Bessemer process – The Melting Pot

Memories of Old Merthyr

We continue our serialisation of the memories of Merthyr in the 1830’s by an un-named correspondent to the Merthyr Express, courtesy of Michael Donovan.

It was at the Dowlais Works the Bessemer process for the conversion of pig into malleable iron was tried, with the result, as told me by Sir Henry himself, “I was knocked down on my back, and for two years could not get up again”. The Bessemer process, as everyone knows, is to blow air through the molten metal and so burn the carbon out, but many years before that blowing steam through molten iron in the puddling was tried there. The furnace with the apparatus was seen in the upper forge – that is, between the Dowlais office and the fitting shop.

Sir John himself conceived the idea of running the iron direct from the blast furnace into the refinery, so as to avoid the remelting usually followed. It was used for a while at the Ivor Works at the furnace next to the engine-house on the Pant side, but the refinery process itself was soon superseded to a great extent.

The Bessemer Converter at Dowlais Ironworks in 1896. Photo courtesy of the Alan George Archive

It was at Dowlais the very first steam whistle was made, and although the tale has been previously told, the use of the whistle for railway purposes is so extensive that it will be again told in the words of the inventor himself as told to me personally by him.

For the better understanding of it allow my saying that a column of water about 27 inches high gives a pressure of a pound for every square inch of its area, and for the feeding of his boilers James Watt had designed an automatic arrangement, based upon the weight above mentioned. Even up to 10lbs, a standpipe 270m inches high would suffice, but when it comes to 50lbs the pipe would be excessive, and as some little looking after is needed, it would be rather inconvenient, so that the regulation of the feed became dependent on the care of the stoker, he being guided by the use of gauge cocks. Stokers are human, and therefore remiss; the feed goes too low, overheating of the plates follows. This reduces their strength, perhaps, too, the steam pressure increases, and disaster follows.

Adrian Stephens inventor of the first steam whistle

Something of this kind happened, and Sir John asked Adrian Stephens if it were possible to arrange something to indicate that the feed was getting low. The upshot of the conversation was that one of the pipes from the organ in the house was sent for Stephens’ consideration. In Watts’ arrangement a float was used for governing the feed, and Stephens very naturally followed the idea. The idea of an inside valve was evolved, and by the passing of steam through the organ pipe sound was produced. It then occurred to Stephens that if the emission aperture were made all around the pipe it would be better, and he made it so.

It did not bring him profit, nor was he ever honoured as he should have been. Some Manchester workmen were then down with tools for the fitting-shop, and they either communicated or took the idea back there, and not as a regulator for feed, but as a means of calling attention the whistle became used in locomotion.

To be continued at a later date…..

Merthyr’s Ironmasters: G T Clark – part 1

This article is a transcription from a publication now in the public domain: Dictionary of National Biography (1st supplement). London: Smith, Elder & Co. 1901

George Thomas was born in London on 26 May 1809, the eldest son of George Clark (1777–1848), chaplain to the royal military asylum, Chelsea, and Clara, only surviving daughter of Thomas Dicey of Claybrook Hall, Leicestershire, and he was educated at the Charterhouse. Adopting engineering as a profession, he was entrusted by Brunel with the construction of two divisions of the Great Western Railway; the Paddington terminus and the bridges at Basildon and Moulsford being his principal works While thus engaged he compiled ‘A Guide-book to the Great Western Railway, containing some Account of the Construction of the Line, with Notices of the Objects best worth Attention upon its Course’ (London, 1839). This, the first guide to the line, was published officially without his name, and dedicated to Brunel. A more detailed account, which he subsequently wrote, of the geology and archæology of the country traversed by the railway, was published, with numerous illustrations, as ‘The History and Description of the Great Western Railway’ (London, 1846); but the only name attached to it was that of the artist, John C. Bourne.

In about 1843 Clark went to India, where he was employed by the government to report on the sewerage of the native town at Bombay, and afterwards upon the extension of the salt works of the district. Here he advocated the construction of the first railway in India, that from Bombay to Tannah, afterwards merged in the Great Indian Peninsula Railway, for the promoters of which he also reported on the feasibility of an extension through one of the mountain passes of the Sahyadri or Western Ghauts. On account of the climate he declined an offer of the chief engineership of the new line and returned to England. In consequence of an article on sanitary reform which he contributed to the ‘Westminster Review,’ he was appointed a superintending inspector under the Public Health Act, 1848, and reported on the sanitary condition of a large number of towns and districts, in many of which local boards were formed through his efforts. His success as an inspector was recognised by his promotion to be one of the three commissioners which then constituted the general board of health.

Towards the close of 1852 Clark, however, became trustee of the Dowlais Estate and Ironworks, under the will of Sir Josiah John Guest. For some time previously the works had been carried on at a loss; but having procured the necessary capital and induced Henry Austin Bruce (afterwards Lord Aberdare) to share with him the responsibility of the trusteeship, Clark took up his residence at Dowlais and devoted all his energies to the development of the works and the redemption of the estate. As Bruce devoted himself to politics, the whole responsibility of management devolved on Clark alone, whose rare capacity for administration was displayed no less by his rapid mastery of a complicated situation than by his wise selection of heads of departments, chief among whom was his manager, William Menelaus.

© William Menelaus (1818-1882); Hagarty, Parker; Cardiff University; http://www.artuk.org/artworks/william-menelaus-18181882-159291

To Clark and Menelaus belongs the credit of being the first ironmasters to assist (Sir) Henry Bessemer to perfect his process for making malleable iron direct from the ore. The inventor was invited to Dowlais to conduct experiments, with the result that the first rail ever rolled without the intervention of the puddling process was produced at Dowlais. The prompt adoption of Mushet’s further invention enabled Dowlais to be first in the field in the production of steel rails, and to enjoy for some time the monopoly of that trade in Wales. The consequent expansion of the industry, and the difficulty of procuring an adequate supply of suitable ores at home, led Clark, in conjunction with the Consett Iron Company and Messrs. Krupp of Essen, to acquire an extensive tract of iron-ore deposits near Bilbao in Spain.

To render the works independent of the vicissitudes of the coal trade he also purchased large coal areas, undeveloped for the most part, in Glamorganshire. To save the inland transport he finally procured the establishment, in 1888-91, of furnaces and mills in connection with Dowlais, on the seaboard at Cardiff. He was induced by Lord Wimborne (Ivor Guest, eldest son of Josiah John) to continue his administration of the Dowlais undertakings down to the end of March 1897, though his trusteeship had expired more than twenty years previously. Under his regime Dowlais became in effect a great training school which supplied to similar undertakings elsewhere a much larger number of managers and leading men than any other iron or steel works in the country.

To be continued…….

Terrible Accident in Dowlais

As reported in the Western Mail 120 years ago today (14 February 1899):

TERRIBLE ACCIDENT AT DOWLAIS

FALL OF A ROOF AT THE IRON COMPANY’S WORKS

ONE MAN KILLED AND SEVERAL INJURED

THOUSANDS OF POUNDS DAMAGES

(From our Dowlais correspondent – Dowlais, Wednesday Night)

Great excitement prevailed at Dowlais this evening consequent upon a terrible accident which occurred in the Lower Works. First reports stated that the machinery in the Bessemer department, bad been blown to pieces by an explosion and that about a dozen persons had been killed. For more than two hours the town was in a terrible state of agitation, and crowds of people flocked to the gates of the Lower Works. Such a state of excitement has never before been witnessed in the district. On inquiries being made, however, it was found that the accident was not quite so serious as was originally reported, but it was, nevertheless, one of the most terrible that has ever happened in any of the works on the hills.

For a few years past the Dowlais Iron Company have been engaged in the construction of it new Bessemer department in the Lower Works, and it was hoped that it would be completed in another three or four months. A part of the new works has already been started. Meanwhile the old machinery has been used, and the ‘old Bessemer’ has remained in its usual condition. Massive stone walls enclose the works, the roof was constructed of slate supported by massive iron girders. About, twenty minutes to six o’clock this evening the roof gave way, with terrible results. One of the men who were at the cranes says that at the time he was working, when he heard a creaking in the roof. Looking up he saw that the roof was gradually giving way, and he at once took shelter under one of the pieces of machinery.

About 70 or 80 men were working in the place at the time. Fortunately for them, the roof did not give way at once, otherwise they would all have been killed. As it was, the ledge of the roof, after falling from its supports, rested for a few a seconds on the top of the cranes and hydraulic machinery, and thus enabled the men to escape. They dashed out of the building, but although the majority escaped uninjured several were struck by falling slates and were injured more or less severely. One young man, named John Morgan, who was ‘teeming’ at the time, saw the roof giving way, and thinking to escape more rapidly than his companions, he rushed towards the cogging mill. He had not gone more than a few yards when the roof fell in with a terrible crash. Nothing more was seen of him until nearly two hours later.

As soon as it was deemed safe to do so, men were sent to explore the debris with the view of ascertaining whether any serious loss of life bad taken place. Several tons of debris lay about in all directions, and for a long time it was impossible to make any headway. At last one of the men struck his spade against something, and on removing the debris it was found that the body of a man lay beneath one of the massive iron girders which supported the roof. By the aid of screw-jacks the girder was removed, and Morgan was brought out quite dead. It was ascertained that one of the pieces of iron which had fallen with the slates had penetrated the poor fellow’s side, and he had also sustained other frightful injuries. Morgan leaves a young widow and a child aged only nine weeks. It is believed that Morgan’s is the only life that has been lost, but several other workmen received injuries of a more or less serious character, and have had to be surgically treated.

The loss sustained by the Dowlais Iron Company must be estimated at several thousand pounds. Nearly all the hydraulic machinery and the cranes have either been destroyed or considerably damaged. At the time of the accident the vessels were full of molten iron, and in the confusion and excitement which followed the catastrophe the contents could not be emptied. The iron has therefore cooled, and cannot again be extracted from the vessels, which are rendered useless and will have to be blown up by dynamite. Nor can the effect of the accident upon the workmen be as yet correctly stated. All the branches of the steelworks must necessarily remain idle until the Bessemer department is again put into proper working order. Several hundreds of men have been thrown out of employment and some weeks will certainly elapse before things can be put to rights again.

The cause of the accident is very simple. The iron girders naturally contract and wear away under the influence of such terrific heat as continually prevails in the Bessemer department. The recent severe weather has, moreover, been most disastrous to buildings of this kind.

The Bessemer Process – part two

We continue with Alan Banks’ fascinating article about the Bessemer process:

Bessemer first started working with an ordinary reverbatory furnace but during a test a couple of pig ingots got off to the side of ladle and were sitting above it in the hot air of the furnace. When Bessemer went to push them into the ladle he found that they were steel shells: the hot air alone had converted the outer parts of the ingots 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, but due to exothermic oxidation both the silicon and carbon react with the excess oxygen leaving the surrounding molten iron even hotter, facilitating the conversion to steel.

Bessemer licenced the patent for his process to five ironmasters, for a total of £27,000, but the licences failed to produce the quality of steel he had promised and he later bought them back for £32,500. He realised the 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 had been burnt 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

The simple, but elegant, solution was first discovered by English metallurgist Robert Forester Mushet, who had carried out thousands of scientifically valid 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 uses.

The Dowlais Iron Company was the first licensee of the Bessemer process, constructing the world’s most powerful rolling mill in 1857, and producing its first Bessemer steel in 1865.

The Bessemer Plant at Dowlais Ironworks in 1896

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 labour requirements for steelmaking.

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. After the introduction of the Bessemer process, steel and wrought iron became similarly priced, and most manufacturers turned to steel. The availability of cheap steel allowed large bridges to be built and enabled the construction of railways, skyscrapers, and large ships.

Other important steel products 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 perfected by the Englishman Henry Bessemer paved the way to mass industrialisation as observed in the 19th-20th centuries.

Obsolescence

Commercial steel production using this method stopped in Workington in 1974. It was replaced by processes such as the basic oxygen (Linz-Donawitz) process, 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 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.

Many thanks to the Wirral Model Engineering Society for this article
http://www.wirralmodelengineeringsociety.co.uk/index.html

The Bessemer Process – part one

Quite often when you study Merthyr’s industrial history, you will hear about ‘The Bessemer Process’. If, like me, it is a mystery to you, here is an excellent article (in two parts), courtesy of Alan Banks of the Wirral Model Engineering Society explaining the mysteries of the process.

The Bessemer Process

The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron. The process is named after its inventor, Henry Bessemer, who took out a patent on the process in 1855. 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.

The process is carried on in a large ovoid steel container lined with clay or dolomite called the Bessemer converter. The capacity of a converter was from 8 to 30 tons of molten iron with a usual charge being around 15 tons. At the top of the converter is an opening, usually tilted to the side relative to the body of the vessel, through which the iron is introduced and the finished product removed. The bottom is perforated with a number of channels called tuyères through which air is forced into the converter. The converter is pivoted on trunnions so that it can be rotated to receive the charge, turned upright during conversion, and then rotated again for pouring out the molten steel at the end.

Oxidation

The oxidation process removes impurities such as silicon, manganese, and carbon 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 Bessemer, in which there is low phosphorus in the raw material. Dolomite is used when the phosphorus content is high in the basic Bessemer (limestone or magnesite linings are also sometimes used instead of dolomite). 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 (an ironcarbon-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.

After the blow, the liquid metal was recarburized to the desired point and other alloying materials are added, depending on the desired product. Before the Bessemer process, Britain had no practical method of reducing the carbon content of pig iron. Steel was manufactured by the reverse process of adding carbon to carbon-free wrought iron, usually imported from Sweden.

The manufacturing process, called 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. 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 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 1700s with the introduction of Benjamin Huntsman’s crucible steel-making technique, 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.

Sir Henry Bessemer described the origin of his invention in his autobiography. According to this book at the time of the outbreak of the Crimean War 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 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- Etienne 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 castiron 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 and by October he filed his first patent related to the Bessemer process.

To be continued……

Many thanks to the Wirral Model Engineering Society for this article
http://www.wirralmodelengineeringsociety.co.uk/index.html

The Puddler

Many thanks to prominent local historian Joe England for the following article:-

The Puddler

Who or what was the Puddler? He (always male) was a worker who in his day was central to the making of iron and a person of some importance in Merthyr and the other iron towns.

One writer reminisces: ‘One puddler I knew at Dowlais filled the chapel with his presence . . . a Cyfarthfa man stood in the Star parlour with his coat tails to the fire in the presence of Admiral Lord Nelson … another of the species used regularly every week to ride down to the seat of an influential county gentleman whose daughter he came very near marrying . . . it was by the merest accident in the world they found out, just in the nick of time, that the son-in-law elect was only a puddler.’

Puddling was a method of turning pig iron into much more malleable wrought iron. It was invented by Henry Cort but perfected by Richard Crawshay at Cyfarthfa in the 1790s. The puddler stirred the molten metal in a puddling furnace with an iron bar, working in conditions of tremendous heat and agitating the metal as it boiled and then gathering it at the end of a rod while the molten metal thickened.

This was arduous, strength-sapping work, but the puddler’s special skill was his judgement of when to bring out the congealing metal, a decision crucial to the quality of the finished product. He therefore held a key position in the manufacture of iron. They were usually young men in their twenties and thirties. By their forties they were physically burnt out.

In the early years of industrialisation their key position in the manufacture of iron made them workplace militants, although later they accepted the wage cuts imposed by the ironmasters. The reasons for that I have explained in my forthcoming book The Crucible of Modern Wales: Merthyr Tydfil 1760-1912. But the masters, nonetheless, were determined to find ways of getting rid of them. Puddlers were expensive and too powerful.

The opportunity came with the Bessemer process of making steel which would replace wrought iron in making rails. When the first steel rail was rolled at Dowlais in 1858 it broke while still hot ‘to the undisguised rejoicing of the assembled puddlers.’ But the writing was on the wall. Steel rails began to be successfully manufactured and by 1876 the iron rail was seen as a thing of the past. So was puddling. In 1885 the number of puddling forges at Dowlais was 19. There once had been 255.

Joe England