This study presents an extensive numerical investigation of the stability of a geosynthetic-reinforced tailings dam embankment slope subjected to surface loads from retained pyrite tailings slurry upstream of the dam. The analysis was performed on an embankment with an inclination of 1V:2.5H on the upstream slope and 1V:2H on the downstream slope. The dam embankment rests directly on previously deposited pyrite tailings that have dried over time and are sufficiently consolidated to support the embankment. The variable parameters considered in this study include the geosynthetic reinforcement length across the failure zone, effective cohesion (c′), effective angle of internal friction (ϕ′), total unit weight of the embankment clay (γ), and the number of reinforcement layers (N). The results revealed that the safety factor of the embankment slope increased with the increasing length of the geosynthetic reinforcement across the failure zone, shear strength parameters c’ and φʹ, and unit weight, γ . Increasing the total unit weight of embankment clay from 13 kN/m3 to 21 kN/m3 resulted in a 61
In the Hongdunzi coal mining area, prolonged coal extraction has elevated F− and NO3− levels in groundwater, raising ecological and health concerns. This study integrated hydrochemical analyses and machine-learning methods to identify the most important variables in groundwater and evaluate the non-carcinogenic risks of contaminants through a risk assessment model. The random forest model outperformed the support vector regression model in predicting F− and NO3− concentrations, exhibiting superior generalization and capability in capturing complex hydrogeochemical processes. F− enrichment was closely associated with NO2−, well depth, K+, Na+, and SO42−, reflecting the combined influence of the redox environment, vertical hydrogeological conditions, and the effect of mining activities on prolonged water–rock interactions. In contrast, the NO3− concentration was primarily related to Cl−, NH4+, NO2−, and water level, underscoring the synergistic effect between agricultural inputs, mining-related nitrogen sources, and enhanced vertical hydraulic connectivity between aquifers. Health risk analysis showed that drinking water ingestion accounted for over 95
The migration mechanism of dissolved organic matter (DOM) in water, soil, and sediment from the coal mining subsidence area of the Huabei Xutuan Mine was investigated using three-dimensional fluorescence-parallel factor analyses (EEMs-PARAFAC), self-organizing map (SOM), and Fourier infrared spectroscopy (FT-IR). The results revealed that DOM in all environmental media was predominantly derived from endogenous sources and exhibited a low degree of humification. Distinct compositional differences were observed among the three matrices: humus-like components were more enriched in the water, whereas protein-like substances dominated in soil. In the sediment, PARAFAC analysis indicated that the overall DOM composition was predominantly humus-like, while the SOM revealed protein-like fluorescence signals associated with microbial metabolites. Structural analysis further demonstrated that the DOM in the water contained more aromatic and oxygen-containing functional groups associated with microbial processing, while the soil and sediment DOM exhibited relatively stable structures influenced by mineral-organic interactions. The subsidence-induced hydrological conditions, characterized by waterlogging and weak hydrodynamics, facilitated the transformation of soil organic matter into the sediment and promoted the redistribution of DOM across environmental compartments. Microbial activity and soil–sediment interactions were identified as key drivers regulating DOM composition and migration pathways. These findings highlight the critical role of DOM source and structure in controlling its environmental behavior and provide new insights into organic matter dynamics and pollutant transport in artificial aquatic ecosystems formed by mining subsidence.
During deep coal mining, the mine floor can be highly susceptible to water inrush under the combined effects of high in-situ stress and elevated pore pressure. To elucidate the mechanical response and failure mechanisms, a series of triaxial compression tests were conducted under a confining pressure of 38 MPa. The pore pressure was set to 0, 6, 12, and 22 MPa, and specimens of a siltstone mine floor were tested under both natural and saturated conditions. With increasing pore pressure, both the peak strength and elastic modulus of the siltstone decreased continuously. Meanwhile, the Poisson’s ratio increased, indicating less stiffness and enhanced radial dilation. The failure mode gradually changed from high-angle shear failure to a combined shear–tensile failure. This transition was accompanied by an increased number of fractures and the development of multidirectional, interconnected cracks. The elastic strain energy density decreased markedly as pore pressure rose, suggesting a reduced energy storage capacity before failure and a more concentrated energy release during failure. Under high pore pressure and saturated conditions, the plastic strain ratio decreased while the softening rate increased. These results reflect a behavioral transition from ductile slipping to brittle fracturing. This study reveals a coupled evolution mechanism of “stiffness weakening–fracture coalescence–abrupt energy release” in siltstone under high pore pressure. It also clarifies the physical causes of floor water inrushes and provides a theoretical basis for water inrush prevention and disaster prediction in deep coal mines.
Pit lakes are increasingly proposed in mine closure plans across Canada's Athabasca Oil Sand sites. An accurate understanding of water movement, above and below ground, is crucial for effective closure landform design and tailings management. This study integrates the hydraulic mixing cell (HMC) method into the HydroGeoSphere (HGS) model to precisely track water movement within modeled catchments and estimate source water contributions from distinct watershed parts to better understand surface and groundwater movement. The Lake Miwasin Watershed is a pilot-scale pit lake catchment in the Canadian Boreal shield, constructed and operated by Suncor Energy Inc. A HGS model of the Lake Miwasin catchment was constructed by Aquanty Inc. for Suncor Energy Inc. The HGS model calibration and validation targeted surface water flow, lake level, deep and shallow groundwater levels, and actual evapotranspiration (AET). Using the HMC method, the water contribution for distinct hydrologic response units (HRUs) was estimated. The results illustrated the HGS model's proficiency in simulating water balance components within the Lake Miwasin Watershed. HMC analysis revealed the flat HRU as the primary contributor to the Lake Miwasin inlet flow, with contributions varying based on climatic conditions. Inter-annual investigations showed that lower saturation levels in late summer facilitated greater infiltration, resulting in increased contributions from the swale HRU to lake inflow. The study underscores the effectiveness of the HMC method within the HGS hydrologic model for understanding water movement across constructed pit lake watersheds. This method and resulting knowledge could inform strategic reclamation planning.
Mining activities generate large volumes of waste, including tailings rich in natural radionuclides and potentially toxic elements. These wastes accumulate on-site and are washed into mining ponds, contaminating water used by miners and nearby communities, posing serious health risks. Water samples from gold and kaolin mining sites in the Ife-Ilesha schist belt were analyzed for radionuclides (40K, 238U, 232Th), metals, and semi-metals using gamma and atomic absorption spectroscopy. Using a Monte Carlo simulation (MCS) method, a probabilistic health risk assessment was performed to estimate the ingestion dose and excess lifetime cancer risk (ELCR) for exposed miners. MCS-based risk assessment revealed elevated cancer and non-cancer risks. Ingestion doses from naturally occurring radioactive materials range from a best-case scenario (0.56 mSv/y) to a worst-case scenario (0.92 mSv/y), which both exceed the World Health Organization recommended limit of 0.1 mSv/y for drinking water. To prevent long-term health effects, miners and local communities should avoid consuming these waters.
Acidic sulfate-rich drainage waters generated during the storage of cyanidation tailings near Ursk (Kemerovo region, Russia) contain trace elements at concentrations far exceeding permissible limits. The objective of this study was to evaluate the effectiveness of chemical and natural materials—lime–dolomite flour, sodium sulfide (Na₂S), wood ash, and granulated chicken manure—for neutralizing acidity and removing potentially toxic levels of dissolved elements. Field experiments involved sequential reagent addition with monitoring of pH, redox potential, and elemental concentrations. The chemical transformations were further interpreted using physicochemical modelling to predict the stability of dissolved and precipitated species. Among the tested materials, Na₂S demonstrated the highest efficiency, precipitating up to 24 mg of metals per gram of reagent and removing more than 92
Groundwater is a critical freshwater resource that underpins India’s agricultural productivity and drinking water security, yet it faces increasing stress from anthropogenic pressures, particularly coal mining. This study assessed mining-induced groundwater level (GWL) decline in the Moher sub-basin of the Singrauli coalfield using ground-based and satellite observations from 2006/2007 to 2020. Satellite analysis revealed a substantial expansion of mining activities, with the mining area increasing from 34.77 km2 in 2007 to 92.47 km2 in 2020. The Mann–Kendall test and Sen’s slope estimator indicated a statistically significant increasing trend (Z = + 5.15) with an average annual growth rate in mining area of 4.22 km2 year⁻1. Normalized difference vegetation index (NDVI) analysis showed a marginal rise in mean vegetation index (0.200 to 0.242), suggesting limited ecological recovery, while persistently low NDVI values over central mining zones indicate continued landscape disturbance. Despite an increasing rainfall trend, GWL exhibited consistent declines near active mines, with depletion rates of 0.63 m year⁻1 (pre-monsoon) and 0.59 m year⁻1 (post-monsoon). The dynamic groundwater reserve declined by approximately 5.1 million m3 within a 77.65 km2 zone of influence, primarily due to mine dewatering. To simulate and predict GWL variation, an artificial neural network (ANN) model was developed using mining area, monsoon rainfall, temperature, and evaporation as predictors. The two-layer feed-forward and nonlinear auto regressive exogenous (NARX) networks demonstrated strong predictive performance, emphasizing the utility of machine learning in quantifying hydrological impacts of opencast mining and supporting sustainable groundwater management and environmental impact assessment (EIA).
This study addresses the critical need for managing water resources in an arid coal mining region by developing a coal-water input–output (IO) model using an improved structural decomposition analysis (SDA) method. The framework, applied to the Qipanjing Coal Mine, China, quantifies the interdependence between coal production and water use. Analysis from 2020 to 2022 identified changes in dust suppression and vegetation irrigation water-use intensity as the dominant factor driving abnormal consumption, with direct water consumption intensity being the primary contributor. The model successfully forecasted water use based on planned production, achieving ≈ 95
In mineral processing, reducing water consumption is a challenge. The investigation evaluated three arrangements (thickener-disc filters, thickener-hydrocyclone, and thickener-hydrocyclone -disc filters) to maximize the dewatering of tailings from the Siriz iron ore processing plant. Testing and sampling were conducted on an industrial scale. The dewatering capacities for the first to third arrangements ranged from 27.3 to 33.1 t/h, respectively. The moisture content of the products was between 24.6 and 26.8
Secondary evaporative mineral precipitates (EMPs) form in underground mines where the nexus between sulfides in country rock, oxygen, and moisture from fracture seepage facilitate their precipitation. Their dissolution rates are rapid, and typically, under conditions with no buffering capacity (e.g. in deionized water) result in acid generation. Twenty EMP samples from the Leeville underground mine (LUG) tested in this way generated acid and high metal concentrations. However, when these materials were dissolved in groundwater at the appropriate ratio for their occurrence in the workings, the acidity generated was neutralized by the groundwater alkalinity. Another source of LUG alkalinity is shotcrete (a cement-based coating on the ribs and back of the 64 km long workings which comprises 68
Hazards such as water inrushes and water-induced rock bursts are major safety challenges in China's coal mines and the occurrence of these disasters is closely related to the deterioration of the mechanical properties of the strata by mine water. However, the damage mechanisms under different hydrochemical conditions remain elusive, especially the mine water-induced deterioration of coal seams in the presence of coal gangue. In this work, the characteristics and possible mechanisms of coal damage are analyzed with different mine water conditions. First, the mineral phase composition and element distribution patterns of coal gangue were characterized by XRD, XRF, and elemental mapping. Then, the ionic constituents of the coal gangue leachates were determined using ICP and IC. Finally, uniaxial compressive strength tests were performed to evaluate the effects of mine water on the mechanical behavior of the coal, followed by a mechanistic interpretation of water-coal interactions. The analyzed coal gangue was primarily composed of minerals such as quartz, albite, and kaolinite, with Al2O3 and SiO2 accounting for ≈ 90
Coal mines in the Mpumalanga Province of South Africa generate large volumes of acid mine drainage (AMD). The AMD is neutralised in high-density sludge (HDS) plants and then treated to potable standard in reverse osmosis (RO) plants. These processes are very expensive, energy intensive, and produce gypsiferous sludges and brines that need to be managed. Irrigation with partially treated or untreated AMD on soils amended with limestone is considered a potential alternative. To test the feasibility of this, two glasshouse pot experiments were conducted, one in the winter of 2023 with barley, wheat, and stooling rye, and the other with sorghum and soybean in the summer of 2023/24. The aim was to evaluate site-specific predictions of fitness for use of these waters using an irrigation water quality decision support system and to determine crop and soil responses to irrigation with untreated acidic waters (pH 2.5 and 3.5) and partially treated mine waters (pH 7.5, 8, and 9). The model predicted rapid soil accumulation of elements for untreated AMD, which was consistent with the pot experiment findings. Even with additional limestone applied to the soils irrigated with untreated AMD to counter the acidity, the soil pH, above-ground biomass, and yield were markedly reduced. Vegetative biomass remained unaffected when partially treated waters were used for irrigation; however, grain yield was slightly reduced. Grains from crops irrigated with highly acidic water exceeded Codex Alimentarius levels for mercury and lead, suggesting consideration of industrial crops that are not consumed, for irrigation with untreated AMD, if yield penalties and environmental impacts of such irrigation are acceptable.
Unregulated small-scale artisanal gold mining (locally known as galamsey) has severely degraded groundwater quality in Ghana, yet long-term contamination trends and sustainable remediation solutions remain understudied. This study analyzed a unique 5-year dataset (2018–2022) from Prestea, Konongo, Bekwai, and Tarkwa, revealing that iron (5.50–5.95 mg/L in Prestea) and manganese (1.45–1.52 mg/L in Prestea) exceeded WHO limits, while lead and mercury remained below detection thresholds. The calculated water quality index (WQI) classified Prestea’s groundwater as “very poor” (WQI > 100) and Konongo’s as “poor” (WQI 76–100), stressing health risks for dependent communities. Water treatment using chitosan nanofibrils (CSFs), a biodegradable, low-cost adsorbent, achieved remarkable removal efficiencies (96
Surface water resources are severely limited in the Ordos Coal Mine Base, northwest China, making groundwater a critical resource for meeting production, domestic, and ecological water demands. Despite its importance, regional− scale assessments of groundwater quality in this area are scarce. To solve this problem, we adopted a comprehensive method combining self− organizing map (SOM) and principal component analysis (PCA) to systematically analyze 69 groundwater samples collected near 14 mining areas in 2023. We focused on analyzing hydrochemical parameters such as the eight major ions, TDS, fluoride ions, and pH, and explored the hydrochemical characteristics and types. Hydrogen and oxygen isotopes were used to identify the main groundwater sources, and groundwater samples in the study area were evaluated for water quality and health risks. The groundwater samples were categorized into three clusters: C1 (SO₄− Ca and Cl− Ca types, primarily associated with high hardness); C2 (a mixture of HCO₃− Na, mixed, and SO₄− Na types, largely linked to elevated fluoride levels); and C3 (predominantly Cl− Na type, correlated with high salinity). Groundwater is primarily recharged by atmospheric precipitation. Drinking water quality predominantly falls into Grade IV to V. Health risk assessments indicate that the groundwater in the region poses a generally moderate level of health risk. This study supports informed groundwater management strategies in the Ordos Coal Mine Base and provides a regional− scale framework for coal mine groundwater quality investigations.
A burnt rock aquifer threatens the safe mining of underlying coal seams. Understanding the height and evolution mechanisms of the water-conducting fractured zone (WFZ) is critical for preventing water inrush disasters and protecting water resources. Focusing on the S1233 panel at the Ningtiaota Coal Mine, where an overlying burnt rock aquifer jeopardizes mining safety, this study comprehensively estimates the WFZ height under completed extraction conditions using empirical and theoretical methods. With two theoretical methods applied based on the key stratum theory, the predicted WFZ height indicated that mining of the S1233 panel had a serious risk of water inrush. Then, a similar material model was established. The characteristics of strata failure, movement, and fracture evolution during working face advancement were systematically analyzed through experimental results. In addition, a critical threshold for water inrush disasters was determined by coupling the relationship between the advance distance and aquifer pressure. Finally, specific water hazard control measures were proposed based on the evolution features of water-conducting fractures. The results of this study provide valuable insights for roof water hazard management in coal mines.
The tailings storage facility iterative simulation model (TSFISM) is a dynamic water-balance simulator that was developed in Microsoft Excel 365®. The TSFISM workbook has a user-friendly interface that incorporates all natural and mine-related inflows and outflows to and from a tailings storage facility (TSF). TSFISM simulates TSF pool stages and free-water volumes by solving iteratively for changes in pool stage and volume at the end of each time step. TSFISM reliably accounts for the dynamic changes in TSF-pool geometry during operations by distributing tailings volumes proportionally by tailings-production mass. Free-water volumes are calculated from frequent bathymetric surveys and tailings production, which negates complexities associated with variably saturated flow, computation of water entrainment, and dry/wet beach evaporation. TSFISM predicts bathymetric surveys at user-specified time intervals for future scenarios. A regression between cumulative tailings production and measured pool-bottom elevations is used to estimate future bathymetries from projected tailings production. TSFISM also dynamically simulates TSF beach and catchment runoff, allowing the beach area, catchment area, and runoff coefficient to vary with time. TSFISM has robust capabilities to simulate a variety of site-specific TSF conditions and can run an unlimited number of water-management scenarios under climatic uncertainty.
As coal mining extends to greater depths, the risk of water inrush from highly confined aquifers increases greatly, which seriously threatens mine safety and critically hampers the safe and efficient extraction of China’s coal resources. This paper focuses on the limestone aquifer water-inrush risks in Taoyuan Coal Mine’s coal seams, presents aquifer-modification control measures, and evaluates the effectiveness of these control measures. The study found that: (1) the average thickness of the aquitard between the limestone aquifer group and the No. 10 coal seam is only 56.4 m; these limestone aquifers could cause water inrushes. (2) The Taiyuan Formation aquifer receives direct recharge from the Ordovician limestone aquifer through connecting water-conducting channels in mining area II2. (3) After grouting was applied to the three-limestone aquifer, the water level elevation decreased from the maximum observed value of − 31.1 m to a range of −125.9 to − 242.7 m, reaching the normal water level. This demonstrates that the grouting effectively eliminated the high-water level anomaly in the treatment area and target stratum, successfully transforming the three-limestone aquifer into a relatively impermeable layer (aquitard). Furthermore, the grouting completely and effectively sealed the water-conducting channels from the Ordovician limestone to the No. 10 coal seam. These results provide useful evidence of coal mine water hazard prevention and control for mines with similar geological conditions.
This study examines how hydrogeological risk assessment (HRA) could be integrated into mine planning in Ghana, marking a shift from simple contaminant inventories to comprehensive evaluations of contaminant transport and associated health risks. Using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 framework, a systematic review of previous peer-reviewed publications was conducted to assess existing research and regulatory frameworks, identify gaps, and propose strategies for sustainable mineral development that safeguard groundwater and public health. Hydrogeological controls across Birimian-Tarkwaian strata influence pollutant mobility, driving acid mine drainage, aquifer contamination, and arsenic-related carcinogenic risks. Comparative analysis of Ghana’s mining regulations against international standards reveals significant deficiencies in mandatory HRA implementation, technical oversight, and enforcement. This study proposes that effective HRA begins with a conceptual model defining contamination sources, migration pathways, and receptors within the hydrogeological setting, followed by an eight-phase process encompassing desk studies, field reconnaissance, soil and infiltration analysis, data collection, risk evaluation, and environmentally informed mine design. The current literature is more focused on contaminant presence rather than transport dynamics and exposure pathways. The study concludes that early integration of HRA into mine planning is essential for preventing groundwater contamination and mitigating health risks. Recommended measures include regulatory reforms mandating pre-operational HRA, establishment of independent technical review panels, enhanced monitoring systems, and formalization strategies for artisanal mining. This work provides a framework for developing context-specific HRA methodologies that balance mineral resource development with environmental and public health protection in Ghana and similar mining jurisdictions.
In northern China, there are a large number of fault-cut karst collapse columns that create risks of water inrush from the Ordovician limestone aquifers beneath the coal seams. In this study, the movement of grouting slurry in a fault-cut karst collapse column and its seepage reduction and structural reinforcement mechanism were symmetrically studied by theoretical analysis, laboratory simulation, and field data verification. The flow of grouting slurry was found to be limited by the column boundary and fault-cut fractures. Under the combined actions of grouting pressure, column weight, and water pressure, the grout slurry mainly flows and diffuses along the column and fault-cut fractures to form a slurry vein skeleton. Specifically, a slurry movement model was established and a theoretical formula was deduced. The 9–6 karst collapse column in the Hemei No. 9 Coal Mine was taken as a research subject. The diffusion distance of the slurry in the column was calculated to be 24 m, less than the field measured distance along the column and fractures (22–34 m). A karst collapse column reinforcement mechanism of grouting was then proposed based on fracture closing and stress enhancement. The laboratory simulation tests suggest that the high pressure grout slurry increased the water pressure and soil pressure in the material simulation model by up to 44.4
