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

Revision 2020-06-26

Thomas converter, Dortmund, Germany
Moving the DHHU Thomas converter, Dortmund, Germany

The invention of the Bessemer and basic Bessemer (Thomas) processes in 1856 and 1878 meant steel could be made in large quantities and at low cost for the first time, resulting in significant economic impact. 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 They were superseded by oxygen-based processes from the mid 1950s on and phased out by the late 1970s.

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

While many modern ironmaking plants –blast furnaces– are listed as monuments, preservation of steelmaking equipment and processes is lacking. No complete Thomas shop is preserved, no Thomas converter is remaining in its original place, and related buildings and architectural traces are getting fewer.

However, a number of converters has been preserved across the globe, covering the entire lifespan of this paramount technology from early days to obsolescence. This list is an attempt to catalog them.

Bessemer and Thomas (Basic Bessemer)
— Early converters
— Small converters
— Large converters
LD (Basic Oxygen BOF)
Recently demolished converters

Converters are listed by type and then by current location.

Focus of this list is on Western Europe.
Sweden, Russia, Ukraine, and China are not covered.

Bessemer and Thomas (Basic Bessemer)

18 converters known


Early converters
  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
Small converters
(Baby Bessemer)

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

  1. D: At Henrichshütte Museum, Hattingen, from Eisenwerk Rödinghausen, Menden-Lendringsen
  2. D: At DASA Museum, 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 Sun Foundry (Stewarts and Lloyds), Coatbridge
  6. NL: At TATA Ijmuiden, from DEMKA, Utrecht
Large converters

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

  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: In Dudelange, from ARBED Dudelange, currently not on displayTh
  4. F: At Mine musée du Val de Fer, Neuves-MaisonsTh
  5. UK: At Kelham Island Museum, Sheffield, from Workington Iron and Steel, Moss Bay, WorkingtonBm
  6. CZ: At Mayrau colliery museum, Vinařice, previously at Vila Bachrovna, Kladno, from Vojtěšská huť (Koněv, formerly Prager Eisen-Industrie-Gesellschaft)Th
  7. USA: In Pittsburgh, PA, from A. M. Byers Company, Ambridge, PA
  8. ARG: At Altos Hornos Zapla, Palpalá, from the same site
  9. ZA: At Mittal South Africa, Pretoria, from the same site
  10. J: At Kawasaki City Museum, from NKK Keihin Steel WorksTh

Bm – Acid Bessemer
Th – Basic Bessemer (Thomas)

There also are scale models and replicas of Bessemer converters on display in museums. Notable ones include the 1/4 scale model at Chiba Museum of Science and Industry, Japan. It was built by English company, Garmendale, with methods, tools, and materials available in the 1850s.


Bottom-blown converters using pure oxygen. The converters listed here employ the QEK process (Qualitäts- und Edelstahlkombinat Brandenburg, GDR).

Three converters known

  1. D: At Stahlwerk Thüringen, Unterwellenborn, from the same site
  2. D: At Stahlwerk Thüringen, Unterwellenborn, from the same site
  3. D: At Henrichshütte Museum, Hattingen, from Stahlwerk Thüringen, Unterwellenborn


Rotating oxygen-blown converters

One converter known

  1. SWE: At Domnarvets Jernverk, Borlänge, from the same site

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

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. Approx. 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.

LD (Basic Oxygen BOF)

Primarily top-blown converters using pure oxygen

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. USA: At McLouth Steel Trenton, MI, from the same site
  6. CAN: At Dominion Foundry and Steel Dofasco, Hamilton, ON, from the same site
  7. J: At Higashida Daiichi Blast Furnace No. 1 Historical Site Plaza, Fukuoka

There also are cold idled converters and converters decomissioned in place.

Demolished Converters

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: 2020-06-26

Please send additions and corrections to my email address:


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

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
- Original publication