Potencial da lama da dragagem do Porto de Rio Grande, RS, na obtenção de cerâmica isolante térmica

Abstract

The present work evaluated the potential of obtaining thermal insulating ceramics from the mud extracted from the dredging of the access channel to the port of Rio Grande/RS, considering its clayey characteristics and possibilities of incorporation into ceramic masses. The periodic maintenance of the draft in the access channel to the Port of Rio Grande, RS removes large volumes of sediments, which have been traditionally discarded, reaching 49.5 million m3 of dredged material between 1998 and 2020, estimated if the disposal of 2.6 million tons of sediments only in the dredging of 2019-2020, indicating clay contents above 50% in the dredged material, with new dredging in the contracting process 2022/2023 describing the removal of 2 million meters cubic. Clay soils are base materials in ceramic manufacturing, which uses raw materials of a heterogeneous nature, allowing the introduction of residues in their compositions, which leads to reductions in the extraction of new raw materials, allowing the attribution of properties such as plasticity control and addition of porosity, the latter, standing out as an important characteristic in insulating ceramics. To carry out this research, the following raw materials were used: dredging mud, red clay and wood sawdust, which were characterized by X-ray fluorescence tests, granulometric distribution, plasticity and liquidity limits, ray diffraction. X, TG and DTA. Seven formulations formed by pressing at 20MPa, 8% humidity and fired at a maximum temperature of 900°C were studied. For the ceramics produced, linear shrinkage, water absorption, porosity, mechanical resistance to bending at three points and thermal conductivity were determined, also performing microstructural analysis. The data obtained were compared through technical standards with parameters required for ceramic materials or thermal insulators, in addition to a commercial thermal insulator. It can be observed that the dredging mud has granulometric, plastic, chemical, mineralogical and thermal characteristics like the traditional raw material used in the production of red ceramic. In the characterization of the ceramics produced with the seven formulations, it is possible to observe in all proposals the compliance with the parameters of water absorption by NBR 15270 and mechanical resistance, both by technical regulations of other insulating materials, and in comparison, to commercial insulators. A higher porosity was also observed in the formulations that contained the mud, and an increase in porosity in the samples that contained wood sawdust, being identified in these samples the highest percentages of linear shrinkage and loss on fire. For thermal conductivity, no significant difference was identified between the commercial insulator and the studied formulations, obtaining for these a thermal conductivity lower than 0.26W/mK at the analyzed temperatures (25°C and 57°C), demonstrating the ability of the use of dredging mud in the production of thermal insulating ceramics.