Influence of Temperature and CO₂ on High-Temperature Behavior and Microstructure of Metallurgical Coke

Metallurgical coke is an important raw material for blast furnaces. Specifically, temperature and CO₂ significantly affect its metallurgical behavior. In this study, the influence of temperature and CO₂ on the high-temperature behavior of three metallurgical coke samples, used in blast furnaces of different volumes, was investigated. The carbon structure and pore structure of the coke samples were analyzed. The results indicated that as the temperature increased from 1100 to 1500 °C, the weight loss ratio increased 10-fold and the drum strength decreased to approximately 80% in Ar. Under a CO₂ atmosphere, as the temperature increased from 1100 to 1300 °C, the reactivity index increased from 20 to 70%, and the strength after reaction exhibited the lowest value of 40% at 1250 °C. When the temperature increased from 1100 to 1500 °C, the stacking height of the layer structure Lc of the coke samples increased to ∼5.5 nm. Under the influence of CO₂ and temperature, the Lc of the coke samples increased to approximately 4 nm between 1100 and 1300 °C. Furthermore, CO₂ slightly affected the carbon structure. The changes in pores under the influence of CO₂ and temperature were greater than those under the influence of temperature between 1100 and 1300 °C. Typically, the strength of coke is high when the pore number, roundness, and porosity are low. The strength and microstructure parameters of the coke samples were correlated via multiple regression. The results of the multiple regression showed that the carbon structure and pore number had the highest impact on coke strength, followed by roundness and porosity.