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

Abstract

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.

Metallurgical Coke Combustion with Different Reactivity under Nonisothermal Conditions: A Kinetic Study

“…Therefore, the quality of metallurgical coke is closely related to the technical and economic indicators of blast furnaces. Mansheng et al found that from 1100 °C to 1500 °C, the coke weight-loss ratio increased by 10-fold, and the drum strength decreased by 80%; in a CO 2 atmosphere, when the temperature increased from 1100 °C to 1300 °C, the coke reactivity increased by 50%, and the coke strength decreased after the reaction [ 13 ]. Zhongsuo used different methods to analyze the kinetics of carbon dioxide gasification of metallurgical coke, and proposed new kinetic equations and predicted kinetic curves [ 14 ].…”

Coupled Typical Coke Gasification and Sintering Ore Reduction in CO–N2–H2

“…The carbon structure and pore characteristics of metallurgical coke have a significant impact on coke behavior and reactivity in a blast furnace. The basic unit of the carbon structure is a graphite crystallite, and the size of the graphite crystallite can usually be characterized by the stacking height Lc of the carbon substrate. , In this study, the stacking height Lc was calculated using Origin. First, the XRD data was drawn, and then the “multipeak fitting” was carried out.…”

Effects of Additives on Coke Reactivity and Sulfur Transformation during Co-pyrolysis of Long Flame Coal and High-Sulfur Coking Coal

“…Therefore, the microcrystalline structure of coke is an important factor affecting coke reactivity. 24 Figure 2 shows the XRD spectra of coke obtained from coal blends with different proportions of GL. The addition of GL weakens the peak intensities of 002 and 100, which represent the size and orientation of the carbon reticulum layer in the aromatic ring of coke, respectively.…”

“…The edge of the coke microcrystal belongs to the defect site of the crystal lattice, which can form unsaturated chemical bonds easily by combining heteroatoms, and becomes the active center during gasification reaction to promote the gasification activity. Therefore, the microcrystalline structure of coke is an important factor affecting coke reactivity Figure shows the XRD spectra of coke obtained from coal blends with different proportions of GL.…”