EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

Altering qualities of raw materials for iron making demand changing treatment before using them in metallurgical aggregates. The conventional iron ore sintering process is only suitable for materials down to a particle size of about 0.2 mm. Currently, it is possible to achieve a maximum fine ore amount of up to 180 to 200 kg/t sinter. In this study, the influence of ultra-fine iron ores (< 0.1 mm) on the permeability of the sinter mixture was investigated with its amount up to 500 kg/t sinter. The sinter mixtures were first mixed and then granulated with an Eirich intensive mixer with different mixing tool velocities and loadings for these two steps. The used mixture contains two sinter feed ores and one iron ore concentrate, fluxes, coke breeze as fuel and return fines. The particle size distribution was investigated by conventional sieving methods. Additionally, the particle size distribution of the granulated agglomerates after drying has also been measured. It was found that an increasing content of ultra-fine ores resulted in a mixture with smaller agglomerates. Also, the bigger particles in the mixtures with lower ultra-fines content were able to adhere a bigger amount of the smaller particles. Permeability tests were performed in a lab rig in which the pressure drop of a bed with a constant volume flow of air have been measured. The results showed a decreasing bed permeability with increasing ultra-fine ore rate at constant water content.