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This work has aimed at evaluating the deoxidation characteristics for Si-Mn in Electric Arc Furnace (EAF) melt shops. A statistical methodology led to the identification of the key EAF tapping process parameters that affect Si and O evolution during secondary refining. A first order kinetic equation estimated the deoxidation constants at the beginning of the ladle furnace process. The experimental values were5,3·10-3 s-1 and 3,6·10-3 s-1 As expected, these values are higher than that estimated for the reduction of the total oxygen content based on the gas injection agitation energy, which was 1,67·10-3 s-1, confirming the importance of the agitation caused by tapping. A model that couples slag and metal composition evolution in special from tapping to arrival at the ladle furnace (LF) was developed. The model confirmed the presence of undissolved slag solid fraction on arrival at the LF and made reasonable prediction for the liquid phase composition. The potential, limitations and applicability of each model are discussed, aiming at defining the next steps for a complete model for ferro-alloys additions to Si-Mn steels. [ABSTRACT FROM AUTHOR]

This paper presents the results of the application of the post-stirring technique in the BOF of Usiminas, in Ipatinga. The tests consisted basically in the rinsing of the metal bath with argon injection after finished the oxygen blowing, through tuyeres placed in the bottom of the converters, for a pre-established period. The results showed that the post-stirring technique allowed a mean reduction of 250 ppm in the oxygen content and 30 ppm in the phosphorus content of the steel. It is possible to conclude that post-stirring technique is effective in the process optimization. Besides reducing the phosphorus content in the steel, it is verified a huge opportunity to reduce the consumption of deoxidizing materials, due to a decrease in the oxygen level, reducing costs and improving the steel cleanness. [ABSTRACT FROM AUTHOR]