Mathematical Modeling of Material–Energy–Carbon Flows and Techno-Economic Analysis of Ternary Hot Metal, Scrap, and Direct Reduced Iron Charges in Electric Arc Furnace Steelmaking in China

A static material–energy–carbon model rebalances ternary hot metal (HM), scrap, and direct reduced iron (DRI) charges to assess electricity, emissions, and costs, including upstream burdens, in Chinese electric arc furnace steelmaking. Under the specified coke oven gas-based DRI assumptions, complete replacement of HM reduced emissions by 348.5 kg CO2e/t molten steel, whereas replacement of scrap increased them by 1785.4 kg CO2e/t; this ranking persisted across grid scenarios. At 20% DRI, increasing HM from 0% to 50% saved 332.4 kWh and 61.5 USD but added 990.0 kg CO2e per tonne of molten steel. Under the baseline grid, separate fuel injection saved electricity; natural gas reduced net emissions, whereas carbon powder and the tested combined injection increased them. DRI at 298.5 °C matched cold scrap’s in-furnace electricity consumption; overall preheating benefits depended on external heat supply and efficiency. Higher metallization saved electricity, whereas slag and cost responses depended on composition closure. At equal slag basicity (R = 1.8) and scrap prices of 333–444 USD/t, DRI offered no cost advantage at 0% or 20% HM; at 50% HM, an advantage emerged only above approximately 440 USD/t. These findings support static screening of charge and energy options under specified conditions.