METHOD FOR REFINING CONVERTER TYPE MOLTEN PIG IRON DEPHOSPHORIZATION FURNACE

摘要

PROBLEM TO BE SOLVED: To execute a molten pig iron dephosphorization treatment with a little quicklime unit requirement and without using halide. SOLUTION: In the method for executing the molten pig iron dephosphrization treatment by the quicklime and oxygen and/or iron oxide in a top and bottom blown converter, a stage of tapping the molten pig iron while allowing dephosphorization slag to remain wholly or partly in the furnace after the end of the dephosphorization treatment, then charging the molten pig iron of the next charge into the furnace in the state of allowing the dephosphorization slag to remain and subjecting the molten pig iron to the dephosphorization is executed at least >=1 times. The slag basicity at the end of the dephosphorization treatment is preferably regulated to 1.5 to 3 and the [Si] concentration in the molten pig iron to be charged to <=0.3%. The stages described above may be repetitively executed in a range where the (P) concentration in the slag amount after the dephosphorization refining is <=35%.