COガス輸送層による酸化鉄の溶融還元

抄録

The kinetics and mechanism of reduction of molten iron oxide with CO gas at high temperatures of 1450°C and 1600°C were investigated. In order to reduce the influence of mass transfer rate on overall reaction rate of reduction, fine powders of iron oxide were used as specimen and were reduced in a transport reactor. The specimens of fine powder of reagent grade were melted during falling down in reaction zone and liquid oxide drops were reduced with CO gas. Mean diameter of liquid particles was 25μ.
The oxide particles were melted and became spherical, and the reduced iron was surrounded by liquid FeO. It is considered that liquid FeO always existed on the spherical surface and the nucreation, growth and cohesion of iron in liquid drop did not influence the overall reaction. The results were analysed by considering only the mass transfer in a gass film and the chemical reaction at the gas liquid interface.
The value of mass transfer coefficient k_g was estimated by using the Ranz-Marshall equation. Considering the shrinkage of particles by production of metallic iron, the values of rate constant of chemical reaction k_c were obtained as 19.4cm/s at 1600°C and 9.3cm/s at 1450°C.