Desulfurizing agent for molten steel and desulfurization method using the same

摘要

PROBLEM TO BE SOLVED: To provide a desulfurizing agent and a desulfurization method capable of manufacturing an extra-low S steel having S10 ppm or less stably and in short time without using CaFin a desulfurization treatment of a molten steel after converter refining.SOLUTION: A desulfurizing agent for a molten steel has a component composition containing, by mass%, CaO:66% or more, AlO:2 to 22%, SiO:2 to 10%, MgO:0 to 10%, X:0.5 to 5%, (AlO+SiO)/(CaO+X):0.03 to 0.32, where X is any one or more kind of NaO, KO, LiO) and a desulfurization method includes discharging CaO into a ladle when the molten steel is tapped from a converter to the ladle, discharging an Al source having bulk specific gravity of 0.1 to 2.7 on a slug in the ladle during or after tapping, or at both timings, then blowing the desulfurizing agent into the molten steel.