Thermogravimetric (TG) data on reoxidation behaviour of a particular type of sponge iron (coal based sponge iron) are mainly reported in this paper. While emphasis is on isothermal kinetics, some nonisothermal TGdata are also presented. Thedata have been analysed using the reduced time plot and the activation energy values evaluated using both integral and differential approaches. The kinetic analysis developed has been used to establish the reaction mechanismwhich is found to be essentially of the first order. The paper also discusses the general importance of high temperature studies in the assessment of reoxidation behaviour of sponge iron and howthe outcomeof this investigation may be useful for devising means to protect sponge iron against reoxidation and spontaneous combustion.
SynopsisIn the present investigation hematite samples were reduced to magnetite by a mixture of H2 and H2O at 650, 700, and 750°C. These data have been analysed with the Johnson-Mehl equation and found to fit well in the nucleation and grain growth model. Activation energy values of the reaction were calculated by di fferent methods and have been found to match closely.
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