Stability of Large Thickened, Non-Segregated Tailings Slopes

Li, Allen; Been, K.; Ritchie, Dwight Dameron; E, Welch, Donald

doi:10.36487/acg_repo/963_34

Cited by 15 publications

(15 citation statements)

References 11 publications

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“…The angle of repose of discharged tailings, also referred as the beach slope (Li et al, 2009), depends on a number of factors including but not limited to:…”

Section: Deposition Beach Slopesmentioning

confidence: 99%

Paste deposition over an existing subaqueous slurry deposit of high sulphide content tailings – the Neves Corvo experience

Lopes¹,

Bahia²,

Jefferies³

et al. 2013

Proceedings of the 16th International Seminar on Paste and Thickened Tailings

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Neves Corvo is a world-class underground copper-zinc mine located in the south of Portugal. The mine has been in operation since 1988 by Somincor (Sociedade Mineira de Neves-Corvo SA), a wholly-owned subsidiary of Lundin Mining Corporation from Canada. The pyritic tailings produced have a very high acid generation potential and until 2010 had been placed subaqueously in the Barragem Cerro do Lobo (BCL), a large tailings pond (190 ha) created by a rockfill dam, 42 m high, across a natural water course. That disposal system provided safe and reliable storage of the reactive tailings. However, by 2001 Somincor realised that the remaining subaqueous deposition capacity was limited and that an alternative site or other deposition methods would be required at this site. Following nine years of studies and evaluation of various alternatives Somincor decided to extend the life of the existing facility, by switching in late 2010 to using subaerial paste/thickened tailings deposition over the existing subaqueous slurry deposit. This approach provides the required storage volume for Somincor's 2005 Life of Mine Plan, and allows maintaining the existing perimeter dam at its current elevation, and facilitates site closure. This paper presents the results of the first two years of operation of the paste production plant and depositional performance of the first two to four metres of paste/thickened tailings over the very loose subaqueous deposit. Routine monitoring data reported includes records of produced paste/thickened tailings densities, yield stress, particle size distribution (PSD), and average specific gravity (SG) of solids. Settlement, deposition beach slopes and piezometric levels in the paste and underlying subaqueous deposit are also routinely monitored. In addition, in 2012 a campaign of Cone Penetration Test Undrained (CPTu) testing and collection of piston samples was carried out to provide in situ strength and permeability data as well as evaluation of the state parameter of the deposited tailings. The 2012 CPTu data is being used for ongoing assessment of the dynamic stability of planned deposition for the next two years. This type of data and a planned special laboratory testing program will be used to calibrate a model of the evolution of the void ratio of the deposit as a function of time and of additional deposition loads. This model will guide the design of the final deposition landform. The environmental component of the deposition monitoring program includes the monitoring of the pH profile of the top one metre of tailings left exposed and allowed to dry as a result of the sequential rotation of tailings discharge.

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“…The angle of repose of discharged tailings, also referred as the beach slope (Li et al, 2009), depends on a number of factors including but not limited to:…”

Section: Deposition Beach Slopesmentioning

confidence: 99%

Paste deposition over an existing subaqueous slurry deposit of high sulphide content tailings – the Neves Corvo experience

Lopes¹,

Bahia²,

Jefferies³

et al. 2013

Proceedings of the 16th International Seminar on Paste and Thickened Tailings

View full text Add to dashboard Cite

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“…The void ratio achieved during the early stage of tailings deposition is one of the key parameters that dictates the in situ tailings properties and the stability of the tailings deposits under long-term conditions. A geotechnical modelling approach is proposed to estimate the void ratio of tailings during thin layer deposition of tailings based on the design method developed by Li et al (2009).…”

Section: Discussionmentioning

confidence: 99%

“…This paper addresses the volume change during the first two phases. The volume change during the third phase is addressed elsewhere (Li et al, 2009).…”

Section: Tailings Deposition and Design Considerationsmentioning

confidence: 99%

“…https://papers.acg.uwa.edu.au/p/1263_03_Li/ Thickened tailings facilities to store over one billion tonnes of tailings have been designed for mining projects in South America, with the heights of the tailings deposits up to several hundred metres (Li et al, 2009). The seismic stability and liquefaction resistance of the tailings is one of the primary design considerations.…”

Section: Introductionmentioning

confidence: 99%

“…The seismic stability and liquefaction resistance of the tailings is one of the primary design considerations. Li et al (2009) developed a design approach for the stability of thickened tailings deposits based on critical state soil mechanics theory. The proposed design approach stipulates that the required density of tailings (or its 'initial' void ratio) be achieved through consolidation and drying prior to deposition of a new layer on the tailings beach.…”

Section: Introductionmentioning

confidence: 99%

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Tailings initial consolidation and evaporative drying after deposition

Li¹,

Been²,

Wislesky³

et al. 2012

Proceedings of the 15th International Seminar on Paste and Thickened Tailings

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Tailings and mine waste management has an ever-growing importance in mining, including the oil sands industry. Dewatering technologies are being adopted and further developed to reduce the environmental and social impacts of tailings management facilities as well as the risks associated with possible failure of dams that retain liquid or liquefiable tailings. The geotechnical performance of tailings deposits is one of the key issues that needs to be fully addressed for large mining projects, including oil sands projects. It has been demonstrated (Li et al., 2009) that the initial void ratio of tailings immediately following deposition is a critical parameter that affects the performance of tailings deposits under both static and seismic loading conditions, particularly the post-liquefaction stability of tailings deposits. This paper presents a design method that draws upon geotechnical modelling techniques to predict the initial void ratio of tailings following self-weight consolidation and evaporative drying achieved through thin layer deposition. The self-weight consolidation model is based on a large strain consolidation theory (Gibson et al., 1967). For evaporative drying, the governing equation is based on a desiccation model (Gilliland and Sherwood, 1933) established for moisture migration within fine-grained soils due to evaporative drying, but the method also incorporates the soil-water characteristic curve equation (Fredlund and Xing, 1994). Analytical solutions have been derived for the governing equations. The modelling tools developed and presented in this paper provide a means to estimate an optimum layer thickness and drying period to increase in situ density of tailings and reduce the liquefaction potential of tailings deposits.

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Instrumentation of Underground Backfill and Surface Disposal

Ahmed

Moghaddam

2017

Paste Tailings Management

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Stability of Large Thickened, Non-Segregated Tailings Slopes

Cited by 15 publications

References 11 publications

Paste deposition over an existing subaqueous slurry deposit of high sulphide content tailings – the Neves Corvo experience

Paste deposition over an existing subaqueous slurry deposit of high sulphide content tailings – the Neves Corvo experience

Tailings initial consolidation and evaporative drying after deposition

Instrumentation of Underground Backfill and Surface Disposal

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