Kinetic triplet from low-temperature carburization and carbon deposition reactions

Carbon deposition reaction is unfavorable for smooth operation of blast furnace, while the product of carburization reaction is a superior iron-bearing raw material in non-blast furnace routes. The kinetic triplet of these two reactions was obtained based on non-isothermal kinetic analysis. According to the Sharp–Wentworth method, the activation energy of the carburization reaction is 397.77 kJ/mol, and the activation energies of the carbon depositions on hematite and magnetite are 188.92 and 100.89 kJ/mol, respectively. The carburization reaction is controlled by the Jander mechanism, and the carbon depositions on hematite and magnetite are both controlled by the mechanism of Zhuravlev–Lesokhin–Tempelman. Based on Coats–Redfern method, the activation energies of the above three reactions are 360.65, 149.29, and 102.36 kJ/mol, respectively. The carburization reaction is a first-order reaction, while the carbon depositions on hematite and magnetite are both third-order reaction. In particular, the negative activation energy is obtained if considering the anti-Arrhenius circumstance in the Sharp-Wentworth method. Based on above results, it is feasible to adopt non-isothermal kinetic method to study the kinetic triplet of a reaction. According to the obtained activation energies and reaction mechanism functions, the simulated kinetic data are in good agreement with the experimental values even using the negative activation energy.