BLOWING METHOD FOR TOP AND BOTTOM BLOWN CONVERTER

摘要

PURPOSE:To realize adequate dephosphorization as well under the improvement in the yield of Mn and Fe by mixing an inert gas with bottom blowing gaseous O2 in the stage when a molten iron contg. P at a prescribed rate or above is decarburized to a prescribed value or below by top and bottom blowing of gaseous O2. CONSTITUTION:The concn. of C is decarburized to <=0.3wt% by top and bottom blowing of gaseous O2 in the stage of subjecting a molten iron contg. >=0.03wt% P to blowing. An inert gas such as Ar, N2 or the like is mixed with the bottom blowing gaseous O2 so as to be incorporated therein at 10-90vol% of the amt. of the bottom blowing gas in this stage. The decarburization reaction is thus accelerated by the stirring effect of the gaseous CO owing to the decrease in the partial pressure of CO in the foam of the bottom blowing gas and the inert gas itself. The blowing is executed to stopping of blast while the oxidation degree of the slag in which the T.Fe in the slag formed by the above-described blowing occupies 10-20wt% is assured. As a result, the decarburization reaction which decreases upon attainment of the pure oxygen blowing period by the top and bottom blown converter is reactivated advantageously by mixing the inert gas with the bottom blowing gaseous O2.