in the tomb of Duke Jing of Qin (d. 537 BCE), whose tomb
2074-463: The context of the iron industry, the term manufacture is best reserved for this final stage. The notable ironworks of the world are described here by country. See above for the largest producers and the notable ironworks in the alphabetical order. The largest Japanese steel companies' main works are as follows: Bloomery A bloomery is a type of metallurgical furnace once used widely for smelting iron from its oxides . The bloomery
2135-413: The following: The mills operating converters of any type are better called steelworks, ironworks referring to former processes, like puddling . After bar iron had been produced in a finery forge or in the forge train of a rolling mill, it might undergo further processes in one of the following: Most of these processes did not produce finished goods. Further processes were often manual, including In
2196-624: The iron and steelmaking processes resulting in varying physiochemical properties. Additionally, the rate of cooling of the slag material affects its degree of crystallinity further diversifying its range of properties. For example, slow cooled blast furnace slags (or air-cooled slags) tend have more crystalline phases than quenched blast furnace slags ( ground granulated blast furnace slags ) making it denser and better suited as an aggregate. It may also have higher free calcium oxide and magnesium oxide content, which are often converted to its hydrated forms if excessive volume expansions are not desired. On
2257-519: The iron content of the primary bog iron ore found in the purpose built 'furnace hut' with the iron remaining in that slag, an estimated 3 kg iron bloom was produced. At a yield of at best 20% from what is a good iron rich ore, this suggests the workers processing the ore had not been particularly skilled. This supports the idea that iron processing knowledge was widespread and not restricted to major centers of trade and commerce. Archaeologists also found 98 nail, and importantly, ship rivet fragments, at
2318-470: The ironworks to provide jobs and housing. As the ironworks closed down (or was industrialised) these villages quite often went into decline and experienced negative economic growth. Ironworks is used as an omnibus term covering works undertaking one or more iron-producing processes. Such processes or species of ironworks where they were undertaken include the following: From the 1850s, pig iron might be partly decarburised to produce mild steel using one of
2379-429: The later strength gain of concrete. This leads to concrete with reduced permeability and better durability. Careful consideration of the slag type used is required, as the high calcium oxide and magnesium oxide content can lead to excessive volume expansion and cracking in concrete. These hydraulic properties have also been used for soil stabilization in roads and railroad constructions . Granulated blast furnace slag
2440-513: The local ecological communities. Leaching concerns are typically around non-ferrous or base metal slags, which tend to have higher concentrations of toxic elements. However, ferrous and ferroalloy slags may also have them, which raises concerns about highly weathered slag dumps and upcycled materials. Dissolution of slags can produce highly alkaline groundwater with pH values above 12. The calcium silicates (CaSiO 4 ) in slags react with water to produce calcium hydroxide ions that leads to
2501-461: The molten metal and can be removed. Slag is the collection of compounds that are removed. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities and protecting the furnace refractory lining from excessive wear. In this case, the slag is termed synthetic . A good example is steelmaking slag: quicklime (CaO) and magnesite (MgCO 3 ) are introduced for refractory protection, neutralizing
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2562-526: The ore. Any large impurities (as silica) in the ore can be removed as it is crushed. The desired particle size depends primarily on which of several ore types may be available, which will also have a relationship to the layout and operation of the furnace, of which a number of regional, historic/traditional forms exist. Natural iron ores can vary considerably in oxide form ( Fe 2 O 3 / Fe 3 O 4 / FeO(OH) ), and importantly in relative iron content. Since slag from previous blooms may have
2623-653: The other hand, water quenched blast furnace slags have greater amorphous phases giving it latent hydraulic properties (as discovered by Emil Langen in 1862) similar to Portland cement . During the process of smelting iron, ferrous slag is created, but dominated by calcium and silicon compositions. Through this process, ferrous slag can be broken down into blast furnace slag (produced from iron oxides of molten iron), then steel slag (forms when steel scrap and molten iron combined). The major phases of ferrous slag contain calcium-rich olivine -group silicates and melilite -group silicates. Slag from steel mills in ferrous smelting
2684-439: The plastic, and concrete industries and leached for metals to be used in the electronic industries. However, high physical and chemical variability across different types of slags results in performance and yield inconsistencies. Moreover, stoichiometric -based calculation of the carbonation potential can lead to overestimation that can further obfuscate the material's true potential. To this end, some have proposed performing
2745-476: The processing of bog iron and the production of iron in a bloomery by the Norse. The cluster of Viking Age ( c. 1000 –1022 AD) at L'Anse aux Meadows are situated on a raised marine terrace, between a sedge peat bog and the ocean. Estimates from the smaller amount of slag recovered archaeologically suggest 15 kg of slag was produced during what appears to have been a single smelting attempt. By comparing
2806-594: The remains of a simple short-shaft bloomery furnace, likely intended as yet another "resource test" like the one in Vinland much earlier. The English settlers of the Thirteen Colonies were prevented by law from manufacture; for a time, the British sought to situate most of the skilled artisanry at domestic locations. In fact, this was one of the problems that led to the revolution. The Falling Creek Ironworks
2867-418: The resulting iron, with reduced amounts of slag, is called wrought iron or bar iron. Because of the creation process, individual blooms can often have differing carbon contents between the original top and bottom surfaces, differences that will also be somewhat blended together through the flattening, folding, and hammer-welding sequences. Intentionally producing blooms that are coated in steel (i.e. iron with
2928-552: The site as well as considerable evidence for woodworking – which points to boat or possibly ship repairs being undertaken at the site. (An important consideration remains that a potential 3 kg raw bloom most certainly does not make enough refined bar to manufacture the 3 kg of recovered nails and rivets.) In the Spanish colonization of the Americas , bloomeries or "Catalan forges" were part of "self-sufficiency" at some of
2989-713: The slowly released phosphate content in phosphorus -containing slag, and because of its liming effect, it is valued as fertilizer in gardens and farms in steel making areas. However, the most important application is construction. Slags have one of the highest carbonation potential among the industrial alkaline waste due their high calcium oxide and magnesium oxide content, inspiring further studies to test its feasibility in CO 2 capture and storage ( CCS ) methods (e.g., direct aqueous sequestration, dry gas-solid carbonation among others). Across these CCS methods, slags can be transformed into precipitated calcium carbonates to be used in
3050-404: The smelt progresses. Overall, a typical ratio of total charcoal to ore added is in a roughly one-to-one ratio. Inside the furnace, carbon monoxide from the incomplete combustion of the charcoal reduces the iron oxides in the ore to metallic iron without melting the ore; this allows the bloomery to operate at lower temperatures than the melting temperature of the ore. As the desired product of
3111-403: The specifics of the raw materials used. Furthermore, slag can be classified based on the abundance of iron among other major components. In nature, iron, copper, lead, nickel , and other metals are found in impure states called ores , often oxidized and mixed in with silicates of other metals. During smelting, when the ore is exposed to high temperatures, these impurities are separated from
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#17327728272413172-572: The term siderurgy is also occasionally used. This is derived from the Greek words sideros - iron and ergon or ergos - work. This is an unusual term in English, and it is best regarded as an anglicisation of a term used in French , Spanish , and other Romance languages . Historically, it is common that a community was built around the ironworks where the people living there were dependent on
3233-472: The waste product of smelting copper ores, was studied in an abandoned Penn Mine in California, US. For six to eight months per year, this region is flooded and becomes a reservoir for drinking water and irrigation . Samples collected from the reservoir showed the higher concentration of cadmium (Cd) and lead (Pb) that exceeded regulatory guidelines. Slags can serve other purposes, such as assisting in
3294-521: The world coincides with the first widespread use of the bloomery. While earlier examples of iron are found, their high nickel content indicates that this is meteoric iron . Other early samples of iron may have been produced by accidental introduction of iron ore in copper-smelting operations. Iron appears to have been smelted in the Middle East as early as 3000 BC, but coppersmiths, not being familiar with iron, did not put it to use until much later. In
3355-423: Was a colorful, glassy material found on the surfaces of slag from ancient copper foundries. It was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. It was also ground into powder to add to glazes for use in ceramics. Some of the earliest such uses for the by-products of slag have been found in ancient Egypt . Historically, the re-smelting of iron ore slag
3416-439: Was also used as an aggregate and had begun being integrated into the cement industry as a geopolymer . Today, ground granulated blast furnace slags are used in combination with Portland cement to create " slag cement ". Granulated blast furnace slags react with portlandite ( Ca(OH) 2 ), which is formed during cement hydration, via the pozzolanic reaction to produce cementitious properties that primarily contribute to
3477-442: Was common practice, as improved smelting techniques permitted greater iron yields—in some cases exceeding that which was originally achieved. During the early 20th century, iron ore slag was also ground to a powder and used to make agate glass , also known as slag glass. Use of slags in the construction industry dates back to the 1800s, where blast furnace slags were used to build roads and railroad ballast. During this time, it
3538-512: Was considered a waste product detracting from the largest bloomeries' yield, and early blast furnaces , identical in construction, but dedicated to the production of molten iron, were not built until the 14th century. Bloomery type furnaces typically produced a range of iron products from very low-carbon iron to steel containing around 0.2–1.5% carbon. The master smith had to select pieces of low-carbon iron, carburize them, and pattern-weld them together to make steel sheets. Even when applied to
3599-427: Was not used for architecture until modern times. Early European bloomeries were relatively small, primarily due to the mechanical limits of human-powered bellows and the amount of force possible to apply with hand-driven sledge hammers. Those known archaeologically from the pre-Roman Iron Age tend to be in the 2 kg range, produced in low shaft furnaces. Roman-era production often used furnaces tall enough to create
3660-455: Was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a bloom . The mix of slag and iron in the bloom, termed sponge iron , is usually consolidated and further forged into wrought iron . Blast furnaces , which produce pig iron , have largely superseded bloomeries. A bloomery consists of a pit or chimney with heat-resistant walls made of earth, clay , or stone . Near
3721-545: Was the first in the United States. The Neabsco Iron Works is an example of the early Virginian effort to form a workable American industry. The earliest iron forge in colonial Pennsylvania was Thomas Rutter 's bloomery near Pottstown , founded in 1716. In the Adirondacks , New York, new bloomeries using the hot blast technique were built in the 19th century. Slag The general term slag may be
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