Original Article

Experimental study on efficient dephosphorization behavior in electric arc furnace smelting with high scrap steel ratio

Metallurgical Technology Institute, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, PR China

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Received: 21 December 2025
Accepted: 25 February 2026

Abstract

Against the backdrop of global climate change mitigation efforts, electric arc furnace short-process steelmaking has become a core direction for the green upgrading of the steel industry due to its potential for energy conservation and emissions reduction. However, electric arc furnace steelmaking with high scrap steel ratios generally faces challenges in dephosphorization, attributable to the inherent characteristics of raw materials, process parameters, and equipment design. This poses a conflict with the low phosphorus content requirements for high-quality steel, thus hindering the development of low-carbon, green, high-quality steel. Based on the ion-molecule coexistence theory, this study establishes a thermodynamic model and carries out experimental studies under typical high scrap steel ratio conditions. It systematically examines the dephosphorization behavior of the CaO–SiO₂–FeO–MgO–P₂O₅ slag system at 1873 K, quantifies the influence of slag composition on the phosphorus distribution ratio, and reveals the mechanism by which the scrap steel ratio promotes dephosphorization through its effect on the phosphorus activity coefficient. Experimental results indicate that for highly efficient dephosphorization, the slag system’s basicity should be controlled between 2.5 and 3, with FeO content ranging from 25% to 30%. Under these conditions, the phosphorus content in the final molten steel can reach 0.005–0.01%, achieving a dephosphorization rate as high as 93–97%. Further research revealed a synergistic equilibrium relationship between basicity and FeO: excessively high basicity weakens dephosphorization due to thermodynamic saturation and increased viscosity, while FeO exceeding critical levels exerts a negative effect through dilution and elevated P₂O₅ activity. The final slag system achieved a phosphorus distribution ratio of 4.17–4.61 and an apparent mass transfer coefficient of 1.94–2.43 cm³/s. These findings provide critical theoretical and parametric foundations for slag system design and process optimization in high-quality steel production within electric arc furnaces.