Influência do lodo de estação de tratamento de água e da cinza da casca de arroz para aprimorar as propriedades mecânicas e termomecânicas de materiais cerâmicos

Abstract

Green engineering advocates the use of waste from a given process as raw material for the manufacture of new products, so that this activity results in zero waste. In rice production, the straw resulting from the harvest is used in the crop itself as fertilizer and soil cover to avoid soil exposure and promote an increase in organic matter. Rice processing has the husk as its main residue, which has been used as a source of thermal energy for the generation of electricity. Burning the husk results in rice husk ash (RCA), which is rich in silica when burned at controlled temperatures and, therefore, can be used as a raw material for the manufacture of glass, polymers and ceramics, among others. Similarly, water treatment plants (WTP) have WTP sludge as their main waste, which is usually rich in aluminum due to the chemicals used in the water purification process. In this way, RHA and ETA sludge can be used as a source of silica and aluminum, respectively, for the manufacture of silico-aluminous refractory ceramics, which is the purpose of this work. The main objective of this work is to improve the mechanical and thermomechanical properties of refractory ceramic materials, reducing production costs and environmental impacts in order to contribute to regional development. Ceramic specimens were manufactured using kaolin clay with 10% replacement of CCA and 5, 10 and 15% ETA sludge by mass. Physical properties (apparent porosity, water absorption and mass density), mechanical properties (tensile strength in three-point bending and compressive strength) were evaluated, as well as thermomechanical properties (resistance to thermal shock). In addition, the microstructures of the specimens were analyzed through the microstructural analysis test in SEM and X-ray diffraction. The refractory ceramic composed only of kaolin clay showed the best result in the tensile strength tests. In the compressive strength test, the refractory ceramics with the addition of 10% CCA showed a reduction of approximately 40% compared to the sample with 100% CA. In the thermal shock test, the ceramics composed with ETA sludge showed an improvement in resistance to thermal shock compared to the 10 CCA composition.