Industrial experimental study on rotary stirring injection desulfurization method

Desulfurization in hot metal pretreatment is a critical process for enhancing steel quality. This study investigates the effects of impeller blade number and rotational speed on desulfurization efficiency in a 200 t hot metal rotary stirring injection desulfurization system at a steel plant. Experimental results demonstrate that when the rotational speed increases from 30 to 120 r/min, the desulfurization rates for two-blade, three-blade, and four-blade impellers increase by 114%, 47%, and 39%, respectively. Under the rotary stirring injection conditions tested, the desulfurization rate ranges from 0.0027 to 0.0062%/min, significantly higher than those achieved by traditional KR mechanical stirring and compound injection technologies. At the same rotational speed, the four-blade impeller yields the highest desulfurization rate. The desulfurization efficiency exceeds 90% in all experimental heats, with higher blade counts and rotational speeds leading to improved desulfurization. Under the configuration of a four-blade impeller at 90 r/min, magnesium utilization reaches a maximum of 83.5%, substantially higher than that of conventional magnesium powder injection technology. SEM-EDS analysis of hot metal bubbles captured by the U-shaped plate indicates that bubble sizes are predominantly distributed between 100 and 500 μm, primarily in the form of discrete spheres. The average bubble size decreases with increasing rotational speed. At higher rotational speeds (90 and 120 r/min), the four-blade impeller exhibits strong bubble breakup capability, resulting in an average bubble size of 215–220 μm. By integrating injection methods with mechanical stirring, the rotary stirring injection desulfurization technology refines bubble size while enhancing molten bath fluidity, enabling deep desulfurization and efficient utilization of desulfurizing agents.