Search Results (370)

The rapid expansion of the electrode foil industry has led to the generation of large volumes of acidic wastewater containing strong acids (sulfuric and hydrochloric) and metal ions (such as aluminum and copper). The generated wastewater poses serious environmental challenges, including infrastructure corrosion, soil acidification, and toxicity to aquatic life. This review evaluates three primary treatment approaches: neutralization (adjusting pH and removing metals), ion adsorption (selective recovery of metals and acid recycling), and membrane separation (precision resource recovery). Neutralization is cost-effective for pH adjustment and metal removal but is limited by secondary pollution and low resource recovery. Ion adsorption allows for the targeted recovery of metals and recycling of acid, although it faces challenges related to high costs and scalability. Membrane separation offers accurate separation and resource recovery but is affected by fouling and high energy requirements. Future research should focus on integrated treatment strategies, AI-driven process optimization, and the development of advanced materials to enhance sustainable wastewater management. These efforts aim to provide a scientific basis and technical reference for wastewater treatment in the electrode foil industry. Full article

The comprehensive utilization of hazardous waste may introduce heavy metals, organic pollutants, etc., into products, resulting in secondary pollution. The environmental risk assessment method for hazardous waste resource utilization products is an important technical means of environmental management. We have established a standardized method for hazard identification, exposure evaluation and risk characterization. This study selects waste sulfuric acid generated in the integrated circuit industry as the object and investigates the use of waste sulfuric acid to react with aluminum hydroxide to produce liquid aluminum sulfate flocculant, as well as the environmental risks brought to practitioners and the potential relevant population in the sewage treatment process. By analyzing sulfuric acid and aluminum hydroxide, toxic substances such as nitrate ions, fluorides, As, Pb, Cr, Hg, Cd, etc., were identified. Through exposure scenario analysis, the exposure levels of occupational and non-occupational populations were determined. Based on the dose–response relationship data in the IRIS database of the United States and the carcinogenic and non-carcinogenic data of skin contact routes, it was suggested that chromium and its compounds were the main contributors to carcinogenic risk, and cadmium, its compounds, and mercuric chloride were the contributors to the non-carcinogenic risk. The total carcinogenic risk to human health in occupational populations was 5.31 × 10⁻⁵, and the total non-carcinogenic risk was 8.80 × 10⁻¹. The total carcinogenic risk to human health in non-occupational populations was 1.73 × 10⁻¹⁵, and the total non-carcinogenic risk was 1.23 × 10⁻¹¹. Based on this research, it is clear that the production of liquid aluminum sulfate flocculants from waste sulfuric acid generated in the integrated circuit industry has a low impact on occupational and other populations during use, and the environmental risks generated by this product are acceptable even under the most dangerous conditions. Full article

Aluminum (Al) is involved in almost all aspects of abiotic stress and is supposed to play a crucial role in tea quality. Both exogenous Al and silicon (Si) influence Al uptake, translocation, and accumulation in considerable quantify plants. However, the relationship between Si-mediated Al uptake and tea quality has not been systematically investigated. In this study, we found that Si supply affected caffeine, free amino acids, and Al in young leaves and tea infusion. Si increased the Al content in secondary roots, but it also decreased the ratio of young leaves to secondary roots, with this decreasing ratio becoming more pronounced at higher Al supply levels. Furthermore, Si reduced the Al absorption rate at a constant pH and down-regulated the value of the Michaelis constant (Km). These analyses demonstrate that Si regulates the Al absorption rate and distribution in tea plants—that is, the ratio of Al content in young tea leaves to that in the secondary roots, thereby influencing the concentrations of caffeine, free amino acid, and Al solubility in tea infusions. Full article

Aluminum nitride (AlN), diamond, and β-phase gallium oxide (β-Ga₂O₃) belong to the family of ultra-wide bandgap (UWBG) semiconductors and exhibit remarkable properties for future power and optoelectronic applications. Compared to conventional wide bandgap (WBG) materials such as silicon carbide (SiC) and gallium nitride (GaN), they demonstrate clear advantages in terms of high-voltage, high-temperature, and high-frequency operation, as well as extremely high breakdown fields. In this work, numerical simulations are performed to evaluate and compare the radiative responses of AlN, diamond, and β-Ga₂O₃ when exposed to neutron irradiation covering the full atmospheric spectrum at sea level, from 1 meV to 10 GeV. The Geant4 simulation framework is used to model neutron interactions with the three materials, focusing on single-particle events that may be triggered. A detailed comparison is conducted, particularly concerning the generation of secondary charged particles and their distributions in energy, linear energy transfer (LET), and range given by SRIM. The contribution of the ¹⁴N(n,p)¹⁴C reaction in AlN is also specifically investigated. In addition, the study examines the consequences of these interactions in terms of electron-hole pair generation and charge deposition, and discusses the implications for the radiation sensitivity of these materials when exposed to atmospheric neutrons. Full article

In recent years, research in the field of the sustainable production of refractory ceramics has become topical. Significant attention has been paid to the use of secondary raw materials for obtaining high-quality materials. The purpose of the current study was to develop new high-temperature porous materials based on the magnesium sulfate-refractory clay–chamotte–aluminum system using environmentally friendly raw components. To synthesize porous refractories, rice husk and the by-products of its thermal processing were used as substitutes for ingredients usually introduced into the composition of high-temperature materials. Ground rice husk was used as both a burnout additive and a silica source. It was added to the mixture instead of chamotte. An organic condensate from rice husk pyrolysis was used as a binder. A sodium silicate solution, after activating pyrolyzed rice husk with alkali, was also tested as a binder. These liquid ingredients served as replacements for lignosulfonate and liquid glass. The new raw material components and the porous refractories obtained with their use were studied using methods of chemical analysis, XRD, GC-MS, TA, SEM, and EDS. Standard methods for studying the properties of refractories were used to evaluate the physicomechanical and thermal characteristics of the experimental materials. The sample with the maximum content of rice husk (14.4 wt.%) and organic condensate from its pyrolysis (10.5 wt.%) demonstrated promising properties as a light porous refractory: an apparent porosity of 44%, a volumetric weight of 1.1 g·cm⁻³, compressive strength of 2.1 MPa, tensile strength in bending of 4.5 MPa, bond strength of 0.01 MPa, thermal shock resistance of 155 thermal cycles, and thermal conductivity of 0.05 W (m·K)⁻¹. It can be used as a prospective thermal insulating material. Full article

This article aims to improve the real-time monitoring accuracy of the loss rate for grain combine harvesters by optimizing the sensor-sensitive plate structure, thereby addressing the problem of low detection efficiency in existing equipment. Based on Kirchhoff’s thin plate theory, COMSOL 6.0 software was utilized to conduct modal analysis and single-grain impact tests on rectangular and circular sensing plates fabricated from three materials: stainless steel, aluminum alloy, and cupronickel. The circular stainless steel sensing plate was identified as the optimal structure, whose natural frequency and sensitivity significantly outperform those of traditional rectangular plates. By integrating a signal processing strategy based on FFT (Fast Fourier Transform) spectrum analysis (band-pass filtering: 1.0~3.0 kHz, voltage threshold: 3.5 V) and a high-level duration counting algorithm, the system effectively distinguishes between grains and impurities and resolves the counting errors caused by multi-grain impacts and secondary rebounds. Field experiments demonstrate that the developed sensor exhibits strong anti-interference ability and high measurement accuracy, providing reliable technical support for reducing harvesting losses. Full article

Reinforced alumina ceramics are renowned for their high hardness and strength among common oxide ceramics. However, high-temperature or high-pressure treatment is necessary for maximizing values of strength and hardness. In this paper, liquid-phase-assisted pressureless sintering of alumina reinforced with zirconia was studied. Sintering of dense ceramic bodies in relatively low temperatures (up to 1100 °C) was possible with the usage of CuO-TiO₂-Nb₂O₅-based additive, together with an intense milling process. By using the XRD method, the formation of dominant α-Al₂O₃ and m-ZrO₂ phases with small concentrations of secondary ones in experimental samples was confirmed. SEM studies showed that uniform distribution of components in the composite was achieved in samples sintered from intensively milled powders. The significant increase in the values of Vickers hardness and biaxial flexural strength (by 2.6 times) in samples from intensively milled powders at a sintering temperature of 1050 °C was explained by reduced porosity, improved grain distribution, and the formation of the t-ZrO₂ phase in the alumina-reinforced composite. The study clearly showed high potential of the proposed low-temperature sintering method for zirconia-toughened aluminum oxide, which can be used in manufacturing of advanced ceramics. Full article

To conserve natural resources and reduce waste generation, the effective valorization of industrial waste and byproducts in engineering applications is becoming increasingly important. Among these materials, aluminum production residues (APRs) offer a promising and sustainable solution for road pavement applications. Unlike previous reviews, this paper uniquely examines recent research on the use of various APRs in bituminous materials across multiple scales, with particular attention to their roles as additives and fillers. The APRs examined included red mud (RM), aluminum dross (AD), and spent pot lining (SPL) residues, as well as secondary aluminum waste (SAW). These materials have been employed as additives in asphalt binders (microscale), as fillers in asphalt mastics (mesoscale), and as additives or fillers in asphalt mixtures (macroscale). Overall, this review indicates that adopting appropriate treatment approaches for APRs as asphalt modifiers can enhance their dispersion, thermal stability, rheological behavior, and leaching performance. In particular, the use of RM has been shown to improve thermal stability, tensile strength, intermediate-temperature cracking resistance, and rutting resistance, largely due to the increased stiffness it imparts to asphalt mastic and mixture phases. However, there is no clear consensus among researchers regarding other properties, as performance outcomes depend strongly on multiple factors, particularly the physicochemical characteristics of the RM, filler–binder ratios, testing methods, and reference filler types. Other APRs—such as AD, SPL, and SAW—have also shown beneficial effects on the performance of asphalt mixtures. There is still limited research on the influence of APRs physicochemical variability on asphalt–filler interactions and the performance of bituminous materials. For the safe and large-scale adoption of APRs, it is essential to establish standardized characterization procedures, testing methods, and application guidelines while considering diverse climatic conditions. Comprehensive assessments of cost and environmental impacts should also be incorporated to support informed decision-making by engineers and industrial stakeholders. Full article

Aluminum’s unique properties have led to its widespread use across multiple industries, including transportation, aviation, power generation, construction, and food packaging. In recent years, global aluminum consumption has risen significantly, with China experiencing particularly sharp growth in both production and demand. In Russia, the aluminum industry is dominated by UC RUSAL, which consolidates all Russian aluminum and alumina production facilities, along with several international operations and mining assets. Despite its global presence, the company remains heavily reliant on imported raw materials (approximately 50%) for alumina production, resulting in reduced operational efficiency and declining output. This dependency has necessitated the exploration of strategies to diversify raw material sources across different stages of the aluminum production value chain. This study identifies and classifies key diversification options for global aluminum companies, focusing on secondary aluminum production, primary aluminum production, and alumina extraction from mined minerals, industrial waste, and by-products. The options were evaluated based on predefined criteria (feasibility, cost per Mg of alumina, logistics, alumina output, and economic security), and two options were selected. The research substantiates the feasibility of diversifying production through nepheline utilization. For the medium term, an economic efficiency assessment was conducted for a proposed 30% capacity expansion at the Pikalevo Alumina Refinery. Additionally, long-term opportunities for increasing aluminum output were identified, including leveraging foreign assets while accounting for associated risks. Full article

Ladle slag (LF slag) is a by-product of secondary steelmaking that presents unique valorization challenges compared to BOF or EAF slags due to its distinctive chemical composition (high Al₂O₃ and CaO content) and uncontrolled hydraulic activity. While other steelmaking slags can be reused as supplementary cementitious materials or aggregates, LF slag is predominantly landfilled, with over 2 million tons discarded annually in Europe alone. This study introduces a novel pyrometallurgical valorization strategy that, unlike conventional approaches focused solely on mineral recovery, simultaneously recovers both metallic and mineral value through aluminothermic reduction. This process utilizes end-of-waste aluminum scrap rather than virgin materials to reduce Fe and Si oxides, creating a circular economy solution that addresses two waste streams simultaneously. The process generates two valuable products with low liquidus temperatures: a ferrosilicon alloy (FeSi15-50 grade) and a residual oxide rich in calcium and magnesium aluminates suitable for cementitious or ceramic applications. Through the integration of FactSage thermodynamic simulations with experimental validation, it is possible to predict and control phase evolution during equilibrium cooling, an approach not previously applied to LF slag valorization. Experimental validation using industrial slags confirms the theoretical predictions and demonstrates the process operates in a near-energy-neutral, self-sustaining mode by recovering both chemical and sensible thermal energy (50–100 kWh per ton of slag). This represents approximately 90% lower energy consumption compared to conventional ferrosilicon production. The work provides a comprehensive and scalable approach to transform a problematic waste material into valuable products, supporting circular economy principles and low-carbon metallurgy objectives. Full article

This study examines the microstructure and properties of 7A36 aluminum alloys processed through low-frequency electromagnetic casting (LFEC) with microalloyed Sc. Following secondary hot deformation, the addition of Sc refined the average grain size from 3.8 μm to 0.9 μm and reduced the deformed texture content. In the T6-aged condition, the combined application of Sc and LFEC enhanced the hardness (234 HV to 238 HV), ultimate tensile strength (647 MPa to 693 MPa), and elongation (EL). Fractographic analysis revealed brittle fracture modes dominated by cleavage, with minor intergranular contributions. The corrosion resistance was poorest in the rolled state and superior in the two-stage-aged state. Under two-stage aging, the maximum corrosion depth for the Sc-modified, LFEC-processed alloy decreased from 113.6 to 49.1 μm. The synergistic integration of Sc alloying and LFEC significantly improved both the mechanical properties and corrosion resistance. Full article

Wire Arc Additive Manufacturing (WAAM) offers high deposition rates and cost-effective production of large metal components but suffers from poor surface quality, particularly surface waviness, which increases post-processing requirements and limits industrial adoption. Since waviness directly impacts structural integrity, resource efficiency, and industrial applicability, understanding how process parameters govern this feature is critical for reducing post-processing requirement. This study systematically investigated the influence of voltage, travel speed, and wire feed speed on surface waviness in aluminum alloy walls fabricated by WAAM. A two-level factorial design with 16 experiments was conducted, and surface waviness was quantified using height gauge measurements relative to the expected bead height. Statistical analyses, including ANOVA and multiple linear regression, were applied to evaluate parameter significance. The results revealed that wire feed speed was the most influential parameter, showing a strong positive correlation with waviness due to excess material deposition. Voltage exhibited a weaker, stabilizing effect, with higher values marginally reducing waviness through improved arc stability, while travel speed had negligible influence within the studied range. The regression model achieved an $R^2$ 0.389, with validation tests indicating reasonable predictive accuracy. These findings demonstrate that controlling wire feed speed is critical for minimizing waviness, while higher voltage may serve as a secondary stabilizing factor. The study was limited to surface waviness; however, future work should consider the role of thermal accumulation, inter-pass temperature, and external disturbances on surface stability. Such insights could enable adaptive parameter control strategies to further reduce post-processing needs and enhance the industrial viability of WAAM. Full article

Antimicrobial resistance poses a growing threat to public health, and integrated surveillance strategies across environmental compartments such as treated wastewater and biosolids can substantially improve monitoring efforts. A key challenge is the diversity of available protocols, which complicates comparability for the concentration and detection of antibiotic resistance genes (ARGs), particularly in complex matrices. In this study, we compared two commonly used concentration methods—filtration–centrifugation (FC) and aluminum-based precipitation (AP)—and two detection techniques, quantitative PCR (qPCR) and droplet digital PCR (ddPCR), for the quantification of four clinically relevant ARGs: tet(A), bla_CTX-M group 1, qnrB, and catI. Analyses were performed in both secondary treated wastewater and biosolid samples, including their purified bacteriophage-associated DNA fractions. Results showed that the AP method provided higher ARG concentrations than FC, particularly in wastewater samples. ddPCR demonstrated greater sensitivity than qPCR in wastewater, whereas in biosolids, both methods performed similarly, although ddPCR yielded weaker detection. Importantly, ARGs were detected in the phage fraction of both matrices, with ddPCR generally offering higher detection levels. These results provide comparative insights into established methodologies and highlight the value of selecting appropriate protocols based on matrix characteristics and surveillance objectives. Full article

Al-Zn-Mg-Cu alloys are widely used as heat-treatable ultra-high-strength materials in aerospace structural applications. While conventional single-stage aging enables high strength, advanced performance demands call for precise microstructural control via multi-stage aging. In this study, we employ a combination of scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) to investigate the microstructural evolution and its correlation with mechanical properties of AA7150 aluminum alloy subjected to two-step aging treatments, following a 6 h pre-aging at 120 °C. Through atomic-scale STEM imaging along the [110]_Al zone axis, we systematically characterize the precipitation behavior of GPII zones, η′ phases, and equilibrium η phases both within the grains and at grain boundaries under varying secondary aging (SA) conditions. Our results reveal that increasing the SA temperature from 140 °C to 180 °C leads to coarsening and reduced number density of intragranular precipitates, while promoting the continuous and coarse precipitation of η phases along grain boundaries, accompanied by a widening of the precipitation-free zone (PFZ). Notably, SA at 160 °C induces the formation of fine, uniformly dispersed nanoscale η′ precipitates in the alloy, as confirmed by XRD phase analysis. Aging at this temperature markedly enhances the mechanical properties, achieving an ultimate tensile strength (UTS) of 613 MPa and a yield strength (YS) of 598 MPa, while presenting an exceptionally broad peak-aging plateau. Owing to this feature, a moderate extension of the SA duration does not reduce strength and can further improve ductility, increasing the elongation (EL) to 14.26%. These results demonstrate a novel two-step heat-treatment strategy that simultaneously achieves ultra-high strength and excellent ductility, highlighting the critical role of advanced electron microscopy in elucidating phase-transformation pathways that inform microstructure-guided alloy design and processing. Full article

This study addresses the challenge of simultaneously improving the electrical conductivity and strength of aluminum alloys. We innovatively combine powder metallurgy with melt stirring casting to fabricate graphite flake-added aluminum matrix composites through secondary remelting, electromagnetic stirring, and extruding. The influence of graphite flake content gradient (0–3.0 wt.%) on the mechanical properties and electrical conductivity was systematically investigated. Our results demonstrate that the composite with 0.2 wt.% graphite flakes (sample GM02) exhibits optimal comprehensive performance: tensile strength reaches 100.9 MPa (a 124% increase over pure Al), and electrical conductivity reaches 67.1% IACS (a 9.6% increase). Microstructural analysis reveals that low-content graphite flakes effectively suppressed electron scattering by forming semi-coherent interfaces. However, when graphite flake content exceeds 0.5 wt.%, a significant decrease in conductivity and plasticity (elongation below 10%) occurs due to increased Al₄C₃ phase formation, enhanced grain boundary scattering caused by grain refinement, and porosity defects induced by graphite flake agglomeration. This study provides a novel approach for the industrial production of high-performance, lightweight conductive components. Full article