PURPOSE: To reduce unit consumption of carbonic material and production cost by additionally charging raw iron ore corresponding to excess carbonic material in pre- reduced raw material into a smelting reduction furnace at the time of producing molten iron by charging into the smelting reduction furnace after pre-reducing the iron ore by charging the mixed raw material of the iron ore, carbonic material and slag making agent into a pre-reduction furnace.

CONSTITUTION: The mixed raw material of the iron ore, carbonic material and slag making agent is charged into the pre-reduction furnace 2, to execute pre-solid phase reduction to Fe2O3 in the iron ore. In this case, the excess carbonic material in the mixed raw material is blended to more than the necessary quantity to reduction in order to prevent sticking of the raw material. The raw iron quantity corresponding to the excess carbonic material in the pre-reduced raw material discharged from the pre-reduction furnace 2 is added and charged into the smelting reduction furnace 4. As the other method, the excess carbon material in the raw material discharged from the pre-reduction furnace 2 is sorted, removed and returned to the pre-reduction furnace 2 and the pre-reduced raw material containing no excess carbonic material is charged into the smelting reduction furnace 4. As the excess carbonic material is effectively utilized, the unit consumption of the carbonic material in this production line can be reduced and the production cost is reduced.