METHOD FOR OPERATING BLAST FURNACE

PROBLEM TO BE SOLVED: To provide a method for operating a blast furnace, in which the combustibility is secured to perform stable blast furnace operation while decreasing the pressure-loss in a tuyere in the blast furnace operation blowing gaseous reducing material and the blowing quantity of the gaseous reducing material is increased to attain an decrease in the reducing material ratio. SOLUTION: The method for operating the blast furnace, in which a multi-tube structural lance 1 having at least double-tube structure is used, and the gaseous reducing material 3 is blown in the furnace from the innermost tube 2 in the lance 1, and the gaseous material 5 having no combustion-supporting property, is blown into the furnace from the tube 4 at the outside of the innermost tube, is used. It is desirable that as the gaseous reducing material 3, the reducing gas containing at least one kind or more selected from methane, propane, hydrogen and CO, is blown, and as the gaseous material 5 having no combustion supporting property, this gas containing at least one kind or more selected from inert gas, vapor and carbon dioxide gas, is blown under condition of a linear flowing speed v2 having ≥1.5 times of the lance tip end linear flowing speed v1 for gaseous reducing material. COPYRIGHT: (C)2010,JPO&INPIT