Fotografie Haiko Hebig

Directory of Preserved
Bessemer, Thomas, OBM, Kaldo, LD
Steelmaking Converters

Revision 2021-09-19

Thomas converter, Dortmund, Germany
Moving the preserved Hörde works Thomas converter to its new display site,
Dortmund, Germany, 2010

The invention of the Bessemer and Thomas (basic Bessemer) steelmaking processes in 1856 and 1878 made steel available at quantity and low cost for the first time, triggering unprecedented economic growth. In these processes, air is blown from the bottom or the side of cyclindric vessels – converters – through molten pig iron in order to burn excess carbon and remove impurities from the iron. They were superseded by processes using pure oxygen and phased out mainly in favor of the LD/BOF process by the late 1970s.

Demolition of the Union works Thomas steel plant,
Dortmund, Germany, 2020

Line diagram of crude steel production in West Germany by process over time Hermann Brandi, August-Thyssen-Hütte, Duisburg 1974

Even though Thomas steelmaking played a crucial role in postwar Germany, France, Belgium, and Luxemburg, preservation of steel plants and steelmaking equipment is lacking, while protecting ironmaking equipment – blast furnaces – has become commonplace.
However, a number of Bessemer and Thomas converters has been preserved across the globe, covering this paramount technology from early days to obsolescence. This list is an attempt to catalog them.

Photo of a blowing Bessemer converter at Youngstown, USA, 1918

Bessemer and Thomas (Basic Bessemer)
— Upright converters
— Early converters
— Swedish converters
— Small converters
— Large converters
LD (Basic Oxygen/BOF)
Current demolitions of converters
Recently demolished converters

Converters are listed by type and then by current location.

Russia, Ukraine, and China are not covered yet by this list.

Bessemer and Thomas (Basic Bessemer)

31 converters known in total


Upright converters

No converter known

In its early years, the Bessemer process was performed in stationary cylindrical vessels with a ring of air nozzles in its lower part. There are two known replicas: one full size replica at Tekniska museet, Stockholm, Sweden, and one half size replica at Edsken near Hofors, Sweden, at the site of the first successful Bessemer blow in 1858.

Early converters

Three converters known

  1. UK: At Science Museum, London, from Barrow Haematite Steel Company, Barrow-in-Furness
  2. D: At Deutsches Museum, München, from Krupp, Essen
  3. AUT: At Technisches Museum, Wien, from Eisenwerk Turrach
Swedish Bessemer converters

Bottom-blown converters with narrow mouth, acidic lining, typically removable upper and lower cones and a tap weight of 3 to 4 tons as used exclusively in Sweden until 1965. A remarkable number of such converters is preserved:

Eleven converters known

  1. SWE: At Hagfors Järnverk, in its original location
  2. SWE: At Hagfors Järnverk, in its original location
  3. SWE: At Iggesunds Bruk, in its original location
  4. SWE: At Iggesunds Bruk, in its original location
  5. SWE: At Svartnäs Bruk, in its original location
  6. SWE: At Västanfors, from Västanfors bruk
  7. SWE: At Tekniska museet, Stockholm, from Västanfors bruk
  8. SWE: At Långshyttan, from Klosterverken Långshyttan
  9. SWE: At Forsbacka, from Forsbacka Bruk
  10. SWE: At Sandviken, from Sandvikens Järnverk
  11. SWE: At Högbo Bruk, from Sandvikens Järnverk
Small converters
(Baby Bessemer)

As used in foundries. Mostly side-blown converters (Tropenas) fed with hot metal from cupola furnaces.

Seven converters known

  1. D: At Henrichshütte museum, Hattingen, from Eisenwerk Rödinghausen, Menden-Lendringsen
  2. D: At DASA Working World Exhibition, Dortmund, from Stahl- und Tempergießerei Gustav Tücking, Hagen-Eckesey
  3. LUX: At Minett Park Fond-de-Gras
  4. BEL: At University of Leuven, from Usines Emile Henricot, Court-Saint-Etienne
  5. UK: At Summerlee Museum of Scottish Industrial Life, Coatbridge, Scotland, from Stewarts and Lloyds' Sun Foundry, Coatbridge
  6. NL: At TATA Ijmuiden, from DEMKA, Utrecht
  7. NOR: At Norsk Teknisk Museum, Oslo, from Strømmen Værksted, Strømmen
    Tropenas converter, first blow 29.04.1902. The foundry switched to arc furnaces in 1925, was spun off as Strømmen Stål in 1970 and shut down in 1978.
    At Norway's single integrated steel plant, Norsk Jernverk at Mo-i-Rana, three generations of converters were in use: first two 20 t DEMAG Bessemer converters from 1955 to 1961, then two 40 t DEMAG LD converters, and finally two 72 t LD converters from 1976/77 to 1989. Today, one 12 t AOD converter is in service at a Jørpeland foundry.
Large converters

As used in integrated steel plants for steelmaking at large scale. Bottom-blown and typically fed with hot metal from blast furnaces.

Nine converters known

  1. D: At Phoenixsee, Dortmund, from Hörder Verein (DHHU) Hermannshütte at the same siteTh
  2. LUX: At University of Luxemburg, from ARBED SchifflangeTh
  3. LUX: At Lycée Nic-Bieve, Dudelange, from ARBED DudelangeTh
  4. UK: At Kelham Island Museum, Sheffield, England, from Workington Iron and Steel, Moss Bay, WorkingtonBm
  5. CZ: At Mayrau colliery museum, Vinařice, previously at Vila Bachrovna, Kladno, from Vojtěšská huť (Koněv, formerly Prager Eisen-Industrie-Gesellschaft)Th
  6. USA: In Pittsburgh, PA, from A. M. Byers Company, Ambridge, PABm
  7. ARG: At Altos Hornos Zapla, Palpalá, from the same site
  8. ZA: At Mittal South Africa, Pretoria, from the same siteBm
  9. J: At Kawasaki City Museum, from Kawasaki Works, Nippon Kōkan KKTh
    There are two scale models of this converter, one at Kawasaki City Museum, and one at JFE Steel Keihin Works Amenity Center.

Bm – Acid Bessemer
Th – Basic Bessemer (Thomas)

Other notable scale models and replicas of Bessemer converters on display in museums include the 1/4 sized converter at Chiba Museum of Science and Industry, Japan. It was built by English company, Garmendale, with methods, tools, and materials available in the 1850s.

At Longwy, France, a simplified scale model of a converter exists that was used in the 1979 Les Flammes de l'espoir protests against factory closures.


Converters using pure oxygen blown from the bottom.
Developed in the late 1960s, a number of Thomas converters in Germany, Belgium, and France were retrofitted as OBM converters in attempts to extend the lifespan of existing Thomas steel plants.

Four converters known

  1. F: At Mine musée du Val de Fer, Neuves-Maisons, from Chiers-Châtillon (USINOR) Neuves-Maisons
  2. D: At Stahlwerk Thüringen, Unterwellenborn, from the same site, Maxhütte UnterwellenbornQEK
  3. D: At Stahlwerk Thüringen, Unterwellenborn, from the same site, Maxhütte UnterwellenbornQEK
  4. D: At Henrichshütte museum, Hattingen, from Maxhütte UnterwellenbornQEK

QEK – Qualitäts- und Edelstahlkombinat Brandenburg, GDR, a OBM variant


Rotating oxygen-blown converters.
Abandoned quickly in favor of non-rotating converters.

One converter known

  1. SWE: At Domnarvets Jernverk, Borlänge, from the same site
    There were one 30 t (1956) and two 70/80 t (1965) PINTSCH-BAMAG made industrial scale Kaldo furnaces in operation at Domnarvets Jernverk, Borlänge, Sweden, all with vessel exchange system. A 30 ton Kaldo converter was rebuilt into an OBM converter in 1974 and into a desulphurisation unit in 1978 before getting decommissioned in 1981. There were also 3 t and 30 t Dored pilots at Domnarvets, a direct reduction process based on Kaldo vessels. Kaldo converters were also installed at the two Swedish coastal steelworks, Luleå and Oxelösund, and in France, UK, and USA.

Two other steelmaking processes also made use of rotating vessels: The LD-Kaldo converter could be operated by both the LD and the Kaldo method. Two built, none preserved. The Rotor steelmaking process or Rotorstahl employed a long cylindrical converter called Graef Rotor furnace or Oberhausen Rotor furnace. Approximately nine built, none preserved.

There is a universal converter at the Luleå, Sweden, research lab that can be used to simulate, among many others, the Kaldo and the Rotovert processes.

Rotovert (Sweden) and Rotored (Italy) were experimental steelmaking processes with rotary vessels that did not reach industrial scale.

Kaldo converters are also used in non-ferrous metallurgy under the generic term Top Blown Rotary Converters (TBRC).

LD Converters
(Basic Oxygen Furnaces/BOF)

Converters using pure oxygen, primarily blown from the top.
Today's dominant type of steelmaking equipment.

Seven converters known

  1. D: At Henrichshütte museum, Hattingen, from the same site
  2. AUT: At VÖEST, Linz, from the same site
  3. AUT: At Technisches Museum, Wien, from VÖEST, Linz
  4. I: At Ilva/Italsider di Bagnoli, Naples, from the same site
  5. CAN: At Dominion Foundry and Steel Dofasco, Hamilton, ON, from the same site
  6. J: 1956 Yawata 5 ton pilot converter at Higashida Daiichi Blast Furnace No. 1 Historical Site Plaza, Kitakyushu, from the same site
  7. J: At Higashida Daiichi Blast Furnace No. 1 Historical Site Plaza, Kitakyushu

Current Demolitions
of Converters

Ongoing demolitions of steel plants with basic oxygen furnaces

Nine converters known

  1. 3×LD-HC at Espérance-Longdoz/ArcelorMittal Chertal, BEL
    First blow 16.05.1963, last blow August 2011. Started with 2x150t top-blown LD-AC converters, 3rd 150t converter added 1968, replaced by 3x210t combined-blown LD-HC converters 1985 at switch to oversea ores, at least one converter renewed since. Greenfield meltshop and original converters built by DEMAG.
    Demolition of the complete Chertal site comprising the BOF shop, continuous casters (1983–2011), and a 2,250 mm Sack/Schneider-Creusot hot strip mill (1963–2012) started 2021. Three auxiliary buildings and "about 20" torpedo ladle cars to be preserved.
    LD-AC = LD - ARBED - Centre National de Recherches Métallurgiques CRNM Liège, developed as OCP Oxygène Pur et Chaux Pulvérisée by CRNM and industrialized by ARBED: blowing of oxygen and pulverized lime from the top. The ARBED LD-AC pilot converter is preserved at Dudelange, see above.
    LD-HC = LD - Hainaut-Sambre - CRNM: Combined top and bottom blowing process with moderate stirring. Approximately 10% of the oxygen is blown through propane-cooled bottom tuyeres, combined with blowing of oxygen or oxygen and pulverized lime from the top. Developed and first introduced at Hainaut-Sambre Montignies in the early 1980s and subsequently deployed at all three Cockerill-Sambre BOF shops, Montignies, Seraing, and Chertal.
    Chertal replaced the 6x20t air-oxygen-steam (1953) modified basic Bessemer converters at Seraing, shop started 1908 with 3x12t converters, last blow 31.10.1968, remaining eastern end of the building demolished 2021.
    Added 2021-08-30, LD-HC definition expanded 2021-09-17.
  2. 3×BOS-BAP at British Steel BSC/SSI Lackenby, England, UK
    260 t capacity, started with two LD converters 1971, third converter added 1972, converters replaced in the 1990s, last overhaul 2011/2012, last blow 28.09.2015. Originally scheduled for demolition 2022–2024 as laid out in the South Tees Regeneration Master Plan, works on the meltshop started 08/2021 under an expedited plan. No plans to preserve buildings or equipment known.
    The Lackenby, Redcar, Cleveland, and South Bank integrated steelmaking sites will be cleared in full, with the exception of connecting road and rail infrastructure, an office building, Steel House, the Redcar Bulk Terminal for Capesize vessels, and the Teesside Beam Mill, a long products hot rolling mill now operated by Chinese Jingye Group's British Steel and supplied from Scunthorpe.
    The BOS-BAP or BSC-BAP Bath Agitation Process was jointly developed by British Steel and Hoogovens and deployed at all their basic oxygen shops.
    The Lackenby BOF shop replaced the Dorman Long open hearth shop situated at the opposite end of site. Started 1954 with 5x350 t tilting furnaces and 2x600 t active mixers, closed 1971, demolished 2004.
    Added 2021-04-08, expanded 2021-09-17.
  3. 3×LD at Steel Company of Canada/US Steel Hamilton, Ontario, CAN
    Started with 3x120 t converters 12/1971, converters and meltshop built by Dravo, converters replaced with 140 t vessels 1988, rated as 160 t from 1996, idled 10/2010, shut down 31.12.2013, decision reviewed 2018, demolition started 06/2021. No plans to preserve buildings or equipment known.
    The demolition is part of a remediation program of what Stelco calls "deferred lands", comprising the sinter plant (demolished 2020), E blast furnace (demolition started 07/2021), No. 6 coke oven battery, and BOF sites.
    Stelco is operating a coking plant, cold rolling, and finishing facilities at Hamilton. Hot strip rolling and steelmaking were shifted to the 1980-started greenfield Lake Erie Works at Nanticoke, Ontario, in 2007 and 2010, respectively.
    The Hamilton BOF shop replaced No. 2 open hearth shop and was run in conjunction with oxygen-enabled No. 3 open hearth shop until the 2x245 t BOF shop at Lake Erie Works came on stream and No. 3 was shut down as the last open hearth shop in Canada. Both Hamilton and Nanticoke employ(ed) pure top blowing.
    An early LD converter is preserved 1,400 m SE of the Stelco BOF shop at the No. 2 BOF shop of neighboring ArcelorMittal Dofasco. Stelco and Dofasco are located directly next to each other in Hamilton Harbour. Dofasco operated the first BOF shop in the Americas starting 1954, and the GHH-built converter is from that shop.
    Added 2021-07-31, expanded 2021-09-19.

Demolished Converters

Basic oxygen furnaces scrapped in recent steel plant demolitions

14 converters known

  1. 2021: 2×OXYVIT at Vítkovické železárny, Ostrava, CZ
    75 t bottom-blown converters with CO post combustion, built in-house 1981 (K1) and 1991 (K2), overhauled 1992 (K1), scrapped 02/2021. Only OXYVIT converters made.
  2. 2019: 3×KMS at Maxhütte, Sulzbach-Rosenberg, D
    Klöckner-Maxhütte-Stahl process, 70 t capacity, converters built 1975-1977 by VÖEST, last blow 24.09.2002, scrapped 11/2019.
  3. 2019: 2×LD at National Steel/ArcelorMittal, Weirton, West Virginia, USA
    320 t capacity, built 1975/77 and 1989 by VÖEST, scrapped 2019.
  4. 2019: 3×K-OBM at Forges de Thy-Marcinelle et Monceau/Duferco Carsid, Charleroi, BEL
    150 t bottom-blown converters with oxygen side tuyeres, converters and meltshop built by VÖEST-GHH, first blow 04/1976, last blow 11.11.2008, scrapped 2019.
    At nearby La Louvière, the Gustave Boël converter buildings were demolished in late 2020. The LD-AC converters (2x85 t 1967–71, 3x85 t 1971–1997) had already been scrapped earlier. This leaves no Thomas or oxygen steelmaking shop left in the Charleroi region. These were: the Thomas shops at Châtelineau, Couillet, Montignies-sur-Sambre (LD-AC retrofit), Monceau-sur-Sambre (OBM retrofit), Marchienne-au-Pont (OBM retrofit), Marcinelle, Clabecq, and La Louviere, the LD-AC shops at Montignies-sur-Sambre (LD-HC retrofit), Clabecq, and La Louvière, the LD-Kaldo shop at Marchienne-au-Pont, and the Marcinelle OBM shop.
    Today, all steelmaking in the region is EAF based. A 1x180 t Siemens-VAI AOD shop with one blowing stand and three vessels was launched at Châtelet in 2005.
  5. 2016: 2×LD at Ovako/FNsteel Koverhar, Hanko, FIN
    53 t capacity, converters built by VÖEST, meltshop built by Kölsch-Fölzer-Werke, first blow 26.11.1971, last blow 27.06.2012, scrapped 2016.
    Koverhar was one of three coke blast furnace shops and one of two basic oxygen steelmaking shops in Finland. Three new 125 t Primetals LD converters were installed at the other BOF site, Raahe, in 2015 and 2016, scheduled to be replaced by electric arc furnaces in the 2030/40s.
    There also are two large AOD converters and one mechanically similar CRC ferrochrome converter in operation at Tornio, a VODC converter at Tampere, and a small AOD converter at Karhula.
  6. 2016: 2×LD-CB/NSR at Nakayama Steel Works, Funamachi, Osaka, J
    105 t top oxygen, bottom nitrogen blown converters that were later used in a scrap melting process. Meltshop started 09/1975 with 2x70t LD converters. Replacement 2x105t converters started 07/1985, LD-CB operation –07/2002, NSR operation 09/2002–27.05.2010.
    In the LD-CB process developed by Nippon Steel Sakai, CO2 or N2 is bubbled through a single pipe bottom plug.
    In the NSR Nakayama Scrap Refining Process, the same converters were operated without hot metal: 100% scrap charges were melted by adding coke through the top. Funamachi was the only shop that employed this process.

There was a full-size replica of a basic oxygen furnace on public display at McLouth Steel, Trenton, Michigan, USA, between 05/1985 and 10/2020, marking the first use of the LD process in the United States at that site in 1954. It got scrapped during land remediation. Classified as replica 2021-09-17.

This Resource

This directory of preserved steelmaking converters is meant as a research aid. It is compiled by Haiko Hebig.

First published: 2020-05-20
Revision: 2021-09-19

Please send additions and corrections to my email address:

With special thanks to Lauri Holappa.


Revision 2021-09-19
- Expanded: Scrapping of LD converters at Hamilton, thanks Stephen Lechniak

Revision 2021-09-17
- Expanded: Scrapping of LD converter replica at Trenton
- Expanded: Scrapping of BOS-BAP converters at Lackenby
- Expanded: Scrapping of LD-HC converters at Chertal

Revision 2021-08-30
- Added: Scrapping of LD-HC converters at Chertal
- Updated: Location of Th converter at Dudelange, thanks Jean-Marie Ottelé

Revision 2021-07-31
- Added: Scrapping of LD converters at Hamilton

Revision 2021-06-16
- Added: Scale models of Kawasaki converter

Revision 2021-06-02
- Added: Scrapped LD-CB/NSR converters at Osaka

Revision 2021-05-20
- Added: Yawata pilot LD converter at Kitakyushu

Revision 2021-04-08
- Added: Scheduled scrapping at Lackenby
- Updated: Scrapping of OXYVIT converters at Vítkovice
- Updated: Type of converter at Pretoria

Revision 2020-12-02
- Expanded: Scrapped K-OBM converters Marcinelle
- Updated: Scrapped LD converters at Koverhar, thanks Lauri Holappa

Revision 2020-11-27
- Updated: Tropenas converter at Norsk Teknisk Museum

Revision 2020-11-22
- Added: Converter model used in Longwy protests in 1979
- Updated: Name of ferrochrome converter at Tornio

Revision 2020-11-16
- Added: Origin of converter at Neuves Maisons
- Updated: Type of converter at Neuves Maisons

Revision 2020-11-15
- Added: Scrapping of OXYVIT converters at Vítkovice
- Expanded: Section on upright converters

Revision 2020-11-13
- Added: Section on Swedish Bessemer converters

Revision 2020-11-07
- Expanded: Tropenas converter at Norsk Teknisk Museum

Revision 2020-11-06
- Expanded: Kaldo converter at Domnarvet

Revision 2020-11-03
- Added: Tropenas converter at Norsk Teknisk Museum
- Added: Scrapped LD converters at Weirton
- Added: Scrapped LD converters at Koverhar
- Expanded: Scrapped KMS converters at Maxhütte
- Expanded: Scrapped K-OBM converters at Carsid

Revision 2020-06-26
- Added: LD converter at VÖEST, Linz

Revision 2020-06-20
- Added: Rotovert, Rotored

Revision 2020-06-08
- Added: Thomas converter at Mayrau mining museum, thanks Tomáš Voldráb.

Revision 2020-05-28
- Added: Note on LD-Kaldo and Rotor converters
- Added: Section on recently demolished converters

Revision 2020-05-26
- Added: Origin of converter at Summerlee Museum
- Added: LD converter at Dofasco

Revision 2020-05-25
- Added: LD converter at Higashida Park
- Added: Thomas converter at Kawasaki City Museum
- Added: Scale model at Chiba museum

Revision 2020-05-23
- Added: Origin of converter at DASA Dortmund

Revision 2020-05-20
- Initial publication