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Physical Modelling of the Effect of Slag and Top-Blowing on Mixing in the AOD Process

  • Tim Haas
  • Ville-Valtteri Visuri
  • Aki Kärnä
  • Erik Isohookana
  • Petri Sulasalmi
  • Rauf Hürman Eriç
  • Herbert Pfeifer
  • Timo Fabritius
Conference paper

Abstract

The argon-oxygen decarburization (AOD) process is the most common process for refining stainless steel. High blowing rates and the resulting efficient mixing of the steel bath are characteristic of the AOD process. In this work, a 1:9-scale physical model was used to study mixing in a 150 t AOD vessel. Water, air and rapeseed oil were used to represent steel, argon and slag, respectively, while the dynamic similarity with the actual converter was maintained using the modified Froude number and the momentum number. Employing sulfuric acid as a tracer, the mixing times were determined on the basis of pH measurements according to the 97.5% criterion. The gas blowing rate and slag-steel volume ratio were varied in order to study their effect on the mixing time. The effect of top-blowing was also investigated. The results suggest that mixing time decreases as the modified Froude number of the tuyères increases and that the presence of a slag layer increases the mixing time. Furthermore, top-blowing was found to increase the mixing time both with and without the slag layer.

Keywords

AOD mixing time slag top-blowing 

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Copyright information

© TMS (The Minerals, Metals & Materials Society) 2016

Authors and Affiliations

  • Tim Haas
    • 1
    • 2
  • Ville-Valtteri Visuri
    • 1
  • Aki Kärnä
    • 1
  • Erik Isohookana
    • 1
  • Petri Sulasalmi
    • 1
  • Rauf Hürman Eriç
    • 3
  • Herbert Pfeifer
    • 2
  • Timo Fabritius
    • 1
  1. 1.Process Metallurgy GroupUniversity of OuluUniversity of OuluFinland
  2. 2.Department of Industrial Furnaces and Heat EngineeringRWTH Aachen UniversityAachenGermany
  3. 3.Department of Materials Science and EngineeringAalto UniversityAaltoFinland

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