Search Results (131)

In the process of the work of a coal power station is formed ash and slag, which, along with process water, are deposited in the dumps. Coal ash waste dumps significantly degrade the surrounding environment due to their unprotected surfaces, which are highly susceptible to wind and water erosion. This results in the dispersion of contaminants into adjacent ecosystems. Pollutants migrate into terrestrial and aquatic systems, compromising soil quality and water resources, and posing documented risks to the environment and human health. Primary succession on the coal ash dumps of the Apatity thermal power plant (Murmansk Region, NW Russia) was initiated by cyanobacterial colonization. We studied cyanobacterial communities inhabiting three spoil sites that varied in time since decommissioning. These sites are characterized by exceptionally high concentrations of calcium and magnesium oxides—levels approximately double those found in the region’s natural soils. A total of 18 cyanobacterial taxa were identified in disposal sites. Morphological analysis of visible surface crusts revealed 16 distinct species. Furthermore, 24 cyanobacterial strains representing 11 species were successfully isolated into unialgal culture and tested with a molecular genetic approach to confirm their identification from 16S rRNA. Three species were determined with molecular evidence. Cyanobacterial colonization of coal fly ash disposal sites begins immediately after deposition. Primary communities initially exhibit low species diversity (four taxa) and do not form a continuous ground cover in the early years. However, as succession progresses—illustrated by observations from a 30-year-old deposit—spontaneous surface revegetation occurs, accompanied by a marked increase in cyanobacterial diversity, reaching 12 species. Full article

Assessing the risks associated with waste disposal is essential for environmental protection and sustainable development, especially given concerns about the impact of industrial activities on the environment. This study analyses soil contamination in the Defor Petrila tailings-dump area caused by the deposition of waste material resulting from coal exploitation. To characterise the heavy-metal contamination in detail, we applied a comprehensive methodology that includes the calculation of the geo-accumulation index (I_geo), contamination factor (Cf), and potential ecological risk index (PERI), along with an analysis of the heavy-metal concentration isolines and a statistical analysis using the Pearson correlation coefficient. The results reveal varying levels of heavy-metal concentrations, as indicated by the calculated indices. The findings underscore the need for remediation and ongoing monitoring to mitigate the environmental impacts. This study provides a scientific basis for decision making in environmental management and highlights the importance of assessing mining-waste disposal near human settlements using various contamination-assessment methods. Full article

Anthropogenic revegetation allows effective and timely soil development in mine restoration areas. The evaluation of soil quality is one of the most important criteria for measuring reclamation effectiveness, providing scientific reference for the subsequent management of ecological restoration projects. The aim of this research was to further investigate the influence of revegetation on mine-reclaimed soils in a semi-arid region. Thus, a coal-gangue dump within the afforestation chronosequence of 1 and 19 years in Shanxi Province, China, was selected as the study area. We assessed the physicochemical properties and nutrient stock of topsoils under four revegetation species, i.e., Pinus tabuliformis (PT), Medicago sativa (MS), Styphnolobium japonicum (SJ), and Robinia pseudoacacia ‘Idaho’ (RP). A two-way ANOVA revealed that reclamation age significantly affected SOC, TN, EC, moisture, and BD (p < 0.05), while the interaction effects of revegetation type and age were also significant for TN and moisture. In addition, SOC and TN stocks at 0–30 cm topsoil at the RP site performed the best among 19-year reclaimed sites, with an accumulation of 62.09 t ha⁻¹ and 4.23 t ha⁻¹, respectively. After one year of restoration, the MS site showed the highest level of SOC and TN accumulation, which increased by 186.8% and 88.5%, respectively, compared to bare soil in the 0–30 cm interval, but exhibited declining stocks during the 19-year restoration, possibly due to species invasion and water stress. In addition, an integrated soil quality index (ISQI) and the partial least squares structural equation model (PLS-SEM) were used to estimate comprehensive soil quality along with the interrelationship among influencing factors. The reclaimed sites with an ISQI value > 0 were 19-RP (3.906) and 19-SJ (0.165). In conclusion, the restoration effect of the PR site after 19 years of remediation was the most pronounced, with soil quality approaching that of the undisturbed site, especially in terms of soil carbon and nitrogen accumulation. These findings clearly revealed the soil dynamics after afforestation, further providing a scientific basis for choosing mining reclamation species in the semi-arid regions. Full article

Mining waste from both underground and open-pit mines is typically placed in surface sites known as mine waste dumps. Over time, as large volumes of mining waste accumulate, these dumps become higher due to the limited surface area allocated to dumping. Ensuring the stability of mine waste dumps is a major concern for both mining operations and local governments due to safety risks to the dumps themselves and their surrounding environments. In some cases of mine waste dump, spontaneous combustion poses a significant challenge, affecting not only the environment but also the slope stability of mine waste dumps. This review synthesizes existing research on the mechanisms of spontaneous combustion, its thermal effects, and the implications for geomechanical stability in mine waste dumps. It also examines methods for monitoring and controlling these processes, identifies gaps in the current research, and suggests directions for future studies. The review also reveals that combustion-induced temperature changes, material degradation, and gas generation significantly impact the geotechnical properties of building material dumps, contributing to slope failure. This review is expected to provide valuable insights that help mining authorities assess risks, minimize impacts, and implement preventive measures to mitigate unexpected spontaneous combustion-induced slope failures in mine waste dumps. Full article

Land reclamation is crucial for restoring ecosystems in mining areas, improving land use efficiency, and promoting sustainable regional development. Traditional single-indicator assessments fail to capture the full complexity of reclamation, highlighting the need for a more comprehensive evaluation approach. This study combines field-measured and remote sensing data to develop multiple evaluation indices, creating a comprehensive framework to assess reclamation effectiveness. A soil quality index based on the Minimum Data Set (SQI_MDS) was developed to analyze spatial variations in soil quality, efficiently capturing key soil attributes. Remote sensing data were used to calculate the Dump Reclamation Disturbance Index (DRDI) and the Enhanced Coal Dust Index (E_CDI) to evaluate vegetation recovery and ecological improvements. The Comprehensive Evaluation Quality Index (CEQI) was introduced, synthesizing soil, vegetation, and ecological conditions for a holistic assessment. Key findings include significant soil quality improvement over time, with MDS effectively capturing variations; vegetation recovery increased with reclamation duration, though regional disparities were observed; ecological conditions steadily improved, as evidenced by a decline in ECDI values and reduced contamination; and the CEQI reflected overall improvements in reclamation effectiveness. This study offers a practical framework for coal mining land reclamation, providing scientific support for decision-making and guiding effective reclamation strategies for ecological restoration and sustainable land management. Full article

This study was conducted at a fixed monitoring site in the southern dump of the large-scale Antaibao open-pit coal mine of China Coal Pingshuo, using long-term monitoring methods. Based on data from 2019 and 2024 in the reclaimed area of the Pingshuo open-pit coal mine, all seedlings and saplings within the Robinia pseudoacacia L. + Ulmus pumila L. + Ailanthus altissima (Mill.) Swingle mixed forests were studied to analyze changes in their abundance and the driving factors influencing their survival rates from 2019 to 2024. The main conclusions are as follows: (1) The species composition of seedlings and saplings remained unchanged but the number of seedlings increased significantly. The majority of newly recruited seedlings were U. pumila., accounting for 92.22% of the total new seedlings, whereas R. pseudoacacia had the highest mortality rate among seedlings. The distribution patterns of seedling-to-sapling transition, sapling-to-tree transition, and seedling–sapling mortality were generally consistent with the overall distribution of seedlings and saplings at the community level. (2) At both the community and species levels, the optimal models for seedling and sapling survival were the height model and the biological factor model. Overall, survival rates of both seedlings and saplings showed a significant positive correlation with height. (3) The biological factors affecting the survival of U. pumila saplings were the basal area (BA) at breast height and the number of conspecific adult trees. The former was significantly negatively correlated with U. pumila seedling survival, while the latter was positively correlated. For R. pseudoacacia seedlings, the key biological factors were the number of heterospecific adult trees and the number of heterospecific seedlings. The former was significantly negatively correlated with survival, whereas the latter was significantly positively correlated. The primary factor influencing sapling survival was sapling height, which showed a significant positive correlation. Full article

Observing coal mining and reclamation activities using remote sensing avoids the need for physical site visits, which is important for environmental and land management. This study utilizes deep learning techniques with a U-Net and ResNet architecture to analyze Sentinel imagery in order to track changes in coal mining and reclamation over time in Tapin Regency, Kalimantan, Indonesia. After gathering Sentinel 1 and 2 satellite imagery of Kalimantan Island, manually label coal mining areas are used to train a deep learning model. These labelled areas included open cuts, tailings dams, waste rock dumps, and water ponds associated with coal mining. Applying the deep learning model to multitemporal Sentinel 1 and 2 imagery allowed us to track the annual changes in coal mining areas from 2016 to 2021, while identifying reclamation sites where former coal mines had been restored to non-coal-mining use. An accuracy assessment resulted in an overall accuracy of 97.4%, with a Kappa value of 0.91, through a confusion matrix analysis. The results indicate that the reclamation effort increased more than twice in 2020 compared with previous years’ reclamation. This phenomenon was mainly affected by the massive increase in coal mining areas by over 40% in 2019. The proposed method provides a practical solution for detecting and monitoring open-pit coal mines while leveraging freely available data for consistent long-term observation. The primary limitation of this approach lies in the use of medium-resolution satellite imagery, which may result in lower precision compared to direct field measurements; however, the ability to integrate historical data with consistent temporal coverage makes it a viable alternative for large-scale and long-term monitoring. Full article

During surface coal mining, vast amounts of overburden waste materials—called spoils—are excavated and dumped, forming massive heaps, the sustainable exploitation of which is a top priority globally. This study addresses the advanced geotechnical characterization of spoil materials, focusing on lignite mine spoil heaps, which are often ignored due to their highly heterogeneous nature. This research quantifies the spatial variability in spoil materials from a large heap in Greece, highlighting the importance of a robust geotechnical framework for their effective reclamation. Using statistical analysis and variogram modeling, the scale of fluctuation (SoF) was derived for both the vertical and horizontal directions. The SoF values for spoil properties are found to be on the high end of the natural soil range. Vertical correlations are observed for distances over 10 m, occasionally reaching 20 m, indicating significant spatial variability; in the horizontal direction, the SoF reaches up to 285 m. These findings suggest that spoil elements exhibit important spatial dependence, which is critical for their proper design and exploitation. The results provide a basis for future research and the use of advanced numerical tools, such as the random finite element method, to support geotechnical design and the sustainable exploitation of spoil heaps. Full article

Coal gangue dumps, a byproduct of coal mining, contribute significantly to heavy metal contamination, impacting soil and water quality. In order to assess the levels of heavy metal contamination in soils at different stages of abandonment, this study investigated the role of Miscanthus floridulus (M. floridulus) in the spatial distribution and remediation of six heavy metals (Cd, Cr, Mn, Ni, Cu, and Pb) in coal gangue dump soils abandoned for 0, 8, and 12 years in Pingxiang City, Jiangxi Province, China. Fieldwork was conducted at three sites operated by the Pingxiang Mining Group: Anyuan (active, barren), Gaokeng (8 years, natural vegetation), and Qingshan (12 years, partially remediated). Anyuan remains largely barren, while Gaokeng supports natural vegetation without formal remediation. In contrast, Qingshan supports diverse plant species, including M. floridulus, due to partial remediation. Using a randomized design, root exudates, heavy metal concentrations, and soil properties were analyzed. The results showed that Cd poses the highest ecological risk, with concentrations of 64.56 mg kg⁻¹ at the active site, 25.57 mg kg⁻¹ at the 8-year site, and 39.13 mg kg⁻¹ at the 12-year site. Cu and Pb showed accumulation, while Cr and Mn decreased over time. Root exudates from M. floridulus enhanced metal bioavailability, influencing Cd, Cr, and Ni concentrations. These findings highlight the importance of rhizosphere processes in metal mobility and inform sustainable remediation strategies for post-mining landscapes. Full article

Autogenously calcined clays from tailings dumps, which are formed by the ignition of the contained residual coal, represent a huge resource of potentially pozzolanic material worldwide. This work presents preliminary studies of samples from the Western coal regions in Germany and investigations on the first industrially produced cement with autogenously calcined tailings concerning its suitability as supplementary cementitious material (SCM). Samples of the tailings materials and blended cements were thoroughly characterized physically, chemically and mineralogically. The reactivity was studied using the R³ test and mortar compressive strength testing. The influence on cement hydration was studied using X-ray diffractometry (XRD) and isothermal calorimetry. The preliminary investigations showed that the material is basically suitable as SCM, as it consists mainly of SiO₂ and Al₂O₃, which partially occurs in X-ray amorphous form and has a low content of impurities, which can impair cement properties such as carbon or sulfur. The R³ reactivity and the relative compressive strength differed significantly depending on the sample. For the industrial cement production trial, low-processed material was used which still contained inert fractions. The average sample showed a relatively low R³ reactivity but still significantly higher than mostly inert materials such as limestone or quartz powder. Calorimetry and XRD investigations on cement pastes showed that the clinker reactions remain basically unaffected by the tailings. Mortar tests showed that the material contributes to strength development at a late age. It can be concluded that the tailings are basically suitable as SCM and, in appropriate blends, the clinker factor and, thus, the CO₂ footprint of cement can be reduced. Full article

Unmanned underground articulated dump trucks (UADTs) are an important direction for the coal mining industry to vigorously promote automation and intelligence. Among these, tracking and controlling the motion trajectory is the key weak link. This paper presents a kinematic analysis of the stationary turning process of UADTs. Then, a posture state model for articulated trucks is established. The objective is to optimize the control method and further improve trajectory tracking accuracy. Based on the advantages and disadvantages of the feedback linearization control (FLC) method, a sliding mode control method based on the Ackermann formula (ASMC) and integral type switch gain (ISMC) are proposed. Finally, hardware-in-the-loop simulation verifies the superiority and tracking quality of the controller. The results show that the ASMC controller can control the lateral position deviation, course angle deviation, and curvature deviation around 10 cm, 0.04 rad, and 0.08 m⁻¹ in the hardware-in-the-loop simulation environment. The ISMC controller can control the lateral position deviation, course angle deviation, and curvature deviation near 8 cm, 0.01 rad, and 0.02 m⁻¹, and can also effectively control the jitter problem. Each deviation is stabilized within 10 s. This provides a reference for the development of trajectory tracking strategies for articulated vehicles. Full article

Post-mining land in areas where mineral extraction has occurred may constitute a significant portion of the land used for various purposes. Such land serves as soil-forming parent material for developing anthropogenic soils, which sometimes exhibit unfavorable physicochemical properties. The toxicity of the waste generated during lignite mining is due to a number of factors, whose determination permits the identification of its origin for the subsequent design of technologies for the waste reclamation. The purpose of the study, in consistence with sustainable development, is to identify the causes of the toxicity of brown coal waste from the Lengerskoye deposit, in southern Kazakhstan. These studies have provided the results essential for planning remedial actions necessary to improve the well-being of the local population, in accordance with the principles of sustainable development. The studies were performed using single extraction; forms of Al, Fe, and Mn; soil texture; elemental analysis; phytocoenosis analysis; and diffractometric, IR spectroscopic, SEM, route reconnaissance, and comparative statistical methods. A decrease in the biodiversity of plant species was noted, with a gradual increase with distance from the waste storage sites. The most resistant plant species in the vicinity of the waste dump were Cynodon dactylon (L.) Pers and Alhagi pseudalhagi (M. Bieb.) Desv. ex B. Keller & Shap., while Dodartia orientalis (L.) was the only plant species found at the edge of the waste dump. The high toxicity of lignite waste is determined by such factors as low pH values, about 3.0; high content of active forms of aluminum, iron, and manganese (344.0, 0.90, and 20 mg/kg); high electrical conductivity—2835 µS/cm; waste composition poor in nutrients; and climate aridity. It has been observed that a content of exchangeable aluminum above 100 mg/kg resulted in an almost complete lack of vegetation. Full article

Large-scale coal mine dumps are formed during the mining process of coal resources. These coal mine dumps comprise impoverished soil, posing significant challenges for vegetation restoration. To address this problem, soil microbial (EM) agents and fly ash have effectively improved soil quality. However, the effects of different application ratios on the quality of sandy soil in coal mine dumps are still unclear. This study aims to explore the applicable ratio for sandy soil in coal mine dumps. This study employed a field-based potted experiment design. A two-factor complete factorial experimental setup was utilized, with four levels of EM microbial agent to sandy soil weight ratio (0 g/kg, 0.1 g/kg, 0.2 g/kg, and 0.3 g/kg) and four levels of fly ash to sandy soil weight ratio (0 g/kg, 25 g/kg, 50 g/kg, and 75 g/kg), and the mixing of EM microbial agents and fly ash with the sandy soil was carried out at different ratios. Subsequently, the study examined the impacts of various dosages on the physicochemical properties of soil within the mine spoil heap, and a soil quality index was derived to quantify these effects. The application of EM microbial and fly ash resulted in significant improvements in the physicochemical properties of the soil compared to the control group. Notably, the combined application of EM microbial agent and fly ash exhibited superior effects on soil physicochemical properties compared to the individual applications of EM microbial agent or fly ash. Specifically, when the EM microbial agent concentration was 0.2 g/kg and the fly ash content was 75 g/kg, the enhancement in soil quality was most pronounced, with a soil quality index of 0.78. Mantel analysis revealed that the growth index and photosynthetic index of Corethrodendron fruticosum were primarily driven by soil total nitrogen and organic carbon. The research results can provide guidance and technical support for soil improvement in mining areas. Full article

Soil degradation caused by mining activities has seriously affected the ecological environment of mining areas. Improving the soil quality is the key to solving this problem. This study examined the impact of adding Effective Microorganism (EM) agents and maize straw to the soil from the dump of the Ordos Rongheng open-pit coal mine. We conducted a two-factor complete experiment, varying the amounts of EM agents (0 g·kg⁻¹, 0.1 g·kg⁻¹, 0.2 g·kg⁻¹, 0.3 g·kg⁻¹, and 0.4 g·kg⁻¹) and maize straw (0 g·kg⁻¹, 5 g·kg⁻¹, 10 g·kg⁻¹, 15 g·kg⁻¹, and 20 g·kg⁻¹). Changes in the soil’s physical, chemical, and biological properties were assessed using a six-month-long potting experiment, and a minimum data set was established for soil quality evaluation. Our results indicated that both EM agents and maize straw improved the soil quality. Both additions reduced the soil’s bulk density and pH while increasing its porosity, organic matter, total available nutrients, enzyme activity, and microbial diversity. However, maize straw had no significant effect on the soil moisture content and total available phosphorus, and EM agents did not significantly impact organic matter. The interaction between the two treatments was not significant for soil moisture content, capillary porosity, and total potassium. Finally, we identified five key indicators affecting soil’s quality: the bulk density, available potassium, alkaline phosphatase, bacterial Chao1 index, and fungal Shannon index. The soil quality index (SQI) ranged from 0.158 to 0.568, with the highest SQI being observed with 0.1 g·kg⁻¹ EM agents and 20 g·kg⁻¹ maize straw, which was significantly higher than those from other treatments. New insights into the improvement of soil quality in open-pit mines are provided by these results, which may help guide future ecological restoration of mines. Full article

The increasing use of renewable energy sources, such as wind and solar energy, presents challenges to the stability and efficiency of other energy sources due to their intermittent and unpredictable surpluses. The unintended consequence of stabilizing the power supply system is an increase in emissions and external costs from the suboptimal use of coal power plants. The rising number of RES curtailments needs to be addressed by either the adjusting energy supply from fossil fuel or the flexible energy consumption. In Poland’s energy mix, coal-fired power plants are a critical component in ensuring energy security for the foreseeable future. Using domestic lignite to generate a total power of 8.5 GW can stabilize the national power supply, as it is currently done in Germany, where 15 GW of lignite-fueled power units provide the power supply base for the country. The leading Belchatów power plant comprises 10 retrofitted units and one new unit, with a total rating of 5.5 GW. Access to the new coal deposit, Zloczew, is necessary to ensure its longer operation. The other domestic lignite power plants are located in Central Poland at Patnów (0.47 GW from the new unit and 0.6 GW from its three retrofitted counterparts) and located in the Lusatian lignite basin at Turów (operating a brand new unit rated at 0.5 GW and retrofitted units with a total rating of 1.5 GW). The use of this fuel is currently being penalized as a result of increasing carbon costs. However, the continuous surface mining technology that is used in lignite mines is fully electrified, and large amounts of electric energy are required to remove and dump overburden and mining coal and its conveying to power units (the transport of coal from the new lignite mine Zloczew to the Belchatów power plant would be a long-distance operation). A possible solution to this problem is to focus on the lignite fuel supply operations of these power plants, with extensive simulations of the entire supply chain. A modern lignite mine is operated by one control room, and it can balance the dynamic consumption of surplus renewable energy sources (RESs) and reduce the need for reduction. When a lignite supply chain is operated this way, a high-capacity power bank can be created with energy storage in the form of an open brown coal seam. This would enable an almost emission-free supply of cheap and domestic fossil fuel, making it insensitive to changes in the world prices of energy resources for power units operating at the base of the system. Furthermore, extending the life of relatively new and efficient lignite-fired units in Poland would facilitate the decommissioning of older and exhausted hard coal-fired units. Full article