DEPHOSPHORIZATION TREATMENT METHOD FOR MOLTEN IRON

• Main Authors: TODO WATARU, KAGEYAMA YUICHI, AKAI SHINICHI, NAKA MASAHIRO, NEGISHI HIDEMITSU, KAWABATA RYO
• Format: Patent
• Language: English; Japanese
• Published: 04.03.2021
• 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

To propose a preliminary treatment method of molten iron reduced in P concentration in molten iron.SOLUTION: In a method of dephosphorization-treating molten iron by blowing a refining agent (excluding a halide) containing a lime-based flux and an oxidizer into molten iron held in a refining container, a preliminary treatment method for molten iron includes adjusting a temperature at the end of treatment to 1180°C or higher and lower than 1300°C, and a basicity of slag at the end of treatment to 0.7 or more and 2.1 or less, in which the basicity of slag is a mass ratio of CaO to SiO2. The oxidizer contains CaO in a range of 10 mass% or more and 20 mass% or less and SiO2 in a range of 5 mass% or more and 10 mass% or less, and a mass ratio of CaO/SiO2 is preferably within a range of 1.2 or more and 2.2 or less.SELECTED DRAWING: Figure 1 【課題】溶銑中のＰ濃度を低減させた溶銑の予備処理方法を提案する。【解決手段】精錬容器内に保持した溶銑に石灰系フラックスおよび酸化剤を含む精錬剤（ハロゲン化物を除く）を吹き込み、溶銑を脱燐処理する方法において、処理終了時の温度を１１８０℃以上１３００℃未満の範囲とし、処理終了時のスラグの塩基度を０．７以上２．１以下の範囲に調整する、ここでスラグの塩基度とはＣａＯとＳｉＯ２との質量比である溶銑の予備処理方法である。また、酸化剤は、ＣａＯを１０質量％以上２０質量％以下の範囲で含み、ＳｉＯ２を５質量％以上１０質量％以下の範囲で含み、かつ、質量比でＣａＯ／ＳｉＯ２が１．２以上２．２以下の範囲にあることが好ましい。【選択図】図１