Assimilative Characteristics of Iron Ores and Their Influence on Sinter Qualities

Abstract

Sintering tests of 17 different systems of iron ores with 20% CaO were carried out in air atmosphere at 1 300°C for 2min. Some of them were also subjected to the pot sinter tests to clarify the relation between assimilative characteristics of iron ores and sinter qualities under uniform size distribution of iron ores and the same sintering conditions.
The results obtained are as follows:
(1) Volume shrinkage degree ε, regarded as an index of the assimilative characteristics of iron ore has close correlation with contents of goethite, SiO₂ and FeO in iron ore.
(2) The increase of the value of ε tends to increase formation of locally enhanced liquid phase which causes a weak structure and results in a decrease of sinter strength.
(3) The JIS reducibility index (RI) deteriorates with the increase of the value of ε. This is because, if the value of ε is larger, the enhanced liquid phase causes the formation of fused-type microstructure and the decrease of micropores.
(4) The value of ε is not sufficient to define their relationship with the reduction degradation index (RDI). Original iron ores can be divided into two groups; one tend to improve RDI and the other liable to deteriorate RDI. The index which is calculated from their characteristic value shows good correlation with RDI.