Mine Drainage Research Articles

Desulfurization of coal pyrite tailings with ozone

Mining is an important sector of the economy, and in the southern region of Brazil, coal mining stands out. This activity generates waste with a high pyritic content, which causes environmental problems such as acid mine drainage (AMD). Therefore, studies that aim to beneficiate or treat this waste are of high relevance. In this study, an alternative for desulfurizing pyritic waste using ozone was investigated. Ozone treatment of mining tailings suspension was evaluated as a new strategy for sulfur removal. Particle size analysis, sulfate content, ferrous ion concentration (and total iron), pH, Eh, conductivity, and X-ray fluorescence were performed. Furthermore, a kinetic analysis of ozone consumption was established. The behavior of sulfate and hydrogen ion concentrations indicates that sulfuric acid is the main reaction product, and conductivity suggests that ion release is continuous over the ozonation time. A reaction kinetics with ??1.2 was found for ozone depletion, which aids in predicting the dosage to be applied on a larger scale. This study represents a contribution to the search for alternatives for treating pyritic waste and contributes to the understanding of the reaction rate of ozone consumption in this type of reaction.

Perencanaan Tahapan Persiapan Dan Perhitungan Reklamasi Di Lahan Bekas Tambang Air Rikai PT Timah Tbk Kabupaten Bangka

The research location chosen was the Air Rikai ex-mining land, which is an alluvial ex-mining land within the IUP of PT Timah Tbk. The negative impact that arises from mining is in the form of land damage. This research aims to overcome damage and also ensure that reclamation activities can be carried out well. The method used in this research is a quantitative method. The data taken is in the form of soil samples, soil pH and water pH data, topographic data (x,y,z coordinates) and bathymetric data for the depth of the pit. The results of data processing and analysis show that the condition of the land to be reclaimed has an area of 13 Ha and is divided into 2, namely voids with a total area of 1.57 Ha and land area of 11.43 Ha. Land use is carried out by stockpiling overburden with a required volume of overburden of 35,511.54 m³. Land leveling with a volume of pushed soil of 35,280 m³. Arrangement of the edge of the pit with a volume of soil moved of 230.29 m³. Construction of drainage channels with an excavation volume of 214.59 m³. Installation of concrete buis type culverts with dimensions of 50 x 50 cm and a length of 50 cm. In the revegetation, 1,517 oil palm trees were planted, then 463 sea cypress trees were planted along the underside and LCC seeds to help loosen the soil. Treating acid mine drainage with 350 water hyacinths. The costs required for reclamation are divided into 2, namely, Direct Costs and Indirect Costs. The direct costs required are IDR 679,286,160 and the indirect costs required are IDR 213,975,140. The total costs required for reclamation of land with an area of 13 Ha are IDR 893,261,300.

Reproductive Success of Tree Swallows at Abandoned Mine Drainage Treatment Ponds

Abandoned mine drainage treatment ponds could have contrasting effects on the reproductive success of birds living in the vicinity. The ponds and associated vegetation may, like any other body of freshwater, provide beneficial habitats for the insects that the birds use to feed their young; or instead, the ponds may act as an ecological trap, attracting the birds to a habitat that is poor in quality and negatively impacting their productivity. We monitored nests of an aerial insectivore, the Tree Swallow (Tachycineta bicolor), to determine whether the distance between the ponds and the nests affected various reproductive parameters including clutch size, hatch rate, number of nestlings, nestling size and mass, number of fledglings, fledging rate, and fledge date. Data were collected over two breeding seasons (2022 and 2023) from a swallow population in southwestern Pennsylvania, USA. We found that the nests closest to the treatment ponds had significantly more nestlings and fledglings, earlier fledge dates, and a better fledging rate when compared to nests that were more distant from the ponds. However, all these parameters were well below previously published values, which suggests that the mine drainage ponds provide good nesting habitats relative to what is available in the region but that they do not represent high-quality habitats for this species overall.

Deciphering microbial metabolic interactions and their implications for community dynamics in acid mine drainage sediments

The microbially-mediated reduction processes have potential for the bioremediation of acid mine drainage (AMD), which represents a worldwide environment problem. However, we know little about the microbial interactions in anaerobic AMD sediments. Here we utilized genome-resolved metagenomics to uncover the nature of cooperative and competitive metabolic interactions in 90 AMD sediments across Southern China. Our analyses recovered well-represented prokaryotic communities through the reconstruction of 2625 population genomes. Functional analyses of these genomes revealed extensive metabolic handoffs which occurred more frequently in nitrogen metabolism than in sulfur metabolism, as well as stable functional redundancy across sediments resulting from populations with low genomic relatedness. Genome-scale metabolic modeling showed that metabolic competition promoted microbial co-occurrence relationships, suggesting that community assembly was dominated by habitat filtering in sediments. Notably, communities colonizing more extreme conditions tended to be highly competitive, which was typically accompanied with increased network complexity but decreased stability of the microbiome. Finally, our results demonstrated that heterotrophic Thermoplasmatota associated with ferric iron and sulfate reduction contributed most to the elevated levels of competition. Our study shed light on the cooperative and competitive metabolisms of microbiome in the hazardous AMD sediments, which may provide preliminary clues for the AMD bioremediation in the future.

A systematic literature review of sustainable water management in South Africa

Addressing global challenges of inequitable and unsustainable natural resource management is imperative. South African water management serves as a critical case study allowing for the deep exploration of the intricate complexities surrounding these issues. South Africa's apartheid era witnessed inequitable water distribution and, despite the efforts made through the post-apartheid National Water Act of 1998 to prioritise equity and sustainability, challenges still persist in its implementation. This review aims to bridge knowledge gaps in sustainable water management in South Africa, focusing on environmental justice and sustainable development within the framework of the three pillars of sustainability. Through a systematic literature review of 57 scientific papers published in the Web of Science database between 1995 and 2021 this study aims to provide a comprehensive examination of the complex dynamics shaping water management in South Africa. Major themes, challenges, and solutions in sustainable water management are identified, emphasising the importance of stakeholder interactions, insufficient collaboration, and a lack of capacity building. The study also explores water policy implementation, environmental impacts of business, particularly in agriculture and mining, and the management of freshwater sources and their overexploitation. Economically, the mining industry's role and associated challenges such as acid mine drainage and water use competition are assessed. The Water-Energy-Food Nexus's influence on water management, water pricing efficiency, user willingness to pay, and the potential of decentralised systems and corporate social responsibility are also explored. With South Africa facing urgent challenges of water scarcity and resource management, integrated approaches that consider environmental, social, and economic dimensions, alongside robust multi-stakeholder collaboration, are essential. This review offers valuable insights for policymakers, water managers, and researchers working toward a sustainable water future in South Africa.

The application of transfer machine learning to predict and impute missing sulphate levels in different Acid Mine Drainage treatment plants

An accurately pre-trained stacking ensemble machine learning regressor was used to predict sulphate levels in two other Acid Mine Drainage (AMD) treatment plants using Transfer Learning (TL). The model was trained on the large Central Rand (CR) water quality dataset and was used to predict and impute the sulphate levels in the scanty East Rand (ER) and West Rand (WR) datasets which would not have been sufficient to train ML models from scratch. TL was successfully used to overcome this barrier and rapidly predicted sulphate levels in the East Rand and West Rand plants using the pre-trained model and achieved a high level of accuracy (Mean Squared Error:0.00124, Mean Absolute Error:0.0290 and R2:0.963) for the East Rand plant when comparing the predicted and true sulphate values. No true sulphate values existed for the West Rand plant; however, TL was successful in imputing these missing values and rapidly completed the West Rand dataset by providing the historic sulphate levels. This was possible due to the high degree of similarity between all domains (treatment plants) since they had similar geographic locations, the same treatment process, possessed the same important features and had the same relationships between variables. TL was successful in providing three accurate datasets for AMD sulphate levels, an important accomplishment towards having reliable data for use in design of experiments aimed at recovering valuable resources such as elemental sulphur, gypsum and important metals from AMD.

Effects of Acid Mine Drainage Leakage on Bacterial Communities in Desert Grassland Soil Profiles

Acid mine drainage （AMD） is of great concern owing to its safety hazards and environmental risks. However, little is known about the effects of AMD leakage on soil physicochemical properties and bacterial communities in ecologically fragile desert steppe soils, especially in the soil profile. Therefore, an AMD-contaminated profile and clean profile were used as research objects respectively to investigate the effects of AMD on soil physicochemical properties and bacterial community composition, structure, and interactions in soil layers at different depths of desert grassland and, based on this, to analyze the driving factors of bacterial community changes. The results showed that AMD significantly decreased the pH and increased electrical conductivity （EC） and heavy metal content in the upper （0-40 cm） soil layer of the profile. The AMD-contaminated profile bacteria were dominated by Proteobacteria, Firmicutes, and Actinobacterota, whereas clean profile bacteria were dominated by Firmicutes and Bacteroidota, with Thermithiobacillus and Alloprevotella being the biomarkers for the contaminated and clean profiles, respectively. AMD contamination significantly reduced bacterial diversity and significantly altered bacterial community structure in the upper soil layers of the profile. The results of redundancy analysis showed that soil physicochemical properties explained 57.21% of the variation in bacterial community changes, with EC, TP, TN, As, Zn, and Pb being the main drivers of bacterial community changes. Network analyses showed that AMD contamination increased profile complexity, modularity, and intra-community competition, thereby improving bacterial community stability and resilience. In conclusion, the study provided useful information on the effects of AMD pollution on soil physicochemical properties and bacterial communities in desert steppe soils, which may help to improve the understanding of the ecological hazards of AMD pollution on soils in extreme habitats.

Ferrous iron oxidation efficiency and kinetics by indigenous iron-oxidizing bacteria in acid mine drainage

Biological Fe(II) oxidation by iron-oxidising bacteria (FeOBs) at low pH is a cost-effective treatment for acid mine drainage (AMD). However, treatments based on this process are limited because of uncertainties regarding the ability and rate of oxidation of Fe(II) from AMD. In the present study, an indigenous FeOBs consortium was enriched in AMD, and its ability to oxidise Fe(II) is described. The bio-oxidation rate of Fe(II) was 39.1 mg/(L·h) under optimal culture conditions [35 ℃, pH 2.0, 500 mg/L Fe(II)]. In addition, the oxidation rate equation of Fe(II) could be fitted to a zero-order kinetic model, indicating that Fe(II) was oxidised at a constant rate. Furthermore, a continuous-flow bioreactor was developed to simulate the Fe(II) oxidation efficiency of indigenous FeOBs for in situ AMD biological treatment. The maximum Fe(II) oxidation rate was 22.8 mg/(L·h) when the influent Fe(II) load was 32.3 mg/(L·h). Acidithiobacillus and Acidiphilium were the dominant species contributing to Fe(II) oxidation in the bioreactor, accounting for 67.7 % and 32.8 %, respectively. The results will help promote the application of FeOBs in AMD treatment.

Energy and copper recovery from acid mine drainage by microbial fuel cells. Effect of the hydrochar doping on carbon felt anodes

This work investigates the performance of a Microbial Fuel Cell (MFC) for Acid Mine Drainage (AMD) treatment using bare and hydrochar-doped carbon felt (CF) anodes. Hydrochar was synthesized through hydrothermal carbonization of Spergularia rubra, followed by activation at 500 °C, resulting in improved O/C and H/C ratios of 0.26 and 0.78, respectively. The study reveals that doping CF anodes with non-activated and activated hydrochar significantly enhances copper recovery and electricity generation. The highest copper recovery rate of 16.0 mg/L h−1 was achieved with activated hydrochar-doped CF (CFaH) anodes, followed by 10.6 mg/L h−1 with non-activated hydrochar-doped CF (CFnaH) anodes, and 7.1 mg/L h−1 with bare CF anodes. Hydrochar doping also improved the maximum current density to 0.21 mA cm−2 compared to 0.16 mA cm−2 with bare CF anodes. These results demonstrate the potential of hydrochar-doped CF anodes for efficient metal and energy recovery from AMD, offering a sustainable and energy-efficient alternative to conventional methods.

Hydrogeology and groundwater control at Chambishi mine, Zambia

The hydrogeological conditions in the Chambishi mine area in Zambia. were investigated. Chambishi is a very wet mine and groundwater discharge costs are high. The research goal was to identify methods to reduce the discharge costs without greatly affecting the mining process. Hydrogeological data was obtained from measurements in drill-holes and from drill cores. The differences in structural deformation in different areas determine whether a layer of rock is an aquifer. In the mine region, the Lower Roan Group ore shale and quartz-sandstone unconformably lie on the basal schist and granite aquifuge. The Upper Roan Group dolomite is continuously distributed over a large area around the orebody. This dolomite is the main target of groundwater control efforts, and its water yield is also influenced by the deformation intensity. Based on the observations, backfilling was gradually adopted to appropriately safeguard the integrity of the aquifuge above the orebody. The overlapping relationship between the aquifer and aquifuge has been utilized to increase mine drainage efficiency. This measure has not only greatly reduced the costs of mine drainage, but also improced protection of the groundwater environment. The old drill-holes that were not sealed after exploration drilling were grouted. Further, possible water-conducting fracture zones were investigated. Cover drilling towards the suspected zone was conducted to prevent the high-pressure groundwater from shallower aquifers from entering stopes in deep areas of the mine.

Response surface modelling and optimization for copper removal from acid mine drainage using oxidized Himalayan pine needle biochar

ABSTRACT This study aims to investigate and compare the adsorption behaviour of pine needle biochar (PNB) and H2O2-oxidized PNB (OPNB) in eliminating Cu(II) from acid mine drainage. The PNB and OPNB adsorbents undergo comprehensive characterization through various techniques (BET, FTIR, SEM, and pHPZC). A central composite design was employed for designing experiments and optimizing the impact of process factors (metal concentration, adsorbent doses, contact time, and pH) on adsorption capacity. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetics models as well as Langmuir, Freundlich, and Temkin isotherm models were used to analyze the experimental data. Langmuir isotherm best fit (R2 > 0.99) the experimental data and adsorption capacities of 29.49 and 102.04 mg/g, were determined for PNB and OPNB, respectively. Under optimized experimental conditions, desorption studies revealed the reusability of OPNB about 80% even after four cycles. Fixed-bed column experiments were conducted at ambient temperature with an initial Cu(II) concentration of 125 mg/L and 5.0 g of adsorbent, utilizing a flow rate of 1 mL/min for both PNB and OPNB. These results indicate that oxidized biochar, synthesized for Cu(II) remediation, not only addresses Himalayan pine needle concerns sustainably but also exhibits potential applicability for removing other metal ions from aqueous environments.

Remediation of AMD based on hydrogeochemical zonation: A typical metal mine in China

Mining activities disrupt the natural oxidative balance underground, increasing the oxidation of metal sulfides like pyrite. This process leads to the formation of highly acidic mine drainage (AMD) with elevated concentrations of iron (Fe) and sulfate (SO42−). However, generic plugging and backfilling methods, when applied without considering the specific post-mining oxidative environments of different metal mines, often yields minimal results. To clarify the distribution of the underground redox environment after mining of a metal mine in Dexing, China, fifteen water samples from flood and dry periods, as well as fifteen borehole samples, were collected for hydrogeological and chemical analysis. For the first time, the study proposed that the redox zone could be identified and delineated through vertical analysis of water storage media, mineral composition, and hydrochemical characteristics. A hydrogeochemical cause model was constructed, revealing that AMD formation primarily occurs in oxidative and transition zones. Based on the redox zone characteristics of the study area, actual engineering sealing was performed on the oxidation and transition zones of cavity No. 23. As a result, the pH increased from 2.5 before remediation to 4.5, indicating a reduction in acidity. The concentrations of SO42− and Fe significantly decreased, reducing from 1360.0 mg/L and 147.0 mg/L before treatment to 726.0 mg/L and 23.6 mg/L after treatment; the total decrease amounting to 46.6 % and 84.0 %, respectively. The concentrations of Mn and Cu similarly, decreased by 10.7 % and 15.6 %, respectively. This study provides a novel approach and valuable reference for the refined identification and classification of redox zones after metal mine exploitation, as well as for the targeted plugging and treatment of cavities that produce AMD.

Assessment of Acid Mine Drainage’s Impact on Makhat’s Watershed Plants (Taza Province, Morocco)

Assessment of Acid Mine Drainage’s Impact on Makhat’s Watershed Plants (Taza Province, Morocco)

Enrichment of dissolved metal(loid)s and microbial organic matter during transit of a historic mine drainage system

Water quality degradation by decommissioned mining sites is an environmental issue recognized globally. In the Ore mountains of Central Europe, a wide array of contaminants is released by abandoned under- and aboveground mining sites threatening the quantity and quality of surface and groundwater resources. Here, we focus on the less-explored internal pollution processes within these mines involving organic carbon and microorganisms in trace metal(loid)s mobilization processes. Over an 18-month period, we conducted hydrological and biogeochemical monitoring at the Reiche Zeche mine, a former lead-zinc-silver mine, in Germany, reaching 230 meters below ground, well below the critical zone. Our results show strong seasonal fluctuations in water availability, concentrations of metal(loid)s, pH, and dissolved organic matter (DOM) components across multiple depths. Excess metal(loid) presence during high flow conditions indicated mobilization behavior deviating from conservative dilution. Our findings reveal strong positive correlations between metal(loid) variability and pH (0.894), and between metal(loid) variability and the DOM fluorescent component C2 (-0.910), a proxy for microbial activity. Accordingly, the microbial processes may significantly contribute to the observed metal(loid) composition and fluxes. By elucidating the intricate roles of hydrological and biogeochemical factors in trace metal(loid) mobilization, our research offers a comprehensive framework for improving mine water management and remediation, potentially informing global environmental policies and sustainable mining practices.

The Application of Atomic Spectroscopy Techniques in the Recovery of Critical Raw Materials from Industrial Waste Streams, Part II

This month’s column is Part 2 of a contribution from my daughter Glenna, who recently completed her PhD studies in Environmental Science from the University of Copenhagen in Denmark. Her article explores the current landscape of global critical raw materials (CRM) trends in research and the applications of atomic spectroscopy (AS), including inductively coupled plasma–mass spectrometry (ICP-MS), inductively coupled plasma–optical emission spectrometry (ICP-OES), and X-ray analytical techniques in their identification of diverse industrial and environmental media, which have been essential in method validation and quantification of CRMs in complex matrices presenting high risks of interference. Some important examples to be presented include rare earth elements (REEs) in water leaching purification (WLP) residues that co-occur with radioactive materials; REEs and other metals in acid mine drainage (AMD) environments; REEs in coal combustion (fly ash) residues; arsenic (As) from groundwater treatment sediment; and platinum-group elements (PGEs) from sewage sludge. The article also classifies the different techniques in use at each stage of the CRM recovery train, investigates present challenges to each analytical method, and discusses the problem-solving tools used.

A novel nanofiltration membrane with a dual-charged layer to simultaneously remove anions and cations from acid mine drainage

A novel nanofiltration (NF) membrane with a positively and negatively dual-charged layer was finely designed in this study. The membrane was prepared by co-deposition of 4-tert-butylpyrocatechol (TBC) and polyethyleneimine (PEI) and electrostatic interaction to assemble positively and negatively charged functional layers on a substrate which is polyamide (PA)-based NF membrane. The NF membrane achieved excellent retention capacity through the combined effects of Donnan repulsion and electrostatic field trapping. The prepared membrane had a dense but thin surface layer with an average pore size of 0.84 nm, enabling an improved membrane flux of 8.66 L/(m2·h·bar) and high rejection to divalent inorganic salt ions (93.56 % Mg2+, 99.56 % SO42-). The membrane was used to treat acid mine drainage (AMD) and achieved an excellent retention capacity for ions in AMD (93.25 % Mg2+, 91.58 % Ca2+, 94.22 % Mn2+, 95.96 % SO42-), meeting industrial wastewater discharge standards. In addition, the NF membrane demonstrated good anti-fouling performance during the AMD treatment and significant potential for environmental remediation applications.

Selective recovery of europium from real acid mine drainage using modified Cr-MIL and SBA15 adsorbents

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal–organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost–benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD.

Acid Mine Drainage Treatment with Organic Waste in Constructed Wetlands: Effluent Recirculation

Acid Mine Drainage Treatment with Organic Waste in Constructed Wetlands: Effluent Recirculation

Assessment of metal(loid) and natural radionuclide pollution in surface sediments of an estuary affected by mining and phosphogypsum releases

The prolonged impact over the Tinto River estuary by both the significant pollution by acid mine drainage (AMD) affecting this river and the polluted releases from phosphogypsum (PG) piles has led to the severe environmental degradation of this ecosystem. The aim of this work was to assess the current environmental quality of the Tinto River estuary through the study of the spatial distribution of metal(loid)s and natural radionuclides in the surface sediments from the channel edge. The sediments contain mean concentrations 5–20 times higher than the background values for pollutants such as Zn, As, Cu, Pb, or U, and up to two orders of magnitude higher for P. The studied sediments are heavily polluted by toxic heavy metals and metalloids (Pb, Zn, Cu, and As) according to the US EPA guidelines. Most of the analyzed sediment samples are also strongly polluted by long-lived natural radionuclides, mainly U-isotopes and 210Pb with concentrations up to one order of magnitude higher than unpolluted sediments, mostly due to the contribution by the PG leachates. The enrichment factors (EF) were extremely high (EF > 50) for As and very severe enrichment (25 ≤ EF < 50) for P, Cd, Zn, Cu, and Pb.

PENGARUH REVEGETASI TERHADAP SIFAT-SIFAT TANAH PADA LAHAN BEKAS TAMBANG TEMBAGA DI NUSA TENGGARA BARAT

Copper mining activities mainly using open-pit techniques, lead to environmental issues such as overburden waste in waste dump areas that have potential to generate acid mine drainage (AMD), which can decrease soil pH and increase heavy metal toxicity. Reclamation efforts, including revegetation using pioneer plants and cover crops are necessary to restore degraded land in waste dump areas. The aim of this research is to analyze soil physical and chemical properties improvement after revegetation on copper post-mining land as an evaluation and to provide recommendations for future reclamation. The research was carried out by analyzing and interpreting laboratory data from soil observations in revegetation areas for the 2016, 2018, 2019 and 2020 planting years, as well as natural forests belonging to PT. Amman Mineral Nusa Tenggara. Revegetation of copper post-mining land does not show a significant improvement in soil physical properties because improving physical properties takes quite a long time, especially in post-mining areas with heavy structural damage. Soil chemical properties analysis shows that revegetation can increase base saturation (BS), cation exchange capacity (CEC), exch-Ca, exch-Mg, and reduce soil Al saturation. In contrast, soil pH, organic-C, total-N, and soil available-P in the revegetation area did not increase as the revegetation age increased. The effect of revegetation appears to be more significant at the age of 2 to 3 years. However, based on the Tukey test, the age of revegetation mostly does not have a significant effect on enhancing soil chemical properties.