8/20/2019 1580 Fifty Years of BOF

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Pneumatic, autothermicsteelmaking on a tonnagescale commenced in 1856

 when Henry Bessemer was award-ed British patent (No 1292) forair-blowing converters. Suitable atfirst only for haematite iron madefrom acid ores, the process wasextended some 23 years later when in 1879, Thomas SydneyGilchrist introduced a tar bonded

basic dolomite lining and basicslag to treat basic iron made fromthe more common phosphorusbearing European ores. Thisenabled the sulphur and phospho-rus content of the basic iron to beremoved in the slag. Seventy-four years after Bessemer, the large-scale pro-duction of oxygen by the Linde-Frankelprocess, in about 1930, provided the firstopportunity for tonnage use of oxygen insteelmaking – a proposal originally putforward by Bessemer, but one that wascommercially impracticable in his day.

Because of the high temperature of reaction of oxygen with liquid iron – tem-peratures as high as 2500°C result – it was

impossible to inject pure oxygen as areplacement for air by submerged blowinginto the melt as in the Bessemer andThomas processes. Thus, submergedblowing with oxygen-enriched air, oxygen with carbon dioxide or oxygen with steam, was practiced on a large scale at first. In1968, hydrocarbon-protected tuyeres weredeveloped and applied in large-scale oper-ation.2 These new hydrocarbon-protectedtuyeres, which relied on the endothermicreaction of the cracking of the gas to coolthe annular tuyere, were the first to enablesubmerged blowing with pure oxygen.

The most successful development inpneumatic steelmaking was the blowing of pure oxygen onto the surface of the ironmelt at supersonic speed using a water-cooled top-blowing lance.2,3,4 The firstcommercial heat with top-oxygen blowing was performed fifty years ago this year inDecember 1952 at Voest-Alpine in Linz, Austria, followed in the early Springof 1953 by Voest-Alpine’s plant inDonawitz, Austria. It is conjec-tured that the LD in the nameof this new steelmaking processstands for the two plants inLinz and Donawitz.

 A few years later (in 1956) thegrowing Voest in-plant engineer-ing department started building thefirst LD plant outside Austria, at Rourkelain India. The nucleus of this Voest engi-neering department grew further as the

number of the LD projects increased sub-stantially. These were the beginnings of Voest-Alpine Industrieanlagenbau GmbH& Co (VAI), with its headquarters in Linz,

a company whichtoday offers one of the world’s mostc o m p r e h e n s i v eranges of productsand services in thefield of metallurgicalengineering.

Fig 1 shows howthe methods of steelmaking have

changed since 1860,and includes a forecast to 2006. The lifecycles of the Bessemer, Thomas andOpen-Hearth process are plotted in thisdiagram. Fig 1 also shows the annualdevelopment of worldwide crude-steelproduction. The sharp increase in crude-steel output from 1945 is largely due to thesubstantial contribution of the LD processbetween 1960 and 1980. In this period, 363LD converters were started up.Numerically, this represented over half of all existing converters operating at thatperiod. The driving force for such rapidimplementation of the LD process was, incomparison to the open-hearth plants, dueto a reduction in investment cost by rough-

ly 40% and a decrease in operating costsby 50%. The much higher productivity andimproving steel quality also contributed tothe rapid emergence of the LD plants.5,6,7

The rapid implementation of theLD process has led to a

significant demand for con- verters and related

replacements, which willbe required in the future.

Fig 2 shows thestartups per year of LD

converters along withestimates of the annual

demand for converters. The aver-age useful converter life is roughly 25 years. In reality, life depends on many fac-

tors, such as parts replacements, mainte-nance, mode of operation, the earningsfrom steel sales (usually used for invest-ments), etc. VAI has designed and startedup a total of nearly 200 new and replac-

ment converters for carbonand stainless steel productionsince 1952.

In Western Europe, North America and Japan, most of the converters in operationhave a heat size that rangesbetween 150 and 200 tonnes,and in the other regions of the world, the heat size inmany plants ranges between

50 and 150 tonnes. The num-ber of converters installed worldwide is nearly 700.

Since 1980 only a moderate increase insteel production has been observed in LDsteelmaking; however, the output of theEAF plants have continued to increase to asignificant extent, which is a result of thelower investment in the entire EAF steel-making route (ie scrap based rather thanore based), improvements in the EAFprocess, improved steel quality, and the useof larger amounts of oxygen, as well as thehigh level of flexibility of the process.

References

1 Savard Lee: International Symposium of BathSmelting Oct 1992 Montreal Canada Edited by J K Brimacombe P J Mackey G J W Kor C Bickert and M

G Ranade2 Michaelis E: Geschichtliche Entwicklung und

 weltweite Einführung des LD-Verfahrens BHM 137(1992) 162-169

3 Primas K and Poferl G: Vom ersten LD-Stahlwerkder Welt zum heutigen LD-Stahlwerk 3 in Linz BHM137 (1992) 179-186

4 Wiesinger H Patuzzi A Pühringer O und Wallner F:Entwicklung und Stand der LD-Stahlwerksplanungund -einrichtung BHM 137 (1992) 187-196

5 Klingelhöfer H J Hoffmann K: 40 years LD steel-developments results and prospects MetallurgicalPlant and Technology Int 4/1992 80-84

6 Hiebler H and Krieger W: Die Metallurgie des LDProzesses BMH 137 (1992) 256-262

7 Okumura H Ohji M and Murakani S: Developmentof LD based technology for ordinary grade steel prod-ucts in Japan BHM 137 (1992) 279-297

 Abstracted from a paper by E Fritz(1), W Gebert(2) & NRamaseder(3). The authors are with Voest-AlpineIndustrieanlagenbau GmbH & Co, PO Box 4, A-4031Linz, Austria. (1) Vice President Technology; (2) VicePresident, Plant Integration, Steelmaking & EnvironmentalTechnologies, (3) Manager R&D.

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S t e e l T i m e s I n t e r n a t i o n a l J U L Y / A U G U S T 2 0 0 2

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Current developments inoxygen steelmaking by thesame authors are reported

in the ‘ Steelmaking’feature in this issue.

1 Steel production processes and crudesteel production 1860-2010

2 Number of converter start-ups per year and estimate of the demand for converters on thebasis of useful converter life

50 years of converter50 years of converter

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