Learn more about Praxair’s Argon Oxygen Decarburization process that is used to make over 75% of the world’s stainless steel. Argon oxygen decarburization (AOD) converter is popularly used in the stainless steel making process. AOD has a top lance for oxygen injection and several.
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From Wikipedia, the free encyclopedia. Bottom blown converters have a variety of tuyere configurations depending on flow rates required. The next step is the reduction step, in which the reduction additions are charged and stirred with an inert gas for a desired time.
afgon These additions also serve to reduce the bath temperature as carbon and chromium oxidations are exothermic. Argon oxygen decarburization for metal production Share Print. The key feature in the AOD converter is that oxygen for decarburization is mixed with inert gas such as argon or nitrogen and injected through submerged tuyeres. Please help improve this article by adding citations to reliable sources.
Donate Grateful for your donation! Unsourced material may be challenged and removed. This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. Careful manipulation of slag, as it precipitates in the reaction, is important. The gas control system supplies the process gases at nominal rates of 1.
Additions of lime are made to dilute the sulphur in the liquid steel bath. During the final stage of blowing, the ratio of oxygen to argon is changed to 1: The slice portion allows the crane to come close to the proocess mouth.
Argon oxygen decarburization – Wikipedia
Converters that tap into a ladle car usually have a BOF type concentric cone top section. In the initial stage, oxygen to argon in the ratio ranging from 5: It is part of a duplex process in which scrap or virgin raw materials are first melted in an electric arc furnace EAF or induction furnace IF. Magnesite chromite bricks are simultaneously acidic and basic and strict slag compositions must be maintained to prevent rapid wear.
After initial melting the metal is then transferred to an AOD vessel where it will be subjected to three steps of refining; decarburizationreductionand desulphurization. The decarburizxtion bath is then either sent to a stir station for further chemistry trimming or to a caster for casting.
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The choice of refractory is dependent on the vessel operation pattern, final product specifications, and economics. This page was last edited on 4 Octoberat There are two basic choices of refractory type, magnesite-chromite, and dolomite.
The length of the blow period is determined by the starting carbon and silicon levels of the hot metal charged to the AOD converter.
This is due to the very low oxygen potential of the gas mixture, which minimizes chromium oxidation. During the oxygen blow, silicon is oxidized before carbon. After the change from nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon.
The process is so popular because it combines higher metallic yields with lower material costs. The liquid metal is transferred from transfer ladle to AOD converter.
Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form. Decarburization time ranges from 20 to 35 minutes in modern converters start from 1. These tuyeres typically consist of a copper tube with a stainless steel outer tube. Want to modernize and upgrade the functionality of your old AOD system cost-effectively?
These are achieved by having a high lime concentration in the slag and a low oxygen activity in the metal bath. Views Read Edit View history. This argon dilution of oxygen minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. Another modification of the AOD process involves applying vacuum on the converter to reduce the consumption of argon and silicon as well as the process time when making low carbon grades.
Decarburization occurs on the surface of rising bubbles that form from either the inert gas that is injected or on the surface of chromium oxide particles that are being reduced and generating carbon mono oxide CO.