Sustainable Post-Mining Land Use: Are Closed Metal Mines Abandoned or Re-Used Space?

Air quality in post-mining towns: tracking potentially toxic elements using tree leaves

In this study, leaves of the evergreen holm oak Quercus ilex were used to assess airborne contamination of potentially toxic elements (PTEs) at five towns located on the slopes of the Mt. Amiata (central Italy), an area with a long history of mining and, more recently, an important district for the industrial exploitation of geothermal energy. PTE composition and covariance of washed and unwashed Q. ilex leaves of three different ages (6, 12 and 24 month-old) were used to identify atmospheric inputs of PTEs at residential areas, evaluate long-term adsorption and retention of PTEs by the leaves, thus providing an indication of potential human exposure. Moreover, the determination of foliar concentrations of major elements (C, N, S and P) allowed an assessment of the nutritional status of the investigated urban tree stands which excluded the existence of stress condition caused by air pollution or other disturbances. Results indicated that overall Pb, Cu, and Cd concentration were low in the investigated urban sites, if compared with similar studies conducted in larger Italian cities, denoting a low contribution of vehicular traffic to the atmospheric pathway. The five urban settlements were characterized by a specific profile of elements (Al, Ba, Hg and Sb) enriched in unwashed leaves, resulting from the distinct geochemical characteristics of the area and from diffuse (i.e., urban activity) and point sources of PTEs emission (i.e., brownfields, geothermal power plants). The latter sources primarily govern the distribution of Hg, whose contamination was found to be very localized close to a major abandoned mining area. Our data provided quantitative evidence of the spectrum of PTEs potentially impacting resident population and may prove useful in support of follow-up instrumental monitoring campaigns of air quality, as well as for human health and ecological risk assessments.

Mapping knowledge domains for mine heat hazard: a bibliometric analysis of research trends and future needs

As the shallow mineral resources are nearly depleted, the mining of deep resources has become an urgent problem to be studied. The increase in mine depth can lead to the increase of mine heat hazard, which is a critical concern for mining safety/occupational health and safety. However, there are limited review articles available regarding the prevention of mine heat hazard. To fill in this gap, a bibliometric analysis and knowledge mapping of the field of mine heat hazard prevention are presented in this paper. A total of 314 papers from the Web of Science (WOS) core collection database that published between January 1998 and July 2022 were analyzed using VOSviewer and CiteSpace. China, South Africa, Poland, USA, and Australia are the top five countries in this field. The important journals are Applied Thermal Engineering, Applied Energy, Energies, and International Journal of Mining Science and Technology. In addition, the research focal points and two research fronts were identified and discussed. The knowledge base of mine heat hazard research focuses on mine cooling technology, energy efficiency optimization of cooling systems, thermodynamic theory, and occupational health. There are two research fronts. One is to use the numerical simulation method to study various problems such as simulate the performance of refrigeration systems and thermal comfort in mines. The second is to study the occupational health impact of climate change on miners. Therefore, this paper provides readers and academics with an overview of the intellectual structure and knowledge body that have been developed on the subject of mine heat hazard.

Using POI and time series Landsat data to identify and rebuilt surface mining, vegetation disturbance and land reclamation process based on Google Earth Engine

The development of coal resources is necessary, but it has a huge negative impact on land, ecology, and the environment. With the increasing awareness of environmental protection and the requirements of related regulations, the design and practice of reclamation projects run through the mining life cycle and continue for a long time after the coal production. High-precision monitoring of mining disturbance and reclamation, quantifying the degree and time of vegetation disturbance and restoration, is of great significance to minimize the environmental effect of mining. Remote sensing, widely used as efficient monitoring tool, but there is not enough research on disturbance and reclamation monitoring taking into account large-scale areas and high temporal and spatial accuracy. Especially when mining sites remain unknown, how to distinguish the disturbance of coal mining and other human activities affecting the surface land cover has become a challenge. Therefore, this paper proposed a method to reconstruct the time series of mining disturbance and reclamation in a large area by using the POI (point of interest) and Landsat time series images using multiple buffer analysis methods. The process includes: (1) Retrieval of POI in the study area based on the public mining list using Python crawler, and buffering 100 km for preliminary extraction of potential mining areas; (2) Using spectral index mask and random forest algorithm to accurately extract the exposed coal on the Google Earth Engine (GEE) platform; (3) Buffering 10 km to identify the occurrence of disturbance and reclamation, using pixel-based temporal trajectory identification of LandTrendr algorithm under GEE. The method successful detect the change points of surface coal mining disturbance and reclamation in eastern Inner Mongolia of China. The results show that: (1) The method can effectively identify the extent of surface coal mining disturbance and reclamation, and the overall extraction accuracy is 81%. (2) Surface coal mining disturbance in eastern Inner Mongolia was concentrated in 2006-2011. By 2020, the total disturbed area is 627.8 km², with an average annual disturbance of 18.5 km², and the annual maximum disturbance to the ground reached 64.6 km² in 2008. With the total reclaimed area being 236.3 km², the reclamation rate is about 37.6%. This study provides a systematic solution and process for monitoring the disturbance and reclamation of surface coal mining in a large range with little known about the mines' location. It can effectively identify the mining disturbance and reclamation process which can also be extended to other areas, providing a quantitative assessment of mining disturbance and reclamation, which can support further ecological restoration decision-making.

Carbon dioxide sequestration of iron ore mining waste under low-reaction condition of a direct mineral carbonation process

Mining waste that is rich in iron-, calcium- and magnesium-bearing minerals can be a potential feedstock for sequestering CO₂ by mineral carbonation. This study highlights the utilization of iron ore mining waste in sequestering CO₂ under low-reaction condition of a mineral carbonation process. Alkaline iron mining waste was used as feedstock for aqueous mineral carbonation and was subjected to mineralogical, chemical, and thermal analyses. A carbonation experiment was performed at ambient CO₂ pressure, temperature of 80 °C at 1-h exposure time under the influence of pH (8-12) and particle size (< 38-75 µm). The mine waste contains Fe-oxides of magnetite and hematite, Ca-silicates of anorthite and wollastonite and Ca-Mg-silicates of diopside, which corresponds to 72.62% (Fe₂O₃), 5.82% (CaO), and 2.74% (MgO). Fe and Ca carbonation efficiencies were increased when particle size was reduced to < 38 µm and pH increased to 12. Multi-stage mineral transformation was observed from thermogravimetric analysis between temperature of 30 and 1000 °C. Derivative mass losses of carbonated products were assigned to four stages between 30-150 °C (dehydration), 150-350 °C (iron dehydroxylation), 350-700 °C (Fe carbonate decomposition), and 700-1000 °C (Ca carbonate decomposition). Peaks of mass losses were attributed to ferric iron reduction to magnetite between 662 and 670 °C, siderite decarbonization between 485 and 513 °C, aragonite decarbonization between 753 and 767 °C, and calcite decarbonization between 798 and 943 °C. A 48% higher carbonation rate was observed in carbonated products compared to raw sample. Production of carbonates was evidenced from XRD analysis showing the presence of siderite, aragonite, calcite, and traces of Fe carbonates, and about 33.13-49.81 g CO₂/kg of waste has been sequestered from the process. Therefore, it has been shown that iron mining waste can be a feasible feedstock for mineral carbonation in view of waste restoration and CO₂ emission reduction.

The influence of Strzelin Quarry Lakes on small reservoir retention resources in the regional catchments

The paper presents the results of the analysis of the volume of water retained in Strzelin Quarry Lakes (SQLs). The volume of retained water was estimated by using the computational method, where the proposed reduction factors were determined with the use of DTM (digital terrain model). 2.6 hm³ of water was retained in seventeen Strzelin Quarry Lakes, of which 1.2 hm³ in the Ślęza River catchment (3 quarry lakes), and 1.4 hm³ in the Oława River catchment (14 quarry lakes). The obtained data of the volume of water retained in SQLs were compared to the balance of the water retention capacity of water reservoirs in the catchments of the Ślęza River (0.809 hm³), part of the WR08 Bystrzyca balance catchments (16.190 hm³) and in the catchments of the Oława River (2.782 hm³), part of the WR09 Nysa Kłodzka balance catchment (104.960 hm³). Inclusion the volume of water retained in Strzelin Quarry Lakes in the small scale water retention (reservoirs and ponds) balance would increase the volume of retained water by 156.0% in the Ślęza catchment (by 7.8% in the WR08 Bystrzyca balance catchment) and by 49.5% in the Oława catchment (by 1,3% in the WR09 Nysa Kłodzka balance catchment). Under favorable hydrogeological and geomorphological conditions water reclamation of the excavations may be one of the main aspects of increasing the retention capacity of the catchment, what is particularly important in areas characterized by low water resources.

A Methodology Combining IDEF0 and Weighted Risk Factor Analysis for the Strategic Planning of Mine Reclamation

The reclamation of lignite surface mines is a long-term commitment of high complexity. These reclamation projects consist of land use repurposing, reinstatement of landforms and landscape, remediation of polluted soils and water bodies, restoration of ecosystems, and other related activities, which are usually developed when mines enter the ultimate phase of their operational life. Nowadays, reclamation is supported by regulatory settings and legislative provisions, which motivate the affected communities to move towards a circular economy and sustainable development. This paper investigates the geoenvironmental and socioeconomic problems of reclamation and draws research questions on how the strategic planning of a reclamation project can be performed and how the relevant project risks can be investigated and managed. In turn, a prototype methodology based on experts’ judgment is suggested with a case study combining: (a) the IDEF0 (Integrated DEFinition Function) modelling technique, as a low cost and easy-to-develop tool enabling strategic planning of reclamation projects, and (b) the Weighted Risk Factor analysis as a suitable method for effective risk analysis and response planning in post-mining frameworks. Finally, a discussion on the methodology and proposals for further research are provided.

The Economic Situation of Polish Cities in Post-Mining Regions. Long-Term Analysis on the Example of the Upper Silesian Coal Basin

The purpose of this article is to identify the long-term economic consequences of mine decommissioning for five selected cities located in Poland in the Upper Silesian Coal Basin. It is carried out over a period of 18 years and covers the period 2003–2020. The economic effects of decommissioning are examined in the context of the budgets of cities where mining plants were closed. In the course of the analyses, the authors of the article attempt to answer the following research questions: (1) has the decommissioning of the mines influenced the current and strategic situation of the examined cities in terms of their budgets? (2) Have the examined cities felt the economic effects of mine decommissioning in a similar way? The assessment of the economic effects of mine decommissioning was carried out from the following two perspectives: (1) operational, relating to the balance of local budgets, and (2) strategic, taking into account the level of long-term liabilities of the examined cities. As part of the research methodology, budget analysis, descriptive statistics, dynamics and trends analysis, correlation and comparative analysis were used. The research carried out in the article shows that the decommissioning of hard coal mines in the examined cities of the Upper Silesian Coal Basin had a negative impact on the balance of local budgets and the level of long-term debt. This was especially true in the cities where all the mines had been decommissioned and which had no way of replacing the mining industry with other economic alternatives. The cities with more diversified economic activity and sources of income were in a better economic condition.

Energy crop as an environmentally sustainable reclamation option for post-mining sites: a life cycle assessment of cassava planting in Vietnam

Using post-mining areas for planting energy crops has emerged as a promising and sustainable reclamation solution due to its potential contributions to environmental protection, land restoration, and especially energy security. However, to ensure the sustainability of this reclamation solution, its environmental performance needs to be thoroughly assessed case by case. Located in Ha Thuong Commune, Dai Tu District, Thai Nguyen Province in northern Vietnam, Nui Phao is the world's largest tungsten mine. To restore post-mining sites at Nui Phao, cassava planting for ethanol production was one of the proposed measures. To support the decision-making, this study employs life cycle assessment to thoroughly evaluate the environmental performance and potential environmental benefits/costs of cassava-based reclamation system in terms of resource consumption and green house gas (GHG) emission. The results show that cassava-based reclamation might bring significant environmental benefits in terms of fossil fuel saving and GHGs reduction (i.e., reduce 50% fossil fuel consumption and 36% GHGs emission); however, it does not bring any benefit in terms of water and land resource consumption. Moreover, the results define cassava cultivation as the "hot spot" of the system, where innovations to enhance the yield and reduce water and fertilizer consumption are required to improve the environmental performance of the cassava-based reclamation system.

Environmental Impacts Related to Closed Mines in Inner Mongolia

Mining activities, while promoting social and economic development, alter the environments and ecosystems of mining areas. Some of the alterations have negative impacts on the environment, while some have positive impacts. By understanding the positive and negative impacts related to closed mines in Inner Mongolia, this research aims to seek advantages of the positive impacts on the environment and reduce the harm of the negative impacts, extending the mining value chain. The paper reviewed four main negative environmental impacts (NEIs) of closed mines and proposed four positive environmental impacts (PEIs) which include ecosystem services, cultural services, land resources and underground space resources, and energy sources and mineral resources. The paper focused on the environmental problems and the PEI utilization of closed mines in Inner Mongolia with 20 representative cases. It carefully studied the Minda Mine which is a good example to combine several PEI utilization objectives. Multiple PEI objectives, as well as the correlations among different objectives, can benefit closed mines ecologically, economically, and socially. In addition, a three-step framework for closed mine revitalization and the factors affecting the compound PEI objectives are mentioned in the paper.

Socio-environmental conflict over abandoned mining waste in Copaquilla, Chile

The material discarded by past mining extractive activities is exposed to the action of different environmental agents and constitutes the beginning of a problem that, inevitably, involves the population and the conditions of the environment where it is deposited. Bearing this in mind, a study of the Copaquilla-Chile valley was carried out with a focus on the socio-environmental conflict produced by the accumulation of abandoned mining waste in its vicinity. The objectives were to identify the role of the different actors and the main causes that originated the conflict and to characterize the physical-natural factors that conditioned the susceptibility and physical vulnerability of the studied environment. The methodological approach combined a set of qualitative and quantitative techniques, using participatory action research techniques (PAR) and multi-criteria evaluation models (MCE) through a geographic information system (GIS). The evaluation of the study area revealed quite severe levels in terms of the indices of susceptibility to processes of mass removal and vulnerability of the aquifer, which led us to infer that the morpho-climatic and hydrogeological characteristics of the sector generated the appropriate conditions to produce large damage to the complex socio-ecological system of the Copaquilla territory. This study generated participatory material, a chronology of the conflict, a database of the physical environment of the Copaquilla valley interpreted in thematic cartographies, and physicochemical soil and water samples to monitor contamination levels.

Identifying industry practice, barriers, and opportunities for mine rehabilitation completion criteria in western Australia

Around the world, the development of acceptable and achievable completion criteria is a necessary part of mine closure planning and fundamental to the successful transition of mined land to a post-mining use. Without adequate completion criteria, a mining company cannot proceed to the process of relinquishment, which is the ultimate goal of most mine closure processes. Despite the central role of completion criteria, there is still a need to build capacity and understanding of how to set targets and develop measurable completion criteria that are accepted by all stakeholders involved. We investigate how completion criteria are currently developed in one of Australia's major mining jurisdictions: Western Australia. Through an industry consultation process that involved interviews and a survey with a total of 102 participants from mining companies, consulting businesses, and relevant regulators, we highlight key challenges and opportunities that the sector faces to successfully define clear, achievable, and agreed completion criteria. This is one of the few industry-wide investigations to capture and analyze the perspectives of stakeholders involved in writing and assessing mine closure completion criteria. Results show that some major challenges included inconsistent coordination within and between stakeholder groups, a lack of knowledge or data about restoration, and an overreliance on status quo practices and post-mining land uses. Our work shows that ongoing research on ecological restoration and technological innovations is necessary, but that additional organizational and regulatory barriers need to be addressed to achieve a consistent, coordinated, multi-stakeholder approach to define completion criteria and to advance successful mine rehabilitation and relinquishment.

Sustainable Social and Environmental Evaluation of Post-Industrial Facilities in a Closed Loop Perspective in Coal-Mining Areas in Poland

The article discusses issues related to the circular economy ideas applied to post-industrial facilities and infrastructure in Polish coal-mining areas. The aim of the article is to indicate directions for sustainability-oriented actions on reusing the remnants of closed mining plants and reshaping the areas which will be transformed under the just transition principles. For this purpose, the article reviews the terminology related to inventories of such facilities and their classification, and also indicates some locations of such facilities. The authors discuss the problem of legal regulations related to the process of closing a mining plant in Poland and also to EU guidelines on the allocation of financial resources from the Just Transition Fund (addressing the EU coal industry, climate change and the potential for clean energy solutions). This research aims at reviewing current research on the above aspects and at raising the problem of managing post-industrial facilities in light of their discontinued function due to mine closure. The article offers a preliminary diagnosis of the scale of research required to investigate the above problems in the view of the expected coal-exit in the Polish economy.

Sustainable Rehabilitation of Surface Coal Mining Areas: The Case of Greek Lignite Mines

Surface lignite mines of the Balkan Peninsula face growing pressure due to the CO2 emissions reduction initiatives, rapidly increasing renewable-power capacity, and cheap natural gas. In this frame, the development of a modern mine land rehabilitation strategy is considered as a prerequisite for mitigating the social and economic impacts for the local communities. In the case of western Macedonia lignite mines, these prospects are investigated based on a PEST (political, economic, social, technological) analysis of seven alternative land uses. Urban (industrial) development, green houses, and industrial heritage parks are considered as the most appropriate land uses for mitigating the socioeconomic impacts due to the loss of employments. For the land uses occupying large areas (i.e., agriculture, forestry, livestock farming, and photovoltaic parks), an optimisation algorithm is proposed for determining the mix of land uses that maximise revenue, equity, and natural conservation and minimise investment. The algorithm was applied using the opinions of 10 experts, who were involved in mine land reclamation projects carried out in the western Macedonia region in the recent past. According to the results obtained, photovoltaic parks are rated as a more attractive investment than extensive agriculture, as regards the anticipation of revenues, while livestock farming and forests are necessary to safeguard the ecosystem’s functions.

Environmental Transformations in the Area of the Kuźnica Warężyńska Sand Mine, Southern Poland

On the basis of the analysis and interpretation of maps, published literature, and environmental reconnaissance, this article discusses environmental transformations in the area of the Kuźnica Warężyńska sand mine in southern Poland over the years 1944–2015. A comprehensive ecological analysis was carried out concerning spatial development, mining activity, hydrogeological and hydrological conditions as well as the biotic environment. Among the unfavourable changes found were a drastic reduction in the agricultural function of the area (from 7.03 to 0.47 km2), mainly due to periodic activity of sand mine in 1967–2002, covering an area of about 5.80 km2, the destruction of the original biocenoses, the depletion and deterioration in quality of the groundwater resources, and man-made transformations of the hydrographic network (during the mine’s activity its length reached over 103 km). Vegetation changes during the 70-year period examined were closely related to human mining activity. The greatest changes occurred at the end of the 1960s when large areas of pine forest were cut down. The analysis of vegetation in the former workings demonstrated that the diversity of habitats within the workings results in a significant increase in species (367 plant species, 2002 birds) and community diversity (Molinion caeruleae, Molinion caeruleae, three Natura habitats) there compared to the adjacent areas. On the other hand, favourable changes included the construction of a flood control reservoir, with an area of 560 ha and a volume of 51 million m3, created in 2003–2005, making the area more attractive for tourism and recreation, and an increase in biodiversity, including the establishment of a Natura 2000 site.

Metal Content of Stream Sediments as a Tool to Assess Remediation in an Area Recovering from Historic Mining Contamination

Lead and zinc mining was booming in the early 1900s in and near Joplin, Missouri; a town within the Tri-State Mining District, USA. After the ore became depleted, mining companies moved out, leaving a profoundly disturbed land. Presently, over 90% of the land has been remediated. We collected sediment samples along two creeks flowing through the historically contaminated area that have been identified as major contributors of metals to downstream reservoirs, Center Creek (14 samples) and Turkey Creek (30 samples). Sediment metal content was determined by aqua regia extraction, the potentially bioavailable fraction by 0.11 M acetic acid extraction, and toxicity by ΣPEC-QCd,Pb,Zn. Zinc and lead content in sediments were high in both creeks notwithstanding remediation actions; e.g., median concentrations of 521 mg/kg Pb and 5425 mg/kg Zn in Center Creek, corresponding to 19 and 52 times the background concentration. The metals’ distribution followed no discernible pattern downstream. The potentially bioavailable fraction varied between 0.36% (Pb, Center Creek) and 4.96% (Zn, Turkey Creek). High toxicity was found in 40% of the samples in Turkey Creek and 78.5% of the samples in Center Creek. While this level of toxicity would likely affect aquatic organisms, its limited mobility under alkaline conditions suggests a lesser threat to humans. On the other hand, this high toxicity will likely persist in sediments for at least a few decades, based on their high metal content and low mobility.

Evaluating the Effect of the Ecological Restoration of Quarry Slopes in Caidian District, Wuhan City

Many measures have been applied to quarry slopes for ecological restoration; however, the performance of these measures has not been clearly evaluated. Thus, research evaluating the effects of the ecological restoration of quarry slopes in Caidian District was carried out to quantify the performance of different ecological restoration methods, to evaluate the effect of ecological restoration projects and to learn the applicability of different restoration technologies in Caidian District. The research can provide a reference for scientific decision-making in the follow-up management of ecological environments in Caidian District. First, the ecological restoration process of quarries in Caidian District was described in detail by visiting the relevant design and construction units. Through observational analysis from the aspects of applicable slope gradient, slope flatness requirements, project cost, the vegetation coverage conditions, the species diversity conditions and construction difficulty, the advantages and disadvantages, as well as the applicability of different ecological restoration technologies were preliminarily clarified. Then, the comprehensive evaluation index system of the ecological restoration effects was established by using the fuzzy AHP method. The ecological restoration effects of each sample plot were evaluated quantitatively based on the data of the evaluation indexes obtained by the field investigation and sampling analysis. Finally, according to the evaluation results, the existing problems in the follow-up management of the ecological restoration of quarry slopes in Caidian District were analyzed, and corresponding countermeasures and suggestions were proposed. The results showed that the quantitative evaluation results obtained by the comprehensive evaluation system of ecological restoration were consistent with the observational analysis results, and the validity of the evaluation system was proven.

People and Post-Mining Environments: PPGIS Mapping of Landscape Values, Knowledge Needs, and Future Perspectives in Northern Finland

Mining can have a notable environmental and social footprint both during the production phase and after the mine closure. We examined local stakeholders’ viewpoints on two post-mining areas in northern Finland, Hannukainen and Rautuvaara, using a public participation geographic information system (PPGIS) approach. Spatially explicit data on local residents’ and visitors’ values, knowledge needs, and future perspectives on mining landscapes were collected with an online map-based survey tool (Harava). The results show that post-mining sites were generally considered unpleasant places. A majority of respondents were of the opinion that areas would need better reclamation and landscaping measures. The landscape surrounding the post-mining sites contained a wide diversity of pleasant places with high nature and recreational value. Respondents addressed various environmental concerns related to the impacts of former mining activities on the quality of ground water and surface water, potential soil contamination, and the safety of natural products. Opinions on the planned mine reopening were strongly divided among the respondents. One of the key questions was whether a large open-pit mine and nature-based tourism can coexist in the same region. Our results highlight that “the shadow of the mine”—observed environmental impacts, uncertainties related to the spatial extent, duration, and magnitude of impacts, and knowledge gaps—can affect local stakeholders’ land use far outside the mining sites and long after the mine closure. Identifying and mapping stakeholder values, opinions, and knowledge needs could significantly improve post-mining land use planning and mitigate the loss of multifunctional landscapes.