PURPOSE: To improve the presuming accuracy of temps. in each steel making process and to reduce the energy consumption, etc., by introducing measuring temp. for ladle refractory to the process just before blowing calculation and quantifying effect on the molten steel temp. caused by heating condition of ladle.

CONSTITUTION: Natural cooling condition for the inner wall of the ladle is measured by using a temp. sensor, such as radiation thermometer, etc., in the process before receiving molten metal. And, the temps. at any two times are accurately measured and based on these measured values, the inner wall temp. Ttap after any time (tap starting time) and temp. TH at the time corresponding to heat content appears to the inner wall temp., are calculated. Nest, according to the schedule after tapping, temp. drop rate for the molten steel in each time section during transportation, secondary refining and tundish pouring is obtained from presuming temp. TH and natural cooling times. Further, according to tapping schedule, the drop rate for the molten steel caused by radiated heat to the ladle, etc., at the time of steel tapping, is found from the presuming temp. Ttap. As adding temp. changing degrees by charging material at the time of steel tapping and during the secondary refining to the both temp. drops of molten steel, the steel tapping target temp. is set.