Effect of residual volatile matter on reduction of iron oxide in semi-charcoal composite pellets

Abstract

Japanese cypress was carbonized partly at maximum carbonization temperatures TC,max=823, 1073 and 1273 K in order to obtain semi-charcoal with some residual volatile matter (V.M.). The semi-charcoal obtained at TC,max=823 K retained much V.M., mainly H2. Then, the semi-charcoal composite pellets have been prepared and reduced at reduction temperature TR=1073, 1173 and 1273 K in N2 gas atmosphere. Fractional reduction F(%) after 60 min of the carbon composite pellet using semi-charcoal particle with the size of 63-75μm at T C,max=823K was 19% at TR=1073 K and 40% at T R=1173K, and was higher than any other pellets. Fractional reductions F(%) of the semi-charcoal composite pellets at TC,max=823, 1073 and 1273 K were over 90% for 60 min at TR=1273 K. The reducibility of semi-charcoal composite pellets was did not depend on residual V.M. at T R=1273 K. On the other hand, fractional reduction F(%) of the semicharcoal composite pellet at TC,max=1073 K using semi-charcoal with the particle size of 23-35μm was 38% for 60 min at TR=1173 K, and was higher than any other pellets using semi-charcoal with the particle sizes of 63-75 and 105-150 μm. As the size of semi-charcoal particle decreased, the reduction of iron oxide was much enhanced at TR=1 173 K. © 2010 ISIJ.