Physical and numerical modelling permeability of blast furnace shaft zone with iron ore briquettes

Abstract

The briquetting technique holds significant potential to replace traditional iron burden materials due to its lower greenhouse gas emissions. In addition to briquettes’ thermomechanical and metallurgical properties, the blast furnace performance is also considerably affected by the ferrous burden permeability concerning the gas rising through the shaft zone of this reactor. Therefore, this study focused on bed permeability and pressure drop characteristics of iron ore briquettes compared to blast furnaces’ traditional iron ore burdens. Using laboratory experiments and computational fluid dynamics simulations, the research evaluates how different iron burden materials affect gas flow in the blast furnace shaft. The materials tested include sinter, pellets, lump ore, and two types of briquettes (B1 and B2), assessed in both single and mixed beds. The experimental and simulation techniques were in good agreement, and the results indicate that single beds of lump ore, sinter, and briquette B2 exhibit higher permeability, while beds composed exclusively of pellets or B1 briquettes showed lower void fractions, resulting in greater resistance to gas flow and the highest pressure drop. In single beds of B1 briquettes, the pressure drop was approximately 20% higher than that of sinter, while B2 briquettes demonstrated similar permeability and pressure drop to sinter under blast furnace conditions. Mixtures containing pellets also showed increased pressure drops, especially when the pellet mass fraction exceeded 25%, with pressure drops rising by up to 45% compared to sinter beds. Comparisons at varying substitution ratios further indicated that binary beds composed with B1 or B2 performed similarly up to a 50% substitution ratio; however, at a 75% substitution, B2 beds achieved a 10% lower pressure drop than B1 overall, making B2 a potential substitute for sinter to reduce CO₂ emissions. These findings underscore the critical role of material geometry and size distribution in optimising blast furnace efficiency.