Search Results (22)

This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO₂ geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project in the Ordos Basin, eight full-chain carbon capture, utilization, and storage (CCUS) scenarios were analyzed. The results indicate that environmental and cost performance are primarily influenced by technology choices across carbon capture, transport, and storage stages. The scenario employing potassium carbonate-based capture, pipeline transport, and brine reinjection after a reverse osmosis treatment (S5) achieved the most balanced outcome. Breakeven analyses under three carbon price projection models revealed that carbon price trajectories critically affect project viability, with a steadily rising carbon price enabling earlier profitability. By decoupling CCUS from power systems and focusing on unit CO₂ removal, this study provides a transparent and transferable framework to support cross-sectoral deployment. The findings offer valuable insights for policymakers aiming to design effective CCUS support mechanisms under future carbon neutrality targets. Full article

The mechanism of low- to middle-rank coal seam gas accumulation in the Baode block on the eastern edge of the Ordos Basin is well understood. However, exploration efforts in the Shizuishan area on the western edge started later, and the current understanding of enrichment and accumulation rules is unclear. It is important to systematically study enrichment and accumulation, which guide the precise exploration and development of coal seam gas resources in the western wing of the basin. The coal seam collected from the Shizuishan area of Ningxia was taken as the target. Based on drilling, logging, seismic, and CBM (coalbed methane) test data, geological conditions were studied, and factors and reservoir formation modes of CBM enrichment were summarized. The results are as follows. The principal coal-bearing seams in the study area are coal seams No. 2 and No. 3 of the Shanxi Formation and No. 5 and No. 6 of the Taiyuan Formation, with thicknesses exceeding 10 m in the southwest and generally stable thickness across the region, providing favorable conditions for CBM enrichment. Spatial variations in burial depth show stability in the east and south, but notable fluctuations are observed near fault F1 in the west and north. These burial depth patterns are closely linked to coal rank, which increases with depth. Although the southeastern region exhibits a lower coal rank than the northwest, its variation is minimal, reflecting a more uniform thermal evolution. Lithologically, the roof of coal seam No. 6 is mainly composed of dense sandstone in the central and southern areas, indicating a strong sealing capacity conducive to gas preservation. This study employs a system that fuses multi-source geological data for analysis, integrating multi-dimensional data such as drilling, logging, seismic, and CBM testing data. It systematically reveals the gas control mechanism of “tectonic–sedimentary–fluid” trinity coupling in low-gentle slope structural belts, providing a new research paradigm for coalbed methane exploration in complex structural areas. It creatively proposes a three-type CBM accumulation model that includes the following: ① a steep flank tectonic fault escape type (tectonics-dominated); ② an axial tectonic hydrodynamic sealing type (water–tectonics composite); and ③ a gentle flank lithology–hydrodynamic sealing type (lithology–water synergy). This classification system breaks through the traditional binary framework, systematically explaining the spatiotemporal matching relationships of the accumulated elements in different structural positions and establishing quantitative criteria for target area selection. It systematically reveals the key controlling roles of low-gentle slope structural belts and slope belts in coalbed methane enrichment, innovatively proposing a new gentle slope accumulation model defined as “slope control storage, low-structure gas reservoir”. These integrated results highlight the mutual control of structural, thermal, and lithological factors on CBM enrichment and provide critical guidance for future exploration in the Ningxia Autonomous Region. Full article

The effect of the pore–fracture structure on the porosity and permeability affects the production process of tight sandstone gas. In this paper, 12 groups of tight sandstone samples are selected as the object, and the pore–fracture volume of a tight reservoir is quantitatively characterized by a high-pressure mercury injection test. The multifractal and single fractal characteristics of different types of samples are calculated by fractal theory. On this basis, the pore volume variation under stress is discussed through the overlying pressure pore permeability test, and the pore–fracture compressibility is calculated. Finally, the main factors affecting the stress sensitivity of tight sandstone are summarized from the two aspects of the pore structure and mineral composition. The results are as follows. (1) The samples could be divided into types A and B by using the mercury-in and mercury-out curves. There is a significant hysteresis loop in the mercury inlet and outlet curves of type A, and the efficiency of the mercury inlet and outlet in the pores is relatively higher. The mercury removal curve of type B is almost parallel, and its mercury removal efficiency is relatively lower. (2) The applicability of singlet fractals in characterizing the heterogeneity of micropores is higher than that of multifractals. This is because the single fractal characteristics of the two types of samples have significant differences, while the differences in the multifractals are relatively weak. (3) A pore diameter of 100–1000 nm provides the main compression space for the type A samples. A pore distribution heterogeneity of 100–1000 nm affects the compression effect and stress sensitivity of this type B sample. Full article

Pisco is an emblematic spirit in Peru and Chile, made from fermented grapes, gaining growing scientific interest over the last two decades. This study aimed to map 20 years of research on Pisco through a systematic bibliometric review. A search was conducted in the Scopus database covering the period from 2004 to 2024, applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology for the transparent selection of scientific articles. The search strategy considered titles, abstracts, and keywords, using the terms “Pisco” and “schnapps”, excluding unrelated fields such as geology (basin, seismic, fossil). The initial search yielded 360 records. After removing non-original articles (books, book chapters, conference papers, and reviews), 101 articles remained. A further screening excluded irrelevant studies (e.g., those referring to the city of Pisco rather than the beverage), resulting in 78 articles included for final analysis. It was observed that 19% of the studies focus on the history, culture, and appellation of origin; 14% on environmental sustainability; 10% on innovation and quality; and 9% on the bioactive properties of by-products. Other areas include extraction technologies (9%), distillation process modeling (8%), and marketing and economics (8%), among others. Recent trends are related to clean production practices. Thus, Pisco by-products and their components can be exploited by applying technologies such as supercritical fluids, drying, and biofilms, while, for waste management, the processes of composting, solar photo-Fenton, and ozonation can be applied. Moreover, it is important to highlight that the valorization of Pisco by-products opens opportunities for translation into the market, particularly in developing cosmetics, nutritional supplements, and bio-packaging materials, contributing to sustainability and innovation in new industries. However, a more holistic view is still needed in Pisco research. These findings suggest that future research should prioritize the integration of consumer-based sensory evaluations and sustainable production innovations to optimize Pisco’s quality, enhance market acceptance, and promote environmentally responsible industry practices. Full article

As a rare metal, lithium plays a pivotal role in strategic critical metal mineral resources and is one of the critical metals for developing the contemporary social economy. The Li-rich layers in the Xian’an coalfield in Guangxi Province were taken as a typical study area in this research, the material sources of Li-rich strata were discussed, and the enrichment process of Li-rich layers was revealed through geochemical research methods. The coal seams in this area have abnormal enrichment points with high lithium content, but there is a certain inhomogeneity in the plane and longitudinal distribution. This research studies the causes and material sources around the multi-layer lithium-extruded layers in the longitudinal distribution of coal-based strata. Through mineralogy and geochemical research methods, this research shows that Li-rich mineralization results from the combined action of terrigenous material and volcaniclastic source inputs, water–rock processes, and fluid inputs. The Li-bearing rocks formed over three periods, which are the weathering, sedimentation, and diagenesis stages. Based on factors such as provenance and geological processes, this study analyzes the genesis of Li-rich layers and provides a theoretical basis for the future prospecting of lithium ore deposits. Full article

Coal mine safety is vital not only for maintaining production operations but also for ensuring the industry’s sustainable development. The threat posed by mine water hazards is especially severe, growing more critical as mining activities become more intense and reach greater depths. Currently, common methods for identifying water sources mainly depend on hydrochemical data, supplemented by analyses of water level and temperature changes. However, due to constraints in cost, time, and the complexity of mining conditions, there is still significant potential for enhancing water source identification techniques. To advance water source identification, this study introduces a novel approach that uses a spectrophotometer to gather spectral data from water sources. These data are then integrated with a bat algorithm (BA)-optimized radial basis function (RBF) neural network to develop a model for identifying water inrush sources. At Baode Coal Mine in China, 105 water samples from four different sources were collected and analyzed using spectral data. The baseline was corrected using the second derivative technique to ensure the data’s integrity. Additionally, 54 sets of historical hydrochemical data were collected for comparison with the spectral data-based model. Theoretical analysis and experimental results show that both hydrochemical and spectral data are effective for identifying water inrush sources. The hydrochemical data model achieved an accuracy of about 90%, whereas the model based on spectral data reached an average accuracy of 95%. Among the tested models: RBF, GA-RBF, PSO-RBF, BA-RBF, and the BA-RBF model demonstrated superior performance, providing the most rapid and accurate identification of water inrush. Full article

This study analyzes collapse hazards for complex interactions between geology, meteorology, and human activities in the Changbai Mountain region, focusing on how to cope with these features through machine learning. Using a dataset of 651 collapse events, this study evaluates four machine learning methods, Support Vector Machine (SVM), Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM), to deal with complex nonlinear data structures. To overcome the limitations of a single-feature selection method, a variance inflation factor is introduced to optimize the selection of collapse risk factors. The transparency and interpretability of the modeling results are enhanced by combining the Shapley Additive Explanations (SHAP) with interpretable artificial intelligence. Model performance is evaluated on a test set by several statistical metrics, which shows that the optimized random forest model performs best and outperforms SVM, XGBoost, and LightGBM. The SHAP analysis results indicate that distance from the road is a key factor for collapse hazard. This study emphasizes the need for collapse management strategies that provide interpretable solutions for collapse hazard assessment. Full article

The degradation of groundwater quality due to mining activities is a major public concern globally. This study employed a combination of methods (multivariate statistics, Self-organizing mapping, and PHREEQC hydrogeochemical simulation) to uncover the hydrochemical characteristics and processes of mine water in the Kailuan mining area. Self-organizing mapping (SOM) clustering divided the mine water into three groups, TDS values gradually increased from the first to the third group, and the hydrogeochemical type of mine water gradually changed from Na-HCO₃ and CaMg-HCO₃ to CaMg-SO₄, Na-Cl, and mixed types. Principal component analysis (PCA) revealed that water–rock action and evaporation concentration were major ion concentration factors. According to the molar ion concentration ratio method, the main ions in mine water in Kailuan mining area originate from silicate and sulfate, and a small amount from carbonate rock weathering, and they are influenced by cation exchange. As a result of the PHReactor EQuilibrium Code (PHREEQC) simulation results, it can be concluded that better hydrodynamic conditions in mines are primarily controlled by carbonate dissolution. Mine water with poorer hydrodynamic conditions is mainly controlled by sulfate and carbonate dissolution, with sulfate dissolution having a greater effect. The results of this study provide an important scientific basis for the safe mining of mines and the protection of groundwater resources. Full article

Deep well injection and storage is an emerging technology for realizing the low-cost treatment of extremely large quantities of three types of waste in coal mines in China, while simultaneously supporting coordinated development that considers its impact on the ecological environment. There has been significant progress in research on the geological storage of carbon dioxide in China. However, the geological storage of fluids such as mine water and high-salinity water needs to be studied further. Based on a comprehensive analysis of the lithology, mineral composition, physical and mechanical characteristics, and spatial structure of the Liujiagou and Shiqianfeng formations in a mining area in the Ordos Basin, we determined the geological storage space for fluids, predicted the storage potential, and evaluated the feasibility of deep geological storage of high-salinity water in coal mines. In the study area, the Liujiagou Formation is dominated by fine sandstone and siltstone, while the Shiqianfeng Formation is dominated by medium sandstone and conglomerate. The main storage space comprises micro-cracks, as well as intergranular, dissolution, and intergranular pores. Among these, the intergranular pores are the most conducive to reservoir development. The burial depth intervals of 1820–1835 m, 1905–1920 m, and 2082–2098 m are favorable for storage and are characterized by high porosities, permeabilities, and storage capacities. The effective storage capacity within a 100 m radius of the storage well was estimated to be 33.15 × 10⁴ m³. The effective storage capacity in the favorable area is 27.69 × 10⁴ m³, accounting for 83.50% of the total storage capacity. The Liujiagou and Shiqianfeng formations thus can serve as favorable reservoirs for deep well injection and storage of high-salinity water in the Ordos Basin. This research provides new ideas for the treatment of high-salinity water in coal mines in the Ordos Basin and technical support for deep well injection and the storage of high-salinity water. Full article

Deep well injection and storage (DWIS) has recently been proposed and implemented to achieve zero mine water emissions. In 2023, DWIS for highly saline mine water was successfully applied to a local mine in the Ordos Basin for the first time with excellent performance. However, the storage characteristics of highly saline mine water in the storage layer during DWIS remain unclear. This study was conducted in situ with real-time, online monitoring of instantaneous flow and injection pressure, along with synchronous micro-seismic monitoring during the early stages of DWIS, based on the geological conditions and spatial structure of the storage layer. The results indicated that the early seepage characteristics of the fluid geological storage did not conform to Darcy’s law. Within a certain pressure range, as the water pressure increased, the flow also increased. However, beyond this range, further increases in pressure caused a gradual decline in the flow. During the initial phase of storage, the migration of high-salinity mine water within the storage layer occurred in two stages: breakthrough and stabilization. During the breakthrough stage, the water injection pressure propagated to the flooding front, overcoming the formation stress and expanding the storage space. At this stage, mine water primarily filled the pore microcracks within the flooding front. In the initial 10 days of storage, high-salinity mine water in the study area affected approximately 42,104 m² of the storage layer plane. The injection well affected an area nearly 200 m in depth, extending approximately 190 m northward and approximately 40 m upward. The predominant diffusion directions were northeast and east–southeast from the injection well. These findings could provide valuable insights into the treatment of highly saline mine water in the Ordos Basin, demonstrate the feasibility and safety of DWIS, and offer significant scientific contributions to the prevention and control of mine water pollution. Full article

Coal pillars are loaded and unloaded repeatedly when mining, which lead to fractures in the coal close, open, generate and expand. As a result, the permeability of coal is changed. The high permeability fractures in coal and rock between the upper gobs and the lower working faces are the main channels for fresh air entering the upper gob, which could induce spontaneous combustion of coal in gob. To identifying the air leakage channels, multiple mining of closely coal seams was numerically conducted with three working face layouts. The failure and permeability characteristic of coal pillar in closely coal seams gob under multiple mining were obtained and analyzed. When the working faces are mined, the vertical stress and horizontal stress of the upper coal pillar in gob load and unload synchronously in all three working face layouts. The laterally directed horizontal stress could unload to zero due to no confine on the lateral side of coal pillar. The stress in the middle of upper coal pillar loads continuously until the lower working face is mined. When the lower coal seam working face is mined, the coal and rock between the upper and lower coal seams damage in shear and tension. When the lower coal seam working face is staggered from the upper coal seam working face, the permeability of the coal and rock pillar increases more than 22000 times due to tension damage of the coal and rock pillar. As a result, the coal and rock pillar is the main channel for fresh air flowing into the upper gob. The high permeability coal pillar provides favorable conditions for spontaneous combustion of coal in gob. Full article

In geology and mineralogy, optical microscopic images have become a primary research focus for intelligent mineral recognition due to their low equipment cost, ease of use, and distinct mineral characteristics in imaging. However, due to their close reflectivity or transparency, some minerals are not easily distinguished from other minerals or background. Secondly, the number of background pixels often vastly exceeds the number of pixels for individual mineral particles, and the number of pixels of different mineral particles in the image also varies significantly. These have led to the issue of data imbalance. This imbalance results in lower recognition accuracy for categories with fewer samples. To address these issues, a flexible ensemble learning for semantic segmentation based on multiple optimized Res-UNet models is proposed, introducing dice loss and focal loss functions and incorporating a pre-positioned spatial transformer networks block. Twelve optimized Res-UNet models were used to construct multiple Res-UNet ensemble learnings using heterogeneous ensemble strategies. The results demonstrate that the system integrated with five learners using the weighted voting fusion method (RUEL-5-WV) achieved the best performance with a mean Intersection over Union (mIOU) of 91.65 across all nine categories and an IOU of 84.33 for the transparent mineral (gangue). The results indicate that this ensemble learning scheme outperforms individual optimized Res-UNet models. Compared to the classical Deeplabv3 and PSPNet, this scheme also exhibits significant advantages. Full article

The processes of coal mining and washing generate a substantial amount of coal gangue. During prolonged outdoor storage, this waste can lead to both direct and indirect environmental pollution, as well as geological hazards. Recent research has indicated that the redox processes of coal gangue are regulated by microorganisms. Techniques such as the application of biocides and the facilitation of microbial interactions have proven effective in controlling the acidic pollution of coal gangue in the short term. However, conventional doping methods that couple sulfate-reducing bacteria with biocides face challenges, including a short effective duration and poor stability. To address these issues, this study utilized corn straw biochar as a microbial attachment material and incorporated water-retaining agents as slow-release biocide carriers, resulting in the development of an environmentally friendly microbial remediation material. This study selected 0.6 g of biochar produced from the pyrolysis of corn straw at 700 °C to immobilize sulfate-reducing bacteria. Additionally, 0.6 g of polyacrylamide was used to prepare a slow-release bactericide with 100 mL of a sodium dodecyl sulfate solution at a concentration of 50 mg·L⁻¹. The composite remediation material successfully raises the pH of weathered coal gangue leachate from 4.32 to 6.88. Its addition notably reduces the sulfate ion concentration in the weathered coal gangue, with sulfate content decreasing by 86.45%. Additionally, the composite material effectively lowers the salinity of the weathered coal gangue. The composite immobilizes heavy metal ions within the weathered coal gangue, achieving an approximate removal rate of 80% over 30 days. Following the introduction of the composite material, significant changes were observed in the dominant microbial communities and population abundances on the surface of the coal gangue. The composite demonstrated the ability to rapidly, sustainably, and effectively remediate the acidification pollution associated with coal gangue. Full article

The study of lithium (Li), gallium (Ga), and rare earth elements (REY) within coal-bearing strata represents a cutting-edge concern in coal geology, ore deposit studies, and metallurgy research. With the rapid advancement of technology and emerging industries, the global demand for Li-Ga-REY has significantly escalated. Several countries worldwide are facing immense pressure due to shortages in Li-Ga-REY resources. Coal-associated Li-Ga-REY depositions have emerged as a pivotal direction for augmenting Li-Ga-REY reserves. To ascertain the enrichment distribution patterns and genetic mechanisms of Li-Ga-REY within the coal-bearing strata of the late Permian Heshan Formation in Wanfu mine, Xian’an Coalfield, Guangxi Province, this study carried out comprehensive testing and analysis on Li-Ga-REY enriched in the mineralized layers within the strata. The Heshan Formation in Wanfu mine presents four layers of Li-Ga-REY-enriched mineralization, labeled from bottom to top as mineralized layers I, II, III, and IV, corresponding to coal seams K5, K4, K3, and K2. These critical metals are predominantly hosted within clay minerals (kaolinite, illite/smectite, and chlorite). The enrichment of critical metals within the Heshan Formation is closely related to terrigenous detrital materials from the Daxin paleocontinent, volcanic detrital materials induced by the Emeishan mantle plume and the Yuenan magmatic arc. The accumulation of Li-Ga-REY and other critical elements within the mineralized layers is the result of inputs from terrestrial and volcanic detrital sources, interactions between peatification and diagenesis stages, and occasionally the input of metal-enriched fluids. In the mineralized layers I, II, and III, the content of lithium oxide (Li₂O) surpasses the boundary grade, and the levels of REY, Ga, and (Nb,Ta)₂O₅ are close to boundary grades, indicating promising exploration prospects. The Wanfu mine in the Xian’an Coalfield can be considered a primary target zone for the exploration and development of coal-associated critical metal resources in Guangxi. Full article

Pore structure heterogeneity of coal reservoirs restricts the diffusion-seepage process of coalbed methane, thereby restricting the production capacity of coalbed methane. Therefore, 10 coal samples from the Linxing area are taken as an objective, and high-pressure mercury intrusion testing was used to describe the pore structure distribution of all the coal samples. On this basis, four single and multifractal models were used to perform fractal calculations, and correlation analysis was conducted on the mercury advance and retreat fractal dimension values to clarify the physical significance of mercury removal fractal dimension values. Finally, the relationship between fractal dimension values of mercury curves and pore structure parameters was clarified, and the applicability of various fractal models in characterizing pore structure heterogeneity was explored. All the samples can be divided into type A and B by using pore volume percentage greater than 1000 nm and the mercury removal efficiency. The T model has universality and the strongest correlation in characterizing the heterogeneity of pore volume distribution in samples. A fractal parameter based on high-pressure mercury injection curve was obtained, and was then used to quantitatively characterize the pore and fracture structure of coal reservoirs. This parameter is used to characterize the complexity of gas and water transport during coalbed methane production, further elucidating the coalbed methane production process under the constraint of pore and fracture structure in coal reservoirs. Full article