Occurrence mode and molecular structure model of unburned carbon in coal gasification fine slags

Coal gasification fine slag (CGFS) is a kind of solid waste produced in the process of coal gasification, in which unburned carbon (UC) severely restricts its resource utilization. The study of physical/chemical properties, occurrence state and molecular structure of UC is of great significance to the utilization of CGFS. The characterization results show that the carbon content of particles increases with the increase of particle size, which is enriched to concentrate in particle size above 125 μm. UC is loose and porous, which leads to the wrapping and covering with inorganic ash particles. The molecular formula of the UC is determined to be C178H73O46N1S1, with a molecular weight of 2991. The average macromolecular structure model of UC is established by computer simulation. It is basically consistent with the infrared results of the simulation experiment. From the perspective of structure, UC has a high degree of aromatization and abundant oxygen-containing functional groups, which may increase the difficulty of decarbonization by enhancing hydrophilicity. This work provides a comprehensive understanding of UC structure at the atomic level, which is conducive to the efficient decarbonization of CGFS.