Mine Closure Research Articles

Geotechnical Issues in Decommissioning Surface Lignite Mines—The Case of Amyntaion Mine in Greece

Recent changes in the fossil-fuel energy sector require coal mining industries to plan for the future, including developing procedures for decommissioning and closure associated with mines. In surface coal mining, the geotechnical issues of decommissioning include the long-term stability of the pit slopes, particularly as the pit is gradually filled with water. This paper investigates such slope stability issues, with emphasis on the conditions prevailing in the Amyntaion surface lignite mine, in Western Macedonia, Greece. Analytical and numerical methods have been developed and used to estimate the temporal evolution of the overall safety factor, as the water level in the pit rises, creating a lake. It is shown that until the water level in the lake reaches a critical depth of approximately 15–35% of the final equilibrium condition, the safety factor against the overall slope instability decreases slightly (by about 3% in the case study, and up to 5–10% in other conditions) compared to its value at the end of exploitation. At higher lake levels, the safety factor increases significantly, as the beneficial effect of the lake water pressure acting on the slope overcomes the adverse effect of pore water pressure rise inside the slope. In typical mines, the critical water depth is achieved within a few years, since the surface area of the pit is smaller at deeper levels; thus, more favorable slope stability conditions are usually reinstated a few years after mine closure, while the small reduction in safety during the initial stages after closure is inconsequential. The paper investigates the parameters influencing the magnitude of the small reduction in the short-term safety factor and produces normalized graphs of the evolution of the safety factor as the lake water level rises. The results of the analyses can be used in preliminary closure studies of surface coal mines.

Radon Concentrations in Dwellings in the Mining Area-Are There Observed Effects of the Coal Mine Closure?

The article presents the results of radon research, carried out in the area of the mining commune in the Upper Silesian Coal Basin (USCB), Poland. Past investigations in the 1990s on radon concentrations in buildings, located within the mining area, showed that the indoor radon concentrations measured in the area affected by mining were higher than in buildings located outside that area. Currently, all underground hard coal mines within the boundaries of the observed commune have been closed. In 2020, after the closure of the last active mine, radon measurements were started again. The current results of indoor radon concentrations were compared with the archival results from the 1990s. It was found that the radon concentration increased significantly in the basements of buildings where measurements were made in 1990, 2020, and 2021: the maximum values were 260 Bq/m3, 644 Bq/m3, and 1041 Bq/m3, respectively. Therefore, these questions were posed: Do the mine closure processes increase radon migration? How long is the period of the occurrence of changes in radon concentrations in buildings after the cessation of mining operations?

Conceptual framework to assist in the decision-making process when planning for post-mining land-uses

To avoid a climate crisis, major industrial economies are being urged to reduce their dependence on coal-fired power generation. Given decarbonisation pressures, many coal mining regions worldwide are facing the prospect of mine closures. However, few viable planning mechanisms are available to assess potential post-mining alternatives and enhance regional transition. To optimise transition outcomes and maximise stakeholder acceptance, mechanisms that incorporate input from a diverse range of stakeholders and disciplinary perspectives are needed at a regional scale. These mechanisms need to compute seemingly disparate types of multi-disciplinary and multi-scale data in a robust, coherent, and transparent fashion. This paper presents a conceptual mixed-method framework for post-mining land-use planning that integrates stakeholders’ involvement, GIS, multi-criteria decision-making and fuzzy logic. The framework utilise environmental and socio-technical data to support the decision-making process. This work is driven by the urgency to offer mining regions in transition a tool for planning their post-mining future. The proposed framework builds on previous literature and has the ability to support a wide variety of institutions and professionals in their efforts to facilitate the post-mining planning process in mining-dependent regions toward a low-carbon future.

Assessment of the potential use of construction and demolition waste as a component for the recovery of areas degraded by mining

The evolution of modern civilization brings with it a series of challenges regarding the management of its waste. Proper disposal of construction and demolition waste (CDW) has become a challenge across the planet. Parallel to this challenge, there is another, that of recovering areas degraded by mining. The objective of the present work was to characterize through X-ray fluorescence (XRF), and X-ray diffraction (XRD) samples of CDW collected during the period from October 2018 to October 2019 in a recycling plant and to determine its potential as an element in the production of soils in the recovery of areas degraded by mining. Calcite and quartz were found in the CDW samples, as well as trace elements such as Fe, Mg, Mn, Cu, Zn, Ni, essential elements for plant nutrition, capable of restoring the chemical and physical conditions of soils. The results obtained showed that Chromium (Cr) and Barium (Ba) elements were found above the limits of CONAMA Resolution 420/2009 (Brazil). A comparison was made with Orden AAA/661/2013 (Spain), which guides the disposal of CDW in mining areas as a form of final disposal and mine closure. The presence of heavy metals is considered normal in Brazilian soils, some being considered essential micronutrients. The results provide data to affirm that the CDWs can be used in soil production to recover areas degraded by mining, through the application of tests on a larger scale and with a soil-water-plant interface.

Study on restoring abandoned mine lands to economically usable state using the post‐occupancy evaluation method

AbstractAbandoned mine lands are a common element of the contemporary landscape. In administrative practice, they are rated low, yet they are of interest to informal users and scientific and cultural communities. The aim of our research was to identify the possibilities of using qualitative research methods, applied in architecture, to create friendly, urban spaces with a universal character in the areas of abandoned quarries. The study was conducted in the Sadowa Góra quarry area in southern Poland, using the post occupancy evaluation (POE) method. The results of the conducted analysis confirm the effectiveness of the POE method in restoring abandoned mine lands to an economically usable state by surveying users' opinions on accessibility, functionality, and visual quality. The applied methodology was used as effective support for the transformation process of post‐mining areas and as a tool to optimize the costs of their reclamation and maintenance.

A comprehensive model for socially responsible rehabilitation of mining sites using Q-rung orthopair fuzzy sets and combinative distance-based assessment

Mining companies play a critical role in developing mineral wealth across the globe. Interacting effectively with local communities is yet another potential source of long-term profitability, because of the opportunities that are not accessible if community engagement is not achieved. The financial advantages of a positive company image can be linked to attracting and retaining employees, as well as sustaining or even enhancing the capacity to do business with local suppliers. The socially responsible rehabilitation of a site after mine closure can facilitate access to new or former jobs for the mine workers. This study focuses on how to identify the best rehabilitation strategy after the closure of a mining site. In particular, a q-rung orthopair fuzzy sets (q-ROFSs) based CODAS (COmbinative Distance-based ASsessment) model is developed to support the evaluation of socially responsible rehabilitation activities in mining sites. To test and validate the model, the proposed methodology is compared to the ARAS (Additive Ratio Assessment) method. The results show that rehabilitation and social transition subsidy is the best alternative among those considered. Implementation of this alternative benefits the mining companies and also brings social benefits to the mine workers and the wider communities within the mining site.

Inter-regional coal mine competition in the US: Evidence from rail restrictions

This analysis looks at how Appalachian coal mining responds to restrictions in coal production from the Western US. An unexpected reduction in the ability to move coal from the Powder River Basin (PRB) in 2005–06 led to a reduction in the rate of Appalachian coal mine closure, no impact on the rate of coal mine openings, and an increase in the number of employees in Appalachian coal mines. On the demand side, plants in the Midwest are more likely to switch from PRB coal to Appalachian coal, using the spot market to procure this coal, which is costlier and of lower quality. The results imply inter-regional coal mine substitution possibilities and shed light on the tradeoffs inherent in policies that impact production in one region.

Political economy of just transition: Disparate impact of coal mine closure on state-owned and private coal workers in Inner Mongolia, China

This paper adopts a political economy perspective to examines the transition management of China's coal mine closure policy and explores how and to what extent a just transition has been achieved. Drawing on first-hand evidence collected from a coal city in Inner Mongolia, China, we found that while the coal workers from state-owned mines were supported by job reallocation and retirement plans, the coal workers from privately owned mines, who were mostly of rural origin and hold a rural hukou, were laid-off without adequate compensation and job assistance. Furthermore, the government failed to help the private coal workers, as the predicament of the private coal workers was not considered the responsibility of the government. These issues were fundamentally linked to China's political economic contexts such as rural-urban inequality, incomplete marketization, and authoritarianism. In addition to demonstrating the importance of understanding just transition through a political economy perspective that is sensitive to local contexts, the findings also warn against treating workers from the fossil fuel industry as a homogenized whole because it may mask the reality of structural inequality, obscure the differences among workers, and create a false appearance of justice by excluding certain groups from the logic of a just transition for all. We argue that the transition cannot be considered as “just” without identifying who is the most vulnerable group affected by such a transition. Therefore, “just transition for whom” is a key question in the evaluation of transition management.

The Effects of Surface Lignite Mines Closure on the Particulates Concentrations in the Vicinity of Large-Scale Extraction Activities

The European green deal and energy transition policies and the competition primarily shaped by the high price of carbon dioxide emission allowances and the consistently reduced cost of renewable energy technologies directly affect the coal and lignite extraction industry. Lignite production in Western Macedonia Lignite Centre reduced from 43.2 million tons in 2010 to 10.3 million tons in 2020. This development affects the ambient air quality of the large lignite mine area, as evidenced by the records of 10 monitoring stations incorporating the laser light scattering method. All stations measure reduced particulate matter (PM10 and PM2.5) concentrations compared to the period before 2010, while the number of annual exceedances of the limit value for the daily average PM10 concentrations has been decreased. Moreover, differences in air quality measurements of monitoring stations related to their distance from mining activities now tend to be minimized. Based on these facts, it can be predicted that, after the closure of lignite extraction and the electricity generation activities, the concentration of particulates in the atmosphere will reach the typical levels for rural areas of Southern Europe, no matter what the mines’ land reforestation and repurposing program will include.

Improving the policy framework for financial assurance for mine closure in Mongolia

Mongolia is rich in mineral resources. Its economy is based on mining. As of 2020, mineral licenses for 1.65 million hectares have been issued in Mongolia, which represent 1% of the country's territory. Mining involves a great negative impact on the environment and society in mining areas not only during mining operations but also after mines are closed. To avoid such impacts on the environment and local communities, it is imperative to secure funds for appropriate mine closure. Therefore, adequate policy and regulatory frameworks for mine closure, including financial assurance for mine closure, are key to ensuring proper mine closure and minimizing negative environmental, health and safety impacts that may result from inadequate mine closure or abandoned mines. Our comparative study on financial assurance for mine closure, based on the internationally-applied guidelines, show that Mongolia's current legal framework regulating mining activities includes only a minimum level of requirements for mine closure and thus represents a policy and regulatory weakness that may lead to inadequate mine closure, or abandoning mines without proper closure.The study applies one of the typical formulas to calculate the cost of a recent mine closure in Mongolia. We then expand such calculations to cover the entire nation for mines in explorations or in operations that will be closed in the near future. Based on this estimation, we find that the total funds required to rehabilitate the existing areas affected by mining represent from 0.07 to 51.1% of local government budgets. If financial assurance for mine closure is not secured in order to avoid the abandonment of mines, financial burdens for mine closure in the future will place a heavy burden on central and local government budgets and the country's economy, along with serious negative impacts on the environment, biodiversity and human health.

Groundwater quality and its potential health impacts nearby inactive mines using PIG and geospatial technology, Southwestern part of Cuddapah basin, Andhra Pradesh, South India

The primary intend of this research is to determine the standard drinking water quality build upon on the Pollution Index of Groundwater (PIG) and health risk index. For this, fifty groundwater samples were chosen and determined for chief cations & anions in the Southwestern part of Cuddapah basin (SW). Maximum samples are under the allowable level of W.H.O standards except Fluoride and nitrate concentrations. Around 60% and 62.5% of the groundwater surpass the allowable range (1.5 mg/L) of fluoride and nitrate (45 mg/L), respectively. As a result, groundwater is not potable due to fluoride and nitrate levels, and a health risk assessment was conducted in this area. From the PIG values; 80% of the samples fall under insignificant pollution category. Nitrate Pollution Index value shows that; 88% of the groundwater polluted with high nitrate content as per national guide lines for drinking purpose. As per USEPA guidelines non carcinogenic effect of nitrate and fluoride in this region vary from 0.01 to 14.48 (adults), 0.02–14.68 (children), 0.01–11.8 (infants), while 92.5, 92.5%, 80% of groundwater is surpass the recommended value (>1) of THI for adults, children and infants. Higher fluoride concentration may be due to geogenic and higher levels of nitrate concentration may be due to human induced activities including fertilizers, industrial effluent and service pipe leakage. The predominant geochemical processes in this region are weathering, ion exchange and to reduce fluoride and nitrate-contaminated in water intake in the research area, precautions should be adopted.

Mine closure, social disruption, and crime in South Africa

AbstractThe international literature links mining booms with social disruption. The rapid economic and population growth that mining brings increases urban crime and social problems. But insufficient attention has been paid to the reverse situation: the social disruption that can accompany the closure of a mine. We compare crime statistics for four categories of small city, known in South Africa as “intermediate city municipalities,” from 2009 to 2018. Contrary to the findings of international studies, we find that those where mining was in decline had some of the highest crime rates, particularly in the category of sexual offences, whereas those where mining was growing had the lowest. Our research shows that mine decline and closure can contribute to social disruption. We argue that South African government policy has exacerbated this problem in the context of mine decline and that several dependencies created by mining further contribute to the problem. We challenge the assumption that fast population growth and an increase in the male population are prerequisites for social disruption. Our paper suggests the need for modifications to social disruption theory.

Next generation restoration metrics: Using soil eDNA bacterial community data to measure trajectories towards rehabilitation targets

In post-mining rehabilitation, successful mine closure planning requires specific, measurable, achievable, relevant and time-bound (SMART) completion criteria, such as returning ecological communities to match a target level of similarity to reference sites. Soil microbiota are fundamentally linked to the restoration of degraded ecosystems, helping to underpin ecological functions and plant communities. High-throughput sequencing of soil eDNA to characterise these communities offers promise to help monitor and predict ecological progress towards reference states. Here we demonstrate a novel methodology for monitoring and evaluating ecological restoration using three long-term (>25 year) case study post-mining rehabilitation soil eDNA-based bacterial community datasets. Specifically, we developed rehabilitation trajectory assessments based on similarity to reference data from restoration chronosequence datasets. Recognising that numerous alternative options for microbiota data processing have potential to influence these assessments, we comprehensively examined the influence of standard versus compositional data analyses, different ecological distance measures, sequence grouping approaches, eliminating rare taxa, and the potential for excessive spatial autocorrelation to impact on results. Our approach reduces the complexity of information that often overwhelms ecologically-relevant patterns in microbiota studies, and enables prediction of recovery time, with explicit inclusion of uncertainty in assessments. We offer a step change in the development of quantitative microbiota-based SMART metrics for measuring rehabilitation success. Our approach may also have wider applications where restorative processes facilitate the shift of microbiota towards reference states.

Serbołużyckie Stronnictwo Narodowe / Łużycki Alians jako partia narodu i regionu

Sorbian National Party / Lusatian Alliance as a National Minority and Regional PartyLusatian Sorbs are the smallest Slavic ethnic group. They live in Lusatia, which is part of the German states of Saxony and Brandenburg. The Lusatian Sorbs engage in political activities at the local, regional, state and national levels. In 2005, the Sorbian National Party (in the Lower Sorbian language: Serbska ludowa strona, SLS) was founded, and in 2010 its name was changed to the Lusatian Alliance (Łužyska alianca, ŁA). The Party’s leader is Hannes Kell. The organisation is both a national minority and a regional party. The Party’s programme includes the introduction of equal status of both German and Lusatian languages within the Sorbian territory, promotion of the Lusatian language in Lusatia, obtaining political autonomy for Lusatian Sorbs, as well as striving for the reduction and eventual closure of open pit lignite mining, which causes damage to the environment and destroys the region’s villages. The Lusatian Alliance desires to hold a democratic election and appoint Sorbian authorities that would have a budget at their disposal to financially manage and oversee Sorbian education.

Dynamic elution of residual ammonium leaching agent from weathered crust elution-deposited rare earth tailings by magnesium chloride

The release of residual ammonium (RA) leaching agent from weathered crust elution-deposited rare earth tailings would cause serious environmental pollution, and it was necessary to efficiently remove it from the ore body before the mine closure. In this study, occurrence states of the RA were determined and dynamic elution of RA from rare earth tailings by using magnesium chloride as eluent was investigated. Effects of initial concentration, pH, flow rate, and particle size on the ammonium removal efficiency were investigated, and variations of ammonium occurrence states before and after elution were determined. Lastly, elution mechanism was discussed. Results showed that removal efficiency of RA by magnesium chloride was significantly higher than that by deionized water, and elution efficiency of RA could reach about 95.7% at the optimum laboratory experiment conditions. Energy dispersive spectrometer (EDS) analysis illustrated that the residual ammonium was replaced by Mg2+ during the elution process, and occurrence state experimental results showed that 94.0% of water-soluble and adsorbable ammonium was eluted. The empirical kinetic equation of eluting RA by magnesium chloride was established as 1–2/3α-(1-α)2/3= 0.02*C00.6t. This study provided a valuable method for reducing environmental pollution caused by the release of the residual ammonium from the rare earth tailings.

Collection Tubes Can Cause False Elevations in Occupational and Clinical Evaluation of Antimony Exposure.

Occupational exposure to antimony has become rare in the past decades due to antimony mine closures and technological improvement in antimony processing plants in the USA. Although antimony's ubiquitous presence in plasticwares does not pose known health risk, it can present as a potential contaminant to antimony analysis for occupational exposure assessment. To understand the level of antimony contamination from plastic collection devices, we evaluated two different whole-blood plastic collection tubes that are routinely used for trace and toxic element assessment: royal blue BD Vacutainer® EDTA tube and Greiner VACUETTE® trace elements sodium heparin tube. We analyzed how different fill volumes may impact the concentrations of antimony detected. Although both collection tubes can introduce antimony contaminations to nitric acid and neutral buffer rinse, the Greiner heparin tube introduces a significantly lower amount of antimony to freshly collected whole-blood samples compared to the BD EDTA tube. When patients' samples are collected with BD EDTA tubes, they would exhibit elevated antimony concentrations that can be interpreted as potential antimony exposure. We conclude that the royal blue BD EDTA plastic tube is not suitable to evaluate blood antimony levels, and laboratories need to validate their own alternative sources when the glass tubes are not available.

Facilitating Open Pit Mine Closure with Managed Aquifer Recharge.

Dewatering of open pit mines can lower the regional water table for distances of several kilometers from the pit. When the mine is closed, dewatering operations usually cease, and the water table near the pit begins to rise. If the pit is backfilled, the water table will eventually recover, but this recovery may take several hundred years. However, if the extracted water is re-injected into the subsurface, then this may accelerate recovery of the water table. We show that there is an optimal distance for re-injection, which is sufficiently far from the mine to minimize the amount of groundwater that flows back to the pit during mine operations (and hence necessitate additional pumping) but is still close enough to speed up the water table recovery post-mine closure. The optimal injection distance increases with the aquifer hydraulic diffusivity and the mine life (duration of dewatering and injection), and typically ranges between about two and nine times the radius of the mine pit. Where the mine pit is not backfilled, the relative reduction in drawdown due to injecting all the pumped water at the optimal distance is between approximately 10% and 50% after a recovery time equal to the mining period, increasing to 30% to 90% after a recovery time five times the mining period. The relative drawdown reduction due to managed aquifer recharge will be even greater for a pit which is backfilled when mining ceases.

Time-Varying Surface Deformation Retrieval and Prediction in Closed Mines through Integration of SBAS InSAR Measurements and LSTM Algorithm

After a coal mine is closed, the coal rock mass could undergo weathering deterioration and strength reduction due to factors such as stress and groundwater, which in turn changes the stress and bearing capacity of the fractured rock mass in the abandoned goaf, leading to secondary or multiple surface deformations in the goaf. Currently, the spatiotemporal evolution pattern of the surface deformation of closed mines remains unclear, and there is no integrated monitoring and prediction model for closed mines. Therefore, this study proposed to construct an integrated monitoring and prediction model for closed mines using small baseline subset (SBAS) interferometric synthetic aperture radar (InSAR) and a deep learning-based long short-term memory (LSTM) neural network algorithm to achieve evolution pattern and dynamic prediction of spatiotemporal surface deformation of closed mines. Taking a closed mine in the western part of Xuzhou, China, as an example, based on Sentinel-1A SAR data between 21 December 2015, and 11 January 2021, SBAS InSAR technology was used to obtain the spatiotemporal evolution pattern of the surface during the 5 years after mine closure. The results showed that the ground surface subsided in the early stage of mine closure and then uplifted. In 5 years, the maximum subsidence rate in the study area is −43 mm/a, and the cumulative maximum subsidence is 310 mm; the maximum uplift rate is 29 mm/a, and the cumulative maximum uplift is 135 mm. Moreover, the maximum tilt and curvature are 3.5 mm/m and 0.19 mm/m2, respectively, which are beyond the safety thresholds of buildings; thus, continuous monitoring is necessary. Based on the evolution pattern of surface deformation, the surface deformation prediction model was proposed by integrating SBAS InSAR and an LSTM neural network. The experiment results showed that the LSTM neural network can accurately predict the deformation trend, with a maximum root mean square error (RMSE) of 5.1 mm. Finally, the relationship between the residual surface deformation and time after mine closure was analyzed, and the mechanisms of surface subsidence and uplift were discussed, which provide a theoretical reference for better understanding the surface deformation process of closed mines and the prevention of surface deformation.

Role of the Tree Species Selected in Developing Swampy Forest System for Passive Treatment of Acid Mine Drainage

Coal mining is one of economic sector that requires forestry area in Indonesia. Most of coal mining concession are forestry area loan use from the government and during mining operation facing with acid mine drainage (AMD). AMD passive treatment can be integrated with revegetation process that related with better handling of overburden (OB) with potential acid forming (PAF) during reclamation processed. The most expensive methods and uncertainty process are the use of quick lime in treatment of AMD. During operation and preparing mine closure stage need to create the effective one to comply with the regulation. “Swampy Forest (SF) system” is an alternative method of sustainable and naturally process. Selecting the appropriate tree species as a preliminary process to develop a better SF system by batch experiment in the form of a forest constructed wetland. The tree species selected are Nauclea orientalis (lonkida tree) and Melaleuca cajuputi (kayuputih tree) as non-local species then Nauclea subdita (bangkal tree) and Melaleuca leucadendron (galam tree) as local species have been selected. Local species higher in Fe and Mn adsorption in pH of AMD <4 then nonlocal species higher in Fe and Mn adsorption on pH of AMD >4 condition.

CURRENT STATE OF COAL MINING ENTERPRISES AND THEIR PROSPECTS

Ukraine has 10% of proven coal reserves in Europe and 3% of the world. Delays in the reform of the coal industry are reducing the profitability of coal mining companies. Despite this, experts warn against ill-considered closure of coal mines.
 Generalization and analysis of the material on the current state and closure of Donbass mines, preliminary own research and field work in Donetsk-Makeyevka and Krasnoarmeysk coal districts were carried out.
 The proposed recommendations for the transformation of individual coal mining companies should start now, using grants from European countries. At the same time, it is necessary to take into account scientifically sound climatic, geological, environmental and economic factors to determine the directions of transformation of each individual mine, taking into account their features.
 It is advisable not to close mines with reserves, but to finance them to become profitable. Coal mining companies located within the city should be converted into parks, science and technology or technology parks, wind and solar EC. It is advisable to start the transformation process before the closure of the coal mining company, which will save jobs and create new ones.