JPS57131310A - Method for controlling content of phosphorus of molten steel - Google Patents

Abstract

PURPOSE:To control the end point amt. of phosphorus with high accuracy by determining the mathematical expression corresponding the rate of de-P and the amts. of P and C in steel and measuring the amt. of P, C in the steel at the end period of blowing and molten metal temp. with a sublance. CONSTITUTION:The rate of de-P at the end period of blowing of converter operations is expressed by the mathematical expression wherein the amts of P, C of molten steel (hereinafter omitted) are used as variables. In accordance with the actual data including at least this expression and the amts. of P, C obtained through measurement with a sublance at the point of time before a suitable time from the end point of blowing, and further molten steel temp. and the amt. of a flux agent added up to the end point of blowing, the relation expressing the correlations of these variables is beforehand obtained. At every blowing, the amts. of P and C obtained through the measurement with a sublance at the point of time before a suitable time from the forecast end point of blowing, molten steel temp. and the target values of these at the end point of blowing are given at least to said relation. The amt. of a flux agent to be charged into the molten steel in the period since said point of time till the end point of blowing and if necessary, the amt. of O2 for C blow-down are calculated and the operations are performed by the results thereof.