Thermal Simulation Experiments on Smelting Characteristics and Dephosphorization in Converter with High Scrap Ratio

Smelting with a high scrap ratio in converters holds significant importance for carbon reduction and emission reduction in the iron and steel industry. Under high scrap ratio conditions, the kinetic and thermodynamic conditions of the molten bath change significantly, leading to considerable differences in the elemental reactions and slag formation patterns during the smelting process. To investigate the reaction characteristics and dephosphorization behavior of the molten bath under different scrap ratios, this study conducted thermal simulation experiments of converter smelting with four scrap ratios (20%, 30%, 40%, and 50%) using a 500 kg induction furnace. Scrap preheating and supplemental heating agents were applied as needed. Slag petrographic analysis was carried out using SEM and EDS. The experimental results indicate that with scrap ratios of 20% and 30%, the carbon–oxygen reaction and slag formation efficiency are relatively high. The dephosphorization rate in the early stage of smelting can exceed 50%, and phosphorus is effectively enriched in the CaO–SiO2 matrix phase, with the highest phosphorus distribution ratio observed at a 30% scrap ratio. In contrast, with scrap ratios of 40% and 50%, the carbon–oxygen reaction is slower, and the dephosphorization rate in the early smelting stage is less than 10%. In the 40% scrap ratio experiment, phosphorus began to accumulate significantly in the dicalcium silicate phase during the mid-smelting stage as the basicity increased. At a 50% scrap ratio, the silicate matrix remained the dominant phase throughout all smelting stages, and no distinct phosphorus-rich phase was formed.