Deep Steel Desulfurization Practice

Abstract

This article is aimed to study theoretical knowledges related to deep steel desulfurization and their practical application in specific production conditions. The main goal of this study was to verify the efficiency of added CaSi to processed heats in two batches, i.e., first for deep desulfurization at the beginning of the secondary metallurgy and then in a second smaller batch at the end of that process for final modification. At the beginning of the secondary metallurgy process, it was crucial to prepare a suitable chemical composition of ladle slag with advantageous properties for good assimilation of sulfur-based inclusions from desulfurization reactions. Samples were taken of final basic oxygen furnace slag, ladle slag before the deep desulfurization process at the beginning of secondary metallurgy and ladle slag at the end of processing. Detailed cleanliness analyses of steel samples taken from mold during the casting were performed using the Automated Steel Cleanliness Analyses Tool. For better understanding and interpretation of the obtained cleanliness results and their relationship, the following defined parameters were used: ratio of “Ca/Al” oxide inclusions, percentage of “liquid” inclusions and area of CaS inclusions.