Search Results (33)

In this article, the results of full-scale experiments on the addition of a sodium sulfide to the ${\mathrm{CaCO}}_3$ slurry circuit in a wet flue gas desulfurization (WFGD) plant are presented. Tests are performed on two comparable WFGD installations (spray tower, 4 spraying levels and two stage gypsum de-watering by hydrocyclones and vacuum belt filter) which allows the investigation of the influence of lignite composition (lignite mined in Poland and the Czech Republic are compared) on the reduction in mercury emission. Additionally, the efficiency of precipitation of metals from the slurry (Hg, Zn, Pb, Cd, Cr, Cu, Ni, Fe, Se, and Mn) is investigated as the result of sulfide addition. For both objects, mercury re-emission from absorber occurs (the concentration of mercury in the chimney is higher than that before the WFGD absorber) and the sulfide addition to WFGD slurry stops this phenomenon. The addition of sulfide works effectively (mercury removal efficiency from flue gas reaches up to 88% for Polish tests and up to 87% for Czech Republic tests). For the tests in the Poland power plant, all of measured metals are precipitated from the slurry (precipitation of metals efficiency varied from 2% for zinc to 88% for mercury), but in the case of the test in the power plant in the Czech Republic, there is no effect on manganese, iron, and lead (precipitation of metals efficiency varied from 6.5% for copper to 86% for mercury). The addition of sulfide works effectively for lignite mined in Polish and Czech power plants under the conditions of similar WFGD installations. Full article

The rehabilitation of post-mining sites is crucial due to the severe environmental impacts of mining, including land degradation, heavy metal pollution, and loss of biodiversity. Effective reclamation strategies are essential to reverse these impacts and enable sustainable land use. This study presents the possibility of the rehabilitation of a post-mining area in Velenje, Slovenia, using artificial soils made from combustion by-products amended with lignite and organic compost, and explores the potential of lignite mine water for irrigation. This approach introduces an innovative solution that differs from the traditional methods of rehabilitating degraded areas. Physicochemical and phytotoxicity tests were conducted to determine the quality of the soil substitutes. The analysis revealed that the pH, salinity, and chemical composition of soils positively impacted Sinapis alba growth as a test plant, with the most promising compositions containing 20–30% of lignite by weight as a replacement for organic compost. Irrigation water quality parameters, such as electrical conductivity (0.87 dS/m), the sodium absorption ratio (2.09 meq/L), and boron content (0.05 mg/L), indicated a low soil dispersion risk, while the residual sodium carbonate (3.02 meq/L) suggested a medium risk. Although, the concentration of toxic elements did not exceed the threshold limits; the long-term irrigation with mine water requires the monitoring of the molybdenum levels. These results suggest the potential for using artificial soils and mine water in post-mining land reclamation but highlight the need for the monitoring of their quality. Full article

A large contiguous former opencast lignite-mining district is located in Lusatia, Germany, about 100 km south of Berlin. Since this region has been heavily polluted by acid mine drainage from opencast lignite mines, time- and cost-efficient investigation methods are required to obtain comprehensive information on aquifers. In summer 2021, BGR carried out a helicopter-borne electromagnetic (HEM) survey with its helicopter and a RESOLVE system covering an area of about 250 km². While current surface water levels are derived from in-flight altitude measurements, the spatial resistivity distribution shows indications for the water table in the entire survey area. Apparent resistivities agree very well with water resistivities measured in larger lakes, where the distance to the lakeshores outreaches the system’s footprint. While groundwater sampling requires observation wells, we use HEM results to close the gaps between the sparsely distributed wells. The analysis of groundwater samples shows that groundwater EC correlates with dissolved iron (Fe²⁺) and sulfate (SO₄²⁻) content. HEM resistivities help to approximate groundwater EC, and further Fe²⁺ and SO₄²⁻ contents at the observation wells, and to estimate these within the mining area where oxidative pyrite weathering processes dominate other contamination processes. Full article

The European Union prioritizes nature restoration, particularly in semiarid Mediterranean regions where integrating degraded coal mining areas into the landscape is essential. This involves maximizing water use and controlling runoff. A rehabilitation project in a former mining quarry was conducted with the objective of constructing suitable Technosols to support vegetation, limit erosion, and reduce rehabilitation costs. To prepare the substrate, mine spoils (saline materials) were mixed with residual materials, including discarded lignite powder, sewage sludge, pig slurry, and straw. Pig slurry was also introduced as a mulch in the experiment. A complete randomized block design with three replicates was set up, with each block containing two plots of the prepared substrate. In one of the plots, pig slurry was applied on the surface as a mulch to enhance infiltration and promote plant establishment. The quality of the newly created Technosols and the benefits of mulch application were evaluated 2 and 4 years after the rehabilitation. After two years, salt-tolerant plant species colonized the rehabilitated areas, providing sufficient vegetation cover to control water, soil, and nutrient losses, keeping soil losses below a 2.2 Mg ha⁻¹ yr⁻¹ threshold. Four years later, the new Technosols showed a fourfold increase in soluble organic-C content (up to 0.59 g kg⁻¹) and higher soil respiration rates compared to the mine spoils and lignite powder in the surrounding degraded quarry areas. No significant differences were observed in any parameters due to superficial slurry application. Addressing salinity and optimizing vegetation cover are crucial for the successful formation and sustainability of Technosols in these environments. Full article

In the vicinity of the Adamów power plant, which operates in the catchment area of the Kiełbaska river, there is a significant shortage of water resources caused by the intensive use of water by the energy industry and agriculture. The development of the plant by replacing the outdated coal-fired (lignite-fired) units with modern gas and steam units may contribute significantly to reducing the negative impact on the environment and reduce the demand for water resources relative to coal technology. Gas and steam units are a much more energy-efficient technology. This implies a lower demand for water, a reduction in pollutant emissions, and greater operational flexibility, which enables the units to adapt to changing hydrological and environmental conditions. The high efficiency of these units limits the need for frequent water-refilling, while allowing for a more sustainable and stable production of energy. Based on an analysis of hydrological data for the years 2019–2023, it was estimated that water stress is observed in this catchment area on 198 days per year, which accounts for c.a. 54% of the hydrological year. Therefore, it is assumed that inter-catchment pumping stations with a flow of 0.347 m³∙s⁻¹ will be required. This sets the demand for water at 5.95 million m³ per year. The planned water transfer will be carried out from Jeziorsko reservoir on the Warta river through the catchment area of Teleszyna river. Moreover, there are plans for the reconstruction of the layout of Kiełbaska Duża and Teleszyna rivers, which would involve the restoration of natural run-offs, following the discontinuation of open-pit lignite mining. This will additionally be supported by the reduced demand for water in the water use system when using the modernised power plant. The analysed data made it possible to develop hydrological scenarios that take the future reduction in water stress into account by implementing plans to restore the former hydrographic system in the region. These investments would also foresee the creation of new retention reservoirs (in former mining pits) with a capacity of nearly 900 million m³, which will significantly increase the region’s water resources and retention potential, supporting hydrological and energy security for the years to come. Full article

The content of unfrozen water in the freezing process of coal body affects the microscopic pore structure and macroscopic mechanical properties of coal body and determines the permeability-enhancement effect of coal seam and the extraction efficiency of coal mine gas. To investigate the evolution mechanism of unfrozen water content in the melting process of lignite, this paper takes the melting process of lignite liquid nitrogen after freezing for 150 min as the research object and quantifies the spatial change process of unfrozen water distribution based on two-dimensional nuclear magnetic resonance technology. Through the accurate interpretation of the superimposed signals of different fluids, the 2D NMR technique can more easily obtain the spatial distribution of different fluids and even the specific content of fluids in different pores in coals. The results show that at −196 °C, the unfrozen water mainly existed in the small coal pore and the small ice pore in the large pore. As the temperature rose, the pores melted, and free water began to be produced. The mathematical model analysis shows that there was intermolecular potential energy between fluid molecules and the coal pore wall, and the pore wall exerted a part of pressure on its internal fluid, and the pressure affected the melting point of pore ice with pore diameter and melting temperature, resulting in the difference of unfrozen water content. Full article

This paper addresses several important problems and methods related to studies of inland waters based on the existing scientific literature. The use of UAVs in freshwater monitoring is described, including recent contact and non-contact solutions. Due to a decline in biological diversity in many parts of the globe, the main threats are described together with a modern method for algae and cyanobacteria monitoring utilizing chlorophyll a fluorescence. Observed disturbances in the functioning of river biocenoses related to mine waters’ discharge, causing changes in the physico-chemical parameters of waters and sediments, give rise to the need to develop more accurate methods for the assessment of this phenomenon. Important problems occurring in the context of microplastic detection, including the lack of unification, standardization and repeatability of the methods used, were described. In conclusion, accurate results in the monitoring of water quality parameters of inland waters can be achieved by combining modern methods and using non-contact solutions. Full article

Pollution of water sources with heavy metals is a pressing environmental issue. To this end, various procedures are being used to remediate water, including sorption. The aim of this study was to investigate the effectiveness of humic acids (HAs) and fulvic acids (FAs) for the removal of metals from water. Specifically, HA and FA were examined for their potential to be used as sorbent materials for 26 heavy metals, alkali metals, and alkaline earth metals. HA and FA were isolated from lignite samples from two mines (Mavropigi mine and South Field mine, Kozani, West Macedonia, Greece). Experiments were carried out using natural mineral water without pH adjustment, so as to gain a better overview of the sorption efficiency in real-life samples. The results showed that FAs were able to sorb most of the examined metals compared to HAs. Several metals such as Ba (34.22–37.77%), Ca (99.12–99.58%), and Sr (97.89–98.12%) were efficiently sorbed when 900 ppm of FAs from both sources were used but were not sorbed by HAs from any source (≤0.1%). Due to the functional groups on the surface of FA, it is plausible to conclude that it can remove more metals than HA. Meanwhile, lignite from the South Field mine was found to be more efficient for the sorption efficiency in lower concentrations (300–600 ppm), whereas lignite from the Mavropigi mine was more effective in higher concentrations (900 ppm). For instance, higher removal rates were observed in Mo (62.84%), Pb (56.81%), and U (49.22%) when 300 ppm of HAs of South Field mine were used, whilst the employment of 900 ppm of HAs from Mavropigi mine led to high removal rates of As (49.90%), Se (64.47%), and Tl (85.96%). The above results were also reflected in a principal component analysis, which showed the dispersion of the metal parameters near to or far from the HA and FA parameters depending on their sorption capacity. Overall, both HA and FA could be effectively utilized as sorbent materials for metal removal from water samples. The results of the research indicate a potential application to the remediation of water from metals under dynamic conditions in order to protect public health. Full article

Hydrogeological conditions constitute a crucial factor during mining excavations. However, they could also define when and how rapidly the final pit voids will be filled with water after mine closure. They also influence the final steady-state water volume of the lake formed. This paper investigates the hydrogeological conditions of the Kyparissia surface mine in the Megalopolis lignite field. Due to the very rapid filling from three karstic aquifers, these were the determining factors for ceasing exploitation in 2012. A pit lake has been formed in the mine void since 2017, with an average depth of 30 m and a maximum depth of approximately 36 m, extending to a surface of 0.8 km². The significant role of the hydrogeological setting is highlighted in the creation, maintenance, and development of pit lakes. Full article

In the context of the lignite phase-out plan in Greece, the aim of the Public Power Corporation (PPC) is sustainable mine closure and land reclamation and, at the same time, the enhancement of safe mining and post-mining activities. The main objective of this study is to provide a methodology to identify the areas in complex surface mining landscapes that are more vulnerable to flooding using remotely sensed satellite data. This is an integral part of the strategic planning of the new land uses and the design of new and improved water management strategies. In this research, the change detection method is applied using Synthetic Aperture Radar (SAR), and flood-prone zones are delineated. Full article

The energy crisis in Europe and Poland caused by the conflict in Ukraine has renewed the debate in some countries about the wisdom of abandoning the use of local fossil fuels. The rise in gas and oil prices with little change in the cost of extracting lignite from open pit mines has led to a renewed consideration of lignite as the cheapest source of energy. This is not entirely true, as the level of costs at power plants ignores many external costs that are not included in the costs of energy producers, but are borne by the general public or other parties. One such cost is the external costs incurred by agriculture as a result of open pit lignite mining and the associated depression funnels. The Bełchatów lignite open pit is the deepest open pit in Europe and is expected to be in operation by 2038. The aim of the study was to assess the external costs that farmers will incur as a result of further open pit mining of brown call from the Bełchatów deposit, i.e., between 2023 and 2038 as well as in the 16-year extended period of restoration of water relations around the open pit. The decrease in crop yields and animal numbers was estimated in a comparative analysis, which compared changes in the yields of selected plants and animals in the area affected by the open pit to those in neighboring areas that were not affected. The analysis showed that the external costs to be borne by agriculture as a result of the further exploitation of the Bełchatów deposit will amount to an average of EUR 2.90 billion, and, depending on the calculation variant, from EUR 2.51 billion to EUR 3.14 billion. Including this amount in the cost of electricity production would result in an increase of EUR 9.11·MWh⁻¹, which is 18.8% of the average wholesale price of electricity in Poland in 2017–2021. On the one hand, the increased consumption of lignite in electricity production, which is currently observed and may last for several years, may shorten the life of the open pit by up to 2 years. Shortening the mining period by one year, assuming that all the coal in the deposit is mined, will reduce the external costs for agriculture by about EUR 185 million, i.e., EUR 0.58·MWh⁻¹. On the other hand, the increase in European Emissions Trading System (ETS) prices, the decrease in gas prices and the increase in energy production from renewable energy source (RES) will make lignite power generation profitable only during the periods with the highest prices, so that by 2038 lignite will not be mined in its entirety. Every 10 Gg of coal that will not be mined by 2038 will result in an increase in external costs in agriculture per MWh of EUR 0.23·MWh⁻¹. Full article

The sustainable transformation of surface coal mines aims to recover geoenvironmental and socioeconomic factors (ecosystems, landscape, soil, water, employment, etc.) related to extractive operations. The transition to sustainability starts when a mine enters the ageing/closing phase and includes large-scale technical activities for repurposing the mined sites. Moreover, circular economy practices and methods are introduced for efficient and socio-environmentally friendly use of mining wastes and non-exploited resources. The selection of a strategy for the sustainable transformation of a mine constitutes a complex decision-making framework presenting various practical problems. This paper provides a critical analysis concerning the definition of the transformation problems and suggests a decision-making methodology for the selection of a strategy for sustainability with a case study of a closing surface lignite mine in Greece. The methodology combines (a) a strengths–weaknesses–opportunities–threats (SWOT) analysis of the factors of critical importance for the evaluation of alternative strategies, and (b) the analytical hierarchy process (AHP) applied for the quantification and use of these factors for the selection of the most advantageous strategy. In this context, it is based on expert judgement. The results indicate that the proposed analysis can be used as a practical decision-making tool to resolve complex problems related to the mine closure and post-mining issues. Full article

During opencast lignite mining, the natural landscape is damaged, along with soils, and new anthropogenic landforms are created which require reclamation. Usually, the evaluation of the effects of reclamation (mostly forestry) is concerned with changes in chemical properties in the first years, mainly in the surface horizon. This study analyzed the effect of long-term agricultural reclamation (43 years) on the physical and water retention properties of Technosols. The experiment involved cultivation of winter wheat and winter oilseed rape under 3 fertilization variants. After 43 years, an Ap horizon (Ap1 and Ap2) developed in fertilized Technosols, but was not clearly formed in unfertilized minesoil. In Ap1, there was improvement in the physical quality (S), bulk density (BD), particle density (PD), structural stability index (SI), soil porosity (SP), air-filled porosity (AFP), field capacity (FC) and plant available water capacity (PAWC). In Ap2, properties were comparable to those in the surface horizon of unfertilized Technosols and to those observed before reclamation. Regardless of fertilization, there was deterioration in physical quality in parent materials. In general, the properties of fertilized Technosols have improved in the surface horizons, but increasing fertilization above plant requirements does not lead to their further enhancement. Full article

Over a period of 30 years, the surface water level in the north-west of Konin, in the east of the Wielkopolska region, decreased by almost 6 m, resulting in a reduction of the surface area of the majority of nearby lakes, the disappearance of smaller water bodies and wetlands, and the drying out of streams draining the area. The causes of the decrease in the surface and groundwater level in the region are complex. They include both natural and anthropogenic factors, among others broad-scale mining activity. Based on knowledge of the hydrostructural composition of the analysed region and the functioning drainage system of opencast lignite mines, a concept was developed of a change in water supply to the flooded opencast lignite mine, Kazimierz Północ. The task of redirecting waters from the drainage of a nearby opencast mine, Jóźwin IIB, was implemented in 2020. Current observations and forecasts suggest that, owing to the applied solutions, the analysed opencast mine will be flooded in 2023, and not, as previously assumed, at the end of 2021. As a result, groundwater levels in the vicinity of the opencast mine as well as in lakes and rivers within the range of impact of the related depression cone will be restored faster, particularly in the Lake Powidzkie catchment. The objective of the study is to present stages of flooding of the former opencast lignite mine Kazimierz Północ, identify factors determining the process, and describe solutions accelerating it, with a simultaneous environmental impact assessment of the undertaken activities. Full article

In the coal phase-out era, achieving sustainable mine closure is significant and prioritizes targets for the mining industry. In this study, the already closed lignite mine of Kardia, North Greece, is investigated, where the mine void left is naturally filled with water. The viability of different repurposing land uses is evaluated, and the natural water level development inside the mine pit is investigated concerning its future uses. The potential for solar photovoltaic (PV) panels developed on mining land and its surrounding area is evaluated in combination with the application of pumped hydro storage (PHS) technology, utilizing pit lake water. Except for electricity system planning, other end-uses that offer multiple, mutually reinforcing and lasting benefits are investigated, such as recreation parks, terrestrial wildlife, aquaculture and agriculture. All repurposing scenarios are evaluated with regard to the spatiotemporal evolution of the lake, by generating forecasts of the dependent variables (rainfall and temperature) via linear (autoregressive integrated moving average) and non-linear (artificial neural network) models. The prediction of pit lake natural development redefines the new land use layout and the land repurposing decisions. This is essential for strategic planning, considering the Greek lignite mining industry’s priority regarding transitioning from the current coal-based electricity to renewable energy sources (RES) technology. Full article