LINZ DONAWITZ PROCESS PDF

Horace identified steel weapons like the falcata in the Iberian Peninsula, while Noric steel was used by the Roman army. The steel technology existed prior to BCE in the region as they are mentioned in literature of Sangam Tamil, Arabic and Latin as the finest steel called Seric iron in the world exported to the Romans, Egyptian, Chinese and Arabs worlds at that time. Wootz, also known as Damascus steel, is famous for its durability and ability to hold an edge. As known from the writings of Zosimos of Panopolis, this steel was originally created from a number of different materials including various trace elements. It was essentially a complicated alloy with iron as its main component. Natural wind was used where the soil containing iron was heated by the use of wood.

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Horace identified steel weapons like the falcata in the Iberian Peninsula, while Noric steel was used by the Roman army. The steel technology existed prior to BCE in the region as they are mentioned in literature of Sangam Tamil, Arabic and Latin as the finest steel called Seric iron in the world exported to the Romans, Egyptian, Chinese and Arabs worlds at that time. Wootz, also known as Damascus steel, is famous for its durability and ability to hold an edge.

As known from the writings of Zosimos of Panopolis, this steel was originally created from a number of different materials including various trace elements.

It was essentially a complicated alloy with iron as its main component. Natural wind was used where the soil containing iron was heated by the use of wood. One such furnace was found in Samanalawewa and archaeologists were able to produce steel as the ancients did. Various methods were used to produce steel in Indian sub-continent.

According to Islamic texts such as al-Tarsusi and Abu Rayhan Biruni, three methods are described for indirect production of steel. He describes only three methods for producing steel. These three methods are generally considered to have originated from the Indian subcontinent.

The first method and the most common traditional method is solid state carburization of wrought iron. Another indirect method uses wrought iron and cast iron. In this process, wrought iron and cast iron may be heated together in a crucible to produce steel by fusion.

For the C, a variety of organic materials are specified by the contemporary Islamic authorities, including pomegranate rinds, acorns, fruit skins like orange peel, leaves as well as the white of egg and shells. Slivers of wood are mentioned in some of the Indian sources, but significantly none of the sources mention charcoal.

It was apparently developed before the 17th century. Derwentcote steel furnace, built in , is the earliest surviving example of a cementation furnace. The process begins with wrought iron and charcoal. Typically, each was 14 feet 4. Iron bars and charcoal are packed in alternating layers, with a top layer of charcoal and then refractory matter to make the pot airtight. In larger works, up to 16 tons of iron was treated in each cycle. Standard wrought iron bars were placed in the cementation furnace for conversion into cementation or blister steel.

The furnace was constructed from sandstone in the form of a large chest with a lid and was loaded with the iron bars placed in layers inter spaced with large quantities of high quality charcoal. When fully loaded, the lid was put in place and mortar use to seal the chest.

Heating was applied from a fire below the furnace where a coal fire was maintained from a pit. Heat was maintained for up to a week and a further week was taken for the chest to cool before being opened, emptied, and reloaded. The placing of two furnace chest together would allow the one fire to heat the first chest while the second was cooling and being reloaded. During the long slow heating C from the charcoal was absorbed into the iron bars. When removed from the furnace, the steel had a blistered appearance thus the alternative name.

These blisters contained steel with a high C content while the centre of the bars were still wrought iron with very little C, thus blister steel was of little if any use until it had been processed further. The blister steel was heated and forged under a hammer such that the bar was folded over on its self. A plan and elevation view of a typical cementation furnace is at Fig 1. Crucible steel was produced in South and Central Asia during the medieval era.

His process used iron and steel as raw materials. The homogeneous crystal structure of this cast steel improved its strength and hardness compared to preceding forms of steel. While crucible steel is more attributed to the Middle East in early times, there have been swords discovered in Europe, particularly in Scandinavia. These swords actually date in a year period from the 9th century to the early 11th century. In the first centuries of the Islamic period, there appear some scientific studies on swords and steel.

The best known of these are by Jabir ibn Ayyan 8th century , al-Kindi 9th century , Abu Rayhan Biruni early 11th century , Murda al Tarsusi late 12th century , and Fakhr-i-Mudabbir 13th century. Any of these contains far more information about Indian and damascene steels than appears in the entire literature of classical Greece and Rome.

He began producing steel in after years of experimenting in secret. Each workshop had a series of standard features, such as rows of melting holes, teeming pits, roof vents, rows of shelving for the crucible pots and annealing furnaces to prepare each pot before firing. Ancillary rooms for weighing each charge and for the manufacture of the clay crucibles were either attached to the workshop, or located within the cellar complex.

The steel, originally intended for making clock springs, was later used in other applications such as scissors, axes and swords. In another method, developed in the United States in the s, iron and C were melted together directly to produce crucible steel. The crucible process continued to be used for specialty steels, but is obsolete today.

Another form of crucible steel was developed in by the Russian engineer, Pavel Anosov. His technique relied less on the heating and cooling, and more on the quenching process of rapidly cooling the liquid steel when the right crystal structure had formed within. The secret of the process died with him. In the United States crucible steel was pioneered by William Metcalf. While crucible steel was very high quality, it was also expensive; however a sign of the quality was the use of crucible steel into the s for specialist uses.

The Bessemer process brought about the end of crucible steel for the less critical uses. The Bessemer process and modern steelmaking The history of modern steelmaking began in the 19th century, when Reaumur of France in , Kelly of the United States in and Bessemer of Britain in discovered how to improve on pig iron by controlling the carbon content of iron alloys, which thus truly become steels.

While Reaumur, a chemist, was driven by scientific curiosity, but Kerry and Bessemer being engineers, were responding to the need for larger quantities and better qualities of steel which the industrial revolution, with its looms, steam engines, machines and railroads, had created. This had started a dialectical relationship between science and technology and the basic concepts of refining hot metal pig iron by oxidizing C in a liquid bath were invented at that time.

Yet steel was still unproven as a structural metal and production was slow and costly. Starting in January , 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.

Bessemer first started working with an ordinary reverberatory 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 liquid 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 Si and C react with the excess O2 leaving the surrounding molten iron even hotter, facilitating the conversion to steel. As O2 passed through the liquid metal, it would react with the C, release carbon dioxide CO2 and produce a more pure iron. The Bessemer process was the first inexpensive industrial process for the mass-production of steel from liquid iron. The process is named after its inventor, Henry Bessemer, who took out a patent on the process in The key principle is removal of impurities from the iron by oxidation with air being blown through the liquid 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 tons to 30 tons of liquid 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 tuyeres 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 liquid steel at the end.

The oxidation process removes impurities such as Si, C, and manganese Mn 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 fireclay lining was used in the acid Bessemer, in which there is low phosphorus P in the raw material.

Dolomite is used when the P 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 liquid steel when conversion was complete, such as spiegeleisen an iron carbon- manganese alloy. 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.

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. 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.

Fig 2 shows the Bessemer converter. Fig 2 Bessemer converter Bessemer licensed the patent for his process to five ironmasters, for a total of GBP 27,, but the licenses failed to produce the quality of steel he had promised and he later bought them back for GBP 32, He realized 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 C 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 Robert Forester Mushet who had carried out thousands of scientifically valid experiments. His method was to first burn off, as far as possible, all the impurities and C, then reintroduce C and Mn by adding an exact amount of spiegeleisen. This had the effect of improving the quality of the finished product, increasing its malleability and its ability to withstand rolling and forging at high temperatures and making it more suitable for a vast array of uses.

The Bessemer process revolutionized steel manufacture by decreasing its cost, from GBP 40 per long ton to GBP 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 the introduction of Bessemer process, 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.

The introduction of the large scale steel production process perfected by the Englishman Henry Bessemer paved the way to mass industrialization as observed in the 19thth centuries. Commercial steel production using this method stopped in Workington in It was replaced by processes such as the basic oxygen 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 P efficiently from the liquid steel; as low-P ores became more expensive, conversion costs increased. The process permitted only limited amount of scrap steel to be charged, further increasing costs.

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Linz-Donawitz process

A milestone in the history of steel production. And a special reason for voestalpine to celebrate — for that is when this state-of-the-art company was founded. This was an important and major event for everyone involved, and also the start of the triumphant advance of the LD process: a method in which oxygen is blown through molten pig iron to convert it to steel. This process accelerated or first made it possible to combust the tramp elements from pig iron, which include carbon, manganese, phosphorous, sulfur, silicon, etc. Steel produced using the LD process is characterized by its purity and that it is fully recyclable — retaining its type and without loss of quality. By June, the first , tons of LD steel had been produced, and by the beginning of December , tons of steel had been smelted. And that was just the beginning.

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Nobody could have imagined then the breakthrough would take place here: an innova- tion that would revolutionize the production of steel. Uncertainties arose and there were massive differences of opinion, but a pioneering spirit prevailed and courageous decisions were taken. The Austrian steel industry, and more specifically the plants in Linz, expected great things from the new steel production process, and a start was also made without delay on marketing it abroad. These hopes were more than fulfilled.

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History[ edit ] The basic oxygen process developed outside of traditional "big steel" environment. It was developed and refined by a single man, Swiss engineer Robert Durrer, and commercialized by two small steel companies in allied-occupied Austria , which had not yet recovered from the destruction of World War II. For nearly years commercial quantities of oxygen were not available or were too expensive, and the invention remained unused. In he purchased the first small 2.

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