2005 Volume 91 Issue 6 Pages 521-527
Acceleration of reduction rate and decrease of reaction temperature in ironmaking process are key issues to reduce the CO2 emission and the energy consumption. To solve the problem, effective use of H2 gas or CH4 gas including both reducing agent of carbon and hydrogen is proposed. Therefore, a laboratory scale fine iron are particles-gas conveyed system was utilized to measure the reduction rates of fine are by using H2 and CH4 gas at high temperature. H2-N2 and CH4-N2 mixture having various flow rates and compositions were flowed downward with fine iron are through a cylindrical reactor maintained at a constant temperature of 1373 to 1723K.
The reduction process was found to proceed in such manner that the iron are particles were reduced topochemically under the condition of 1573K. The reduction rate in CH4 gas became larger than that in H2 gas with increase in the temperature, because of the contribution of carbon deposited on the surface of iron are particle. Fractional reduction of ore in CH4 gas reached over 0.8 at 1573K in 1 s. In the reaction rate analysis, it was concluded that the major fraction of overall reaction resistance was attributable to chemical reaction between the iron oxide and the carbon dissolved in metallic iron. The activation energy in CH4 reduction was evaluated to be 192.5kJ/mol and it was almost same as that in decomposition of CH4.
