| 摘要 |
PURPOSE: A method for controlling a density of gas in the bottom of a blast furnace is provided to stably secure high pulverized coal injection conditions by restraining a density increase of gas in the hearth bottom caused by increasing of combustion gas for pulverized coal when injecting a large amount of pulverized coal into the blast furnace. CONSTITUTION: The method for controlling a density of gas in the bottom of a blast furnace(10) comprises the processes of using a low volatile coal and supplying pure oxygen along with air in the atmosphere into the furnace at the same time, controlling a moisture content in the blowing air supplied into the furnace to +5 g/Nm2 or less, and increasing a top pressure of the furnace to about 2.8 kg/cm2 so as to lower a generation amount of combustion gas generated during the combustion of volatile matter in the furnace; and performing lap iron tapping by forming a fusing zone into a reverse "V" shape(16), lowering a soft melting temperature to less than 1450 deg.C, restraining a used amount of subsidiary raw material in the furnace to less than 2% of a used amount of iron ore, adjusting a basicity of molten slag produced in the furnace to about 1.2, and opening two tap holes at the same time so as to increase a residence space(15) of combustion gas inside the hearth bottom.
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