A Mathematical Model for the Reduction Stage of the AOD Process. Part II: Model Validation and Results

Visuri, Ville‐Valtteri; Järvinen, Mika; Savolainen, Jari; Sulasalmi, Petri; Heikkinen, Eetu‐Pekka; Fabritius, Timo

doi:10.2355/isijinternational.53.613

Cited by 19 publications

(11 citation statements)

References 29 publications

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“…Similarly to our earlier work, [19][20][21] the melting times of materials with a melting point lower than that of the steel bath were determined based on the melting time of spherical particles. More specifically, the melting times of additions were calculated according to…”

Section: 2 Description Of Materials Additionsmentioning

confidence: 99%

A Mathematical Model for Reactions During Top-Blowing in the AOD Process: Validation and Results

Visuri

Järvinen

Kärnä

et al. 2017

Metall Mater Trans B

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In earlier work, a fundamental mathematical model was proposed for side-blowing operation in the argon-oxygen decarburization (AOD) process. In the preceding part "Derivation of the Model", a new mathematical model was proposed for reactions during top-blowing in the AOD process. In this model it was assumed that reactions occur simultaneously at the surface of the cavity caused by the gas jet and at the surface of the metal droplets ejected from the steel bath. This paper presents validation and preliminary results with twelve industrial heats. In the studied heats, the last combinedblowing stage was altered so that oxygen was introduced from the top lance only. Four heats were conducted using an oxygen-nitrogen mixture (1:1), while eight heats were conducted with pure oxygen. Simultaneously, nitrogen or argon gas was blown via tuyères in order to provide mixing that is comparable to regular practice. The measured carbon content varied from 0.4-0.5 wt-% before the studied stage to 0.1-0.2 wt-% after the studied stage. The results suggest that the model is capable of predicting changes in steel bath composition and temperature with a reasonably high degree of accuracy. The calculations indicate that the top slag may supply oxygen for decarburization during top-blowing. Furthermore, it is postulated that the metal droplets generated by the shear stress of topblowing create a large mass exchange area, which plays an important role in enabling the high decarburization rates observed during top-blowing in the AOD process. The overall rate of decarburization attributable to top-blowing in the last combined-blowing stage was found to be limited by the mass transfer of dissolved carbon.

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Section: 2 Description Of Materials Additionsmentioning

confidence: 99%

A Mathematical Model for Reactions During Top-Blowing in the AOD Process: Validation and Results

Visuri

Järvinen

Kärnä

et al. 2017

Metall Mater Trans B

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“…By including mass transfer reversible reactions and various additions to mass and heat balance, the model was able to predict the reduction stage in the AOD reasonably well. [16] Another method for existing kinetic process model predictions is the effective equilibrium reaction zone (EERZ) [17][18][19][20] coupled with thermodynamic software such as FactSage or Thermo-Calc. With the help of thermodynamic databases, the local equilibrium calculation approach is applicable and the change of the chemical composition of bulk is controlled by interface reactions and the mass transfer coefficient.…”

Section: Introductionmentioning

confidence: 99%

A Fundamental Investigation of Decarburization Reactions in the Argon–Oxygen Decarburization Converter Using Coupled Computational Fluid Dynamics and Thermodynamics Databases

Chanouian

Ahlin

Tilliander

et al. 2022

steel research int.

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Metallurgical converters such as the argon–oxygen decarburization (AOD) converter generally utilize gas blowing for the mixing and refinement of liquid steel. Due to the harsh environment of the complex and opaque system, it is common practice to study the stirring of the process through physical and numerical models. Effective mixing in the bath has an important role in refinement such as decarburization and has been vividly studied before. However, high‐temperature chemical reactions that also play a major role are sparsely investigated. With the help of modeling, a computational fluid dynamics model coupled with chemical reactions is developed, allowing the study of both dynamic fluid transport and chemical reactions. Herein, the chemical reactions for a single gas bubble in the AOD are investigated. The study shows that a 60 mm oxygen gas bubble rapidly reacts with the melt and is saturated with carbon in 0.2–0.25 s at low‐pressure levels. The saturation time is affected by the pressure and the composition of the injected gas bubble. The impact of ferrostatic pressure on the reactions is more significant at larger depth differences.

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“…Chromium recovery is possible inside AOD converter during reduction stage when only inert gas is purged. Visuri et al have modeled mathematically for the reduction stage of the AOD process, according to them the reduction rate of chromium oxides is controlled initially by mass transfer of silicon onto the reaction surface and later by the diffusive mass transfer of chromium oxides in the slag droplets …”

Section: Introductionmentioning

confidence: 99%

“…Visuri et al have modeled mathematically for the reduction stage of the AOD process, according to them the reduction rate of chromium oxides is controlled initially by mass transfer of silicon onto the reaction surface and later by the diffusive mass transfer of chromium oxides in the slag droplets. [4,5] Nitrogen in steel melt is increased to the range of 1000-1500 ppm during nitrogen injection period as stainless steel has high equilibrium nitrogen concentration. Nitrogen can be used as substitute to nickel as nickel is costlier than nitrogen so using nitrogen reduces the production cost and sometime enhances toughness.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Nitrogen Content of Steel Melt during Stainless Steel Making Using AOD Converter

Patra¹,

Nayak

Singhal³

et al. 2016

steel research int.

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A mathematical model has been developed to predict nitrogen content in steel melt with respect to blowing time for making different grades (e.g., 304L, 204Cu, and 18Cr–18Mn–0.5N) of stainless steel using AOD converter. Firstly, bath composition and temperature are calculated based on thermodynamic modeling of refining reactions. Then bath nitrogen content is predicted considering the influence of the bath temperature and composition variation as well as the kinetics of nitrogen absorption and desorption of steel melt. Flux and alloy additions are also taken in account for developing this model. For the purpose of development and validation of the mathematical model for predicting nitrogen content of molten steel, the required plant data is obtained from stainless steel making process performed in a 50 ton AOD converter which is equipped with a top lance and five sidewall nozzles at Jindal Stainless Ltd., Hisar in India. This mathematical model will be effective and beneficial because nitrogen prediction by this model corresponds well with actual measured values collected from steel plant. This numerical model will also help in achieving optimum as well as effective use of argon gas and critical control over final nitrogen content in stainless steels.

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A Mathematical Model for the Reduction Stage of the AOD Process. Part II: Model Validation and Results

Cited by 19 publications

References 29 publications

A Mathematical Model for Reactions During Top-Blowing in the AOD Process: Validation and Results

A Mathematical Model for Reactions During Top-Blowing in the AOD Process: Validation and Results

A Fundamental Investigation of Decarburization Reactions in the Argon–Oxygen Decarburization Converter Using Coupled Computational Fluid Dynamics and Thermodynamics Databases

Prediction of Nitrogen Content of Steel Melt during Stainless Steel Making Using AOD Converter

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