著者

森 一美

出版者

社団法人日本鉄鋼協会

雑誌

鐵と鋼 : 日本鐡鋼協會々誌 (ISSN:00211575)

巻号頁・発行日

vol.50, no.13, pp.2259-2260, 1964-11-01

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A rate equation has been derived for the gaseous reduction of iron ore pellets on the assumption that both chemical reaction and diffusion contribute to the overall reduction rate. It was assumed that there is no resistance of diffusion through the boundary layer outside the pellet and chemical reaction takes place only at the interface between reduced and unreduced layers. Under these conditions the rate equation is given as follows : (1/k)[1-(1-R)^<1/3>]+(r_o/D)[1/2-R/3-(1-R)^<2/3>/2]=(C_o-C_e)t/r_od_o where R : fractional reduction k : chemical reaction rate constant t : time D : effective diffusion coefficient r_o : radius of pellet C_o : gas concenration in the bulk gas phase d_o : density of pellet C_e : equilibrium gas concentration The two terms on the left side of the equation show the relative contribution by chemical reaction and by diffusion of the reducing gas through the reduced metal layer. It was found that the equation agrees with experimental data except towards the completion of reduction. Equation for the reduction controlled either by chemical reaction or by diffusion could be derived as the limitimg cases of the above-mentioned equation.