Akira Moriyama1, Jyunichiro Yagi1 and Iwao Muchi1
1Department of Iron & Steel Engineering, Faculty of Engineering, Nagoya University, Nagoya
An analytical study has been carried out on the rate-determining steps of the reduction of an iron-oxide pellet by hydrogen gas. Assuming that the diffusion through the gaseous film around the pellet, the intraparticle diffusion and the chemical reaction proceeds steadily in succession during the reduction process, the comprehensive rate equation (6) is derived in consideration of the resistance of each process. On the basis of the available data of various experimental conditions for the reduction of an iron oxide, the values of the fractional reduction calculated from Eq. (6) are compared with the observed values in the experiments mentioned above. The result shows a satisfactory agreement between the two.
The ratios of the resistance of each process to that of the over-all reduction process are evaluated quantitatively and illustrated graphically as functions of the particls size, porosity, fractional reduction, gas velocity and reaction temperature. Thus, the relation between the rate-determining steps and the operating conditions of the reduction process has beem clarified.
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