Search Results (84)

This study investigated the effects of Potentilla fruticosa planting on plant community succession in a spoil heap, analyzed changes in soil enzyme activities under different planting methods, and explored the relationships between soil enzyme activities and plant community diversity across these planting approaches. This experiment selected Potentilla fruticosa planted under different restoration modes (covered with soil, covered with straw curtain, not covered) in Shuanglonggou gangue Mountain, Tianzhu County, Gansu Province, as the research object. The growth status and activities of soil urease, alkaline phosphatase, catalase and sucrase and their correlation were measured in different repair modes in the untreated waste rock (CK). The results showed that (1) the Simpson dominance index and Pielou evenness index decreased to a certain extent under the condition of plant community analysis; Shannon diversity index decreased in the case of curtain covering, but increased in the other two treatments. The richness index of Margalef increased to some extent, and reached the maximum when the curtain was covered. (2) The activity of soil urease and alkaline phosphatase was the lowest in the plots covered by straw curtain, and the activity was 104.4 μg/d/g and 334.5 μg/d/g, respectively. (3) The change in soil catalase activity was not obvious with the increase in soil depth, and the catalase activity in deep soil reached the maximum of 945.3 μg/d/g in the mulch soil sample. (4) The planting of golden dew had a certain effect on the activity of sucrase in shallow soil, and the maximum sucrase activity reached 15.3 μg/d/g under the condition that the planting of Potentilla fruticosa was not covered. (5) Soil urease activity and soil alkaline phosphatase activity were significantly positively correlated with plant community diversity index, while soil catalase activity and soil sucrase activity were negatively correlated with plant community diversity. (6) The total nitrogen content in the soil shows a significant positive correlation with soil urease activity. While soil alkaline phosphatase activity is significantly negatively correlated with soil moisture content, it shows a highly significant positive correlation with soil total nitrogen content. Furthermore, soil sucrase activity demonstrates a highly significant positive correlation with soil bulk density and soil available phosphorus content. To sum up, the planting of golden plum can promote the ecological restoration of gangue mountain soil, and provide a theoretical and scientific basis for ecological restoration and soil quality improvement in the Qilian Mountain mining area. Full article

Zinc metallurgy is one of the large-scale processes that produces tons of waste every year, which in turn generate environmental pollution. In sustainable industry the circular economy is one of the most important issues, which means that as much waste as possible should be reused. Thus, there is a need to find a proper way to use zinc metallurgical waste in some other application. In this paper, an evaluation of the mechanical and tribological properties of an epoxy-based composite filled with zinc metallurgical wastes such as zinc dust, zinc ash and sifted zinc ash has been performed. Results of the research indicated that tensile and impact strength are reduced in all filled compositions. The smallest decrease in strength was observed in the cases of zinc dust and sifted zinc ash in amounts not greater than 5 wt. %. However, wear volume can be reduced by ca. 80% when the epoxy matrix is filled by at least 5 wt. % of zinc ash or sifted zinc ash. So, due to the decrease in mechanical strength and high reduction in wear volume, the most promising among the investigated fillers is sifted zinc ash introduced into the epoxy matrix in an amount up to 5 wt. %. This composition is characterized by a relatively good compromise between the reduction in mechanical strength and reduction in wear volume among investigated cases. Moreover, the reuse of zinc ash as a filler has a positive effect on the environment because of its management of waste stored mainly in heaps, which in turn falls within the scope of the circular economy. Full article

The aim of this paper is to analyze the potential of circular economy in the context of increasing the supply of raw materials for modern economy with particular focus on the role of science and business. The article presents an approach consistent with the concept of sustainable development and fitting in with the implementation of four Sustainable Development Goals: Industry, Innovation, and Infrastructure (SDG 9), Responsible Consumption and Production (SDG 2), Climate Action (SDG 13), and Life on Land (SDG 15). An innovative approach to raw material supply sources is also presented. In addition, the potential of urban mining e-waste in meeting the demand for critical metals is emphasized. The paper presents barriers and challenges for using the potential of raw materials deposited in spoil heaps and landfills or in tailings ponds, with emphasis on the role of modern technologies in increasing the competitiveness of Polish industry. The necessity of a systemic approach to the topic of the circular economy was also emphasized, particularly regarding secondary raw materials as essential for securing critical resources. Full article

Composting represents a sustainable and effective strategy for converting organic waste into nutrient-rich soil amendments, providing a safer alternative to raw manure, which poses significant risks of soil, crop, and water contamination through pathogenic microorganisms. This study, conducted under semi-arid Moroccan conditions, investigated the efficiency of co-composting green garden waste with sheep manure in an open window system, with the objective of assessing pathogen inactivation and evaluating compost quality. The process, conducted over 120 days, maintained thermophilic temperatures exceeding 55 °C, effectively reducing key pathogens including Escherichia coli, total coliforms, Staphylococcus aureus, and sulfite-reducing Clostridia (SRC), while Salmonella was not detected throughout the composting period. Pathogen reductions exceeded 3.52-log despite moderate temperature fluctuations, indicating that additional sanitization mechanisms beyond heat contributed to inactivation. Compost quality, assessed using the CQI, classified Heap 2 (fallen leaves + sheep manure) as good quality (4.06) and Heap 1 (green waste + sheep manure) as moderate quality (2.47), corresponding to differences in microbial dynamics and compost stability. These findings demonstrate that open windrow co-composting is a practical, low-cost, and effective method for safe organic waste management. It supports sustainable agriculture by improving soil health, minimizing environmental and public health risks, and providing guidance for optimizing composting protocols to meet regulatory safety standards. Full article

Forested areas in Poland comprise numerous post-mining sites that hinder effective forest management. Such mining remnants may pose a threat to humans, animals, and operating forest machines. This study aimed to determine the feasibility of inventorying such man-made landforms as mining waste heaps, excavations, remnants of shallow shafts, adits, etc., using the Digital Elevation Model (DEM) based on Airborne Laser Scanning (ALS) data provided by the national agency (the Head Office of Geodesy and Cartography—HOGC) as open data. The DEM, when combined with other cartographic materials using GIS, accurately reflects the anthropogenic transformation evident in the topography. This paper presents the results of inventorying remnants of iron ore mining in the present-day forested area located between Krzepice, Kłobuck, and Częstochowa in southern Poland. The identification and inventory of post-mining landforms, mainly mounds resulting from shallow shaft mining operations, were supplemented by their digitization, automatically providing information on parameters such as perimeter (ranged in most cases from 24.3 to 159 m), surface area (46.9 to 1656 m²), length and width (7.8 to 59.2 m). The heights of the investigated structures were also read from the DEM, ranging from 0.3 to 4.1 m. Much larger structures were also identified, but they occurred accidentally (up to 23.5 m in height). In this manner, approximately 823 morphological forms were characterized, resulting in a database. Test fieldwork was then conducted to verify the DEM readings. It was proposed to calculate deformation indexes (Id [%]) for forested areas and apply them when estimating the forest management hindrance index used by the State Forests. The studied forest compartments managed by State Forests were characterized by an Id value from 0.1 to 55.5%. This type of measure provides a helpful tool in planning forestry operations in areas with diverse topography, including those transformed by mining activities. The actual environmental impact is highlighted. Forest management practices in the study area must take into consideration, in particular, topography, as well as geology and hydrology. Studies have shown that the DEM based on the ALS data is sufficiently accurate to detect even minor post-mining deformations (which may be important, in particular, in inaccessible areas). The recorded parameters can be considered when planning management, protection interventions, or reclamation activities. Full article

Degraded post-mining landscapes require reclamation strategies that ensure soil stability, environmental safety and successful vegetation establishment. This study evaluated two soil cover systems applied between 2020 and 2025 on a mining spoil heap in Libiąż, Poland: a two-layer (TL) cover with a soil substitute layer and a multilayer (ML) cover incorporating additional insulating materials. Both covers were non-saline and mildly alkaline. The applied methods supported favorable soil conditions after five years, with stable organic matter (24.48–28.26%), nitrogen (4.5–4.9 g/kg) and phosphorus (1.5–1.6 g/kg) contents, while potassium decreased markedly (from 17.1 to 6.44–6.83 g/kg), likely due to plant uptake or leaching. Leachate analyses showed low concentrations of toxic metals and salinity-related ions, confirming the environmental safety and inert properties of the soil substitute. Vegetation assessments revealed differences between reclamation systems, with Phragmites australis exhibiting greater stalk length, plant density and biomass in the TL cover. Establishment costs were also substantially lower for TL (EUR 1.65/m²) than for ML (EUR 6.14/m²). These results indicate that soil substitute covers provide a safe, cost-effective and functionally efficient reclamation option that supports circular economy principles by reusing mining waste and coal combustion by-products, while Phragmites australis enhances vegetation development and overall reclamation success. Full article

This study investigates the potential use of black coal mining waste as a feedstock for plasma gasification. A national database of coal waste heaps was developed based on standardized criteria such as heap volume (>100,000 m³), accessibility, and environmental risk. From six initially sampled sites, two active and unreclaimed heaps—Jan Karel (Karviná) and Paskov D (Ostrava)—were selected for detailed material analysis due to their favorable characteristics. Subsequent plasma gasification experiments were conducted using sorted coal waste fractions at a temperature of 1600 °C in a pilot-scale plasma reactor. Four trials were performed with fuel flow rates of 15 and 20 kg/h and varying steam/fuel ratios (0.6, 1.0, and 1.3). The results revealed a high syngas yield of up to 92% by volume. Increasing the steam/fuel ratio led to higher hydrogen and carbon dioxide content in the syngas, while lower ratios favored carbon monoxide and trace methane formation. Volt-ampere characteristics of the plasma torch showed that higher nitrogen flow rates required higher voltage to maintain a stable arc. The findings confirm the technical feasibility and efficiency of converting selected coal mining waste into valuable syngas, supporting its future use in advanced waste-to-energy technologies. Full article

The article presents the results of research and development work conducted as part of the H2GEO project, aimed at creating a comprehensive technology for the processing of post-mining coal waste heaps. The core of the solution is a mobile density separation system based on a pulsating jig, enabling effective recovery of carbonaceous and mineral fractions. Laboratory experiments assessed the impact of key process parameters—such as sieve slot size, pulsation frequency, and enrichment time—on the efficiency and accuracy of separation for different grain size classes. The most favorable results were obtained using a 2.5 mm screen, a pulsation frequency of 60 min⁻¹, and extended enrichment time, which ensured high-quality separation and low ash content in the carbon-bearing product. The findings supported the design of a new industrial separator (jig) equipped with advanced control systems, facilitating the production of homogeneous fractions suitable for further processing into hydrogen, geopolymers, and construction materials. The proposed solution aligns with circular economy principles, promoting waste reuse, environmental hazard mitigation, and the revitalization of degraded post-industrial areas. Full article

Artisanal and Small-Scale Gold Mining (ASGM) is a primary source of global mercury pollution, creating an urgent need for sustainable, low-cost alternatives to amalgamation. This study investigates the use of cassava wastewater (manipueira), a cyanogenic agricultural byproduct, as a lixiviant for a gold concentrate (14.30–15.87 ppm Au) from an artisanal mine. Two approaches were evaluated: direct leaching with manipueira in natura (250 ppm CN⁻) in single and double 8 h and 12 h cycles, and leaching with a cyanide solution concentrated from dilute manipueira (100 ppm CN⁻) via a simplified air-stripping system. Results were benchmarked against the mine’s amalgamation (44.7% recovery) and 30-day heap leach (75.8% recovery) processes. The most effective method observed was a two-cycle, 8 h leach with manipueira in natura, which achieved a mean gold recovery of $76.75\pm 4.71\%$. This result is comparable to the efficiency of the site’s lengthy heap leach process and suggests a promising, faster, route to eliminating mercury use. Longer (12 h) leaching cycles yielded lower recoveries, suggesting process limitations such as preg-robbing. The cyanide concentration method proved inefficient, recovering a maximum of 12.40% of the available cyanide and resulting in a weaker lixiviant. The findings demonstrate that while direct leaching is a viable alternative to mercury, the inherent instability of manipueira necessitates a focus on developing efficient, controlled systems to extract and concentrate its cyanide content, thereby creating a standardized “green” reagent from a large-volume agricultural waste stream. Full article

Revegetation is considered a sustainable option for mine area remediation. However, the sustainability and risk evolution of revegetation for large antimony mine slag remain incompletely understood. In this study, we focused on the revegetation project of the waste slag heap of XKS, the world’s largest antimony mine. Systematically analyzed the physicochemical properties, total metal(loid) content, and BCR sequential extraction and applied the modified comprehensive pollution risk assessment (MCR) method to evaluate ecological risk evolution. The results showed that revegetation can effectively increase the nutrient content, and the total content of nitrogen and phosphorus maximally increased by 5.15 and 1.89 times, respectively, after 10 years of remediation. Long-term revegetation could mitigate the metal(loid) contamination, and the average contents of As and Sb decreased by 88.72–93.18% and 93.47–89.87%, respectively. BCR analysis showed that the percentage of residual As and residual Sb increased from 64.75% and 85.88% to 78.38% and 91.58%, respectively. The MCR assessment method showed that revegetation could effectively reduce the ecological risk level. This study provides important multidimensional evidence for the ecological restoration of antimony mining areas, which can provide practical guidance for subsequent slag management and risk control. Full article

As a legacy of historical metal mining and the processing and smelting of metalliferous ores, metal pollution is a serious environmental problem in many areas around the globe. This review summarizes the history, technical development and environmental hazards of historic metal mining and metallurgical activities in the Harz Region (Germany), one of the oldest and most productive mining landscapes in Central Europe. The release of large amounts of metal-containing waste into rivers during historic ore processing and the ongoing leaching of metals from slag heaps, tailings dumps and contaminated soils and sediments are the main sources of metal pollution in the Harz Mountains and its foreland. This pollution extends along river systems with tributaries from the Harz Mountains and can even be detected in mudflats of the North Sea. In addition to fluvial discharges, atmospheric pollution by smelter smoke has led to long-term damage to soils and vegetation in the Harz Region. Currently, the ecological hazards caused by the legacy pollution from historical metal mining and metallurgy in the Harz Region are only partially known, particularly regarding the effects of changes in river ecosystems as a consequence of climate change. This review discusses the complexity and dynamics of human–environment interactions in the Harz Mountains and its surroundings, with a focus on lead (Pb) pollution. The paper also identifies future research directions with respect to metal contamination. Full article

Active and abandoned mining sites are significant sources of heavy metals and metalloid pollution, leading to serious environmental issues. This study assessed the environmental risks posed by potentially toxic elements (PTEs), specifically arsenic (As) and antimony (Sb), in the Technosols (mining residues) of the former Pejão coal mine complex in Northern Portugal, a site impacted by forest wildfires in October 2017 that triggered underground combustion within the waste heaps. Our methodology involved determining the “pseudo-total” concentrations of As and Sb in the collected heap samples using microwave digestion with aqua regia (ISO 12914), followed by analysis using hydride generation-atomic absorption spectroscopy (HG-AAS). The concentrations of As an Sb ranging from 31.0 to 68.6 mg kg⁻¹ and 4.8 to 8.3 mg kg⁻¹, respectively, were found to be above the European background values reported in project FOREGS (11.6 mg kg⁻¹ for As and 1.04 mg kg⁻¹ for Sb) and Portuguese Environment Agency (APA) reference values for agricultural soils (11 mg kg⁻¹ for As and 7.5 mg kg⁻¹ for Sb), indicating significant enrichment of these PTEs. Based on average I_geo values, As contamination overall was classified as “unpolluted to moderately polluted” while Sb contamination was classified as “moderately polluted” in the waste pile samples and “unpolluted to moderately polluted” in the downhill soil samples. However, total PTE content alone is insufficient for a comprehensive environmental risk assessment. Therefore, further studies on As and Sb fractionation and speciation were conducted using the Shiowatana sequential extraction procedure (SEP). The results showed that As and Sb levels in the more mobile fractions were not significant. This suggests that the enrichment in the burned (BCW) and unburned (UCW) coal waste areas of the mine is likely due to the stockpiling of lithic fragments, primarily coals hosting arsenian pyrites and stibnite which largely traps these elements within its crystalline structure. The observed enrichment in downhill soils (DS) is attributed to mechanical weathering, rock fragment erosion, and transport processes. Given the strong association of these elements with solid phases, the risk of leaching into surface waters and aquifers is considered low. This work underscores the importance of a holistic approach to environmental risk assessment at former mining sites, contributing to the development of sustainable remediation strategies for long-term environmental protection. Full article

Pollution in mining areas represents a major environmental issue, significantly impacting ecosystems and human health. This study highlights propolis as an efficient natural bioindicator for detecting and assessing the degree of contamination in these areas. The objective of this study is to determine the levels of metals (Pb, Cd, As, Cr, Fe, Mn, Cu, and Zn) in propolis from mining exploitation areas in Romania, specifically in the counties of Alba, Hunedoara, Maramureș, and Caraș-Severin. Although mining operations are closed, the anthropogenic impact varies due to differences in the surface areas of the zones affected, the areas occupied by waste heaps, local hydrological conditions, and partial ecological rehabilitation efforts. To highlight the impact of contamination, a reference area considered unaffected by anthropogenic activities was used as a benchmark for each county. The values obtained in the investigated area were compared with those from this control zone to determine the differences and the specific impact of pollution. Maximum values were recorded in Roșia Montană for Pb (9.27 mg·kg⁻¹), Cd (0.17 mg·kg⁻¹), and As (0.87 mg·kg⁻¹); in Băile Borșa for Fe (150.23 mg·kg⁻¹) and Zn (2.9 mg·kg⁻¹); in Certeju de Sus for Cu (6 mg·kg⁻¹) and Cr (7.01 mg·kg⁻¹); and in Moldova Nouă for Mn (25.43 mg·kg⁻¹). The maximum content values of phenols (189.49 mg·kg⁻¹ in Alba County) and flavonoids (88.06 mg·kg⁻¹ in Caraș-Severin) were recorded, as well as the minimum IC₅₀ antioxidant activity (0.33 µg·mL⁻¹). Propolis from these areas showed antimicrobial activity against five bacterial strains (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, and Streptococcus mutans) and five fungal strains (Candida albicans, Aspergillus niger, Aspergillus flavus, Cryptococcus neoformans, and Penicillium chrysogenum), although such antimicrobial and antifungal activities were more intense in unpolluted areas. The present study reveals that propolis is a natural indicator of heavy metal pollution in mining areas. These data support the usefulness of propolis due to its high capacity to accumulate and reflect environmental contaminants. Full article

Metal-mining activities inevitably generate contaminants in high quantities, which can pose a risk to soil, water, biota, and humans. This study compares the geochemical properties of waste materials of tailings and waste rock heaps originating from the same high-sulfidation-type epithermal mineralization. Field sampling was conducted in the Recsk Copper Mining Area on the H2 tailings and H7 waste heap, where a total of 48 samples were collected at various depths. The results showed that PTEs were present in varying concentrations and behaved differently in the two waste materials. Copper concentrations were approximately five times higher in H2 tailings (median 1660 mg/kg) than in H7 waste rock (median 347 mg/kg), whereas arsenic was 2.8 times more concentrated in H2 tailings (674 mg/kg vs. 238 mg/kg). Conversely, zinc (114 mg/kg vs. 24 mg/kg), lead (172 mg/kg vs. 42.8 mg/kg), and cadmium (0.83 mg/kg vs. 0.097 mg/kg) show significantly higher concentrations in H7 waste rock. Element mobility analyses revealed that calcium mobility in H7 waste rock (65%) was twice that observed in H2 tailings (32%), with copper showing a threefold higher mobility in H7 despite lower total concentrations. NAG pH values (2.06–3.23) confirmed significant acid-generating potential in both waste types, with the H7 waste rock posing greater immediate environmental risk due to higher element mobility and more advanced weathering indicated by elevated jarosite (4.05%–8.01%) and secondary mineral contents. These findings demonstrate that, despite originating from the same mineralization, the distinct processing histories and physical properties of these materials necessitate unique approaches for successful remediation or secondary raw material extraction. 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