Estimation of Oxygen and Nitrogen Absorption of Molten Steel during Tapping from Converter

Abstract

The amounts of nitrogen and oxygen absorbed during tapping from the converter are estimated. The mass transfer coefficient in the liquid phase during tapping becomes large as 0.1.0.2 cm/s, due to the violent agitation of molten steel in the ladle. Absorption efficiencies of nitrogen by air entrainment, ηE, and through the surface of tapping stream, η_st, decrease with increasing oxygen content in the molten steel. Although the amounts of nitrogen and oxygen absorbed during tapping are practically independent of the tilting rate, the heat size, and the profile of the converter, they decrease with decreasing tapping height and somewhat increase with increasing slag depth in the converter. It is also estimated that those amounts increase with decreasing tapping hole diameter and with increasing its length.
A nomograph for the estimations of oxygen and nitrogen absorptions by the gas entrainment and also through the surface of tapping stream was proposed. The estimated amounts of nitrogen absorbed during tapping agreed well with the values reported in the literature.