Viana da Fonseca, A & Delgado, BG 2026, 'Improving the sustainability of tailings disposal through better practices in filtered tailings stacks', in AB Fourie, M Horta, M Oliveira & S Wilson (eds), Paste 2026: Proceedings of the 28th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 1-20, https://doi.org/10.36487/ACG_repo/2655_0.02
(https://papers.acg.uwa.edu.au/p/2655_0.02_Viana_da_Fonseca/)
Abstract: Filtered tailings stacks are increasingly considered as a preferable option for tailings storage facilities, as they can enhance stability and structural integrity, thereby reducing the risk of catastrophic failures. This technique involves compacting unsaturated tailings, requiring less disposal area, reducing the risk of groundwater contamination, and allows water recovery from the processing cycle, making it a more sustainable solution with lower environmental impact. This is particularly important in countries with a humid climate (like Brazil) and high tailings production volumes, which distinguish them from international cases. Topics related to particle breakage, transitional behaviour, and the effects of under-compacted materials on static liquefaction vulnerability in iron ore and rare earth tailings are addressed. Mechanical and morphological characterisation of iron ore tailings originating from the Iron Quadrangle region in Minas Gerais, Brazil, are discussed. The mechanical behaviour has been assessed through consolidated undrained (CIU) and consolidated drained (CID) triaxial tests, performed on specimens moulded under varying compaction conditions, including moisture content, compaction degree, and energy application method. The results interpreted under the framework of critical state soil mechanics, when compared with particle morphology data, allowed the evaluation of how grain size distribution and particle shape influence mechanical behaviour. Additionally, the effects of moisture content and compaction energy application method on strength parameters and the determination of the critical state line have been studied. An evaluation of how the grading can affect the compaction characteristics, particle arrangements and overall strength and stiffness of anthropic mixtures of diverse ore tailings, and the importance of the changing of morphological and mineralogical with the increasing of fines content is addressed. A comprehensive characterisation of the mechanical behaviour of these tailings indicates a relevant influence of these factors on their overall performance.

Keywords: mine tailings disposal, compacted filtered tailings stacks, particles size distribution, mineralogy and morphology analysis, fabric, compaction methods, critical state line, instability and softening