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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Your email address will not be published. Also, aluminum or silicon may be added to remove oxygen. 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.
An annulus is formed between the copper argon-oxygem stainless tubes.
During the final stage of blowing, the ratio of oxygen to argon is changed to 1: Desulphurization is achieved by having a argon-oxygeh lime concentration in the slag and a low oxygen activity in the metal bath. Sulfur removal is a slag — metal reaction that occurs during the reduction phase of the process. Haynes International Case Study Video.
The bath is then stirred with inert gas, typically for around five to eight minutes. Annealing Low hydrogen Short circuit. This accretion protects the tuyere and surrounding refractory. For converters that tap into a ladle held by a crane, a sliced cone top section is often used.
Ingot (AOD Refining)
Decarburization time ranges from 20 to 35 minutes in modern converters start from 1. Praxair can review your system and design an upgrade using: The length of the blow period is determined by the starting carbon and silicon levels of the hot metal charged to the AOD converter. Special designs exist for normalizing the flow in the annular gap.
Chromium pickup from the brick is possible. The decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal argln-oxygen.
Most of the recent converter installations include the use of a top lance for blowing oxygen. There are two basic choices of refractory type, magnesite-chromite, and dolomite. The important feature of an AOD converter is that it is normally side blown. The AOD converter can be rotated downwards so that the side mounted tuyeres are above the bath level during charging of the liquid steel.
After sulphur levels have been achieved the slag decarburozation removed from the AOD vessel and the metal bath is ready for tapping. For example, with a start sulphur of 0. Tuyere size and number depend on specific process parameters.
Magnesite chromite refractories have high wear resistance but have a higher unit cost than dolomitic refractories. The process is so popular because it combines higher metallic yields with lower material costs. 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 AOD converter has tuyeres mounted in the sidewall or in the bottom.
Oxidation of carbon continues, but oxidation of chromium is limited. The intimate gas — metal contact and excellent slag — metal mixing facilitate refining reactions. At any given time, one of the converters is in the tiltable trunnion ring refining steel, a argon-oxggen newly lined converter is at a preheating station, and the third converter is at a reline station. Decarburizarion the AOD vessel isn’t externally heated, the decarburizagion stages are also used for temperature control. Praxair can quote a server-only option for these systems.
Argon oxygen decarburization – Wikipedia
The process is very popular because it combines higher metallic yields with lower material costs. Bessemer process Open hearth furnace Electric arc furnace Basic oxygen process. AOD converter decarburization refractories Side blown stainless steel. Other trimming alloy additions might be added at the end of the step. Dolomitic refractories are usually less costly than magnesite chromite refractories and chromium pickup is not a factor.