Influence of ladle slag additions on BOF process performance

Abstract

A plant trial has been performed, with recycling of ladle slag to the LD converter at SSAB EMEA, Luleå, Sweden. The effect of ladle slag addition on the slag and steel composition, together with the slag weight, was investigated with sampling both during the blow and at blow end. The addition of ladle slag resulted in an increase in slag weight between 1 and 2 t throughout the blow and an increase of 3 wt-% in the slag Al₂O₃ content. This indicated that the ladle slag melted during the initial stages of the blow and enhanced the early slag formation. Lime additions were reduced with 3·5 kg t⁻¹ liquid steel without drawbacks on the phosphorus or sulphur refining. Heats with added ladle slag had an increase in blowing time with ∼4% and an increased tendency for slopping. However, this can be handled by different lance and addition programmes.