Characterizing the Vertical Heterogeneity in Ultra-High Bed Sintering: From Mixture Properties to Stratified Phase Composition and Sinter Strength

With the growing demand for efficiency, low consumption, and environmental sustainability in the iron and steel industry, ultra-high bed sintering technology emerges as a research hotspot due to its advantages in significantly reducing fuel consumption and pollutant emissions. However, studies on the influence of fuel on mineralization behavior under ultra-high bed sintering conditions remained limited. This study systematically analyzes the effects of particle size, chemical composition, alkalinity, and MgO/Al2O3 ratio on mineralization behavior using a 500 m2 sintering machine, while evaluating the tumbler strength and phase composition of the sinter. The results reveal that particle size segregation in the mixture was primarily caused by the upper layer, with the lower layer having a lesser impact on overall segregation. Chemical composition also exhibited significant segregation, particularly in TFe and fuel distribution along the bed height. Fuel segregation was pronounced vertically but negligible horizontally. Under the current fuel distribution, uneven heat distribution was observed, with excessive heat in the lower layer leading to increased liquid phase formation, reduced porosity, and improved sinter strength downward along the bed. Additionally, the phase composition varied markedly across layers: hematite content gradually increases from top to bottom, calcium ferrite (SFCA) content peaks in the middle layers, and magnetite decreases with bed depth.