Effect of Slag Composition on the Desulfurization and Dephosphorization of Molten Steel

Abstract

In order to produce steels with ultra low sulfur and phosphorus, some experiments were done to clarify the influence of slag composition on the desulfurization and dephosphorization rates. The results obtained were summarized as follows:
(1) Large rate constants for desulfurization and dephosphorization were obtained by using slags which contained Na₂O, B₂O₃, Na₂B₄O₇ or K₂O in CaO-CaF₂ base and had great reaction ability as well as fluidity.
(2) Simultaneous reaction of desulfurization and dephosphorization became possible for steels containing some oxygen, with the use of these slags.
(3) Because of the strong erosive effect of these slags, refractories should be selected according to the slag composition.