Modeling the Residence Time of Metal Droplets in Slag During BOF Steelmaking

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Organisational units

External Organisational units

  • K1-MET GmbH; Stahlstraße 14; Linz, 4020, Austria
  • University of Oulu
  • K1-MET GmbH, Leoben


The ejection of metal droplets into slag due to top-blowing is characteristic of the BOF process. The residence time of the metal droplets in the slag plays a significant role in the kinetics of the metal–slag reactions. In this study, the residence time of ejected metal in slag during BOF steelmaking is investigated and various approaches, based on the blowing number theory and mass balances are compared. Previously published blowing number theories are evaluated in comparison with physically based upper and lower boundaries. The results illustrate that only some of the laboratory-scale blowing number correlations apply to industrial blowing conditions. A mathematical model is developed to predict mass fraction return rates and thus the residence time of droplets in the slag emulsion. Combined with a previously published model for ejected droplet size distribution, it is possible to predict dynamic changes in the interfacial area and mass transfer conditions for metal–slag reactions.


Original languageEnglish
Pages (from-to)1938–1953
Number of pages16
JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
Issue numberAugust
Publication statusE-pub ahead of print - 17 May 2023