CAS-OB
The CAS-OB
(Composition
Adjustment by Sealed argon bubbling Oxygen Blowing) is
a unit process designed for
controlling the steel composition and temperature in secondary
metallurgy. The process can be divided into heat-up, alloying and
reduction of slag. The objective of the heat-up stage is to increase
the temperature of the steel bath by chemical heating with aluminium
particles. Typically, heating rates up to 10 C/min can be obtained in
industrial practice. The reduction stage aims to improve the yield of
the alloying elements.
Highlights
- The
detachment of slag droplets in ladle metallurgy was studied using CFD
simulations. The
magnitude of the interfacial area was tracked using the volume of fluid
(VOD) method. The volume of the droplets generated was found to be in
close agreement with that calculated analytically on the basis of
energy balance at the interface. Furthermore, it was found
that the size distribution of slag droplets
can be characterised well with the Rosin-Rammler-Sperling distribution
function.
- Two
mathematical models were derived and validated for chemical reactions
during the heat-up and reduction stages. The employed approach is somewhat similar as in
the AOD models developed in our earlier work. The developed models can
be used for accurate prediction of the changes in bath composition and
temperature and are ideal tools for studying the energy efficiency and
yield of the process.
Selected publications
- A. Kärnä, M. Järvinen, P. Sulasalmi, V.-V. Visuri, and T. Fabritius, "An Improved Model for the Heat-up Stage of the CAS-OB Process: Development and Validation", Steel Research International, vol. 89, no. 10, article 1800141, 2018.
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- P. Sulasalmi, V.-V. Visuri, A. Kärnä, M. Järvinen, S. Ollila, and T. Fabritius, "A Mathematical Model for the Reduction Stage of the CAS-OB Process", Metallurgical and Materials Transactions B, vol. 47, no. 6, pp. 3544–3556, 2016.
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- P. Sulasalmi, V.-V. Visuri, A. Kärnä, and T. Fabritius, "Simulation of the effect of steel flow velocity on slag droplet distribution and interfacial area between steel and slag", Steel Research International, vol. 86, no. 3, pp. 212–222, 2015.
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- V.-V. Visuri, M. Järvinen, K. Pääskylä, A. Kärnä, P. Sulasalmi, C. D. Blasio, S. Ollila, and T. Fabritius, “Preliminary Validation of a Numerical Model for the CAS-OB Process,” Proceedings of the 7th European Oxygen Steelmaking Conference, Czech Metallurgical Society, Třinec, Czech Republic, 2014.
- M. Järvinen, A. Kärnä, V.-V. Visuri, P. Sulasalmi, E.-P. Heikkinen, K. Pääskylä, C. De Blasio, S. Ollila, and T. Fabritius, "A Novel Approach for Numerical Modeling of the CAS-OB Process: Process Model for the Heat-Up Stage", ISIJ International, vol. 54, no. 10, pp. 2263–2272, 2014.
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