Abstract: Short-process steelmaking is a key approach to promoting the green and low-carbon transformation of China’s steel industry. As the core equipment of this route, the electric arc furnace (EAF) is often constrained by limited bath stirring and metallurgical efficiency, which hinders its wider application. In this study, the flow behavior and mixing characteristics of a three-hole bottom-blown EAF under different gas flow rates and combined side-bottom blowing conditions were systematically investigated using both physical and numerical simulations. A 1∶8 scale water model experiment was conducted to examine bath mixing under varying bottom-blowing and side-bottom combined blowing operations, while a three-dimensional CFD model was established to analyze the velocity distribution at the steel-slag interface under different blowing parameters. The results show that the position of the bottom nozzles significantly affects bath stirring and interfacial mass transfer. With increasing the distance from the nozzles to the furnace center, the mixing time increases, while the dead-zone area at the steel-slag interface first decreases and then increases. The optimal nozzle location is 0.4R-0.5R. Under single bottom-blowing conditions, there exists an optimal flow rate range (0.1-0.32 L/min, corresponding to 20-60 L/min at industrial scale), beyond which stirring efficiency saturates. Side-bottom combined blowing can generate a through-circulation flow field and significantly improve mixing efficiency. However, when the bottom-blowing rate exceeds 0.63 L/min (120 L/min at industrial scale), the mixing efficiency declines. These findings provide theoretical guidance for optimizing EAF blowing operations, with important implications for improving the efficiency of short-process steelmaking and reducing energy consumption and carbon emissions.

Key words: electric arc furnace, bottom-blowing stirring, gas flow rate, nozzle position, mixing time