Promoting effect on oxidation reaction of iron-bearing agglomeration agent by melt formation

This study was carried out to examine the way to suppress the CO₂ emissions from the iron ore sintering process through effectively utilizing the oxidation heat of iron containing material, namely iron-bearing agglomeration agent. Increase in the oxidation ratio of iron-bearing agglomeration agent in the process will lead to decrease in the amount of CO₂ emissions. In order to increase the oxidation ratio, the effect of melt formation in the iron oxide layer on the oxidation reaction of metallic iron particle covered by adhering layer of CaO, SiO₂ and magnetite ore was discussed. Changes in the O₂ concentration in outlet gas and sample bed temperature were measured by using a laboratory scale sintering simulator. Oxidation ratios of samples were calculated by the concentration of outlet gas. Oxidation ratio of metallic iron particles with adhering layer was higher than that of simple metallic iron particles. Melt formation of the iron oxide layer at surface of metallic iron particles would promote the oxidation compared to thatat solid state. When CaO concentration of the adhering layer was increased, oxidation ratio of metallic iron particle was increased until 50 mass%-CaO. In the case of CaO concentration more than 50 mass%, however, oxidation ratio was kept approximately 0.9. It suggests that an excess amount of melt formed on the surface of metallic iron particle seems to prevent the diffusion of oxygen. Adjusting the composition and amount of melt formed on the surface of iron-bearing agglomeration agent would lead higher reaction ratio.