Análise de liberação de gás e queda do Índice de plasticidade de uma massa refratária moldável

Abstract

During the vertiginous growth of the monolithic moldable refractories market in the past decades, the use of Al2O3–SiO2–SiC–C refractories has been highlighted in blast furnace casting systems. Within this classification, the Ramming Mix, a monolithic mass that has the main function of making small repairs in foundry spine sticks, is manufactured by SAINT-GOBAIN Performance Ceramics Refractories and presented quality deviations due to gas release and abrupt drop in the Plasticity Index of the material in a short period of time. The study aimed to investigate the possible causes of quality deviations in the Ramming Mix mass and list potential solutions to the problem. The total amount of magnesium oxide in the mass is listed as a possible cause of the deviation due to its high reactivity with water and in the workability of the mass. Thus, the plasticity and humidity parameters of approved and disapproved masses were analyzed and the results were compared with the manual addition of different amounts of MgO in an approved mass. It is possible to verify that the higher the addition of oxide, the lower the Plasticity Index of the mass, and, in relation to humidity, there were no significant variations of the parameter with the addition of MgO. As a solution to the problem, it is proposed that the parameters specification of quality ad being changed.