Impact of Mining Activities on Groundwater Level,Hydrochemistry, and Aquifer Parameters in a Coalfield’s Overburden Aquifer

Changes in groundwater level, hydrochemistry, and aquifer parameters were studied by following disturbances caused by tunnel excavation in a panel in the Ningtiaota coalfield, northwest China. Temporal changes of hydrochemical compositions were evaluated based on time-series hydrochemical data in three boreholes (J2, J13, and SK8). The time series of hydraulic conductivity and specific storage of aquifers were obtained using the water level response to Earth tides and long-term (from 2014 to 2019) hourly recorded water level data. The results showed that the concentrations of Ca²⁺, HCO₃^?, and TDS in groundwater in borehole J2 decreased sharply following underground tunnel excavation and recovered after six months. Back and forth changes also occurred in the hydrochemical types (HCO₃–Ca?→?HCO₃–Ca–Mg?→?HCO₃–Ca). The excavation caused changes in hydraulic conductivity (about 2 order of magnitudes) and groundwater level (about 3.2 m), possibly by unclogging fractures. This in turn caused hydrochemical changes, such as silicate dissolution and calcite precipitation, possibly due to inflow of dilute water from neighboring aquifers. After the disturbance, the concentrations of Ca²⁺, HCO₃^?, and TDS in groundwater gradually recovered as the aquifer and groundwater levels both tended to recover, possibly due to the reclogging of fractures. This study on the coupled evolution of hydrological processes could enhance our understanding of the effects of mining on aquifer systems.

     

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.     

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.

     

辛置煤矿主要含水层的自由排水柱淋滤实验与水岩作用机理

辛置煤矿石炭系太原组K_2灰岩含水层与奥陶系峰峰组O_2f灰岩含水层水质参数相互重叠,利用传统的判别方法无法对这两个水源进行有效判别。为了解决辛置煤矿水源判别的问题,并揭示该矿4个主要含水层的水岩相互作用机理,对辛置煤矿4个主要含水层的岩芯样品进行自由排水柱淋滤实验。研究结果表明:①岩芯样品含有非矿物相的硫酸盐,4个主要含水层地层同样也含有硫酸盐和石膏矿物,造成淋滤液和灰岩含水层水样均富含硫酸根离子;②K_8,K_3,K_2和O_2岩芯淋滤液中SO_4~(2-)离子当量百分比均超过74%,Ca离子当量百分比均超过40%,所有淋滤液对应的水化学类型均为SO_4-Ca型;③所有淋滤液中阴离子含量大小顺序均为:SO_4~(2-)HCO_3~-Cl~-,K_8,K_3,K_2和O_2f岩芯淋滤液中阳离子含量顺序分别为:CaMgKNa,CaNaMgK,CaMgNaK和CaMgKNa;④K_2灰岩岩芯样品和淋滤液中Mo,Sb,U和Sr含量均高于奥陶系O_2f灰岩岩芯样品及其淋滤液,但Fe离子含量分布规律正好相反,该特征可以作为判别K_2和O_2f灰岩含水层的参考因素。辛置煤矿含水层的水化学特征受岩性、埋藏条件、地下水补径排及水动力条件的控制,含水层实际水质比淋滤液更为复杂多变。K_8砂岩含水层和K_3灰岩含水层的水化学类型分别为HCO_3-Na型和SO_4-Na型,与对应的淋滤液水化学类型差异较大;但K_2和O_2f灰岩含水层的实际水化学类型与淋滤液基本一致。二叠系K_8砂岩含水层中主要的水岩相互作用为溶解斜长石为主,部分区域中可能存在少量的硫酸盐溶解反应。太原组K_3灰岩含水层中的水岩相互作用主要为方解石和白云石矿物的溶解,以及部分硫酸盐和钠盐的溶解反应。太原组K_2灰岩含水层和奥陶系峰峰组O_2f灰岩含水层中主要的水岩相互作用均为方解石、白云石和硫酸盐的溶解,以及局部地段的脱硫酸作用。     

Groundwater Geochemical Variation and Controls in Coal Seams and Overlying Strata in the Shennan Mining Area,Shaanxi, China

Water resource conservation and ecological protection are key coal mining issues in northern Shaanxi Province and the Yellow River Basin. Revealing the characteristics and variation patterns of groundwater quality in the coal series and its overlying aquifers can provide a geological foundation for solving or optimizing these issues. Taking the Zhangjiamao coal mine of the Shennan mining area in northern Shaanxi Province, western China, as an example, water samples were collected for analysis from the: quaternary strata, weathered bedrock, burnt rock, coal series, and coal seam. Test parameters included conventional ion concentrations, total dissolved solids (TDS), and pH. Key water chemistry indicators such as oxidation/reduction index (ORI) and groundwater chemical closure index (GCCI) were used to explain the water quality differences. The Quaternary water, burnt rock water, and weathered bedrock water were dominantly the Ca–HCO₃ type, the coal series water (Yan’an Formation) was dominantly Ca–HCO₃ and Na–Cl types, and the coal seam water was dominantly Na–Cl type. From the shallow groundwater to coal seam water, dissolution and leaching gradually decrease and degree of retention gradually increases. Coal seam water was characterized by high TDS, high GCCI, and low ORI, reflecting a closed hydrogeochemical environment and moderate sulfate reduction. Leaching, salt accumulation, sulfate reduction, and cation exchange jointly control the groundwater chemical characteristics and evolution of the coal series and its overlying aquifers. Salt accumulation and cation exchange reactions of the stagnant coal seam water in the arid and semiarid climates and shallow buried conditions result in increased mineralization; the water quality is vastly different from that of the overlying aquifers, which are dominated by leaching. Groundwater circulation in the coal series and coal seam are of the infiltration–retention type, and the overlying aquifer of the coal series are of the infiltration–runoff type. A comprehensive hydrogeological model was constructed of the Middle Jurassic coal series and its overlying aquifers in the area. The results of this study have implications for the identification of mine water influx sources in the Shennan mining area, and the understanding of controls on the groundwater geochemical variation in Jurassic coal field of western China.

     

Assessment of Hydrogeochemical Processes and Mine Water Suitability for Domestic,Irrigation, and Industrial Purposes in East Bokaro Coalfield,India

Mine water samples collected from the East Bokaro coalfield were analysed to assess suitability for domestic, irrigation, and industrial purposes. The pH of the samples ranged from 6.78 to 8.11 in the pre-monsoon season, 5.89–8.51 during the monsoon season, and 6.95–8.48 in the post-monsoon season. The anion chemistry was dominated by HCO₃^? and SO₄^2?, with minor amounts of Cl^?, NO₃^? and F^?. The Fe concentrations exceeded the maximum permissible limit of the BIS drinking water standard in about 44% of the collected samples. Turbidity, TDS, Fe, total hardness (TH), SO₄^2?, and Mg²⁺ also sometimes exceeded drinking water limits. The TDS, TH and SO₄^2? concentrations of the mine water makes it unsuitable for domestic purposes or for industrial use; high values of %Na, SAR, RSC, and Mg-hazard at certain sites restrict its suitability for agricultural use.     

Environmental Geochemistry and a Quality Assessment of Mine Water of the West Bokaro Coalfield,India

Mine water from the West Bokaro coalfield was qualitatively assessed with respect to domestic and irrigation criteria. Thirty water samples from different mines were collected and analyzed for pH, electrical conductivity, total dissolved solids (TDS), total hardness, major cations, anions, and dissolved silica. The pH of the samples ranged from 6.6 to 8.3 in the post-monsoon season and 6.7–8.4 in the pre-monsoon season, indicating its near-neutral to slightly alkaline nature. TDS ranged from 349 to 1029 mg L^?1 in the post-monsoon season and 499–1458 mg L^?1 in the pre-monsoon season. The spatial differences in TDS reflect the local lithology, surface activities, and hydrology. Ca–Mg–SO₄ and Ca–Mg–HCO₃ were the dominant hydrogeochemical facies; SO₄ ^2? and HCO₃ ^? were the dominant anions and Ca²⁺ and Mg²⁺ were the dominant cations during both seasons. High SO₄ ^2? concentrations are attributed to oxidative weathering of pyrite and gypsum dissolution. Computed supersaturation with respect to dolomite and calcite for most samples may result from the dissolution of gypsum after the water is saturated with respect to the carbonate minerals. Despite moderate to high TDS, total hardness, and SO₄ ^2? concentrations, most of the sampled mine water was of good to permissible quality for irrigation; however, locally higher salinity and Mg restrict its suitability for irrigation at some sites.     

Major Ion Chemistry of Shallow Groundwater in the Dongsheng Coalfield, Ordos Basin, China

A hydrogeochemical study was conducted in the Dongsheng Coalfield, Ordos Basin, China, to identify the mechanisms responsible for the chemical compositions of the shallow groundwater and to document water quality with respect to agricultural and drinking supply standards, prior to mining. Tri-linear diagrams, principal component analysis, and correlation analysis were used to reveal the hydrogeochemical characteristics of the shallow groundwater, and the potential water–rock interactions. In general, the major cations and anions were present at low concentrations, but were relatively higher around Jiushenggong than elsewhere in the study area. Groundwater around Jiushenggong has a long residence time and is also subject to extensive evapotranspiration. The dominant hydrochemical facies are HCO₃-Ca, HCO₃-Na, and mixed HCO₃-Ca·Na·Mg types. Increases in major ion concentrations along the flow path, including Na, Cl, and SO₄, coincide with increases in total dissolved solids. The predominant mechanism controlling groundwater chemistry proved to be the dissolution of carbonates, gypsum, and halite. Cation exchange and mixing with local recharge water are also important factors. The shallow groundwater quality in the study area is suitable for agricultural and drinking purposes.     

基于多方法耦合的矿井突水水源识别模型研究

为快速准确地判别矿井突水水源,减少矿井突水事故带来的危害,以保德矿为例,选取Ca²⁺、Mg²⁺、Na⁺+K⁺、SO₄^2-、Cl^-、HCO₃^-共6种水化学指标作为判别指标,通过分析各含水层水化学特征,确定了各含水层代表水样,以此为基础建立了耦合主成分分析-离群值检验-回归填补法-贝叶斯判别法的矿井突水水源判别模型,并将模型判别结果与PCA-Bayes模型判别结果做出对比。结果表明:保德矿采空区、二叠系砂岩含水层、石炭系砂岩含水层、奥灰含水层的水质类型分别为HCO₃-Ca·Na·Mg型、HCO₃-Na型、HCO₃-Na型和HCO₃·SO₄-Ca·Na·Mg型;保德矿水样主成分为Ca²⁺、Mg²⁺、Na⁺+K⁺     

Hydrogeochemical Processes and Inverse Modeling for a Multilayer Aquifer System in the Yuaner Coal Mine,Huaibei Coalfield,China

Coal mining can dramatically change hydrogeological conditions and induce serious environmental problems. Fifty groundwater samples were collected from the main aquifers in the Yuaner coal mine (Anhui Province, China). The results show that the main hydrogeochemical processes in the mine include dissolution, precipitation, pyrite oxidation, desulfurization, and cation exchange. The Neogene porous aquifer is affected by groundwater flow conditions; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, and cation exchange. The Permian coal measure’s fractured sandstone aquifer was confirmed to be controlled by the region’s geological structure; its main hydrogeochemical processes are desulfurization and cation exchange. The Carboniferous Taiyuan limestone aquifer was determined by both groundwater flow conditions and regional geological structure; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, pyrite oxidation, and cation exchange. Additionally, hydrogeochemical inverse modeling of the groundwater flow path confirm the hydrochemistry results and principal component analysis.

     

多元对应分析法在潘一煤矿地下水化学特征分析中的应用

为分析矿井充水水源水质特征,为判别突水水源提供理论依据,将多元对应分析方法应用于潘一煤矿各含水层水质特征区分以及同一含水层内垂向上水质变化的分析,并将分析结果和Piper图进行比较,结果表明：多元对应分析法可以分析水样样本之间、水质指标之间和样本与水质指标之间的关系,取得了比Piper图更好的分析效果;该方法很好地解释了矿区充水含水层的水质特征以及二叠系煤系砂岩裂隙水受新生界下含水的影响及其水质变化特征;分析结果与矿区水文地质条件相吻合.     

Contribution of Solutes to Density Stratification in a Meromictic Lake (Waldsee/Germany)

Density differences are the key parameter for stratification stability. We used data from the iron-meromictic Waldsee, Germany, a lignite mine pit lake, to quantify the contribution of single solutes to water density and analyzed the density gradient. Iron meromictic lakes maintain their density gradient through chemical reactions. Hence, quantifying the contributions of separate solutes is essential for understanding the entire process. Based on solute concentrations and literature values of partial molal volumes, substance specific density contributions were quantitatively evaluated. Then, by direct measurements of the density of IHSS Waskish peat fulvic acid, we quantified the density contribution of dissolved organic carbon (DOC). While several solutes contributed to the density throughout the water column, only those substances that occurred at higher concentrations in the anoxic monimolimnion than in the oxic mixolimnion were crucial to sustaining the density difference between the two layers. In Waldsee, the density difference between monimolimnion and mixolimnion was attributed to dissolved Fe²⁺ (0.23?g/L, resulting in a 45?% of the density difference due to solutes) and to the carbonate system (HCO₃ ^?, about 0.16?g/L and CO₂, 0.03?g/L) while Ca²⁺ and DOC delivered only a small contribution. In summer, total density differences were dominated by temperature differences; during winter, solutes sustained meromixis. Finally, we present a complete list of specific density fractions for basically all of the density-relevant substances in fresh waters.     

采动影响下井田主要充水含水层水化学环境演化分析

为了揭示采动影响下井田主要充水含水层水化学的时空演化规律,运用多元统计学中的主成分分析法对淮北矿区任楼井田不同时期的“四含”、“煤系”、“太灰”与“奥灰”水样的常规水化学数据（K ++Na +,Mg 2+,Ca 2+,Cl -,SO2-4,HCO-3与CO 2-3）进行分析,确定了方差贡献率较大的第一与第二主成分,分别代表“脱硫酸”作用和“硬化”作用,并揭示包含于其中的“咸化”过程,进而得到各主要充水含水层水样主成分得分的时空分布。研究成果表明：任楼井田“四含”水化学环境受控于基岩面,采动影响大;“煤系”水化学环境受断层与岩溶陷落柱控制,采动对其影响不大;“太灰”水化学环境受断层与岩溶陷落柱控制,采动影响大;“奥灰”水流交替快,水化学环境受采动影响小。井田主要充水含水层水化学环境的时空演化除了与自身所处的地质背景有关外,采动是一个不可忽视的影响因素。     

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.     

Geochemical and Mineralogical Characterization of a Pyritic Waste Pile at the Anjir Tangeh Coal Washing Plant, Zirab, Northern Iran

Coal washing at the Anjir Tangeh plant, in Zirab, northern Iran, has produced more than 1.5 Mt of coal wastes. These waste materials were geochemically and mineralogically characterised to guide development of an appropriate remediation scheme. Three vertical trenches up to 4 m deep were excavated from the coal waste pile surface and 25 solid samples were collected at 0.5 m intervals. The samples were analysed for total concentrations of 54 elements, paste pH, SO ₄ ^?2 , CO ₃ ^?2 , and HCO₃ ^?. The lowest pH values were measured at a depth of 0.3 m. The upper portion (1 m) of one profile was moderately oxidised, while oxidation in the other two profiles did not extend more than 0.8 and 0.5 m beneath the pile surface. The waste piles have low acid-producing potential (15–21.87 kg CaCO₃/t) and high values of acid-neutralizing potential (0.06–96.2 kg CaCO₃/t). Fe, Al, S, Na, Mn, Pb, Zn, Cd, and Ag increased with increasing depth, while Mo, Sr, Zr, and Ni decreased with increasing depth. The results show pyrite oxidation at depth and subsequent leaching of the oxidation products. Mn, Zn, Cu, Pb, Ag, and Cd are the most important contaminants of concern at this site.     

Hydrogeochemical Evolution of an Ordovician Limestone Aquifer Influenced by Coal Mining: A Case Study in the Hancheng Mining Area,China

Statistical analysis was used to study the hydrogeochemical evolution of an Ordovician limestone aquifer group in the Hancheng mining area. Before mining, the groundwater flowed from northwest to southeast, the water type was primarily SO₄–HCO₃, and was mainly controlled by the tectonic structure and the specific hydrogeological conditions. After 40 years of mining, two large groundwater depression cones had formed, centered on the Sangshuping and Xiangshan coal mines in the north and south zones, respectively. The groundwater dropped by ≈?20 m in the center of the depression cones due to over-exploration and mine water inrush, which changed the groundwater flow field significantly. Both the total dissolved solids and the concentrations of major ions increased 2.3- to 4.7-fold, and the water type changed to SO₄–Cl. The saturation indices (SI) of the minerals along the two simulated paths both increased, indicating that the groundwater would dissolve minerals as it flowed, which verified the groundwater flow field. Groundwater quality deteriorated due to a mixture of old acidic pit water and hypersaline water intruding from the deep district. When studied vertically, the concentrations of major ions and SI of calcite and limestone increased, due to the limited cycling of water from shallow to deep. The coincidental Ca²⁺ and Mg²⁺ increases were caused by calcite-replacing dolomitization reactions. To summarize, long-term coal mining adversely affected the area’s groundwater flow field and hydrogeochemical evolution, and effective action should be taken to prevent the Ordovician groundwater from continuing to deteriorate.     

华北隐伏型煤矿区地下水化学及其控制因素分析——以宿县矿区主要突水含水层为例

采用宿县矿区主要突水含水层四含、煤系、太灰地下水样常规离子(K~++Na~+,Ca~(2+),Mg~(2+),Cl~-,SO_4~(2-),HCO_3~-,CO_3~(2-))、pH值、TDS等数据,利用离子组合比和主成分分析方法探讨了水化学成分的形成机制,进一步通过研究主成分荷载得分与水化学类型的空间分布规律,分析了矿区地下水水化学形成及其控制因素。研究结果表明:宿县矿区主要突水含水层水化学数据差异是不同地下水化学成分形成作用的综合反映,其中煤系以阳离子交替吸附或脱硫酸作用最为显著,而四含、太灰以黄铁矿氧化或碳酸盐、硫酸盐溶解作用最为显著。宿县矿区采矿活动与地质背景条件不同程度地影响了主要突水含水层水化学成分形成作用与水化学类型的空间分布,其中四含主要受采矿活动控制,煤系主要受断裂(层)控制,太灰主要受采矿活动、断裂(层)与褶皱控制。     

Use of Marine Waste Extract as a Nitrogen Source for Biological Sulfate Reduction: Development of a Suitable Alternative

Marine wastes extract (MWE), prepared from marine organic wastes, was used to develop an alternative nitrogen source for sulfate-reducing bacteria (SRB) in environments like acid mine drainage that are acidic in nature and contain high levels of sulfate and dissolved metals. The MWE contains 13.95 g L^?1 of nitrogen, and other micronutrients like K, Na, P, S, Ca, Fe, Mg, Mn, Zn, Co, Cu and Ni, and has a C/N ratio of 0.107. A modified SRB medium (MSRB) was developed by replacing the commercial nitrogen source of standard SRB growth medium with MWE. MSRB was compared with modified Postgate B, Postgate B, and Widdel and Pfennig media, which contained bactopeptone and NH₄Cl, as nitrogen sources. Results showed that the growth media could support a total microbial population of 2.8 × 10¹²–6.2 × 10¹² cells mL^?1 with 96, 80, 92.5, and 65 % SRB in MSRB, Postgate B, modified Postgate B, and Widdel and Pfennig media, respectively. The sulfate reduction efficiency was 97, 87, 72, and 68 % at reduction rates of 12.41, 11.10, 4.35, and 8.8 mg L^?1 h^?1, respectively, for the same media. We conclude that MWE could be a cost-effective substitute for commercially available nitrogen sources for SRB for large-scale treatment of sulfate-rich wastewater.     

和顺南部矿区水文地质条件与矿井涌水量预测

在和顺地区水文地质资料的基础上,根据抽水试验结果,划分出三个主要的含水层组,得出影响煤层3、15煤安全开采的含水层为二叠系K10、K9、K8、K7砂岩和奥陶系K4、K3、K2灰岩;通过分析水文地质条件,发现矿井充水水源主要为受到大气降水补给的山西组、上石盒子组和太原组的含水层,以及采空区积水,采动裂隙为主要的导水通道,陷落柱、断层封闭性较好;得出该区3、15煤的水文地质类型分别为二类一型和三类一型,进一步选择采用大井法预测出矿井最大涌水量为134.23 m3/h。     

Pyrite Weathering in Reclaimed Shale Overburden at an Oil Sands Mine near Fort McMurray,Canada

Saline-sodic shale overburden associated with oil sand mining is a potential source of salt release to surface water and groundwater and can lead to salinization and/or sodification of reclamation covers. Weathering of shale overburden due to oxidation of sulphide minerals within the shale leads to sulphate (SO₄ ^2?) production and increased salinity. The controls on the rates of weathering of a shale overburden dump in the oil sands region of northern Alberta were determined from soil chemistry sampling and in situ monitoring of pore gases (O₂, CO₂, CH₄) in three shallow profiles (1.9–4.45 m deep) and one deep (25 m deep) profile under reclamation covers of varying thickness. Oxidation, defined by the depth over which O₂ concentrations were depleted, reached depths of approximately 1.1 m under the reclamation soil covers over a 6 year period after dump placement. Calculations of SO₄ ^2? production rates and weathering depths were consistent with numerical simulations of the diffusion and subsequent consumption of atmospheric O₂ in the overburden. The rate of SO₄ ^2? production during the 6 year weathering period estimated from direct measurements of solids chemistry ranged from 0.70 to 8.3 g m^?2 day^?1. The rates calculated from the oxygen diffusion models were within that same range, between 1.6 and 4.1 g m^?2 day^?1.