The Relationship Between The Optical Properties And The Chemical Structure Of The Vitrinite In Coking Coals

A lot of factors determine the quality of blast furnace coke, but in the current blast furnace production, many factors have been fixed. So coke quality depends mainly on the nature of the raw coal. The macroscopic properties of coal depend on the microscopic chemical structure, however, the chemical structure of coal is not uniform and complex. In order to fully understand the coal and a deep understanding of their relationship between caking properties and chemical structure of coking coals, so the combined of macroscopic nature and microscopic chemical structure is researched.Some representative coking coals with different coal ranks are selected in Tangshan area, including gas coal, 1/3 coking coal, fat coal and coking coal. The fluorescence parameters(FImax, FI450, FI470 ect.) for coking coals were determined using the threedimensional scanning fluorescence spectroscopy. The relationships between the fluorescence parameters and caking properties( caking index: G, Gieseler fluidity: lgα and Audibert-Arnu dilatometer: b) were analyzed.The results show that the fluorescence parameters first increase then decrease with the increase of reflectance and the maximum is 0.95%. The relationship of fluorescence parameters with reflectance is similar with caking properties. Fluorescence parameters have little difference with the increase of G(G <90), and increase linearly with the increase of G(G > 90). Thus, the fluorescence parameters are new index to evaluate the caking properties for the strongly caking coals.The chemical structure parameters(ratio of carbon hydrogen, aromaticity, hydrogen aromaticity etc.) were determined using the methods such as FT-IR、NMR and ultimate analysis etc. The relationships between chemical structure parameters and fluorescence parameters were analyzed. It aims at the study of the relationship between the caking properties and fluorescence characteristics in order to indicate the discrepancy of the thermoplastic properties with different coal ranks and establish bondability indicator evaluation model based on the fluorescence properties of vitrinite. The research results will play important role in fast evaluating caking properties of coking coals, directing coal blending coking and improving the coal blending theory theoretically and practically.