The reduction, carburization, and meit-down properties at high temperatures of pellets and sinter in packed beds were studied using a quenching method. The results obtained are summarized as follows:(1 ) Reduction retardation of pellets is attributed to the disappearance of the micropores caused by sintering of iron under the presence of a liquid exudedfrom the wustite core.(2) Carburization proceeds mainly through the diffusion of carbon from the iron surface, brought about by melting reduction, directly contacting solid carbon.(3) Improved pellet reduction retardation was brought about by adjusting the chemical composition of the core part to have a higher solidus temperature. The melt-down property was ameliorated by increasing the basicity of the entire pellet.

SynopsisThere exists a need to improve the high temperature reducibility and lower the softening rate of pellets in order to get high productivity in the blast furnace.This paper introduces the influence of the MgO/Si02 and the CaO/ Si02 ratios in pellets on the high temperature reduction and softening properties.The pellets whose MgO/Si02 ratio is held at above 0.6, and whose CaO/Si02 ratio is held at below 0.05, are proved to have better high temperature properties than those of acid or self-fluxed pellets. There was no deterioration in properties, even if the quantity of SiO2 is significant.