Argon Oxygen Decarburization (AOD) Treatment is the recognized standard for stainless steel refining worldwide. Whether you are producing castings, wrought . Argon-oxygen decarburization: stainless steel: In the argon-oxygen decarburization process, a mixture of oxygen and argon gas is injected into the liquid steel. Argon Oxygen Decarburization, frequently referred to as “AOD”, is an advanced technology for the refinement of iron, nickel, and cobalt based alloys. By.
|Published (Last):||6 July 2015|
|PDF File Size:||5.35 Mb|
|ePub File Size:||3.20 Mb|
|Price:||Free* [*Free Regsitration Required]|
Dolomitic refractories are usually less costly than magnesite chromite refractories and chromium pickup is decarbueization a factor. In general, the bath temperature is controlled to less than deg C.
Chromium pickup from the brick is possible. After the change from nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon. A major decarburizatiob of the AOD process involves the use of top blowing lance in addition to the side blowing tuyeres. Refractory costs are a significant fraction of total operating costs.
The decarburization reactions are as follow. Careful manipulation of slag, as it precipitates in the reaction, is important. Bloomery produces sponge iron Blast furnace produces pig iron Cold blast Hot blast Anthracite iron Direct reduced iron. Bottom injection usually improves wear characteristics in the barrel section of the converter. High temperatures at the tuyere tip and high bath agitation place great deczrburization on the converters refractory.
The desire to increase the productivity has led to continuous charging of raw materials during the blow period as well as reduction period.
Side wall argno usually imparts maximum stirring energy to the bath for greatest efficiency of mixing. There are usually between two decarbruization nine tuyeres in an AOD vessel.
Donate Grateful for your donation! Phosphorus, which requires oxidizing conditions, cannot be removed in the converter processing.
Argon Oxygen Decarburization for Metal Production | Praxair, Inc.
The amount of stirring energy from the gas blown through the subsurface tuyeres and the formation of the carbon monoxide deep within the metal bath results in the converter processes being among the most intensely stirred metallurgical reactors. Process gases are injected through submerged tuyeres that are installed in the side wall or bottom of the converter.
This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. 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.
Cooling gases blown through the outer annulus shroud form a metal or oxide accretion called a mushroom at the tuyere tip. Most of the recent converter installations include the use of a top lance for blowing oxygen. The end result is a cleaner metal coupled with increased productivity. 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.
The process is very popular because it combines higher metallic yields with lower material costs. Reduction recovers the oxidized elements such as chromium from the slag. Views Read Edit View history. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a heat. Any chromium oxide not reduced by carbon ends up in the slag, which can form a complex spinel.
Leave a Reply Cancel reply Your email argom will not be published. Additions of lime are made oxyfen dilute the sulphur in the liquid steel bath.
While typical BOF refractory campaigns are months or years long, stainless converter campaigns are several days or weeks long.
Argon Oxygen Decarburization Process
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. In the initial stage, oxygen to argon in the ratio ranging from 5: Desulphurization to very low levels is generally easier in dolomitic refractories because very basic slags can be used without detrimental effects on the bricks.
The transfer of sulphur to slag takes place as per the following reaction. The gas control system supplies the process gases at nominal rates of 1.
Other benefits include pinpoint accuracy in chemistry control down to 0. It has a removable, conical cover in place.
Would like to more details of how to increase vessel life and to reduce refractory wear near tuyers. Bottom blown converters have a variety of tuyere configurations depending on flow rates required.
Praxair can review your system and design an upgrade using: