A numerical modelling approach to assess long-term unsaturated flow and geochemical transport in a waste rock pile

Fala, O.; Molson, John; Aubertin, Michel; Dawood, Ihssan; Bussière, Bruno; Chapuis, Robert P.

doi:10.1080/17480930.2011.644473

Cited by 31 publications

(19 citation statements)

References 22 publications

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“…Numerical simulations with stochastically distributed material properties were used to study unsaturated water flow and geochemical transport in sulfidic waste rock piles (Fala et al, 2013). Used in the simulations were the water retention curve and hydraulic conductivity function as spatial variability for water flow, and distributed geochemical parameters as reactive transport.…”

Section: Modeling and Simulationmentioning

confidence: 99%

Mine Drainage: Characterization, Treatment, Modeling, and Environmental Aspect

Wei

Wolfe

Han

2014

Water Environment Research

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Globally, mine drainage is a persistent environmental problem facing the mining industry. This review covers the literature published in 2013 on topics relating to acid mine drainage (AMD) or acid rock drainage (ARD) due to the presence of sulfide bearing minerals in active and abandoned coal/hard rock mining sites or waste spoil piles. This review is divided into the four sections: 1) mine drainage characterization, 2) mine drainage treatment 3) modeling and simulation, and 4) environmental aspect. Mine Drainage Characterization Physicochemical Characterization. The characteristics of mine sites have profound impacts on the quality and quantity of acid mine drainage (AMD) or acid rock drainage (ARD), the toxicity of the contaminants, the fate and transport of the metals, and the required treatment or remediation methods. The mine drainage from the Globe-Progress gold mine, New Zealand, were circumneutral (pH 6-8) with high HCO 3 -and SO 4 2-(both up to 300 mg/L) and elevated As (0.5 mg/L) and Sb(~3 mg/L) (Druzbicka and Craw, 2013). The Sb/As ratio in the mine drainage ranged from 1 in historic mines, to ~30 below the modern mine. It was found mining methods and contrasting ore types had a dramatic effect on the metalloid contents. The characteristics of alkaline mine drainage from 11 active and abandoned mines were examined in the Lokpaukwu-Ishiagu mining areas of Nigeria, where very high concentrations of TDS, hardness, chloride, calcium,

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Section: Modeling and Simulationmentioning

confidence: 99%

Mine Drainage: Characterization, Treatment, Modeling, and Environmental Aspect

Wei

Wolfe

Han

2014

Water Environment Research

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“…Furthermore, typical laboratory-based methods (such as humidity-cells) or field-cell experiments do not capture additional structural features such as fining upwards or traffic surfaces (characterized by smaller grain size and lower porosity due to compaction from heavy equipment driving along exposed weathering surfaces during the construction process). To this end, numerical models have proven suitable tools for investigating the influence of physical and chemical heterogeneities (Molson et al, 2005;Fala et al, 2013;Lahmira et al, 2017;Pedretti et al, 2017;Appels et al, 2018;Muniruzzaman and Pedretti, 2020), as well as scale (Wilson et al, 2018;Vriens et al, 2020b) on ARD generation and attenuation processes in WRPs. However, at the time of writing a sensitivity analysis that examines the roles of physical and chemical parameter distribution, with a particular emphasis on the effect of pile construction methods, structural features, and pile scale, has not been completed.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Influence of Structure and Heterogeneity in Waste Rock Piles on Mass Loading Rates—A Reactive Transport Modeling Study

Raymond

Seigneur

et al. 2021

Front. Water

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Placement methods and material availability during waste rock pile (WRP) construction may create significant heterogeneities in physical and geochemical parameters (such as grain size, permeability, mineralogy, and reactivity) and influence the internal pile structure. Due to the enormous scale of WRPs, it is difficult to capture the influence of heterogeneities on mine drainage composition and evolution. Although laboratory- or field-scale experimental studies have provided much insight, it is often challenging to translate these results to full scale WRPs. This study uses a numerical modeling approach to investigate the influence of physical and chemical heterogeneities, structure, and scale on the release of acid rock drainage (ARD) through 2D reactive transport simulations. Specifically, the sensitivity of drainage quality to parameters including grain size distribution, sulfide mineral weathering rates, abundance and distribution of primary minerals, and pile structure as a function of construction methods are investigated. The geochemical model includes sulfide oxidation, pH buffering by calcite dissolution, and ferrihydrite and gypsum as secondary phases. Simulation results indicate that the implications of heterogeneity and construction method are scale-dependent; when grain size distribution trends observed in a pile's core are applied to the entirety of a pile, results between push- and end-dumping methods vary substantially—however, predicted drainage for different construction methods become more similar when features such as traffic surfaces, structural variation, and multiple benches are also considered. For all scales and construction methods investigated, simulated results demonstrate that pile heterogeneity and structure decrease peak mass loading rates 2 to 3-fold, but cause prolonged ARD release compared to the homogeneous case. These findings have implications for the economics of planning water treatment facilities for life of mine and closure operations.

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“…A detailed discussion of the scaling relationships and their application to the hydraulic properties of a heterogeneous waste rock piles is given by Fala et al (2008Fala et al ( , 2013. The soil heterogeneity in the simulations is included by treating K s as the realization of a spatially randomly distributed field with a specified standard deviation and correlation length.…”

Section: Simulation With Stochastic Propertiesmentioning

confidence: 99%

“…These conditions have created a pseudostationary condition (Fala et al 2005(Fala et al , 2013. The simulation S1 (Fig.…”

Section: Base Casementioning

confidence: 99%

“…Therefore, to accurately simulate flow and transport in rock piles, models must include the variability in soil hydraulic properties. The influence of spatial variability of hydrogeological properties can be assessed by using a stochastic approach (Fala et al 2005(Fala et al , 2013. In this case, it is assumed that the value of a given property at two locations depends on the distance between them; the closer they are, the closer their property values will be (on average).…”

Section: Simulation With Stochastic Propertiesmentioning

confidence: 99%

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Numerical simulation of water flow in a large waste rock pile, Haizhou coal mine, China

Namaghi

Sheng

Liguo

2015

Model. Earth Syst. Environ.

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Waste rock is the large volume of broken rock and low grade ore materials tend to create potential problems, such as acid mine drainage (AMD), leaching of heavy metals, and slope stability problems. These problems are related to the flow of water through the waste rock. In this study, long term numerical simulations of unsaturated flow in a large waste rock pile are conducted to investigate the effect of internal variability in water flow and saturation. The approach first consists of a basic geotechnical properties investigation to define the main features of the pile. This is followed by numerical simulations of the unsaturated flow through the pile based on the results from the field and laboratory characterization. The simulation results showed that pile is unable to fully saturate and drain during the simulated period. It was also found that high evaporation and the high bottom flux rate and also coarse grain nature of waste rock materials results holding few amounts of water in the system.

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A numerical modelling approach to assess long-term unsaturated flow and geochemical transport in a waste rock pile

Cited by 31 publications

References 22 publications

Mine Drainage: Characterization, Treatment, Modeling, and Environmental Aspect

Mine Drainage: Characterization, Treatment, Modeling, and Environmental Aspect

Investigating the Influence of Structure and Heterogeneity in Waste Rock Piles on Mass Loading Rates—A Reactive Transport Modeling Study

Numerical simulation of water flow in a large waste rock pile, Haizhou coal mine, China

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