Effect of Residual Volatile Matter on Reduction of Iron Oxide in Semi-charcoal Composite Pellets

摘要

Japanese cypress was carbonized partly at maximum carbonization temperatures T_(C,max)=823, 1 073 and 1 273 K in order to obtain semi-charcoal with some residual volatile matter (V.M.). The semi-charcoal obtained at T_(C,max)=823 K retained much V.M., mainly H_2. Then, the semi-charcoal composite pellets have been prepared and reduced at reduction temperature T_R=1 073, 1 173 and 1 273 K in N_2 gas atmosphere. Fractional reduction F(%) after 60min of the carbon composite pellet using semi-charcoal particle with the size of 63-75μm at T_(C,max)=823 K was 19% at T_R=1 073 K and 40% at T_R=1 173 K, and was higher than any other pellets. Fractional reductions F(%) of the semi-charcoal composite pellets at T_(C,max)=823, 1 073 and 1 273 K were over 90% for 60min at T_R=1 273 K. The reducibility of semi-charcoal composite pellets was did not depend on residual V.M. at T_R = 1 273 K. On the other hand, fractional reduction F(%) of the semi-charcoal composite pellet at T_(C,max)=1 073 K using semi-charcoal with the particle size of 23-35 μm was 38% for 60min at T_R=1 173 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 T_R=1 173 K.