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open hearth furnace wikipedia jump to content main menu main menu move to sidebar hide navigation main page contents current events random article about wikipedia contact us contribute help learn to edit community portal recent changes upload file special pages search search appearance donate create account log in personal tools donate create account log in contents move to sidebar hide top 1 open hearth process 2 history toggle history subsection 2 1 decline and current operations 3 see also 4 references 5 further reading 6 external links toggle the table of contents open hearth furnace 32 languages العربية беларуская català čeština dansk deutsch esperanto español euskara فارسی suomi français gaeilge galego hrvatski magyar հայերեն italiano 日本語 ქართული қазақша 한국어 nederlands polski português русский srpskohrvatski српскохрватски svenska türkçe українська oʻzbekcha ўзбекча 中文 edit links article talk english read edit view history tools tools move to sidebar hide actions read edit view history general what links here related changes upload file permanent link page information cite this page get shortened url switch to legacy parser print export download as pdf printable version in other projects wikimedia commons wikidata item appearance move to sidebar hide from wikipedia the free encyclopedia redirected from open hearth furnace industrial furnace for steelmaking open hearth redirects here for an open hearth in the home see hearth open hearth furnace workers at the zaporizhstal steel mill in ukraine taking a steel sample c 2012 tapping open hearth furnace veb rohrkombinat riesa east germany 1982 an open hearth furnace is any of several kinds of industrial furnace in which excess carbon and other impurities are burnt out of pig iron to produce steel 1 because steel is difficult to manufacture owing to its high melting point normal fuels and furnaces were insufficient for mass production of steel and the open hearth type of furnace was one of several technologies developed in the nineteenth century to overcome this difficulty compared with the bessemer process which it displaced its main advantages were that it did not embrittle the steel from excessive nitrogen exposure clarification needed was easier to control and permitted the melting and refining of large amounts of scrap iron and steel 2 the open hearth furnace was first developed by german british engineer carl wilhelm siemens in 1865 the french engineer pierre émile martin took out a licence from siemens and first applied his regenerative furnace for making steel their process was known as the siemens martin process or martin siemens process and the furnace as an open hearth furnace most open hearth furnaces were shut down by the early 1990s not least because of their slow operation being replaced by the basic oxygen furnace or electric arc furnace 2 whereas the earliest example of open hearth steelmaking is found about 2000 years ago in the culture of the haya people in present day tanzania 3 and in europe in the catalan forge invented in spain in the 8th century it is usual to confine the term to certain 19th century and later steelmaking processes thus excluding bloomeries including the catalan forge finery forges and puddling furnaces from its application open hearth process edit the open hearth process is a batch process and a batch is called a heat the furnace is first inspected for possible damage once it is ready or repaired it is charged with light scrap such as sheet metal shredded vehicles or waste metal the furnace is heated using burning gas once the charge has melted heavy scrap such as building construction or steel milling scrap is added together with pig iron from blast furnaces once all the steel has melted slag forming agents such as limestone are added atmospheric oxygen in contact with molten pig iron directly oxidizes excess carbon it contains to form carbon monoxide co additionally fe ii present in iron ii oxide feo and other impurities also contribute to decarburize the pig iron by oxidizing carbon into co and simultaneously reducing fe ii into metallic fe the formed carbon monoxide co is flushed away in the fumes while steel is formed to increase the oxidizing power of the heat more iron oxide ore can be added 4 the process is far slower than that of the bessemer converter and thus easier to control and sample for quality assessment preparing a heat usually takes eight to eight and a half hours and longer to finish the conversion into steel as the process is slow it is not necessary to burn all the carbon away as in the bessemer process but the process can be terminated at any given point when the desired carbon content has been achieved 4 the furnace is tapped in the same way a blast furnace is tapped a hole is drilled in the side of the hearth and the raw steel flows out once all the steel has been tapped the slag is skimmed away the raw steel may be cast into ingots a process called teeming or it may be used in continuous casting in the rolling mill 4 the regenerators are the distinctive feature of the furnace and consist of fire brick flues filled with bricks set on edge and arranged in such a way as to have a great number of small passages between them 4 the bricks absorb most of the heat from the outgoing waste gases and return it later to the incoming cold gases for combustion history edit tapping open hearth furnace fagersta steelmill sweden 1967 carl wilhelm siemens developed the siemens regenerative furnace in the 1850s and claimed in 1857 to be recovering enough heat to save 70 80 of the fuel this furnace operates at a high temperature by using regenerative preheating of fuel and air for combustion in regenerative preheating the exhaust gases from the furnace are pumped into a chamber containing bricks where heat is transferred from the gases to the bricks the flow of the furnace is then reversed so that fuel and air pass through the chamber and are heated by the bricks through this method an open hearth furnace can reach temperatures high enough to melt steel but siemens did not initially use it for that 5 in 1865 the french engineer pierre émile martin took out a license from siemens and first applied his regenerative furnace for making steel the most appealing characteristic of the siemens regenerative furnace is the rapid production of large quantities of basic steel used for example to construct high rise buildings 5 the usual size of furnaces is 50 to 100 tons but for some special processes they may have a capacity of 250 or even 500 tons siemens furnace from 1895 30 ton siemens martin furnace section 1917 evolution of the size of open hearth furnaces the siemens martin process complemented rather than replaced the bessemer process it is slower and thus easier to control allowing production of better product it also permits the melting and refining of large amounts of scrap steel further lowering steel production costs and recycling an otherwise troublesome waste material one of its important drawbacks is that melting and refining a charge takes several hours this was an advantage in the early 20th century as it gave plant chemists time to analyze the steel and decide how much longer to refine it but by about 1975 electronic instruments such as atomic absorption spectrophotometers had made analysis of the steel much easier and faster the work environment around an open hearth furnace is said to be extremely dangerous although that may be even more true of the environment around a basic oxygen or electric arc furnace 5 on the one hand the process achieves lesser economies of scale than the bessemer so its steel was costlier in former s heyday but on the other it was more suitable for countries which couldn t produce lots of steel anyway due to limitations of natural resources 6 russian engineers invented the twin hearth furnace in the mid 20th century it has two melting pools separated by a brick wall and no regenerator chambers instead the furnace has direct burners and oxygen lances at the ceiling of the furnace the idea is to process two heats simultaneously but in different phases e g when one is being charged the other is being decarburized the idea is to burn away excess carbon and impurities with oxygen blast instead of free flame formation all reactions which occur are exothermic so the burners have only an auxiliary role 7 this is similar as the ajax furnace which also uses oxygen blow instead of free flame formation and regenerator chambers decline and current operations edit basic oxygen steelmaking eventually replaced the open hearth furnace it rapidly superseded both the bessemer and siemens martin processes in western europe from the 1950s and in eastern europe by the 1980s open hearth steelmaking had superseded the bessemer process in uk by 1900 but elsewhere in europe especially in germany the bessemer and thomas processes were used until the late 1960s when they were superseded by basic oxygen steelmaking the last open hearth furnace in former east germany was stopped in 1993 in the us steel production using the bessemer process ended in 1968 and the open hearth furnaces had stopped by 1992 in hunedoara steel works romania the last 420 tonne capacity open hearth furnace was shut down on 12 june 1999 and demolished and scrapped between 2001 and 2003 but the eight smokestacks of the furnaces remained until february 2011 the last open hearth shop in china was shut down in 2001 the process in the form of twin hearth furnace was in use in india s steel authority of india bhilai steel plant and some parts of ukraine russia retired its last hearth furnace in march 2018 and was considering preserving it as a museum artifact india s sail shut it down in april 2020 with the advent of covid 19 because of nonavailability of manpower to run the labor intensive process 8 as of 2024 the largest steel mill in the world that still produces steel using open hearth furnaces is the zaporizhstal steel mill in central ukraine which has seven 500 ton capacity ohfs and one twin hearth furnace as well as four blast furnaces the availability of cheap fuel oil in large quantities as well as the ongoing invasion largely contribute to their profitability despite the slow process the high cost of upgrading to new furnace technologies is prohibitive 9 10 see also edit engineering portal bessemer process cementation metallurgy crucible steel methods of crucible steel production ajax furnace oxygen based open hearth process references edit k barraclough steelmaking 1850 1900 institute of metals london 1990 137 203 1 2 philippe mioche et l acier créa l europe matériaux pour l histoire de notre temps vol 47 1997 p 29 36 avery donald schmidt peter 1978 complex iron smelting and prehistoric culture in tanzania science 201 4361 1085 1089 bibcode 1978sci 201 1085s doi 10 1126 science 201 4361 1085 issn 0036 8075 jstor 1746308 pmid 17830304 s2cid 37926350 1 2 3 4 a study of the open hearth a treatise on the open hearth furnace and the manufacture of open hearth steel harbison walker refractories company 2015 102 pag isbn 1341212122 isbn 978 1341212123 1 2 3 basic open hearth steelmaking with supplement on oxygen in steelmaking third edition the seely w mudd series the american institute of mining metallurgical and petroleum engineers 1964 gerhard derge asin b00ijlrl40 sáez garcía miguel a 2017 business and state in the development of the steel industry in spain and italy c 1880 1929 business history 59 2 159 178 doi 10 1080 00076791 2016 1172570 hdl 10045 66416 s2cid 156562137 twin hearth furnace pptx chemistry science www slideshare net retrieved 2025 08 30 в россии закрывается последняя крупная мартеновская печь 6 march 2018 zaporizhstal iron and steel works archived from the original on 2024 01 04 retrieved 2024 10 17 energy efficiency and carbon dioxide emissions reduction opportunities in the u s iron and steel sector pdf archived from the original pdf on 2017 08 09 retrieved 2006 12 09 further reading edit barraclough k 1990 steelmaking 1850 1900 institute of metals london pp 137 203 gale w k v 1969 iron and steel longmans london pp 74 77 siemens c w june 1862 on a regenerative gas furnace as applied to glasshouses puddling heating etc proceedings of the institution of mechanical engineers 13 institution of mechanical engineers 21 26 doi 10 1243 pime_proc_1862_013_007_02 external links edit wikimedia commons has media related to open hearth furnaces precursors to the blast furnace administering doses of liquid iron to steel furnaces popular science february 1919 page 64 scanned by google books v t e iron and steel production history of ferrous metallurgy list of steel producers iron production ironworks smelting bloomery produces sponge iron blast furnace produces pig iron cold blast hot blast anthracite iron direct reduced iron secondary wrought iron via finery forge or reverberatory puddling furnace cast iron via cupola furnace or induction furnace steelmaking steel mill primary pre 1850 pattern welding crucible steel damascus steel wootz steel tatara furnace cementation process primary post 1850 bessemer process open hearth furnace electric arc furnace basic oxygen process secondary electro slag remelting vacuum arc remelting argon oxygen decarburization heat treatment methods annealing low hydrogen short circuit hardening case hardening ausforming boriding carbonitriding carburizing cryogenic ferritic nitrocarburizing induction nitriding precipitation quench polish quench tempering austempering martempering cryogenic treatment deburring deflashing hardening differential heat treatment decarburization forming gas post weld heat treatment quenching superplastic forming production by country bangladesh china india italy luxembourg nigeria taiwan united kingdom united states authority control databases national united states france bnf data japan israel other encyclopedia of modern ukraine yale lux retrieved from https en wikipedia org w index php title open hearth_furnace oldid 1375085563 categories steelmaking metallurgical furnaces hidden categories articles with short description short description is different from wikidata wikipedia articles needing clarification from march 2024 commons category link from wikidata this page was last edited on 15 september 2026 at 19 56 utc page was rendered with parsoid text is available under the creative commons attribution sharealike 4 0 license additional terms may apply by using this site you agree to the terms of use and privacy policy wikipedia is a registered trademark of the wikimedia foundation inc a non profit organization privacy policy about wikipedia disclaimers contact wikipedia legal safety contacts code of conduct developers statistics cookie statement mobile view search search toggle the table of contents open hearth furnace 32 languages add topic