METHOD FOR REDUCING CONCENTRATION OF HYDROGEN IN MOLTEN STEEL BY INJECTION OF QUICKLIME BEFORE CONVERTER BLOWING AND CHANGE OF TAPPING METHOD

摘要

PURPOSE: To provide a method for changing a method for injecting quicklime into a converter before converter blowing and changing a tapping operation of the converter, thereby reducing hydrogen concentration in molten steel to prevent break out of slab during casting and directly performing casting operation after the LF process without vacuum degassing to improve quality and productivity. CONSTITUTION: In a converter capable of producing 250 to 300 tons of molten steel containing 0.07 wt.% or more of carbon per batch under a weather condition containing 50 to 80% of moisture content in the atmosphere, the method for reducing hydrogen of molten steel produced in the converter comprises a step of charging iron scrap and molten iron into the converter after tilting the converter at least twice or more by injecting quicklime into the converter before charging iron scrap and molten iron into the converter; a step of refining molten iron while blowing an amount of oxygen that is 10 to 20% more than an ordinary blowing amount of oxygen at a time point corresponding to 30 to 80% of blowing to increase decarburization rate during converter refining operation after charging of the iron scrap and molten iron; a step of injecting CaCO3 into a ladle at a time point corresponding to 1 to 5% of tapping after completing the converter refining operation while further blowing an amount of oxygen corresponding to 10 to 20% of the above oxygen amount; a step of continuously tapping molten steel in the non-deoxidized state by a time point corresponding to 70 to 80% of tapping, and injecting ferroalloy into the ladle at the time point corresponding to 70 to 80% of tapping; and a step of injecting quicklime into the ladle after completing tapping of molten steel.