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.