8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

The iron ore sintering process is essentially influenced by the permeability of the sinter bed. Higher amounts of ultra-fine iron ores lead to a weak granulation behaviour, which causes lower voidage in the sinter bed and therefore a decreasing bed permeability. Due to this, the application of ores with a size lower than 0.2 mm is limited. In this investigation the amount of ultra-fine ores (-0.1 mm) in the sinter mixture is increased stepwise up to 500 kg/t sinter mixture by using an intensive mixer for mixing and granulating and hydrated lime as binder. Trials in a laboratory sinter pot could show that with this method it is possible handle such high amounts of ultra-fines with only a minor loss in productivity and increase of solid fuel. By using about 300 kg ultra-fines per tonne of sinter mixture no negative changes neither in sintering process nor in product yield was observed. The sinter product was investigated regarding its quality. The sinter strength was measured with the shatter test and showed virtually no decrease with increasing amount of ultra-fines in the sinter mixture. The reduction behaviour of sinter produced from the mixture with 500 kg/t ultra-fines was investigated using a Tammann furnace experimental set and thermo-balance facilities. Isothermal tests were conducted to determine the activation energy; non-isothermal tests were performed under conditions simulating the area of the cohesive zone in the blast furnace; results were compared with those for a reference sinter.