Bessemer process was the first inexpensive industrial process for
the mass production of steel from molten pig iron before the
development of the open hearth furnace. The key principle is removal
of impurities from the iron by oxidation with air being blown through
the molten iron. The oxidation also raises the temperature of the iron
mass and keeps it molten.
Related decarburizing with air processes had been used outside Europe
for hundreds of years, but not on an industrial scale. One such
process has existed since the 11th century in East Asia, where the
Shen Kuo of that era described its use in the Chinese iron and
steel industry. In the 17th century, accounts by European
travelers detailed its possible use by the Japanese.
The modern process is named after its inventor, the Englishman Henry
Bessemer, who took out a patent on the process in 1856. The process
was said to be independently discovered in 1851 by the American
inventor William Kelly, though there is little to back up this
The process using a basic refractory lining is known as the "basic
Bessemer process" or "Gilchrist–Thomas process" after the English
Percy Gilchrist and Sidney Gilchrist Thomas.
1.2 Managing the process
2 Predecessor processes
Bessemer process in the United States
8 See also
10 External links
Bessemer converter components.
The blowing of air through the molten pig iron introduces oxygen into
the melt which results in oxidation, removing impurities found in the
pig iron, such as silicon, manganese, and carbon in the form of
oxides. These oxides either escape as gas or form a solid slag. The
refractory lining of the converter also plays a role in the conversion
— clay linings are used when there is little phosphorus in the raw
material - this is known as the acid Bessemer process. When the
phosphorus content is high, dolomite, or sometimes magnesite, linings
are used in the alkaline Bessemer limestone process. These are also
known as Gilchrist-Thomas converters, after their inventors, Percy
Gilchrist and Sidney Gilchrist Thomas. In order to produce steel with
desired properties, additives such as spiegeleisen (a ferromanganese
alloy), can be added to the molten steel once the impurities have been
Managing the process
When the required steel had been formed, it was poured into ladles and
then transferred into moulds while the lighter slag was left behind.
The conversion process, called the "blow", was completed in
approximately 20 minutes. During this period the progress of the
oxidation of the impurities was judged by the appearance of the flame
issuing from the mouth of the converter. The modern use of
photoelectric methods of recording the characteristics of the flame
greatly aided the blower in controlling final product quality. After
the blow, the liquid metal was recarburized to the desired point and
other alloying materials were added, depending on the desired product.
A Bessemer converter could treat a "heat" (batch of hot metal) of 5 to
30 tons at a time. They were usually operated in pairs, one being
blown while another was being filled or tapped.
Bessemer converter at Högbo Bruk, Sandviken.
Before the Bessemer process, Western Europe and the United States
relied on the puddling process to reduce the carbon content of white
cast iron (refined pig iron), converting it to wrought iron. It was
possible to make low-quality puddled steel, but the process was
difficult to control and quality varied. High-quality steel was made
by the reverse process of adding carbon to carbon-free wrought iron,
usually imported from Sweden. The manufacturing process, called the
cementation process, consisted of heating bars of wrought iron
together with charcoal for periods of up to a week in a long stone
box. This produced blister steel. The blister steel was put in a
crucible with wrought iron and melted, producing crucible steel. Up to
3 tons of expensive coke was burnt for each ton of steel produced.
Such steel when rolled into bars was sold at £50 to £60
(approximately £3,390 to £4,070 in 2008) a long ton. The most
difficult and work-intensive part of the process, however, was the
production of wrought iron done in finery forges in Sweden.
This process was refined in the 18th century with the introduction of
Benjamin Huntsman's crucible steel-making techniques, which added an
additional three hours firing time and required additional large
quantities of coke. In making crucible steel, the blister steel bars
were broken into pieces and melted in small crucibles, each containing
20 kg or so. This produced higher quality crucible steel but
increased the cost. The
Bessemer process reduced the time needed to
make steel of this quality to about half an hour while requiring only
the coke needed initially to melt the pig iron. The earliest Bessemer
converters produced steel for £7 a long ton, although it initially
sold for around £40 a ton.
Bessemer converter, Kelham Island Museum,
Sheffield, England (2010).
A system akin to the
Bessemer process has existed since the 11th
century in East Asia. Economic historian Robert Hartwell writes
that the Chinese of the
Song Dynasty innovated a "partial
decarbonization" method of repeated forging of cast iron under a cold
Joseph Needham and historian of metallurgy
Theodore A. Wertime have described the method as a predecessor to the
Bessemer process of making steel. This process was first
described by the prolific scholar and polymath government official
Shen Kuo (1031–1095) in 1075, when he visited Cizhou. Hartwell
states that perhaps the earliest center where this was practiced was
the great iron-production district along the Henan-
Hebei border during
the 11th century.
In the 15th century the finery process, another process which shares
the air-blowing principle with the Bessemer process, was developed in
Europe. In 1740
Benjamin Huntsman developed the crucible technique for
steel manufacture, at his workshop in the district of Handsworth in
Sheffield. This process had an enormous impact on the quantity and
quality of steel production, but it was unrelated to the Bessemer-type
process employing decarburization.
Johan Albrecht de Mandelslo
Johan Albrecht de Mandelslo described the Japanese use of the Bessemer
The Japanese may have made use of the Bessemer process, which was
observed by European travelers in the 17th century. The adventurer
Johan Albrecht de Mandelslo
Johan Albrecht de Mandelslo describes the process in a book published
in English in 1669. He writes, "They have, among others, particular
invention for the melting of iron, without the using of fire, casting
it into a tun done about on the inside without about half a foot of
earth, where they keep it with continual blowing, take it out by
ladles full, to give it what form they please." According to historian
Donald Wagner, Madelslo did not personally visit Japan, so his
description of the process is likely derived from accounts of other
Europeans who had traveled to Japan. Wagner believes that the Japanese
process may have been similar to the Bessemer process, but cautions
that alternative explanations are also plausible.
William Kelly may have independently discovered the process before
In the early 1850s, the American inventor William Kelly experimented
with a method similar to the Bessemer process. Wagner writes that
Kelly may have been inspired by techniques introduced by Chinese
ironworkers hired by Kelly in 1854. When Bessemer's patent for the
process was reported by Scientific American, Kelly responded by
writing a letter to the magazine. In the letter, Kelly states that he
had previously experimented with the process and claimed that Bessemer
knew of Kelly's discovery. He wrote that "I have reason to believe my
discovery was known in England three or four years ago, as a number of
English puddlers visited this place to see my new process. Several of
them have since returned to England and may have spoken of my
Henry Bessemer described the origin of his invention in his
autobiography written in 1890. During the outbreak of the Crimean War,
many English industrialists and inventors became interested in
military technology. According to Bessemer, his invention was inspired
by a conversation with
Napoleon III in 1854 pertaining to the steel
required for better artillery. Bessemer claimed that it "was the spark
which kindled one of the greatest revolutions that the present century
had to record, for during my solitary ride in a cab that night from
Vincennes to Paris, I made up my mind to try what I could to improve
the quality of iron in the manufacture of guns." At the time steel
was used to make only small items like cutlery and tools, but was too
expensive for cannons. Starting in January 1855 he began working on a
way to produce steel in the massive quantities required for artillery
and by October he filed his first patent related to the Bessemer
process. He patented the method a year later in 1856.
According to his autobiography Bessemer was working with an ordinary
reverberatory furnace but during a test, some pieces of pig iron were
jostled off the side of the ladle, and were left above the ladle in
the furnace's heat. When Bessemer went to push them into the ladle, he
found that they were steel shells: the hot air alone had converted the
outsides of the iron pieces to steel. This crucial discovery led him
to completely redesign his furnace so that it would force
high-pressure air through the molten iron using special air pumps.
Intuitively this would seem to be folly because it would cool the
iron. Instead, the oxygen in the forced air ignited silicon and carbon
impurities in the iron, starting a positive feedback loop. As the iron
became hotter, more impurities burned off, making the iron even hotter
and burning off more impurities, producing a batch of hotter, purer,
molten iron, which converts to steel more easily.
Bessemer licensed the patent for his process to four ironmasters, for
a total of £27,000, but the licensees failed to produce the quality
of steel he had promised—it was "rotten hot and rotten cold",
according to his friend, William Clay—and he later bought them
back for £32,500. His plan had been to offer the licenses to one
company in each of several geographic areas, at a royalty price per
ton that included a lower rate on a proportion of their output in
order to encourage production, but not so large a proportion that they
might decide to reduce their selling prices. By this method he hoped
to cause the new process to gain in standing and market share.
He realised that the technical problem was due to impurities in the
iron and concluded that the solution lay in knowing when to turn off
the flow of air in his process so that the impurities were burned off
but just the right amount of carbon remained. However, despite
spending tens of thousands of pounds on experiments, he could not find
the answer. Certain grades of steel are sensitive to the 78%
nitrogen which was part of the air blast passing through the steel.
Bessemer was sued by the patent purchasers who couldn't get it to
work. In the end Bessemer set up his own steel company because he knew
how to do it, even though he could not convey it to his patent users.
Bessemer's company became one of the largest in the world and changed
the face of steel making.
The solution was first discovered by English metallurgist Robert
Forester Mushet, who had carried out thousands of experiments in the
Forest of Dean. His method was to first burn off, as far as possible,
all the impurities and carbon, then reintroduce carbon and manganese
by adding an exact amount of spiegeleisen. This had the effect of
improving the quality of the finished product, increasing its
malleability—its ability to withstand rolling and forging at high
temperatures and making it more suitable for a vast array of
The first company to license the process was the Manchester firm of W
& J Galloway, and they did so before Bessemer announced it at
Cheltenham in 1856. They are not included in his list of the four to
whom he refunded the license fees. However, they subsequently
rescinded their license in 1858 in return for the opportunity to
invest in a partnership with Bessemer and others. This partnership
began to manufacture steel in
Sheffield from 1858, initially using
imported charcoal pig iron from Sweden. This was the first commercial
Sidney Gilchrist Thomas, a Londoner with a Welsh father, was an
industrial chemist who decided to tackle the problem of phosphorus in
iron, which resulted in the production of low grade steel. Believing
that he had discovered a solution, he contacted his cousin, Percy
Gilchrist, who was a chemist at the Blaenavon ironworks. The manager
at the time, Edward Martin, offered Sidney equipment for large-scale
testing and helped him draw up a patent that was taken out in May,
1878. Sidney Gilchrist Thomas's invention consisted of using dolomite
or sometimes limestone linings for the Bessemer converter rather than
clay, and it became known as the 'basic' Bessemer rather than the
'acid' Bessemer process. An additional advantage was that the
processes formed more slag in the converter, and this could be
recovered and used very profitably as a phosphate fertilizer.
Patents of such value did not escape criticism, and invalidity was
urged against them on various grounds.[clarification needed] But
Bessemer was able to maintain them intact without litigation, though
he found it advisable to buy up the rights of one patentee, Robert
In the case of Mushet, he was assisted by the patent being allowed to
lapse in 1859 through non-payment of fees. Mushet's procedure was
not essential and Bessemer proved this in 1865 by exhibiting a series
of steel samples made using his process alone, but the value of the
procedure was shown by its near universal adoption in conjunction with
the Bessemer process. Whether or not Mushet's patents could have been
sustained is not known, but in 1866 Robert Mushet's 16-year-old
daughter travelled to London to confront
Henry Bessemer at his
offices, arguing that Bessemer's success was based on the results of
her father’s work. Bessemer decided to pay Mushet an annual pension
of £300 (equivalent to £26,000 in 2016), a very considerable sum,
which he paid for 25 years.
In 1866, Bessemer also provided finance for Zerah Colburn, the
American locomotive engineer and journalist, to start a new weekly
engineering newspaper called Engineering based in Bedford Street,
London. It was not until many years later that the name of Colburn's
benefactor was revealed. Before Engineering was launched, Colburn,
through the pages of The Engineer, had given support to Bessemer's
work on steel and steelmaking.
Bessemer furnace in operation in Youngstown, Ohio, 1941.
Bessemer process revolutionized steel manufacture by decreasing
its cost, from £40 per long ton to £6–7 per long ton, along with
greatly increasing the scale and speed of production of this vital raw
material. The process also decreased the labor requirements for
steel-making. Before it was introduced, steel was far too expensive to
make bridges or the framework for buildings and thus wrought iron had
been used throughout the Industrial Revolution. After the introduction
of the Bessemer process, steel and wrought iron became similarly
priced, and some users, primarily railroads, turned to steel. Quality
problems, such as brittleness caused by nitrogen in the blowing
air, prevented Bessemer steel from being used for many structural
applications. Open-hearth steel was suitable for structural
Steel greatly improved the productivity of railroads.
lasted ten times longer than iron rails.
Steel rails, which became
heavier as prices fell, could carry heavier locomotives, which could
pull longer trains.
Steel rail cars were longer and were able to
increase the freight to car weight from 1:1 to 2:1.
As early as 1895 in the UK it was being noted that the heyday of the
Bessemer process was over and that the open hearth method
Iron and Coal Trades Review said that it was "in a
semi-moribund condition. Year after year, it has not only ceased to
make progress, but it has absolutely declined." It has been suggested,
both at that time and more recently, that the cause of this was the
lack of trained personnel and investment in technology rather than
anything intrinsic to the process itself. For example, one of the
major causes of the decline of the giant ironmaking company Bolckow
Vaughan of Middlesbrough was its failure to upgrade its
technology. The basic process, the Thomas-Gilchrist process,
remained in use longer, especially in Continental Europe, where iron
ores were of high phosphorus content and the open-hearth process
was not able to remove all phosphorus; almost all inexpensive
construction steel in Germany was produced with this method in the
1950s and 1960s. It was eventually superseded by basic oxygen
Bessemer process in the United States
While visiting Europe to obtain information on shipbuilding, armour,
and armaments from 1862 to 1863,
Alexander Lyman Holley
Alexander Lyman Holley visited
Sheffield works, and expressed interest in licensing the
process for use in the US. Upon returning to the US, Holley met with
noted inventor John Ericsson, who referred Holley to a pair of
businessmen who had helped him build the Civil War ironclad USS
John F. Winslow and John Augustus Griswold. With Winslow and
Griswold's support, Holley returned to England in 1863, and paid
Bessemer £10,000 to license the technology.
The trio began setting up a mill in
Troy, New York
Troy, New York in 1865. The
factory contained a number of Holley's innovations that greatly
improved productivity over Bessemer's factory in Sheffield, and the
owners gave a successful public exhibition in 1867. The Troy factory
attracted the attention of the Pennsylvania Railroad, which wanted to
use the new process to manufacture steel rail. It funded Holley's
second mill as part of its Pennsylvania
Steel subsidiary. Between 1866
and 1877, the partners were able to license a total of 11 Bessemer
One of the investors they attracted was Andrew Carnegie, who saw great
promise in the new steel technology after a visit to Bessemer in 1872,
and saw it as a useful adjunct to his existing businesses, the
Keystone Bridge Company
Keystone Bridge Company and the Union
Iron Works. Holley built the new
steel mill for Carnegie, and continued to improve and refine the
process. The new mill, known as the Edgar Thomson
Steel Works, opened
in 1875, and started the growth of the United States as a major world
William Walker Scranton, manager and owner of the Lackawanna Iron
& Coal Company in Scranton, Pennsylvania, had also investigated
the process in Europe. He built a mill in 1876 using the Bessemer
process for steel rails and quadrupled his production.
In the U.S., commercial steel production using this method stopped in
1968. It was replaced by processes such as the basic oxygen
(Linz-Donawitz) process, which offered better control of final
Bessemer process was so fast (10–20 minutes for a
heat) that it allowed little time for chemical analysis or adjustment
of the alloying elements in the steel. Bessemer converters did not
remove phosphorus efficiently from the molten steel; as low-phosphorus
ores became more expensive, conversion costs increased. The process
permitted only limited amount of scrap steel to be charged, further
increasing costs, especially when scrap was inexpensive. Use of
electric arc furnace technology competed favourably with the Bessemer
process resulting in its obsolescence.
Basic oxygen steelmaking
Basic oxygen steelmaking is essentially an improved version of the
Bessemer process (decarburization by blowing oxygen as gas into the
heat rather than burning the excess carbon away by adding oxygen
carrying substances into the heat). The advantages of pure oxygen
blast over air blast was known to Henry Bessemer, but
the 19th-century technology was not advanced enough to allow for the
production of the large quantities of pure oxygen to make it
economically feasible for use.
Cementation (metallurgy) process
Methods of crucible steel production
Open hearth furnace, the Siemens-Martin process
Open-hearth furnace process
^ Ponting, Clive (2000), World History, A New Perspective, Pimlico,
^ a b c Needham, Joseph (2008). Science and civilisation in China,
Volume 5, Part 7 (1. publ. ed.). Cambridge, UK: Cambridge University
Press. pp. 261–5. ISBN 9780521875660.
^ a b Tanner, Harold (2009). China: A History. Hackett Publishing.
p. 218. ISBN 0-87220-915-6.
^ a b c d e f g Wagner, Donald (2008). Science and Civilisation in
China: Vol. 5, Part 11: Ferrous Metallurgy. Cambridge University
Press. pp. 363–5. ISBN 978-0-521-87566-0.
^ a b c Wagner, Donald (2008). Science and Civilisation in China: Vol.
5, Part 11: Ferrous Metallurgy. Cambridge University Press.
p. 361. ISBN 978-0-521-87566-0.
^ "Bessemer process". Britannica. 2. Encyclopædia Britannica. 2005.
^ Gordon, Robert B. (2001). American Iron, 1607–1900. JHU Press.
pp. 221–. ISBN 978-0-8018-6816-0.
^ "The Beginnings of Cheap
Steel by Philip W. Bishop". Retrieved 23
February 2018 – via www.gutenberg.org.
^ "No. 762: Kelly's Converter". www.uh.edu. Retrieved 23 February
^ Shaping Technology/building Society: Studies in Sociotechnical
Change. MIT Press. pp. 112–. ISBN 978-0-262-26043-5.
^ [permanent dead link]
^ "Purchasing Power of British Pounds from 1264 to Present". 2009.
Retrieved January 14, 2011.
^ a b c Hartwell, Robert (March 1966). "Markets, Technology, and the
Structure of Enterprise in the Development of the Eleventh-Century
Steel Industry". The Journal of Economic History. 26
(1): 54. ISSN 0022-0507. JSTOR 2116001.
^ Wertime, Theodore A. (1962). The coming of the age of steel.
University of Chicago Press.
^ Temple, Robert K.G. (1999). The Genius of China: 3000 years of
science, discovery and invention. London: Prion. p. 49.
^ a b c Erickson, Charlotte (1986) . British industrialists:
steel and hosiery 1850–1950. Cambridge University Press.
pp. 141–142. ISBN 0-566-05141-9.
^ Bessemer, Sir Henry (1905). Sir Henry Bessemer, F.R.S. Offices of
^ Anstis 1997, p. 147.
^ J.E. Gordon, "The new science of strong materials", Penguin books.
^ "Mushet, Robert Forester". Dictionary of National Biography.
London: Smith, Elder & Co. 1885–1900.
^ Anstis 1997, p. 140.
^ Bessemer, Sir Henry (1905). An Autobiography. London: Engineering.
pp. 176, 180.
^ Blaenavon World Heritage Site: Blaenavon and the 'Gilchrist-Thomas'
Process Archived December 12, 2013, at the Wayback Machine.
^ Company, Lewis Publishing (1908-01-01). A century and a half of
Pittsburg and her people. Lewis Pub. Co. p. 41.
^ Chapter 18
Steel Making Archived 2011-01-22 at the
^ Rosenberg, Nathan (1982). Inside the Black Box: Technology and
Economics. Cambridge, New York: Cambridge University Press.
p. 90. ISBN 0-521-27367-6.
^ Misa, Thomas J. (1999) . A Nation of Steel: The Making of
Modern America, 1865–1925. Johns Hopkins studies in the history of
technology. Baltimore, Md.: The Johns Hopkins University Press.
ISBN 0-8018-6052-0. OCLC 540692649. Chapter 1 online.
^ Rosenberg, Nathan (1982). Inside the Black Box: Technology and
Economics. Cambridge, New York: Cambridge University Press.
pp. 60, 69. ISBN 0-521-27367-6.
^ Payne, P. L. (1968). "
Iron and steel manufactures". In Aldcroft,
Derek H. The development of British industry and foreign competition,
1875–1914; studies in industrial enterprise. London: George Allen
& Unwin. pp. 92–94, 97. OCLC 224674.
^ Abe, E. The Technological Strategy of a Leading
Bolckow Vaughan Co. Ltd: Late Victorian Industrialists Did Fail.
Business History, 1996, Vol. 38, No. 1, pages 45–76.
^ "Rail that Survived Demolition by "Lawrence of Arabia": An
Analysis". www.tms.org. Retrieved 23 February 2018.
^ Thomas J. Misa, A Nation of Steel: The Making of Modern America,
1865–1925 (1995): chapter on Holley and
Bessemer process online
^ Cheryl A. Kashuba, "William Walker led industry in the city", The
Times-Tribune, 11 July 2010, accessed 23 May 2016
Anstis, Ralph (1997), Man of Iron, Man of Steel: Lives of David and
Robert Mushet, Albion House, ISBN 0-9511371-4-X
Wikimedia Commons has media related to Bessemer converter.
"Progress in the Manufacture of Steel" in Popular Science
Monthly Volume 19, October 1881
"Bessemer's explanation of his process". The Engineer. 15 August
"How the Modern
Furnace Does Its Work". Popular Science:
30–31. February 1919.
Iron and steel production
History of ferrous metallurgy
List of steel producers
Bloomery (produces sponge iron)
Blast furnace (produces pig iron)
Direct reduced iron
Wrought iron (via
Finery forge or Reverberatory Puddling Furnace)
Cast iron (via
Cupola furnace or Induction furnace)
Pattern welding (Damascus steel)
Open hearth furnace
Electric arc furnace
Basic oxygen process
Vacuum arc remelting
Argon oxygen decarburization
Production by country