Method for Manufacturing Molten Steel by Converter Refining Process

摘要

PURPOSE: A method for refining molten steel in converter is provided to improve stirring power of slag by repeatedly changing flux of oxygen and melt thus remove skull stuck to oxygen blowing lance during nitrogen splash coating by dividingly injecting iron ore into converter, thereby maximizing reaction in the furnace. CONSTITUTION: In a converter refining method for manufacturing molten steel by injecting a principal raw material of hot metal, a subsidiary raw material of iron ore and coolant into converter and blowing oxygen to molten iron in the converter through lance, the method for refining molten steel in the converter comprises the steps of observing a position of the lance to which skull is adhered by observing an external appearance of the lance; controlling oxygen flux to 54,150 to 59,850 Nm¬3/hr at a time point corresponding to up to 9.5-10.5% of the total blowing time after blowing initiation, alternately maintaining the minimum oxygen flux of 38,900 to 43,000 Nm¬3/hr and the maximum oxygen flux of 57,900 to 64,000 Nm¬3/hr at time point corresponding to from 19-21% to 61-68% of the total blowing time, controlling the oxygen flux to 52,200 to 57,700 Nm¬3/hr at a time point corresponding to from 80-89% to 100% of the total blowing time, and dividingly injecting the iron ore into the converter two or more times at the time point corresponding to from 19-21% to 61-68% of the total blowing time after blowing initiation in case that the skull is adhered to an upper part of the lance; and alternately maintaining the minimum oxygen flux of 38,900 to 43,000 Nm¬3/hr and the maximum oxygen flux of 57,900 to 64,000 Nm¬3/hr at time point corresponding to from 19-21% to 61-68% of the total blowing time after blowing initiation, controlling the oxygen flux to 52,200 to 57,700 Nm¬3/hr at a time point corresponding to from 80-89% to 100% of the total blowing time, controlling height from the surface of the molten iron to the tip of the lance to 1.66 to 1.84 m at the time point corresponding to from 80-89% to 100% of the total blowing time, and dividingly injecting the iron ore into the converter two or more times at the time point corresponding to from 19-21% to 61-68% of the total blowing time after blowing initiation in case that the skull is adhered to a lower part of the lance.