Abstract: In order to investigate the feasibility of converter blown small particle limestone for steel making, based on the basic experiment of slag dephosphorization, the effect of small particle limestone and lime for slagging and dephosphorization under the same conditions was compared, and in-depth analysis was conducted from the mechanism of slag dephosphorization.The study shows that the small particle limestone decomposes in the molten pool to form highly active lime, which can simultaneously achieve dephosphorization reaction inside and at the interface of the molten pool. The dephosphorization effect is equivalent to that of lime, and the dephosphorization rate of the endpoint molten iron can reach over 85 %. Small particle limestone has a faster rate of pre-phosphorus removal than lime, and can remove most of the phosphorus elements in a shorter time. Both small particle limestone and lime can achieve uniform slagging, limestone slagging slag layer is higher, foam slag is more obvious. The distribution of elements in slag is uniform, and phosphorus elements are mainly enriched in Ca₃(PO₄)₂ solid solution phase.

Key words: converter steelmaking, small particle limestone, lime, dephosphorization, foamed slag