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The extension of the Żelazny Most tailings store facility (TSF), which is the largest in Europe, requires the transport of large amounts of tailings, e.g., from the central area of the TSF reservoir to the new southern extension (SE). In order to use the mature fine tailings deposits located under the clarified water in the TSF reservoir, which were thickened in the process of natural sedimentation, it was decided to choose suction dredgers that collect tailings a few meters from under the water surface. The dredgers, which are most commonly used for the extraction of sand or gravel, showed the ability to pump fine flotation tailings slurry in the conducted tests. However, in order to reduce the costs of the entire operation, it was necessary to control the density of the slurry. The article presents a prototype installation for measuring the efficiency of the solid phase of the "in situ" dredging process in real time. The installation was designed for the needs of dredging a deposit of tailings that were thickened in the natural sedimentation process, and which had a particle size of below 63 μm. The installation consists of a flow meter, a densimeter, and a section for measuring the head loss of the flow of the slurry. The applied methodology allows for the current assessment of the dredger's operating parameters, which translates into a more effective–in terms of process efficiency–management of the dredger's work. [ABSTRACT FROM AUTHOR]

To better understand the seepage field in tailings dam with a drainage structure that combines drainage mat, drainage tube, and geotextile, an equivalent seepage analysis method for the drainage structure is presented. In the method, an equivalent drainage structure is suggested to replace the original drainage. It has enough size to be easily presented in the three-dimensional (3d) model of a tailings dam. According to a back analysis procedure using the quasi-3d models of a tailings dam with original and equivalent drainage structures, the material properties of the equivalent drainage structure can be obtained under the principle of drainage capacity equivalence. It is demonstrated that the suggested method is accurate enough to capture the seepage field in a tailings dam based on comparing the calculated and measured phreatic lines in a tailings dam for verification. Then, the method is employed to investigate the seepage field in a tailings dam in China for a case study. The rise of water level, damage of drainage structure, or increase of tailings discharge speed and time will lift up phreatic line. After terminating tailings discharge, phreatic line will first rise and then fall. The effect of tailings discharge on phreatic line will almost disappear after terminating tailings discharge for 24 h. [ABSTRACT FROM AUTHOR]

The overtopping failure that occurred to the reinforced tailings dam has led to devastating catastrophes, including severe environmental disasters as well as tragedy in terms of any loss of properties and life. To study the feature of overtopping erosion for the reinforced fine-grained tailings dam induced by mud-water mixture overflow, the red mud concentration of overflow, the erosion depths and erosion rate have been consistently detected and recorded by a series of physical model tests. This investigation conclusively showed that the red mud concentration for flooding over the dam slope had a nonlinear trend of first becoming larger, subsequently decreasing with the time going on in the process of tailing dam overtopping; the maximum red mud concentration achieved 19.0%. The erosion on the dam slope was shaped like a trumpet. The red mud concentration of the mud-water mixture flow affected the erosion depth significantly. The hydraulic tests simulating erosion behaviour in the reinforced fine-grained tailings were carried out with different red mud concentrations (0%, 10%, and 20%). For the mud-water mixture flow in a red mud concentration of 20%, the final erosion depth exhibited a ladder shape from the front to the trailing end (dam toe) of the tailings sample. The final erosion depths were 1.56 cm, 0.9 cm, and 0.55 cm at the front, middle, and trailing end, respectively. With the red mud concentration decreasing, the final erosion depth at the front of the tailings sample reduced significantly while increasing at the trailing end. This study brought more scientific insights into the overtopping erosion process to the reinforced fine-grained tailings dam triggered by the mud-water mixture flow at multiscale. [ABSTRACT FROM AUTHOR]

A steady global decline in the grade of chromite ores is causing an increase in the mining of low grade and complex ores. The processing of such low grade and finely disseminated ores results in the increased production of primary and secondary slimes. Slimes have very poor recovery performance in most conventional technology and are usually disposed of into tailings storage facilities (TSF). The historic slimes in the TSFs and those arising from most chrome production processes constitute potential recoverable chrome resources. In this study, the selective flocculation of slimes from a chrome processing plant in the north west province of South Africa was conducted using raw corn starch and sodium oleate as flocculants and sodium silicate a dispersant was applied on. Limited work has been reported on the flocculation of non-synthetic chrome slimes. The results showed that a slime sample with a chrome (Cr2O3) head grade of 22.92% was upgraded to a maximum concentrate grade of 42.55% at a sodium oleate dosage of 88 g/tonslurry, a sodium silicate dosage of 44 g/tonslurry, 39.61% at a starch dosage of 106 g/tonslurry and sodium silicate dosage of 62 g/tonslurry. The corresponding recoveries using sodium oleate as a flocculent were between 80-89% and 73-79% for starch. Sodium oleate showed a better performance than starch in terms of both grade and recovery. Decantation washing tests showed that the chrome (Cr2O3) grade of the concentrate can be further increased to above 44%. These results are very encouraging as they indicate that selective flocculation can achieve satisfactory upgrade ratios and recovery when processing chrome ultrafine or slime material. [ABSTRACT FROM AUTHOR]

Acceleration, displacement, stress response, and other dynamic response topics are currently the key topics of research. Because uranium tailings reservoirs are radioactive, earthquakes can also cause radon to be released. In order to monitor the acceleration response, displacement (both surface and interior), and radon exhalation rate of the dam body of the uranium tailings reservoir under various seismic peak accelerations, the shaker model test is used. When the peak acceleration is 0.7 g, the displacement swings even more visibly, and when the peak acceleration is 1.0 g, the surface of the dam shows clear fissures. However, the radon response will be quicker and stronger, and as the acceleration of the seismic peak keeps rising, the response gets stronger and stronger. As a result, the dynamic reaction can also be determined from the radon response. The findings of the tests can be used as a guide for the safe and stable operation of uranium tailings reservoirs. [ABSTRACT FROM AUTHOR]

An alternative process to obtain a high degree of dewatering tailings that produces a high-density product is presented in this article. This technology involves the combination of tailings particle grain size classification by hydrocyclones (HC) and tailings dewatering by horizontal vibratory screens (HVS). It makes it possible to dewater tailings to a high grade of performance. This alternative technology (HC-HVS) involves the recovery of water from the coarse fraction of tailings (sands) through two hydrocycloning stages, followed by a dewatering stage of cycloned tailings sands on horizontal vibratory screens, to reduce moisture content and turn it into a "cake". The resulting coarse fraction tailings are easily transported to a dry stack tailings storage facility (TSF). The fine fraction of tailings (slimes) can be dewatered on thickener equipment to recover part of the process water. Finally, this article describes the main benefits of this alternative dewatered tailings technology with an emphasis on (i) dewatering technology evolution over the last 17 years; (ii) process stages features; (iii) pilot test results; (iv) tailings properties analysis (such as particle grain size distribution, fines content) and (v) lessons learned about the experience gained in the operation of Mantos Blancos case study with dry stack tailings storage facility. [ABSTRACT FROM AUTHOR]

The mining and processing of naturally occurring radioactive materials (NORMs) could result in elevated levels of natural radionuclides in the environment. The gold mining in the goldfields of the Witwatersrand Basin of South Africa has resulted in numerous tailing dams that have high concentrations of NORM bearing residue. The aim of this study was to evaluate the radioactivity levels in tailing dams, soils and rocks, and the consequential radiological exposure to the public in the gold mining areas of Gauteng Province, South Africa. The activity concentrations of 238U, 232Th, and 40K were assessed using a gamma ray spectrometer (RS-230), and the activity concentrations ranges in the mine tailings were 209.95–2578.68 Bq/kg, 19.49–108.00 Bq/kg, and 31.30–626.00 Bq/kg, respectively. The radionuclides show significant spatial variability in soils, with high activities recorded in soils located in close proximity to tailings although regionally, the soil radioactivity levels mainly depend on the chemistry of the underlying rocks. The estimated annual effective doses were higher than the recommended regulatory limit of 0.25 mSv/y in particular tailing dams and soil impacted by tailings. Therefore, to ensure the protection of people and the environment, further monitoring and regulatory control measures targeting these areas are required. [ABSTRACT FROM AUTHOR]

The Mariana disaster, resulting from the rupture of the Fundão tailings storage facility (TSF) in 2015, was a large‐scale environmental disaster that drastically affected the entire channel of the Rio Doce, southeastern Brazil. The disaster produced substantial channel siltation, increased turbidity, riparian damage and a massive fish kill. However, the Rio Doce basin has a long history of environmental degradation, including hydroelectric dams. The latter are major threats to the ichthyofauna because they affect flow regimes, trap sediments and large wood, select generalist species, impair fish migrations and favour non‐native invasive species. In this study, we analysed the effects of the rupture as well as impacts from the construction of a run‐of‐the‐river hydroelectric dam on native and non‐native fish abundances, and species richness and composition in the middle Rio Doce.To do this, we examined fish survey data collected before and after each disturbance upriver of the reservoir, in the reservoir area and downriver of the dam. The data were separated into three temporal intervals: free‐flowing river, post‐filling reservoir and post‐TSF disaster. To assess temporal changes in native and non‐native fish species richness, we used a rarefaction method and tested it with two‐way ANOVA, which also was used to compare fish abundances. To test temporal changes in fish assemblage composition we used a PERMANOVA test.We observed no significant differences in total native or non‐native species richness as a result of the dam or the disaster. However, we did observe increased non‐native individual abundances after the TSF rupture as well as native individual abundances, depending on the location studied. The assemblage composition also changed after dam construction and the TSF rupture, except for the upriver reach after dam construction.We conclude that both the dam and the TSF rupture affected fish assemblages, favouring increased non‐native abundances, and also changed fish assemblage composition.Our results suggest that a century of landscape and riverscape pressures had extirpated the sensitive fishes from the Rio Doce before the TSF rupture. We conclude that multiple long‐term chronic disturbances can be as harmful to aquatic biota as the acute effects of a major environmental disaster. [ABSTRACT FROM AUTHOR]

The mining activity contributes significantly to the development of a country, due to the attraction for financial investments in this sector, high profits, and generation of jobs. However, the historic of serious accidents caused by the rupture of tailings dams it has shown failures in operation and risk management that begins in the project planning and extends in the choice of the method of elevation and the monitoring of the dam through the inspection and instrumentation. The accidents caused by this type of structure cause disastrous social, economic and environmental consequences. This study aims to identify the contributing causes for the occurrence of accidents with mining tailings dams and demonstrate the consequences if safety measures are not adopted to prevent disruption and guarantee functionality. The work aims to study the current challenges of mining in Brazil and optimize natural resources through the concept of circular economy, aiming to minimize the environmental impacts that can be caused to society. The precariousness and lack of hydrological studies in tailings dam projects will also be addressed in this article, as well as the need to implement public policies with environmental sustainability in waste management, aiming to reduce the risks of accidents in tailings dams, as well as to preserve mineral resources for future generations. [ABSTRACT FROM AUTHOR]

The paper presents the results of research and industrial tests of the effectiveness of the use of reagents for dust binding of dusty surfaces on the example of dry surfaces of tailings storage facilities of PJSC “InGZK” and PJSC “PivnGZK”. In the course of the research under contract No. 1205 dated 30.12.2021 between the Research Institute of Mining and Ore and PJSC "PivnGZK" from January 2022 until August 2022 two series of research on the properties of 16 reagents available on the market of Ukraine, which can be used for dust binding of dusting surfaces, were conducted, and a rating of reagents was formed according to the following indicators: stability of the protective layer; dust emission intensity; strength of the protective layer (ultrasonic method); the thickness of the protective layer; surface water absorption. According to the results of laboratory studies, the binding process of finely dispersed dust particles, which actively participate in the general process of dust cloud formation in the conditions of dust formation of dry surfaces of tailings storage facilities, was substantiated, and a general rating of reagents based on the effectiveness of their use was formed. [ABSTRACT FROM AUTHOR]

Process water used in mineral processing operations corresponds to water recovered from the thickeners and tailings dams, containing residual reagents such as hydrolyzed polyacrylamides (HPAMs). These polymers depress the flotation of different minerals, and their effect on molybdenite has been experimentally demonstrated. The objective of this work was to study the interactions between a segment of a HPAM with the face and edge of molybdenite. The sigma profile, the radial distribution functions of the HPAM, and the orientation and atomic density profiles of water molecules on the face and edge surfaces of molybdenite were calculated. The results obtained from molecular dynamics simulations showed that the interactions between the HPAM and molybdenite are mainly explained by the interactions of the amide group with the faces and edges of the mineral. Molecular dynamics simulations also showed that the HPAM molecule rearranges in such a way that the amide group moves towards the molybdenite face or edge, and the carboxylate group moves away from the mineral surface. The results obtained in the simulations showed that the interactions of the HPAM with the molybdenite edge are slightly stronger than the interaction of this molecule with the mineral face. Simulations demonstrated that the presence of the sodium and hydroxide ions reduces the concentration of HPAM around the face and edge surfaces, which is expected to affect HPAM adsorption on molybdenite. The conclusions obtained through molecular dynamics simulations are in line with the results obtained in previous studies carried out at a macroscopic scale, which reported that HPAMs adsorb onto molybdenite particles and reduce their hydrophobicity. [ABSTRACT FROM AUTHOR]

Today, seepage control in tailings dams has become an important problem due to the increased production in mining sites. Although very techniques have been developed to solve this problem, research in this field continues. The reason for this is that there is an ongoing search for a one hundred percent successful method to prevent seepage. In this study, the geochemical and geomechanical properties of paste material stored by the surface paste disposal (SPD) method were investigated by pilot field tests. To determine the effects of cement and pozzolanic materials on the geochemical and geomechanical properties of the paste, 2 different pilot-scale storage designs were observed for about 1 year, with no additives (reference) and binder added to some layers (cement and fly ash). Based on the data derived from the former laboratory investigations and with no additives and with a few layers of cement and fly ash, the two different designs were applied on a pilot scale near the existing tailings dam of a currently active mining enterprise. These designs were observed in inland conditions for about 1 year to determine the effects of seasonal changes on the material. The seepage analysis, surface crack densities, microstructural properties, consolidation, and cohesion values of these designs, which are directly exposed to atmospheric effects, were determined during the study period. According to the results obtained, the use of cement improved the volume compressibility coefficient of the material by approximately 25% compared to the reference design. However, the use of fly ash alongside cement improved the volume compressibility coefficient by about 75%. In conclusion, the use of cement made the material more resistant to external factors, and the usability of fly ash, which was used at a 50% replacement ratio with cement to bring down the cost, for long-time storage in the industry was demonstrated within the scope of the study. [ABSTRACT FROM AUTHOR]

Processed tailings in the Mixed tailings impoundment at the Macraes gold mine built up a sedimentary pile up to 100 m thick between 1990 and 2013. The tailings consist of sand-dominated fluvio-lacustrine sediments with fine (cm scale) bedding and have a mineralogical stratigraphy that reflects changing mine processes. Most of the tailings (>90%) consist of silicate minerals discarded from the flotation system throughout that time. The deepest tailings (1990–1993) have the lowest contents of sulphides as these were extracted and deposited separately. Between 1993 and 1999, tailings with up to 0.5 wt% sulphide sulphur (as pyrite and arsenopyrite) were deposited. Introduction of a pressure oxidation system in 1999 caused a substantial decrease in sulphide minerals and a parallel increase in ferric oxyhydroxide, ferric sulphate, and ferric arsenate compounds in which trace metals are dispersed. Some primary scheelite reacted during pressure oxidation conditions to form ferric tungstate compounds. Processing of auriferous sulphide concentrate from Reefton, western South Island, from 2007 introduced stibnite to the ore stream, and this was readily oxidised to form insoluble As-bearing ferric antimonate. [ABSTRACT FROM AUTHOR]

The Neotropical otter (Lontra longicaudis) is a semi-aquatic predator that occurs in a wide geographic distribution in the Neotropical region, and can be used as indicator of ecosystem health. In January 2019, the Paraopeba River, which has historically been affected by anthropic activities, was impacted by the B1 iron ore tailings' dam collapse. This might have caused severe negative impacts to the entire fauna of the region. We carried out an inventory along the Paraopeba River to assess the current occurrence of the Neotropical otter in such asystem. The results obtained indicate the occurrence of this species in the study region eight months after the damage, with records upstream and downstream of B1 dam. [ABSTRACT FROM AUTHOR]

The article reports that the Engineers and Geoscientists BC took actions to improve dam safety in BC, which included producing professional practice guidelines for site characterization for dam foundations in BC updated existing guidelines to confirm the duties of the "Engineer of Record" and holds professional development seminars.

As a nonuniform structure, tailings dam undergoes complex and chaotic nonlinear changes, under the joint influence of multiple dynamic or nondynamic factors. These changes make it difficult to predict the deformation of tailings dam accurately with a numerical model. To solve the problem, this paper proposes a grey deformation prediction model optimized by double coefficient (GDPM-DC). Unlike a single grey prediction model, the GDPM-DC does not mutate significantly but adapts well to specific scenarios. Besides, the model can smoothen and stabilize the original data and thus achieve accurate prediction of the deformation of tailings dam. The main results are as follows. The GDPM-DC made more accurate predictions than the traditional grey model (1, 1) (GM (1, 1)), the grey model based on logarithmic transformation (GM-LT), and the grey model optimized by weight coefficient (GM-WC). It significantly improved the overall prediction accuracy of the vertical and transverse deformations of the dam and controlled the relative error of the predicted seepage pressure to 2.79%–3.71%. Moreover, the model could forecast the trend component and random fluctuation component of seepage pressure effectively, fit the increasing trend in stages 1–3 and the decreasing trend in stages 3–9, and realize the quantitative prediction of deformation law for the operating tailings dam. The research results provide a meaningful reference for the instability analysis and safety management of tailings dam. [ABSTRACT FROM AUTHOR]

Plants growing in metal‐polluted sites can be a source of micro‐organisms suitable for bio‐assisted phytoremediation strategies. In this work, three endophytic fungi from the roots of Poa stuckertii and Poa pratensis, two grasses that naturally colonize a Lead‐Zinc tailing storage facility in Southern Chile, were isolated and identified. The leachate of the tailing sands showed a Pb content of 1·36 ± 0·71 ppm, and a pH of 7·3. By amplifying the ITS1/ITS4 region of fungal ribosomal DNA, the isolates were identified as Bjerkandera sp., Microdochium sp. and Sarocladium sp. When the growth media was supplemented with 50 ppm of Pb at pH 4·5, Microdochium sp. showed an 80% decrease in the biomass, but the biomass production of Bjerkandera sp. and Sarocladium sp. was not affected by the same treatment. The accumulation of Pb in Microdochium sp. increased as a function of the concentration of the metal in the growth media, between 48·3 and 241·3 μmol l−1. We showed that two Poaceae plants growing on a Lead‐Zinc tailing storage facility are a source of endophyte fungi and that Pb had a differential effect on the growth of the isolated fungi independent of the plant of origin. [ABSTRACT FROM AUTHOR]

On 4 August 2014, a breach developed in a portion of the embankment at the Mount Polley Tailings Storage Facility following foundation failure. This paper explores the mechanism of this progressive failure in view of pronounced three-dimensional stability effects identified in this slope. The findings of a three-dimensional deformation analysis of this failure are reported. The results demonstrate that its initiation can be explained in terms of minor strain-weakening within a thin shear band in the glaciolacustrine unit at the base of this slide, combined with the delayed mobilization of shear resistance in the shell zone owing to its relative ductility, along with the reduction in the levels of mobilized shear resistance in the upstream region of the slide resulting from a loss of confinement and (or) failure in extension caused by the translational displacements the base of the side. While recognizing the limitations of analyses alone, simulation suggests that strain localization in a shear band with a thickness not exceeding 12–13 cm is requisite for the initiation of this failure. [ABSTRACT FROM AUTHOR]

In the last 20 years many mining projects around the world have applied a tailings deposition technology named "dry stacking of filtered tailings" at tailings storage facilities (TSFs). This technique produces an unsaturated cake that allows storing this material without the need to manage large slurry tailings ponds. The application of this technology has accomplished: (i) an increase in tailings water recovery, (ii) a reduction of the TSF footprint (impacted areas), and (iii) a decrease in the risk of physical instability, being TSFs self-supporting structures under compaction (such as dry stacks), and (iv) a better regulator and community perception satisfying the need of stable TSFs. This paper presents the main features, benefits, and advances in filtered tailings technology applied in Chile and Peru with emphasis on: (i) filtering technology evolution over the last decade: description of main equipment, advantages, and disadvantages, (ii) design considerations for main TSF geometrical configurations, tailings transport and placement systems, TSF water management, TSF operational and emergency plans, and TSF progressive closure, (iii) operation experiences at site-specific conditions, (iv) technology acceptance in regulatory frameworks, (v) lessons learned and advances, and (vi) new trends and future developments, considering technical, environmental, regulatory frameworks and cost-effective manners. [ABSTRACT FROM AUTHOR]

Historic tailings dams and their associated mine waste can pose a significant risk to human and environmental health. The Wheal Maid mine site, Cornwall, UK, serves as an example of the temporal evolution of a tailings storage facility after mining has ceased and the acid-generating waste subjected to surficial processes. This paper discusses its designation as a contaminated land site and reviews our current understanding of the geochemistry, mineralogy, and microbiology of the Wheal Maid tailings, from both peer-reviewed journal articles and unpublished literature. We also present new data on waste characterisation and detailed mineral chemistry and data from laboratory oxidation experiments. Particularly of interest at Wheal Maid is the presence of pyrite-bearing "Grey Tailings", which, under typical environmental conditions at the Earth's surface, would be expected to have undergone oxidation and subsequently formed acidic and metalliferous mine drainage (AMD). The results identified a number of mechanisms that could explain the lack of pyrite oxidation in the Grey Tailings, including a lack of nutrients inhibiting microbial Fe(II) oxidation, passivation of pyrite mineral surfaces with tailings processing chemicals, and an abundance of euhedral pyrite grains. Such research areas need further scrutiny in order to inform the design of future tailings facilities and associated AMD management protocols. [ABSTRACT FROM AUTHOR]

To characterise the relationships among the hazards associated with tailings storage facility (TSF) dam failure, interpretive structural modelling (ISM) is used to hierarchise, structuralise and visualise them. Based on evidence, 15 hazards in four categories are identified, and are classified into seven levels and four clusters. The results show that seven hazards can be regarded as the fundamental hazards. The majority of hazards associated with technology factor can be seen as transactional hazards and are closely related to the water balance problem. The proposed ISM method offers theoretical reference and improves risk management for the TSF and the mining industry. [ABSTRACT FROM AUTHOR]

Polymers are effective products widely used in the solid-liquid separation of industrial wastes. Making solid-liquid separation in the wastes ensures that the wastes can be stored more regularly and efficiently, while removing the high water content from the landfill makes the accumulated wastes not a threat to the environment and reduces the waste volume by a significant amount, thus reducing the storage costs. Polymer performance is measured by turbidity tests. Many factors affect the effectiveness of the polymers used in solid-liquid separation, such as mixing speed, mixing time, settling time of slurry, temperature, and storage time which is the time elapsed between the use of the solid polymer after it has been prepared as a liquid solution. In this experimental study, the waste obtained from the tailings dam of the Kütahya Espey boron enrichment (concentrator) plant in its natural form, representing an industrial waste, was first dried, and then a waste ground suspension was prepared by taking the water/soil ratio in the tailings dam into account. The factors affecting the polymer performance in solid-liquid separation were determined by mixing four anionic polymers with different molecular weights into the prepared soil suspension. According to the findings, the ideal mixing speed has been determined to be 200-250 rpm, the mixing time as 1-3 minutes, and the settling time of the suspension between 2-4 minutes. Also, the suspension temperature was found to be a factor that could affect the turbidity and flocculation according to the polymer type. Moreover, the polymer solution can be used for 7 days without a decrease in its effectiveness, 24 hours after it is prepared. [ABSTRACT FROM AUTHOR]

In this study, a new approach is proposed for the stability analysis of tailings storage facility (TSF) dams. Given the considerable scale of such objects, te correct identification of geotechnical layers for computational models and the determination of reliable parameters can present significant challenges. Therefore, the investigation focuses on distinguishing additional sublayers within a geological substratum to enhance the credibility of stability assessment. The procedure of sublayer separation is directly based on soil parameters derived from geotechnical tests and it aims at reducing the variability in the parameters of individual sublayers. Specifically, the segmentation technique known as the Gaussian mixture model (GMM) is employed for this purpose. Subsequently, the spatial arrangement of sublayers within the finite element model domain is identified using the kriging technique. Utilizing Monte Carlo simulations statistical distribution of factor of safety (FOS) is obtained for the structure. Finally, the stability is assessed using the Cornell reliability index. The application of this developed methodology is demonstrated through a case study of the Żelazny Most TSF. Additional sublayers are identified in Neogene clays constituting the dominant layer beneath the facility. In total, six different segmentation variants are proposed and their performance is evaluated. The results show that the segmentation of additional sublayers produces a clear reduction in the scatter of the FOS. Consequently, the estimated simplified reliability index surpasses that of the case, which does not involve the separation of additional layers. [Display omitted] • Segmentation of sublayers improves credibility of the TSF stability assessment. • Performance of segmentation is demonstrated in the case study of real TSF. • Segmentation of sublayers provides computational model with more accurate information on subsoil. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are critical for the energy transition; however, their 'green' credentials are at odds to the environmental damage as part of mining, recovery and processing. Opportunities may exist to recover REEs from uranium tailings as part of the 'economic rehabilitation' of tailings storage facilities. [Display omitted] • Water leach able to extract rare earth elements (REEs) from tailings. • More than 10,000 t of REEs could be recovered using an in situ water leach. • REEs recovery using water leach potential exceeds the uranium recovery during initial mining. • Water leaching and recovery of REEs from tailings allows for economic rehabilitation. • In situ extraction from tailings allows for low water, low energy recovery. The global energy transition from fossil fuels to renewable sources poses substantial challenges to increase metal production, including industry-critical rare earth elements (REEs). Environmental and social concerns obfuscate the production of these 'green' metals and only ∼1% of REE demand is met from recycling. This work highlights the potential for the 'economic rehabilitation' of the Mary Kathleen Mine, a relinquished uranium (U) mine with very high (∼3 wt%) total REE concentrations within the tailings storage facility (TSF). Leaching of the tailings revealed that approximately 5% of the REEs are water-soluble, suggesting the possibility for in situ extraction. Using an in situ water leach, the projected total REE recovery is >10,000 t, which would exceed the total amount of U recovered (7,532 t) during the initial mining operation. The proposed in situ recovery would offer a truck-free mine, using solar energy and water recycling technologies to recover REEs from a waste source, reducing environmental contamination. [ABSTRACT FROM AUTHOR]

The long-term management of tailings from former uranium (U) mines requires an in-depth understanding of the hydrogeological processes and water flow paths. In France, most of the legacy U mines are located in fractured crystalline (plutonic) rocks, where the intrinsic subsurface heterogeneity adds to the uncertainties about the former extraction and milling activities and the state of the mine when production was ceased. U ores were mainly processed by sulfuric acid leaching, leading to high-sulfate-content mill tailings now contained in several tailing storage facilities (TSFs). The La Ribière site, located in western central France, is a former open-pit and underground U mine, closed in 1992 and used to store mill tailings. This site is being used as a test case to establish a workflow in order to explain and predict water flow and subsurface contaminant transport. A conceptual model of water flow and sulfate transport, at the scale of the La Ribière watershed, is first developed based on available information and hydrogeochemical monitoring. Recent geophysical investigations allows refining this model. Electrical Resistivity Tomography (ERT) proves to be efficient at localizing the extent of the highly conductive sulfate plume inherited from the U-mill tailings, but also at imaging the weathering profile. Magnetic Resonance Sounding (MRS), despite the limited signal intensity due to the low porosity in crystalline rocks, gives some insight into the porosity values, the depth of the fractured layer and the location of the low-porosity ore-processing muds. Based on this conceptual model, a 3D flow and non-reactive transport model with the METIS code is developed and calibrated. This model allows predicting the evolution of the sulfate plume, but will also be used in future investigations, to build reactive transport models with simplified hydrogeology for U and other reactive contaminants. • Parsimonious approach to modeling a small but complex site with large uncertainties. • Water table and long-term sulfate monitoring highly valuable for model calibration. • Sulfate plume extent localized thanks to ERT sounding. • Boundaries of underground workings in former open pit identified by MRS sounding. [ABSTRACT FROM AUTHOR]

Understanding the origins of sediment transport in river systems is crucial for effective watershed management, especially after catastrophic events. This information is essential for the development of integrated strategies that guarantee water security in river basins. The present study aimed to investigate the rupture of the B1 tailings dam of the Córrego do Feijão mine, which drastically affected the Brumadinho region (Minas Gerais, Brazil). To address this issue, a confluence-based sediment fingerprinting approach was developed through the SedSAT model. Uncertainty was assessed through Monte Carlo simulations and Mean Absolute Error (MAE). Estimates of the overall average contributions of each tributary were quantified for each station and annually during the period 2019–2021. It was observed that the sampling point PT-09, closest to the dam breach, contributed to almost 80% of the Paraopeba River in 2019. Despite the dredging efforts, this percentage increased to 90% in 2020 due to the need to restore the highly degraded area. Additionally, the main tributaries contributing to sediment increase in the river are Manso River "TT-03" (almost 36%), associated with an area with a high percentage of urban land use, and Cedro stream "TT-07" (almost 71%), whose geology promotes erosion, leading to higher sediment concentration. Uncertainties arise from the limited number of available tracers, variations caused by dredging activities, and reduced data in 2020 due to the pandemic. Parameters such as land use, riparian vegetation degradation, downstream basin geology, and increased precipitation are key factors for successfully assessing tributary contributions to the Paraopeba River. The obtained results are promising for a preliminary analysis, allowing the quantification of key areas due to higher erosion and studying how this disaster affected the watershed. This information is crucial for improving decision-making, environmental governance, and the development of mitigating measures to ensure water security. This study is pioneering in evaluating this methodology in watersheds affected by environmental disasters, where restoration efforts are ongoing. [Display omitted] • The confluence-based sedimentary footprint developed after the dam breach. • The dilution factor of the tributaries is key to the dilution of sediments. • The River stands out due to its anthropogenic input. • The Cedar Stream has contributions due to its geology. • The drains carried out confirm the effectiveness of pollution control. [ABSTRACT FROM AUTHOR]

• Evaluation of Crago process to beneficiate iron ores. • Tailings recovery strategies in iron ore industry. • Direct anionic flotation of hematite applied to iron ores. • Comparison between reverse cationic flotation and anionic direct flotation for iron ores. Mont-Wright mine is an important asset of ArcelorMittal located in the province of Quebec, Canada. This asset annually produces 25 million tons of iron ore concentrate with an assay of 66 % Fe, achieved through a beneficiation circuit comprised entirely of spiral concentrators. Nevertheless, 45 million tons of tailings are discarded to the tailings dam and, due to the intrinsic inefficiency of the spiral concentrators used there, the iron content increases in the size fraction below 106 µm, which presents a good potential to be recovered. Thus, the Crago flotation process was evaluated to recover the iron contained in the finest fraction of the Mont-Wright tailings. Since it was patented in 1942, the Crago process with fatty-acid rougher flotation followed by deoiling and amine cleaner flotation has become the standard for phosphate flotation in USA operations. When applied to Mont-Wright tailings, the Crago process was able to produce a concentrate assaying 65.63 % Fe and 2.14 % SiO 2 , from a sample with 20.96 % Fe. When compared to a usual reverse flotation circuit, Crago based flowsheet was more selective and presented better results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Drone surveys accurately estimate the volumes of Zn-Pb tailings ponds. • Chemical and mineralogical characterization are crucial for tailings valorization. • 3D block models were used to estimate the variability of Zn-Pb and their resources. • The characteristics of TBM tailings encourage their reprocessing. The Touissit-Boubker mine (TBM) in Morocco processed Zn and Pb-containing sulfides, resulting in substantial tailings stored in open facilities from 1962 to 2002. These tailings present both environmental challenges and economic prospects. Our study focuses on characterizing two primary TBM tailings impoundments, T12 and T17, and exploring their reprocessing potential. Samples were collected using reverse circulation drilling (RCD) method and analyzed for their physical, chemical, mineralogical, and environmental characteristics. Results informed a 3D block model estimating Zn, Pb, and Ag residual resources. Physical characterization shows that T12 exhibits a D 80 particle size of ∼ 122.3 µm, while T17 measures ∼ 162.8 µm. High Zn (∼2 %), Pb (∼1.5 %), and Ag (∼14 ppm) content is noted. Carbonates host mineralization, while major sulfides (pyrite, sphalerite, galena) show intense alteration. T12 displays higher sulfide liberation than T17, with modest liberation in larger fractions (>200 µm) and increasing significance in smaller fractions (<50 µm). Acid-base accounting confirms non-acidic residues due to abundant neutralizing minerals. The 3D block model estimates a total tonnage of 23.2 Mt, with 370 Kt of Zn, 140 Kt of Pb, and 160 thousand Kg of Ag. This study offers new insights into previously unexplored TBM tailings through drilling, suggesting the potential for significant economic and environmental benefits through reprocessing. [ABSTRACT FROM AUTHOR]

Catastrophic breaches of water and mine waste retaining impoundments in recent history have emphasized the severity and consequences to the downstream environment. In this study, the applicability and suitability of the XBeach numerical model for modelling earth dam failures driven by overtopping with water is explored by detailed comparison with controlled experimental data. The XBeach model is applied to simulate laboratory-scale breaches caused by overtopping failure of dams constructed with uniform sand at the Queen's University Landslide Flume by Walsh et al. (2021a). The model sensitivity to boundary conditions for different virtual flume sizes, different sediment transport equations that influence erosion rates, and the process of avalanching are investigated. The model results are in best agreement with laboratory measurements when the Soulsby-van Rijn sediment transport formulation is used, which depends on grain size, and the avalanching module is activated, indicating the importance of these processes. The model is also run for different dam geometries to investigate the influence of upstream slope angle, which is relevant for tailings dam breach analyses. The results indicate that for flatter slopes the model is in closer agreement with observations of the peak discharge, while for steeper slopes the model results are better for breach duration time. Overall, XBeach provides promising results for the prediction of the dam breach outflow hydrograph at the laboratory scale and has potential to improve understanding of earth dam failure outcomes with further investigation. • XBeach is applied to simulate the failure and morphological evolution of earth dams. • Results are compared to laboratory measurements for a range of upstream slopes. • XBeach is a promising tool for predicting the breach outflow hydrograph response. [ABSTRACT FROM AUTHOR]

Their soil behavior index HT ht ([7]) is superior to 2.95, indicating a claylike behavior. On average, HT ht . This paper presents a discussion of "Stability Analysis of Upstream Tailings Dam Using Numerical Limit Analyses" by Andrew J. Whittle, Hayel M. El-Naggar, Sherif A. Y. Akl, and Abdullah M. Galaa. https://doi.org/10.1061/(ASCE)GT.1943-5606.0002792. [Extracted from the article]

Clay mineral content has an important influence on the mechanical behaviour of tailings, and this mechanical behaviour significantly affects the stability of tailings dams. X-ray fluorescence (XRF) and X-ray diffraction (XRD) tests were carried out on tailings from three different regions. The chemical and mineral composition of the tailings are analyzed. The strength and failure deformation of the tailings were studied by laboratory triaxial compression tests. The effect of clay content on the behaviour of tailings was investigated. The microfabric of tailings sample was examined with the scanning electron microscope (SEM) and nitrogen adsorption tests. The results show that the confining pressure corresponding to the samples exhibiting strain hardening increases with the increase of the content of clay minerals. The cohesion of tailings increases linearly, and the specific surface area decreases as the content of clay minerals increases. Nitrogen adsorption test results reveal from a microscopic point of view that changes in pore structure are associated with the content of clay minerals. The higher the content of clay minerals is, the higher the proportion of micropores is (aggregated interior). Macroscopically, the overall porosity decreases and the size of the pores increases with clay content, which will directly affect the mechanical properties of tailings. [ABSTRACT FROM AUTHOR]

This study aims to characterize the seismic responses of silt-interlayered stratified sandy tailings slopes. In order to achieve this, a series of model tests were carried out in an advanced centrifuge shaking table. The experimental results demonstrate that sandy tailings slopes interlayered with silts are more prone to flow failure compared with homogeneous slopes. The failure process of a steep silt-interlayered sandy slope is further elaborated in detail, and two modes of tailings release have been identified. The initial loading cycles may only lead to localized deformation near the relatively shallow silty layer; however, there is continuous build-up of excess pore water pressure in deeper sandy tailings. With increasing the number of loading cycles, more sandy tailings start to spread laterally, and ejection of tailings may occur. After ejection, the excess pore pressure turns to dissipate, while the tailings near slope crest become liquefied and then flow toward the downstream direction layer by layer, leading to tailings release. This is the first mode of tailings release. Due to the continuous lateral spreading, the displaced tailings eventually arrive at the crest of the starter dam and then flow along its slope at the downstream side, leading to tailings release. This is the second mode of tailings release. Those unique and invaluable observations can be used to improve the seismic design of tailings impoundments and to validate associated numerical methods. [ABSTRACT FROM AUTHOR]

Currently, catastrophic failures have occurred in tailings deposits that have demonstrated the importance of continuous monitoring of the constructive and operational status of these structures to improve their understanding and reduce risk. In many cases, dam failures are preceded by a series of anomalies such as: excessive deformation on the surface, the appearance of stress cracks or acceleration trends. If these are captured in time, they can be of great support for early warning systems or for activating risk mitigation procedures, which can ultimately lead to avoiding failures. Synthetic aperture radar differential interferometry (DInSAR) techniques measure surface deformation by processing the radar phase difference of at least two complex SAR images acquired at different times over the same area. These techniques are very useful for measuring deformations in tailings deposits since they provide high-precision periodic information over large areas, and can even be used in adverse weather conditions, unlike optical satellites. This article shows the results of the application of interferometric analysis of surface deformations in tailings dams, which allow the detection of outstanding deformations, acceleration trends and estimates of the moment of failure in its structures. The processing tools are applied by studying some important international failure cases of tailings deposits that have occurred in recent years. Advanced DInSAR techniques of persistent scatterers (PS InSAR) are used for the study. The results obtained are compared with complementary geotechnical studies carried out on these case studies. [ABSTRACT FROM AUTHOR]

Proper tailings storage facilities (TSF) management can be done by monitoring various variables, such as moisture, which influences at physical and chemical stability phenomena. Nowadays, there are no continuous moisture controls due to the dangers associated with taking samples in tailings, generally in low-density states, making access difficult. Due to the recent hyperspectral imaging technologies and the successful use in monitoring interest variables (moisture, fines content, mineralogy) in areas such as hydrology and agriculture, therefore, this research uses hyperspectral images to estimate surface moisture in TSF using copper and iron tailings samples, which are subjected to active illumination from a 980 nm laser and monitored in a desiccation process in the moisture range from saturation to dry state, including density and fine content effects. Results show a parabolic relationship between moisture and light reflection, which, added to the use of the normalized difference vegetation index (NDVI), allow estimating the surface samples moisture content, generating an auspicious method for the continuous monitoring of humidity in TSF. [ABSTRACT FROM AUTHOR]

The progressive advance of sophisticated numerical models to represent the behaviour of dams has displaced simplified static analyses and has given more credibility to dynamic analyses. However, the current Chilean regulation DS248 of SERNAGEOMIN that defines the necessary analyses to guarantee the stability of these structures still requires both analyses. When the source of the design earthquake is interplate, the expressions to determine the static seismic coefficients have given consistent results when determining the safety factors and comparing with dynamic analysis, unlike what has been seen for the intraplate case where the safety factors have been more conservative. In this work, a new different expression is proposed for Chilean intraplate earthquakes derived on a concept of iso destructive potential, which allows better coherence between both analyses. [ABSTRACT FROM AUTHOR]

The catastrophic failure of the Córrego do Feijão Dam 1 in January 2019 has raised many questions regarding the safety of tailings storage facilities constructed by upstream methods. The stability of these structures is strongly affected by the internal stratigraphy and properties of the hydraulically deposited, segregated tailings materials (from slimes to coarse sands) and by control of seepage conditions. The authors conducted an independent review of site investigation data reported by an Expert Panel (December 2019) and evaluated the stability for a critical section of the Feijão Dam 1 using 2D numerical limit analyses under various representations of fill stratigraphy and shear strength properties. The results show that the structure has a low factor of safety, FS=1.11–1.16 on average, based on conventional assumptions of drainage conditions for fill strata. The computed failure mechanism is strongly affected by the presence of a layer of normally consolidated, low permeability slimes near the base of the fill, and by the lack of drainage provisions within the starter dam. The analyses show a clearly defined critical mechanism of failure over the full height of the fill and suggest that the dam has smaller margins of safety than previously published limit equilibrium results. The analyses do not resolve or identify causes of the actual dam failure, which occurred more than three years after the end of construction but do suggest that more reliable methods of slope stability are needed in design. [ABSTRACT FROM AUTHOR]

In mining operations, the failure of a tailings storage facility (TSF) can result in a dangerous debris flow with high potential energy, leading to catastrophic damage including major loss of life, enormous economic losses, and serious environmental pollution. In this paper, to examine the causes, consequences, and measures against the TSF failure, a bow-tie failure analysis model is employed. As a combination of a fault tree and an event tree, the bow-tie model is an effective tool for studying TSF failure. For the design, construction, and operation stages of the life cycle of a TSF, there are three major analytical procedures adopted in this paper: identifying the causes and consequences of a failure; establishing the fault tree and event tree; and proposing targeted mitigation measures. The main conclusions are as follows. A total of 44 types of causes are identified in this study: 5 types at the design stage, 13 types at the construction stage, and 26 types at the operation stage. A total of 78 safety measures based on four levels are introduced, consisting of 9 measures at the design stage, 20 measures at the construction stage, and 49 measures at the operation stage. From the perspective of emergency response, four kinds of protective safety measures for the consequences of failure are put forward. Finally, the bow-tie model is applied to the 980 Gou TSF failure in China to validate the effectiveness and feasibility of the model. [ABSTRACT FROM AUTHOR]

The presence of anglesite (PbSO4) in complex sulfide ores negatively affects the separation of Cu-Pb sulfides and sphalerite (ZnS) due to lead activation, and PbSO4 rejected to tailings dams contaminates the surrounding environment with lead. To address these problems, this study investigated the application of ethylene diamine tetra acetic acid (EDTA) pretreatment extracting PbSO4 to ZnS flotation and the recovery of the extracted Pb2+ as zero-valent Pb by cementation using zero-valent iron (ZVI). The application of EDTA pretreatment could extract ~99.8% of PbSO4, thus depressing ZnS floatability from 82% to 30%. In addition, cementation using ZVI could recover ~99.7% of Pb2+ from the leachate of EDTA pretreatment. [ABSTRACT FROM AUTHOR]

This article gives an overview of solid waste and tailing generated by the mining activity over the years in Albania. It presents the geographical distribution of the disposal areas giving a quantitative and qualitative assessment of this waste. It reveals that the best approach to deal with mining waste is their recycling to recover lost mineral products deposited in the mining waste and tailing dam. This loss is due to the type of technology used over the years in mines and to the low efficiency of the processing equipment; nonetheless, the new treatment methods can represent a great potential for the recycling industries in the mining activity. At the same time the rehabilitation of the disposal areas is of great importance. [ABSTRACT FROM AUTHOR]

Capillarity influences the long-term stability of the dam greatly and affects the sustainable development of tailings dam. The online monitoring capillary water rise test system was independently developed by SM3001B temperature and humidity sensor, SU9101B RS485 converter, SV3010 data acquisition system, and other equipment to carry out the whole process test of water absorption and water release of tailings with different particle sizes. The results show that the capillary rising trend of tailings with different particle sizes is basically consistent, the relationship between the rising height and the diameter are negatively correlated, and the logarithm function can better fit the height of capillary rising over time well enough. The water content of tailing capillary zone decreases with the height, and the smaller the size of tailings, the greater the change of water content. The water release process of tailings is an unsaturated permeability process, which largely depends on the saturation before water release. The larger the particle size of tailings is, the smaller the water content after water release. Based on the above results, the relationship between capillary diameter and tailings particle size was discussed, and the relationship formula between water content change and particle size was deduced. The research results systematically show the water migration law under the tailing capillaries. It is suggested that the unsaturated tailings water content index should be added in the monitoring of the saturated surface of tailings dam. [ABSTRACT FROM AUTHOR]

In the Quadrilátero Ferrífero Region, located in the state of Minas Gerais – Brazil, the utilization of recycled water from the tailing dams in the reverse cationic flotation of siliceous iron ores is common practice. In such process, ore concentrates assigning dolomite (2.5% to 10%) besides quartz in the mineral gangue, do not reach the desired specification for the production of blast furnace pellets (≤2% SiO2) given the loss of selectivity occurring in the separation of quartz from the Fe-bearing minerals, which can be related to a rise in the ions Ca and Mg in an aqueous medium resulting from the dissolution of dolomite. With a view to improving the reverse cationic flotation route for this type of ore, fundamental studies (microflotation trials, zeta potential, adsorption/Fourier-transform infrared spectroscopy) into the effect of the Ca and Mg ions in the cationic flotation with the use of pure quartz and hematite mineral samples were carried out. The results attained with the Ca ions were presented in previous studies by the authors. The current investigation presents the results achieved with the Mg ions, added in water as MgCl2. In the microflotation trials carried out at pH 10.5, amine dosage for maximum recovery of quartz (2.5 ppm) and hematite (50 ppm) was applied. A strong depression of hematite by starch was confirmed, which did not occur with quartz. In the case of the Mg ions, a stronger depression effect was observed, if compared to starch, for the two minerals, starting from a dosage of 10 ppm of MgCl2. After the conditioning of both minerals with 10 ppm of MgCl2, followed by conditioning with 10 ppm of starch, the recoveries attained were negligible (3.5% to 4.4%). Based on thermodynamic data, zeta potential measurements, and infrared spectroscopy, it was concluded that the strong depression effect caused by the Mg ions on both minerals owes to the adsorption of the Mg2+ and MgOH+ species and also the precipitation of Mg(OH)2, where the starch is chemically adsorbed, preventing further amine adsorption. Only quartz recovery was reestablished after the complexation of the Mg ions in the water by ethylenediaminetetraacetic acid having close molar concentrations to the molar concentration of the Mg ions followed by starch conditioning. The results presented indicate the need for a reduction in the concentration of Mg in the water used, before flotation is conducted. [ABSTRACT FROM AUTHOR]

Static liquefaction of mine tailings has been the interest of many studies as these materials are generally deposited in a loose condition and stored at high saturation ratios. Yet few researchers have investigated the behavior of mine tailings in stress paths involving extensional consolidation or shearing in extension. In this study, the results of a set of experiments aimed at investigating the static liquefaction behavior of saturated loose gold mine tailings samples in triaxial compression and extension shear tests are described. Monotonic tests are carried out on isotropically and K0 -consolidated samples to assess the effect of stress-induced anisotropy and mode of shearing on the instability and critical state behaviors of tailings. The comparison of undrained extension and compression shearing behaviors of samples consolidated to similar densities and stress conditions show a profound difference in their undrained shearing responses. This is attributed to the angular shapes of tailings particles that amplify the effects of particle orientation and sample fabric, as well as microstructural changes induced by different loading paths. Postliquefaction and yielding undrained shear strengths and effective friction angles from different modes of consolidation and shearing are examined. In both undrained compression and extension tests, tailings samples exhibit a limited liquefaction behavior after yielding, followed by a strain-hardening (dilative) behavior. Differences in tailings behavior under different loading directions and anisotropic stresses indicate the importance of considering the effects of these phenomena on the stability analysis of mine tailings dams. [ABSTRACT FROM AUTHOR]

Brazil has a large number of degraded areas due to iron mining and other elements. In 2015, an iron mining tailings dam belonging to "Samarco Mineração SA", located in the municipality of Mariana, state of Minas Gerais, collapsed, causing the greatest environmental disaster in the country's history, due to the spill of 62 million m3 of red mud. The red mud was deposited on slopes, foothills of mountains, intermountain depressions and floodplains, contaminating soils and waters with amines, amides and sodium from the flotation of iron mining residues and causing the formation of surface crusts on the land and hard-setting formation. Different researches were carried out to evaluate and recover degraded soils—Leptosols, Cambisols, Ferralsols, Gleysols and Fluvisols, however the problems are still present and phytoremediation techniques were practically not applied. Phytoremediation is the use of plants to extract, filter, degrade, stabilize, or otherwise reduce mobility, bioavailability, or concentrations of pollutants and stands out as an example of a low cost, minimally invasive approach for the remediation of large-scale contaminated areas. In view of the degraded areas due to the collapse of the "Samarco Mineração SA" tailings dam, this article suggests phytoremediation strategies to rehabilitate the soils in different geomorphological units and the challenges to be faced in the future, pointing out research and the need for the involvement of professionals from different areas of knowledge. [ABSTRACT FROM AUTHOR]

Static liquefaction has been associated with numerous recent failures of tailings storage facilities (TSFs) around the world (e.g., the 2019 Brumadinho failure). These failures lead to devastating consequences for the environment and civil infrastructure as well as the loss of human lives. In this study, we present trends for the mechanical response of mine tailings considering (i) triaxial tests, (ii) bender element tests, and (iii) consolidation tests on 53 mine tailings materials (including recent case histories). These materials have a broad range of states, particle size distributions, and compressibility. The trends are evaluated in the context of static liquefaction using critical state soil mechanics concepts, focusing on the variation of the shear strength (residual and peak), state and brittleness soil indexes, excess pore pressure indexes, instability stress ratios, and dilatancy. In particular, we highlight that mine tailings' mechanical properties reflect both the properties of the particles themselves and the relative proportions of different particle sizes. For instance, the observed trends suggest that particle gradation influences the small strain stiffness and dilatancy; the proportion of voids to the size of fine particles influences strength, and particle shape affects dilatancy. Finally, we propose static liquefaction screening indexes based on the observed trends. [ABSTRACT FROM AUTHOR]

The sedimentary structure is important for the engineering design, operation, and safety evaluation of tailing dams. For upstream-method tailing dams, tailing slurry flows and deposits in the pond and forms a complex dam structure. Ore drawing parameters (e.g., slurry concentration and flow rate) have significant influence on the sedimentary structure of tailing dams. However, there is a lack of unified and quantitative understanding of the complicated effects of ore drawing parameters on the deposition behaviour of tailings. In the present study, flume tests were applied to investigate the characteristics of the sedimentary structure of tailing dams. Seven ore drawing experiments were conducted to simulate different slurry concentrations and flow rates. The distribution of characteristic particle sizes d 50 and d 10 of sediment was obtained. Furthermore, considering two dominant features of particle size distribution, a mathematical model for the equation between characteristic particle size and deposition distance was established. The exponential part of this equation describes the decreasing trend of the characteristic particle size, and a smooth step function is introduced to characterize the abrupt decrease in particle size. The experimental data of d 50 and d 10 in all these test cases can be approximated by the equation with correlation coefficients R 2 greater than 0.861. As the slurry concentration of ore drawing increases, the hydraulic sorting gradually weakens. The characteristic particle size distribution curves corresponding to a larger flow rate are generally located above those corresponding to a small flow rate, indicating that the larger the flow rate is, the coarser the sediment. This study provided useful information for the determination of ore drawing parameters in actual tailing dams. The mathematical model of tailings' particle size distribution can be further used for refined modelling of tailing dams, so as to analyse the safety and stability of the dams. [ABSTRACT FROM AUTHOR]

As a result of developing technology and scientific studies, employing dam tailings as critical raw material and vital economic reserve has become widespread recently. Employing dam tailings as a main ingredient of CPB (cemented paste backfill) can offer benefits to mining operations. This study deals with the use of dam tailings in CPB, considering the mechanical and geotechnical aspects. CPB was prepared at fixed solid and cement contents (72%, and 5%, respectively) and tested for different cure ages varying from 3 to 56 days. The results disclosed that the strength of filling increased over time, with the exception of 56-day cured CPB having high sulfur minerals where strength decreased sharply. The reasons behind these strength surges could be clarified by CPB's basicity, which quickens the hydration of cement. Voids between tailings grains are also occupied by hydration products, resulting in the high strengths. Due to the fact that higher sulfate contents can cause lower pH values within CPB, this is one of the factors that should be considered for the backfill's strength performance. The cement tends to increase the backfill's pH in short term, but pH of long-term cured backfills decreases because of dam tailings which is inclined to acid formations and erosions. This is a sign that the deformation properties of CPB are deteriorated. Depending on curing time, CPB's water content and void ratio decrease, but their surface areas increase. The resulting data will endow to better apprehend the effects of dam tailings on CPB quality integrating cost and quality. [ABSTRACT FROM AUTHOR]