Analysis of Reduction Rate of an Iron Oxide (Wustite) Pellet with H2-N2 and CO-N2 by Unreacted-core Model
1982 Volume 68 Issue 15 Pages 2253-2262
Details
1982 Volume 68 Issue 15 Pages 2253-2262
Reduction experiments of wustite pellets with H2-N2 and CO-N2 gas mixtures of various compositions were carried out at 1000°C. The wustite pellets were prepared by partial reduction of pure hematite pellets (about 3.9 g in weight, about 0.62 cm in radius, and 0.200.25 in porosity) in 50%CO-50%CO2 gas mixture at 1000°C. The rate parameters contained in the unreacted-core model were determined by applying the methods of the mixed-control plot and the data-fitting to the reduction data.
In the reduction with H2-N2, the rate parameters for both the reactant gas and the product gas should be estimated. The relation between the effective diffusion coefficient in the product layer and the N2 gas concentration XN2, is explained in terms of the dependency of the ternary diffusion coefficient on XN2, but the relation between the apparent chemical reaction rate constant and XN2 cannot be solely explained by that effect. The change of the specific surface area of solid reactant during the reduction should also be taken into account.
In the reduction with CO-N2, the effect of N2 gas concentration on the reduction mainly results from the change of the driving force of the reduction.
