METHOD FOR BLOWING TOP-BOTTOM COMBINED BLOWING CONVERTER

摘要

PURPOSE: To improve the reduction of cost and the hitting ratio of P concn. in molten steel at the time of stopping the blowing by deciding the timing for increasing stirring at the end stage of blowing in a top-bottom combined blowing converter based on the P concn. in the molten iron as the main raw material or calculated slag quantity. ;CONSTITUTION: In the blowing method in the top-bottom combined blowing converter executing the reifing by using a top blowing lance and a bottom blowing tuyere, by changing over the bottom blowing gas from pure oxygen into inert gas or mixed gas of the pure oxygen and the inert gas, the stirring of the molten steel is increased. This changing-over timing is decided by obtaining the necessary molten steel stirring intensity in the end stage of blowing from the P concn. in the molten iron as the main raw material or the slag quantity decided from the aimed P concn. at the time of stopping the blowing. Further, this increase of stirring is desirable to be executed after decarburizing to ≤0.3wt.% C concn. in the molten steel. By this method, the saving of the inert gas consumption or the shortening effect of the blowing time is obtd.;COPYRIGHT: (C)1994,JPO&Japio