Effect of MgO on the Dissolution Behavior of Lime in Dephosphorization Slags for Double Slag Refining in Basic Oxygen Furnace

The rapid and complete dissolution of lime in the steelmaking process enhances dephosphorization and desulfurization rates, reduces slag emissions, and improves slag utilization efficiency. Extensive studies have been conducted to investigate lime dissolution mechanisms under static and dynamic conditions. Because steelmaking furnace linings primarily consist of MgO‐containing materials, slags typically contain MgO, which influences lime dissolution. However, the mechanistic role of MgO in lime dissolution in steelmaking slag systems remains unclear. In this study, the effect of MgO on the dissolution behavior of lime in CaO–SiO 2 –20%FeO–5%P 2 O 5 –MgO slag with varying MgO content (0–10 wt%) is investigated. The results show four regions around the lime surface: an unmelted CaO region, a CaO–FeO–MgO layer, compound and solid‐solution layers, and the original slag region. The formation of solid compounds and solid‐solution layers hinders lime dissolution. The average dissolution rate of lime gradually increases, reaches its maximum at 5 wt% MgO, and decreases with further increases in MgO content. The mechanism underlying the MgO effect on lime dissolution is discussed based on the dissolution path, X‐ray diffraction analysis, and viscosity calculations.