1999 Volume 85 Issue 6 Pages 452-459
Using a laboratory scale fine particles-gas conveyed bed, the reduction rates of liquid wustite with CO gas were measured. CO-CO2 mixtures having various flow rates and compositions were flowed downward through a cylindrical reactor maintained at a constant temperature of 1723 to 1823K. A batch of pure spherical wustite particles (mean dia.: 48.5 μm) was concurrently fed into the reactor at a small constant rate and reduced in a hot zone.
The reduction process was found to proceed in such a manner that metallic iron particles were enclosed inside a wustite droplet. Rate analysis was made of one dimensional mass balance equations for particles and gas in a steady moving bed under an isothermal condition using the reaction rate for a single particle taking the shrinkage into consideration. Under relatively small reducing potentials, it was concluded that the major fraction of overall reaction resistance is attributable to chemical reaction. However, under higher reducing potentials, the reduction process was estimated to include some mass transfer resistances within the liquid oxide phase. From the temperature dependence of forward chemical reaction rate constants, the activation energy was evaluated to be 90.6 kJ/mol.