PURPOSE: To adequately control the temp. in a blast furnace in the dislodged stage of the deposits on the inside wall of a blast furnace by detecting the dislodgment of said deposits in an early time from the difference in the furnace wall temp. before and after the dislodgment and adjusting a coke ratio according to the carbon solution reacting weight obtd. from the change of the furnace top gas components in this stage.

CONSTITUTION: The deposits formed by the charging raw material on the inside wall of the blast furnace during the operation of said furnace are dislodged therefrom as such deposits hinder the descending of the raw material and spoil the stabilization of the operation. The temp. in the furnace in said part is quickly increased to hinder the furnace condition by such dislodgment and therefore, the dislodgment of the deposits is detected by an abrupt change (elevation) of the furnace wall temp. and the operation is continued as it is or the operation change such as charging of blank or decreased charging is executed according to the fluctuation of the deposit dislodgment index by the specific equation to indicate the size of the dislodged matter. The coke ratio of the charging raw material is at the same time adjusted according to the change of the carbon solution reacting weight in the furnace calculated from the change rate of the furnace top gas components, by which the temp. in the furnace is adequately controlled and the blast furnace condition is stabilized.