China Nonferrous Metallurgy

Calcined petroleum coke is an important raw material of metallurgical carbon materials such as carbon anode for aluminum electrolysis. The existing research lacks of in-depth exploration of the microstructure evolution of calcined coke at different calcination temperatures, which makes it difficult to intelligently control and reduce the consumption of metallurgical carbon production. In order to solve the above problems, an intelligent extraction technology of lattice fringes of carbon materials based on HRTEM detection and mathematical fitting were used to investigate the evolution law of the microstructure of calcined coke at different calcination temperatures. When the temperature was below 600℃, the average lattice fringe length, total stacking frequency, and 45° contribution of the calcined cokes slightly deteriorated with the increase of temperature. While in the temperature range of 600 to 1600℃, the variation patterns of the characteristic values were consistent with the Sigmoid function model, which increased rapidly and then gently with the increase of temperature. The effective temperature intervals of the microstructure characteristics were obtained via the deduced formula of the fitting curves. The priority of the microstructure characteristics changing with temperature was as follows: lattice orientation ＞ lattice stacking ＞ lattice growth. The graphitization degree R of calcined coke varied from 0.86 to 0.59 in the temperature range of 25~1600℃ by Raman spectrum analysis. The evolution law of graphitization degree at different temperatures demonstrated the result of the variation patterns analysis of the above microstructure characteristics.