Influence of the mineralogical composition of binders on the strength of sinter

Abstract

The formation of ferrosilicate melt in hightemper� ature sintering zones is responsible for the strengthen� ing of the ironore batch and its conversion to pellets or briquets. The melt is formed from the silicon and calcium components of the batch, the solidphase reaction products in the heating zone, and, to some extent, from the small ore fraction of the concentrate. When the solidand liquidphase reactions are com� plete, the cooled sinter is converted to a twophase mineral system consisting of ore phases (magnetite Fe3O4 and hematite Fe2O3) and silicate-ferrite bind� ers. Their composition is determined by the batch basicity (CaO/SiO2), while their microstructure depends on the sintering parameters and the cooling of the product. The mineralogical composition of the sinters and the thermal properties of the oregrain binders deter� mine the strength of the final product and its behavior on reduction in the blast furnace (1-5). Several researchers have studied the influence of the sinter's mineral composition on its strength. In comparing the strength of ironore sinter of the same basicity produced from ore concentrates of different origin, we find, for example, that the strength of the sinter is lowest at low basicity (0.7-1.5). As the basic� ity rises 2.0, the strength gradually rises (6). Decrease in sinter strength is may be attributed to the multiphase structure of the silicate binders with different physico� mechanical properties, while increase in strength is associated with the appearance of ferrite phase in highbasicity sinters, according to (6). However, we still do not know why the direction of mineral formation of the sinter binders changes with increase in flux content of the ironore batch over a broad range of sinter basicity, even with increase in the fuel content. The binder composition for magnetite grains varies from ironsilicate form, when the melt� forming component is divalent iron CaFeSiO