Interaction Mechanism and Microstructural Evolution of Ferrous Burdens in the Cohesive Zone Based on Blast Furnace Dissection

Understanding ferrous burden interaction and microstructural evolution within the cohesive zone (CZ) is essential for low‐carbon blast furnace ironmaking. This study investigates the 3D structural evolution and interaction mechanisms of CZ burdens using core samples from a 2200 m ³ dissected commercial BF and serial sectioning 3D reconstruction. The CZ exhibited an “overall inverted‐V shape with a winged periphery” across the lower shaft to middle bosh. From the outer to the inner boundaries, the reduction degree and metallization rate of the burden increased from ~41.06% and ~28.46% to ~77.85% and ~71.95%, respectively. 3D mineralogical analysis revealed that the homogeneous pellet–pellet interfacial interaction was dominated by mutual slag dissolution, forming a symmetric structure that widened from 150 μm to approximately 2.50 mm. Conversely, the heterogeneous pellet–sinter interfacial interaction was driven synergistically by slag reactions and composition gradients, developing a layered structure with its width increasing from 110 μm to approximately 2.00 mm. The interaction process comprises three stages: localized initial slag bonding, intensified slag interaction with iron phase growth, and structural densification. These findings provide a theoretical basis for optimizing blast furnace operations and the rational burden structure.