ARGON-OXYGEN DECARBURIZATION PDF
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) Treatment is the recognized standard for stainless steel refining worldwide. Whether you are producing castings, wrought . Argon Oxygen Decarburization, frequently referred to as “AOD”, is an advanced technology for the refinement of iron, nickel, and cobalt based alloys. By.
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AOD process uses dilution technique for the decarburization of steel bath.
During the oxygen blow, silicon is oxidized before carbon. The formation of a high basicity slag and the reduction of oxygen potential in the metal bath are good conditions for sulfur removal. Want to modernize and upgrade the functionality of your old AOD system cost-effectively?
The intimate gas — metal contact and excellent slag — metal mixing facilitate refining reactions. Nitrogen control is a gas — metal reaction. After initial melting the metal is then transferred to an AOD vessel where it will decaarburization subjected to three steps of refining; decarburizationreductionand desulphurization.
To drive the reaction to the forming of CO, the partial pressure of CO is lowered using argon or nitrogen. For converters that tap into a ladle held by a crane, a sliced cone top section is often used. Posted by Satyendra on Apr 28, in Technical 1 comment. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a heat. So, additions of lime are added to dilute sulfur in the metal bath.
After the change decwrburization nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon. Additional silicon addition is needed if requirement of silicon is there to meet the silicon specification of argkn-oxygen of the stainless decarburizatikn.
During the final stage of blowing, the ratio of oxygen to argon is changed to 1: Refractory costs are a significant fraction of total operating costs. There are usually two to four tuyeres in the bottom. Also, aluminum or silicon may be added to remove oxygen.
The liquid steel and the fluxes are then mixed to complete the desulfurization reaction. Decarurization modern practices a sulphur level of 0. Donate Grateful for your donation! Lime and dolomitic lime are sometimes added before the end of the blow to cool the bath and to reduce the volume of reduction additions.
At this point, the process gases can be shut off and a small cooling flow protects the tuyeres. While typical BOF refractory campaigns are months or years long, stainless converter campaigns are several days or weeks long.
The ratios can be done in any number of phases to facilitate the reaction. Other trimming alloy additions might be added at the end of the step. In case of arhon-oxygen steel grades which can tolerate nitrogen, a mixture of oxygen and nitrogen can also be blown.
The blow is continued to attain 0. Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form. Magnesite chromite bricks are simultaneously acidic and basic and strict slag compositions must be maintained to prevent rapid wear. In the initial stage, oxygen to argon in the ratio ranging from 5: Views Read Edit View history.
This is done in a ladle equipped with stirring facilities with or without the use of a ladle furnace. Tuyere size decarburizagion number depend on specific process parameters. The bath is then stirred with inert gas, typically for around five to eight minutes.
This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium.
For more Praxair videos, please visit our YouTube channel. 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. This page was last edited on 4 Octoberat The reduction mix also includes lime CaO and fluorspar CaF 2.
Argon-oxygen decarburization | metallurgy |
Annealing Low hydrogen Short circuit. Usually, the converter is turned down to a horizontal position and a sample of the liquid steel is taken for analyses at a carbon level of about 0.
After the transfer of liquid steel containing iron, chromium, carbon and nickel from EAF or IF to the AOD converter, high carbon ferro chrome is added and the blow is started with the blowing of inert gas argon, nitrogen and oxygen mixture. The choice of refractory is dependent on the vessel operation pattern, final product specifications, and economics. This accretion protects the tuyere and surrounding refractory.
Argon Oxygen Decarburization Process |
From Wikipedia, the free encyclopedia. In the early days of the AOD process, the converter was tilted for raw material additions as well as for taking samples and for measurement of temperature using immersion decarnurization. The top lance can also be designed for blowing mixed gases such as inert gas — oxygen mixtures.