Coke degradation in blast furnace ironmaking: A comprehensive study of ore–coke interactions in a coupled system

This study investigates the dissolution behavior of coke in blast furnace (BF) ironmaking to reveal its property evolution mechanism during its interaction with iron ores at high temperatures. An experimental instrument, based on the improvement of the traditional softening-melting performance test, was developed to simulate the alternating layered structure of ore and coke and examine the degradation mechanism of coke under conditions close to those in actual BF operation—where ore and coke interact synergistically. Systematic experiments were conducted on three industrial coke samples with different reactivity levels. Results demonstrated a distinct spatially stratified pattern of coke degradation, occurring mainly in the layer adjacent to the ore. Furthermore, the degradation behavior of coke varied with its reactivity: coke with lower reactivity showed the fastest degradation rate during the middle stage of the reaction, whereas highly reactive coke experienced accelerated degradation in the later stages. Quantitative analysis identified two predominant reaction modes and their proportional relationship: the edge reaction, which reduces the coke size, and the uniform reaction, which damages the internal structure of coke. Their ratio varied according to coke reactivity and the reaction stage. In conclusion, coke degradation under realistic BF conditions is a complex, layered, multistage process whose mechanism transcends the scope of traditional evaluation indicators. These findings provide an important theoretical basis for accurately assessing coke performance and optimizing BF operation to enhance efficiency and stability.