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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This is done in a ladle equipped with stirring facilities with or without the use of a ladle furnace. The amount of stirring energy from the gas proxess through the subsurface tuyeres and the decarburizatlon of the carbon monoxide deep within the metal bath results in the converter processes being among the most intensely stirred metallurgical reactors.
This article needs additional citations for verification. After sulphur levels have been achieved the slag is removed from the AOD vessel and the metal bath is ready for tapping.
The slice portion allows the crane to come close to the converter mouth. Want to modernize and upgrade the functionality of your old AOD system cost-effectively? 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.
The liquid steel and the fluxes are then mixed to complete the desulfurization reaction.
At this point, the process gases can be shut off and a small cooling flow protects the tuyeres. Leave a Reply Cancel reply Your email address will not be published. November Learn how and when to remove this template message.
History of ferrous metallurgy List of steel producers. During decarburization, additions are made for obtaining the proper final chemical composition.
Send a question or comment. Additions of lime are made to dilute the sulphur in the liquid steel bath. There are usually between two and nine tuyeres in an AOD vessel. Decarburization time ranges decarburizxtion 20 to 35 minutes in modern converters start from 1.
Argon-oxygen decarburization | metallurgy |
Depending on final nitrogen specification for the stainless steel grade, the inert gas during the initial stages of decarburization can be nitrogen.
A major modification of the AOD process involves the use of top blowing lance in addition to the side blowing tuyeres. The reduction mix also includes lime CaO and fluorspar CaF 2. This accretion protects the tuyere and surrounding refractory. If the grade to be produced requires an extra low sulphur level, the bath is deslagged after the reduction step and another basic slag is added. The ratio is lowered with the progress of the decarburization.
Views Read Edit View pgocess. These are achieved by having a high lime concentration in the slag and a low oxygen activity in the metal bath. Converters that tap into a ladle car usually have a BOF type concentric cone top section.
Nitrogen control is a gas — metal reaction. This page was last edited on 4 Octoberat Converters are typically zoned by thickness and brick quality to maximize lining life and minimize costs. Modern instrumentation has been developed which can take melt samples as well as steel temperatures using a specially designed sub lance with the converter in the upright position.
The converter in the trunnion ring typically can be replaced with a preheated converter in less than an hour. As molten stainless steels do not generate foam, and most stainless steel refining processes are side or bottom-blown, the dimensions of a stainless refining converter are smaller than a comparable BOF basic oxygen furnace converter.
The decarburization reactions are as follow.
Argon oxygen decarburization – Wikipedia
Bottom injection usually improves wear characteristics in the barrel section of the converter. Bottom blown converters have a variety of tuyere configurations depending on flow rates required. Annealing Low hydrogen Short circuit. This is due to the very low oxygen potential of the gas mixture, which minimizes chromium oxidation. After initial melting the metal is then transferred to an AOD vessel where it will be subjected to three steps of refining; decarburizationreductionand desulphurization.
Typical internal volumes of AOD converters are in the range 0.
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After the ladle treatment, the steel is ready to be cast. Magnesite chromite bricks are simultaneously acidic and basic and strict slag compositions must be maintained to prevent rapid wear. An annulus is formed between the copper and stainless tubes.
Such an approach is usually practiced by steelmakers to reduce argon usage and costs and still achieve a desired nitrogen specification. To drive the reaction to the forming of CO, the partial pressure of Decarbhrization is lowered using argon or nitrogen. Additional silicon addition is needed if requirement of silicon is there to meet the silicon specification of some of the stainless steels.