Avaliação do desgaste de massa de tamponamento via simulação termodinâmica e comparação com ensaio de corrosão dinâmico

Abstract

The opening and closing of the tap hole during the production of pig iron in steel-making industries is crucial for the proper operation of the blast furnace and high production in the steel industry. The tap hole clay is the material used for this purpose and it acts : (i) closing the hole after the removal of liquids from the furnace, (ii) allowing the opening of the equipment, when it is necessary to drain the liquids again, and (iii) lining the inside of the blast furnace to protect the crucible. The hot face of this refractory mass has contact with slag and pig iron at temperatures above 1200°C, where the chemical composition of these liquids can lead to interactions that corrode/wear the ceramic, leaving the crucible wall exposed, which is one of the regions of the blast furnace that must be preserved due to its difficult maintenance. In this context, the understanding of the interactions that lead to the wear of the refractory mass is of great importance so that new formulations can be made. Thus, the objective of this work was to analyze and compare the behavior of a reference tap hole clay with others that contain the addition of MgO, TiO2 or Fe2O3 (in similar amounts) when in contact with a blast furnace slag. In this sense, thermodynamic simulations were performed via FactSage and corrosion tests were carried out in the laboratory, as the former considers that thermodynamic equilibrium was reached, and in practice, the contact of the material with the liquid is made for only a few hours, and this period may not be enough for all possible reactions to take place. Based on the studied compositions, the addition of TiO2 or Fe2O3 to the formulation resulted in similar behavior when compared to the reference composition, in both cases, the simulation and corrosion tests. On the other hand, the MgO incorporation to the mixture led to a greater number of calculation steps for the refractory stabilization in the simulation, and this trend was also observed in the experimental measurements, resulting in greater wearing of this tap role clay. It was also verified that the slag composition variation in the theoretical calculations was similar to the one found in the lab tests, indicating that, despite not quantifying the extent of wearing, thermodynamic simulation is valid for comparison and selection of formulations regarding their performance when in contact with reactive slag at high temperatures.