Coal Mine Water Research Articles

Mutual Effects of Temperature and Microorganisms on the Chemical Characteristics of Coal Mine Drainage

Coal mining activities produce coal mine drainage which becomes a potential pollutant of regional groundwater. The temperature and microbial community in aquifers and rock formations change with coal mining depth increases. While the influence mechanisms of temperature and microorganisms on the hydrochemical characteristics of mine water are poorly understood. This study investigated a typical minefield in north China and performed the water–rock (coal) incubation experiments to explore the effect of temperature and microorganisms on the chemical characteristics of mine water. Hydrochemistry type of coal mine water in the goafs and main water-filled aquifers of Xinjulong coal mine was the SO4–Na type. Proteobacteria and Firmicutes were the main bacterial phyla in the coal mine water. The increasing closure time of goafs decreased SO4 2− concentration and increased the microbial diversity in mine water. The 28-day incubation experiments found Na+ and SO4 2− slightly increased by 5.13 and 6.67%, respectively, and HCO3 − decreased by 14.33% when the temperature rose by 10 °C. The Shannon index of the bacterial community in water–coal system increased by 6.7% and the relative abundance of Hydrogenophaga decreased by 22.7%, while that of Thiobacillus increased by 31.56%. The microbial activities decreased Na+ and SO4 2− by 2.31 and 4.95%, respectively, but increased HCO3 − by 7.59%. The functional prediction showed the microorganisms undergone sulfur conversion reactions and affected the dissolution of ions in mine water. The results were crucial for understanding the mutual effects of temperature and microorganisms on the hydrochemical characteristics of coal mine water.

Effect of Polydopamine/Sodium Dodecyl Sulfate Modified Halloysite on the Microstructure and Permeability of a Polyamide Forward Osmosis Membrane.

Mine water cannot be directly consumed by trapped people when a mine collapses, so it is difficult for people to carry out emergency rescues to ensure their safety. Therefore, a water bag made of a forward osmosis (FO) membrane has been designed that can efficiently filter coal mine water to meet the urgent needs of emergency rescue. Before interfacial polymerization (IP), sodium-dodecyl-sulfate-modified halloysite (SDS-HNT) was added to an MPD aqueous solution to prepare an SDS-HNT polyamide active layer, and then the prepared membrane was placed into a polydopamine (PDA) solution formed by the self-polymerization of dopamine and a PDA/SDS-HNT composite film was prepared. The results showed that the original ridge-valley structure of the polyamide membrane was transformed to a rod-, circular-, and blade-like structure by the addition of SDS-HNTs. Subsequently, a dense PDA nanoparticle layer was formed on the modified membrane. The polyamide/polysulfone forward osmosis membrane modified by co-doping of PDA and SDS-HNTs displayed both the best water flux and rejection rate, confirming the synergistic effect of compound modification. Therefore, the high-performance permeability of the polyamide membrane modified by SDS-HNTs and PDA provides great convenience for the emergency filtration of coal mine water, and also has potential applications in wastewater treatment and seawater desalination.

Characterization of Former Coal Mining Ponds (voids) and Water Management System Planning

Characterization of Former Coal Mining Ponds (voids) and Water Management System Planning

The occurrence of elevated δ34S in dissolved sulfate in a multi-level coal mine water system, Glasgow, UK

Stable isotopic compositions of δ18O, δ2H and dissolved sulfate δ34S in water from abandoned and flooded coal mines are used to interpret the water's and solutes' origin and interactive history. These isotopic ratios have been determined in mine water from a shallow (<100 m) series of overlapping coal mine workings at the UK Geoenergy Observatories Glasgow Geothermal Energy Research Field Site (UKGEOS GGERFS). Comparison has been made between dissolved sulfate δ34S of water in mined Carboniferous coal-bearing strata, that of water which had interacted with equivalent unmined strata, and δ34S in sulfide-bearing minerals (pyrite) in the host sedimentary rocks and local evaporite (gypsum) of the Lower Carboniferous Ballagan Formation. δ18O and δ2H confirm a meteoric origin for coal mine waters. The δ34S arithmetic mean and standard deviation of the pyrite (+5.0 ± 15.5‰) and water from unmined strata (+0.3 ± 2.1‰) were found to be similar, whereas the mine water exhibited elevated isotopic values (+20.3 ± 1.1‰), plotting closer to that of modern-day seawater (+21.2‰) and Ballagan Formation gypsum (+18.9 ± 0.5‰). Whilst the origin of dissolved sulfate in the mine water remains unclear, it is unlikely to be wholly due to simple pyrite oxidation. Influence of evaporite dissolution, fractionation associated with microbial sulfate reduction, and mixing with saline formation waters of marine, evaporitic or of another origin, cannot be ruled out.

Dissolved sulfate δ34S and the origin of sulfate in coal mine waters; NE England

Coal mine waters have been sampled during a reconnaissance study in the East Midlands, South Yorkshire and Tyneside areas of England. Almost all the mine waters had similarδ18O andδ2H concentrations, indicating a derivation from Holocene recharge (average of −7.9 and −54‰, respectively, excluding two outliers). Most mine waters emerging by shallow gravity drainage have dissolved sulfateδ34S levels of &lt;+10‰, suggesting a derivation of sulfate from the oxidation of pyrite. Deeper mine waters, pumped from boreholes or shafts, tended to be more saline with dissolved sulfateδ34S levels of &gt;+14‰ and, in two cases, &gt;+30‰. The sulfate in these latter waters cannot be readily explained as deriving from pyrite oxidation. Alternative hypotheses (evaporitic or marine brines, evaporite dissolution or partially-closed-system microbial sulfate reduction) can be invoked as explanations. A more general hypothesis proposes that deep groundwaters/mine waters can be regarded as saline ‘sinks’, whose sulfateδ34S concentration is controlled by a dynamic equilibrium between rates of sulfate mobilization from various sources and sulfate removal by precipitation or microbial reduction.Supplementary material: Supplementary Material A (a detailed description of sample sites and results) and Supplementary Material B (locations of sample sites) are available athttps://doi.org/10.6084/m9.figshare.c.6418981

Optimization Model of Water Resources Allocation in Coal Mine Area Based on Ecological Environment Priority

It is of great practical significance to explore the efficient water resources allocation model based on ecological environment priority in coal mine areas. In this paper, an open-well coal mining area is selected as the study area. Firstly, the changing characteristics of water supply and demand balance in the study area during 2015–2020 are studied, and the defects of the existing water resources allocation mode are analyzed. Then, considering the economic, social, and ecological factors, a multi-objective model of optimal allocation of water resources was established. Finally, the optimal water resource allocation scheme was obtained by using a particle swarm optimization algorithm. The results indicate that both the water supply and consumption in the study area decreased from 2015 to 2020. The utilization rate of fresh water also has been declining year by year, and the water source structure tilted to the reclaimed water resources. Among water users, coal mining water consumption is the highest, while ecological water consumption is the lowest. There is still a large amount of recycled water that has not been reused, resulting in a waste of water resources. The optimal water resources allocation scheme shows that the allocation scheme meets the needs of each water user within the limits of the water supply source. The sewage reuse rate reached nearly 100%, which realized the maximum utilization efficiency of water resources. The utilization rate of fresh water was 29.94%, and the dependence on freshwater resources was reduced. Reclaimed water accounts for 77.8% of the total water consumption. The water source structure has been optimized to realize efficient use of water resources.

ANALISIS PENURUNAN KADAR LOGAM BESI (Fe) &amp; MANGAN (Mn) DENGAN PENGGUNAAN KOAGULAN TERHADAP AIR TAMBANG BATUBARA PT. ADARO INDONESIA

The purpose of writing this study is to analyze the influence of coagulants to reduce the levels of dissolved metals Iron (Fe) &amp; Manganese (Mn) from coal mine water The place of the study is in the operational area of the PT. Adaro Indonesia in Tabalong and Balangan Regencies, the object of the study of mine water samples was taken at the Settling pond (SP) X inlet located in the Wara mine area. This research was conducted with an experimental method, namely the Jar Test test with an experimental design compiled in a Non-Factorial Group Randomized Design (RAK) consisting of 6 (six) treatments with 3 repetitions. The analysis method carried out to determine the influence of coagulants on the decrease in Fe and Mn metal levels is to use the Anova and Tukey (BNJ) analysis method. The results of this study from all the treatments that have been carried out on coagulants in the study, the coagulants that have the greatest influence in reducing Fe metal levels are the use of coagulant Y with a combination of treatments with an increase in water pH (caustic soda Y) combined with fast and slow stirring (D1) of: 0,002 mg/L, treatment with an increase in water pH (caustic soda Y) combined with rapid stirring (D2) by: The 0,002 mg/L data analysis with the anova and tukey BNJ tests differed from other treatments. The coagulant that has the greatest influence in reducing Mn metal levels is the use of coagulant Y with a combination of treatment with an increase in water pH (caustic soda Y) + auxiliary coagulant Y combined with rapid mixing (F2) of: 2,509 mg/L, treatment with an increase in water pH (caustic soda Y) + auxiliary coagulant Y combined with slow mixing (F3) of: 2,518 mg/L.

Effects of water-coal interactions on coal mine water quality in China: a lixiviation experiment and actual water quality investigation.

Water-coal interactions are dominant factors that affect water quality in coal mines. Using lixiviation, the effects of water-coal interactions on pH, salinity, and hazardous elemental enrichment in coal mine water and associated trends were simulated and analyzed. The salinity and hazardous element contents were low in the alkaline solution filtrate. However, the salinity and contents of hazardous elements (As, Cr, Zn, Cu, Mn, Co, Ni, Cd, Pb, U, and Be) in acid solution filtrate increased significantly with a decrease in pH. The pH of the solution filtrate was affected by the mineral composition of the coal, wherein the pyrite content could generally determine the pH. In addition, the spatial distribution and utilization potential of coal mine water quality in China was determined based on water quality data surveys. For water-deficient regions in northern China, particularly in the northwest, the local mine water had high salinity, a high pH, and a low content of hazardous elements; therefore, the reuse of mine water for water consumption is feasible. Conversely, the mine water in the southwest region had high salinity and a low pH and was enriched in harmful elements with potential ecological and health risks. The actual water quality characteristics of the coal mine water matched the results of the laboratory simulation analysis, confirming the effect from water-coal interactions. This work provides a reference for understanding the determinants of coal mine water quality and the potential for water environment protection.

Analysis of Iron (Fe), Manganese (Mn), and pH of Coal Mine Acidic Water in Aceh Province

One of the coal mining corporations is in charge of environmental management, which includes managing water resources One of the coal mining corporations is in charge of environmental management, which includes managing water resources. The management of coal mine water that has the potential to become polluted water can be processed into fresh water in a sustainable manner. This indicates that acidic water from coal mines is still handled as waste that must be addressed once more. According Ministry of Health Regulation No. 416 1990 on Water Quality Requirements and Monitoring (Indonesian Government Regulation Ministry of Health related to water quality requirements and water quality monitoring), the purpose of this study is to evaluate the viability of coal mine acidic water quality in comparison to Fe (iron), Mn (manganese) ions, and pH parameters as fresh water. According to the findings of this study into acid mine drainage, the pH of the water in nine study areas in Pucok Reudeup Village, a former coal mining region, is low. The findings of this study on acid mine drainage demonstrate that the pH of the water at nine research sites in Pucok Reudeup a village near a disused coal mine. In nine research locations in Pucok Reudeup Village, a former coal mining area, the pH of the water did not exceed the established freshwater quality requirements (pH water below 6.5 - 9), according to the findings of this acid mine drainage study. Fe parameters that fulfilled the quality requirements were only present at five research sites. High iron concentrations result from Fe 2+ or Fe 3+ ions that cannot obtain oxygen from the environment as well as from the stripping of soil and rocks that are predominately composed of iron minerals, necessitating further management such as aeration. All study sites' Mn (manganese) parameters continue to fall short of the quality requirements outlined in No. Minister of Health Regulation 416 of 1990 Requirements on water quality No. Minister of Health Regulation 416 of 1990 Requirements on water quality and monitoring, that is, always exceeding the quality standard by 0.5 mg/L, except for stations 4, 5 and 6 There are 3 locations of Mn (manganese). In general, it can be concluded that the Fe and pH parameters of the study area still do not meet the freshwater quality standards. While Mn partially meets freshwater quality standards atstations (4, 5 and 6). Stations 1, 2, 3, 7, 9 are always higher than fresh water quality standards. The problem of acid mine drainage requires environmentally friendly water treatment.

Mechanism of Changes in Goaf Water Hydrogeochemistry: A Case Study of the Menkeqing Coal Mine.

Goaf water in mining areas is widely found in China's coal mines. To clarify the hydrogeochemical characteristics of goaf water and the influence mechanism of water-rock interaction and further reveal microbial action on the formation of goaf water quality, the goaf water in the Menkeqing coal mine was taken as the object, and physical modeling was used to simulate the process of the real goaf changing from an oxygen-sufficient environment to an anoxic environment with the rise of groundwater level in this work. The experimental results showed that the water-rock interaction in the goaf was mainly the dissolution-precipitation of minerals in the rocks of the caving zone and fracture zone, cation exchange, and oxidation of pyrite in the coal layer. The primary sources of Na+ and K+ in the goaf water were the dissolution and reverse ion exchange of silicate minerals such as albite and potassium feldspar, while Ca2+ and Mg2+ mainly from the dissolution of minerals such as calcium feldspar, calcite, and chlorite. The oxidation of pyrite in coal was the main reason for the increase in SO42- concentration, the enhancement of reduction, and the decrease in pH and DO (dissolved oxygen) in the goaf water. Relative abundance of sulfate-reducing bacteria (SRB) in goaf (e.g., Desulfosporosinus, Desulfobacterium, etc.) increased gradually, inhibiting the increase in SO42- concentration in goaf water through the devulcanization of SRB. The inverse hydrogeochemical modeling was performed using PHREEQC for two stages of the simulation experiment: 0-30 days and 30-300 days. The simulation results show that the water-rock action in the formation of goaf water mainly occurred in the simulation experiment's early stage (0-30 days), and the mineral dissolution is dominant throughout the experimental stage. The results of the study provide a theoretical reference for the prediction of highly mineralized water pollution in goaf and its prevention and control.

Impacts of high-quality coal mine drainage recycling for replenishment of aquatic ecosystems in arid regions of China: Bacterial community responses

Coal mine water is usually recycled as supplementary water for aquatic ecosystems in arid and semiarid mining regions of China. To ensure ecosystem health, the coal mine water is rigorously treated using several processes, including reverse osmosis, to meet surface water quality standards. However, the potential environmental impacts of this management pattern on the ecological function of receiving water bodies are unclear. In this study, we built several microcosm water ecosystems to simulate the receiving water bodies. High-quality treated coal mine drainage was mixed into the model water bodies at different concentrations, and the sediment bacterial community response and functional changes were systematically investigated. The results showed that the high-quality coal mine drainage could still shape bacterial taxonomic diversity, community composition and structure, with a concentration threshold of approximately 50%. Moreover, both the Mantel test and the structural equation model indicated that the salinity fluctuation caused by the receiving of coal mine drainage was the primary factor shaping the bacterial communities. 10 core taxa in the molecular ecological network influenced by coal mine drainage were identified, with the most critical taxa being patescibacteria and g_Geothermobacter. Furthermore, the pathway of carbohydrate metabolism as well as signaling molecules and interactions was up-regulated, whereas amino acid metabolism showed the opposite trend. All results suggested that the complex physical-chemical and biochemical processes in water ecosystems may be affected by the coal mine drainage. The bacterial community response and underlying functional changes may accelerate internal nutrient cycling, which may have a potential impact on algal bloom outbreaks.

Optimization of experimental conditions of microbial desulfurization in coal mine using response surface methodology.

To reduce the risk of spontaneous combustion during coal storage and transportation, microbial desulfurization technology is used to reduce the content of inorganic sulfur in coal. A strain of Aciditithiobacillus ferrooxidans was purified from coal mine water in Datong, Shanxi Province, and its desulfurization test conditions were optimized. Taking the inorganic sulfur removal rate of coal as the response value. The Plackett-Burman design method was used to screen the main factors affecting the response value. And the response surface method was used to establish the continuous variable surface model to determine the interaction between the factors. The results show that the three main factors affecting the response value and their significance order are temperature > coal particle size > desulfurization time, and the interaction between temperature and coal particle size has the greatest effect. When the temperature is 29.50°C, the coal size is 100 mesh, and the desulfurization time is 11.67days, the desulfurization effect is the best, and the removal rate of inorganic sulfur can reach 79.78%, which is close to the predicted value, and the regression effect is wonderful.

Study on water inrush pattern of Ordovician limestone in North China Coalfield based on hydrochemical characteristics and evolution processes: A case study in Binhu and Wangchao Coal Mine of Shandong Province, China

Groundwater plays a critical role in the mining areas, providing water for human activities and the growth of animals and plants, but also the main object of mine water disaster prevention. A study on hydrochemical characteristics and evolution in the process of mine water inrush has important practical significance for accurately identifying mine water inrush sources. In this study, the water samples of Ordovician limestone water, the 14th limestone water, and inrush water in Binhu and Wangchao Coal Mines of Tengxian Coalfield were collected. The water samples were compared and analyzed to reveal the variation characteristics of major ion concentration and hydrochemical evolution mechanism during floor cracking-Ordovician limestone water inrush. The results indicated that the type of Ordovician limestone water is Cl-Ca type, the 14th limestone water is Mixed type, and all inrush water is Cl-Na type. Na+(K+) is negative with Ca2+ and Mg2+, while Ca2+ is positive with Mg2+. Hydrochemical analysis showed that the degrees of cation exchange in groundwater are inrush water > the 14th limestone water > Ordovician limestone water, and the average cation exchange contents △C(K++Na+) c are 30.85 meq/L, 9.90 meq/L, and 8.10 meq/L, respectively. Cation exchange significantly changed the Ca2+(Mg2+) and Na+(K+) levels in an aqueous solution during water inrush from Ordovician limestone. The concentration of Ca2+(Mg2+) decreased, while the concentration of Na+(K+) increased significantly and finally formed inrush water with high Na+(K+) and low Ca2+(Mg2+) levels. The saturation index (SI) indicated that the minerals CaCO3, CaMg(CO3)2, and CaSO4.H2O are in oversaturation, the cation exchange results in the decreasing Ca2+(Mg2+), and the SI value is limestone water > the 14th limestone water > inrush water. The cluster analysis (CA) results also showed that considering the effect of cation exchange on the ions concentration of groundwater, the Ordovician limestone, the 14th limestone water, and inrush water samples have the same source in the study area. Overall, The cation exchange significantly affects groundwater ion concentration in the process of Ordovician limestone water inrush. These findings provide a new insight into the hydrochemical evolution mechanism of groundwater and reveal the evolution pattern of Ordovician limestone water inrush in the North China Coalfield.

Microseismic Precursors of Coal Mine Water Inrush Characterized by Different Waveforms Manifest as Dry to Wet Fracturing.

Microseismic monitoring systems have been widely installed to monitor potential water hazards in limestone of the coal floor. The temporal and spatial distribution of rock fracture-induced microseismic events can be used as early warning indicators of potential water inrush from the coal floor. We established a microseismic monitoring system in the working face of Wangjialing coal mine. Besides traditional fluid-independent rock fracture-induced microseismic waveforms, fluid-dependent hybrid-frequency microseismic waveforms also play important roles in determining the microseismic precursors of water inrush. Hybrid-frequency microseismic waveforms have a sharp P wave and no obvious S wave phase. We infer that the first high-frequency signal is caused by the brittleness of the rock in the floor under the influence of the water pressure. The second low-frequency signal is caused by the water oscillations in the fractures. These hybrid-frequency waveforms represent the development of fracturing. In addition, the lifting height of the complete aquiclude above the confined water is very limited, and the water inrush from the floor is often closely related to these hidden faults. Therefore, the activation signal of hidden faults in the working face of coal mining can be monitored to effectively warn about the water inrush from the coal seam floor caused by faults. By analyzing different microseismic events, the monitoring and early warning of water disaster in the coal mine floor can be improved. This will help in taking measures in advance within the mine to ensure personnel safety and to reduce property losses.

TEMPORAL AND SPATIAL CHANGE DETECTION OF ECOLOGICAL ENVIRONMENT QUALITY IN SHANXI PROVINCE BASED ON REMOTE SENSING

Abstract. Long term coal mining produces pollutants such as coal gangue, coal mine gas and mine water. With the rapid urbanization, the increased environmental burden has led to the deterioration of environmental pollution problems, which seriously restricts the harmonious and sustainable development of the ecological economy. In order to understand the changes of the ecological environment in Shanxi Province in the past seven years, this paper selects the ground remote sensing data of Shanxi Province in the winter of 2013–2019 to obtain remote sensing ecological indicators (RSEI) that comprehensively reflect the ground ecological status, and uses spatial autocorrelation and geological detectors to explore the driving factors of the ecological environment differences in Shanxi Province, revealing the dynamic mechanism of the RSEI differences in Shanxi Province. The results show that the overall ecological environment quality in winter in Shanxi Province has a downward trend from 2013 to 2017 and an upward trend from 2018 to 2019. The spatial distribution of ecological environment quality between 2013 and 2019 is positively correlated. The clustering and outlier analysis chart of RSEI shows that in the seven years from 2013 to 2019, there are stable high value clusters in the north of Shanxi Province, while there are more low value clusters in the south. The significance test results show that the output value of the primary industry and the output value of the secondary industry dominated from 2013 to 2019.

Identification of mixing water source and response mechanism of radium and radon under mining in limestone of coal seam floor

With the gradual increase of the coal mining depth, the mixing of multiple water sources intensifies and the activity of radium and radon in groundwater increases. Identifying the source of mine water inrush by using radium and radon isotopes is a new choice. In this paper, the mathematical statistics method, radioactive isotope decay theory, the mass conservation principle, and the numerical simulation method are used to analyze the influence of total dissolved solids (TDS), pH, and the hydrochemical ion content in groundwater on the isotope activity of radium, radon, uranium, thorium, and lead. The activity of thorium and lead is lower than the detection limit of the instrument, and the influence of coal mining activities on it is small. The simulation of the radium–radon mass balance in groundwater shows that the greater the adsorption coefficient (k) of solid particles in groundwater is, the more obvious the adsorption effect and the greater the influence on the radium–radon activity balance are. The radium–radon dating method is used to calculate the groundwater age. Results show that the groundwater age in the closed pit coal mining area is generally older than that in the mining coal mining area. Combined with the 222Rn, 226Ra, and 234U radioactive isotopes and temperature, a mixing water source identification model of limestone in the coal seam floor is constructed. The model shows that the radium activity and temperature of the groundwater are inversely proportional to the mixing ratio of the Permian sandstone water. From the closed pit coal mining area to the mining coal mining area, the radium radon activity of the groundwater increases gradually, the groundwater age decreases significantly, the water cycle is accelerated, the mixing ratio of the Permian sandstone water decreases gradually, the mixing ratio of the Ordovician limestone water increases gradually, and the risk of coal mine water inrush increases. The research results prove the feasibility of the new method for accurately discriminating the mixing water sources in coal mine areas, which is of great significance to the improvement of the theory of coal mine water disaster prevention and control.

Spatial Distribution Characteristics of Coal Mine Drainage Water Quality in China

Coal mine drainage (CMD) reuse is an important method for optimizing water resource supply in arid/semi-arid regions. This study analyzed the spatial distribution of water quality, management, and utilization strategies for CMD in China. In northwest, northeast, and north China, CMD was characterized by high levels of suspended solids, high salinity, neutral/weakly alkaline pH, and low levels of Fe/Mn. Based on existing water treatment processes, mine water reuse is safe and can support local water supply in these areas. In southern China, especially the southwestern regions, the CMD was characterized by low pH, high salinity, and high levels of Fe/Mn. These areas face high costs associated with mine water reuse and ecological and environmental risks. Therefore, the prevention and control of water pollution should be the focus of mine water management in these areas. To maximize the utilization of CMD, improving the norms and standards for mine water utilization is necessary, policy support for CMD reuse should be fortified, and a complete chain of coal mine water utilization should be developed. This study provides a reference for implementing water environmental protection strategies and mine water reuse policies.

Underground transient electromagnetic real-time imaging system for coal mine water disasters

Due to advantageous sensitivity to low resistance and noncomplicated operation, transient electromagnetic methods are the most widely used geophysical methods for advanced detection of coal-mining-disaster water bodies. To realize real-time imaging, we developed a wireless antenna attitude angle measuring instrument based on an electronic compass, which measures antenna attitude angle real-time. According to attitude angle information sent through WiFi to the host of transient electromagnetic real-time imager instruments, current transmission, signal acquisition, and antenna rotation angle information are achieved for real-time imaging. We studied the direct algorithm of the apparent resistivity of the whole-space transient electromagnetic field in overlapping loop mode based on double-logarithmic-transform piecewise least-squares fitting, which not only ensures accuracy but also accelerates calculation. On-site detection was carried out in a coal mine, and the detection results are generally consistent with the drilling results.

Dissolution of harmful trace elements from coal and the environmental risk to mine water utilization.

Under the pressure of water shortages, coal mine water has been allocated as a national water resource in China. However, the existence of harmful trace elements (HTEs) in coal mine water causes environmental risks and health concerns over its reuse. Through a lixiviation experiment, the dominant factors affecting the dissolution of HTEs in coal were simulated and analyzed, and the environmental risks of HTEs in coal mine water in China were evaluated for the first time. The average dissolved content levels of HTEs from coal were Mn > Cu > Zn > Ni > Ba > Cr > Co > V > Mo > Se > U > Pb > Cd, and the average maximum dissolution rates were Ni > Co > Mo > Zn > Cu > Cd > Mn > Se > Ba > Cr > U > Pb > V. Oxidation-reduction potential (Eh) and pH are the dominant factors controlling HTE dissolution. Higher oxygen exposure levels induce Eh and pH development, resulting in more HTE dissolution. This study constructed the dissolution potential index (FC) of HTEs from coal. Based on the results of the FC model, the areas with the highest migration potential and environmental risk of HTEs from coal seams to mine water are located in southern China, especially in the southwest, followed by areas of eastern Inner Mongolia and Shanxi and Shaanxi provinces. The corresponding risks in other regions are relatively low; thus, mine water utilization remains an effective option. This study provides an effective reference for the analysis of HTE enrichment in coal mine water and an evaluation of its safe utilization.

Coal Mine Water Level Detection and Reusability

Coal Mine Water Level Detection and Reusability