Sensitivity analysis of tailings disposal and drying cycles in a bauxite tailings dam

This study aims to evaluate opportunities for improvement in the disposal and drying cycles adopted in the operation of a storage reservoir for thickened tailings from bauxite processing that is part of a project located in the northern region of Brazil. The reservoir is divided into quadrants and, currently, the disposal occurs in 0.5 m-thick sequential discharge layers of tailings, with approximately 34% solids content by weight (SC). In the routine operation of the structure the subsequent layer is released when the lower layer reaches an SC of around 60%. After occupying the useful volume of the quadrant, mechanical excavation of the disposed dry tailings is carried out. This is directed towards the closure of the mining areas of the project, freeing up space for a new cycle of operation at the structure. The work proposes a sensitivity analysis of the expected drying curve through analytical equations and the assistance of numerical tools for evaluation of consolidation and drying. Fifteen combined variations will be performed, including different SC (between 30% and 38%) and five different layer thicknesses. Such analyses will make it possible to understand the drying times necessary to obtain the minimum SC for mechanical excavation and, consequently, will allow an evaluation of the complete operating cycle of the reservoir.