Alternative to deal with high level of fine materials in iron ore sintering process

Nowadays, as the demand for iron ore increases together with the depletion of high grade ore deposits, mining companies have been investing to produce iron ore concentrates, such as pellet feeds (95% lower than 0.15 mm) with low level of contaminants. It is well-known that its lower particle size negatively affects the permeability of the sintering process, restricting its use to small quantities. In this way, this work was focused on the use of this fine material in sintering process by replacing regular sinter feeds. The pellet feed was prepared in roller press aiming different levels of specific surface. The iron ore mixtures were evaluated in a regular preparation route composed by two drums, one for mixing and another for granulating. To carry out this study, 25% of pellet feed was added to the mix replacing sinter feeds. The mixtures were tested in pilot sintering pot test under process conditions close to the industrial practice. The results obtained in pot test showed that the previous mechanical treatment of pellet feed is suitable to enable the use of this fine material in sintering process. It was possible to obtain an optimum performance in the granulation step, promoting good process permeability conditions without causing any significant metallurgical or strength demerit in sinter product. The productivity increased from 25.8 t/day/m2 to 29.4 t/day/m2 by adding raw pellet feed and treated by roller press, respectively. Additionally, solid fuel decreased from 69.3 kg/t to 65.9 kg/t, respectively.