Posted on February 9, 2019

ARGON OXYGEN DECARBURIZATION PROCESS 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) converter is popularly used in the stainless steel making process. AOD has a top lance for oxygen injection and several.

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During decarburization, additions are made for obtaining the proper final chemical composition. The gas control system supplies the process gases at nominal rates of 1. The system accurately controls the flow rates and monitors the amount of gas injected argn the bath to enable the operator to control the process and measure the total oxygen injected.

The major benefit associated with the dilution process comes into play when the oxygen to inert gas ratio is 1: The liquid steel, which contains most of the chromium and nickel needed to meet the final heat composition, is tapped at a temperature of to deg C from the EAF or the IF into a transfer ladle. After a desired carbon and temperature level have been reached the process moves to reduction. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time oxyten a heat.

Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form. AOD provides an economical way to produce stainless steel with a minimal loss of precious elements. November Learn how and when to remove this template message. 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. AOD process refining has three major steps.

The AOD converter can be rotated downwards so that the side mounted tuyeres are above the bath level during charging of the liquid steel. Additions of lime are procezs to dilute the sulphur in the liquid steel bath.

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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.

During the final stage of blowing, the ratio of oxygen to argon is changed to 1: AOD converter decarburization refractories Side blown stainless steel.

Argon-oxygen decarburization | metallurgy |

High temperatures at the proceds tip and high bath agitation place great demands on the converters refractory. The formation of a high procrss slag and the reduction of oxygen potential in the metal bath are good conditions for sulfur removal.

Praxair can quote a server-only option for these systems. Argon oxygen decarburization AOD is a process primarily used in stainless steel making and other high grade alloys with oxidizable elements such as chromium and aluminum.

There are two basic choices of refractory type, magnesite-chromite, and dolomite. Careful manipulation of slag, as it precipitates in the reaction, is important.

Argon Oxygen Decarburization Process

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. Electro-slag remelting Vacuum arc remelting Argon oxygen decarburization. For converters that tap into a ladle held by a crane, a sliced cone top section is often used. 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. The important feature of an AOD converter is that it is normally side blown.

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. The top lance can also be designed for blowing mixed gases such as inert gas — oxygen mixtures. 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.

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The process is so popular because it combines higher metallic yields with lower material costs. Retrieved from ” https: The blow is continued to attain 0. Articles needing additional references from November All articles needing additional references. Desulphurization to very low levels is generally easier in dolomitic refractories because very basic slags can be used without detrimental effects on the bricks.

Side wall injection usually imparts maximum stirring energy to the bath for greatest efficiency of mixing. 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. The decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. The tapped bath is then either sent to a stir station for further chemistry trimming or to a caster for casting.

The liquid metal is transferred from transfer ladle to AOD converter. In case of those steel grades which can tolerate nitrogen, a mixture of oxygen and nitrogen can also be blown.

Chromium pickup from the brick is possible. From Wikipedia, the free encyclopedia. Process gases are decarburizatiion through submerged tuyeres that are installed in the side wall or bottom of the converter.