Impact of gasification on in-situ thermal strength of tamping coke and top-charging coke: Pore structure, carbon structure, and fracture mechanisms

Tamping coking technology has garnered attention in the ironmaking industry due to its resource efficiency and economic benefits. However, its adaptability under blast furnace conditions remains controversial, limiting its widespread application. Previous studies on tamping coke primarily focused on its cold mechanical strength, reactivity, and post-reaction strength, yet the degradation mechanisms of its in-situ thermal strength after gasification and its performance differences compared to top-charging coke under identical conditions remain underexplored. This study simulates blast furnace temperature and atmosphere to compare the thermal tensile strength of gasified tamping coke and top-charging coke via splitting tests. Results indicate that the strength of top-charging coke sharply declines at 1200 °C, while tamping coke retains 51.3 % higher strength. Gasification enhances coke anisotropy and disrupts pore structures, the latter being the primary factor for strength reduction. Fracture analysis reveals two failure modes: brittle overload fracture and defect-induced fracture, with the latter being more prevalent. Tamping coke exhibits fewer structural defects and milder gasification-induced damage, contributing to its superior thermal strength. This study provides new insights for evaluating coke performance under practical blast furnace conditions and supports the industrial adoption of tamping coke.