転炉Fe_tOダイナミック制御による高効率転炉溶銑脱りん技術

摘要

製鋼工程におけるスラグ発生量低減，鋼材の品質向上を目的に溶銑脱りん処理が行われる。本開発では，小型溶解炉実験，実機転炉型溶銑脱りん処理において，上吹き酸素により生成するFe_tO生成挙動と，脱りん反応に及ばすスラグ中Fe_tO濃度の影響を調査し，反応モデルに基づく解析を行った。その結果，スラグ中Fe_tO濃度が脱りん反応効率に大きく影響を及ぼすこヒが明らかとなり，得られた結果に基づき，安定的な低りん銑化を目的に，吹鍊中の酸素バランスに基づくスラグ中Fe_tO濃度の推定，独立成分分析による上吹き酸素のパターン決定を行う制御系を確立した。その結果，安定した低りん銑化が可能ビなり，低P鋼種([mass%P](≤)0.015)の安定製造に貢献した。%Hot metal dephosphorization is frequently performed in steelmaking process to reduce slag generation and improve the quality of steel products. In this report, iron oxide generation and dephosphorization behavior in laboratory-scale experiments and an actual converter were investigated and analyzed by mathematical models. The results revealed that dephosphorization is significantly influenced by iron oxide in slag. Based on these results, a new control system was introduced, which comprises 1) estimation and dynamic control of iron oxide in slag by calculating the oxygen balance at 1 second interval during blowing and 2) guidance on top blowing patterns by applying independent component analysis. As a result, phosphorus content after blowing decreased and also became stable, which contributed to production of low-phosphorus steel grades ([mass%P] (≤) 0.015).