Study On Carbonization Mechanism And Modification Of Coal Tar Pitch

High-performance carbon materials are demanded due to rapid development of aluminum electrolysis industry. Coal tar pitch binder is one of key in process of preparing high-performance carbon materials. On the basis of coal tar pitch research in domestic and abroad, the comprehensive properties of the coal tar pitches and the influence of coal tar pitch on the performance of carbon materials were studied combined with the preparation of carbon product in this paper. The carbonization process and the generation of mesophase of coal tar pitch were studied. The modification of coal tar pitch used as binder for carbon anode in aluminum electrolysis industry with additives was studied in order to improve the comprehensive quality of coal tar pitches. Results obtained are listed as following.The characterization of coal tar pitches and correlation between coal tar pitch and calcined petroleum coke were studied. The results indicated that the viscosity-temperature curves can be analyzed by exponentiation fitting, whose correlation coefficients are even higher than that of Arrhenius formula fitting. The infiltration of pitches to coke bed is influenced by temperature and the coke particle size distribution. Permeability-temperature curves are similar to viscosity-temperature curves, including three temperature ranges (sensitive range, transition range and stable range).TG-DTA, components analysis, XRD and polarization microscope method were used to study the mechanism of coal tar pitch carbonization and the mesophase produced in the heat treatment. The analysis show that the carbon yields is not only decided by components content and softening point, but also by the degree of decomposition and dehydrogenation during the pyrolysis. The existence of calcined petroleum coke will help increase carbon residue of coal tar pitch in the process of carbonization. Appropriate additive can inhibit the generation of mesophase in the coking process. On the basis of study on the effect of single additive on coal tar pitch, kinds of combined agents were used to modify the coal tar pitch and their effect on the fluidity, coking value, softening point and components content of pitch were ananlyzed. Results show that some combined agent can improve the rheologial behavior effectively. And resistance of binder coke to air and CO2 reactivity of binder coke can be improved to some degree.