IMPROVEMENT IN THE REDUCIBILITY OF WUSTITE ASSISTED BY THE INTENSIFIED SURFACE SEGREGATION OF CALCIUM-IONS BY THE DOUBLE ADDITION OF CAO AND SIO2

In an iron-making blast furnace, wustite is usually doped with relativ ely low concentration levels of CaO, SiO2, and Al2O3. The effect of th e interaction between CaO and SiO2 dissolved in wustite on the reducti on was investigated in concentration levels as low as 0.05 mol pct. Th e double addition of SiO2 to CaO-bearing wustite has been found to int ensify-its reducibility greatly, improving the effect of the-single ad dition of CaO. The double addition also greatly intensifies the segreg ation of Ca ion at the surface of wustite, causing the wustite lattice to contract due to the interaction of CaO with SiO2. Ultimately,the i mprovement in the reducibility of wustite is attributable to the inten sified surface segregation of Ca ion, which facilitates the formation of a porous type of reduced iron. An additional conclusion is that CaO and SiO2, even at low concentration levels below the detection limit of electron probe microanalysis, can give the decisive effect to the r eduction of wustite.