A laboratory-based investigation into the catalytic reduction of NO x in iron ore sintering with flue gas recirculation

Abstract

The catalytic reduction behaviours between NO _x and CO in sinter zone were studied as using flue gas recirculation (FGR). Minerals in sinter can act as catalysts during NO _x reduction. The catalytic activity of minerals has the order of calcium ferrite > kirschsteinite > fayalite. The catalytic procedure includes two steps: iron-bearing minerals are reduced to lower valence oxides by CO, and then NO is reduced to N₂ by lower valence oxides. Improving the generation amount of calcium ferrite, especially acicular-type silico-ferrite of calcium and aluminium (SFCA), contributes to significantly reinforcing the catalytic performance between NO and CO. As the basicity of sinter increases to 2.2, it enables to generate maximum amount of acicular-type SFCA which has larger specific surface areas, therefore facilitates decreasing NO _x emission during FGR sintering.