Finery forge

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Hearth (left) and trip hammer (centre) in a finery forge. In the back room (right) is a large pile of charcoal. PSM V38 D183 A forge trip hammer.jpg
Hearth (left) and trip hammer (centre) in a finery forge. In the back room (right) is a large pile of charcoal.

A finery forge is a forge used to produce wrought iron from pig iron by decarburization in a process called "fining" which involved liquifying cast iron in a fining hearth and removing carbon from the molten cast iron through oxidation. [1] Finery forges were used as early as the 3rd century BC in China. [1] The finery forge process was replaced by the puddling process and the roller mill, both developed by Henry Cort in 1783–4, but not becoming widespread until after 1800. [2]

Contents

History

A finery forge was used to refine wrought iron at least by the 3rd century BC in ancient China, based on the earliest archaeological specimens of cast and pig iron fined into wrought iron and steel found at the early Han Dynasty (202 BC – 220 AD) site at Tieshengguo. [1] Pigott speculates that the finery forge existed in the previous Warring States period (403–221 BC), because of the wrought iron items from China dating to that period and there was no documented evidence of the bloomery ever being used in China. [1] Wagner writes that in addition to the Han Dynasty hearths believed to be fining hearths, there is also pictoral evidence of the fining hearth from a Shandong tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist text Taiping Jing . [3]

In Europe, the concept of the finery forge may have been evident as early as the 13th century. [4] However, it was perhaps not capable of being used to fashion plate armor until the 15th century, as described in conjunction with the waterwheel-powered blast furnace by the Florentine Italian engineer Antonio Averlino (c. 1400 - 1469). [5] The finery forge process began to be replaced in Europe from the late 18th century by others, of which puddling was the most successful, though some continued in use through the mid-19th century. The new methods used mineral fuel (coal or coke), and freed the iron industry from its dependence on wood to make charcoal.

Types

Interior of the preserved Walloon forge in Osterbybruk, Uppland Vallonsmedjan interor.jpg
Interior of the preserved Walloon forge in Österbybruk, Uppland
Exterior of the remnants of a Basque forge Bolunburu burdinola.jpg
Exterior of the remnants of a Basque forge

There were several types of finery forges.

German forge

The dominant type in Sweden was the German forge, which had a single hearth that was used for all processes.

Walloon forge

In Swedish Uppland north of Stockholm and certain adjacent provinces, another kind known as the Walloon forge was used, mainly for the production of a particularly pure kind of iron known as oregrounds iron, which was exported to England to make blister steel. Its purity depended on the use of ore from the Dannemora mine. The Walloon forge was virtually the only kind used in Great Britain.

The forge had two kinds of hearths, the finery to finish the product and the chafery to reheat the bloom that was the raw material of the process.

Lancashire forge

Process

In the finery, a workman known as the "finer" remelted pig iron so as to oxidise the carbon (and silicon). This produced a lump of iron (with some slag) known as a bloom. This was consolidated using a water-powered hammer (see trip hammer) and returned to the finery.

The next stages were undertaken by the "hammerman", who in some iron-making areas such as South Yorkshire was also known as the "stringsmith", who heated his iron in a string-furnace. Because the bloom is highly porous, and its open spaces are full of slag, the hammerman's or stringsmith's tasks were to beat (work) the heated bloom with a hammer to drive the molten slag out of it, and then to draw the product out into a bar to produce what was known as anconies or bar iron. In order to do this, he had to reheat the iron, for which he used the chafery. The fuel used in the finery had to be charcoal (later coke), as impurities in any mineral fuel would affect the quality of the iron.

Slag

The waste product was allowed to cool in the hearth and removed as a "mosser". [6] In the Furness district they were often left as the capstone of a wall, particularly near Spark Bridge and Nibthwaite forges.

Mosser found near Newland Furnace Mosser 01.jpg
Mosser found near Newland Furnace
Mosser found near Newland Furnace Mosser, reverse side.jpg
Mosser found near Newland Furnace

Related Research Articles

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Smelting Use of heat and a reducing agent to extract metal from ore

Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal base behind. The reducing agent is commonly a fossil fuel source of carbon, such as coke—or, in earlier times, charcoal. The oxygen in the ore binds to carbon at high temperatures due to the lower potential energy of the bonds in carbon dioxide. Smelting most prominently takes place in a blast furnace to produce pig iron, which is converted into steel.

Pig iron Iron alloy

Pig iron is an intermediate product of the iron industry in the production of steel, also known as crude iron, which is obtained by smelting iron ore in a blast furnace. Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle and not useful directly as a material except for limited applications.

Wrought iron Iron alloy with a very low carbon content

Wrought iron is an iron alloy with a very low carbon content in contrast to that of cast iron. It is a semi-fused mass of iron with fibrous slag inclusions, which gives it a "grain" resembling wood that is visible when it is etched or bent to the point of failure. Wrought iron is tough, malleable, ductile, corrosion resistant, and easily welded.

Steelmaking Process for producing steel from iron ore and scrap

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. Limiting dissolved gases such as nitrogen and oxygen and entrained impurities in the steel is also important to ensure the quality of the products cast from the liquid steel.

Blast furnace Type of metallurgical furnace used for smelting to produce industrial metals

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.

Cementation process

The cementation process is an obsolete technology for making steel by carburization of iron. Unlike modern steelmaking, it increased the amount of carbon in the iron. It was apparently developed before the 17th century. Derwentcote Steel Furnace, built in 1720, is the earliest surviving example of a cementation furnace. Another example in the UK is the cementation furnace in Doncaster Street, Sheffield.

Wealden iron industry

The Wealden iron industry was located in the Weald of south-eastern England. It was formerly an important industry, producing a large proportion of the bar iron made in England in the 16th century and most British cannon until about 1770. Ironmaking in the Weald used ironstone from various clay beds, and was fuelled by charcoal made from trees in the heavily wooded landscape. The industry in the Weald declined when ironmaking began to be fuelled by coke made from coal, which does not occur accessibly in the area.

Open hearth furnace

Open-hearth furnaces are one of several kinds of furnace in which excess carbon and other impurities are burnt out of pig iron to produce steel. Since steel is difficult to manufacture owing to its high melting point, normal fuels and furnaces were insufficient and the open-hearth furnace was developed to overcome this difficulty. Compared to Bessemer steel, 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.

Bloomery Type of furnace once used widely for smelting iron from its oxides

A bloomery is a type of furnace once used widely for smelting iron from its oxides. The bloomery 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.

Reverberatory furnace metallurgical furnace

A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. The term reverberation is used here in a generic sense of rebounding or reflecting, not in the acoustic sense of echoing.

Ironworks

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.

Puddling (metallurgy)

Puddling is a step in the manufacture of high-grade iron in a crucible or furnace. It was invented in Great Britain during the Industrial Revolution. The molten pig iron was stirred in a reverberatory furnace, in an oxidizing environment, resulting in wrought iron. It was one of the most important processes of making the first appreciable volumes of valuable and useful bar iron without the use of charcoal. Eventually, the furnace would be used to make small quantities of specialty steels.

Direct reduced iron

Direct reduced iron (DRI), also called sponge iron, is produced from the direct reduction of iron ore to iron by a reducing gas or elemental carbon produced from natural gas or coal. Many ores are suitable for direct reduction.

Osmond process

Osmond iron was wrought iron made by a particular process. This is associated with the first European production of cast iron in furnaces such as Lapphyttan in Sweden.

Walloon forge

A Walloon forge is a type of finery forge that decarbonizes pig iron into wrought iron.

Ferrous metallurgy

Ferrous metallurgy is the metallurgy of iron and alloys. It began far back in prehistory. The earliest surviving iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC iron was being produced from iron ores from at least Greece to India, and more controversially Sub-Saharan Africa. The use of wrought iron was known by the 1st millennium BC, and its spread marked the Iron Age. During the medieval period, means were found in Europe of producing wrought iron from cast iron using finery forges. For all these processes, charcoal was required as fuel.

Cornwall Iron Furnace United States historic place

Cornwall Iron Furnace is a designated National Historic Landmark that is administered by the Pennsylvania Historical and Museum Commission in Cornwall, Lebanon County, Pennsylvania in the United States. The furnace was a leading Pennsylvania iron producer from 1742 until it was shut down in 1883. The furnaces, support buildings and surrounding community have been preserved as a historical site and museum, providing a glimpse into Lebanon County's industrial past. The site is the only intact charcoal-burning iron blast furnace in its original plantation in the western hemisphere. Established by Peter Grubb in 1742, Cornwall Furnace was operated during the Revolution by his sons Curtis and Peter Jr. who were major arms providers to George Washington. Robert Coleman acquired Cornwall Furnace after the Revolution and became Pennsylvania's first millionaire. Ownership of the furnace and its surroundings was transferred to the Commonwealth of Pennsylvania in 1932.

Lancashire hearth

The Lancashire hearth was used to fine pig iron, removing carbon to produce wrought iron.

Metallurgical furnace Device used to heat and munipuliate metals

A metallurgicalfurnace, more commonly referred to as a furnace, is a device used to heat and melt metal ore to remove gangue, primarily in iron and steel production. The heat energy to fuel a furnace may be supplied directly by fuel combustion, by electricity such as the electric arc furnace, or through induction heating in induction furnaces. There are several different types of furnaces used in metallurgy to work with specific metal and ores.

References

  1. 1 2 3 4 Pigott, Vincent C. (1999). The Archaeometallurgy of the Asian Old World. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology. ISBN   0-924171-34-0, p. 186-187.
  2. Ayres, Robert (1989). "Technological Transformations and Long Waves" (PDF): 12.Cite journal requires |journal= (help)
  3. Wagner, Donald B. (2001). The State and the Iron Industry in Han China. Copenhagen: Nordic Institute of Asian Studies Publishing. ISBN   87-87062-83-6, pp. 80–83.
  4. Williams, Alan R. (2003). The Knight and the Blast Furnace: a History of the Metallurgy of Armor in the Middle Ages & the Early Modern Period. Leiden: Brill. ISBN   9789004124981, pp 883.
  5. Williams, Alan R. (2003). The Knight and the Blast Furnace: a History of the Metallurgy of Armor in the Middle Ages & the Early Modern Period. Leiden: Brill. ISBN   9789004124981, pp 883-84.
  6. "Falling Creek Ironworks Park | Chesterfield County, VA". www.chesterfield.gov.

Sources