Improving energy efficiency in iron ore sintering through segregation: a theoretical investigation

In iron ore sintering, effective segregation of the particulate bed on the strand can result in productivity increases and decreased fuel rate. To find the optimum level of segregation for a given blend, intensive experimental work will be necessary to assess the impact of different segregation levels. The impact of segregation on sintering performance can also be quantified using mathematical modelling. In this work, a well-validated sintering mathematical model has been developed and the effects of mean granule size, bed voidage, bed bulk density, coke mass segregation as well as increased bed permeability on the sintering performance have been investigated. It was concluded that the variation in coke mass down the bed and increased bed permeability are the major factors giving increased sinter yield and productivity in segregated beds. Coke mass segregation has a large impact on maximum bed temperature, residence time above the critical temperature and, consequently, the total heat available to the bed at the critical melt formation period. The effect of variations in granule size and bulk density, caused by segregation, on coke combustion efficiency and bed temperature is small. Bed permeability has the largest impact on flame front speed and, therefore, sinter productivity. Based on differences in bottom and top bed temperatures, the optimal coke mass segregation level was identified. Results from this study provide useful guidelines on optimal segregation level to maintain sintering performance and reduce energy consumption and therefore ironmaking costs