METHOD OF DESULFURIZING ULTRA LOW SULFUR STEEL

• Main Authors: KOH, JAE KYUN, LEE, DUK HWAN, KOO, HONG MO, JUNG, SOON JONG
• Format: Patent
• Language: English; Korean
• Published: 15.05.2017
• Subjects: CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

The present invention relates to a method of desulfurizing ultra-low sulfur steel capable of improving quality and productivity. According to an embodiment of the present invention the method of desulfurizing ultra-low sulfur steel comprises: a primary desulfurization step of inputting, at the time of discharging molten metal to a ladle in a revolving furnace or an electric furnace, molten steel desulfurizing agent including quicklime (CaO) by 5-7 kg/molten metal-ton (t) and a slag deoxidizer including aluminum (Al) by 1/3 or less with respect to a total weight of the molten metal desulfurizing agent to perform bubbling; a step of analyzing components of the primarily desulfurized molten metal; and a secondary desulfurization step of calculating a difference between a content of sulfur (S) of the molten metal in the ladle and the target content of sulfur (S) of molten metal, re-inputting the slag desulfurizing agent of 60-100 kg per 10 ppm of the content of sulfur (S), and re-inputting the molten metal desulfurizing agent to the molten metal such that the total amount of the molten metal desulfurizing agent input to the molten metal is 2.8 to 3.5 times with respect to the total amount of the slag desulfurizing agent input to the molten metal, to perform bubbling. 극저류강의 탈황 방법이 개시된다. 본 발명의 일 실시예에 따른 극저류강의 탈황 방법에 따르면, 용강을 전로 또는 전기로에서 레이들로 출강시, 생석회(CaO)를 포함하는 용강 탈황제를 5 내지 7Kg/용강-톤(t) 및 알루미늄(Al)을 포함하는 슬래그 탈산제를 상기 용강 탈황제 전체 중량에 대하여 1/3이하로 투입하여 버블링(bubbling)하는 1차 탈황 단계, 1차 탈황된 상기 용강의 성분을 분석하는 단계 및 상기 레이들 내 상기 용강의 황(S) 함량과 목표 용강의 황(S) 함량 사이의 차이를 산정하여, 황(S) 함량 10ppm당 60 내지 100Kg의 상기 슬래그 탈산제를 재투입하고, 상기 용강에 투입된 상기 슬래그 탈산제의 총량에 대하여 상기 용강에 투입된 상기 용강 탈황제의 총량이 2.8 내지 3.5배가 되도록 상기 용강에 상기 용강 탈황제를 재투입하여 버블링하는 2차 탈황 단계를 포함한다.