Search Results (40)

The Maramures region, located in North-Western Romania, was a renowned center of mining and smelting in the last century. Nowadays, all the mines have been decommissioned or are under conservation and greening works, but the acidic waters from some closed or abandoned mine galleries negatively affect the nearby streams and, in some cases, the entire river system. In this study, 46 elements and 6 anion concentrations were used to assess the pollution in 12 mine water discharge samples collected in two mining areas in Maramures. The results showed high concentrations of sulfate (average 1264 mg/L) and toxic elements, namely Mn (average 25.1 mg/L), Fe (average 23.0 mg/L), and Zn (average 12.5 mg/L). The sum of the REEs concentration ranged from 1.24 µg/L to 2917 µg/L, with an average of 363 µg/L, with La, Ce, and Nd being the most abundant. High correlations were found between REEs and Li, Be, Al, Sc, V, Mn, Fe, Co, Ni, Y, SO₄²⁻, and NO₂⁻. According to the pollution index, the discharge of mine water poses different degrees of ecological risk. The health hazard index calculated for 37 elements revealed an extremely high non-cancer risk and, in addition, an increased carcinogenic risk for Cd, As, and Cr. Full article

The settlement and deformation of abandoned mining tunnels can lead to cracking, deformation, or even the collapse of surface structures. Recently, a dual-direction, four-lane expressway, designed a speed of 100 km/h, is planned to be constructed between Yuanling County and Chenxi County. This expressway will pass through a long-abandoned refractory clay mining area in Chenxi County. This study focuses on this abandoned mining area and employs the Electrical Resistivity Tomography (ERT) method to investigate the underground conditions, aiming to determine the location and scale of the subterranean goaf. A total of five survey lines were deployed for the investigation. The inversion results indicate the presence of five low-resistivity anomalies in the underground structure (with six low-resistivity anomalies identified along line L1). These low-resistivity anomalies are preliminarily interpreted as subsurface cavities. Subsequent borehole verification revealed that the five low-resistivity anomalies correspond to a total of eight water-filled cavities, including six abandoned mining tunnels and two karst caves. At the location K33+260~K33+350, a large low-resistivity anomaly was identified which actually consisted of three closely spaced water-filled abandoned mining tunnels. Additionally, the surrounding strata primarily consisted of fractured mudstone, which has a high water content and thus exhibits low resistivity. These two factors combined resulted in the three water-filled abandoned mining tunnels appearing as a single large low-resistivity anomaly in the inversion profile. Meanwhile, at K33+50~K33+110, two water-filled abandoned mining tunnels were found. These tunnels are far apart along line L1 but are relatively close to each other on the other four survey lines. Consequently, in the inversion results, line L1 displays these as two separate low-resistivity anomalies, while the other four survey lines show them as a single large low-resistivity anomaly. Based on the 2D inversion results, a 3D model of the study area was constructed. This model provides a more intuitive visualization of the underground cavity structures in the study area. The findings not only serve as a reference for the subsequent remediation of the goaf area but also offer new insights into the detection of abandoned mining tunnels. Full article

As a mining country, China faces enormous challenges in the context of the global commitment to achieve carbon neutrality. In order to achieve this goal, the Chinese government is actively promoting the green and low-carbon transformation of the energy system. Consequently, an increasing number of mines with poor production capacity and depleted resources are being closed down or eliminated, leading to a large quantity of stranded land resources that are now idle. However, in the process of rapid economic development, China is facing serious problems, such as land shortage and land use conflicts. Abandoned mining land (AML), as a kind of reserve land resource, has an important regulating role in solving the dilemma of land resource tension faced by national land spatial planning. In order to realize the rational planning and utilization of AML, this study proposes a high-precision AML planning model and simulates the planning of AML in multiple policy scenarios, using Ningbo City as an example. The results show that AML has great economic and ecological potential; the economic development scenario (EDS) enhanced the economic benefits of the mine region by 396%, and the ecological protection scenario (EPS) enhanced the ecological benefits of the mine region by 74.61%, when compared with the baseline scenario (BAU). The overall level of optimization is as follows: EDS > EPS > BAU. In addition, the optimal utilization of AML in all three scenarios significantly enhanced the ecological quality of the mining region, and the enhancement effect was EPS > BAU > EDS. Therefore, AML, as a kind of free land resource, has an important supporting effect for the spatial planning of the national territory. Furthermore, it is of great significance to scientifically and reasonably guide the optimal utilization of AML, according to the policy planning for future development, in order to achieve efficient economic development and improve the quality of the ecological environment. Full article

In recent years, the prolonged exploitation of coal resources has led to the depletion of coal reserves in some mining areas, resulting in the closure of certain mines worldwide. After mine closures, the fractured rock masses in abandoned mine cavities undergo weathering and degradation due to factors such as stress and groundwater, leading to reduced strength. This change alters the stress distribution and load-bearing capacity of the fractured rock within the abandoned voids, resulting in secondary or multiple deformations on the surface, which pose significant potential threats to surface infrastructure and public safety. Research into the mechanisms, patterns, and predictive methods of secondary surface subsidence in closed mines is thus of great theoretical and practical significance. Based on a literature review and practical monitoring experience in closed mine sites, this study systematically examines and analyzes the current state of secondary surface subsidence monitoring methods, formation mechanisms, spatiotemporal distribution patterns, and prediction methods in closed mines, as well as existing challenges. Initially, we compare the advantages and limitations of conventional surface deformation monitoring techniques with remote sensing techniques, emphasizing the benefits and issues of using InSAR technology for monitoring surface subsidence in closed mines. Next, by reviewing extensive data, we analyze the formation mechanisms and spatiotemporal evolution of secondary surface subsidence in closed mines. Building on this analysis, we discuss numerical and analytical methods for predicting secondary surface subsidence mechanisms in closed mines, evaluating the strengths and weaknesses of each approach. Predictive models for surface subsidence and uplift phases in the longwall collapse method are presented based on the constitutive relationships of fractured rock masses. Finally, the study highlights that the mechanisms and patterns of surface subsidence in closed mines represent a highly complex physical–mechanical process involving geological mining environments, fractured rock structures, constitutive relations, deformation characteristics, hydro-mechanical interactions, and groundwater dynamics, underscoring the need for further in-depth research. Full article

Acid mine drainage (AMD) forms in mining areas during or after mining operations cease. This is a primary cause of environmental pollution and poses risks to human health and the environment. The hydrographic system from the Maramureș mining industry (especially the Baia Mare area) was heavily contaminated with heavy metals for many years due to mining activity, and after the closing of mining activity, it continues to be polluted due to water leaks from the abandoned galleries, the pipes, and the tailing ponds. The mineralization in the Băiuț area, predominantly represented by pyrite and marcasite associated with other sulfides, such as chalcopyrite, covelline, galena, and sphalerite, together with mine waters contribute to the formation of acid mine drainage. The Breiner-Băiuț mining gallery (copper mine) permanently discharges acidic water into the rivers. The efficiency of iron scrap (low-cost absorbent) for the treatment of mine water from this gallery was investigated. The treatment of mine water with iron shavings aimed to reduce the concentration of toxic metals and pH. Mine water from the Breiner-Baiut mine, Romania, is characterized by high acidity, pH = 2.75, and by the association of many heavy metals, whose concentration exceeds the limit values for the pollutant loading of wastewater discharged into natural receptors: Cu—71.1 mg/L; Zn—42.5 mg/L; and Fe—122.5 mg/L. Iron scrap with different weights (200 g, 400 g, and 600 g) was put in contact with 1.5 L of acid mine water. After 30 days, all three treatment variants showed a reduction in the concentrations of toxic metals. A reduction in Cu concentration was achieved below the permissible limit. In all three samples, the Cu concentrations were 0.005 for Sample 1, 0.001 for Sample 2, and <LOQ for Sample 3. The Zn concentration decreased significantly compared to the original mine water concentration from 42.5 mg/L to 1.221 mg/L, 1.091 mg/L, and 0.932 mg/L. These values are still above the permissible limit (0.5 mg/L). The Fe concentration increased compared to the original untreated water sample due to the dissolution of iron scrap. This research focuses on methods to reduce the toxic metal concentration in mine water, immobilizing (separating) certain toxic metals in sludge, and immobilizing various compounds on the surface of iron shavings in the form of insoluble crystals. Full article

Ecological networks are an effective strategy to maintain regional ecological security. However, current research on ecological network construction in areas with large-scale resource extraction is limited. Moreover, classic ecological network construction methods do not perform satisfactorily when implemented in heavily damaged mining landscapes. Taking the example of Liaoning Province, China, a framework for stepwise renewal of ecological networks was proposed, which integrates basic ecological sources and other sources that include mining areas. The framework was based on multi-source ecological environment monitoring data, and all potential ecological sources were extracted and screened using an MSPA model and the area threshold method. Further, ecological sources were classified into two types and three levels based on the influence of abandoned mines and the characteristics of ecosystem services in the ecological sources. Ecological corridors were extracted using the MCR model. An ecological corridor optimization process based on combining the gravity model with addition and removal rules of corridors was proposed. The results indicated that the basic ecological network in Liaoning Province included 101 ecological sources and 162 ecological corridors, and the supplementary ecological network included 28 ecological sources and 67 ecological corridors. The ecological sources were divided into two types, and corridors were divided into three types. The basic ecological network exhibited a spatial distribution of discrete connections in the west and close connections in the east. Changes in ecological network topological indicators indicated that a supplementary ecological network strengthened the structural performance of the regional ecological network, expanding spatial coverage, filling hollow areas, and enriching local details of the regional ecological network. Regulation strategies were proposed for ecological sources with different connection modes. The number of ecological sources implementing restrictive development, pattern optimization, and protective development were 101, 12, and 16, respectively. This paper provides a constructing framework of ecological networks adapted for resource-based regions. This method can support decisions for the environmental governance of mines, thus contributing to a balance between resource exploitation and ecological protection in regions. Full article

In accordance with the programme of closure works and the implementation of ecological spatial rehabilitation in the area of the Slovenian coal mine Trbovlje–Hrastnik (RTH), there is a great opportunity to exploit shallow geothermal energy from water and ground sources. In the RTH area, there is great energy potential in the utilisation of underground water and heat from the earth. In our research, we have focussed on the use of geothermal energy with heat pumps from groundwater (water/water system) and from ground collectors and wells up to a depth of 150 m (rock/water system). With the water/water system, we have an average of 2.7 MW of thermal energy available, with the rock/water system having 7.5 kW of thermal energy from a 150 m deep well. With the rock/water system in particular, the development of an industrial zone in the RTH area can also provide for a greater demand for thermal energy. The thermal energy obtained in this way is utilised via heat pumps to heat and cool commercial, residential and industrial buildings. The utilisation of shallow geothermal energy can make a major contribution to carbon neutrality, as the use of geothermal energy has no negative impact on the environment and causes no greenhouse gas emissions. The aim of the paper is to provide an overview of the methods used to analyse heat storage in aquifers of abandoned coal mines, to represent these storages in RTH with a basic mathematical–statistical inventory of what is happening in the aquifer, and to investigate the possibility of using shallow geothermal energy with the help of modelling the use of shallow geothermal energy. The results and analyses obtained can make an important scientific contribution to the use of geothermal energy from abandoned and closed mines. Full article

The mineral raw materials industry is crucial for European industry, with the European Economic and Social Committee estimating that 70% of the industry relies directly or indirectly on its supply. In the context of a decarbonized and digitalized economy, the new European industrial model requires carbon-neutral raw materials and production processes. The crucial role of aggregates mining, as the primary construction material, emerges as a key supplier in this paradigm. Aggregates are the main component of the built environment and are a social and economic engine in most countries. Quarries of this type include a wide range of sizes and exploitation methods and use characteristic mining and processing equipment. Quarries are commonly close to their processing plants, which transform natural rock into crushed and ground materials with different grain sizes depending on the future uses. The quarry itself and the presence of certain equipment and facilities help distinguish it from mining sites that exploit other materials. Effective management of aggregates quarries is important in promoting circular economy practices, ensuring efficient management, reuse, and recycling of diverse wastes, including the recovery of high-value components and the production of recycled aggregates, and addressing construction and demolition waste (DCW) management. As aggregates become a progressively scarcer resource due to the increasing demand from developing countries, it is essential to provide reliable and comprehensive information on their potential to the public, policymakers, and other stakeholders to promote their use. This study focuses on employing artificial intelligence and computer vision analysis to automatically identify aggregates quarries from satellite images within continental Spain. A model has been trained to detect aggregates quarries from satellite images by computer vision. The model permits the detection of mining exploitation and the objects located at the interior, which permits determination of the type of mine and the activity status of it. The findings highlight the ability of artificial vision to discern quarries and distinguish whether the observed feature is an aggregates quarry. Additionally, the technology allows for the determination of the quarry’s operational status, distinguishing between active and abandoned quarries. The ability to detect the locations of quarries and assess their activity statuses is of significant value for resource exploration initiatives and location-allocation assessments. It can be a valuable tool for authorities involved in land planning, activities monitoring, and early detection of potential illegal mining activities. This analytical approach demonstrates substantial potential for various stakeholders, including mining companies, mining authorities, policymakers, and land use planners in both the private and public sectors. Full article

Critical and Strategic Raw Materials European Union’s policies are targeting the production of fundamental raw materials from internal sources, fostering the recovery of relevant quantities of materials from the existing mining facilities in Europe. Northwest Italy was an important mining area until the mid-1900s, as reported by the Italian inventory of closed mining waste storage facilities, referring to 92 mining waste facilities. Three sites were chosen to better define their historical and bibliographical framework. The selected sites comprise the Traversella Mine (Piedmont), Libiola Mine (Liguria) and Herin Mine (Aosta Valley). Currently, there are relevant amounts of abandoned mining waste in the surrounding areas of these closed mines. The potential recovery of the residual valuable fraction of these materials could be crucial for both critical raw materials’ recovery and environmental valorization of the involved territories. Full article

As Europe addresses decarbonization, huge coal mining areas shall be reclaimed and appropriately valorized, creating the post-mining areas. This work assesses their resilience and safety by methodologically addressing multi-hazards threatening closed and abandoned mines. The current work modifies an indicator-based semi-quantitative multi-hazard method towards post-mining risk assessment, described as the (1) identification of the hazards, (2) assessment of the interactions, and (3) quantification of the level of interactions. The methodology can appropriately quantify the multi-hazard severity for various scenarios. However, it has limitations, not considering appropriately the hazards’ sequence and missing an objective criterion for scenario comparison. Full article

Backfill materials of various origin and composition, abandoned machinery, oils, PCB, gallery support material and cables are the main wastes occurring in underground coal mines during the period of their abandonment. Bearing in mind that under increasing societal pressure most if not all underground coal mines are going to close sooner rather than later, it is important to understand the interactions of these waste materials with rising mine water during mine water level rebound to prevent adverse environmental effects, especially on surface and groundwater. To this end, the composition of mine water at decant points as well as the hydrogeochemical, temporal and spatial dynamics of mine water during rebound requires quantification. In the first part of this paper, an overview of waste materials in underground coal mines is presented. The second part focusses on the experiences gained in the Ruhr area, a closed underground coal mining region in western Germany, where mine water rebound has been ongoing for decades. In this regard, the mine water modeling program Boxmodell was applied during regulatory approval procedures to predict the hydrodynamics and hydrogeochemical development of the water rebound. The results of these investigations allow deep insights into the interactions of rising mine water with wastes as well as the complex chemical evolution of mine water and potentially occurring contaminants (e.g., PCB). The experiences regarding wastes in underground coal mines and the geochemical evolution of rising mine water gained in the Ruhr area can be utilized to support the planning of mine closure in currently still active underground coal mining areas worldwide. Full article

With climate change, more intense weather phenomena can be expected, including pressure drops related to the arrival of an atmospheric front. Such drops of pressure are the main reason for gas emissions from closed mines to the surface, and a closed, empty mine shaft is the most likely route of this emission. Among the gases emitted, the most important are carbon dioxide and methane, creating a twofold problem—greenhouse gas emissions and gas hazards. The work presented in this paper simulated the spread of the mentioned gases near such an abandoned shaft for four variants: model validation, the most dangerous situations found during measurements with or without wind, and a forecast variant for a possible future pressure drop. It was found that a momentary CO₂ emission of 0.69 m³/s and a momentary CH₄ emission of 0.29 m³/s are possible, which for one hour of the appropriate drop would give hypothetically 2484 m³ CO₂ and 1044 m³ CH₄. In terms of gas hazards, the area that should be monitored and protected may exceed 25 m from a closed shaft in the absence of wind influence. The wind spreads the emitted gases to distances exceeding 50 m but dilutes them significantly. Full article

Acid mine drainage originates from mining waste, tailings and overburden being exposed to air and water; it is also observed in abandoned mines, characterized by high acidity and increased concentrations of sulfate and heavy metals. It is considered a notorious pollutant, mostly affecting superficial and ground water quality. Until 1977, Lavrion mines have been the heart of dynamic Greek mining and extractive metallurgy. The present paper discusses the possibility of using low-cost eco-friendly materials, i.e., natural and synthetic zeolites for the in situ rehabilitation of Lavrion mine soil. Na-P1 synthetic zeolite prepared from Meliti fly ash and two natural zeolites from Samos tuffs mostly containing clinoptilolite and mordenite, respectively, were employed. The results indicated that all three aluminosilicates alleviated two basic soil parameters closely correlated with fertility, i.e., high acidity and low CEC. Regarding toxic metals leaching, Na-P1 synthetic zeolite proved more efficient, reducing heavy metal contents in the leachates by 38%, 72%, 61%, 67%, 77% and 33% for Pb, Cd, Zn, Cu, Mn and Fe, respectively. This was attributed to both the increased pH and CEC values of the Na-P1 zeolite. Between the Samos zeolites, the richest in mordenite exhibited the better performance. Full article

Many regions of the United States contain manganese deposits economically valuable in New England, Appalachian, and Piedmont regions in the Eastern United States, in Northern Arkansas, and, to a small extent, in Central–Western California. Mn oxide/hydroxide (commonly referred to as Mn oxide minerals) are found in a wide variety of geological settings and occur as fine-grained aggregates, veins, marine and freshwater nodules and concretions, crusts, dendrites, and coatings on rock surfaces (e.g., desert varnish). How manganese oxides form and what mechanisms determine which oxides are likely to form are limited and still debated. This paper focuses on Mn oxides collected at the southern bound of the abandoned open-pit site called Crimora Mine (Augusta County, Virginia). This study uses mineralogical and chemical features to shed light on the origin of manganese deposits in Crimora along the western foot of the Blue Ridge in South–West Virginia. We report the first detailed study on the genesis of the Crimora manganese deposit conducted since the mine was closed in the 1950s. Crimora Mine sample is dark black fine- to medium-grained round and oblong nodules coated with a fine-grained intermix of yellowish earthy limonite, clays, and quartz. Scanning electron microscopy (SEM) revealed that the Crimora Mn-oxides exhibit concentric layering, breccia-like matrices, and veins. X-ray powder diffraction (XRPD) identified the set of Mn minerals as hollandite and birnessite. The concentration and range of dissolved chemical species in freshwater, seawater, and hydrothermal depositional fluids impart a geochemical signature to the Mn-oxides, providing a diagnostic tool to shed light on their genetic origin. Inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the Crimora manganese oxides shows Mn, Fe, and Ti, as well as trace elements such as Co, Ba, Y, Zn, Cr, Ni, Tl, La, V, and Li. A bivariate analysis based on the geochemical correlation of Mn and other common substituting cations (e.g., Fe, Co, Ti) shows a mixed genesis in different environments with varying biological and sedimentary supergene (freshwater and marine) conditions. These data suggest that the Mn-rich deposit in Crimora, VA, was formed in a continental margin environment of surficial deposits and reprecipitated in mixed biogenic and supergene conditions. Full article

An abandoned sphalerite mining area in the southwest (SW) of the Iberian Peninsula was studied to evaluate the impact that the presence of metal(loid)s has on soil and ecosystem health. Five zones were delimited: sludge, dump, scrubland, riparian zone, and dehesa. Critical total levels of lead (Pb), zinc (Zn), thallium (Tl), and chromium (Cr), well above the limit indicative of toxicity problems, were found in the areas close to the sources of contamination. Pb-Zn concentrations were very high in the riparian zone, reaching values of 5875 mg/kg Pb and 4570 mg/kg Zn. The whole area is classifiable as extremely contaminated with Tl, with concentrations above 370 mg/kg in the scrubland. Cr accumulation mainly occurred in areas away from the dump, with levels up to 240 mg/kg in the dehesa. In the study area, several plants were found growing luxuriantly despite the contamination. The measured metal(loid)s content is the cause of a significant decrease in ecosystem services, resulting in unsafe soils for food and water production, so the implementation of a decontamination program is advisable. The plant species Retama sphaerocarpa, present in the sludge, scrubland, riparian zone, and dehesa, is postulated as suitable for use in phytoremediation. Full article