METHOD FOR DECARBURIZE-REFINING CHROMIUM-CONTAINING MOLTEN IRON

• Main Authors: NAITO KENICHIRO, KITAMURA SHINYA
• Format: Patent
• Language: English
• Published: 25.05.1999
• 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 provide a method for feeding oxygen which can drastically reduce the oxygen gas flowing rate while keeping the intensity of the oxygen jet and to improve yield of chromium and the reducing of consumption of inert gas, etc., at the time of decarburize-refining chromium-containing molten iron to the low carbon range by using a top-blown lance. SOLUTION: At the time of executing the decarburize-refining by blowing oxygen gas into the chromium-containing molten iron in a refining vessel from the top-blown lance, the top-blown lance having two or more systems 3a, 3b which can independently control the flowing rates or the presses of the oxygen gas and 2-10 of the total cross sectional area ratio of nozzle throat parts at the max. and the min. systems in the total cross sectional area of the nozzle throat part, is used. Then, in the range of >=1.5 wt.% [C] in the molten iron, the oxygen gas is fed from the whole systems, and in the range of <=0.7 wt.% [C], the oxygen gas is fed from the whole or a part of the systems except the max. system of the total cross sectional area of the nozzle throat part.