Avaliação de fonte alternativa de MgO na mistura de sinterização de minério de ferro

The sinter is a porous agglomerate of iron ore, produced from the mixture of fine iron ore, fluxes and fuels and additives. It is notorious that the increase in sinter return is directly linked to the decrease in the mechanical resistance of the sinter product, and with this the low yield of the mixture, on the other hand the magnesian ore has properties that are impactful to minimize this effect on the production of sinter. The source of MgO used in the intermissions comes from dolomite. When subjected to the sintering process, dolomite is decomposed, releasing magnesium oxide (MgO). MgO acts as a modifier of the properties of the slag, improving its fluidity, viscosity and capacity to absorb impurities, in the reduction process in the blast furnaces. The objective of this study was to evaluate the use of magnesian ore as a source of MgO in the sintering process and its impacts on the process, such as the mechanical strength of the produced inter, and the yield of the mixture to be sintered, degradation index under reduction and reducibility index. For the addition of 20 kg of magnesian ore (total replacement of the MgO source) for the production of 1 ton of sinter, there was an increase of 2.6 p.p. in the degradation index under reduction, a reduction of 2.3 kg/t of sinter produced in fuel consumption, a reduction of 67.94 kg/t of sinter in the generation of return sinter. The yield of the total mixture showed an increase of 2.59 p.p., compared to the 100% dolomite; without significant impacts that impair the quality of the sinter. Therefore, the substitution of the MgO source from dolomite to magnesian ore proved feasible. Keywords: Dolomite. Magnesian ore. Sinter. Mechanical strength of the sinter.