Search Results (1,549)

As a crucial component in mining engineering, the instability of waste dumps can lead to severe engineering accidents and significant economic losses. This study focuses on the stability of steep slopes in open-pit waste dumps, particularly under short-duration heavy rainfall conditions, and analyzes the stability performance of slopes with different slope ratios. Using a manganese mine waste dump in Guangxi Province as a case study, a 2D numerical model was developed using GeoStudio software (2022.1). The model incorporated local soil parameters and rainfall data to calculate the safety factors of single-step slopes with heights ranging from 5 to 30 m under the maximum local rainfall, which lasted for 10 h. The slope ratios considered were 1:1.5, 1:1.75, 1:2.0, and 1:2.25. The study found that as the slope ratio and rainfall duration increased, the stability of the slope significantly decreased. For slope ratios of 1:1.5, 1:1.75, and 1:2.0, the safety factors dropped below 1.1 as the step height increased. However, for slopes with a ratio of 1:2.25 and step heights ≤ 30 m, the safety factors remained above 1.1, meeting the stability requirements. This research provides a theoretical basis for addressing the stability issues of waste dumps in rainfall-prone regions and for the implementation of stabilization measures in single-step waste dump slopes. Full article

The present investigation introduces a novel approach, using As-Zn-Fe mining tailings (MT) and recycled bottle glass (cullet) to enable the manufacturing of a new glass for ornamental articles, with characteristics similar to those of soda–lime–silicate glass (SLS), and at the same time, immobilizing potentially toxic elements (PTEs) from mining tailings, which cause environmental pollution with severe risks to human health. The glass used was obtained from transparent glass bottles collected from urban waste, which were later washed to remove impurities and then crushed until they reached No. 70 mesh (212 μm) level; in the case of mining tailings, the sample used comes from the ore benefit process, with 96.8% of particles below the No. 50 mesh level (300 μm). Six mixtures were made by varying the composition of the mining tailings and glass, K₂CO₃ and H₃BO₃ as fluxes were also used in constant proportion. The mixtures were melted at 1370 °C, and later, the glass samples were cast on a steel plate at room temperature. The characteristics of the glasses were studied using thermal analysis (TA), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). Likewise, their chemical resistance in acid and basic media and density were evaluated. The results unequivocally demonstrate the feasibility of manufacturing glasses with a light green color, the increase in the content of mining tailings increased the apparent T_g from 625 to 831 °C. Glasses with 17 and 21.3% MT presented lower density values due to a better-polymerized glass structure, attributed to the increase in SiO₂ and Al₂O₃ and the decrease in alkaline oxides, which allowed for the retention of PTEs in their structure. Full article

During surface coal mining, vast amounts of overburden waste materials—called spoils—are excavated and dumped, forming massive heaps, the sustainable exploitation of which is a top priority globally. This study addresses the advanced geotechnical characterization of spoil materials, focusing on lignite mine spoil heaps, which are often ignored due to their highly heterogeneous nature. This research quantifies the spatial variability in spoil materials from a large heap in Greece, highlighting the importance of a robust geotechnical framework for their effective reclamation. Using statistical analysis and variogram modeling, the scale of fluctuation (SoF) was derived for both the vertical and horizontal directions. The SoF values for spoil properties are found to be on the high end of the natural soil range. Vertical correlations are observed for distances over 10 m, occasionally reaching 20 m, indicating significant spatial variability; in the horizontal direction, the SoF reaches up to 285 m. These findings suggest that spoil elements exhibit important spatial dependence, which is critical for their proper design and exploitation. The results provide a basis for future research and the use of advanced numerical tools, such as the random finite element method, to support geotechnical design and the sustainable exploitation of spoil heaps. Full article

This study developed a one-part alkali-activated slag/wood biomass fly ash (WBFA) binder (AAS) for preparing cemented paste backfill (CPB) as an alternative to traditional cement. Through multi-scale characterizations (XRD, FTIR, TGA, rheological testing, and MIP) and performance analyses, the regulation mechanisms of slag/WBFA ratios on hydration behavior, microstructure, and mechanical properties were systematically revealed. Results demonstrate that high slag proportions significantly enhance slurry rheology and mechanical strength, primarily through slag hydration generating dense gel networks of hydration products and promoting particle aggregation via reduced zeta potential. Although inert components in WBFA inhibit early hydration, the long-term reactivity of slag effectively counteracts these negative effects, achieving comparable 28-day compressive strength between slag/WBFA-based CPB (4.11 MPa) and cement-based CPB (4.16 MPa). Microstructural analyses indicate that the disordered gels in AAS systems exhibit silicon–oxygen bond polymerization degrees (950 cm⁻¹) comparable to cement, while WBFA regulates Ca/Si ratios to induce bridging site formation (900 cm⁻¹), significantly reducing porosity and enhancing structural compactness. This research provides theoretical support and process optimization strategies for developing low-cost, high-performance mine filling materials using industrial solid wastes, advancing sustainable green mining practices. Full article

Tailings generated by mining account for the largest world-wide waste from industrial activities. As an element, copper is relatively uncommon, with low concentrations in sediments and waters, yet is very elevated around mining operations. On the Keweenaw Peninsula of Michigan, USA, jutting out into Lake Superior, 140 mines extracted native copper from the Portage Lake Volcanic Series, part of an intercontinental rift system. Between 1901 and 1932, two mills at Gay (Mohawk, Wolverine) sluiced 22.7 million metric tonnes (MMT) of copper-rich tailings (stamp sands) into Grand (Big) Traverse Bay. About 10 MMT formed a beach that has migrated 7 km from the original Gay pile to the Traverse River Seawall. Another 11 MMT are moving underwater along the coastal shelf, threatening Buffalo Reef, an important lake trout and whitefish breeding ground. Here we use remote sensing techniques to document geospatial environmental impacts and initial phases of remediation. Aerial photos, multiple ALS (crewed aeroplane) LiDAR/MSS surveys, and recent UAS (uncrewed aircraft system) overflights aid comprehensive mapping efforts. Because natural beach quartz and basalt stamp sands are silicates of similar size and density, percentage stamp sand determinations utilise microscopic procedures. Studies show that stamp sand beaches contrast greatly with natural sand beaches in physical, chemical, and biological characteristics. Dispersed stamp sand particles retain copper, and release toxic levels of dissolved concentrations. Moreover, copper leaching is elevated by exposure to high DOC and low pH waters, characteristic of riparian environments. Lab and field toxicity experiments, plus benthic sampling, all confirm serious impacts of tailings on aquatic organisms, supporting stamp sand removal. Not only should mining companies end coastal discharges, we advocate that they should adopt the UNEP “Global Tailings Management Standard for the Mining Industry”. Full article

Antimony is a chemical element with diverse uses that falls into the range of a critical raw material. Although it appears in nature as stibnite, the mining of this mineralogical species is rare or uncommon, and it is the element that is basically recovered as a secondary material in the processing of various elements (such as gold and copper). Another source for the recovery of this element is the recycling of Sb-bearing wastes such as batteries and alloys. Once dissolved and in order to recover it from the different leachates, adsorption processes are the ones that seem to have, at least for the scientific community, the highest acceptance. This work reviews the most recent advances (in 2024) in the recovery of antimony from different sources using not only adsorption processes but also other technologies of practical interest. Full article

Oil sands tailings consist of a combination of sand, fine particles, water, and residual unextracted bitumen in varying ratios. The management of these mine waste tailings is largely influenced by their consolidation behavior. Large strain consolidation testing, such as the multi-step large strain consolidation (MLSC) test, is commonly used to determine consolidation properties but requires considerable time. A benchtop centrifuge (BTC) apparatus was proposed to derive the consolidation parameters of the following three clay-rich oil sands tailings slurries: two samples of high-plasticity fluid fine tailings (FFT) and one of low-plasticity FFT. Comparison with the MLSC tests illustrates that the BTC-derived compressibility data closely matched the MLSC test’s compressibility curve within the BTC stress range. However, the hydraulic conductivity from the BTC test was an order of magnitude higher than that from the MLSC test. The consistency of the BTC method and the validation of scaling laws were confirmed through modeling-of-models tests, showing a consistent average void ratio regardless of the specimen height or gravity scale. The influence of the small radius of the BTC was found to be minimal. The limitations of the BTC in the physical modeling of the consolidation behavior are discussed and their impact on the interpretation of the observed consolidation behavior is addressed. Overall, the BTC test provides a rapid method to gain insight on high-water-content slurries’ large strain consolidation behavior. Full article

The precipitation pattern in South Africa is unpredictable and irregularly distributed across the nine provinces. Water resources support agriculture, mining activities, and other social and economic activities in the country. Nevertheless, South Africa is a water-scarce country prompting the urgent need for revitalization to increase water availability. There are major issues with irrigation water security in South Africa’s agriculture sector. Water scarcity, exacerbated by population growth, climate change, and wasteful use, threatens smallholder farmers’ livelihoods. Smallholder farmers encounter difficulties obtaining water despite initiatives to enhance water management, such as poor infrastructure, a lack of funding, and exclusion from choices about water management. This study examines the current water security challenges faced by smallholder farmers in ensuring water security in South Africa. It emphasizes the importance of collaborative networks, inclusive water governance, and innovative irrigation technologies. The study highlights the need for programs and policies that promote cutting-edge irrigation technologies and support smallholder farmers’ participation in water management decisions. Effective solutions require a coordinated approach, involving government, NGOs, and the private sector. Addressing these challenges can improve water security, promote sustainable agricultural development, and enhance food security nationwide effectively and efficiently. Additionally, the study suggests that context-specific solutions be developed, considering the requirements and difficulties smallholder farmers face. This entails funding irrigation infrastructure, assisting and training farmers, and advancing water-saving innovations. Full article

This paper examines sustainable industrial practices in Serbia, particularly in the mining and energy sector, focusing on the potential of flotation tailings and fly ash, as materials with the largest share in disposed waste in Serbia in 2023 (95%). It highlights the environmental challenges of mining waste and explores innovative approaches to waste management within the circular economy framework. The study analyzes the current state of mining waste in Serbia, particularly in copper mining regions in the east of the country. It discusses the potential for metal recovery from waste and its reuse in various industries. The research also investigates the use of fly ash from thermal power plants as a valuable resource in the construction industry and other sectors. The paper reviews existing initiatives and legislation in Serbia in order to promote sustainable mining practices and waste utilization. By presenting case studies and potential applications, the study demonstrates how implementing circular economy principles in the mining sector can contribute to environmental protection, resource conservation, and economic growth in Serbia. The comprehensive overview of the current state in Serbia provides a solid foundation for establishing a higher degree of circularity in the mining and energy sectors. Full article

Gold production poses significant environmental challenges, including resource depletion, CO₂ emissions, and toxic chemical usage. Similarly, improper WEEE management harms the environment. However, WEEE contains valuable metals such as gold, making it central to circular economy (CE) strategies and an alternative to mining. This study assesses the climate impact of pyrometallurgical gold recovery from WEEE using life cycle assessment (LCA). The study found that the carbon footprint of producing gold pyrometallurgically from WEEE is 2000 kg CO₂eq/kg. These emissions are largely tied to the carbon content of waste, meaning that low-carbon energy sources have a limited impact. This creates a conflict between CE goals and CO₂ reduction. Scenario analysis shows that utilizing waste heat for district heating significantly lowers emissions. The other strategies used to improve the environmental performance include separating the plastic fraction before smelting, using biogenic plastic in WEEE, and carbon capture and storage (CCS). Transport accounts for just 10% of the total carbon footprint. Future regulations must address multiple factors—EEE production, waste management, smelter infrastructure, global socioeconomic dynamics, and consumer behavior—as higher recycling rates alone will not solve WEEE challenges. Full article

Reclaiming land after mining activities and ensuring environmental protection are mandatory aspects of the decommissioning process for mining sites. Groundwater assessments, particularly those evaluating vulnerability to contamination using the DRASTIC rank method, are critical tools for guiding and controlling reclamation efforts. By analysing changes in hydrogeological and environmental factors, as well as parameter classes through sensitivity analyses, the DRASTIC method can be optimised to predict the effects of reclamation. Results indicate that reclamation typically decreases groundwater vulnerability, as evidenced by a shallower water table, reduced recharge volume, groundwater flow within new waste rock formations, changes in soil types, lower slopes, and reduced conductivity. Vulnerability changes during reclamation vary spatially, including both decreases and localised increases. Reclamation planning should prioritise groundwater vulnerability assessments to ensure effective land use and environmental protection. Modifications to groundwater-monitoring networks, especially in areas prone to flooding and significant surface changes, are also essential for comprehensive reclamation management. Full article

The current difficult political and economic situation generates the need to seek new sources of energy, and the solution may be to increase biomass of energy crops through using organic–mineral wastes to improve soil quality. The research objectives were to determine the effect of coal gangue (CG) and sewage sludge (SS) based organic–mineral fertilizer (OMF) application on cocksfoot growth and subsequently on biogas and methane production. First, a 6-week vegetation experiment was conducted where degraded soil (DS) taken from the edge of a sand mine in Rokitno was amended with OMF at 1% (DS + 1), 2%, 5%, and 10%. Cocksfoot was sown on such prepared soils. At the end of the first stage of the experiment, plant and soil samples were collected. In cocksfoot, dry shoot and root biomass were determined. The main soil properties and soil dehydrogenases, alkaline phosphatase (ALP), acid phosphatase (ACP), and protease (PROT) activities were analyzed. Next, an anaerobic fermentation experiment was conducted. In batch assay of digestion, cocksfoot collected from arable soil (CS) and from DS + 1% was used. Concerning the pot experiment, there was higher PROT in DS + 5% (by 133%) and DS + 10% (by 417%) compared to CS, and ALP in DS + 10% was higher by 19% than in CS. Shoot dry matter in OMF-amended DS was 107–297% higher than in CS. Among the fermentation experiment, the greatest differences (20–37%) in average daily biogas production between CS and DS + 1% were observed at 2–4 days but methane content in biogas in both variants was similar. Summarizing, fertilizer based on SS and CG can be a valuable substrate for degraded soil and increase in energy crops biomass. Full article

Environmental regulations on lead recycling are becoming increasingly stringent, prompting the search for sustainable alternatives to conventional high-temperature processes. Hydrometallurgical methods in chloride media have emerged as a viable option for recovering lead from mining and urban wastes, including lead anode corrosion residues, zinc leaching residues, and spent lead–acid batteries. This study reviews the key conditions for lead recovery in chloride media, highlighting the variables that optimize lead dissolution, and the potential challenges associated with these processes. The findings indicate that efficient lead recovery requires high chloride concentrations, with acidity playing a critical role depending on the relative concentrations of lead and sulfate in the solution. When lead and sulfate concentrations are similar, stable lead–chloride complexes form within a pH range of 0 to 6.0. However, at higher sulfate concentrations, the pH range narrows significantly to 0 to 2.0, necessitating a more acidic environment for effective dissolution. Chloride media offer a distinct advantage through the formation of stable lead–chloride complexes, whose stability is influenced by chloride concentration, sulfate concentration, pH, and redox potential. Moreover, this approach provides a sustainable alternative that could integrate seawater into industrial processes, particularly in regions facing water scarcity. Full article

Coal gangue slurry filling technology is an effective way of utilizing coal gangue solid waste resources rationally, and its fluidity and sedimentation behavior have an essential influence on filling performance. However, evaluation and optimization methods for the fluidity and sedimentation performance of coal gangue slurry filling materials (CSFMs) are still scarce. In order to solve this problem, based on the fractal grading theory, this paper carried out an experimental study on the influence of the fractal dimension on the flow characteristics of CSFMs, revealed the impact of the fractal dimension on the flow performance of slurry, and constructed a CSFM flow performance evaluation and optimization model based on the fractal dimension. At the same time, the influence of the fractal dimension on solid mass fraction and particle distribution in the CSFM sedimentation process was analyzed using a sedimentation experiment. Combined with fitting analysis and model construction, a CSFM sedimentation performance evaluation method based on fractal dimension D was proposed. The results show that (1) the slump, expansion, and yield stress of CSFMs increased first and then decreased with the increase in the fractal dimension, and the bleeding rate of CSFMs decreased with the rise in the fractal dimension. The analysis of the consistency coefficient of CSFMs shows that the increase in the proportion of fine particles will increase the consistency coefficient. (2) The fitting analysis indicates that the fractal dimension D of CSFMs is negatively correlated with the sedimentation performance P_S. The change in D is most significant in the range of 2.3 to 2.4, where the slurry’s stability is poor. When D exceeds 2.5, the slurry’s stability improves significantly. (3) Based on the evaluation of flow performance and settlement performance, the flow performance and settlement performance of CSFMs with fractal dimensions between 2.50 and 2.59 achieve the best balance, which ensures the reliability of long-distance transportation and construction quality. The research results can provide a reference for the pipeline transportation of whole gangue slurry and have important practical significance for realizing the large-scale disposal of gangue solid waste and green mining of coal mines. Full article

Concrete is known for its high structural performance and workability, but its environmental impact is significant in terms of the utilization of virgin resources and greenhouse gas emissions. To mitigate the negative climate effects of concrete, it is essential to continuously develop and adopt eco-friendly practices in the construction sector. This paper provides an overview of current practices, opportunities, and challenges for developing and adopting eco-friendly concrete. Promising paths for eco-friendly concrete construction include using supplementary cementitious materials (SCMs) instead of energy-intensive traditional cement, incorporating locally available, waste-based materials rather than virgin resources, adopting recycling and reusing techniques, employing advanced technologies, such as performance-enhanced concrete and carbon capture and utilization techniques, etc. Among the studied materials, some waste materials such as rice husk ash, mine tailings, and municipal solid waste ash have found potential and demand further research. The adoption of new materials in concrete and attributing them in practices faces significant social, economic, and regulatory challenges. Addressing these obstacles requires interdisciplinary research and development, the establishment of clear standards and incentives, and educating skilled professionals and efforts to raise social awareness. Full article