2021 Volume 61 Issue 1 Pages 79-85
Properties like shatter index and yield of the top layer of iron ore sinter in a Dwight-Lloyd sintering machine have always been a bottleneck for improvement of overall sinter quality due to the practical limitation of achieving high sintering temperature and dwell time in the top layer. To improve the sinter yield and shatter index of top layer, various technologies like usage of additional coke breeze, gaseous fuel injection and oxygen enrichment have been reported. In this paper, effect of oxygen enrichment of the incoming air on top part of the sinter bed was investigated using pot sinter experiments with varying oxygen percentage of 0 to 12 vol.% in the incoming air for an initial duration of 1/3rd of the total sintering time. It was observed that with increasing oxygen percentage from 0 to 9 vol.% in the incoming air, top layer sinter yield increased from 76.1 to 80.6% and shatter index from 69.0 to 74.8%. The improvement in sintering properties were mainly attributed to the promotion of sintering reaction with improved time-temperature profiles specifically at the top layer which results in increase of phase fraction of Silico ferrites of calcium and aluminum (SFCA-I). However, beyond 9 vol.% oxygen enrichment, change in sinter properties was not significant. It is considered that excessive increase of oxygen enrichment does not contribute much to the increase of top layer peak temperature.
