Simulação numérica das poropressões em aterros construídos com resíduo da produção de alumina desaguado por filtros prensa

Abstract

The increasing mineral demand observed in the last decades has been responsible for considerable tailings generation. The raising in tailings generation, as well as the lack of areas available for disposal, have pointed out the need for more efficient technologies that render less operational and environmental risks during tailings management. In order to reduce the water in the effluent discharged by the tailings systems, it has been discussed disposal solutions where the disposed material presents higher solids contents, such as paste disposal and filtering processes, for instance. In this research it is presented an assessment of the constructive pore pressures developed in a fill constructed with dewatered red mud from press filter. In order to achieve this goal, geotechnical parameters obtained from laboratory tests performed on red mud samples have been considered, as well as the procedures regarding a numerical modeling application. A test fill located in north of Brazil provided monitoring data to be used in calibrating the numerical model. The software developed by GEOSTUDIO version 2019 R2, SEEP/W, SIGMA/W and SLOPE/W have been used in the construction of the model, based on the Finite Element Method (FEM), which simulates the construction of a fill in stages by coupled analysis of flux and consolidation. The model had been applied to a hypothetical pile in order to assess its stability considering the constructive pore pressure using different values of moisture and compaction conditions, velocity of construction and the pore pressure dissipation over the time while an intern drainage system is implemented. As a result, it was evidenced the applicability of the methodology of estimating the constructive pore pressure developed on dewatered red mud fills. Based on the presented analyses, it was observed the relation between the pore pressure and the moisture content, as well as the corresponding stability, shown as Factor of Safety, related to the external shell, constructed with “dry” residue. Nonetheless, it was pointed out the necessity of an internal a drainage system to dissipate excess pore pressures developed in the fill during construction.