Secagem e queima de placas cerâmicas cm adição de rejeito de diatomita: caracterização e simulação.

Abstract

Red ceramic has a high potential for use in the most diverse areas of civil construction and its properties can be improved through the use of alternative materials by substitution or addition to clay. The final products are mostly of low quality, due to inadequate processes. Within this context, this work aims to evaluate the results of the drying and firing processes of ceramic slabs with the addition of diatomite waste in their composition, performing thermogravimetric, physical, chemical, mechanical characterization and computer simulation. Ceramic plates with dimensions of 60x20x5 mm were made, with addition of waste at levels of (10, 20 and 30%) in clay mass with homogenization times of (30, 45 and 60 min). The thesis presents experimental results of slabs submitted to drying in ovens at different temperatures (60, 80 and 110oC), after

which the slabs were fired at temperatures of 800, 900 and 1000oC, and then the physical- mechanical properties were determined. From the data obtained, computer simulations were

carried out with the concentrated, distributed and CFD models. From the experimental results, it was found that the best composition for the physical-mechanical properties was 10% waste with a homogenization time of 30 min and a firing temperature of 800 °C. About the theoretical results of the drying process of ceramic slabs, it was concluded that temperature is the main parameter that controls the removal of moisture from the material. It was observed that the diatomite tailings decrease the water retention in the plates, with the best results found for the mixtures with 30% tailings. However, the inverse was verified for the homogenization time, with a tendency of greater water retention for longer times. The drying curves constructed from the kinetics curves showed good agreement with the experimental data, being validated within a 99% confidence interval. The Laplacian model of heat and moisture transfer, as well as the boundary conditions used, were able to predict the phenomenon of drying and heating of ceramic slabs.