Coal Mine Research Articles

Effect of service quality and coal price perceptions on customer satisfaction at PT Bukit Asam, TBK

This study aims to analyse the effect of service quality and price perception on customer satisfaction of PT Bukit Asam Tbk. As one of the largest coal mining companies in Indonesia, customer satisfaction is a critical aspect to maintain market share in the midst of intense competition. The research was conducted using quantitative methods using questionnaires to customers in several operational units. The sample used in this study was 100 respondents with purposive sampling method. The results of multiple linear regression analysis show that service quality and perceived coal prices have a positive and significant effect on customer satisfaction. These findings indicate the importance of improving services and adjusting prices in accordance with customer expectations to maximise customer satisfaction and loyalty.

Research PIV-based model on subsidence caused by coal mining

The subsidence caused by coal mining could cause the destruction of roads and houses, and even the failure of infrastructures. Understanding of the mechanism of coal mining subsidence may provide early protecting to infrastructures on coming failure, but dynamic analysis of subsidence due to coal mining is currently needed. In this study we apply particle image velocimetry (PIV) method to reveal strata movement and subsidence according to the prototype and indoor physical model similarity experiment of Henan. Our result shows magnitude of the subsidence of overlying strata during the coal mining at different excavation thickness, that more coal mining thickness may produce more subsidence, and that shallower coal may cause more significant subsidence. Our result suggests that further PIV test combined with field monitoring data may be an effective measure to study subsidence mechanism and pattern helping to predict disaster caused by subsidence.

Recycling Gold Mine Tailings into Eco-Friendly Backfill Material for a Coal Mine Goaf: Performance Insights, Hydration mechanism, and Engineering Applications

Recycling gold mine overflow tailings for coal mine filling is crucial for sustainable mining. In this work, an eco-friendly, performance-controllable overflow tailings-fly ash-based backfill material is developed for coal mine filling. The effects of three critical factors, namely, the slurry concentration (SC), cement-sand ratio (C:S), and tailings-fly ash ratio (T:F), on the workability and uniaxial compressive strength (UCS) properties of the novel backfill material are thoroughly investigated, and an optimization of the corresponding formulation is conducted. The optimal formula for the backfill is determined to be a CS of 60%, a C:S of 0.10, and a T:F of 6:6. The hydration mechanism of the chosen typical mixtures is analyzed via X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy, and the results show that a needle-like Aft gel, identified as the major gelatinous product, is intricately intertwined to create an intricate network structure. As the T:F increases, the content of calcium and silicon oxide initially decreases but then increases, and the optimal mixture reaches a minimum value of 63.66%. The optimum specimen exhibits a peak wavenumber at 1,109.46cm-1 involving a Si-O stretching vibration bond. A comprehensive filling program at the Liangjia Coal Mine is successfully implemented. Approximately 0.27 tons of overflow tailings are utilized for every ton of backfills. The underground core-pulling backfill achieves a peak uniaxial compressive strength (UCS) of 7.56MPa after 28 d, surpassing design requirements and showing promise for coal mine filling applications. This study is expected to achieve the transformation of a coal mine goaf into a gold mine tailings pond.

Study on the separation efficiency of sheath flow respirable dust virtual impact separator under the influence of multiple parameters

To improve the separation efficiency of respirable dust separator in coal mine, a sheath flow virtual impact separator was designed. Through numerical simulation, the separation law of respirable dust in separator under the effect of various structural parameters, such as the spacing between nozzle and large-particle collection chamber (S), the width of the large-particle collection chamber (D), and sheath flow angle (θ), was obtained. The maximum difference between the results of experiment and simulation is only 4.72 %. The results show that the separation efficiency of separator at each particle size point increases continuously with the increase of S. When D increases, the deviation degree of the separation efficiency curve from the BMRC curve decreases and then increases. When θ increases, the overall change of separation efficiency curve is small. The parameter optimization scheme was obtained using response surface methodology. The research results provide reference for improving the structure of respirable dust separator in coal mine, and further promote the development of accurate monitoring technology for respirable dust.

Study on the mechanism and prevention system of creep induced instability of isolated coal pillars considering time effect

In response to the frequent occurrence of impact events in isolated coal pillars between the upper (lower) mountain areas of mining areas under conditions without obvious mining disturbance, this study takes multiple isolated coal pillar impact events that occurred in Zhaolou Coal Mine and Gengcun Coal Mine as examples. It conducts a mechanism study on the creep-induced impact ground pressure of isolated coal pillars considering the time effect. The occurrence of such impact ground pressure accidents often exhibits significant “lag” and “spontaneity”. Due to the unclear mechanism of occurrence and the difficulty in grasping the unloading timing, this type of impact ground pressure has become a typical hidden disaster, posing a serious threat to the deep mining of coal mines. Based on the analysis of the creep mechanical properties of coal and rock mass, the uniaxial compression acoustic emission creep test of coal body, and the FLAC3D numerical simulation, a creep instability impact mechanical model of coal and rock mass is established. This model reveals the mechanism of creep instability impact and the stress evolution law of coal and rock mass during creep. The mechanical and energy criteria for the occurrence of impact ground pressure in isolated coal pillars under the action of unstable creep are proposed. The study shows that the action of high ground stress is a necessary condition for the occurrence of "lag-type" impact ground pressure in isolated coal pillars. Long-term unstable creep will weaken the support strength of the entry. When the elastic energy accumulated in the isolated coal pillar exceeds its ultimate bearing capacity, impact instability will occur. Based on the mechanism of occurrence of such impact accidents, targeted deep hole blasting unloading measures are proposed, providing a good reference value for the prevention and control of "lag-type" impact ground pressure accidents in isolated coal pillars.

Recent Patents on Particle Wettability Measurement and Improvement

Background: As the coal mining industry becomes more mechanized, it leads to a large number of coal dust particles suspended in the air, polluting the surrounding environment, accompanied by an increase in fine-grained low-rank coal particles and a low recovery rate of a large amount of organic matter in the particles, wasting resources. Objective: The study of particle wettability can have an impact on spray dust reduction and particle flotation efficiency. By adjusting the hydrophilicity of coal powder particles, the generation of suspended coal dust can be effectively suppressed. By adding surfactants, the flotation separation efficiency of coal particles can be improved. Method: This article introduces the measurement method of particle wetting properties and methods to improve the wetting properties of particles, providing a reference for studying the wetting properties of particles Results: The measurement of particle wetting properties is more accurate, simple, and convenient. Improving the wetting properties of particles by adding additives has significant implications for later dust reduction and particle flotation. Conclusion: This thesis provides an important basis for studying the wettability of particles, modifying the wettability and hydrophilicity of particles, providing specific guidance for improving the wettability of particles for spray dust reduction and particle flotation, and greatly improving industrial production efficiency.

Predictors of employee well-being: A global measurements using reflective-formative model

BackgroundEmployee well-being (EW) is an integral part of occupational safety & health. Therefore, measuring EW is very important for holistically evaluating well-being instruments and measurement models. This research aimed to identify and confirm dimensions that significantly contribute to EW and also to examine the reliability and validity of the formative model of EW. MethodsThe survey consisted of 89 items from a well-being questionnaire administered to 426 employees in the coal mining industry, covering five domains. Measurements were analyzed using partial least squares–structural equation modelling (PLS-SEM) with SmartPLS 4.1.1. The measurement and analysis were conducted in two stages, the first of which used a reflective model. Subsequently, the results of the first stage were used in the second stage as a formative model to measure EW globally. Result and conclusionHome, Community, and Society (HCS), Health Status (HS), Workplace Environment and Experience (WEE), Workplace Policies and Culture (WPC), as well as Workplace Environment and Safety Climate (WPE) domain significantly contributed to EW, as identified through first-order reflective and second-order formative models. ContributionThis research developed a measurement model for EW with two orders: first-order reflective and second-order formative. It also offered practical insights for organizations and companies to measure and understand EW, providing a basis for implementing effective interventions.

Acoustic emission and electromagnetic radiation of coal-rock effective and interference signal identification utilizing generative adversarial learning and image feature mining

Acoustic Emission (AE) and Electromagnetic Radiation (EMR) are playing an increasingly important role in the field of coal and rock dynamic disaster early warning due to their accurate response to the evolution process. However, blasting, drilling, and other coal mine technical activities are easily to produce interference signals, which seriously affect the credibility of early warning information. Moreover, unbalanced samples and complex characteristic characterization cannot achieve accurate identification. This paper presents a novel identification method for effective and interference signal of AE and EMR based on generative adversarial learning and image feature mining. First, Kalman filter is applied to AE and EMR monitoring signals to remove noise and retain key features. The Wasserstein Generative Adversarial Network, then, resolves the imbalance between the sample numbers of effective and various types of interference signals to ensure generalization of the identification. The effective and interference signal samples are further converted graphically by Symmetrized Dot Pattern, and intuitive different distribution characteristics are obtained. Finally, the EfficientNet model accurately identified typical effective and six interference signals collected downhole. The practical case of a coal mine in Liaoning Province shows that the proposed method is feasible and effective, and can provide a basis for reliable early warning of coal and rock dynamic disasters.

Evolution characteristics of mining-induced fractures in overburden strata under close-multi coal seams mining based on optical fiber monitoring

Large-scale mining fractures resulting from repeated mining are a major cause of surface water loss in the northern Shaanxi mining area, China. Accurately detecting the evolution of mining-induced fractures is crucial for addressing the fragile ecological environment and ensuring coalmine production safety in this area. This study focuses on the close-multi coal seams mining at the Ningtiaota coalmine, northern Shaanxi, China, investigating the failure types of overburden rock, the evolution of mining-induced fractures, and the height of fracture zones. The results indicate that the failure type of overburden strata transforms from a “trapezoid shape” to an “overlapping trapezoid shape”, with the fracture zone height extending from 64.5 m to 158.5 m due to the superposition of secondary mining. Furthermore, the evolution characteristics of mining-induced fractures shift from a “three-stage and three-step” model to a “three-stage and two-step” model. A characterization model of overburden deformation based on optical fiber sensing is proposed to effectively describe the strain distribution characteristics of overburden failure. This model reveals the spatiotemporal evolution of overburden deformation from the perspective of “horizontal three areas and vertical three zones”, enabling real-time characterization of overburden deformation. The results demonstrate a relative error of less than 5.0 % between optical fiber monitoring and other methods, excluding theoretical calculations. This study offers a technical solution for detecting mining-induced fractures in the northern Shaanxi mining area and holds significant implications for broader studies of overburden deformation and failure under repeated mining.

Analysis of the Impacts of Coal Mining on Baseflow Changes Under the Budyko Framework: A Case Study of Northern Shaanxi, China

Coal mining alters the regional and local hydrogeological conditions and subsurface parameters, significantly impacting the hydrological cycle. Baseflow is particularly sensitive to changes in subsurface parameters and hydrogeological conditions. Therefore, studying the impact of coal mining on baseflow is crucial for understanding its effects on the water cycle. In this paper, 9 segmentation methods are used to separate the baseflow, after the applicability analysis, the Chapman-Maxwell and Boughton-Chapman separation methods were used. The Mann-Kendall and Pettitt tests are employed to determine the mutation years of baseflow. Finally, within the Budyko framework, the elasticity coefficient is calculated to estimate the changes in baseflow attributed to variations in precipitation, potential evapotranspiration, and underlying surface index. The results indicate that: (1) Based on the comparison of results and error analysis, we conclude that the Chapman-Maxwell separation method and the Boughton-Chapman separation method are the most suitable for the typical basins in the Shaanxi mining area. (2) During the study period, baseflow experienced a mutation in the late 1990s and showed an overall declining trend. (3) There is spatial heterogeneity in the influence of coal mining activities on baseflow, which has a negative impact. The change of base flow after mutation is -2.86×108 m3.

Effects of functional microbial agents on the microbial community and fertility of reclaimed soil in a coal mining area

Low soil fertility is the main factor limiting ecological restoration in coal mining reclamation areas. To improve the nutrient status and microbial community structure of reclaimed soil in coal mining areas, we tested a management strategy combining functional microbial agents, NPK, organic fertilizer, and straw to amend reclaimed soil. We selected corn as the crop for our greenhouse pot experiment, with a cultivation period of 80 days. Greenhouse pot trials were conducted with six treatments: no microbial agent (NMA), including CK (NPK), M (organic fertilizer and NPK), and S (straw and NPK); microbial agent (MA), including B (microbial and NPK), BM (microbial agent, organic fertilizer and NPK fertilizer), and BS (microbial agent, straw and NPK fertilizer). The results showed that the adding microbial agents changed the community structure of bacteria and fungi, and significantly changed the indicator microbial composition. The MA treatment group had an increase in five bacterial microbial network modules related to C and N functionalities such as Proteobacteria and Nitrospirae. In comparison to the B treatment, the combination of microbial agents with organic materials (BM and BS) significantly enhanced soil nutrient contents, including soil organic carbon (SOC), total nitrogen (TN). Therefore, the addition of functional microbial agents (Sphingomonas leidyi, Paenibacillus amylolyticus, and Paenibacillus mucilaginosus), especially in combination with organic materials, can significantly improve the contents of carbon, nitrogen and phosphorus nutrients, bacterial functional activity, and beneficial bacterial abundance in reclaimed soil, which is essential for the rapid improvement of reclaimed soil fertility in coal mining areas.

Metagenomic Insights into Coal Slag Remediation Effects on Soil and Microbial Health in Qinghai’s Muli Coal Mine

Long-term coal mining in the Muli coal mine area of Qinghai Province has degraded soil quality and reduced microbial diversity, making it imperative to implement effective ecological restoration measures to restore soil quality and enhance ecosystem functions. This study evaluated soil samples under 11 ecological restoration treatments using metagenomic sequencing combined with soil quality analysis to explore the responses of the microbial community structure and function to identify effective restoration measures. This study demonstrated that ecological restoration significantly increased the soil microbial diversity and richness, with the MLII1 (soil samples treated with a chemical weathering agent, attapulgite, and a microbial agent) and MLIII1 (soil samples treated with sheep manure (2.4 kg/m2), granular organic fertilizer (1.2 kg/m2), and the microbial agent) treatment groups performing exceptionally well. Further analysis of the functional networks revealed that although the MLII2 (soil samples treated with the chemical weathering agent and attapulgite) treatment group did not exhibit the highest species diversity, it exhibited the highest functional network complexity. The results of hierarchical clustering analysis showed that the microbial community of the MLII2 treatment group was most similar to that of the natural meadows compared to the other treatment groups. From the perspective of overall ecological restoration, this study concluded that the MLII2 treatment group exhibited the most favorable ecological restoration outcomes. This finding emphasizes the importance of not only enhancing microbial diversity but also prioritizing the restoration of community functions, especially for the recovery of fragile high-altitude ecosystems.

Using geochemical and geophysical data to characterise inter-aquifer connectivity and impacts on shallow aquifers and groundwater dependent ecosystems.

Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia’s Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable 3H (0.43 TU), and activities of radiocarbon a14C (14.1 – 95.3 pMC) and chlorine-36 R36Cl (78.1 x10-15 – 161 x10-15) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO3 and F concentrations and heavy fraction hydrocarbons (>100 μg/L C10 - C40) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine’s groundwater impacts, which was the basis of the mine’s approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.

Mesoscale modeling on the influence of surfactants on seepage law during water injection in coal

To investigate the mesoscopic influence of surfactants on seepage law during water injection in coal seam, this paper innovatively establishes a fluid transport lattice Boltzmann (LBM) model by incorporating the seepage resistance generated from the porous media and external forces, which embodies the impact of wettability degree resulted from cocamidopropyl betaine (CAB), sodium dodecyl sulfate (SDS), and coconutt diethanol amide (CDEA) reagents at a 0.1% concentration. The main conclusions derived from this investigation are as follows: Firstly, as the lattice number in the X direction increases, the average seepage velocities in coal samples treated by deionized water, 0.1% CAB, 0.1% SDS, and 0.1% CDEA reagents (Nos. 1, 2, 3, and 4) exhibit three distinct stages: rapid decline, slow decline, and steady decline; in comparison to raw coal sample, modified coal samples demonstrate decreases of 20.84%, 33.91%, and 61.70%, respectively. Secondly, the critical values of displacement pressure difference exist during the phenomenon that modified reagents spread out in the entire flow channel, which are 3.5 MPa, 3.5 MPa, and 5.2 MPa, respectively, for coal samples Nos. 2, 3, and 4; this signifies that surpassing these critical values help prevent issues such as blank belts within the wetting range and insufficient dust control. Finally, at a displacement pressure difference of 0.01 (lattice unit), the average velocity ratios for samples (Nos. 2, 3, and 4) are 0.78, 0.56, and 0.37(lattice unit), respectively; notably, the water flow velocities in modified coal samples are lower compared to that in raw coal sample, indicating that the addition of surfactants impede the seepage process of water injection in coal seam. Moreover, when the displacement pressure difference reaches 0.03 (lattice unit), the velocity ratio of CDEA-modified coal sample exceeds 100%; this means that when the displacement pressure difference surpasses 15.6 MPa, the water injection effect of CDEA-modified coal sample begins to be improved. These research findings offer a theoretical basis for enhancing water injection technology in coal mines.

Preparation and characterization of a low viscosity spray dust suppressant based on xanthan gum grafted sodium α-olefin sulfonate copolymer with proactive coal-adhesive and surface-active properties

To address the problem of the high viscosity of current composite dust suppressants, which results in spray droplet sizes that are not optimal for capturing respirable dust, a low viscosity, proactive coal-adhesive, long-lasting spray dust suppressant, XG-AOS/Tre, has been developed. The suppressant utilizes xanthan gum (XG) from microbial fermentation, with α-olefin sulfonate grafted onto its hydroxyl groups to form a copolymer (XG-AOS), reducing its viscosity while maintaining the surface activity of the hydrocarbon chain and its affinity for coal dust. It has a weighted average molecular weight of 398341, a surface tension of 26.1 mN/m, a viscosity of 1.59 mPa·s, and a contact angle of 48° with coal cake. The suppressant achieves a total dust suppression rate of 85.7 % and a respirable dust suppression rate of 85.9 %. Because of its surface activity and high molecular weight, it efficiently wets and settles coal dust. It retains 47.3 % of the water in its solution 24 h after being sprayed and forms an adhesive film upon complete evaporation, providing the coal dust with resistance to wind erosion. The dust suppressant improves the dust suppression rate for dust control in coal mining. Its properties contribute to the sustainable development and environmental protection of the coal industry.

Study on the thermal hazards of anionic surfactant AES on lignite via experiments and calculations

Spray dust reduction is a commonly used dust reduction method in coal mines and has been widely adopted. However, the thermal stability of coal dust after being wetted by dust suppressants remains unknown. The work aimed to investigate the potential environmental hazards posed by the secondary dust dispersion resulting from the cracking of lump coal dust after being wetted by surfactants and subsequently air-dried. Lignite and AES were used as experimental samples. Use thermodynamic equations to analyze, calculate, and compare the changes in the average apparent activation energy of lignite before and after AES solution wetting. Compared with lignite before AES solution wetting, the combustion characteristic index of lignite decreased by 1.93 % after wetting, and before and after AES solution wetting, the average apparent activation energy of lignite calculated by reaction kinetics methods decreased by 7.6 %, 6.7 %, and 17.1 % respectively. FTIR analysis shows the proportion of aliphatic hydrocarbons in lignite after AES solution wetting has decreased compared with before wetting, and the proportion of oxygen-containing functional groups has shown an upward trend. The work elucidated the complex microscopic mechanisms underlying hazards caused by secondary dust dispersion, providing new scientific evidence for preventing and controlling coal dust explosion accidents.

Characteristics of rock strength failure and identification of hazardous areas in the roof of deep mining stope

The roof of deep mining stopes is notoriously unstable and challenging to manage due to high in-situ stress and deteriorating rock conditions. To address this issue, a comprehensive approach was employed, incorporating indoor physical experiments, numerical simulations, and field tests to investigate the stope roof rock composition characteristics and strength failure modes in the Laoyingshan deep coal mine. The study revealed the distribution characteristics of the high in-situ stress field in this mining area and delineated different levels of hazards in the roof. The results indicate that, under identical lithological conditions, the mineral composition of deep rock formations is complex. Changes in some mineral components and properties were observed, leading to increased expansiveness and water absorption in clay minerals such as sodium montmorillonite and kaolinite within the basic roof layer. In simulated tests of surrounding rock strength in deep mining stopes, as stress levels approached 2 MPa, the damage factor increased, showing a trend of localized concentration. Internal damage began to exhibit noticeable spatial evolutionary expansion patterns and gradual nucleation. When stress exceeded 8 MPa, rocks transitioned from macroscopic fracture surfaces to microscopic fragmentation zones, with a sudden decrease in stiffness degradation values, internal instantaneous collapse, and phenomena akin to “rock burst” under high stress disturbance. In-situ stress testing determined that the stress field in the deep mining zone of Laoyingshan is in a thrust fault stress state, with horizontal stress predominance. The maximum stress direction is predominantly southwest-northeast, with stress magnitude reaching 25.49 MPa. By arranging post-mining and pre-mining borehole observation stations and utilizing image grayscale fracture recognition technology in MATLAB, the roof was classified into four danger levels: “extremely broken,” “broken,” “significant fractures,” and “minor fractures.” Main control measures for coupling grouting in deep-shallow zonation rigidity were proposed based on these classifications.

A sensing system and solving method for dynamic detection of relative pose of hydraulic support group

The precise detection of the pose of hydraulic support groups is crucial for the construction of intelligent coal mines. Addressing current challenges in comprehensive position sensing of support groups, such as one-sided descriptions, missing information, and limited detection capabilities, this paper, based on the concept of digital twin, proposes a sensing system and solving method for dynamic detection of the relative pose of hydraulic support group. Initially, a relative pose detection model, based on the six-point localization principle, is proposed by combining existing sensor information. Then, a sensing system is designed, incorporating a photoelectric detection device for monitoring key position parameters and virtual sensors for determining pose information. Consequently, a method for dynamically deriving relative positions, driven by the fusion of real-virtual iterative solving, real-virtual error feedback, and iterative condition optimization, is established. Finally, a relative pose dynamic detection system for a hydraulic support prototype is constructed in a laboratory environment. Experimental results demonstrate that the sensor system and the relative position detection method designed in this paper achieve a relative position accuracy of over 95.32 % for the hydraulic support, with a dynamic reconstruction time of less than 0.2 s. This verifies the rationality of the sensor system and the feasibility and accuracy of the dynamic deduction method. To sum up, this work provides a theoretical foundation and technical support for the autonomous perception of hydraulic support group, autonomous frame adjustment between frames, and overall straightness adjustment. It also lays the groundwork for further research and the advancement of information-physical systems in the fully-mechanized mining face.

Terrestrial gamma radiation dose (TGRD) rates and radiological risk assessments in Tiru region of the Naga Schuppen Belt, India

The aim of the present study is to assess the levels of dose rates and the potential risks of exposure to terrestrial gamma radiations in indoors and outdoors in houses in Tiru coal mining area. A highly sensitive portable micro-R gamma survey metre incorporated with a NaI (Tl) scintillator has been used for this study. Indoor and outdoor gamma dose rates (GDRs) have been estimated to be 58.5-178.3 nGy h-1 and 55.5-81.9 nGy h-1, respectively, with averages of 89.7 7.4 nGy h-1 and 65.7 5.8 nGy h-1, considerably higher than the reported global population-weighted averages. The annual effective doses (AEDs) for indoors and outdoors have been estimated to be in the ranges of 0.29-0.87 mSv y-1 and 0.07-0.1 mSv y-1, with averages of 0.44 0.04 mSv y-1 and 0.08 0.01 mSv y-1, which are marginally higher than the reported global averages. The excess lifetime cancer risk (ELCR) has been calculated and found to be in the range of 1.2 10-3-3.4 10-3 with an average of 1.8 10-3. This study contributes significantly to the scientific understanding of radiation exposure in an open-cast coal mining area as well as its potential impact on human health.

Groundwater for Sustainable Development Characteristics of Iron-Sulfur Metabolism and Acid-Producing Microorganisms in Groundwater Contaminated by Acid Mine Drainage in Closed Coal Mines

Groundwater for Sustainable Development Characteristics of Iron-Sulfur Metabolism and Acid-Producing Microorganisms in Groundwater Contaminated by Acid Mine Drainage in Closed Coal Mines