METHOD FOR REFINING MOLTEN STEEL

• Main Authors: NAITO KENICHIRO, KITAMURA SHINYA
• Format: Patent
• Language: English
• Published: 17.02.1998
• Edition: 6
• Subjects: CHEMISTRY; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

PROBLEM TO BE SOLVED: To promote decarburizing reaction and to shorten degassing treating time by blowing hydrocarbon base gas into molten steel in a vacuum vessel and forcedly and positively cooling a local position of the molten steel, at the time of executing the vacuum treatment of the molten steel by an RH method or a DH method. SOLUTION: The molten steel 2 in the vessel 1 is locally cooled by blowing the hydrocarbon base gas as the cooling gas from tuyeres 5 arranged at 50-300mm lower part from the molten steel surface position of side wall of the vacuum vessel 1 during executing the vacuum treatment. By this method, since an equilibrium constant K=Pco /(ac .ao ) of C+O=CO reaction becomes large at the local position of the cooled molten steel 2, the decarburization can be promoted. Wherein, Pco is the partial pressure of CO gas and ac and ao are the partial pressures of C and O, respectively. Then, since a solidified block 6 is formed around the tuyere 5 during gas blowing with the cooling action of the gas, the tuyere 5 is not eroded. Further, the gas blowing can be executed by using a lance instead of the blowing through the tuyere depending on the case.