Identification of Mine Water Sources Based on the Spatial and Chemical Characteristics of Bedrock Brines: A Case Study of the Xinli Gold Mine

Water inrush caused by mining below the seafloor is extremely harmful to mine production. Identifying the sources of mine water can help guide mine water management and sustainable mine development. Saline brines were known to be entering the Xinli Mine, a portion of which lies beneath Laizhou Bay, Shandong Province, China. Preliminary classification of the bedrock brines was determined using hydrochemical analysis and the spatial position of the brines. Four bedrock brine types were identified: shallow, middle, middle high-salinity, and deep. The study area was divided into three levels (shallow, middle, and deep) according to the spatial distribution of the brines. Hierarchical-multi-index analysis (HMIA) was used, along with five pairs of chemical indicators (Cl, δ¹⁸O, Mg, Ca, SO₄, Na), to identify the mixing lines for each level. A ternary hybrid model was used to calculate the mixing ratio of mine water from different sources in the shallow sublevels. The bedrock brine classification and water source identification were evaluated by analysis of brine genesis and mixing ratio deviation, respectively. The mixed modes of mine water in the shallow and middle sublevels were seawater-saline water-shallow brine and seawater-saline water-middle brine, respectively. The mixed modes in the deep sublevels were seawater-saline water-deep brine and seawater-saline water-middle brine with a transition between these two modes. Previous studies classified bedrock brine as only one category, and using the mixing ratio greatly improved accuracy. The average proportion of seawater in the mine water has increased over time, but the rate of increased has slowed. In the shallow sublevels, the proportion of seawater in the ? 105 m sublevel was higher than that in the ? 135 m sublevel, but the difference has decreased every year, indicating that the seawater mainly infiltrates by vertical recharge. The mine water samples from the footwall and in the middle of the ? 105 m sublevel were nearly 50% seawater, while the mine water sites on the hanging wall had a relatively low seawater proportion, indicating that the water-conducting fractures were mainly in the footwall.

     

Geological Analysis and Numerical Modeling of Mine Discharges for the Sanshandao Gold Mine in Shandong,China: 1. Geological Analysis

The Sanshandao Gold Mine is one of the largest gold mines in China, and is almost completely surrounded by seawater. Factors such as water-controlling structures and water-bearing zones that developed in the mine were studied, based on geophysical exploration data and hydrogeological investigations of the wells and drifts of the mine. The sources of recharge (seawater, brine from surface runoff, and Quaternary water) were proportionally determined based on ¹⁸O isotopic and water quality data measured for each drainage point in the pits. Appropriate boundary conditions were defined for the recharge source of the seawater and natural runoff brine. The hydraulic connections among the water-bearing zones were also considered. This work was conducted to prepare for future mine development and allowed us to simulate anticipated ground water flow.     

Hydrochemical Analysis of Groundwater in Coastal Coal Mining Areas—A Case Study of the Liangjia Coal Mine,North China

To understand the hydrochemical characteristics and circulation pattern of groundwater in coastal coal mining areas, we analyzed 81 water samples from different water bodies in the Liangjia coal mine (LCM) area using multivariate statistical analysis and hydrochemical methods. The Quaternary groundwater (QW), accumulated water (AW) in the subsidence area, and mine water (MW) in the LCM all exhibit weakly alkaline to slightly saline water chemistry. The dominant cations and anions in the water are sodium (Na⁺) and chloride (Cl^?), reflecting the influence of seawater intrusion. Some ions in QW, AW, and MW exhibited significant annual variations, but Na⁺ and Cl^? concentrations increased with time. The water samples were divided into four categories through cluster analysis: C1 and C2 (bedrock water samples), C3 (water samples prominently affected by seawater intrusion), and C4 (QW and AW in the surface subsidence area). According to the Piper diagram, QW and AW in the surface subsidence area mainly correspond to the Na?Cl type, whereas the MW mainly consists of Na?Cl and Na?HCO₃ types. Factor analysis revealed four main factors: seawater recharge, HCO₃-rich bedrock water, alkaline water, and Quaternary groundwater (QW) with eigenvalues of 4.18, 2.44, 1.22, and 1.19 respectively, which explained 81.98% of the original data information. The comprehensive results of hydrochemical analysis and mathematical statistics indicated that the recharge sources of MW in LCM include seawater, QW, AW, HCO₃-rich bedrock water, and mixed water. Based on regional hydrogeological conditions, a preliminary groundwater circulation model of the coastal coal mining area was constructed. Groundwater generally flows into the Bohai Sea from southeast to northwest, and coal mining has changed the original local groundwater runoff patterns and intensified seawater intrusion.

     

Chemometrics in Ascertaining Hydrogeochemical Characteristics of Coal Mine Discharge vis-à-vis Behaviour of Surface and Groundwater Resources of the Mahan River Catchment Area,Central India

We investigated the hydrogeochemical regime of an AMD-affected coal mining province. 98 water samples were collected over two seasons and analysed for 14 parameters. We attempted to discriminate the sources of variation of water quality using select multivariate techniques: display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis). Most of the groundwater and river water were characterised by shallow freshwater facies (Ca–Mg–HCO₃ type), whereas the samples representative of mine water were of the Ca–Mg–SO₄ type. The mines of the area annually discharge 2901 t of solute loads, ranging from 91 to 1030 t/year. Various molar ratios suggest that dissolution of the silicates associated with the mixing process is the predominant solute acquisition processes that govern the water chemistry of the region besides AMD. The chemometric results indicated that only a few groundwater and river water samples had low pH and elevated total dissolved solids, and these were near the three mines that were affected by AMD. These results substantiate the effectiveness of the mine water treatment measures implemented at the mine sites.

     

Groundwater Source Discrimination and Proportion Determination of Mine Inflow Using Ion Analyses: A Case Study from the Longmen Coal Mine,Henan Province,China

Complex hydrogeological conditions in China’s coal mines have contributed to frequent mine water disasters. A simple and effective method to determine water inflow sources and paths is therefore essential. The Longmen Mine, located in Henan Province, in central China was used as a case study. A Piper diagram and cluster analysis were used to screen the characteristic values of 18 water samples from potential aquifers. A comprehensive fuzzy evaluation of the groundwater ions was carried out to determine the main source of the total mine inflow. Then, based on conservation of ionic masses, a matrix function was established to calculate the groundwater recharge composition. Finally, using measured water inflows for the Cambrian limestone aquifer, the calculated and observed results were compared. The results showed that the Carboniferous Taiyuan Formation limestone aquifer (the L₇ limestone aquifer) accounts for 60.8% of the total mine inflow, while the Cambrian limestone and roof sandstone aquifers account for 34.8 and 4.4% of the inflow, respectively. The normal mine inflow totals about 19,200 m³/day, of which 6,840 m³/day is from the Cambrian limestone aquifer. This agrees well with the calculated value of 6,720 m³/day. Thus, the method is feasible and reliable.     

A Spatial Mixing Model to Assess Groundwater Dynamics Affected by Mining in a Coastal Fractured Aquifer,China

A linear mixing model method based on principal component analysis (PCA) in three-dimensional space was used to assess groundwater dynamics. PCA was performed on a series of hydrochemical datasets collected from 2009 to 2014 (except in 2010). The results of PCA and a prior conceptual model were used to identify the evolution and potential end-members of water. Then, a mixing calculation code was applied to compute the mixing proportions, and the results were used to reconstruct the mixing process. Deviations were evaluated by comparing the computed and measured concentrations of ions. The accuracy of this method was compared to that of a 2D model that was based on only conservative ions and a 3D model developed in this study that does not consider the water’s physical parameters. The results indicated that the method that considered all of the measured ions, stable isotopes, and physical parameters, performed well. Its accuracy was demonstrated by good agreement between its measured and simulated values. The mean values of deviation for δ¹⁸O, δD, K, Na, Ca, Mg, Cl, and SO₄ were 0.26, 0.51, 0.19, 0.08, 0.21, 0.15, 0.05, and 0.08, respectively. Five water sources and their groundwater dynamics were interpreted using this model; the results demonstrated that mining has had a substantial influence on the groundwater flow system in both the vertical and lateral directions. Above a depth of -375 m, freshwater is the dominant source, and its proportions in most sites exceeds 40%. Seawater has reached a depth of ? 510 m, and its maximum proportion of 82% can be observed at 510-2a. Quaternary water recharged the area between F3 and the prospecting line 2230. Its proportion exceeded 45% at most sites. The recharge depth reached ??510 m at most sites and ??600 m at some sites. Calcium-rich and Mg-rich water were distributed above and below ??510 m, respectively. These distinguishing features indicate that induced ground deformation broke through the Quaternary aquifuge and increased the vertical recharge in the tensional zone, while preventing vertical recharge in the compressive zone at the subsidence center.     

布尔台煤矿高氟地下水分布特征及形成机制研究

为研究布尔台煤矿高氟地下水的来源及形成机制，采用数理统计、离子分析等手段，在矿物的溶解沉淀、蒸发浓缩、离子交换和竞争吸附等方面对高氟地下水中F-质量浓度特征及分布规律进行研究。结果表明：布尔台煤矿地下水中C(F-)范围为0.31～11.15mg/L，平均值1.7mg/L。从空间分布上看，高氟地下水主要分布在1～5mg/L范围内，占总样品数的48.48%|从垂向分布上看，高氟地下水主要分布于侏罗系含水层组，其主要补给水源为第四系与第三系孔隙水和侏罗系孔隙、裂隙水。含氟矿物的溶解是高氟地下水的主要控制因素。Ca2+与固相中的Na+、K+发生强烈的离子交换反应，HCO-3的竞争吸附置换出吸附在黏土矿物表面的F-，促使F-富集。     

乌东煤矿地下水水化学特征及其指示

为了研究乌东煤矿煤层顶板含水层之间的水力联系,采用了统计分析、Piper三线图、Gibbs图等方法定性分析了基岩地下水、第四系地下水以及地表水之间的水力联系。利用不同水体的Cl-浓度差异性,计算了相邻含水层之间的水力联系度,定量判别了它们之间的水力联系程度。结果发现,所有地下水样品的pH介于7.1～8之间,都为弱碱性水。随着含水层埋深的加大,地下水TDS逐渐增大,地表水和第四系地下水TDS均低于基岩含水层地下水。基岩地下水、第四系地下水和地表水主要的水化学类型分别为Cl·SO4-Na、HCO3·SO4-Na·Ca、SO4·Cl·HCO3-Na和SO4·Cl·HCO3-Na·Ca。基岩地下水样品受到浓缩作用影响,地表水和第四系地下水受到岩石风化-蒸发影响。同时研究区地下水和地表水中还发生了阳离子反交换作用。第四系地下水和地表水的联系度为0.361,联系程度为中等|第四系和基岩地下水之间的联系度为0.404,联系程度为低。此结果可为后期矿井涌水量预计及防治水工作提供参考依据。     

基于三元混合模型的滨海金矿矿井涌水水源分析

为查明三山岛深竖井建设区域矿井涌水源,选用三元混合模型分析法对三山岛矿井涌水水样进行化验分析,利用矿化度(M)和SO2-4、Mg2+浓度的线性相关性,建立地下矿山涌水源三元混合模型并计算.结果表明:模型方法简单便于操作,能够很好地判断矿井涌水水源构成;矿井涌水在浅部主要来源于海水,其次是基岩卤水,少量第四系水,随深度增...     

Oxygen-18 and Deuterium Fingerprinting of Tailings Seepage at the Sullivan Mine

Stable isotopes of water, ¹⁸O and ²H, were used to fingerprint and quantify the origin and percentage of mixing between tailings pond effluent, seepage collection waters, and background waters at the Sullivan Mill Site, which is located in Kimberley, British Columbia, Canada. The old iron and siliceous ponds are covered by a layer of permeable float rock, which allows meteoric waters to directly infiltrate without undergoing evaporation. In contrast, the east gypsum pond is covered with a layer of till and vegetation, which causes meteoric waters to pond and subsequently be subjected to evaporative processes. The different evaporative environments result in distinctly different isotopic compositions for the waters collected from these sources. The difference in surface cover was used advantageously to identify particular isotopic ratios for the different tailings sources. Water collected from the east gypsum pond is relatively enriched in the heavier isotopes (δ¹⁸O and δ²H), whereas water collected from various locations in the siliceous and old iron pond are relatively depleted in δ¹⁸O and δ²H. The various seepage collection waters were observed to plot at intermediate positions, corresponding either to the old iron pond mixing line, the gypsum pond evaporation line, or somewhere between the two.     

Comparison of Antimony Sources and Hydrogeochemical Processes in Shallow and Deep Groundwater Near the Xikuangshan Mine,Hunan Province,China

Antimony pollution in the groundwater of the Xikuangshan (XKS) antimony (Sb) mine area in China’s Hunan Province has attracted increasing attention. A total of 43 water samples were collected to help understand the hydrogeochemical characteristics, identify the Sb source, and evaluate the water–rock interactions of the Shetianqiao aquifer (SA). The Sb concentrations in shallow and deep SA water samples were 0.1–47.4 mg L^?1 and 0.3–19.2 mg L^?1, respectively. Stibnite oxidation and leaching from arsenic alkali residue mine wastes were the main Sb sources for the shallow SA water, whereas stibnite oxidation and stronger water–rock interaction were the predominant Sb sources for the deep SA water. The higher Sb concentration (>?10.0 mg L^?1) in shallow SA water was predominantly induced by weathering of Sb-bearing minerals, evaporation/concentration effects, and cation exchange, whereas the higher Sb concentration in deep SA water was largely caused by weathering of Sb-bearing minerals, evaporation/concentration effects, ion exchange, and competitive adsorption. These findings provide a more detailed understanding of the geochemical behavior of Sb in groundwater and can be used to develop suitable Sb pollution management strategies.

     

Assessment and Management of Water Resources for a Lignite Mine

A water resource management study was carried out for the proposed exploitation of lignite in Gujarat, India. The main source of water in the region is monsoon rainfall, which averages 567 mm/yr. The mine will be excavated in benches below groundwater level. Depth of water from the surface varies from 2–5 m. Total groundwater available within the leasehold area is 485 m³/day and water demand for mining purposes will be around 120.5 m³/day (25% of the available groundwater). During the monsoon season, an estimated pumping capacity of 236 L/s should taken care of groundwater seepage and rainwater when the maximum excavated area exists. After rehabilitation and backfilling, a water body will be created in the mined out pit, which will act as a water reservoir and enhance groundwater recharge. The mine should not significantly affect the region's water resources as long as the recommendations outlined in this paper are adopted.     

Use of Pb, <Superscript>18</Superscript>O,and <Superscript>2</Superscript>H Isotopes in Mining-related Environmental Studies

Abstract.   An isotopic and geochemical study of surface water and groundwater was undertaken at the Sullivan Mine, a sediment-hosted Pb-Zn massive sulphide deposit with a well-defined homogeneous Pb isotopic composition. The Pb isotopic composition of surface water and groundwater samples from near the mine site define a mixing line between Sullivan Pb and at least one other end member. The ¹⁸O and D isotopic results fall along an evaporation line that shows mixing between water from evaporative sources with water from meteoric sources.     

Environmental Isotope Investigation of Groundwater in the Sarcheshmeh Copper Mine Area,Iran

Precipitation, surface, and groundwater samples were collected during 2009–2010 in the Sarcheshmeh copper mine drainage basin, Kerman Province, Iran. Groundwater samples were collected from both shallow and deep aquifers. All of the samples were analyzed for stable isotopes, deuterium (²H), and oxygen-18 (¹⁸O), and some were analyzed for tritium (³H). The results show a more restricted range of isotopic composition in groundwater samples than in precipitation samples based on the isotopic composition of the precipitation. The isotopic composition of surface and groundwater samples plot to the right of the local meteoric water line of the Sarcheshmeh area and around the evaporation line, indicating that the groundwater within the study area originates from meteoric water that has undergone secondary evaporation before or during recharge. Tritium was below the detection limit in the deep groundwater samples while shallow groundwater samples had tritium concentrations between 1.2 and 1.7 TU, which indicates a longer residence time for deep groundwater.     

Soil Infiltration,Permeability, and Rock Fracturing Assessment to Establish Water Flow Patterns in a Mine with Acid Mine Drainage

The flow of acid mine drainage (AMD) and neutral water were assessed inside an underground mine using a volumetric capacity technique, while water infiltration through the ground was assessed by performing three double ring constant load infiltrometer tests. Measured infiltration velocities were slow to moderate, between 0.036 and 2.07 cm/h. Total rainwater infiltration for the sub-basin was 0.031 hm³/yr. Tests performed on representative rock cores of the stratigraphical column of the area indicated that the permeabilities of the altered schist was 4.73E?10 cm/s, the tuff was 1.47E?09, and the graphitic phyllite was 2.47E?06. A structural analysis was performed inside the mine to assess fractures and faults using the mine plans for three different levels. Three major discontinuity paths were identified. Since the ground and rock permeabilities were low, the large water volumes inside the mine were attributed to these fractures. The results of this study are being used to understand flow patterns in the mine and to optimally locate a water treatment system to control the AMD.     

Geophysical Investigation of the Sulphur Bank Mercury Mine Superfund Site, Lake County, California

Abstract.  Airborne geophysical reconnaissance was used to identify potential flow paths for mercury-rich, acidic water entering Clear Lake near the Sulphur Bank Mercury Mine. Airborne magnetic and electromagnetic conductivity surveys were conducted over a 12.3 km² (4.75 mi²) area that included the Oaks Arm of Clear Lake and the old mine. These surveys identified four magnetic and/or conductive anomalies that may represent groundwater conduits towards or away from the Herman Impoundment. An anomaly that extended from Herman Impoundment through a waste rock dam and into Clear Lake was selected for a more detailed ground electromagnetic conductivity survey. The combined results of the airborne and ground surveys provided a detailed, lateral depiction of conductive zones, the most probable pathways for groundwater flow. These surveys also identified near-surface areas that may contain elevated concentrations of sulfide minerals that weather to produce acid groundwater.     

Evaluating Induced Fractures Between a Large Artificial Lake and an Aquifer-Coal Seam System: A Case Study in Tangshan Coal Mine,China

The hydrogeology of the Tangshan coal mine is extremely complicated. There are at least 20 major faults, with the offset exceeding 50 m. A large artificial lake was created where mining-induced subsidence occurred; it was filled with groundwater pumped from the adjacent aquifers near the coal seams. In addition, there are two nearby rivers that are also believed to have significant groundwater and surface water interactions. Both the river system and the large lake could be a potential threat to a new mining operation in the deep no. 5 coal seam. An in-situ hybrid packer system was designed to measure the thickness of the fracture zone and a 3-D hydrogeological model of the coal seam, associated aquifers, artificial lake, and surface water was established to simulate the groundwater flow field to evaluate the potential impact of induced fractures between the lake and the aquifers and coal seams. The results indicated that the lake has an insignificant impact on the aquifers and coal seams, though it does influence the shallow quaternary aquifer in the study area. Further study is suggested to monitor the groundwater and surface water interactions between the lake and the shallow aquifer system.     

Geochemistry,Hydraulic Connectivity and Quality Appraisal of Multilayered Groundwater in the Hongdunzi Coal Mine,Northwest China

This study assessed the geochemistry and quality of groundwater in the Hongdunzi coal mining area in northwest China and investigated the mechanisms governing its hydrogeochemistry and the hydraulic connectivity between adjacent aquifers. Thirty-four groundwater samples were collected for physicochemical analyses and bivariate analyses were used to investigate groundwater quality evolution. The groundwater in the mine was determined to be neutral to slightly alkaline, with high levels of salinity and hardness; most samples were of SO₄·Cl–Na type. Fluoride and nitrate pollution in the confined aquifers were identified, primarily sourced from coals. Natural geochemical processes, such as mineral dissolution, cation exchange, and groundwater evaporation, largely control groundwater chemistry. Anthropogenic inputs from agricultural and mining activities were also identified in both shallow unconfined aquifers and the deeper confined aquifers, respectively. It was determined that the middle confined aquifer has a high hydraulic connectivity with the lower coal-bearing aquifer due to developed fractures. Careful management of the overlying aquifers is required to avoid mine water inrush geohazards and groundwater quality deterioration. The groundwater in the mining area is generally of poor quality, and is unsuitable for direct human consumption or irrigation. Na⁺, SO₄^2?, Cl^?, F^?, TH, TDS, NO₃^?, and COD_Mn are the major factors responsible for the poor quality of the phreatic water, while Na⁺, SO₄^2?, F^?, and TDS are the major constituents affecting the confined groundwater quality. This study is beneficial for understanding the impacts of coal mine development on groundwater quality, and safeguarding sustainable mining in arid areas.     

Using Environmental Isotopes in a Coal Mine and a Gold Mine to Determine Groundwater Interaction

The use of stable isotope ratios of deuterium (δD) and oxygen (δ¹⁸O) together with major ion data can indicate the origins and movement of surface water and groundwater. During this investigation, hydrochemical and stable environmental isotope sampling were used to determine the interaction between the Karoo aquifer and the Witwatersrand aquifer. It was evident that shallower groundwater samples taken from the Karoo aquifer were affected by annual precipitation and had a short residence time, since their isotopic signature was very close to that of rainfall. By contrast, rainfall events had not recharged the Witwatersrand aquifer and had not significantly contributed to the isotopic fingerprint of the deeper aquifer samples. The Karoo aquifer is generally enriched in both δ¹⁸O and δD; the deeper Witwatersrand aquifer is more depleted in δ¹⁸O and δD. This is explained by their different intake histories and travelling periods. The results also indicate that there is interaction between the Karoo and Witwatersrand aquifer, both where coal mining is present and where it is not.     

Numerical Simulation of Mine Water Inflow with an Embedded Discrete Fracture Model: Application to the 16112 Working Face in the Binhu Coal Mine,China

Properly accounting for the effect of heterogeneity of aquifers and accurately predicting mine water inflow during the mining process is still a challenging problem in China. We developed a stochastic modelling methodology that considers a large range of possible multi-scale fracture configurations and heterogeneous porous rock to predict mine water inflow close to the observed data. The coupled discrete fracture–rock matrix models were built for the Binhu coal mine 16,112 working face with the Monte Carlo method. The models were solved using the embedded discrete fracture model to calculate groundwater inflow from the aquifer beneath the coal seam floor. The calculated results and the observed groundwater inflows in the field agreed well. Sensitivity analysis indicates that groundwater inflow increases with increased fracture length and fracture density. The effect of natural fractures introduces a large uncertainty for the models, due to the existence of long fractures that could act as conduits between the Ordovician limestone and no. 14 aquifers. The results highlight the importance of multi-scale fractures on modeling and simulating flow in the mine area.