Argon oxygen decarburization: Difference between revisions

Revision as of 09:40, 30 October 2023

Revision as of 23:30, 27 March 2024

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{{Refimprove|date=November 2010}}

[[File:AOD (Argon, oxygen decarburisation) vessel.jpg|thumb|Refining of a 9.5%CrMoWVNbN steel in an argon, oxygen decarburisation (AOD) vessel]]

'''Argon oxygenArgonoxygen decarburization''' ('''AOD''') is a process primarily used in [[stainless steel]] [[steel making|making]] and other high grade alloys with oxidizable elements such as [[chromium]] and [[aluminium]]. After initial melting the metal is then transferred to an AOD vessel where it will be subjected to three steps of refining; [[decarburization]], [[Reduction (chemistry)|reduction]], and [[desulfurization]].

The AOD process was invented in 1954 by the Lindé Division of The [[Union Carbide Corporation]]<ref name=krivsky73>{{cite journal | doi = 10.1007/BF02667991| bibcode = 1973MT......4.1439K| title = The linde argon-oxygen process for stainless steel; A case study of major innovation in a basic industry| journal = Metallurgical Transactions| volume = 4| issue = 6| pages = 1439–1447| last1 = Krivsky| first1 = W. A.| year = 1973| s2cid = 135951136|url=https://link.springer.com/article/10.1007/BF02667991}}</ref><ref name=jalkanen14>{{cite journal |last1=Jalkanen |first1=Heikki |last2=Holappa |first2=Lauri |editor1-last=Seetharaman |editor1-first=Seshadri |title=Converter Steelmaking |journal=Treatise on Process Metallurgy: Industrial Processes |date=2014 |doi=10.1016/C2010-0-67121-5 |publisher=Elsevier|isbn=9780080969886 }}</ref> (which became known as [[Praxair]] in 1992).<ref name=uchist>[http://www.unioncarbide.com/History History] {{Webarchive|url=https://web.archive.org/web/20170609104241/http://www.unioncarbide.com/history |date=2017-06-09 }}. Unioncarbide.com (1917-11-01). Retrieved on 2013-12-28.</ref>

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Prior to the decarburization step, one more step should be taken into consideration: ''de-siliconization'', which is a very important factor for refractory lining and further refinement.

The decarburization step is controlled by ratios of [[oxygen]] to [[argon]] or [[nitrogen]] to remove the [[carbon]] from the metal bath. The ratios can be done in any number of phases to facilitate the reaction. The gases are usually blown through a top lance (oxygen only) and [[tuyere|tuyeres]] in the sides/bottom (oxygen with an inert gas shroud). The stages of blowing remove carbon by the combination of oxygen and carbon forming [[carbon monoxide|CO]] gas.

:4 Cr_(bath) + 3 O₂ → 2 Cr₂O_3(slag)