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Volume 13
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Processes, Volume 13, Issue 12 (December 2025) – 16 articles

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17 pages, 5089 KB  
Article
Study on the Evolution Law of Four-Dimensional In Situ Stress During Hydraulic Fracturing of Deep Shale Gas Reservoir
by Shuai Cui, Jianfa Wu, Bo Zeng, Haoyong Huang, Shouyi Wang, Houbin Liu and Junchuan Gui
Processes 2025, 13(12), 3772; https://doi.org/10.3390/pr13123772 - 21 Nov 2025
Abstract
The increasing burial depth of deep shale formations in the southern Sichuan leads to more complex in situ stresses and geological structures, which in turn raises the challenges of hydraulic fracturing. Although enlarging the treatment scale and injection rate can enhance reservoir stimulation, [...] Read more.
The increasing burial depth of deep shale formations in the southern Sichuan leads to more complex in situ stresses and geological structures, which in turn raises the challenges of hydraulic fracturing. Although enlarging the treatment scale and injection rate can enhance reservoir stimulation, the intensive development of faults and fractures in deep shale formations aggravates stress instability, inducing casing deformation, fracture communication, and other engineering risks that constrain efficient shale gas production. In this study, a cross-scale geomechanical model linking the regional to near-wellbore domains was constructed. A dynamic evolution equation was established based on flow–stress coupling, and a numerical conversion from the geological model to the finite element model was implemented through self-programming, thereby developing a simulation method for dynamic geomechanical evolution during hydraulic fracturing. Results indicate that dynamic variations in pore pressure dominate stress redistribution, while near-wellbore heterogeneity and mechanical property distribution significantly affect prediction accuracy. The injection of fracturing fluid generates a high-pressure gradient that drives pore pressure diffusion along fracture networks and faults, exhibiting a strong near-wellbore but weak far-field non-steady spatial attenuation. As the pore pressure increases, the peak value reaches 1.4 times the original pressure. The triaxial stress shows a negative correlation and decreases. The horizontal minimum principal stress shows the most significant drop, with a reduction of 15.79% to 20.68%, while the vertical stress changes the least, with a reduction of 5.7% to 7.14%. Compared with the initial stress state, the horizontal stress difference increases during fracturing. Rapid pore-pressure surges and fault distributions further trigger stress reorientation, with the magnitude of rotation positively correlated with the intensity of pore-pressure variation. The high porosity and permeability characteristics of the initial fracture network lead to a rapid attenuation of the stress around the wellbore. In the middle and later stages, as the pressure balance is achieved through fracture filling, the pore pressure rises and the stress decline tends to stabilize. The findings provide significant insights into the dynamic stress evolution of deep shale reservoirs during fracturing and offer theoretical support for optimizing fracturing design and mitigating engineering risks. Full article
(This article belongs to the Section Energy Systems)
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15 pages, 5576 KB  
Article
Role of Shear-Thinning-Induced Viscosity Heterogeneity in Regulating Fingering Transition of CO2 Flooding Within Porous Media
by Wei Shi, Wenjing He, Fengyu Zhao and Long He
Processes 2025, 13(12), 3771; https://doi.org/10.3390/pr13123771 - 21 Nov 2025
Abstract
During the process of CO2 displacing shear-thinning oil, the occurrence of fingering is a key factor contributing to a reduction in both displacement and sequestration efficiency. Existing studies typically use the average viscosity to calculate the viscosity ratio M for shear-thinning oil, [...] Read more.
During the process of CO2 displacing shear-thinning oil, the occurrence of fingering is a key factor contributing to a reduction in both displacement and sequestration efficiency. Existing studies typically use the average viscosity to calculate the viscosity ratio M for shear-thinning oil, overlooking the non-uniform viscosity distribution resulting from uneven shear stress. Consequently, a phase diagram based on M fails to accurately capture the underlying mechanism influencing fingering. We investigate the influence of shear-thinning on fingering patterns by analyzing viscosity heterogeneity during immiscible CO2 flooding in porous media. The results showed the following: (1) An increase in zero-shear viscosity (μ0) resulted in a greater viscosity difference between the two phases, which intensified interface instability, and the power-law index (n) diminished the shear-thinning effect, promoted fingering formation, and significantly reduced displacement efficiency, with a maximum reduction of 28.6% observed in this study. (2) Shear-thinning oil was more prone to capillary fingering compared to Newtonian oil under the same capillary number Ca and viscosity ratio M. (3) Intense pressure fluctuations at the displacement front combined with non-uniform viscosity distribution exacerbate interfacial instability and make shear-thinning oil more prone to capillary fingering. This study provides guidance for optimizing displacement strategies for shear-thinning fluids and advancing the practical implementation of CO2 flooding technology. Full article
(This article belongs to the Section Chemical Processes and Systems)
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18 pages, 1829 KB  
Article
A Coordinated Control Strategy for Black Start of Wind Diesel Storage Microgrid Considering SOC Balance of Energy Storage
by Ming Zhou, Weiqing Wang, Xiaozhu Li, Pei Li and Yinghui Chen
Processes 2025, 13(12), 3770; https://doi.org/10.3390/pr13123770 - 21 Nov 2025
Abstract
The “double-high” characteristics of power systems—namely, the high penetration of renewable energy and the widespread use of power electronic devices—have significantly increased operational complexity. This underscores the necessity of adopting coordinated energy storage systems and wind-storage hybrid microgrids to support the black start [...] Read more.
The “double-high” characteristics of power systems—namely, the high penetration of renewable energy and the widespread use of power electronic devices—have significantly increased operational complexity. This underscores the necessity of adopting coordinated energy storage systems and wind-storage hybrid microgrids to support the black start restoration of thermal power plants. This paper addresses two critical challenges in the black start process of a wind–storage–diesel microgrid: dynamic power coordination and state of charge (SOC) balancing of the energy storage system. A coordinated control strategy is proposed for the entire black start sequence, incorporating SOC equilibrium management. A novel hybrid control architecture is introduced, which effectively integrates grid-forming virtual synchronous generator (VSG)-based energy storage units with grid-following P/Q-controlled storage units, while leveraging the dynamic reactive power support capability of diesel generators. By coordinating SOC balancing among storage units and combining diesel generation with wind power maximum power point tracking (MPPT) control, the strategy enables wind power output to effectively track microgrid load demand. It also ensures reliable reactive power support to prevent black start failure. During periods of power imbalance between wind generation and black start loads, the energy storage system compensates for active power discrepancies. Furthermore, control schemes for both grid-forming and grid-following storage units are enhanced to achieve SOC-based active power distribution, ensuring balanced SOC levels across all units. Finally, a simulation model for the wind–storage–diesel black start is developed in PSCAD/EMTDC, validating the effectiveness and robustness of the proposed control strategy. Full article
(This article belongs to the Section Energy Systems)
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18 pages, 3396 KB  
Article
Distribution Model of Wellbore Collapse Pressure in Deviated Wells Considering Fracture Development and Engineering Applications
by Lu Li, Yang Zhao, Yafei Fu and Ping Yue
Processes 2025, 13(12), 3769; https://doi.org/10.3390/pr13123769 - 21 Nov 2025
Abstract
During drilling in fractured formations, wellbore instability issues such as fluid loss and collapse frequently occur, severely compromising drilling safety. Traditional criteria such as Mohr–Coulomb often fail to adequately account for fracture effects, leading to inaccurate collapse pressure predictions. Taking the Tahe Oilfield [...] Read more.
During drilling in fractured formations, wellbore instability issues such as fluid loss and collapse frequently occur, severely compromising drilling safety. Traditional criteria such as Mohr–Coulomb often fail to adequately account for fracture effects, leading to inaccurate collapse pressure predictions. Taking the Tahe Oilfield as a case study, this research develops an enhanced model for predicting wellbore collapse pressure in fractured formations. Based on principles of elastic mechanics and Biot’s effective stress theory, a stress distribution model around deviated wellbores is established. The single weak plane strength criterion is integrated with the Mohr–Coulomb criterion to characterize failure mechanisms in both fractured zones and intact rock matrix. Newton’s iterative method, implemented in MATLAB, is employed to solve for collapse pressure, and a sensitivity analysis is conducted to evaluate the influence of factors such as in situ stresses and fracture orientation. A case study from Well THX demonstrates that neglecting fractures results in a symmetrical collapse pressure profile and an unduly narrow safe mud weight window. In contrast, accounting for fractures significantly increases the required mud weight and identifies an optimal azimuth range for enhancing wellbore stability. The Mohr–Coulomb criterion is shown to underestimate the necessary mud weight, which aligns with actual wellbore collapse incidents encountered during drilling. The single weak plane criterion offers more accurate predictions, recommending a higher minimum mud density and an optimized well trajectory to mitigate drilling risks. These findings offer theoretical and practical guidance for mitigating wellbore instability in fractured formations. Full article
(This article belongs to the Topic Petroleum and Gas Engineering, 2nd edition)
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28 pages, 8498 KB  
Article
Characteristics of Grouting-Induced Microfractures in Fractured Rock Masses: Numerical Simulation, Microseismic Monitoring, and Laboratory Tests
by Qiukai Gai, Lei Huang, Shiqi Liu, Qiang Fu, Xiaoding Xu, Jia Wang, Xingxing Zhang, Chao Chen and Chuanjiu Zhang
Processes 2025, 13(12), 3768; https://doi.org/10.3390/pr13123768 - 21 Nov 2025
Abstract
In deep mining engineering, grouting operations, although designed for reinforcement, inevitably induce microfracturing and associated microseismicity. Investigating the characteristics of grouting-induced microfractures in fractured rock masses is crucial for evaluating the grouting process and its effectiveness. Using the Wutongzhuang Mine as a case [...] Read more.
In deep mining engineering, grouting operations, although designed for reinforcement, inevitably induce microfracturing and associated microseismicity. Investigating the characteristics of grouting-induced microfractures in fractured rock masses is crucial for evaluating the grouting process and its effectiveness. Using the Wutongzhuang Mine as a case study, this paper first establishes mechanical criteria covering three stages—fracture filling, coupled permeation, and fracturing propagation—to analyze the process characteristics of grouting-induced microfractures. It reveals the mechanisms by which grouting pressure, in situ stress, and rock mass strength control fracture initiation and propagation. Furthermore, a grouting simulation method based on the Particle Flow Code (PFC) is proposed and summarized, constructing a “pipe-domain” fluid network considering fluid–solid coupling, thereby achieving a refined numerical reproduction of the entire grouting process. Addressing the complex geological conditions of the mine, three typical grouting modes are simulated and analyzed: grouting under conventional geological conditions, grouting under densely fractured conditions, and grouting near fault structures. The simulation results unveil their core influencing factors and behavioral characteristics: under conventional conditions, microfractures exhibit a “three-stage” evolution with the grouting process; under densely fractured conditions, the density of pre-existing fractures dominates the formation of complex fracture networks; and finally, fault structures guide fracture propagation, causing microfractures to cluster nearby. Subsequently, the development trends of microfractures under different grouting effects are clarified: after effective reinforcement, the rock mass strength increases, and the scope and quantity of fractures induced by subsequent grouting significantly decrease. The behavioral patterns under these different grouting modes are effectively validated through field microseismic monitoring, confirming the intrinsic relationship between the spatio-temporal evolution of grouting-induced microfractures and geological structures/grouting techniques. Finally, laboratory tests are conducted using a self-developed experimental apparatus, selecting grouting pressure, pore water pressure in the rock mass, and matrix grain size as variables. The mapping relationships between these variables and microseismic waveform characteristics, amplitude, etc., under different schemes are obtained, providing a basis for inverting the microfracturing process and evaluating grouting effectiveness. The research results provide multi-faceted references for characterizing the stability of fractured rock masses via microseismic monitoring and for optimizing grouting effectiveness. Full article
(This article belongs to the Special Issue Advanced Processes in Mining Safety and Disaster Prevention: From Gas Extraction to Fire/Dust Control)
6 pages, 230 KB  
Editorial
Special Issue on “Simulation, Modeling, and Decision-Making Processes in Manufacturing Systems and Industrial Engineering”
by Van Thanh Phan, Chia Nan Wang, Hector Tibo and Nhat Luong Nhieu
Processes 2025, 13(12), 3767; https://doi.org/10.3390/pr13123767 - 21 Nov 2025
Abstract
The rapid evolution of emerging technologies, the globalization of industrial networks, and the increasing complexity of production ecosystems have fundamentally reshaped the paradigm of modern manufacturing and industrial engineering [...] Full article
(This article belongs to the Special Issue Simulation, Modeling, and Decision-Making Processes in Manufacturing Systems and Industrial Engineering)
28 pages, 754 KB  
Review
Multi-Area Economic Dispatch Under Renewable Integration: Optimization Challenges and Research Perspectives
by Hossein Lotfi
Processes 2025, 13(12), 3766; https://doi.org/10.3390/pr13123766 - 21 Nov 2025
Abstract
The shift toward decentralized energy systems and the rapid growth of renewable integration have brought renewed attention to the Multi-Area Economic Dispatch (MAED) problem. Unlike single-area dispatch, which focuses only on local balance, MAED must also coordinate inter-area exchanges, respect regional operating limits, [...] Read more.
The shift toward decentralized energy systems and the rapid growth of renewable integration have brought renewed attention to the Multi-Area Economic Dispatch (MAED) problem. Unlike single-area dispatch, which focuses only on local balance, MAED must also coordinate inter-area exchanges, respect regional operating limits, and ensure overall reliability. This paper reviews both MAED and its dynamic extension, the Multi-Area Dynamic Economic Dispatch (MADED). The review examines core objectives—cost minimization, emission reduction, and renewable utilization—and surveys a wide range of solution methods. These include classical mathematical programming, metaheuristic and hybrid approaches, and more recent advances based on machine learning and reinforcement learning. Special emphasis is placed on uncertainty-oriented models that address demand variability, market dynamics, and renewable fluctuations. The discussion also highlights the role of Distributed Energy Resources (DERs), Energy Storage Systems (ESSs), and Demand Response (DR) in improving system flexibility and resilience. Despite notable progress, research gaps remain, including limited treatment of uncertainty, insufficient integration of DR, oversimplified modeling of electric vehicles, and the marginal role of reliability. To address these issues, a research agenda is proposed that aims to develop more adaptive, scalable, and sustainable dispatch models. The insights provided are intended to support both academic research and practical applications in the planning and operation of interconnected grids. Full article
(This article belongs to the Special Issue Modeling, Optimization, and Control of Distributed Energy Systems)
18 pages, 1313 KB  
Article
Analysis of Flow Characteristics and Structural Optimization of High-Strength Cooling Equipment for Hot-Rolled Strip Steel
by Jianhui Shi, Jian Wang, Kaiyuan Zhang, Xuemei Sun and Chuntian Xu
Processes 2025, 13(12), 3765; https://doi.org/10.3390/pr13123765 - 21 Nov 2025
Abstract
High-strength cooling collectors are the key equipment for post-roll cooling technology of hot-rolled plates, and the internal flow characteristics of the collector are crucial to the quality and efficiency of cooling. In this work, numerical simulation is used to study the collector w [...] Read more.
High-strength cooling collectors are the key equipment for post-roll cooling technology of hot-rolled plates, and the internal flow characteristics of the collector are crucial to the quality and efficiency of cooling. In this work, numerical simulation is used to study the collector w2 (collector width), β (manifold inclination), and h2 (slot height) in different process parameters at the outlet of the velocity size and uniformity of the influence of the law. By comparing the two methods of steady state and transient state, the average velocity and flux errors are less than 0.1, and the effects of structural modifications on the outlet flow velocity and flow field uniformity were obtained for two sizes of trough nozzles. The results show that the increase in pressure increases the fluctuation in velocity, but the increase in velocity in the center of the slot outlet keeps decreasing; when the height of the tank h1 = 90 mm, the increase in β causes the velocity of the slot outlet to decrease, but the fluctuation in velocity increases; when h2 increases, the fluctuation in the velocity in the center of the slit outlet is obviously reduced, and the fluctuation is reduced most significantly when it is increased to 9 mm, but it will result in the decrease in the average value of the outlet velocity. Therefore, within the scope of this study, the optimal process parameters are inlet pressure 0.5 -0.6 MPa, β = 10°, h2 = 9 -15 mm, and w2 = 100 -110 mm. Full article
(This article belongs to the Section Materials Processes)
20 pages, 1662 KB  
Review
Recent Advances in the Application of Artificial Intelligence in Microalgal Cultivation
by Vijay Rayamajhi, Mudasir Hussain, Hyunwoung Shin and Sangmok Jung
Processes 2025, 13(12), 3764; https://doi.org/10.3390/pr13123764 - 21 Nov 2025
Abstract
Microalgae are unicellular, industrially important organisms that are used extensively in a range of industrial, environmental, and biorefinery applications. They can produce lipids, carbohydrates, and possibly additional vital bioactive substances. The increasing popularity of artificial intelligence (AI) in microalgae research can be attributed [...] Read more.
Microalgae are unicellular, industrially important organisms that are used extensively in a range of industrial, environmental, and biorefinery applications. They can produce lipids, carbohydrates, and possibly additional vital bioactive substances. The increasing popularity of artificial intelligence (AI) in microalgae research can be attributed to its algorithms’ ability to manage the complexity of unexpected biosystems. In the case of microalgae-based biorefineries, AI technology can also help uncover system dynamics and uncertainties, provide helpful predictive analytics, and expedite the optimisation process. AI is used in microalgal cultivation to optimise carbon capture, biomass production, and conditions for growth. Additionally, it is employed for genome editing, automated monitoring, and lipid accumulation enhancement. However, its uses are broad and constantly growing. Furthermore, critical environmental parameters in microalgae culture, including temperature, light intensity, pH, dissolved oxygen, and nutrient levels, may be continually monitored and controlled by internet of things (IoT)-based devices. This review comprehensively summarises the latest applications of AI technology in the field of microalgae cultivation and the role of IoT-based automatic control. Full article
(This article belongs to the Section AI-Enabled Process Engineering)
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23 pages, 1439 KB  
Article
Natural Carboxylic Acid Deep Eutectic Solvents: Properties, Bioactivities and Walnut Green Peel Flavonoid Extraction
by Lei Gong, Lili Yue, Menghao Li, Qilong Chen, Xuan Liu, Daming Gao, Junli Ren, Nan Zhang and Jie Zhu
Processes 2025, 13(12), 3763; https://doi.org/10.3390/pr13123763 - 21 Nov 2025
Abstract
Novel green solvents are a key focus in green chemistry, and deep eutectic solvents (DESs) are promising sustainable solvents. This study systematically examined the physicochemical properties (water content, polarity, conductivity, Kamlet-Taft parameters, and viscosity) of ten carboxylic acid-based DESs (CADESs). It also evaluated [...] Read more.
Novel green solvents are a key focus in green chemistry, and deep eutectic solvents (DESs) are promising sustainable solvents. This study systematically examined the physicochemical properties (water content, polarity, conductivity, Kamlet-Taft parameters, and viscosity) of ten carboxylic acid-based DESs (CADESs). It also evaluated their antibacterial activity against representative Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The antibacterial activity of CADESs is closely related to low pH values, hydrogen bond donor properties, and the destructive effect on bacterial cell membranes. antioxidant properties via ABTS, DPPH scavenging assays and Fe2+ chelating assays, and phytotoxicity through mung bean tests. When used to extract flavonoids from walnut peel, the choline chloride/levulinic acid system with 30% water achieved the highest yield of 112.8 mg RE·g−1 DW. Therefore, CADESs show great potential as green solvents for flavonoid extraction in sustainable technologies. Full article
(This article belongs to the Section Chemical Processes and Systems)
27 pages, 6058 KB  
Article
A Dynamic Energy Management Algorithm for Battery–Ultracapacitor-Based UPS Systems
by Yagmur Kircicek and Hakan Akca
Processes 2025, 13(12), 3762; https://doi.org/10.3390/pr13123762 - 21 Nov 2025
Abstract
This study presents a dynamic energy management algorithm (DEMA) designed for hybrid battery–ultracapacitor systems in uninterruptible power supply (UPS) applications. The proposed algorithm aims to enhance power reliability and extend battery life by dynamically coordinating energy flow between the battery and ultracapacitor under [...] Read more.
This study presents a dynamic energy management algorithm (DEMA) designed for hybrid battery–ultracapacitor systems in uninterruptible power supply (UPS) applications. The proposed algorithm aims to enhance power reliability and extend battery life by dynamically coordinating energy flow between the battery and ultracapacitor under various operating modes. A single-phase UPS system was modeled and simulated in MATLAB/Simulink (Matlab R2025a version), and subsequently validated through experimental tests using an energy analyzer and an oscilloscope. The DEMA identifies and manages five operating modes, ensuring smooth transitions between grid-connected and backup states. During sudden load variations, particularly at a 1500 W step change, the ultracapacitor effectively supports the battery by supplying transient power, thereby reducing current stress and preventing deep discharge. Both simulation and experimental results confirm that the proposed algorithm maintains stable DC bus voltage, improves dynamic response, and achieves optimal energy utilization across all modes. The developed hybrid UPS control approach demonstrates high reliability and can be effectively implemented in critical load systems requiring uninterrupted power and enhanced battery longevity. Full article
(This article belongs to the Special Issue Advanced Processes for Sustainable Energy Conversion and Utilization)
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26 pages, 2963 KB  
Review
Valorization of Pistachio Green Hull: Advances in Extraction and Characterization of Phenolic Compounds
by Andrés Javier Ordoñez-Cano, Ulises Ramírez-Esparza, Mónica Alvarado-González, Ramiro Baeza-Jiménez, José Carlos Espinoza-Hicks, Lilia Arely Prado-Barragán and José Juan Buenrostro-Figueroa
Processes 2025, 13(12), 3761; https://doi.org/10.3390/pr13123761 - 21 Nov 2025
Abstract
Substantial agro-industrial waste is generated by the food industry, including pistachio green hulls (PGH), which can constitute 40% to 60% of the fresh fruit weight. This by-product contains bioactive functional components, especially phenolic compounds (PCs). An overview of research focused on PCs extracted [...] Read more.
Substantial agro-industrial waste is generated by the food industry, including pistachio green hulls (PGH), which can constitute 40% to 60% of the fresh fruit weight. This by-product contains bioactive functional components, especially phenolic compounds (PCs). An overview of research focused on PCs extracted from PGH is presented, highlighting their chemical composition, extraction methods, compound identification, and antioxidant and antibacterial activities. Extraction techniques such as ultrasound, microwave-assisted extraction, and solid-state fermentation are utilized, with mild organic solvents like water, ethanol, methanol, or their mixtures employed. The quantification of PCs is commonly performed using the Folin–Ciocalteu assay, HCl-Butanol technique, and aluminum chloride colorimetric assays. Furthermore, identification of compounds is generally accomplished through high-performance liquid chromatography (HPLC) or gas chromatography (GC), often coupled with mass spectrometry or photodiode-array detectors to enhance accuracy and reliability. Gallic acid, kaempferol, quercetin, cyanidin, and catechin are the main PCs identified, with their antioxidant activity validated by ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric-reducing antioxidant power) assays. Antibacterial effectiveness has been demonstrated against bacteria using disk diffusion and minimum inhibitory concentration methods. These findings indicate potential uses of PGH by-products in the food, cosmetic, and pharmaceutical industries, contributing to a circular economy and enhancing agro-industrial waste management. Full article
(This article belongs to the Special Issue Natural Bioactive Compounds: Methods for Extraction, Characterization and Application)
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21 pages, 7882 KB  
Article
Unlocking Refractory Gold: Synergistic Pretreatment Strategies for High-Efficiency Thiosulfate Leaching
by Sepideh Javanshir, Lena Sundqvist Öqvist, Ida Strandkvist and Fredrik Engström
Processes 2025, 13(12), 3760; https://doi.org/10.3390/pr13123760 - 21 Nov 2025
Abstract
This study evaluates four physicochemical pretreatments—ultra-fine grinding, roasting, alkaline pressure oxidation (POX), and oxidative ammoniacal pre-leaching—for improving gold extraction from a refractory sulfide concentrate produced trough flotation. The gold extraction by direct cyanidation is only ~48.6%, mainly due to the encapsulation of gold [...] Read more.
This study evaluates four physicochemical pretreatments—ultra-fine grinding, roasting, alkaline pressure oxidation (POX), and oxidative ammoniacal pre-leaching—for improving gold extraction from a refractory sulfide concentrate produced trough flotation. The gold extraction by direct cyanidation is only ~48.6%, mainly due to the encapsulation of gold by associated minerals. Ultra-fine grinding increased the BET surface area eight-fold but depressed gold dissolution from 74% to 18% due to accelerated thiosulfate decomposition and copper (I) passivation in the presence of a bigger surface area. Oxidative roasting at 750 °C converted pyrite–pyrrhotite to hematite without liberating additional gold, indicating limited benefit from thermal treatment. POX was conducted at 190 °C and 10 bar O2 dissolved 33% of the solids and yielded only 26% of gold in a thiosulfate leaching step with 50% of the thiosulfate consumption. In contrast, a two-step oxidative ammoniacal conditioning (0.4 M NH3 + 10 mM Cu2+ for 42 h) followed by thiosulfate leaching boosted gold extraction from 71% to 85% while cutting thiosulfate consumption from 48.4 to 29.0 kg t−1. The results demonstrate that among the pretreatments investigated, oxidative ammoniacal pre-leaching provides the most effective and environmentally benign route to unlock encapsulated gold and enhance reagent efficiency for thiosulfate processing of refractory gold ore. Full article
(This article belongs to the Section Chemical Processes and Systems)
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21 pages, 2068 KB  
Article
Multi-Objective Optimization of Supercritical Water Oxidation for Radioactive Organic Anion Exchange Resin Wastewater Using GPR–NSGA-II
by Yabin Jin, Tiantian Xu, Le Zhang, Qian Zhang, Liang Zhou, Zhe Shen and Zhenjie Wan
Processes 2025, 13(12), 3759; https://doi.org/10.3390/pr13123759 - 21 Nov 2025
Abstract
Radioactive organic anion exchange resins present a significant challenge in nuclear power plant waste disposal due to their volatility, instability, and biotoxicity. Based on experimental degradation data from the supercritical water oxidation (SCWO) of organic anion exchange resin waste liquids from the nuclear [...] Read more.
Radioactive organic anion exchange resins present a significant challenge in nuclear power plant waste disposal due to their volatility, instability, and biotoxicity. Based on experimental degradation data from the supercritical water oxidation (SCWO) of organic anion exchange resin waste liquids from the nuclear industry, this study conducted correlation analysis, cluster analysis, and Sobol sensitivity analysis of key process parameters. The results indicate that temperature is the primary factor influencing chemical oxygen demand (COD) and total nitrogen (TN) removal, while oxidant dosage exhibits a notable synergistic effect on nitrogen transformation. A Gaussian Process Regression–Non-Dominated Sorting Genetic Algorithm II (GPR–NSGA-II) multi-objective optimization model was developed to balance COD/TN removal rate and treatment cost. The optimal operating conditions were identified as a temperature of 472.2 °C, an oxidant stoichiometric ratio (OR) of 136%, an initial COD concentration of 73,124 mg·L−1, and a residence time of 3.8 min. Under these conditions, COD and TN removal efficiencies reached 99.63% and 32.92%, respectively, with a treatment cost of 128.16 USD·t−1. The proposed GPR–NSGA-II optimization strategy provides a methodological foundation for process design and economic assessment of SCWO in treating radioactive organic resin waste liquids and can be extended to other studies involving high-concentration, refractory organic wastewater treatment. Full article
(This article belongs to the Section Environmental and Green Processes)
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43 pages, 23857 KB  
Article
Sensitivity Analysis and Potential Prediction of Heavy Oil Reservoirs Under Different Steam Flooding Methods
by Lu Jia, Guowei Shi, Xing Lu, Xixu Li, Mingju Lan and Junhao Li
Processes 2025, 13(12), 3758; https://doi.org/10.3390/pr13123758 - 21 Nov 2025
Abstract
Heavy oil reservoirs often enter a high-water-cut and low-production stage after multiple cycles of steam stimulation. Converting to steam flooding can enhance recovery, yet the reliable prediction of incremental production potential and optimal design of injection–production parameters remain limited. In this study, a [...] Read more.
Heavy oil reservoirs often enter a high-water-cut and low-production stage after multiple cycles of steam stimulation. Converting to steam flooding can enhance recovery, yet the reliable prediction of incremental production potential and optimal design of injection–production parameters remain limited. In this study, a real heavy oil reservoir block was selected to develop a hybrid modeling framework integrating numerical simulation and machine learning for predicting steam flooding performance. A conceptual model was established on a numerical simulation platform to reproduce the transition from cyclic stimulation to continuous steam flooding, analyzing temperature, oil saturation, and recovery evolution under different geological, operational, and process conditions. Sensitive parameters were identified through single- and multi-factor analyses, and mathematical models for multiple injection–production schemes—continuous, cyclic, and asynchronous—were constructed for optimization. A comprehensive multi-scenario dataset combining simulation and field data was used to train and validate several machine learning models, including artificial neural networks, gradient boosting decision trees, XGBoost, and LightGBM. Among them, the LightGBM model achieved the highest predictive accuracy (R2 = 0.99) and computational efficiency. The proposed framework enables the rapid and reliable prediction of incremental oil potential and provides a robust tool for optimizing steam flooding parameters, offering significant value for field-scale heavy oil development. Full article
(This article belongs to the Topic Exploitation and Underground Storage of Oil and Gas)
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37 pages, 5804 KB  
Review
Layered Double Hydroxide-Based Materials for Wastewater Treatment: Recent Progress in Multifunctional Environmental Applications
by Milica Hadnadjev-Kostic, Tatjana Vulic, Djurdjica Karanovic, Ana Tomic and Dragoljub Cvetkovic
Processes 2025, 13(12), 3757; https://doi.org/10.3390/pr13123757 - 21 Nov 2025
Abstract
Layered double hydroxides (LDHs) have gained increasing attention as versatile materials in environmental remediation, particularly for wastewater treatment. Their unique structural properties, such as tunable metal cation composition, interlayer anion exchange, and structural memory effects, make them suitable materials for a broad range [...] Read more.
Layered double hydroxides (LDHs) have gained increasing attention as versatile materials in environmental remediation, particularly for wastewater treatment. Their unique structural properties, such as tunable metal cation composition, interlayer anion exchange, and structural memory effects, make them suitable materials for a broad range of applications. In addition to these intrinsic properties, thermally treated LDH-derived mixed metal oxides have emerged as a key focus, exhibiting enhanced activity through tailored structural, electronic, and textural properties. This review presents an up-to-date and systematic overview of recent advancements in the design and application of LDH-based materials, with a focus on photocatalytic degradation of organic dyes, adsorption of contaminants, and light-activated antimicrobial activity. The review also explores emerging photocatalytic applications in correlation with surface engineering, heterojunction formation, and thermal activation to enhance the overall efficiency. In addition, the synergy between antimicrobial activity and photocatalysis is discussed in the context of achieving multifunctional microbial control in water treatment. Finally, current challenges and future perspectives are addressed, including recyclability, scale-up potential, and the development of LDH composites as sustainable alternatives to conventional photocatalysts. This review aims to support researchers in advancing LDH-based technologies toward more efficient and versatile environmental remediation solutions. Full article
(This article belongs to the Special Issue Advances in Adsorption of Wastewater Pollutants)
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