Caracterização e avaliação da atividade pozolânica das cinzas provenientes da queima de carvão mineral das termelétricas do Pecém, Ceará, Brasil

Abstract

The trend towards stabilization of coal consumption, observed until 2019, was interrupted due to the Sars-Cov 2 pandemic that affected energy production based on mineral coal, reducing the world demand for this product. The burning of mineral coal for energy production in thermal power plants generates large amounts of waste, such as light ash (fly ash), from electrostatic processes and background ash (botton ash), from desulfurization processes of the chimney gas (Flue Gas Desulfurization - FGD). In many residues, they are stored in open air deposits, becoming a potential risk to the environment and the surrounding ecosystems. In order to improve understanding of the characteristics of these residues, we sought to characterize light ash (CV1) and bottom ash (CV2), residues from the Pecém I and II thermoelectric plants, located in the state of Ceará / Brazil, regarding chemical and physical parameters by means of chemical composition tests by FRX (X-Ray Fluorescence) and EDS (Dispersive Energy Spectroscopy), moisture content, loss to fire, insoluble residue content, specific mass, fineness by air permeability method, granulometric characterization, microstructure evaluation by SEM (Scanning Electron Microscopy), thermogravimentation, determination of the mineralogy phases by XRD (X-Ray Diffraction) and evaluation of pozzolanic activity. It was evidenced that CV1 has characteristics compatible with type C fly ash and pozzolanic activity. For CV2 ash, it was observed that the chemical requirements for pozzolanic activity were not met, also presenting high levels of sulfur trioxide and crystalline phases such as Calcite, from the FGD desulfurization process. In both cases, the ashes can be used in cementitious compounds, as long as they are compatible with the characteristics presented, thus enabling the reduction and accumulation of material in the plants, reducing the risks to the environment.