Search Results (85)

To address the limitations of traditional hardened concrete road surfaces in coal mine tunnels, which are prone to damage and entail high maintenance costs, this study proposes using modular concrete blocks composed of fly ash and coal gangue as an alternative to conventional materials. These blocks offer advantages including ease of construction and rapid, straightforward maintenance, while also facilitating the reuse of substantial quantities of solid waste, thereby mitigating resource wastage and environmental pollution. Initially, the mineral composition of the raw materials was analyzed, confirming that although the physical and chemical properties of Liangshui Well coal gangue are slightly inferior to those of natural crushed stone, they still meet the criteria for use as concrete aggregate. For concrete blocks incorporating 20% fly ash, the steam curing process was optimized with a recommended static curing period of 16–24 h, a temperature ramp-up rate of 20 °C/h, and a constant temperature of 50 °C maintained for 24 h to ensure optimal performance. Orthogonal experimental analysis revealed that fly ash content exerted the greatest influence on the compressive strength of concrete, followed by the additional water content, whereas the aggregate particle size had a comparatively minor effect. The optimal mix proportion was identified as 20% fly ash content, a maximum aggregate size of 20 mm, and an additional water content of 70%. Performance testing indicated that the fabricated blocks exhibited a compressive strength of 32.1 MPa and a tensile strength of 2.93 MPa, with strong resistance to hydrolysis and sulfate attack, rendering them suitable for deployment in weakly alkaline underground environments. Considering the site-specific conditions of the Liangshuijing coal mine, ANSYS 2020 was employed to simulate and analyze the mechanical behavior of the blocks under varying loads, thicknesses, and dynamic conditions. The findings suggest that hexagonal coal gangue blocks with a side length of 20 cm and a thickness of 16 cm meet the structural requirements of most underground mine tunnels, offering a reference model for cost-effective paving and efficient roadway maintenance in coal mines. Full article

Increasing water scarcity in arid regions has prompted the mining industry to develop strategies to maximize water recovery and reuse, especially in tailings treatment processes. In this context, the present investigation evaluated the effects of sodium polyacrylate (NaPA) on the compressibility and viscoelasticity of clayey tailings in the presence of hard water containing calcium and magnesium. To this end, clayey slurries were analyzed using rheological tests (rheograms and oscillatory viscoelasticity), zeta potential measurements, and compressibility tests using batch centrifugation. The yield stress was determined using the Herschel–Bulkley model, while the compressive yield stress (Py(Φ)) was calculated as a key indicator to characterize the degree of sediment consolidation. The results showed that NaPA, due to its anionic nature and high degree of ionization at pH 8, induces effective particle dispersion by increasing electrostatic repulsion and decreasing the interaction force between particles, which reduces both rheological parameters and compressive yield stress. For the 70/30 quartz/kaolin mixture, the yield stress decreased from 70.54 to 61.64 Pa in CaCl₂ and from 57.51 to 52.95 Pa in MgCl₂ in the presence of NaPA. It was also observed that suspensions in the presence of magnesium ions presented greater compressibility than those with calcium, attributable to the greater hydration radius of magnesium (10.8 Å), which favors less dense and more easily deformable network structures. Furthermore, a higher proportion of kaolin in the mixture resulted in higher yield stresses, a product of the clay’s laminar structure, colloidal size, and high surface area, both in the absence and presence of NaPA. Overall, the results show that incorporating NaPA significantly improves the compressibility and rheology of clayey tailings in hard water, offering a promising alternative for optimizing water recovery and improving tailings management efficiency in the context of water restrictions. Full article

This review aims to increase attention on present water quality issues on Central Asia, finding gaps in the literature on ways to address treatment needs, and help ensure future use of Central Asia surface waters and groundwater for all beneficial uses. Central Asia is a landlocked region known for its harsh climatic conditions and scarce water resources, despite being home to some of the world’s largest internal drainage basins. The available literature suggests that increasing salinity has rendered water unsuitable for irrigation and consumption; hazardous trace elements are found throughout Central Asia, most often associated with mining and industrial sources; and that legacy pesticides influence water quality, particularly in agriculturally influenced basins. This study also focuses on the effects of municipal and industrial wastewater discharge. Additionally, the impact of inadequately treated wastewater on water resources is analyzed through a review of available data and reports regarding surface and groundwater quantity and quality. Given the challenges of water scarcity and accessibility, the reuse of treated wastewater is becoming increasingly important, offering a valuable alternative that necessitates careful oversight to ensure public health, environmental sustainability, and water security. However, due to insufficient financial and technical resources, along with underdeveloped regulatory frameworks, many urban areas lack adequate wastewater treatment facilities, significantly constraining their safe and sustainable reuse. Proper management of wastewater effluent is critical, as it directly influences the quality of both surface and groundwater, which serve as key sources for drinking water and irrigation. Due to their persistent and biologically active nature even at trace levels, we discuss contaminants of emerging concern such as antibiotics, pharmaceuticals, and modern agrochemicals. This review thus highlights gaps in the literature reporting on impacts of wastewater inputs to water quality in Central Asia. It is recommended that future research and efforts should focus on exploring sustainable solutions for water quality management and pollution control to assure environmental sustainability and public health. Full article

Mining and stone processing activities generate a large amount of various types of waste. Among these, Stone Waste Sludge (SWS) constitutes 22.5 percent of the raw material processed and is disposed of by delivering it to now disused quarries with significant landscape and environmental consequences. This paper describes research aimed at identifying the possible uses of this waste, transforming it from a waste to a resource for the production of building blocks. The production of such building blocks is based on historical preparations of mixtures for artificial stone and is developed through an experimental approach and a simple and economical production methodology. Mixes consisting mainly of SWS and Portland cement (PC) were designed and tested. The aggregates and PC were mixed, wetted, and compacted under high pressure in special molds to form the specimens. The design of the mixtures and related tests aimed to define the process parameters considered such as the amount of water (W), the ratio of PC to SWS, and the compaction pressure. The compressive strength of the manufactured specimens at the age of 28 days was identified as the response variable. The results indicated that all of the mixtures had high mechanical strength values even when using high amounts of SWS relative to the amount of PC and that all of them have excellent characteristics for use as building elements in construction. This implies that such waste has an excellent potential for large-scale reuse in construction and encourages further research and testing, both in terms of the thermo-hygrometric properties of such elements and in terms of LCA analysis. Full article

The sustainable development of building materials is based on reusing by-products to reduce environmental impact and promote alternatives to traditional materials. In this study, geopolymers were developed from by-products of the mining, ceramic, and thermal industries: slate stone cutting sludge (SSCS) and chamotte (CH) as aluminosilicate sources, and olive stone bottom ash (OSBA) as an alkaline activator, combined with sodium silicate (Na₂SiO₃). Eight geopolymer families were prepared with constant amounts of SSCS and CH and varying proportions of OSBA/Na₂SiO₃ (0.88–1.31). The evaluation phase included physical, chemical, mechanical, and microstructural tests. The results showed that the optimum geopolymer formulation (GP E) contained 25% SSCS, 15% CH, and 19% OSBA with a Na₂SiO₃/OSBA ratio of 1.0, achieving a compressive strength of 24.12 MPa after 28 days of curing. GP E also showed the lowest porosity (19.54%), minimal water absorption (6.86%), and favorable thermal conductivity (0.688 W/mK). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) confirmed the formation of dense and homogeneous matrices. These results demonstrate the feasibility of manufacturing geopolymers using SSCS, CH, and OSBA as substitutes for traditional binders, promoting sustainable practices, reusing industrial by-products, and reducing carbon emissions in construction. Full article

The use of pre-concentration and optimization of concentration methods have been the focus of the modern mineral industry. Sensor-based sorting equipment and flotation are key players in that movement. This study provides an overview of the main sensor-based sorting techniques and their uses, focusing on sulfides, addressing performance analysis methodologies, and giving the advantages and limitations of the method. An overview of the flotation technique is also presented, covering its basic principles of operation, as well as its main applications in sulfides, its interactions with pre-concentration, and some opportunities and perspectives on the method, such as water reuse impacts, tailing reprocessing, etc. Case studies are presented addressing the influence of the techniques on each other and some future prospects for the mining sector, such as deep-sea mining (DSM) and the use of artificial intelligence (AI). Full article

The increasing global demand for metals, driven by technological progress and the energy transition, has led to an acceleration in the expansion of the mining and metallurgical industry, resulting in an increase in the generation of mine tailings. This waste, which is of heterogeneous composition and has high contaminant potential, represents significant environmental and social challenges, affecting soils, water, and the geotechnical stability of tailings. The accumulation of these mine tailings poses a problem not only in terms of quantity, but also in terms of physicochemical composition, which exacerbates their environmental impact due to the release of heavy metals, affecting ecosystems and nearby communities. This article reviews the potential of geopolymerization and 3D printing as a technological solution for the management of tailings, offering an effective alternative for their reuse as sustainable building materials. Alkaline activation of aluminosilicates facilitates the formation of N–A–S–H and C–A–S–H cementitious structures, thereby providing enhanced mechanical strength and chemical stability. Conversely, 3D printing optimizes structural design and minimizes material consumption, thereby aligning with the principles of a circular eco-economy and facilitating carbon footprint mitigation. The present study sets out to compare different types of tailings and their influence on geopolymer reactivity, workability, and mechanical performance. In order to achieve this, the study analyses factors such as the Si/Al ratio, rheology, and setting. In addition, the impact of alkaline activators, additives, and nanoparticles on the extrusion and interlaminar cohesion of 3D printed geopolymers is evaluated. These are key aspects of their industrial application. A bibliometric analysis was conducted, which revealed the growth of research in this field, highlighting advances in optimized formulations, encapsulation of hazardous waste, CO₂ capture, and self-healing geopolymers. The analysis also identified technical and regulatory challenges to scalability, emphasizing the necessity to standardize methodologies and assess the life cycle of materials. The findings indicated that 3D printing with tailings-derived geopolymers is a viable alternative for sustainable construction, with applications in pavements, prefabricated elements, and materials resistant to extreme environments. This technology not only reduces mining waste but also promotes the circular economy and decarbonization in the construction industry. Full article

This study developed a semi-passive treatment system for manganese (Mn)- and zinc (Zn)-containing mine water by repurposing a neutralization tank into a biologically active stirred reactor. Laboratory-scale experiments demonstrated efficient removal of Mn²⁺ (>97%) and Zn²⁺ (>80%) with hydraulic retention times (HRTs) as short as 6 h—significantly faster than traditional passive systems. XRD and XANES analyses identified the predominant formation of birnessite, a layered Mn oxide, during Mn²⁺ oxidation, with Zn co-treatment promoting the precipitation of Zn-containing carbonates. Despite decreasing crystallinity of birnessite over time, microbial activity, dominated by Mn-oxidizing genera, such as Sphingomonas, Pseudonocardia, Sphingopyxis, Nitrospira, and Rhodobacter, persisted in the presence of Zn²⁺, ensuring system stability. Importantly, the low leachability of Mn and Zn from the resulting sludge in TCLP tests confirmed its environmental safety and potential for reuse. By leveraging existing infrastructure and microbial biomineralization, this system bridges the gap between passive and active treatments, significantly reducing treatment footprints and operational costs. These findings highlight the potential of repurposing mine water treatment tanks as a scalable, cost-effective solution for sustainable mine water remediation. Full article

The increasing global demand for critical minerals, driven by rapid population growth and the widespread adoption of low-carbon technologies, electric vehicles, and clean energy systems, highlights the urgent need for sustainable resource management. Mine tailings, traditionally considered waste, are now being recognized as valuable secondary sources for mineral recovery. This paper compiles a comprehensive review of the four short- and mid-term critical minerals (lithium, cobalt, nickel, and rare earth elements) and provides insights regarding their recovery with a focus on the latest technological advancements. By exploring key innovations in separation processes, the review demonstrates how these technologies are addressing supply chain bottlenecks while simultaneously reducing the environmental footprint of mining operations. The paper also advocates for a holistic approach to mine waste management, integrating mineral recovery with environmental remediation. It emphasizes the dual benefits of recovering valuable resources while purifying contaminated water and mitigating pollution risks. The proposed circular economy model suggests a sustainable blueprint for managing mine tailings, emphasizing resource reuse, waste reduction, and economic viability. Full article

Since 2019, the NextGen pilot wastewater treatment unit—also known as the NextGen Sewer Mining concept—has been operating at the Athens Plant Nursery, transforming sewage from Athens’ central network into irrigation water and compost. This unit produces resources for plant growth through membrane bioreactors (MBRs) and aerobic sludge digestion. This study experimentally evaluates the effects of NextGen reused water and compost on two common ornamental plant species in Athens, Pittosporum tobira (Angelica) and Myrtus communis (Common Myrtle), compared to the use of tap water and red soil without additional fertilization. The results indicate that NextGen reused water combined with compost significantly promotes both height and weight growth in these plants. However, by the end of the experiment, compost fertilization had a greater effect on the height and weight growth of both Angelica and Myrtus plants when applied independently and watered with tap water, compared to the use of NextGen reused water combined with red soil. Notably, none of the 96 plants withered throughout the experiment, indicating that promising and sustainable technologies like the concept of Sewer Mining can effectively replace conventional and environmentally outdated methods of plant nutrition and irrigation by producing reused water and compost. Full article

Integrating circular economy (CE) principles into mining practices offers a promising path toward reducing environmental harm while promoting sustainable resource management. This shift boosts the industry’s efficiency and profitability and aligns it with global sustainability goals. This paper delves into strategies for closing material loops, such as waste valorization, resource recovery from mine tailings, and water reuse in mining processes. Additionally, this study highlights innovative technologies and their potential to transform traditional linear practices into sustainable, circular systems. This paper emphasizes the importance of strong collaboration among industry stakeholders and policymakers, including mining companies, researchers, and local communities, for the implementation of CE principles. This paper also discusses the role of emerging digital tools, automation, and artificial intelligence in advancing circular practices and improving operational efficiency. By exploring the economic, environmental, and social benefits of the CE, this paper demonstrates how these practices can contribute to sustainable mining. It addresses key challenges, including technological, economic, and regulatory hurdles, and offers recommendations for overcoming them to pave the way for a more sustainable and resilient mining industry. Full article

The large numbers of ion exchange resins used in various industries (food, pharmaceutitics, mining, hydrometallurgy), and especially in water treatment, are based on cross-linked polystyrene and divinylbenzene copolymers with functional groups capable of ion exchange. Their advantage, which makes them environmentally friendly, is the possibility of their regeneration and reuse. Taking into account the wide application of these materials, styrene–divinylbenzene resin with a quaternary ammonium functional group, Amberlite^®IRA402, was characterized using a well-known and widely used method, FT-IR spectroscopy. As the infrared spectrum of the tested ion exchange resin was rich in bands, its detailed assignment was supported by quantum chemical calculations (DFT/B3LYP/6-31g** and DFT/PCM/B3LYP/6-31g**). Using appropriate 3D models of the resin structure, the optimization of geometry, the infrared spectrum and atomic charges from an atomic polar tensor (APT) were calculated. A detailed description of the infrared spectrum of Amberlite^®IRA402 resin (Cl⁻ form) in the spectral range of 4000–700 cm⁻¹ was performed for the first time. The charge distribution on individual fragments of the resin structure in aqueous solution was also calculated for the first time. These studies will certainly allow for a better understanding of the styrene–divinylbenzene resin interaction in various processes with other substances, particularly in sorption processes. Full article

Low-temperature multi-effect distillation (LT-MED) can be used to desalinate and demineralize highly mineralized mine water, facilitating the recycling and reuse of water resources. This study conducted a simulation of LT-MED technology for treating highly mineralized mine water using Aspen Plus and proposed a novel cross-flow optimization scheme. Initially, the impact of operational parameters such as process configuration, number of evaporation effects, and steam input on the gained output ratio (GOR) and scaling risk of a conventional LT-MED system was analyzed. It was found that the number of effects and heating steam flow rate had the most significant influence on GOR, while different processes exhibited limitations regarding GOR and scaling trends. To address these issues, this paper introduced a cross-flow operation process that combined forward, backward, and parallel flow. The simulation results indicated that, under conditions of eight effects, a maximum evaporation temperature of 70 °C, a temperature difference between adjacent effects of 4 °C, and a feed temperature of 45 °C, the cross-flow process—where the feed was introduced from the sixth effect—achieved the highest GOR and significantly reduced scaling risks compared to parallel and backward flow configurations. Finally, to further utilize low-pressure exhaust steam from the final effect of the cross-flow LT-MED system, mechanical vapor compression (MVC) and thermal vapor compression (TVC) were integrated into the LT-MED process. The thermodynamic performance of the coupled system was analyzed, and the simulations demonstrated that the coupled system outperformed the standalone use of either TVC or MVC, with the LT-MED-MVC-TVC system showing superior performance overall. Full article

This study explored the development history and future trends of academic research on electric vehicles (EVs) in a circular economy. We collected 4127 articles on circular economy and EVs from the Web of Science database, and main path analysis indicated that academic research in the field of EVs in a circular economy has covered the following topics in chronological order: EVs as a power resource; vehicle-to-grid (V2G) technology; renewable energy and energy storage grids; smart grid and charging station optimization; and sustainable development of energy, water, and environmental systems. Through cluster analysis and data mining, we identified the following main research topics in the aforementioned field: recycling and reuse of EV batteries, charging stations and energy management, V2G systems and renewable energy, power frequency control systems, dynamic economic emissions, and energy management. Finally, data mining and statistical analysis revealed the following emerging research topics in this field from 2020 to 2023: microgrids, deep learning, loop supply chain, blockchain, and automatic generation control. Various achievements have been attained in research on EVs in a circular economy; however, challenges related to aspects such as sustainable battery recycling charging infrastructure and renewable energy integration remain. Full article

The energy sector is the sector that generates the highest amount of environmental contamination, especially in water sources, mostly in the case of coal-based energy production. The aim of this study was to examine a significant contamination source, heavy metal contamination, in coal mining effluents. The current investigation introduces an MOF platform based on zirconium clusters and isophthalic acid with NH₂-MIP-SO₃H mixed amine and sulfonic acid functional groups in order to remove the most common heavy metal ions in coal mining effluents, including Hg, Cd, Pb, and Cu ions. The water matrix and the operational conditions were identified to be very influential in the removal process, such as the pH of water, the initial metal concentration and operating time. NH₂-MIP-SO₃H offers a great removal efficiency of metals starting from 745.83 mg/g for Cd, 673.67 mg/g for Cu, 589.85 mg/g for Hg, and 481.66 mg/g for Pb ions, with the Langmuir equation for equilibrium and pseudo-second-order equation for kinetics being the ideal models to express the equilibrium and kinetic data, respectively. A significant impact of water pH was found to occur, with the NH₂-MIP-SO₃H platform performing best at pH 6. Reuse of NH₂-MIP-SO₃H demonstrates excellent reusability, sustaining 90% of initial performance over eight regeneration cycles. The interaction of functional group-functional metal was the dominant mechanism in the removal process. The NH₂-MIP-SO₃H unique approach to heavy metal removal provides a very hopeful outlook for additional investigations in larger-scale studies. Full article