A Comprehensive Review of Characterization Methods for Metallurgical Coke Structures

Abstract

The structure of coke affects its reactivity and strength, which directly influences its performance in the blast furnace. This review divides coke structures into chemical structure, physical structure, and optical texture according to their relevant characteristics. The focuses of this review are the current characterization methods and research status of the coke structures. The chemical structures (element composition and functional group) can be characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance imaging technology (13C NMR). The physical structures (pore structure and micro-crystallite structure) can be characterized by image method, X-ray CT imaging technique, mercury intrusion method, nitrogen gas adsorption method, X-ray diffraction method (XRD), and high-resolution transmission electron microscopy (HRTEM). The optical textures are usually divided and counted by a polarizing microscope. In the end, this review provides an idea of the construction of a coke molecular structural model, based on the above characterization. With the coke model, the evolution principles of the coke can be calculated and simulated. Hence, the coke performance can be predicted and optimized.

Investigation into the Effect of Multi-Component Coal Blends on Properties of Metallurgical Coke via Petrographic Analysis under Industrial Conditions

“…According to [64] the R 2 is 0.894 for the relationship between CRI and CSR. The resulting coefficient is slightly lower than indicated by [64] and below the R 2 = 0.977 value indicated in [46,61]. In addition, using equations that describe the relationship between CRI and CSR, for example, CRI = 52.547-0.397•CSR in paper [65], and CSR = −1.6884•CRI + 102.38 [66], to assess the quality of the obtained coke leads to an underestimation of the values of the parameters in comparison with those obtained in this study.…”

“…It can be seen that the M 25 and M 10 values of cokes are quite stable within the ranges from 87.3 wt.% to 88.8 wt.% and from 7.2 wt.% to 7.8 wt.%, respectively. It is well known that the CSR parameter negatively correlates with the CRI parameter, and this relationship can be vice versa [61][62][63]. Figure 5 shows that with a decrease in the CRI of coke, the CSR increases.…”

Co-Carbonization of Discard Coal with Waste Polyethylene Terephthalate towards the Preparation of Metallurgical Coke

“…A typical XRD pattern of graphitic carbons consists of diffraction peaks at 24–26°, 44°, and 81°, which represent the (0 0 2), (1 0 0), and (1 1 0) planes, respectively [ 39 , 40 , 41 ]. Analysis of these specific peaks gives information about the structure of graphite microcrystallites, including the average stack height or ordering of graphite planes, and the size of hexagonal ring structures.…”

“…In general, the peak width of the (0 0 2) plane at 24–26° relates to a high microcrystallite ordering when the peak is narrow, whereas a broad peak typically relates to a less ordered microcrystallite structure. In addition, the higher and narrower the (1 0 0) and (1 1 0) planes are related to the large-sized hexagonal rings [ 39 ].…”

Classifying coke using CT scans and landmark multidimensional scaling

“…There is a recent study in microstructure analysis and mineral phase transformation in blast furnace (Wu et al 2022). We also point out a recent review paper focussing on the current characterisation methods of the coke structure (Zheng et al 2021). Earlier, Raman spectroscopy is also applied to predict the coke quality (Rantitsch et al 2014).…”