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.
This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. Volatile elements with high vapour pressures, such as lead, zinc, and bismuth, are removed during the decarburization period. Careful manipulation of slag, as it precipitates in the reaction, is important. This article needs additional citations for verification.
Bottom injection usually improves wear characteristics in the barrel section of the converter.
Other benefits of AOD process include pinpoint accuracy in chemistry control down to 0. 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 thermocouples. In the initial stage, oxygen to argon in the ratio ranging from 5: The formation of high basic slag and the reduction of oxygen potential in the liquid steel bath are good conditions for sulphur removal.
Ideally at this stage of the process, the chemistry of the liquid steel should meet the final specifications so that the heat can be tapped. Argon-oxgen decarburization decarbkrization is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. The argon-oxyggen feature of an AOD converter is that it is normally side blown.
Posted by Satyendra on Apr 28, in Technical 1 comment. Also, aluminum or silicon may be added to remove oxygen.
Praxair can review your system and design an upgrade using:. The addition of lime and fluorspar help argoon-oxygen driving the reduction of Cr 2 O 3 and managing the slag, keeping the slag fluid and volume small.
Unsourced material may be challenged and removed. Dolomitic refractories are usually less costly than magnesite chromite refractories and chromium pickup is not a factor. This accretion protects the tuyere and surrounding refractory.
Bottom blown converters have a variety of tuyere configurations depending on flow rates required. 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.
Articles needing additional references from November All articles decarbutization additional references. Magnesite chromite bricks are simultaneously acidic and basic and strict slag compositions must be maintained to prevent rapid wear. During decarburization, additions are made for obtaining the proper final argon-oxhgen composition.
Argon oxygen decarburization
For example, with starting sulphur of 0. An annulus is formed between the copper and stainless tubes.
There are two basic choices of refractory type, magnesite-chromite, and deczrburization. A major modification of the AOD process involves the use of top blowing lance in addition to the side blowing tuyeres. Side wall injection usually imparts maximum stirring energy to the bath for greatest efficiency of mixing.
For more Praxair videos, please visit our YouTube channel. The AOD converter has tuyeres mounted agron-oxygen the sidewall or in the bottom. This is done in a ladle equipped with stirring facilities with or without the use of a ladle furnace.
The major benefit associated with the dilution process comes into play when the oxygen to inert gas ratio is 1: Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form.
At any given time, one of the converters is in the tiltable trunnion ring refining steel, a second newly lined converter is at a preheating station, and the third converter is at a reline station. Such an approach is usually practiced by steelmakers to reduce argon usage and costs and still achieve a desired nitrogen specification.
This is due to the very low oxygen potential of the gas mixture, which minimizes chromium oxidation. Lime and dolomitic lime are sometimes added before the end of the blow to cool the adgon-oxygen and to reduce the volume of reduction additions. Also, aluminum or silicon may be added to remove oxygen.
Argon Oxygen Decarburization for Metal Production | Praxair, Inc.
These additions usually consist of desired amounts of high carbon ferrochromium, stainless steel scrap, carbon steel scrap, nickel, iron, high carbon ferromanganese, and molybdenum oxide. There are usually between two and nine tuyeres in an AOD vessel.
The top lance can also be designed for blowing mixed gases such as inert gas — oxygen mixtures. The liquid metal is transferred from transfer ladle to AOD converter. An AOD converter is shown in Fig 1. In general, the bath temperature is controlled to less than deg C. Your email address will not be published. For converters that tap into a ladle held by a crane, a sliced cone top section is often used.
Reduction recovers the oxidized elements such as chromium from the slag. Usually, the argon-oxyegn is turned down to a horizontal position and a sample decxrburization the liquid steel is taken for analyses at a carbon level of about 0. The desire to increase the productivity has led to continuous charging of raw materials during the blow period as well as reduction period.
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