Influência do lodo de estação de tratamento de água nas propriedades mecânicas e termomecânicas de cerâmicas refratárias fabricadas com cinza da casca de arroz

Abstract

The state of Rio Grande do Sul, located in the south of Brazil, is responsible for 70% of the national rice production. Rice husk, with high calorific potential, is a by-product from rice processing and it is often used in to generate electricity. The ash from the burning is rich in silica. In order to have the rice cycle with zero residues, the development of applications for rice husk ash is extremely important. In this context, in the production of silica-aluminous refractory ceramics, the Sludge from a Water Treatment Station becomes a potential source of alumina since it has high amounts of aluminum hydroxide in its composition. The presente research aims to use Rice Husk Ash as a source of silica and Sludge from water treatment as a source of alumina ion order to production of silica-aluminous ceramics and to evaluate their physical, mechanical and thermomechanical properties. The specimens were manufactured with the partial replacement of Kaolin Clay by ash from the burning of Rice Husk in the percentage of 15% by mass and by Sludge from Water Treatment Station in the percentages of 5, 10 or 15% by mass. The ceramics were pressed at 42,5 MPa and sintered at a temperature of 1300 ºC. Physical tests of linear burning shrinkage, mass variation, apparent porosity, water absorption and apparent mass density were performed. The mechanical properties were evaluated through the three-point flexural test and the compression test. The thermomechanical performance was evaluated by the thermal shock test. The addition of Rice Husk Ash and Sludge from Water Treatment Station resulted in higher evidence of Mullite and Cristobalite peaks after burning the samples. The formulation with substitutions of 15% of Rice Husk Ash and 10% of Sludge from Water Treatment Station was the one that presented the best performances in relation to physical, mechanical and mainly thermomechanical properties.