METHOD FOR PRETREATING MOLTEN IRON

PURPOSE:To efficiently execute desulfurization and dephosphorization pre- treatment in a converter by adding flux after receiving a molten iron in the top-bottom combined blowing converter and executing the desulfurization and dephosphorization pre-treatment while controlling the specific quantities of top blowing O2 and bottom blowing inert gas. CONSTITUTION:The converter for the pre-treating method is used as the top- bottom combined blowing converter and the flux is added, and the high pressure oxygen is blown against the molten steel with the lance from the upper part of the molten iron surface by 1.0-1.4Nm /t oxygen quantity, and on the other hand, the inert gas of N2, etc., is supplied from the tuyere at the furnace bottom of the top-bottom combined blowing converter by 0.08-0.15Nm /t. Therefore, on the upper face of the molten steel, by vigorous stirring of the molten steel generated by the high pressure oxygen supplied from a lance, rapid gas-molten steel reaction is induced and also slagging of the flux is accelerated, and the dephosphorization reaction between the slag and the molten steel is accelerated.