METHOD FOR MANUFACTURING STEEL USING RETURNED MOLTEN STEEL

摘要

PURPOSE: A method for manufacturing steel is provided to manufacture steel by recharging a partial or all molten steel returned after converter refined in the previous batch into a converter and refining the recharged molten steel through appropriate blowing patterns. CONSTITUTION: The method for manufacturing steel using returned molten steel comprises the steps of charging the deoxidized molten steel into a converter by deoxidizing dissolved oxygen in molten steel returned after refining in the previous batch to 20 ppm or less; performing blowing by adjusting an oxygen lance to an elevation that is the same as that of the oxygen lance during end blowing performed when refining in the previous batch, or an elevation elevated within the range of at least 12% or less, and blowing air with an oxygen blowing flow rate which is 10 to 35% lower than a flow rate of end blowing performed when refining in the previous batch into the returned molten steel charged; and injecting all of the residual sintered ore into molten steel by a 60% blowing proceeding time point after simultaneously injecting calcium oxide into molten steel right after the blowing initiation and injecting 20 to 50% of all sintered ore to be injected into molten steel.