Evolution of Slag Properties and Burden Melting Characteristics During the Smelting of Low‐Grade Iron Ores

The increasing utilization of low‐grade iron ores poses significant challenges to the stable and efficient operation of blast furnaces. The gangue components in the ore affect slag fluidity and the permeability of the burden to gas and liquid. In this study, the coupled influence of slag properties, burden dripping behavior, and blast furnace performance was systematically investigated based on the principles of low‐grade burden smelting and long‐term industrial verification. The results show that with a burden ratio of 78% sinter + 14% pellet + 8% lump, the optimal coupling between the molten layer thickness and gas flow resistance is achieved, resulting in the minimum characteristic value S and improved gas–liquid permeability in the softening and melting zone. Increasing Al 2 O 3 content significantly increases slag viscosity and reduces superheating, thus narrowing the thermal operating window. When the Al 2 O 3 content is above 16 wt%, adding an appropriate amount of TiO 2 up to 1.5 wt% can effectively compensate for the adverse effects of Al 2 O 3 . Applying the proposed slag and burden design scheme in a commercial blast furnace showed that when the ore grade decreased from 57.5% to 56.5%, the blast furnace maintained stable operation with good permeability, lower fuel consumption, and higher production efficiency. This provides guidance for the efficient and stable smelting of Al 2 O 3 ‐TiO 2 ‐containing low‐grade iron ore in modern blast furnace ironmaking.