Bessemer process
Overview
 
The Bessemer process was the first inexpensive industrial process
Industrial process
Industrial processes are procedures involving chemical or mechanical steps to aid in the manufacture of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry....

 for the mass-production of steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 from molten pig iron
Pig iron
Pig iron is the intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux. Charcoal and anthracite have also been used as fuel...

. The process is named after its inventor, Henry Bessemer
Henry Bessemer
Sir Henry Bessemer was an English engineer, inventor, and businessman. Bessemer's name is chiefly known in connection with the Bessemer process for the manufacture of steel.-Anthony Bessemer:...

, who took out a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 on the process in 1855. The process was independently discovered in 1851 by William Kelly
William Kelly (inventor)
William Kelly , born in Pittsburgh, Pennsylvania, was an American inventor. Kelly studied metallurgy at the Western University of Pennsylvania. Instead of getting a job as a scientist, Kelly, his brother, and his brother-in-law started a dry goods and commission business, which they called...

. The process had also been used outside of Europe for hundreds of years, but not on an industrial scale. The key principle is removal of impurities
Steelmaking
Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required.-Older...

 from the iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 by oxidation with air being blown through the molten iron.
Encyclopedia
The Bessemer process was the first inexpensive industrial process
Industrial process
Industrial processes are procedures involving chemical or mechanical steps to aid in the manufacture of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry....

 for the mass-production of steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 from molten pig iron
Pig iron
Pig iron is the intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux. Charcoal and anthracite have also been used as fuel...

. The process is named after its inventor, Henry Bessemer
Henry Bessemer
Sir Henry Bessemer was an English engineer, inventor, and businessman. Bessemer's name is chiefly known in connection with the Bessemer process for the manufacture of steel.-Anthony Bessemer:...

, who took out a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 on the process in 1855. The process was independently discovered in 1851 by William Kelly
William Kelly (inventor)
William Kelly , born in Pittsburgh, Pennsylvania, was an American inventor. Kelly studied metallurgy at the Western University of Pennsylvania. Instead of getting a job as a scientist, Kelly, his brother, and his brother-in-law started a dry goods and commission business, which they called...

. The process had also been used outside of Europe for hundreds of years, but not on an industrial scale. The key principle is removal of impurities
Steelmaking
Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required.-Older...

 from the iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 by oxidation with air being blown through the molten iron. The oxidation also raises the temperature of the iron mass and keeps it molten.
The process using a basic refractory lining is known as the basic Bessemer process or Gilchrist-Thomas process after the discoverer Sidney Gilchrist Thomas
Sidney Gilchrist Thomas
Sidney Gilchrist Thomas was an English inventor.-Life:Thomas was born at Canonbury, London and was educated at Dulwich College....

.

Oxidation

The oxidation process removes and skims off impurities such as silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

,carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 as 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—the clay lining is used in the acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

 Bessemer
, in which there is low phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 in the raw material. Dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....

 is used when the phosphorus content is high in the alkaline
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

 Bessemer
(limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 or magnesite
Magnesite
Magnesite is magnesium carbonate, MgCO3. Iron substitutes for magnesium with a complete solution series with siderite, FeCO3. Calcium, manganese, cobalt, and nickel may also occur in small amounts...

 linings are also sometimes used instead of dolomite)—this is also known as a Gilchrist-Thomas converter, named after its inventor, Sidney Gilchrist Thomas
Sidney Gilchrist Thomas
Sidney Gilchrist Thomas was an English inventor.-Life:Thomas was born at Canonbury, London and was educated at Dulwich College....

. In order to give the steel the desired properties, other substances could be added to the molten steel when conversion was complete, such as spiegeleisen
Spiegeleisen
Spiegeleisen is a ferromanganese alloy containing approximately 15% manganese and small quantities of carbon and silicon. Historically, this was the standard form in which manganese was traded and used in steel making...

 (an iron-carbon-manganese alloy).

Managing the process

When the required steel had been formed, it was poured out into ladles and then transferred into moulds and the lighter slag is left behind. The conversion process called the "blow" was completed in around twenty 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 has greatly aided the blower in controlling the final quality of the product. After the blow, the liquid metal was recarburized to the desired point and other alloying materials are added, depending on the desired product.

Predecessor processes

Before the Bessemer process, Britain
United Kingdom of Great Britain and Ireland
The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom during the period when what is now the Republic of Ireland formed a part of it....

 had no practical method of reducing the carbon content
Decarburization
Decarburization is the process opposite to carburization, namely aimed at decreasing the content of carbon in metals . Decarburization occurs when Carbon in the metal reacts with gasses present in the atmosphere...

 of pig iron. Steel was manufactured by the reverse process of adding carbon to carbon-free wrought iron
Wrought iron
thumb|The [[Eiffel tower]] is constructed from [[puddle iron]], a form of wrought ironWrought iron is an iron alloy with a very low carbon...

, usually imported from Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. The manufacturing process, called cementation process
Cementation process
The cementation process is an obsolete technique 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...

, consisted of heating bars of wrought iron together with charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 for periods of up to a week in a long stone box. This produced blister steel. Up to 3 tons of expensive coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 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
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

. The most difficult and work-intensive part of the process, however, was the production of wrought iron done in finery forge
Finery forge
Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. To produce malleable wrought iron, it needs to undergo a further process. In the early modern period, this was carried out in a finery forge....

s in Sweden.

This process was refined in the 18th century with the introduction of Benjamin Huntsman
Benjamin Huntsman
Benjamin Huntsman was an English inventor and manufacturer of cast or crucible steel.-Biography:Huntsman was born the third son of a Quaker farmer in Epworth, Lincolnshire. His parents were Germans who had emigrated only a few years before his birth.Huntsman started business as a clock, lock and...

's crucible steel
Crucible steel
Crucible steel describes a number of different techniques for making steel in a crucible. Its manufacture is essentially a refining process which is dependent on preexisting furnace products...

-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 to about half an hour the time needed to make steel of this quality while requiring only the coke needed to melt the pig iron initially. The earliest Bessemer converters produced steel for £7 a long ton, although it initially sold for around £40 a ton.

History

Historian Robert Hartwell points out that the 11th century Chinese of the Song Dynasty
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...

 innovated a "partial decarbonization" method of repeated forging of cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 under a cold blast. The scholars Joseph Needham
Joseph Needham
Noel Joseph Terence Montgomery Needham, CH, FRS, FBA , also known as Li Yuese , was a British scientist, historian and sinologist known for his scientific research and writing on the history of Chinese science. He was elected a fellow of the Royal Society in 1941, and as a fellow of the British...

, Robert Temple
Robert K. G. Temple
Robert K. G. Temple is an American author best known for his controversial book, The Sirius Mystery which presents the idea that the Dogon people preserve the tradition of contact with intelligent extraterrestrial beings from the Sirius star-system...

 and Theodore A. Wertime acknowledged that this was the predecessor to the Bessemer process of making steel. This process was first described by the prolific scholar and polymath government official Shen Kuo
Shen Kuo
Shen Kuo or Shen Gua , style name Cunzhong and pseudonym Mengqi Weng , was a polymathic Chinese scientist and statesman of the Song Dynasty...

 (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
Henan
Henan , is a province of the People's Republic of China, located in the central part of the country. Its one-character abbreviation is "豫" , named after Yuzhou , a Han Dynasty state that included parts of Henan...

-Hebei
Hebei
' is a province of the People's Republic of China in the North China region. Its one-character abbreviation is "" , named after Ji Province, a Han Dynasty province that included what is now southern Hebei...

 border during the 11th century.

In 1740 Benjamin Huntsman
Benjamin Huntsman
Benjamin Huntsman was an English inventor and manufacturer of cast or crucible steel.-Biography:Huntsman was born the third son of a Quaker farmer in Epworth, Lincolnshire. His parents were Germans who had emigrated only a few years before his birth.Huntsman started business as a clock, lock and...

 developed the crucible technique for steel manufacture, at his workshop in the district of Handsworth
Handsworth, South Yorkshire
Handsworth is a suburb of south eastern Sheffield, in South Yorkshire, England. Handsworth has a population of approximately 15,000. It covers an overall area of approximately...

 in Sheffield
Sheffield
Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, and with some of its southern suburbs annexed from Derbyshire, the city has grown from its largely...

. This process had an enormous impact on the quantity and quality of steel production.

Sir Henry Bessemer described the origin of his invention in Chapters 10 and 11 of his autobiography
Autobiography
An autobiography is a book about the life of a person, written by that person.-Origin of the term:...

. According to this book at the time of the outbreak of the Crimean War
Crimean War
The Crimean War was a conflict fought between the Russian Empire and an alliance of the French Empire, the British Empire, the Ottoman Empire, and the Kingdom of Sardinia. The war was part of a long-running contest between the major European powers for influence over territories of the declining...

 many English industrialists and inventors became interested in military technology and Bessemer himself developed a method for grooving artillery projectiles so that they could spin without the use of rifling
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

 in the bore of the gun. He patented this method in 1854 and began developing it in conjunction with the government of France. After a successful day of testing of his method at the Polygon in France he had a conversation with Claude-Étienne Minié who stated that a key barrier to the use of the larger, heavier spinning projectiles would be the strength of the gun and in particular "...he [Minié] did not consider it safe in practice to fire a 30-lb. shot from a 12-pounder cast-iron gun. The real question, he said, was; Could any guns be made to stand such heavy projectiles?". This is what started Bessemer thinking about steel. At the time steel was difficult and expensive to make and was consequently used in only small items like cutlery and tools. Starting in January 1855 he began working on a way to produce steel in the massive quantities required for artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 and by October he filed his first patent related to the Bessemer process.

According to his autobiography Bessemer was working with an ordinary reverbatory 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, 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
William Clay
William Clay may refer to:*William Clay, owner of the Mersey Steel and Iron Co, an early user of Bessemer process in Liverpool *Bill Clay , politician from the state of Missouri*William Lacy Clay, Jr...

—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 such 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
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 which was part of the air blast passing through the steel.

The solution was first discovered by English metallurgist Robert Forester Mushet
Robert Forester Mushet
Robert Forester Mushet was a British metallurgist and businessman, born April 8, 1811, in Coleford, in the Forest of Dean, Gloucestershire, England. He was the youngest son of Scottish parents, Agnes Wilson and David Mushet; an ironmaster, formerly of the Clyde, Alfreton and Whitecliff...

, who had carried out thousands of experiments in the Forest of Dean
Forest of Dean
The Forest of Dean is a geographical, historical and cultural region in the western part of the county of Gloucestershire, England. The forest is a roughly triangular plateau bounded by the River Wye to the west and north, the River Severn to the south, and the City of Gloucester to the east.The...

. 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
Spiegeleisen
Spiegeleisen is a ferromanganese alloy containing approximately 15% manganese and small quantities of carbon and silicon. Historically, this was the standard form in which manganese was traded and used in steel making...

. 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 uses.

The first company to license the process was the Manchester firm of W & J Galloway
W & J Galloway & Sons
W & J Galloway and Sons was a British manufacturer of steam engines and boilers, based in Manchester, England. The firm was established in 1835 as a partnership of two brothers, William and John Galloway. The partnership expanded to encompass their sons and in 1889 it was restructured as a limited...

, 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
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. This was the first commercial production.

Patent battles

Patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

s of such value did not escape criticism, and invalidity was urged against them on various grounds. But Bessemer was able to maintain them intact without litigation, though he found it advisable to buy up the rights of one patentee, and in the case of Mushet 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, a very considerable sum, which he paid for 25 years.

In 1866, Bessemer also provided finance for Zerah Colburn
Zerah Colburn (locomotive designer)
Zerah Colburn was an American engineer specialising in steam locomotive design, technical journalist and publisher.- Career :Without any formal schooling, Colburn was a teenage prodigy...

, 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. Prior to the launch of Engineering, Colburn, through the pages of The Engineer, had given support to Bessemer's work on steel and steelmaking
Steelmaking
Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required.-Older...

.

Importance

The Bessemer process revolutionized steel manufacture by decreasing its cost, from £40 per long ton to £6–7 per long ton during its introduction, 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. Prior to its introduction, steel was far too expensive to make bridges or the framework for buildings and thus wrought iron had been used throughout the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

. After the introduction of the Bessemer process, steel and wrought iron became similarly priced, and most manufacturers turned to steel. Some claim the availability of cheap steel allowed large bridges to be built and enabled the construction of railroads, skyscrapers, and large ships; however, the largest ship of the 19th century was the iron SS Great Eastern
SS Great Eastern
SS Great Eastern was an iron sailing steam ship designed by Isambard Kingdom Brunel, and built by J. Scott Russell & Co. at Millwall on the River Thames, London. She was by far the largest ship ever built at the time of her 1858 launch, and had the capacity to carry 4,000 passengers around the...

 launched in 1858, high pressure steam-powered locomotive railways appeared in 1825 with the opening of the Stockton and Darlington railway
Stockton and Darlington Railway
The Stockton and Darlington Railway , which opened in 1825, was the world's first publicly subscribed passenger railway. It was 26 miles long, and was built in north-eastern England between Witton Park and Stockton-on-Tees via Darlington, and connected to several collieries near Shildon...

 (the first passenger railway opened in 1830 between Liverpool and Manchester
Liverpool and Manchester Railway
The Liverpool and Manchester Railway was the world's first inter-city passenger railway in which all the trains were timetabled and were hauled for most of the distance solely by steam locomotives. The line opened on 15 September 1830 and ran between the cities of Liverpool and Manchester in North...

), and the first modern large suspension bridge was the Menai Suspension Bridge
Menai Suspension Bridge
The Menai Suspension Bridge is a suspension bridge between the island of Anglesey and the mainland of Wales. Designed by Thomas Telford and completed in 1826, it was the first modern suspension bridge in the world.-Construction:...

 completed in 1826: the latter both decades before mass produced steel. Other important steel products—also made using the open hearth process—were steel cable, steel rod and sheet steel which enabled large, high-pressure boilers and high-tensile strength steel for machinery which enabled much more powerful engines, gears and axles than were possible previously. With large amounts of steel it became possible to build much more powerful guns and carriages, tanks, armored fighting vehicles and naval ships. Industrial steel also made possible the building of giant turbines and generators thus making the harnessing of water and steam power possible. The introduction of the large scale steel production process paved the way to mass industrialisation as observed in the 19th–20th centuries.

However, 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 predominated. The 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 any intrinsic to the process itself.

Obsolescence

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
Basic oxygen steelmaking
Basic oxygen steelmaking , also known as Linz-Donawitz-Verfahren steelmaking or the oxygen converter process is a method of primary steelmaking in which carbon-rich molten pig iron is made into steel. Blowing oxygen through molten pig iron lowers the carbon content of the alloy and changes it into...

, which offered better control of final chemistry. The 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
Scrap
Scrap is a term used to describe recyclable and other materials left over from every manner of product consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap has significant monetary value...

 steel to be charged, further increasing costs, especially when scrap was inexpensive. Use of electric arc furnace
Electric arc furnace
An electric arc furnace is a furnace that heats charged material by means of an electric arc.Arc furnaces range in size from small units of approximately one ton capacity up to about 400 ton units used for secondary steelmaking...

technology competed favourably with the Bessemer process resulting in its obsolescence.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK