Study on the interaction and coking characteristics of low-sulfur meager coal and medium-high sulfur fat coal during co-carbonization process

To expand the scope of coking coal resources and realize the efficient utilization of different types of coking coals, medium-high sulfur fat coal (FC1, FC2) and low-sulfur meager coal (MC) were selected to explore the influence of co-carbonization process on the final coke properties. Using 13C NMR, Raman and FTIR characterization, it is found that FC1 has a higher content of methylene and aromatic bridge carbon, multiple aromatic structure of 3–5 benzene ring, strong branching degree and hydrocarbon generation ability than FC2, which promote FC1 to produce more liquid phase products in the thermoplastic stage, form higher mobility and better fuse with MC. Comparing the properties of coke with different ratios, it is found that the proportion of MC added in FC1 could reach 60%, the cold-state strength of coke was improved and the deterioration of thermal-state strength was unobvious. When the amount of MC in FC2 is 40%, better coke performance can be obtained. This is mainly due to the fact that the actual volatile released during the pyrolysis of FC1 and FC2 combined with MC is higher than the calculated value, this promoted the pyrolysis of Car-Cal/O and inhibited the pyrolysis of Cal-Cal and Car-Car, resulting in more intermediate molecular weight aromatic nuclei and higher 3–5 membered ring structure content in the thermoplastic process, thus improving the coke quality.