STEEL MAKING METHOD USING AUXILIARY LANCE

摘要

PURPOSE:To improve the thermal efficiency of a refining operation in a converter in the stage of refining a molten iron to a steel in an oxygen top blown converter by using auxiliary lances in addition to a main lance and burning effectively the CO in forming slag. CONSTITUTION:A molten iron 3 subjected preliminarily to desiliconization, desulfurization and dephosphorization treatments is charged into an oxygen top blown converter 1 having gas blowing tuyeres 7 in the bottom and gaseous oxygen is blown through a main top blowing lance 4 to the molten metal surface to oxidize the C contained therein thereby decarburizing and refining the molten iron and producing a molten steel. Oxygen is fed in such a way that the molten metal surface is recessed to 80-400mm. depth by the oxygen blown through the main lance 4 in this case and gaseous oxygen is blown through plural auxiliary lances 8 provided around the lance 4 at <=60% of the amt. of the oxygen from the lance 4. The CO in the forming slag 5 is thoroughly burned by such gaseous oxygen and the heat of the combustion is transmitted to the molten metal 3 stirred by the gas from the tuyeres 7. The oxygen efficiency is improved by the top blown converter at the decreased amt. of oxygen and the compounding rate of scrap is improved.