| The cohesive zone in the blast furnace, where ferrous burden materials soften and melt, greatly affects its performance. Minimizing the size and lowering the position of the cohesive zone will improve productivity and decrease the coke rate. This work was designed to better understand the softening and melting phenomena of ferrous feed materials. Different experimental techniques were used to allow the observation of different stages of softening and melting. Three pellets were used: Acid, Basic Fluxed (with dolomite) and Olivine Fluxed pellets.; The experiments performed in the Confocal Scanning Laser Microscope (CSLM) were designed to measure the temperature where liquid was first formed, as well as the evolution of its fraction. Also, by interrupting these experiments at different temperatures, it was possible to observe the changes in the microstructure with temperature. By using two different heating rates, it was possible to observe the effect of the residence time in the dissolution of particles in the early stages of melting. The three types of pellets used in this series of experiments were pre-reduced to wustite.; To observe the interaction between the pellets at high temperatures under load, experiments were performed in a resistance furnace with X-ray imaging equipment. The pellets were pre-reduced to 60% or 80% reduction degree (oxide basis), placed in a graphite crucible and heated under N2 gas flow. Besides the pictures, the displacement and temperature were also recorded. In this series, experiments were performed with individual pellets as well as with a mixed burden of Fluxed with Acid pellets at a ratio of 2:1.; The analysis of the interaction at the macrostructural and microstructural level was possible with samples obtained in experiments performed under load in an inductively heated furnace, which were interrupted at a specific point.; A computer slag model was used to estimate the effect of different elements on the melt onset at the slag-wustite interface. For this, CaO-SiO2-FeO isothermal sections at different temperatures, with and without the addition of MgO, Al2O3 and Na2O, at different content and permutations, were calculated. This model was also used to calculate pseudo-binary sections of FeO with different flux materials or gangue particles, with and without Na2O, in order to estimate the melting or dissolution behavior of these particles. Finally, this model was used to calculate the evolution of the liquid mass fraction with temperature. (Abstract shortened by UMI.)... |
