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Iron and steel smelting, industry and company histories
This section provides background information to the section on adding an iron works, steel works or metals stockholders to a model railway layout. Mining iron ore is discussed separately in 'Lineside Industries - Mining metal ores and smelting non ferrous metals'
General History of the Iron and Steel making process
Iron is probably the most important metal known to man, without it life as we know it today could not exist. Although other metals are used in considerable quantity, notably aluminium, copper, tin, lead and zinc, iron is still the most important. Iron possesses magnetic properties which allowed the development of electrical power.
By the early sixteenth century the area in the South of England known as the Weald was the main centre of production using the charcoal method but there were groups of charcoal fired blast furnaces in the Forest of Dean, South and North Wales, the West Midlands, Derbyshire, Yorkshire, Furness and the North Staffordshire-Cheshire border.
Both iron and steel are the same material but in the latter more of the impurities (mainly carbon) are removed. The British Industrial Revolution, the first in the world, was based on iron, the rest of the world industrialised later and based their machines on steel.
Recovering metals from ore is called smelting, this is usually done by heating the ore to the melting point of the metal in a blast furnace. This drives off some of the impurities and others burn in the furnace to form gasses, meanwhile the required metal melts and this can be separated from other molten materials (slag) by settling them out.
The blast furnace consists of a large oven built to withstand high temperatures and supplied with air under pressure, the ore and fuel are placed inside and set alight, melting the metal ores and separating them from the rock they were found in. The blast furnace was introduced into Britain in the fifteenth century and up to the early eighteenth century these were fuelled with charcoal. The iron these furnaces produced was good enough to build the first steam engines in about 1712.
Iron was discovered thousands of years ago but early extraction methods relied on charcoal made from wood which was time consuming, expensive and only available in small quantities. Up to 1709 charcoal was used as a fuel for the blast furnaces which separate the iron from the oxygen and other impurities.
Abraham Darby then developed the use of coke in place of charcoal, he did not protect the process with patents and this allowed the rapid development of the iron industry. In Darby's time British iron production was running at 17,000 tons a year, by the 1950's it was up to over fifteen million tons a year. The 'pig iron' produced in the blast furnace has a high carbon content and cannot practically be used for very much. if however it is re-melted more impurities can be removed. This re-melting is usually done in a small scale blast furnace called a 'cupola furnace' (invented in the 1790's by a British ironmaster called John Wilkinson). Scrap metal can be recycled in this furnace along with the pig iron. The molten iron which comes out of a cupola furnace flows well and can be used to make solid castings, it is called 'cast iron'. Cast iron contains a lot of carbon and tends to be brittle, it serves well under compression but is poor when placed under tension. Places which take in pig iron to make cast iron are called 'foundries', you would normally have a foundry associated with an iron works but there were also small establishments catering to local industry (most towns had at least two small foundries) and larger engineering works often had their own foundry on-site.
Pig iron can be used to make cast iron goods in a foundry (see also Lineside Industries - Scrap metal yards, Foundries and Forges) but this material, although resistant to rusting and strong under compression, is brittle and cannot be re-heated and shaped. Cast iron is still widely used today (motor car engine blocks are made of cast iron).
If you remove nearly all the carbon from pig iron or cast iron you get 'wrought iron' (sometimes called 'malleable iron' in older texts) which contains less than 0.1% carbon and about 3% 'slag'. The original method for making this was to bake it at red heat for about a week (this approach remained in use into the early 20th century). Better wrought iron was made by beating bars of red hot cast iron and beating it to de-form it and allow the air to get at more of the carbon (which then burns away). This was done in a works known as a 'finery'.
In 1784 an iron works owner by the name of Henry Cort obtained a patent for producing wrought iron in bulk by stirring molten iron in a reverbatory furnace (a process known as 'puddling', for a description of a reverbatory furnace see Lineside Industries - Prototype industrial ancillary structures). What happens is that the air would oxidise and remove some of the remaining carbon (becoming CO2 gas) producing low carbon wrought iron. Mr Cort also developed and patented a hot rolling process for iron heated until it was the consistency of a thick paste and then passed between powered rollers in a rolling mill which produced better quality iron much faster. The combination of these two developments allowed his works to produce about fifteen times as much iron in a given time and with a given amount of fuel. Cort's business partner was then prosecuted for fraud and (as he was a full partner) Cort was also held responsible and his patents (both for the puddling furnace and his wrought iron rolling mills) were confiscated and thrown open to all manufacturers, the result was a massive increase in wrought iron production. The combination of cast and wrought iron along with Mr Cort's rolling mill allowed the industrial revolution to mechanise production but by the 1870's iron production had peaked and the industry went into slow decline as steel began to become the more significant material.
Cort's puddling process was further improved in 1816 when Joseph Hall of Tipton developed an oxygen rich lining for the puddling furnace (this was called 'wet puddling' to differentiate it from Cort's system which in turn became known as 'dry puddling'). A small quantity of haematite ore is added to the pigs of iron in the cupola at the foundry. The oxygen in the haematite (Fe3O2) combines with most of the carbon in the pig iron to form carbon dioxide and the resulting iron has less than 0.1% carbon in it.
Wrought iron is much stronger under tension than cast iron and the slag forms a coating or skin on the surface which imparts certain qualities to the metal, notably corrosion resistance. Wrought iron can also be heated and rolled into long strips or sheets. The first sheet rolling mill was built in Wales in about 1720 but machines for cutting hand made sheets into strips had been in use since the sixteenth century. Henry Cort's iron rolling mills, using grooved rollers which produced bars of standard thickness, represented a major advance.
Wrought iron can also be formed to shape by beating it and belting it with a hammer or pressing it over a former. This heating and forming with hammers and presses is called forging (a forge is a hammer and an anvil). A forge consists of a solid base and a hammer, a blacksmith's forge had the anvil and the blacksmith used a hand held hammer. The early 'industrial' forges used water-power to drive the hammer, steam powered hammers were invented in Britain in 1839 by James Naysmith (1808-1890) and further developed in France in 1842. Wrought iron was formed in the forge to make bridge parts, sections for ship building and railway lines. In 1861 the British developed the hydraulic press which was strong enough to force iron sheets to shape.
The most common iron ore in Britain is Spathic ore mixed with clay, called 'ironstone'. To recover the iron the ironstone is first roasted by mixing it with a little coal or coke and burning it in small heaps or shallow kilns (this is sometimes done at the mine site as illustrated in Fig ___). This drives off the water, sulphur, arsenic and some carbon dioxide. The resulting partly purified ore is then put in a blast furnace with coke and limestone and set alight. Pre-heated air is blown in through the bottom (the inlet pipes for this air are called tuyeres).
The coke burns to form carbon dioxide gas and heats the mix up to about fifteen hundred degrees centigrade. The limestone and ore melt and the super hot carbon dioxide de-composes the limestone (calcium carbonate), the calcium combines with the residual sand in the now molten ore to form calcium silicate. The molten iron sinks to the bottom and the semi-molten calcium silicate floats on top as a 'slag'. The slag is tapped of and sold for road making and for use as an agricultural soil conditioner for acidic soils (it was ground to a powder and sold as 'basic slag').
The iron and slag are tapped off at intervals of a few hours, fresh materials being poured in at the top and the blast furnace is kept going twenty four hours a day for years, until the brick lining requires replacement. The operation of the blast furnaces produces a lot of soot and smoke, the south of Staffordshire became known as 'the Black Country' (red by night, black by day) following the development of the iron works there in the eighteenth century.
The molten iron tapped from the blast furnace can be flowed into sand moulds where it forms blocks called 'pigs' (said to be named after the similarity of the row of moulds to a row of piglets feeding on mum). More recently a chain of metal moulds has been used, carrying the iron under a water spray to cool it and tipping out the 'pigs' at one end. In many works the liquid iron is moved for further processing in crucible wagons similar to the slag wagon shown above.
Steel Works
Steel works are similar to iron works but with an additional stage of processing as shown on the flow diagram below. Any steel works will therefore include a blast furnace, its design depending on the date of your layout.
Fig ___ Iron & Steel Making Flow Diagram
Steel is iron with all the carbon removed and a little added back in, this produces something chemically similar to wrought iron but with a different crystalline structure. Up to the middle of the nineteenth century it was made in small pots (called 'crucible steel') and prices reflected the small scale and labour intensive manufacture. By the 1850's Britain was producing several million tons of iron in various forms every year but only a little steel. Things changed in the mid 1850's when Henry Bessemer invented his 'converter' in which air is blown through molten iron, the oxygen in the air burns away the carbon to produce very pure wrought iron. To clear away the oxygen dissolved in the molten metal and restore the required amount of carbon to make steel a little ferro-manganese (an alloy of iron, manganese and carbon) is then added. The manganese combines with any free oxygen whilst the carbon combines with the iron to make steel. The steel is teemed (poured into moulds) to form ingots which are then re-heated to enable them to be rolled or hammered into shape.
Bessemer's converter was a major breakthrough but it could only be used with very pure ores, most of which had to be imported from Spain and Sweden. Much of the iron ore in Britain (and in the rest of the world) is tainted with phosphorous and although it made good iron it could not be used for making steel. In 1876 Sidney Gilchrist Thomas working with his cousin discovered that he could line the Bessemer vessel or open hearth with crushed dolomite (MgOCaO), which reacts with and removes the phosphouous, producing a phosphate slag which had the additional benefit of being a valuable fertiliser ('Basic Slag').
The next big development was the Siemens-Martin or open hearth process of 1866, using the reverbatory regenerative furnace invented by Frederick Siemens (1826-1904) in 1856. The regenerative furnace uses the waste heat generated to pre-heat incoming air instead of simply blowing it out of the top as in the Bessemer system. The re-use of the heat allows pigs of cold iron to be used to charge the furnace instead of the molten iron of the Bessemer system. To make 100 tons of steel in the open hearth system requires up to fifteen hours of careful work as opposed to about twenty minutes in the Bessemer converter. The open hearth process requires a lot more skill on the part of the operators, but it is a lot cheaper due to the re-use of the heat. The Bessemer system remained in use up to about 1925, rapidly decreasing in use after the First World War, and thereafter the Siemens open hearth method became the standard method for steel production world wide until the late 1950's.
In 1863 Henry Clifton Sorby (1826-1908) working in Sheffield discovered the microstructure of steel and founded modern metallurgical science. Steel gradually replaced wrought iron for most applications although wrought iron production peaked long after the development of steel and remained significant up to the 1930's. There was a puddling furnace producing wrought iron at the Butterly Ironworks which remained in use until 1965 (no better way of making wrought iron having been found). Cast iron's particular properties mean that it remains in use today.
Adding a 'basic' lining to Bessemer furnaces allowed them to process steels with a high phosphorous content (that is most British ores other than Haematite), adding this lining to a Siemens-Martin furnace provided similar benefits. Imports of ore had reached over 2.5 million tons per year by 1880, having risen steeply since 1870, with the vast majority coming from Spain. Steel production in Middlesborough was dependent on imported ore, nearly 1.3 million tons in 1895. By 1950 British mined ores were dominated by the Jurassic Scarp in the Midland counties but we had used up virtually all of the Hematite (a small number of mines continued to operate into the latter part of the 20th century, but they were no longer important for British steel production as it moved to the use of electric refining furnaces).
The Basic Oxygen Process for making steel was developed in Austria in about 1950, and this system has turn largely replaced the open hearth system. The Basic Oxygen Process uses pure oxygen in large quantities (called 'tonnage oxygen') which is blown into the liquid metal to combine with the carbon and remove it (lime can also be injected to reduce the phosphorous content). The oxygen used for this system is usually made on site but when the on-site equipment is being serviced oxygen is delivered in British Oxygen Company liveried cryogenic (low temperature) railway tank wagons.
There is one other option for making steel, the electric furnace process, which offers the possibility of turning the heat up or down and thus controlling directly the creation of the steel. It costs a lot to make steel in this way so the technique is only used for making high grade alloy steels such as stainless steels and steel used for cutting tools.
By 1968 technology had improved to the point where molten steel could be poured into the top of a water cooled mould and drawn out as a continuous bar at the bottom. This technology was soon adopted in most of the worlds major steel works.
There are many kinds of steel, the two main categories are carbon steel and alloy steel. The carbon steels are the most widely used and the characteristics vary depending upon the amount of carbon they contain. Low (less than 0.7% carbon), Mild (0.1 to 0.25% carbon), Medium (0.2 to 0.5% carbon and high (0.5 to 1.4% carbon) Low carbon steels are called soft and these are used for wire sheet metal and rivets, high carbon steels are called hard and they are used for springs, hammers and chisels.
Alloy steels are used for specialised applications, stainless steel contains about 14% chromium and usually has some nickel in it as well, it was discovered by Harry Braille of Sheffield in 1913. The firm he was working for was trying a range of alloys and after testing the ingots were piled up as scrap. He noticed that some of the ingots they had experimented on did not rust but remained shiny. Manganese steel is used for the teeth of excavators and other tough jobs, made from iron ore which contains the material.
British Iron & Steel Industry
Although at the forefront of the early European iron industry Britain soon began to fall behind. By the 1890's American iron production was greater than Britain's, in 1904 Germany pulled ahead and the General Strike of 1926 pushed Britain into fourth place behind France. The main reason British iron and steel industry fell behind the international competition was that it remained a fragmented collection of relatively small scale businesses. The USA, France and Germany were all embarking on their own industrial revolutions, their iron and steel firms were soon in fierce international competition which they fought by forming conglomerates and cartels. The Americans such as Andrew Carnegie (United States Steel Corporation) and the German industrial cartels had the advantages of the economies of scale and were better able to weather the dips in demand than the smaller British firms. Between 1870 and 1913 British coal production fell by about fifty tons per man per year and prices rose, this was the reverse of the situation in America and adversely affected the British iron industries competitiveness.
It is in the nature of the business that when times are good everyone wants steel, but even a slight fall in industrial growth has a disproportionately damaging effect on the iron and steel industry. Foreign producers were protected by tariff systems whereas the British were not, this meant that during lean times there was considerable 'dumping' of foreign steel in Britain.
By the time the of the First World War the industry was not healthy and was ill prepared to meet the sudden increase in demand. Many of the smaller firms had to amalgamate to allow for investment in new plant but when the war ended the industry found itself with a considerable over capacity and with much of its manufacturing facilities poorly located. There was a brief post war boom but the slump in demand hit in the 1920's and lasted a decade. Many of the several hundred smaller firms failed and were taken over by banks. Unemployment amongst steel workers seldom dropped below thirty percent during this period.
There was considerable pressure to nationalise the industry, starting in the early 1930's but things picked up again in the later part of that decade. In 1932 the government set up an organisation to support the industry (which was represented by the British Iron and Steel Federation or BISF until 1967 when the BISF was dissolved and its affairs were then wound up by a committee appointed by the British Steel Corporation and the British Independent Steel Producers Association) and in 1937 an organisation called BISC (the British Iron & Steel Control (Ore) Ltd.) was formed to distribute home produced ores (mainly from the Lincolnshire ore fields). This organisation was established by the BISF to be responsible for all imports of iron ore and manganese ore required by the industry. BISC also arranged centrally the shipping needed for the industry's ore imports, drawing on a fleet of seventy specially designed ore carriers operating on long-term charters. The company was a wholly-owned subsidiary of the British Iron and Steel Corporation Limited, which in turn became a wholly-owned subsidiary of the British Steel Corporation in 1967. From the 1930s to the later 1960s (possibly later) BISC operated a number of ore hopper wagons in its own livery. Several model hoppers have been offered in various scales, but all have been based on existing models and I am unsure if any are accurate.
The Second World War saw a different pattern of development from the First, for one thing a degree of rationalisation had already occurred within the industry and the industry's own co-ordinating body (BISF) was able to change to a war footing. In this war the industry concentrated on building specialist mills for processing steel imported as billets from America, which meant the post war problems of poor location and over capacity were largely avoided.
Nationalisation came with the post war labour government in 1948, however the Conservatives de-nationalised the industry in the early to mid 1950s, following their victory in the 1951 election. At this time there were a small number of large steel firms still trading, some operating several steel works but quite a few smaller works were still operating into the 1970s. At the end of this section I have appended details of the major steel companies operating in the UK
Neither the wartime nationalisation nor the post war privatisation resolved the continuing problems in the industry and after much debate a revised form of nationalisation of a large part of the industry (including the fourteen largest plants in the country) occurred in 1967 with the formation of the British Steel Corporation. By 1973 the British Steel Corporation was again making a profit.
Fig ___ British Steel logo
British ore suffers from high levels of impurities, it has only a small amount of iron in it and consequently requires more coke for processing. Imported ore although more expensive has a greater yield of iron and uses less coke so it is less dependant on the cost of coal. As a result, particularly since the 1950's, there has been a shift of major manufacturing away from domestic sources of coal and ore (mainly in the Midlands) toward coastal sites.
British Steel concentrated production in four areas, Glasgow (Ravenscraig), Middlesborough on the North East Coast, Sheffield and Scunthorpe in the North East Midlands and Port Talbot & Llanwern in South Wales. The facilities at Ravenscraig and Llanwern were developed from existing privately owned works in the late 1950's and largely duplicated each other. Ravenscraig was partly funded by the government who wanted it to supply steel to the then booming ship building industries of the Clyde and Northern Ireland. The plant was operated by a company called Colvilles, who were very dubious about the plants viability in the long term. These worries proved well founded and the plant was finally closed down in 1992.
Not all firms were taken into British Steel, smaller firms continued to operate on most of the coalfields such as those around Liverpool and Manchester (Lancashire Steel Corporation), and the belt between Wolverhampton and Kettering. The steel making industry at Barrow was supported by its shipbuilding industry (although by the 1960's it was loosing money) and Workington in the far North West also had a steel industry, built on the local haematite ore but lather using imported ores I believe. Most of the smaller firms fell by the wayside in the face of the glut of steel on the worlds markets, the massive steel plant at Consett closed in 1980 and the big Stewarts & Lloyds steel works at Corby (set up in the early 1930s) closed down in the early 1980's.
The map below, based on information supplied by the British Steel Corporation, shows the main steel works operating in Britain in about 1980.
Fig ___ Iron And Steel Works In Britain (as at about 1980)
Over the years Sheffield had developed a specialised industry producing unusual high quality steels and alloys. The barrel of the British 105mm L1A1 tank gun (the most widely used tank armament in the West) was made from 'electro-slag refined' steel produced using a process developed in Sheffield in the 1950's. Although the scale of the industry in Sheffield in today (later 1980s) much reduced it remains the centre for British high technology steel making.
British Steel was privatised in 1988 to become British Steel Plc and merged with Dutch firm Koninklijke Hoogovens to form Corus in 2000. On April 2 2007, Corus became a subsidiary of the Indian owned Tata Steel. The company still trades as Corus and operates several steel plants in the UK.
Some British steel manufacturers
Steel Co. of Wales
Steel Co. of Wales was formed in 1947 and grew to become the largest steel company in Europe (producing upwards of three million tons of steel a year by the later 1960s). In the post-ear privatisation of the 1950s they set up two completely new tinplate works at Swansea and Llanelli. This company incorporated the Dowlais Iron Company (est 1759), Blaenavon Co Ltd (set up in 1836, this name adopted in 1879), Margam Steelworks at Port Talbot (1921), Ebbw Vale (set up in 1789, the name became Ebbw Vale in the 1860s although it was subsequently owned by Baldwins and from 1954 by the merged Richard Thomas & Company Ltd and Baldwins Ltd. This works closed in stages from the later 1990s until 2002).
United Steel Companies Ltd. Certainly operating by the 1920s and based in Sheffield, this firm owned many collieries.
Stewarts & Lloyds Based at Corby Northants. Their giant integrated steel works was built in the early 1930s, replacing an earlier iron works dating back to the turn of the century. Production at the new plant began in 1935.
John Summers Operated Shotton Steelworks in Flintshire (North East Wales, on the River Dee not far from Chester).
Dorman Long Registered in 1889 Operated a large plant at Port Clarence near Middlesborough. Also owned Carlton Iron Co. Ltd.
Colvilles The most famous of the Scottish firms, handled most steel works north of the Scottish border. Colvilles was a core Scottish firm, established in 1871 as the 'Dalzell Steel and Iron Works'. They subsequently purchased Fullwood Foundry Company (Ingot Moulds and similar castings. At the request of the Government they re-started Clydebridge Steel Works in 1915. About the same time the Company took lease of the Steel Works at Glengarnock.
Consett This works was located about 10 miles south west of Newcastle upon Tyne, the Consett Iron Company was established in 1840 by a small group of entrepreneurs who introduced the first blast furnaces. Over the next 100 years, the town became one of the world's leading steel making towns. This works closed in 1980 although the nearby Teeside Steel works at Redcar continued in production.
Lanes Steel Co.
Ran the Barrow Hematite Steel Co., Ltd., Barrow-in-Furness.
Hadfields Based in Sheffield
South Durham Steel
Firth & Brown
Firth & Brown The Firth Brown company was formed in 1930 after the amalgamation of Thomas Firth & Sons and John Brown & Co. Both companies had established reputations, together they became one of Sheffield's largest employers. Stainless steel was developed in the Brown-Firth research laboratories in 1913. This lead to the great alloy steel industry which still makes Sheffield a high quality steel producing city today. With associated companies in Scunthorpe, Darnall and Clydebank, Firth Brown produced high quality steel castings and forgings for various industries in this country and around the world.
One company remained as a nationalised operation into the 1950s, this was Richard Thomas & Baldwins Which I believe was then bought by Whiteheads.
Shelton Iron Steel and Coal Co
Situated between Etruria and Hanley in the Potteries. 1841 'Shelton Coal & Iron Works' was converted into wrought (malleable) iron in the puddling furnaces of an adjacent, but nominally separate business, the Shelton Bar Iron Company. In 1889 Earl Granville's iron and coal business finally amalgamated with the Shelton Bar Iron Co. the new company was named Shelton, Iron, Steel & Coal Co. Ltd. In 1920 the Shelton complex acquired by John Summers & Sons Ltd, to provide them with raw materials (pig iron, coal and coke) for their Shotton ironworks on Deeside. Under Summers ownership Shelton was transformed into an extremely efficient, modern plant. Continuous casting using new plant started in 1964, last steel produced 1978, plant closed 2000.
Blaenavon Iron and Coal Company
This company was set up in 1836 when they purchased the ironworks at Blaenavon, Monmouthshire. They repeatedly ran into financial difficulties and were repeatedly reestablished, first as the Blaenavon Company Ltd, in 1870 it became the Blaenavon Iron and Steel Company Ltd but the change to steel production brought more problems and the company was reestablished as Blaenavon Co. Ltd (the 'New Company'), incorporated in 1879. The works were extended by the erection of a Coke Oven and By-Product Plant in 1911 and a steel solid wheel and axle plant between 1937 and 1941.
Guest, Keen & Nettlefolds, Ltd. or GKN
Initially based at Dowlais, their steel making was merged with Baldwins, Ltd. in 1930 to form Guest, Keen, Baldwins Iron and Steel Co., Ltd. They were nationalised in the immediate post war era, when de-nationalised in the 1947 they became Steel Company of Wales (discussed above).
