Tailings Storage Facility Research Articles

Restoration of Biological Potential in the Territory of the Gold-Processing Plant Tailings Storage Facility

The features of the impact on the natural environment of the gold-processing plant tailing dump are considered. The factors that slow down the natural recovery of disturbed areas have been revealed. Attention is drawn to the fact that it is necessary to carry out a biological stage of land recultivaiton with respect to the natural-geographical and socio-economic conditions of the area where the gold-processing plant is located in order to restore the productivity of disturbed lands. An algorithm of plants selection for biological recultivaiton is presented. The factors that can affect the successful reforestation of the area are specified.

Numerical Investigation on the Impact of Tailings Slurry on Catch Dams Built at the Downstream of a Breached Tailings Pond

Tailings storage facilities (TSFs) are known as a time-bomb. The numerous failures of TSFs and the heavy catastrophic consequences associated with each failure of TSFs indicate that preventing measures are necessary for existing TSFs. One of the preventing measures is to construct catch dams along the downstream near TSFs. The design of catch dams requires a good understanding of the dynamic interaction between the tailings slurry flow and the catch dams. There are, however, very few studies on this aspect. In this study, a numerical code, named LS-DYNA, that is based on a combination of smoothed particle hydrodynamics and a finite element method, was used. The numerical modeling shows that the tailings slurry flow can generally be divided into four stages. In terms of stability analysis, a catch dam should be built either very close to or very far from the TSF. When the catch dam with an upstream slope of a very small inclination angle is too close to the tailings pond, it can be necessary to build a very high catch dam or a secondary catch dam. As the impacting force can increase and decrease with the fluctuations back-and-forth of the tailings slurry flow, the ideal inclination angle of the upstream slope of the catch dam is between 30° and 37.5°, while the construction of a catch dam with a vertical upstream slope should be avoided. However, a catch dam with steeper upstream slopes seems to be more efficient in intercepting tailings flow and allowing the people downstream to have more time for evacuation. All these aspects need to be considered to optimize the design of catch dams.

Ecological footprint accounting of mining areas and metal production of the world

Mining is environmentally disruptive which requires tons of earth materials to be removed and causes modification in original land cover. The processing of materials also requires huge amount of energy. In this study, we calculated the Ecological Footprint (EF) of built-up and carbon absorption land for global mining activities with a dataset provided by Werner and colleagues. We first corrected the yield factor and equivalence factor of built-up land. The life cycle inventory to calculate the EF of carbon absorption land was obtained from literatures. According to the findings, tailings storage facility, waste rock dump and riverine tailings disposal had higher EF of built-up land. EF of carbon absorption land was significantly huge, and underground mines had generally higher values than surface mines whereas surface mines had higher EF of built-up land. We also discussed some mechanisms regarding how to reduce the EF of carbon absorption land.

On reliability of inferring liquefied shear strengths from simple shear testing

A laboratory study was carried out to compare the behaviour of loose tailings under simple shear loading using a torsional shear hollow cylinder device (TSHC) and a direct simple shear (DSS) device, with a focus on shear strength at high strains. This work was carried out on tailings for which the critical state line (CSL) had already been defined, to enable the results to be examined in a critical state framework. The testing indicated that the shear strengths measured at high strains by the DSS apparatus were significantly higher than those measured by the TSHC under undrained simple shear loading conditions. The likely more uniform and ideal simple shear conditions developing within the TSHC, along with the better agreement of results obtained using this equipment with the expected behaviour based on the test initial states and tailings’ CSL suggest that for loose specimens the DSS may overestimate shear strength at high strains. This observation was confirmed by comparing the results of this study with other published data where both CSL and DSS test results were available. The important implications of this observation for the design and analysis of tailings storage facilities (TSFs) in the context of laboratory measurement of liquefied strengths are outlined.

Effects of thermal modification on the separation of clay-containing waste slurries

This paper summarizes the results of studies on the use of thermal modification in the separation of slurries of clay-containing ores. It is currently vital to minimize the environmental footprint of tailings storage facilities of mining and processing enterprises and municipal waste landfills handling liquid wastes and to ensure their respective sanitary and epidemiological safety. The main liquid waste management problems are due to high process water consumption, high energy costs for dewatering and drying of concentrates, caking and congelation of concentrates, complexity and environmental hazards of storing wet waste (tailings), unsuitable for use as mine backfill material, as well as the use of inefficient TSF liner systems with potential soil and effluent contamination risks. This article considers the properties of clay-containing slurries, coal tailings, and halitic potash flotation tailings. It is shown that heat treatment improves waste slurry separation. For dry kaolin separation tailings, heat treatment at 200–400 °C significantly reduces tailings plasticity and fluidity, weakening soil interparticle cohesion and facilitating larger internal friction angles of the particles. The resulting data is used to analyze the potential applications of clay-containing ore processing wastes as a replacement for cement and lime in soil stabilization, land improvement, and mine reclamation, or as components in liner systems of municipal solid waste landfills.This study was carried out under the grant issued by the Russian Science Foundation (project No. 19-79-10114).

A new look at the statistics of tailings dam failures

Tailings dams are commonly built incrementally to increase the storage capacity of the Tailings Storage Facility (TSF), usually without interrupting the mining activities. Dam management practices, lack of knowledge on tailings behaviour and the poor performance of monitoring and management processes have resulted in disastrous tailings dam failures with human and economic losses, as well as huge environmental consequences to ecosystems and local communities. In the literature, correlation analyses have been carried out considering different variables: stored volume, released volume, runout distance, dam height, peak discharge. Several databases of tailings dam failure are available online, each with different levels of detail. This paper computes the statistics of tailings dam failures using an up-to-date database on failures and a catalogue of existing TSF. The existing correlations between stored and released volumes have been verified using a larger database. The new proposed regression analysis considers the functional relationship between released volume and characteristics of the dam such as height and stored volume (i.e., dam factor). The effect of construction type, fill material and failure mode on the released volume has also been evaluated as well as the frequency of tailings dam failure as function of the construction method. Tailing dams built using the upstream construction method turn out to be more prone to failure, and more susceptible to static and dynamic liquefaction. The new correlation provides more reliable estimates of the expected released volume as a function of dam height and stored volume and should prove useful for runout analyses and risk assessment of tailings dam failure. Finally, the analyses carried out show that there is no correlation between the water pond extension and the released volume.

Geo-Accumulation Index of Manganese in Soils Due to Flooding in Boac and Mogpog Rivers, Marinduque, Philippines with Mining Disaster Exposure

This paper presents the effects of flooding on the accumulation of manganese (Mn) in soils within proximity of the Boac and Mogpog rivers in Marinduque of The Philippines. Marinduque, an island province in the Philippines, experienced two catastrophic tailings storage facility (TSF) failures in the 1990s that released sulfide-rich tailings into the two major rivers. The Philippines experiences 21–23 typhoons every year, 11 of which pass thru Marinduque that causing inundation of floodplain areas in the province. A flood hazard map developed using LiDAR DEM was utilized for the Boac and Mogpog rivers for an accurate representation of flooding events. A portable X-ray fluorescence spectrometer (pXRF) and a Hannah multi-parameter device were used for the on-site analyses of Mn concentration and water physico-chemical properties, respectively. Spatial grid mapping with zonal statistics was employed for a comprehensive analysis of all the data collected and processed. Correlation analysis was carried out on Mn concentrations in soil and surface water, electrical conductivity (EC), total dissolved solids (TDS), pH, temperature, curve number (CN), and flood heights. The curve number indicates the runoff response characteristic of the Mogpog-Boac River basin. The results show that 40% of the total floodplain area of Boac and Mogpog were subjected to high hazards with flood heights above 1.5 m. The Mn content of soils had a statistically significant moderate positive correlation with flood height (r = 0.458) and a moderate negative correlation with pH (r = −0.438). This condition suggested that more extensive flooding promotes Mn contamination of floodplain soils in the two rivers, the source of which includes the mobilization of Mn-bearing silt, sediments, and mine drainage from the abandoned mine pits and TSFs. There is also a strong negative correlation between pH and Mn concentrations in surface water, a relationship attributed to the solubilization of Mn-bearing precipitates based on geochemical modeling results. Using Muller’s geo-accumulation index, 77.5% of the total floodplain of the two rivers was identified as “moderately contaminated” with an average Mn soil content of 3.4% by weight (34,000 mg/kg). The Mn contamination map of floodplain soils in the Mogpog and Boac rivers described in this study could guide relevant regional, national, and local government agencies in planning appropriate intervention, mitigation, remediation, and rehabilitation strategies to limit human exposure to highly contaminated areas.

Manganese Pollution in Mining-Influenced Rivers and Lakes: Current State and Forecast under Climate Change in the Russian Arctic

Mining regions in different parts of the world have been associated with the significant pollution of water, sediments, and soils by manganese and other chemical elements. This study assessed the degree of geochemical transformation caused by open-pit extraction and processing of mineral resources in the Kovdorsky District of Murmansk Oblast, 20 km from the Russia–Finland border. A second objective was to predict further changes co-driven by industrial pressure and high climatic instability in the polar region. The field study involved sampling water and sediments from virgin background streams and from the tailings storage facility, settling ponds, rivers, and lakes affected by ore mining and disintegration. Laboratory analyses included the study of elemental composition, redox potential, alkalinity and acidity, organic matter content, and other geochemical characteristics for a better understanding of pollutant migration patterns. We revealed elevated levels of potentially toxic elements in surface waters and bottom sediments which pose a risk to the human health via the household and drinking water supply. Pollution with manganese (Mn) was found to be the major environmental issue. Its natural presence in the river water was overridden a hundredfold by anthropogenic enrichment. This is problematic as Mn is easily bioaccumulated, which can lead to unwanted ecotoxicological effects, and—in the case of prolonged exposure to high doses of Mn and its compounds—to detrimental human health impacts. We believe that the changing climate may raise the water flow and thus expand the area of the hydrochemical anomaly. On the other hand, the activation of self-purification and dilution processes could lead to decreasing environmental Mn concentrations.

Effect of Freeze–Thaw Cycles on Mechanical and Microstructural Properties of Tailings Reinforced with Cement-Based Material

In China, more than 10,000 Tailings storage facilities (TSF) have been created on the ground surface through mineral mining processes, these TSF occupy a large amount of land. The strength of the tailings is too low to be able to stand on its own without strengthening. In order to save land resources and alleviate the damage to the environment caused by mineral mining, it is necessary to reinforce the TSF so that they can store more tailings. China is one of the countries with the largest area of permafrost and seasonal frozen regions, accounting for about 75% of the country’s total land area. The problem can be exacerbated in these regions where the freeze–thaw effect can further degrade the strength of tailings. A review of the literature suggests that there is little research on the mechanical and microstructural properties of tailings reinforced with cement-based materials under freeze–thaw conditions, especially when the tailings are to be discharged to land for sustainable development. This study investigates the effect of freeze–thaw cycles on the mechanical properties and microstructural changes of tailings reinforced with cement-based materials to mitigate environmental hazards. Unconfined compressive strength (UCS) tests, scanning electron microscopic images, X-Ray Diffraction tests, thermogravimetry tests and mercury intrusion porosimetry tests were conducted on samples of tailings. The results from this study show that freeze–thaw cycles reduce the UCS of all the tested samples eventually, but the frozen temperature does not significantly affect the UCS. The larger number of freeze–thaw cycles, the more damage is to the surface morphology and the matrix of the tailings. The results presented in the paper can help engineers and managers to effectively transport the TSF to other locations to minimize environmental hazards to achieve sustainable production of mineral mining processes.

Hazards identification and characterisation of the tailings storage facility dam failure and engineering applications

ABSTRACT 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.

Long-term evolution of heap surface of paste tailings under erosion / Evolução a longo prazo de pilha da pasta de rejeitos sujeita a erosão

Many mines are moving from conventional tailings storage facilities to filtered tailings disposal systems. The benefits of these systems include increased water recovery, reduced size of containment landfills, improved facility safety, and reduced environmental impact. In geotechnical terms, the challenges are to find the correct way of waste disposal: whether in piles of dry sandy tailings or co-disposal waste rock. The long-term evolution of the surface of fine and sandy tailings stockpiles is a matter of concern. The goal of this study was to quantitatively evaluate the temporal evolution of a paste tailings pile, using a computational model of landscape evolution. For this, SIBERIA, a simulator of the evolution of landscapes under the action of runoff and erosion, was used. The effect of erosion on a trunk-pyramidal tailings pile with about 21% of slope after long periods of decommissioning (100 and 250 years) was studied. The SIBERIA modelling data considered the surface roughness and the average diameter of the sediment particles and the typical properties of iron ore tailings. The results indicate that for a lower Manning roughness coefficient and larger average apparent diameter of the sediment particles (or clods), the lower the sediment transport will be and, therefore, in the long term, the greater will be the integrity of the tailings pile.

Assessing the undrained strength cross-anisotropy of three tailings types

The cross-anisotropic nature of soil strength has been studied and documented for decades, including the increased propensity for cross-anisotropy in layered materials. However, current engineering practice for tailings storage facilities (TSFs) does not appear to generally include cross-anisotropy considerations in the development of shear strengths. This is despite the very commonly seen layering profile in subaerially deposited tailings. To provide additional data to highlight the strength cross-anisotropy of tailings, high-quality block samples from three TSFs were obtained and trimmed to enable hollow cylinder torsional shear tests to be sheared at principal stress angles of 0 and 45° during undrained shearing. The consolidation procedures were carried out such that the drained rotation of principal stress angle that would precede potential undrained shear events for below-slope tailings was reasonably simulated. The results indicated the significant effects of cross-anisotropy on the undrained strength, instability stress ratio, contractive tendency and brittleness of each of the three tailings types. The magnitude of cross-anisotropy effects seen was generally consistent with previous published data on sands.

Rainfall-induced groundwater ridging and the Lisse effect on tailings storage facilities: A literature review

The failure of tailings storage facilities (TSFs) results in the discharge of significant quantities of hazardous waste material into the natural environment. Research studies relating to slope instability have identified physical mechanisms such as rainfall-induced erosion, liquefaction, and shear failure as the main triggers. The generation of transient pressure waves and the mobilization of pre-event water in the unsaturated zone have been found to trigger shallow landslides in natural hillslopes. In this paper we review these physical mechanisms, known as groundwater ridging (GWR) and the Lisse effect (LE), from other studies. Previous researchers have explained both these phenomena through field and laboratory observations, numerical modelling, as well as conceptual discussions. These case studies demonstrate the impact of rainfall characteristics on the generation of transient pressure waves that rapidly increase the phreatic surface and change pore water suction. Reference is also made to the influence and behaviour of physical porous medium characteristics on the establishment of a continuous water phase that facilitates the transmission of an induced pressure head. However, previous studies fail to recognize the possibility that the pressure increase in pre-event water through pore air propagation could cause slope instability in tailings dams. The authors suggest that the physical properties and hydraulic behaviour of unsaturated porous tailings media make it susceptible to GWR and the LE, resulting in the creation of a potential failure plane.

Towards a sampling protocol for the resource assessment of critical raw materials in tailings storage facilities

Resource estimates are crucial to assess the economic potential of tailings storage facilities (TSF) for re-mining and the extraction of critical raw materials. However, a lack of consensus exists on best practices in sampling for this purpose. This study aims to address this gap by assessing different sampling schemes for the resource classification of TSFs. To do so, one layer of a TSF was sampled with regular and nested grids of varying sizes and additional random holes. Systematic spatial trends in the data were fitted with low-order polynomial functions of the coordinates and the grayscale values of a historical aerial photograph of the same layer of the TSF. Variography was performed on the trend residuals, and exponential or Gaussian variogram models were fitted. Universal Sequential Gaussian Simulation was then used to produce 1000 realisations of the potential ground truth. The optimum sampling strategy was investigated by re-sampling these realisations with varying sample densities and configurations and using geostatistical modelling of the re-sampled data to assess uncertainties on the estimated metal tonnages. Robust estimates of metal tonnages can be achieved at relatively low sampling densities, particularly with regular grids. When historical image information is used, spatial variability is better reproduced, and a lower number of samples is required to reach a certain confidence level. Furthermore, an approach to approximate expected errors on grades/tonnages estimated with a given sampling scheme was developed to assess whether further sampling is required. Overall, the findings of this study have clear and transferrable implications for the best-practice sampling and modelling of TSFs and their critical raw material resources.

Mechanism of failure of the Mount Polley Tailings Storage Facility

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.

Importance of seismic wave frequency in FEM-based dynamic stress and displacement calculations of the earth slope

Abstract Reliable assessment of earthen dams’ stability and tailing storage facilities widely used in the mining industry is challenging, particularly under seismic load conditions. In this paper, we propose to take into account the effect of the dominant frequency of seismic load on the stability assessment of tailing/earthen dams. The calculations are performed by finite element modelling (FEM) with the Mohr–Coulomb failure criteria. To separate the frequency content from other dynamic parameters describing the seismic wave, synthetic waveforms with identical amplitude and attenuation characteristics, but differing spectral characteristics have been used. The analysis has been performed for three different slope angles and two scenarios of seismic wave propagation. Consequently, the changes of total displacement and shear stresses depending on the frequencies have been determined and clearly show that lower frequencies cause higher stress levels and displacement. Finally, the response surface methodology has been applied to determine how different parameters affect the slope stability under dynamic load conditions. Overall, this study is a first step to improve the existing methods to assess slope stability when considering seismic load.

The Potential Health Costs of PM10 Impacts on a Gold Mine Village, during Company Liquidation: An Analysis of 2013–2017

Windblown dust from tailings storage facilities (TSFs), particularly in towns with liquidated mining companies, exacerbate air pollution. Companies of suddenly closed mine operations evade the responsibility of environmental and socio-economic care required by law. It is common for suddenly closed mines to have poorly rehabilitated TSFs which become a significant source of pollution by dust for the surrounding communities. There is strong evidence that acute exposure to high levels of air pollutants causes significant mortality and morbidity. However, very few studies have estimated the externalities of PM10 emanating from gold TSFs especially when a mine closes suddenly owing to company liquidation. By exploring the externalities of PM10 arising from wind erosion of suspended particulate matter from TSFs, this study fills an existing gap in the literature. A ‘bottom-up’ approach was implemented in this study following the External Energy (ExternE) project, and a gold mine operation that was liquidated between 2013 and 2017, was used as the case study. In this study, the externality of PM10 estimated was the cost of illness focusing specifically on respiratory-related illnesses. The results showed that the estimated cost of illness associated with PM10 inhalation was a total of R 5,560,022 including assessments of both neighboring Wedela and the Gold mine village based on the threshold concentration set by the South African National Ambient Air Quality Standards (NAAQS) guideline and R 66,092,760 when considering the Fund for Research into Industrial Development Growth Equity (FRIDGE), Airshed and Infotox. Thus, it was concluded that air pollution by windblown dust from partially rehabilitated TSFs has the potential to significantly affect surrounding mining communities’ socio-economic status through poor health and the costs thereof.

On some uncertainties related to static liquefaction triggering assessments

Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering (SLT) have been made. These include applications of critical-state-based models in a stress–deformation framework to identify if in situ conditions are approaching a level where SLT could occur. However, several important uncertainties remain. In this work, three of these uncertainties (geostatic stress ratio K0, intermediate principal stress ratio and principal stress angle from vertical) were investigated, along with their effects (both independently and in conjunction) on the identification of SLT and slope failure. These uncertainties were examined through a series of numerical analyses of an idealised TSF. Various values of K0 were used to examine their effect on SLT, while different approaches were taken to assess the potential effects of the intermediate principal stress ratio and the principal stress angle from vertical on instability. This work revealed that the current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo SLT. Experimental and in situ test programmes that may be useful in reducing this uncertainty are outlined.

Повышение уровня извлечения золота при комбинированной переработке золотосодержащих свинцово-цинковых руд

The ore of the Novo-Shirokinskoye deposit is processed at the processing plant of JSC Novo-Shirokinskoye Mine according to the gravity-flotation scheme. The technological scheme for processing gold-containing lead-zinc ores consists of two nodes: 1 – gravity; 2 – flotation. The gravity node for the extraction of free gold (the extraction proportion of free gold into the gravity concentrate is not more than 30%) is realized with the help of jigging machines, screw separators and concentration tables. The flotation node includes: collective cycle, including the main, control and two partial operations; lead cycle, including the main, control and one recleaner operation; zinc cycle, which includes the main, control and three cleaning operations. The ore of the Novo-Shirokinskoye deposit belongs to the primary type, since the degree of its oxidation is 3 %. Final (marketable) products obtained at the factory during ore processing of the Novo-Shirokinskoye deposit are: combined lead concentrate of the LC-8 brand, corresponding to TU 1725-002-24722376-2011 "Lead concentrates"; zinc concentrate of the ZC-3 brand, corresponding to TU 1725-001-24722376-2011 "Zinc concentrate". Zinc flotation tailings are dump and stored in a tailings storage facility. Due to the tendency to reduce the lead content in the ore, the dependence of the reduction in the extraction of gold into the flotation concentrate is manifested. Considering the use of the traditional reagent of potassium butyl xanthogenate - C5H9OS2K (further BPX) as a collector, does not give the desired results, a search for combinations with new reagents is required. The object of research is gold–containing lead-zinc ores. The subject of the study is the modes of the flotation process of enrichment of gold–containing lead-zinc ores using the collector BPX and the new reagent Aeroflot BTF 15221 of the company "Kvadrat Plus". The main idea of the work is to increase the efficiency of flotation enrichment of gold–containing lead-zinc ores by determining the optimal combination of the known reagent of the collector BCC and the proposed Aeroflot BTF15221

THE STUDY OF PROPERTIES OF SODA PRODUCTION WASTES AS ANTI-ICING REAGENTS

The article considers the possibility of reducing the man-made load on surface and ground waters in Lysychansk-Severodonetsk industrial agglomeration caused by numerous sludge collectors and tailings storage facilities of various industries formed many decades ago. The paper provides information on the location and technical condition of the sludge collectors of the liquidated "LYSSODA" manufacture (Luhansk oblast), the amount of waste currently stored in them as well as the impact of these wastes on the quality of groundwater in the area where the sludge collectors are located. The work shows one of several possible options for using such wastes as a valuable secondary mineral raw material for obtaining a marketable product. The averaged data on the chemical composition of the solid phase of sludge and indicators of the liquid phase composition are given. According to the results of the analysis of scientific and technical information, it has been found that such wastes can ultimately be used for the production of anti-icing reagents. The obtained results of research on the dependence of the freezing point of working solutions on the concentration of salts, including the added corrosion inhibitors (triethanolamine, hexamethylenetetramine), indicate the feasibility of using soda ash production waste to obtain effective liquid anti-icing reagents without a mechanical component, while the optimal amount of added corrosion inhibitors is 0.5% wt. Such reagents can be used both undiluted at temperatures up to minus 20oC and strengthened to 15-20% wt. by calcium chloride at temperatures up to minus 40°C with consumption on highways at the level of about 100 g/m2 of the treated surface.