Dry stacked filtered tailings: seepage behaviour during the construction process

Abstract

In the last decade, filtered tailings deposits (FTDs) have become relevant in the mining industry because they reduce physical stability risks due to the low degree of saturation in which they work. This paper focuses on the seepage process during the construction of a conceptual dry tailings stack. The seepage process was analysed with a coupled and uncoupled model in the structural and non-structural zone of a FTD to determine the influence of variables such as density, degree of saturation, permeability, tailings disposal and interaction with the environment (precipitation) inside a dry stack. An FTD is conceptualised with a construction period of approximately 10.8 years and a rainfall regime that presents a wet season that limits the construction periods. The results show that the use of coupled seepage models determines sectors with greater thicknesses and higher degrees of saturation compared to uncoupled models. A comparative analysis is also carried out for the use of raincoats on the structural zone during the wet season. Not using a raincoat allows the generation of layers with a higher degree of saturation, which generates a heterogeneous structural zone that could have an impact on its shear strength. Finally, based on the results, guidelines are provided for geotechnical laboratory investigation plans, the adaptation of field conditions to model boundary conditions and filtered tailings disposal configurations.