Geotechnical-geochemical and operational considerations for the application of dry stacking tailings deposits – state-of-the-art

Montani, Jose Lara; Pornillos, Emmanuel; Munoz, Henry

doi:10.36487/acg_rep/1363_19_munoz

Cited by 11 publications

(3 citation statements)

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“…All the tests were performed on Eleonore filtered tailings with an initial dry density of 1.7 g/cm 3 and an initial gravimetric water content of 16%. A high air-entry ceramic disc with an air-entry value (AEV) of 150 kPa was equipped to control suctions by using the axis translation technique (Hilf 1956). The pore air pressure was applied and adjusted by an air automatic pressure controller (APC) inside a sealed box.…”

Section: Unsaturated Shear Strengthmentioning

confidence: 99%

“…In recent years, developments of tailings dewatering technologies, and especially filtered tailings, have contributed to maximise water recovery and minimise geotechnical risk (Simms 2017(Simms , 2021. The objectives of filtered tailings in particular are to produce tailings with solid content greater than 80% using various dehydration processes (Lara et al 2013;Weatherwax & Kipara 2010). Filtration contributes to create an unsaturated cake that can be stored without requiring large slurry tailings ponds.…”

Section: Introductionmentioning

confidence: 99%

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Effects of low suction and wetting–drying cycles on filtered tailings shear strength

Lê¹,

Pabst²

2023

Paste 2023: 25th International Conference on Paste, Thickened and Filtered Tailings

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Filtered tailings management has many advantages over traditional slurry tailings management, such as improved water recovery and recirculation, and a reduction of geotechnical risk. However, the long-term evolution of the water content in filtered tailings exposed to climatic conditions could affect its geotechnical properties. Shear strength properties of unsaturated tailings have a critical role when evaluating the geotechnical stability of a dry stack facility, especially in the context of climate change. The objective of this research was, therefore to investigate the influence of drying and wetting cycles on the shear strength of filtered tailings for a low matric suction range (i.e. 0~50 kPa). A series of consolidated-drained (CD) direct shear tests were conducted on re-compacted unsaturated filtered tailings specimens. For each matric suction achieved by following either the wetting or drying curve, three direct shear tests were performed with varying normal stresses. Direct shear test results showed a nonlinear increase in the unsaturated shear strength with the normal stress and matric suction. Empirical hyperbolic functions were used to fit experimental data and evaluate the shear strength of unsaturated filtered tailings for a higher matric suction range. Test results also indicated some hysteresis, and the shear strength during drying was smaller than during wetting for the same matric suction. However, matric suction and water retention curve (WRC) hysteresis had no significant impact on the measured effective friction angle.

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Section: Unsaturated Shear Strengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of low suction and wetting–drying cycles on filtered tailings shear strength

Lê¹,

Pabst²

2023

Paste 2023: 25th International Conference on Paste, Thickened and Filtered Tailings

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“…This article shows a design approach that illustrates the impact of stress and porewater pressure variations on the Factor of Safety of the heap throughout the construction period. Related studies include Priscu (1999), Zardari (2011), Martin & McRoberts (1999), and Lara et al (2013).…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of dry stacking tailings heaps

Vizcarra¹

2021

Paste 2021: 24th International Conference on Paste, Thickened and Filtered Tailings

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In the practice of geotechnical engineering applied to mining, dry stacked tailings heap projects are analysed by limit equilibrium methods and stress-strain analyses. These methods and model assumptions do not consider the influence of the partially drained conditions, strain softening, and transition from over-consolidated to normally consolidated behaviour of the foundation. This situation can lead to calculations of deterministic safety factors that are often overestimated, according to the nature of the foundation. This article proposes a methodology for numerical modelling of the foundation during staged construction of a heap, and considers loading time as a critical variable in calculating the Factor of Safety of the heap dry stacked of elaborating a numerical model considering the foundation and construction.The physical and geotechnical properties of the materials were derived through the model, and are the interpretation of data obtained from a geotechnical investigation and laboratory testing campaign. Stress-strain analyses are performed for different stacking speed scenarios to assess its influence on the safety factor at each loading stage. The analyses are coupled, where the distribution of stresses and deformations within the foundation and the dissipation of porewater pressures over time are simulated. The results show the evolution of the Factor of Safety, the spatial distribution of the regions with excess porewater pressure, allowing the optimisation of both the rate of rise of the dry stack and external batter slope for the project to minimise ground improvement.It is observed that there is a strong dependence of the coefficient of permeability of the foundation soils on the porewater pressure dissipation time. Numerical modelling considering partially drained conditions allows greater understanding of foundation behaviour and performance during the development of the dry stacked heap. The analysis is considered applicable to both soft soil foundation conditions and conversion of existing wet disposal tailings facilities to dry stacking atop, referred to as 'piggybacking' within the mining industry.

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