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

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Ville-Valtteri Visuri
  • Mika Järvinen

  • Aki Kärnä
  • Petri Sulasalmi
  • Eetu-Pekka Heikkinen
  • Pentti Kupari
  • Timo Fabritius

Research units

  • University of Oulu
  • Outokumpu Stainless Oy

Abstract

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 metal bath. This paper presents validation and preliminary results with twelve industrial heats. In the studied heats, the last combined-blowing 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 to 0.5 wt pct before the studied stage to 0.1 to 0.2 wt pct after the studied stage. The results suggest that the model is capable of predicting changes in metal 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 top-blowing 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.

Details

Original languageEnglish
Pages (from-to)1868-1884
Number of pages17
JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
Volume48
Issue number3
Publication statusPublished - 1 Jun 2017
MoE publication typeA1 Journal article-refereed

ID: 14302299