PRETREATMENT OF MOLTEN IRON

PROBLEM TO BE SOLVED: To provide a molten iron pretreating method for producing the molten iron in order to reduce temp. lowering at the time of pretreating the molten iron and improve thermal allowance degree at the time of blowing in a conveter. SOLUTION: At the time of executing desiliconizing treatment as the pretreatment for the molten iron, decarburizing quantity is estimated from difference between predicted oxygen quantity consumed to the oxidation of one or more elements among Si, P and Mn in the molten iron and oxygen quantity supplied into the molten iron based on an oxygen using efficiency pre-estimated from treating condition. Difference between the carbon concn. in this molten iron and a saturated carbon concn. is calculated from the calculated decarburizing quantity and the carbon concn. in the molten iron before treatment. The carbon concn. in the molten iron is made to the saturated carbon concn. or higher by supplying the carbon source containing the obtd. difference or more of the carbon concn. into the molten iron, and the carbon is added by precipitating in the produced slag and also, the oxygen is blown into the slag to burn the carbon precipitated in the slag.