Title

KINETIC COMPENSATION EFFECT ON THE CARBOTHERMIC REDUCTION OF IRON OXIDES

KINETIC COMPENSATION EFFECT ON THE CARBOTHERMIC REDUCTION OF IRON OXIDES

Authorship

MOURÃO, MARCELO BREDA; NASCIMENTO, RAMIRO CONCEIÇÃO; TAKANO, CYRO

MOURÃO, MARCELO BREDA

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NASCIMENTO, RAMIRO CONCEIÇÃO

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TAKANO, CYRO

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DOI

10.5151/2594-357x-34Red-607-616

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Abstract

Several studies concerning the rate of the carbothermic reduction of iron oxides have come out in the last decades, due to the importance of this reaction in the new proposed processes of virgin iron production from carbonaceous materials. Kinetic studies have been performed for systems in which iron oxide and carbon, in particulate form, are mixed and the mixture is heated in a suitable apparatus. These studies have proposed kinetic equations capable to represent the reaction rate, and it has been usual to admit that the rate constant follows the Arrhenius law. Apparent activation energies and the respective pre-exponential factors of the Arrhenius law have been determined, and there is a great scatter among the results obtained by the different research groups. The present work shows that the two kinetic parameters obtained experimentally by different researchers and in different experimental conditions are related by an expression of the type ln A = a.E + b, where A is the pre-exponential factor and E the apparent activation energy obtained in the different experiments and a and b are constants, thus evidencing the occurrence of the so-called kinetic compensation effect for this system.

Several studies concerning the rate of the carbothermic reduction of iron oxides have come out in the last decades, due to the importance of this reaction in the new proposed processes of virgin iron production from carbonaceous materials. Kinetic studies have been performed for systems in which iron oxide and carbon, in particulate form, are mixed and the mixture is heated in a suitable apparatus. These studies have proposed kinetic equations capable to represent the reaction rate, and it has been usual to admit that the rate constant follows the Arrhenius law. Apparent activation energies and the respective pre-exponential factors of the Arrhenius law have been determined, and there is a great scatter among the results obtained by the different research groups. The present work shows that the two kinetic parameters obtained experimentally by different researchers and in different experimental conditions are related by an expression of the type ln A = a.E + b, where A is the pre-exponential factor and E the apparent activation energy obtained in the different experiments and a and b are constants, thus evidencing the occurrence of the so-called kinetic compensation effect for this system.

Keywords

carbothermic reduction, kinetic compensation effect, kinetics, iron oxides, Arrhenius law

carbothermic reduction, kinetic compensation effect, kinetics, iron oxides, Arrhenius law