DECARBURIZATION BLOWING METHOD FOR MOLTEN IRON

• Main Authors: ASAHARA AKIFUMI, SONE HIDEAKI, KANEYASU TAKAYUKI, MIYAZAKI TAKAHIRO, MARUO RYOTA
• Format: Patent
• Language: English; Japanese
• Published: 19.07.2018
• 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 decarbonizing and blowing molten iron capable of improving iron yield and promoting dephosphorization.SOLUTION: In the decarbonizing and blowing method of carbon-rich molten iron in the upper-base using an upper base-blown type converter, top-blowing oxygen speed is 1.6 to 3.6 Nm/min/molten iron mass (ton) in the final stage of decarbonizing blowing in which the carbon concentration in the molten iron becomes 0.5 mass% or less. Bottom-blowing gas flow rate (Nm/min) whose BOC value calculated by the following equation is in the range of 500 to 2000. A sum of the top-blown oxygen blowing amount and the bottom-blown oxygen blowing amount in the final stage of decarbonizing blowing is 4.0-10.0 Nm/molten iron mass (ton). BOC=Q/((W/τ)*[C]). In the equation, Qis a sum (Nm/min) of the top blown oxygen flow rate and the bottom blown oxygen flow rate, W is a mass (ton) of the molten iron, τ is the uniform mixing time (s), and [C] is the carbon concentration (mass%) in the molten iron.SELECTED DRAWING: Figure 1 【課題】鉄歩留りの向上と脱りんの推進を両立させることが可能な、溶銑の転炉脱炭吹錬方法の提供。【解決手段】上底吹き式転炉による溶銑の脱炭吹錬において、溶鉄中炭素濃度が０．５質量％以下となる脱炭吹錬末期における上吹き吹酸速度を１．６〜３．６Ｎｍ３／ｍｉｎ／溶鉄質量（ｔｏｎ）とすると共に、次式によって算出されるＢＯＣ値が５００〜２０００の範囲に収まる底吹きガス流量（Ｎｍ３／ｍｉｎ）とし、脱炭吹錬末期における上吹き吹酸量と底吹き吹酸量の和を４．０〜１０．０Ｎｍ３／溶鉄質量（ｔｏｎ）とする、上底中Ｃ濃溶洗の脱炭吹練方法。［ＱＯ２Ｓは上吹き酸素流量と底吹き酸素流量の和（Ｎｍ３／ｍｉｎ）；Ｗは溶鉄質量（ｔｏｎ）；τは均一混合時間（ｓ）；［Ｃ］は溶鉄中炭素濃度（質量％）］【選択図】図１