A mathematical model for reactions during top-blowing in the AOD process : validation and results
|Author:||Visuri, Ville-Valtteri1; Järvinen, Mika2; Kärnä, Aki1;|
1Process Metallurgy Research Unit, University of Oulu, PO Box 4300, 90014 University of Oulu, Finland
2Department of Mechanical Engineering, Aalto University, PO Box 14440, 00076 Aalto, Finland
3Outokumpu Stainless Oy, 95490 Torne, Finland
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe201704246241
|Publish Date:|| 2018-03-27
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 Mode,” 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 tuye’res 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.
Metallurgical and materials transactions. B, Process metallurgy and materials processing science
|Pages:||1868 - 1884|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
215 Chemical engineering
Outokumpu Stainless Oy, the Finnish Funding Agency for Technology and Innovation (TEKES), the Graduate School in Chemical Engineering (GSCE), the Academy of Finland (Projects 258,319 and 26,495), the Finnish Foundation for Technology Promotion, the Finnish Science Foundation for Economics and Technology, and the Tauno Tönning Foundation are gratefully acknowledged for funding this work.
© The Minerals, Metals & Materials Society and ASM International 2017. Published in this repository with the kind permission of the publisher.