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The rhizosphere is an important interface for soil–plant interaction and a significant zone for the uptake and removal of heavy metals from soils. This study assesses the level of heavy metals contamination in the rhizosphere of plants growing at a decommissioned tailings dam in Ghana. Concentrations of heavy metals [Arsenic, Cadmium, Copper, Iron, Manganese and Zinc] and physicochemical parameters [pH, conductivity, total dissolved solids, phosphate, nitrate, sulfate] of rhizospheric soils were determined. The assessment of the extent of rhizospheric contamination was conducted using the enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI). Factor analysis unveiled the most relevant heavy metal contributors to rhizosphere contamination. Results indicate moderate to significant enrichment of Cd (1.72 – 8.28) and Mn (1.70 – 8.32) in the rhizosphere. The PLI showed that rhizospheres are heavily polluted (18.8 – 29.6) and thus require remediation. Principal component analysis revealed significant Cd, As, and Fe contamination in the rhizosphere accrues from anthropogenic or mining activities. The levels of heavy metal ions in the rhizosphere suggest that Mimosa pudica, Centrosema pubescens, Leucaena leucocephala, Pueraria phaseoloides, and Tridax procumbens could be investigated as candidates for phytostabilization of mine tailings. This study emphasizes the importance of effective remediation and continual tailing dam monitoring before and after decommissioning to avert the spread of heavy metal contaminants. [ABSTRACT FROM AUTHOR]

There is carried out a quantitative assessment of the changes in the circulating water composition under the influence of its conditioning method in a circulating water supply system of the Balkhash Concentrator Plant. Research objects are circulating water model mixtures which are reuse in copper ores flotation after clarification in a tailings dam. They are obtained in a laboratory because of modelling the mixing and storage conditions of enrichment tailings from the Balkhash Concentrator Plant and acid effluents neutralization sludge from the Balkhash Copper Smelter Plant with industrial effluents from other enterprises in Balkhash region. There is considers two schemes for conditioning of recycle water in the process water supply system: by mixing clarified water obtained during the combined or separate waste storage (enrichment tailings and acid effluents neutralization sludge). Studies have shown that after mixing these flows in the tail collector and their combined storage in the tailings dam chemical and physico-chemical processes occur that contribute to the removal of several pollutants (copper, arsenic, iron, zinc, cadmium, and nickel) from circulating water, which can be explained by the binding of cations these elements into insoluble compounds. Based on the results obtained, it is recommended to use a combined waste storage technology for the circulating water conditioning. [ABSTRACT FROM AUTHOR]

In this paper, ground deformation measurements from synthetic aperture radar interferometry (InSAR) and ground-based prism monitoring are compared to finite-element (FE) simulation results for a recent tailings dam collapse. The InSAR monitoring demonstrated the complex spatial and temporal variability of the tailings dam deformation that is not captured in traditional, point-based monitoring approaches. Potentially anomalous deformation behaviour could have been detected from InSAR 1 year preceding the dam failure. A two-dimensional coupled-consolidation analysis was used to predict the dam behaviour during construction stages. The FE modelling results were in broad agreement with the deformation measurement sources, both in terms of magnitude and trends preceding failure. The results, however, deviate significantly immediately before failure, following the construction of the buttresses. Moreover, the FE modelling is sensitive to parameter uncertainties, such as spatial variability of foundation soil properties. The FE results revealed that deformation in both the upstream and downstream parts of the dam are sensitive to changing foundation properties. However, this impact is potentially much more significant on the downstream compared to the upstream parts of the dam, which are dominated by the behaviour of the tailings. This study highlights the efficacy and complementarity of geotechnical and remote sensing techniques for the monitoring of tailings dams. [ABSTRACT FROM AUTHOR]

With the increasing frequency of extreme weather events, heavy rainfall and flooding pose significant pressure on the flood discharge systems of tailings dams. Simple discharge systems are insufficient to meet the flood discharge requirements of tailings dams, while complex discharge systems, with their greater flood discharge capacity, are gradually being promoted. Although complex discharge systems can increase the flood discharge capacity of tailings dams, the flow patterns within the discharge systems become more complex. As a new type of discharge system layout, existing research lacks systematic analysis, and its complex flow characteristics are not clear. This paper relies on the flood discharge system of a large tailings dam to carry out theoretical calculations and derivations of the hydraulic characteristics of the complex flood discharge system. Hydraulic characteristics are observed through hydraulic model tests and verified using numerical simulations. Based on these three methods, a basis for further research on the hydraulic characteristics of complex flood discharge systems is provided. The main results are as follows: (1) The formulas for calculating the discharge flow rate Q under different flow states in the tailings dam design manual are not applicable to complex discharge systems; (2) Formulas for calculating the discharge flow rate Q under different flow states in complex discharge systems are proposed; by comparing model test values and numerical simulation values, the accuracy of the formulas for calculating the discharge flow rate Q in complex discharge systems is verified; (3) If the traditional mode is used to calculate the discharge flow rate Q in complex discharge systems, it is recommended to take the reduction coefficient as 0.55–0.56, and the model test values should also be referred to during flow state transitions.

Accurately predicting changes in the infiltration line is crucial for the stability and safety of tailings dams. To fully leverage the spatial features and temporal information provided by infiltration line data, this paper proposes a combined approach using one-dimensional convolutional neural network (1DCNN) and long short-term memory neural network (LSTM) for infiltration line prediction. Taking the main dam of the Qidashan Fengshuigou tailings storage facility in Liaoning Province, China, as an example, the model utilizes six major factors, including historical infiltration lines, reservoir water level, internal and external displacements of the dam, dry beach length, and rainfall, as input data to predict the infiltration line positions for the next 1 day and 3 days. The 1DCNN-LSTM model is compared with classical LSTM and backpropagation neural network (BP) models. The results indicate that the Pearson correlation coefficients (R) for the 1DCNN-LSTM infiltration line predictions are consistently above 0.9. For the next 1 day, the mean absolute error of infiltration line prediction is 0.002 meters, with a maximum absolute error of 0.08 meters. For the next 3 days, the mean absolute error is 0.003 meters, and the maximum absolute error is 0.068 meters. These results demonstrate the superiority of the 1DCNN-LSTM model over classical models, providing a reliable reference for short-term infiltration line predictions. [ABSTRACT FROM AUTHOR]

This work aims to present and discuss a conceptual project of mining tailings dam. Therefore, specific topics on tailings dams are visited and the characterization of materials constituting such structure is reviewed in the literature. Based on parameters available in the literature, a hypothetical dam was schematized and its stability was assessed via computational analysis (limit equilibrium and finite element flow analysis). Assessing eventual design changes (additional dam heightening) and hypothetical situations (collapses in the internal drainage), it is concluded that the schematic conceptual design presents itself viable and stable given the proposed geometry and the properties of materials considered. The importance of the internal drainage system for the dam's stability was also identified. [ABSTRACT FROM AUTHOR]

Scientific calculating of deformation early warning thresholds is of great significance for identifying the abnormal operation state of tailings dams. Traditional early warning studies cannot take into account the fuzziness and randomness of monitoring data, and most of them focus on single-point and single-level early warning, which cannot accurately reflect the operational state and the risk level of failure of the tailings dam. In this study, an early warning model based on cloud theory (CT) and concept hierarchy construction (CHC) is proposed to determine a reliable warning of multi-point displacement of tailings dam. The CT is used to calculate the characteristic values of displacements, including expectation (Ex), entropy (En), and hyper entropy (He), which can eliminate the influence of fuzziness and randomness of the monitoring data. The multi-point characteristic values of displacements are integrated via the CHC method to obtain the characteristic values representing the integral qualitative concept of the tailings dam, which can overcome the limitation of single-point early warning. The normal operation value of displacement of tailings dam is calculated according to the "3En" principle, and the comprehensive early warning displacement thresholds are obtained. The displacement monitoring data of Yangjiawan tailings dam demonstrates the rationality and accuracy of the developed CT–CHC model. Our work provides a new avenue to warn of the potential failure of tailings dams. [ABSTRACT FROM AUTHOR]

The stress-strain state and strength of the cutoff wall in the base layer of a tailings dam is assessed through numerical simulation [ABSTRACT FROM AUTHOR]

Landslides in mining engineering mainly occur in tailings dams. The evolution of monitoring indexes is important for the improvement of warning accuracy in tailings dam breaks. The velocity field and outflow discharge behavior in overtopping dam-break of an iron mine tailings dam were studied. There were two stages of the tailings flow in the model test, corresponding to two types of flow state, granular flow and viscous flow, respectively. The absolute vorticity vertical line |w| vertical line was measured to reveal the influence of terrain on the velocity. An estimation equation for the maximum velocity was proposed, in which vorticity and the height difference of terrain were taken into account. The standard deviation of the velocity stack e ¯ with minus on top was used to distinguish the dam-break flow into “collision” and “non-fluctuating” regions. The velocity profiles of the transversal section were concluded to be three patterns based on the positions of the peak velocities. The three patterns well described the velocity field at different flow states. Estimation equations were proposed for the transversal section velocity profile. Based on the velocity profile equations, the estimation method of the outflow discharge was developed. This study provides a reference for improving the accuracy of tailings dam break warnings by non-intrusive monitoring methods. [ABSTRACT FROM AUTHOR]

Saturated tailings deposits in the upstream dam are at risk of static liquefaction due to elevated porewater pressure levels. The concept of a potential static liquefaction zone was conceived, and an enhanced method of slices evolving that zone was proposed. The centrifuge test modeled the aluminum tailings dam with a step-likely increasing overburden, to investigate the stress state and deformation pattern during service life. Results showed that the tailings lasted a low level of effective stress and continuous accumulation of flow deformation after the first liquefaction occurrence, implying an enduring liquefied zone under subsequent loading. For a safety design, that zone is referred to as the potential static liquefaction zone and soil inside the zone should be considered to have strength parameters from the instability line instead of the failure line. Based on this assumption, an enhanced method of slices, considering the strength reduction in the potential static liquefaction zone, was proposed. To verify the enhanced method, the centrifuge test of the liquefied tailings was simulated in GeoSlope, where a deep riskiest sliding surface, a large failure zone, and a factor of safety of less than 1 were predicted. However, the traditional Bishop method predicted a factor of safety greater than 1 for the liquefied tailings. Significant predictive differences were also observed in two other liquefied cases: the Merriespruit tailings dam and the Fundão tailings dam. [ABSTRACT FROM AUTHOR]

The awareness of tailings dam safety monitoring has widened due to the recent disasters caused by failures of such structures. The failure rate of tailings dams worldwide (i.e., the percentage of failed dams out of total) is estimated at 1.2%, compared to the 0.01% rate for traditional water dams. Most of the tailings dam monitoring guidelines suggest that the owner develops a robust surveillance program to detect possible indicators of potential failures. This paper presents a thorough review of major guidelines on tailings storage facility (TSF) monitoring and surveillance, the visual parameters to be monitored, as well as good practice in the development of monitoring systems. This paper reviews the recent literature with an emphasis on the development of monitoring systems utilizing sensors, unmanned aerial vehicles (UAVs), and satellite images that may be considered as supplementary guarantees against failure events. [ABSTRACT FROM AUTHOR]

This work aims to present and discuss a conceptual project of mining tailings dam. Therefore, specific topics on tailings dams are visited and the characterization of materials constituting such structure is reviewed in the literature. Based on parameters available in the literature, a hypothetical dam was schematized and its stability was assessed via computational analysis (limit equilibrium and finite element flow analysis). Assessing eventual design changes (additional dam heightening) and hypothetical situations (collapses in the internal drainage), it is concluded that the schematic conceptual design presents itself viable and stable given the proposed geometry and the properties of materials considered. The importance of the internal drainage system for the dam´s stability was also identified.

Due to the large scope of safety management of tailings dam and the special mountainous environment, traditional surveying and mapping means are difficult to carry out, and the deformation and displacement data of tailings dam can only be obtained through single or multi-point monitoring. Therefore, this paper proposes a tailings dam deformation monitoring and analysis method based on UAV photogrammetry, which collects the three-dimensional geographic information data of two phases of a tailings dam by UAV. The collected data of the two periods were reconstructed in three dimensions and the point cloud model was generated. The point cloud model of the two periods was compared and analyzed by using the three-dimensional spatiotemporal comparative analysis technology of geographic information. The results show that the method can realize the comprehensive monitoring of tailings dam from point to surface, and the monitoring accuracy can reach cm level, which provides a basis for the macro deformation monitoring of the tailings dam and the rapid verification and safety inspection of abnormal deformation area. Key words:tailings dam;UAV;photogrammetry;point cloud model;deformation analysis [ABSTRACT FROM AUTHOR]

In light of growing concerns over sustainability, particularly in the wake of environmental disasters like the Aznalcollar dam break, the Spanish authorities have heightened their awareness of issues surrounding ore tailings management. The main aim of this paper is to study the dynamic behavior for the dry closure of the Almagrera dam under the action of an earthquake. This study was carried out with the Plaxis 2D v9.02 program, which uses the finite element (FE) method. The dynamic analysis of the dam was interpreted in terms of deformations, displacements and principal stresses. The construction of the Uniform Seismic Hazard Acceleration Response Spectrum (USHARS) and the selection of real accelerograms for the time-history dynamic calculations is a noted feature of this research. Numerical analyses show that the dam is safe enough because a failure surface has not been formed, although several plastic zones may appear in the dam. The FE study of deformations display that the tailings may attain large deformations, displacements and failure, although this does not jeopardize the safety of the dam where the displacements are smaller than 3 mm. Neither the tailings nor the dam are expected to suffer liquefaction. It was determined that the 0.09 g threshold value is not exceeded in the acceleration-time graphs on the old reservoir field surface, which is the most critical situation. [ABSTRACT FROM AUTHOR]

The escalating scarcity of disposal areas for tailings and the prevalence of abandoned conventional tailings dams necessitate innovative construction methods, leading to the emergence of hybrid tailings dams. These dams amalgamate two conventional methodologies, enabling the revitalization and reutilization of abandoned dams by enhancing the dam height. This study aims to rigorously assess the stability and responses of hybrid tailings dams, focusing on their behaviour under static and seismic conditions, through Finite Element Method (FEM) analyses. The seismic responses of six distinct hybrid tailings dams were meticulously analysed employing the equivalent linear method. Three varying earthquake motions were considered. The analyses uncovered that the upper segment of the hybrid construction profoundly impacts the response and stability of the entire dam. Nevertheless, overlaying any other hybrid method, be it downstream or centerline, over the upstream method was found to be satisfactory under low to medium seismic conditions. One noteworthy finding was the possibility of raising existing abandoned upstream method of tailings dams with critical stability issues. It is found that it is safe to use hybrid methods of construction such as downstream and centerline over exiting upstream methods of tailings construction without compromising its stability. In conclusion, our study underscores the pragmatic and sustainable potential of hybrid methods, excluding the upstream method in upper constructions, as a viable solution to address the scarcity of disposal areas. This approach not only offers a practical means to revitalize existing tailings dams but also contributes to the advancement of hybrid tailings dam construction practices. [ABSTRACT FROM AUTHOR]

The analysis of overtopping dam break caused by extreme rainstorms and other special circumstances is very important in the feasibility analysis of new construction or expansion projects of tailings reservoirs. Reduced-scale physical model tests can directly reflect the topography and dam-break influence range, but the reasonable selection of model dam material is the key to ensure the model's similarity. Based on the similarity optimization of the limit state of scour inception of sediment particles, a new method for the model material of tailings dams can be proposed, but it needs to be verified by a similar overtopping model test. In this paper, the modeling and numerical calculation analysis of a prototype tailings dam and a similar reduced-scale model are carried out by using FLOW-3D v11.2 numerical software. The calculation results show that the model test scheme optimized by inception similarity can well reproduce the overtopping failure process of the prototype dam. [ABSTRACT FROM AUTHOR]

Tailings dam failures cause catastrophic impact on the environment and surrounding communities. Incidences of failure in the recent past have caused industrialists and researchers to seek innovative ways for proactively managing their safety and disaster mitigation. Given Industry 4.0 technologies now available, researchers are looking to develop digital tools for cost-effective, realtime monitoring of tailings dams. However, published literature indicates that a reliable framework is still lacking. This paper proposes a framework for developing a data-driven system for monitoring tailings dam stability and early warning detection. The framework relies upon digital twin simulation and machine-learning (ML) techniques, and comprises four main components: realtime data collection, digital twin modelling, ML-based early detection and prediction, and intelligence-driven decision-support. Sensors gather real-time geophysical data from monitored structure, and the digital twin uses this data to simulate dam behaviour. ML algorithms analyse the data and simulations to enable early detection of instability and failure prediction. Literature suggests that digital twin and ML-based approaches may have advantages over traditional monitoring techniques and other AI-based methods. The paper concludes with a discussion of the framework's limitations, opportunities for improvement, and potential for application in mining and geotechnical engineering. The paper serves as a basis for model development and future research. [ABSTRACT FROM AUTHOR]

The type of soil and its compactness significantly influence its permeability coefficient, which in turn affects the drainage difficulty of soil pore water and the distribution of the infiltration line. However, current tailings dam models typically consider only a single soil layer instead of taking into account the differences in soil types and compactness, resulting in a deviation between simulated results and actual conditions. To address this issue, this study proposes three models with a gradually increasing degree of layering refinement based on soil type and compactness. These models aim to simulate the variations in the infiltration line under three different strategies: constant head, rainfall, and drainage. The simulation results indicate that the average increase in the infiltration line of the three schemes after rainfall is 46.2%, 65.88%, 83.52%, respectively; the fitting percentages for each scheme of infiltration line after 720 days of drainage and the constant head stage are 72.38%, 88.27%, and 93.61%, respectively. It can be seen that the higher the refinement level of the layered model, the more sensitive it is to changes in the infiltration line. Furthermore, as the refinement level of the layered model increases, the simulation effect on the changes in the infiltration line improves, and the simulated results become more consistent with the actual situation. This finding provides a strategy and possibility for the study of the tailings dam's infiltration lines, safety, and stability. [ABSTRACT FROM AUTHOR]

In this study, a robust non-Newtonian numerical model that can simulate coupled mudflow and sediment transport processes is used to model downstream geomorphic changes during a tailings dam failure. The catastrophic breach of the Mount Polley tailings dam is studied to assess the model performance. Spatial and temporal variation of flow properties like density, viscosity, yield stress, sediment size fractions, and friction are considered in the model. A flexible triangular mesh is adopted, and this helps reduce the computational time significantly compared with structured grid with the same average resolution. High resolution multitemporal digital elevation models (DEMs) are used for the detection of geomorphic changes and estimation of erosion and deposition volumes. The results indicate that the final distribution of tailings deposits obtained from the model results is in good agreement with that obtained from topographic analysis. The model predicted the total volume of erosion and deposition with almost 93% accuracy. The tailings characteristics followed the full Bingham model during the propagation. Different runout scenarios obtained from the mudflow-morphodynamic model and a mudflow fixed-bed model are analyzed, and it was concluded that maximum mudflow depth of the flood wave is higher when bed entrainment is considered. Sediment concentration is higher in the wavefront and middle regions and lower in the tail zone. The mudflow fixed-bed model could underestimate the downstream flood arrival time. The results also confirm that the adopted approach can efficiently model the sediment budget in the study site and the volume of tailings and bed materials released to the downstream lake. Tailings dams are used to store waste solids and water generated during mining operations. Failure of such dams can cause serious damage to human settlements and the downstream environment. For public safety, it is necessary to conduct proper risk assessment, and numerical modeling is crucial for estimating flood magnitude, flood path, and flood arrival time. Tailings water is high in sediment concentration and is viscous; thus, its flow characteristics are different from that of pure water. During the collapse of tailings dam, erosion of the downstream terrain occurs, and changes in the downstream channel morphology can be potentially significant. There can also be a change in the total sediment load when additional solids get eroded from the bed layer. The modeling approach used in this study helps to model erosion and deposition patterns and estimate the downstream flood arrival time when transport of sediment in the downstream channel is considered along with the viscous nature of tailings. When conducting risk assessment of tailings dam failures and when planning for evacuation, this mobile-bed modeling approach can be implemented by design engineers and emergency planners. [ABSTRACT FROM AUTHOR]

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam's failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam's fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams. [ABSTRACT FROM AUTHOR]

Anthropogenic activities related to mining generate both progress and a vast amount of waste that is responsible for environmental degradation. The Jiu Valley is one of the areas of Romania where mining has affected large areas of land, used to build mines and tailings ponds. The former Coroiesti coal processing plant (CCPP) is such a location with a total area of 25 ha containing approximately 5.5 million tons of tailings. The assessment of the stability of tailings dams is extremely important from safety and environmental aspects. This study proposes a solution based on numerical methods for determining the stability of a section of the dam of a tailings pond. The model of tailings pond no. 1, compartment B, from the Coroieşti Coal Preparation was built using COMSOL Multiphysics. Two scenarios of stability analysis were conducted on a section of the tailings dam: the FOS was determined using the shear strength reduction (SSR) method for both the initial and the current state of this TP. This method is a modern alternative to the limit equilibrium method, and its implementation by COMSOL is new to our country, thus aligning this methodology with current worldwide trends and developments in the field. The results obtained proved to be in line with those calculated in the past with traditional analytical methods, proving that the safety criteria of the studied TP/TD are being met. [ABSTRACT FROM AUTHOR]

In China, there are more than 12,000 tailings ponds, and the number is still growing. With the rapidly increasing number of tailings ponds, the safety issue has drawn more and more attention by governments and local communities. The design and construction of each tailings pond must meet the specific requirements of a particular mining project and the changing conditions with time. This paper presents a case study of the Dahongshan Longdu tailings pond which combined upstream and centerline methods for dam construction. The Dahongshan Copper Mine and Iron Mine were facing a challenge of the disposal of increased production of tailings. The current upstream method of dam construction could no longer guarantee its safety. Therefore, the original design of tailings pond should be revised for the safety of the tailings pond. This tailings dam used centerline method for subsequent construction after total height of this dam was constructed up to 100 m by upstream method. This tailings pond initially used upstream method for the dam construction. To pile up the increased production of tailings, the dam construction method was switched to centerline method after dam height of 100 m. Numerical simulation was performed to analyze the seepage and displacement fields, stability and storage capability of the tailings dams constructed by upstream and mixed methods, respectively. Through the simulated results, the mixed method was demonstrated to be more beneficial to the practical safety management of this tailings pond than the upstream method. [ABSTRACT FROM AUTHOR]

The dry stacking of filtered tailings is an option to deal with safety-related issues involving traditional slurry disposition in impoundments. Filtered tailings can be compacted to pre-define design specifications, which minimizes structural instability problems, such as those related to liquefaction. Yet, comprehending the tailing's response under various stress states is essential to designing any dry stacking facility properly. Thus, the present research evaluated the mechanical response of cemented and uncemented compacted filtered iron ore tailings, considering different molding characteristics related to compaction degree and molding moisture content. Therefore, a series of one-dimensional compression tests and consolidated isotropically drained triaxial tests (CID), using 300 kPa and 3000 kPa effective confining pressures, were carried out for different specimens compacted at various molding characteristics. In addition, changes in gradation owing to both compression and shearing were evaluated using sedimentation with scanning electron microscope tests. The overall results have indicated that the 3% Portland cement addition enhanced the strength and stiffness of the compacted iron ore tailings, considering the lower confining pressure. Nevertheless, the same was not evidenced for the higher confining stress. Moreover, the dry-side molded specimens were initially stiffer, and significant particle breakage did not occur owing to one-dimensional compression but only due to shearing (triaxial condition). [ABSTRACT FROM AUTHOR]

The filtered tailings disposal (dry stacking) up to 300 m high is an alternative to overcome the drawbacks related to the slurry tailings storage in large impoundments as it is safer and demands smaller portions of the existing landform. Even so, the understanding of the denser and dewatered material response over a broad range of confining pressures is essential to safely design tall dry stacking tailings facilities. Accordingly, the present research assesses the mechanical behavior of compacted iron ore tailings through triaxial tests. A series of compression and extension drained and undrained triaxial tests were conducted over a wide spectrum of confinements (σ́3 ranging from 75 to 8,000 kPa) to check possible particle breakage occurrence and effects. The influence of the initial density due to compaction was, as well, evaluated since the tests were performed using specimens molded at distinct dry unit weight values. The results were analyzed in the light of the critical state soil mechanics and have indicated the existence of a curvilinear critical state line in the ν: log ṕ plane. Small particle breakage has occurred and can be associated with reduction in surface roughness, breakage of asperities, and reduction in particle angularity. Moreover, a tendency for static liquefaction was observed amongst the loosest specimens sheared under the lowest confining levels.

The dry stacking of filtered tailings is an option to deal with safety-related issues involving traditional slurry disposition in impoundments. Filtered tailings can be compacted to pre-define design specifications, which minimizes structural instability problems, such as those related to liquefaction. Yet, comprehending the tailing’s response under various stress states is essential to designing any dry stacking facility properly. Thus, the present research evaluated the mechanical response of cemented and uncemented compacted filtered iron ore tailings, considering different molding characteristics related to compaction degree and molding moisture content. Therefore, a series of one-dimensional compression tests and consolidated isotropically drained triaxial tests (CID), using 300 kPa and 3000 kPa effective confining pressures, were carried out for different specimens compacted at various molding characteristics. In addition, changes in gradation owing to both compression and shearing were evaluated using sedimentation with scanning electron microscope tests. The overall results have indicated that the 3% Portland cement addition enhanced the strength and stiffness of the compacted iron ore tailings, considering the lower confining pressure. Nevertheless, the same was not evidenced for the higher confining stress. Moreover, the dry-side molded specimens were initially stiffer, and significant particle breakage did not occur owing to one-dimensional compression but only due to shearing (triaxial condition).

There is a critical need for a global monitoring capability for Tailings Storage Facilities (TSFs), to help protect the surrounding communities and the environment. Satellite Synthetic Aperture Radar Interferometry (InSAR) shows much promise towards this ambition. However, extracting meaningful information and interpreting the deformation patterns from InSAR data can be a challenging task. One approach to address this challenge is through the use of data science techniques. In this study, the representation of InSAR metadata as Entity Embeddings within a Deep Learning framework (EE-DL) is investigated for modelling the spatio-temporal deformation response. Entity embeddings are commonly used in natural-language-processing tasks. They represent discrete objects, such as words, as continuous, low-dimensional vectors that can be manipulated mathematically. We demonstrate that EE-DL can be used to predict anomalous patterns in the InSAR time series. To evaluate the performance of the EE-DL approach in SAR interferometry, we conducted experiments over a mining test site (Cadia, Australia), which has been subject to a TSF failure. This study demonstrated that EE-DL can detect and predict the fine spatial movement patterns that eventually resulted in the failure. We also compared the results with deformation predictions from common baseline models, the Random Forest model and Gaussian Process Regression (GPR). Both EE-DL and GPR greatly outperform Random Forest. While GPR is also able to predict displacement patterns with millimetric accuracy, it detects a significantly lower number of anomalies compared to EE-DL. Overall, our study showed that EE-DL is a promising approach for building early-warning systems for critical infrastructures that use InSAR to predict ground deformations. [ABSTRACT FROM AUTHOR]

The awareness of tailings dam safety monitoring has widened due to the recent disasters caused by failures of such structures. The failure rate of tailings dams worldwide (i.e., the percentage of failed dams out of total) is estimated at 1.2%, compared to the 0.01% rate for traditional water dams. Most of the tailings dam monitoring guidelines suggest that the owner develops a robust surveillance program to detect possible indicators of potential failures. This paper presents a thorough review of major guidelines on tailings storage facility (TSF) monitoring and surveillance, the visual parameters to be monitored, as well as good practice in the development of monitoring systems. This paper reviews the recent literature with an emphasis on the development of monitoring systems utilizing sensors, unmanned aerial vehicles (UAVs), and satellite images that may be considered as supplementary guarantees against failure events.

Interferometric synthetic aperture radar (InSAR) has been effectively used to monitor surface deformation in a mining area with millimeter-level accuracy. On March 27, 2022, a tailings dam failure occurred in Shanxi Province, China, causing significant damage to surrounding houses, woodland, and roads below the tailings pond. We obtained the surface deformation map of the tailings dam before the catastrophic failure using the InSAR time-series method with a full resolution of Sentinel-1 A. This paper employed a GPU-assisted InSAR processing method for 91 Sentinel-1 images in Interferometric Wide Swath (IW) mode acquired from January 8, 2019, to March 17, 2022. The InSAR results show that during the 25 months preceding the tailings dam failure, Dam-II experienced an average cumulative LOS deformation of nearly 80 mm, while Dam-I experienced a significant deformation of more than 140 mm in the LOS direction. The analysis combining the deformation and rainfall results shows that rainfall significantly affects tailings pond deformation. In general, the deformation evolution has a high correlation with the rainfall annually, but the maximum deformation rate occurs with a delay of about one month compared to the peak rainfall. InSAR technology can significantly improve the monitoring capability of tailings dam failure and other landslide disasters, but it is limited by the observation frequency of the satellite. Thus, improving the temporal resolution of SAR data may assist in predicting tailings dam failure times more accurately. [ABSTRACT FROM AUTHOR]

Construction or enlargement of tailings ponds must consider the potential risk assessment on life safety and environmental protection in the downstream areas. Among various analysis methods, reduced scale physical model test is an important and intuitive method to carry out the impact analysis of flood overtopping tailings dam. However, the selection of model dam material for progressive overtopping dam failure is a difficult problem, and the impact of flood or debris flow can be greatly overestimated by the instantaneous dam break model tests. Based on the similarity analysis of tailing particle incipient motion, the critical inception state of the tailing particle in model dam is analyzed under the action of similar overtopping flow. Inception similarity of the model is confirmed impossible when using prototype tailings to set up model dam. Preconditions for model dam to reach the inception similarity in reduced scale physical tests are deduced, and incipient velocity tests are carried out to verify the rationality of the theoretical analysis. Taking the soil shear strength as a control method to improve the inception similarity of the reduced scale model, two feasible model dam material schemes are proposed through controlling the particle size or mixing bentonite. Although physical model tests involve multi-aspects of similarity laws, the research on the model material selection based on inception similarity optimization will provide a new reference for improving the physical model testing techniques of overtopping dam break, which can be helpful to emergency management and operational response. [ABSTRACT FROM AUTHOR]

This article presents an investigation of ground movement measurements based on a combination of TerraSAR-X and Sentinel-1 data, in opposite tracks, aiming to detect ground de-formation of the remaining dikes of Germano mine, after the Fundão dam collapse. The differential interferometry technique SBAS (Small Baseline Subset) was applied to obtain the deformation of the surface in different Line of Sight (LoS), in order to carry out the vector decomposition and generate the deformation measurements in the vertical and horizontal directions. A set of 37 single-look complex (SLC) images of TerraSAR-X (TSX), acquired during the period from 19 February 2016 to 15 May 2017, and 37 SLC images of Sentinel-1, acquired from 8 February 2016 to 15 May 2017, were used to perform this investigation. For the TerraSAR-X interferometric processing, a coherence threshold of 40%, 4 looks in range and 2 looks in azimuth, 1200 m of atmospheric filter, and 10 % of max normal baseline of the critical were used. For the Sentinel-1 interferometric processing a coherence threshold of 26%, 8 looks in range and 2 looks in azimuth, 1200 m of atmospheric filter, and 20% of the of max normal baseline of the critical were used. For both sensors a digital elevation model generated by Pleiades 1-A was used for removing the topographic phase component. The final results were consistent with the topographic in situ measurements, providing key information to make crucial decisions regarding risks, or even mitigation, repairs or emergency response, as well as for a better understanding of the on-going instability phenomena affecting the dikes and dams.

The article analyses the power of mining corporations in areas at risk of tailings dams failures in Minas Gerais, emphasising the Central Region in the context of the disasters in the Doce and Paraopeba river basins. Since these disasters, and due to changes in the federal and state regulations of tailings dams, mining companies began to exercise their territorial power incisively, defining, without prior notice, the need for the compulsory displacement of hundreds of families in communities and cities downstream of dams. Furthermore, corporate control over information and the political definition of the use of the territory substantially altered the localities' social, economic and cultural life. These dynamics aggravated the unequal power relation guided by economic dependence and the constant fear of new failures. At the same time, the mines continued operating to serve the reproduction of capital and the production/appropriation of value. The research was developed based on secondary data and analysis of media material. [ABSTRACT FROM AUTHOR]

This paper analyses the feasibility of estimating the fundamental frequency of an 85 m high cycloned-sand tailings dam located in the Central-North area of Chile using the single-station H/V Spectral Ratio Method (HVSR), calculated from seismic ambient noise and earthquakes recorded by a temporal seismic array deployed along the embankment crest, the downstream slope, and the dam toe, directly over the foundation soil. The fundamental vibration frequencies obtained from the HVSRs show consistency with results from the Standard Spectral Ratio method (SSR) calculated between the crest and the toe using the available earthquake records, particularly in the dam central part. [ABSTRACT FROM AUTHOR]

Tailings dams are special constructions that are part of a complex of works related to the installations for preparing mining masses. These constructions play a role in the mechanical treatment of wastewater and the safe storage of sterile material resulting from ore processing. The closing and greening of tailings dams is achieved taking into account the general stability of the pond and its related constructions, as well as the integration into the surrounding environment of the surfaces occupied by mining waste deposits (tailings dams). This study presents the results of the hydrogeotechnical and stability study carried out on the Gura Roşiei tailings dam location. This analysis aims to evaluate the stability degree of the three compartments that comprise the tailings deposit in order to carry out the closing and greening works of the tailings dam, and to conclude whether the idea of raising them by 1.5–2 m with tailings is feasible. This study was based on field observations, geotechnical drilling, and physical–chemical analyses of the collected samples. Due to the shallow depth, the drilling could not highlight a hydrostatic level except for the areas with excess humidity, areas represented by certain lenticular intercalations of sandy dust that yield water very slowly. These areas are not continuous and cannot define a reference hydrostatic level. All situations were analyzed by four different methods that satisfy the static equilibrium of forces or moments (Bishop and Janbu) or simultaneously of forces and moments (Spencer and Morgenstern–Price). From the point of view of the stability calculations performed in the hypothesis in which the three ponds become active for the storage of tailings, assuming a corresponding piezometric level, the resulting safety factors are relatively close to the standard values (Fs ≥ 1.4) for the static analysis, and in seismic conditions, they are at the limit of equilibrium. The NE slope of pond No. 2 shows values below the standard safety limit for this type of work. Moreover, tailings dam No. 3 presented from the calculations as being totally inadequate for the elevation. From the obtained results, it was found that the location formed by the three compartments that comprise the Gura Roşiei tailings dam presents major disadvantages for a future storage of flotation tailings, being at the same time an imminent danger to the environment. Due to its reduced capacity to release water from its pores, the settled material is still in a saturated state, and it is assumed that the foundation land, comprised of the terrace deposits of the Abrudel River, is clogged at the interface with the settled material and unable to naturally drain the excess moisture from the dam's body. [ABSTRACT FROM AUTHOR]

It is difficult to obtain reliable shear strength parameters for the stability analysis and evaluation of tailings dams in an unstable state. In this study, the sensitivity of the shear strength index to the safety factor of a tailings dam was evaluated. The cohesion C range of a tailings earth rock dam in an unstable state is determined by the safety factor, and the Morgenstern–Price method is used for inversion. During parameter inversion, uncertainty reasoning is established based on cloud theory, which overcomes the problem that the fuzziness and randomness of the quantitative cohesion value are transferred to the qualitative concept of the safety factor. The results show that the change in cohesion C has a greater influence on the safety factor Fs of the tailings dam, and the value of parameter inversion is 8.6901 kPa. The deformation and failure of tailings dams under extreme rainfall conditions are analyzed by using the modified cohesion C value. The dam toe becomes the main response area of plastic deformation and slowly expands to the interior, showing creep deformation. The displacement field gradually transfers from the accumulated tailings to the tailings dam with the flow direction, causing erosion damage. This study provides a new idea and method for parameter inversion of the shear strength index of tailings dams and provides a reference for the disaster prediction and prevention of tailings dams subjected to extreme rainfall. [ABSTRACT FROM AUTHOR]

The friction performance and compression properties of geotextile bags under different degrees of consolidation are researched through the slope sliding test, direct shear test, and unconfined compression test in this study. The geotextile bags are made up of geotextile and tailings sands obtained from a construction site of a prototype tailings dam in Yunnan Province. The slope sliding test is considered as an easy method to study the friction performance of geotextile bags with different degrees of consolidation. Through the test, the friction coefficients between the bags were obtained. Given the geotextile bags can withstand the vertical load in practical engineering, the direct shear test is also proposed and conducted. The ultimate bearing capacity of the geotextile bags with different consolidation degrees is studied in the unconfined compression test. The test reveals that the ultimate bearing capacity of geotextile bags, although featured with different moisture contents before the test, stays the same under the condition of slow loading. Finally, a stability analysis method based on the limit equilibrium theory is developed to simulate the stability of the tailings dam using geotextile bags (TDGB). According to the test results, the TDGB has demonstrated an improved stability compared with the general tailings dam. [ABSTRACT FROM AUTHOR]

This research aims to study the seepage failure characteristics of the tailing sand, as well as the seepage stability of the tailings dam in the Makeng mine, Fujian, China. Combining with post-test X-ray computed tomography, a macroscopic seepage test was employed to reveal the macro-meso seepage failure mechanism of the tailing sand. The three-dimensional (3D) model was used to analyze the seepage and safety stability of the tailings dam. Results show that the pore and particle changes of tailing sand are greatly affected by the seepage. Along the seepage direction, the migration of the 0–40 μm fine particles leads to the separation of the large pores into small pores with a diameter of 0–40 μm, which reduces the connectivity of the pores. The pore abundance values gradually converge to 0–0.6, and the pore shape becomes elongated. Furthermore, numerical studies show that the depth of the tailings dam's saturation line meets the specified requirements at both the existing and designed elevations. The tailings dam's shear displacement moves in horizontal space and develops downstream along the dam axis. Piping failure may occur on the tensile failure area of the tailings dam surface, and the shear zone near the foundation dam is likely to occur flowing soil failure at the designed elevation. [ABSTRACT FROM AUTHOR]

The analysis of overtopping dam break caused by extreme rainstorms and other special circumstances is very important in the feasibility analysis of new construction or expansion projects of tailings reservoirs. Reduced-scale physical model tests can directly reflect the topography and dam-break influence range, but the reasonable selection of model dam material is the key to ensure the model’s similarity. Based on the similarity optimization of the limit state of scour inception of sediment particles, a new method for the model material of tailings dams can be proposed, but it needs to be verified by a similar overtopping model test. In this paper, the modeling and numerical calculation analysis of a prototype tailings dam and a similar reduced-scale model are carried out by using FLOW-3D v11.2 numerical software. The calculation results show that the model test scheme optimized by inception similarity can well reproduce the overtopping failure process of the prototype dam.

The type of soil and its compactness significantly influence its permeability coefficient, which in turn affects the drainage difficulty of soil pore water and the distribution of the infiltration line. However, current tailings dam models typically consider only a single soil layer instead of taking into account the differences in soil types and compactness, resulting in a deviation between simulated results and actual conditions. To address this issue, this study proposes three models with a gradually increasing degree of layering refinement based on soil type and compactness. These models aim to simulate the variations in the infiltration line under three different strategies: constant head, rainfall, and drainage. The simulation results indicate that the average increase in the infiltration line of the three schemes after rainfall is 46.2%, 65.88%, 83.52%, respectively; the fitting percentages for each scheme of infiltration line after 720 days of drainage and the constant head stage are 72.38%, 88.27%, and 93.61%, respectively. It can be seen that the higher the refinement level of the layered model, the more sensitive it is to changes in the infiltration line. Furthermore, as the refinement level of the layered model increases, the simulation effect on the changes in the infiltration line improves, and the simulated results become more consistent with the actual situation. This finding provides a strategy and possibility for the study of the tailings dam’s infiltration lines, safety, and stability.

Anthropogenic activities related to mining generate both progress and a vast amount of waste that is responsible for environmental degradation. The Jiu Valley is one of the areas of Romania where mining has affected large areas of land, used to build mines and tailings ponds. The former Coroiesti coal processing plant (CCPP) is such a location with a total area of 25 ha containing approximately 5.5 million tons of tailings. The assessment of the stability of tailings dams is extremely important from safety and environmental aspects. This study proposes a solution based on numerical methods for determining the stability of a section of the dam of a tailings pond. The model of tailings pond no. 1, compartment B, from the Coroieşti Coal Preparation was built using COMSOL Multiphysics. Two scenarios of stability analysis were conducted on a section of the tailings dam: the FOS was determined using the shear strength reduction (SSR) method for both the initial and the current state of this TP. This method is a modern alternative to the limit equilibrium method, and its implementation by COMSOL is new to our country, thus aligning this methodology with current worldwide trends and developments in the field. The results obtained proved to be in line with those calculated in the past with traditional analytical methods, proving that the safety criteria of the studied TP/TD are being met.

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam’s failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam’s fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams.

Tailings dam is the main heavy metal pollution source in mining areas. In this study, the concentration of heavy metals in soil and water from upstream and downstream of the tailings dam was analyzed. The concentration of As, Cd, Cu, Ni, Pb, and W in tailings soil exceeded the standard value but Hg and Zn in the tailings soil were far below the standard. Average concentrations of As, Pb, and W in soil samples were above the upstream reference soil. The level of As and Pb decreases, downstream as the distance from the tailings dam increases. The mean concentrations of the heavy metals in water for Ni, Cu, Zn, Pb, and Cd were 106.3, 57.3, 21.8, 14.5, and 8.0 µg/L, respectively. The Ni contents in all studied water samples had concentrations higher than Awata River and WHO guidelines for drinking water. Both geo-accumulation and ecological risk indices have indicated significant heavy metal pollution in the study area. The overall results of this study showed that the soil and water downstream of the tailings dam were not safe and must be protected against access to humans and domestic animals. [ABSTRACT FROM AUTHOR]