The rock mass failure induced by deep mining exhibits pronounced spatial heterogeneity and diverse mechanisms,with its microseismic responses serving as effective indicators of regional failure evolution and instabili...The rock mass failure induced by deep mining exhibits pronounced spatial heterogeneity and diverse mechanisms,with its microseismic responses serving as effective indicators of regional failure evolution and instability mechanisms.Focusing on the Level VI stope sublayers in the Jinchuan#2 mining area,this study constructs a 24-parameter index system encompassing time-domain features,frequency-domain features,and multifractal characteristics.Through manifold learning,clustering analysis,and hybrid feature selection,15 key indicators were extracted to construct a classification framework for failure responses.Integrated with focal mechanism inversion and numerical simulation,the failure patterns and corresponding instability mechanisms across different structural zones were further identified.The results reveal that multiscale microseismic characteristics exhibit clear regional similarities.Based on the morphological features of radar plots derived from the 15 indicators,acoustic responses were classified into four typical types,each reflecting distinct local failure mechanisms,stress conditions,and plastic zone evolution.Moreover,considering dominant instability factors and rupture modes,four representative rock mass instability models were proposed for typical failure zones within the stope.These findings provide theoretical guidance and methodological support for hazard prediction,structural optimization,and disturbance control in deep metal mining areas.展开更多
Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.I...Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.In this study,a ferric sulfate bio acid(BA)with an acidity of~0.2 mol/L H^(+),generated through regulated pyrite bio-oxidation,was used to leach REEs and critical metals(CMs)from coal refuse(ground to<1 mm)after 20-min roasting at 600℃.The influences of solid/liquid(S/L)ratio(100-300 g/L)and leaching temperature(25-95℃)on the leaching performance were examined.The leaching mechanisms were investigated by conducting stepwise precipitation tests and spectroscopic characterization.Results show that raising the leaching temperature to≥65℃accelerated the REE leaching kinetics but causes the loss of light REEs(LREEs)after reaching peak values at 30-60 min.Stage precipitation tests reveal that the loss is due to the incorporation of REEs,especially for LREEs,by gypsum and schwertmannite.The peak total REE(TREE)recovery of the BA leaching reaches 24.9%after 30 min of leaching at75℃with a S/L ratio of 200 g/L.Implementing the three-stage counter-current leaching increases the overall TREE recovery to 31.8%by recovering the REEs incorporated in the Fe and Ca precipitates.Meanwhile,promising recovery values of Li(55.5%),Mn(74.6%),Ni(41.6%),and Co(35.3%)are also achieved.This method provides a sustainable approach to extract REEs and critical metals from coal waste materials with a high treatment capacity.展开更多
Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have di...Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.展开更多
This study addresses the challenge of predicting zinc(Zn)recovery from carbonate ores via sodium hydroxide(NaOH)leaching.This complex process influenced by variable ore composition,surface passivation effects,and nonl...This study addresses the challenge of predicting zinc(Zn)recovery from carbonate ores via sodium hydroxide(NaOH)leaching.This complex process influenced by variable ore composition,surface passivation effects,and nonlinear reaction dynamics,which complicate reagent optimization and process control in hydrometallurgical operations.To tackle this,a dataset containing 422 experimental observations was compiled from previous studies,incorporating ore composition and process parameters,such as NaOH concentration,leaching time,temperature,and solid-to-liquid ratio.Four regression models(decision tree,neural network,generalized additive model,and random forest)were trained and evaluated using performance metrics,such as coefficient of determination(R^(2)),root mean squared error(RMSE),mean absolute error(MAE),mean absolute percentage error(MAPE),and symmetrical mean absolute percentage error(SMAPE).Among these,the random forest model achieved the best predictive accuracy,with R^(2)value of 0.8541 on the test set and the lowest error rates,demonstrating its effectiveness in capturing the complex relationships between input variables and Zn recovery.Explainable artificial intelligence,particularly SHapley additive exPlanations(SHAP)analysis,revealed that NaOH concentration,leaching time,and solid-to-liquid ratio had the most positive influence on Zn recovery,whereas elements such as Ca,Fe,and Pb had inhibitory effects.These findings align with known geochemical behavior and provide valuable insights for reagent optimization and process effi-ciency in leaching processes.This study demonstrates the practical potential of machine learning in mineral processing,offering a scalable framework for optimizing Zn recovery from non-sulfide ores and a data-driven approach to enhance decision-making in hydrometallurgical applications.展开更多
Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations...Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations to investigate mechanical behavior,fracture development,and energy evolution of CRF containing 54%aggregate content with three grain-size distributions(5-10,10-20,and 20-30 mm).Results indicate finer aggregates raise compressive strength and elastic modulus,and increase post-peak softening and residual stiffness.Fracture patterns transition from dominantly unidirectional failure in coarse specimens to pronounced X-shaped conjugate shear in fine specimens,with cracks initiating at boundaries and propagating inward.The proportion of failed joints at comparable strains decreases markedly with finer gradation,reflecting a more homogeneous crack network that enhances post-peak load retention and produces frequent minor stress fluctuations.Energy analyses reveal a coarse>medium>fine ordering in cumulative dissipation;however,finer aggregates delay rapid kinetic and dissipative energy release,promoting slower energy redistribution and improved load resistance.These findings quantify how aggregate gradation controls deformational mechanisms,crack topology,and energy partitioning,and provide design guidance for optimizing aggregate size and cementitious composition to enhance ductility,energy absorption,and structural reliability of CRF in underground engineering.展开更多
Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM)....Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.展开更多
Mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion ...Mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion is used to deduce the stress redistribution around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method （BEM） was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the longwall panel. In velocity tomograms, the main zones of the stress redistribution arotmd the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the longwall mining panel continuously and subsequently to improve safety of mining operations.展开更多
Prediction of surface subsidence caused by longwall mining operation in inclined coal seams is often very challenging. The existing empirical prediction methods are inflexible for varying geological and mining conditi...Prediction of surface subsidence caused by longwall mining operation in inclined coal seams is often very challenging. The existing empirical prediction methods are inflexible for varying geological and mining conditions. An improved influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, the original Knothe function has been transformed to produce a continuous and asymmetrical subsidence influence function. The empirical equations for final subsidence parameters derived from col- lected longwall subsidence data have been incorporated into the mathematical models to improve the prediction accuracy. A number of demonstration cases for longwall mining operations in coal seams with varying inclination angles, depths and panel widths have been used to verify the applicability of the new subsidence prediction model.展开更多
In the Kaiping Coal field,mining of five coal seams,located within 80 m in the Kailuan Group,#5,#7,#8,#9 and#12 coal seam,is difficult due to small interburden thickness,concentrated stress distributions,high coal sea...In the Kaiping Coal field,mining of five coal seams,located within 80 m in the Kailuan Group,#5,#7,#8,#9 and#12 coal seam,is difficult due to small interburden thickness,concentrated stress distributions,high coal seam metamorphism,and complex geological conditions.By using the ZTR12 geological penetration radar(GPR)survey combined with borehole observations,the overburden caving due to mining of the five coals seams was measured.The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan,which provides a measurement basis for the control of rock strata in close multiple coal seam mining.For the first time,it was found that the overburden caving pattern shows a periodic triangular caved characteristic.Furthermore,it is proposed that an upright triangular collapsed pile masonry and an inverted triangular with larger fragments piled up alternately appear in the lower gob.The research results show that the roof structure formed in the gob area can support the key overlying strata,which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close coal seams.展开更多
Ground movements due to longwall mining operations have the potential to damage the hydrological balance within as well as outside the mine permit area in the form of increased surface ponding and changes to hydrogeol...Ground movements due to longwall mining operations have the potential to damage the hydrological balance within as well as outside the mine permit area in the form of increased surface ponding and changes to hydrogeological properties. Recently, the Office of Surface Mining, Reclamation and Enforcement(OSMRE) in the USA, has completed a public comment period on a newly proposed rule for the protection of streams and groundwater from adverse impacts of surface and underground mining operations(80 FR 44435). With increased community and regulatory focus on mining operations and their potential to adversely affect streams and groundwater, now there is a greater need for better prediction of the possible effects mining has on both surface and subsurface bodies of water. With mining induced stress and strain within the overburden correlated to changes in the hydrogeological properties of rock and soil, this paper investigates the evaluation of the hydrogeological system within the vicinity of an underground mining operation based on strain values calculated through a surface deformation prediction model. Through accurate modeling of the pre- and post-mining hydrogeological system, industry personnel can better depict mining induced effects on surface and subsurface bodies of water aiding in the optimization of underground extraction sequences while maintaining the integrity of water resources.展开更多
The distribution of the final surface subsidence basin induced by longwall operations in inclined coal seam could be significantly different from that in flat coal seam and demands special prediction methods. Though m...The distribution of the final surface subsidence basin induced by longwall operations in inclined coal seam could be significantly different from that in flat coal seam and demands special prediction methods. Though many empirical prediction methods have been developed, these methods are inflexible for varying geological and mining conditions. An influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, significant modifications have been made to the original Knothe function to produce an asymmetrical influence function. The empirical equations for final subsidence parameters derived from US subsidence data and Chinese empirical values have been incorpo- rated into the mathematical models to improve the prediction accuracy. A corresponding computer program is developed. A number of subsidence cases for longwall mining operations in coal seams with varying inclination angles have been used to demonstrate the applicability of the developed subsidence prediction model.展开更多
The broad objective of this research was to improve current surface mining practices and reduce negative environmental impact of overburden removal in West Virginia(WV).The specific objectives were to(i)compare conven...The broad objective of this research was to improve current surface mining practices and reduce negative environmental impact of overburden removal in West Virginia(WV).The specific objectives were to(i)compare conventional surface mining method(drilling,blasting,digging,and loading)to a surface miner(SM)method,and(ii)apply the analytical hierarchy process(AHP)to help select the optimal mining method based on production,cost and environmental criteria.The design and the procedures used in this research involve five interrelated modules:(i)rock properties of overburden in WV,(ii)drilling and blasting,(iii)digging and loading,(iv)SM method,and(v)comparative analysis and selection of the optimal mining method by AHP.Results of this research indicate that application of SM method would yield higher cost of overburden removal than conventional mining methods in rocks with a high unconfined compressive strength and abrasivity.A significant advantage of SM method,where applicable,is the elimination of the negative environmental impacts associated with blasting.展开更多
Equipment plays an important role in open pit mining industry and its cost competence at efficient operation and maintenance techniques centered on reliability can lead to significant cost reduction.The application of...Equipment plays an important role in open pit mining industry and its cost competence at efficient operation and maintenance techniques centered on reliability can lead to significant cost reduction.The application of optimal maintenance process was investigated for minimizing the equipment breakdowns and downtimes in Sungun Copper Mine.It results in the improved efficiency and productivity of the equipment and lowered expenses as well as the increased profit margin.The field operating data of 10 trucks are used to estimate the failure and maintenance profile for each component,and modeling and simulation are accomplished by using reliability block diagram method.Trend analysis was then conducted to select proper probabilistic model for maintenance profile.Then reliability of the system was evaluated and importance of each component was computed by weighted importance measure method.This analysis led to identify the items with critical impact on availability of overall equipment in order to prioritize improvement decisions.Later,the availability of trucks was evaluated using Monte Carlo simulation and it is revealed that the uptime of the trucks is around 11000 h at 12000 operation hours.Finally,uncertainty analysis was performed to account for the uncertainty sources in data and models.展开更多
Differential Interferometric Synthetic Aperture Radar(DInSAR),a satellite-based remote sensing technique,has application for monitoring subsidence with high resolution over short periods.DInSAR uses radar images to me...Differential Interferometric Synthetic Aperture Radar(DInSAR),a satellite-based remote sensing technique,has application for monitoring subsidence with high resolution over short periods.DInSAR uses radar images to measure centimeter-level surface displacements.In the images,ground resolution can be relatively high,with each data point(pixel)representing the average displacement over an area of several square meters.The image data are acquired regularly which allows subsidence to be monitored sequentially over short periods;imaging periods typically range from weeks to months.Monitoring subsidence over short periods with high spatial resolution has potential to provide insight into the dynamics of subsidence and into relationships between mine advance and subsidence.In this study,for three longwall mines in the western United States,initial subsidence occurring at the start of longwall advance is quantified over short periods(12–72 days).C-band interferometric wide swath Synthetic Aperture Radar(SAR)images from the Sentinel satellites are used to quantify the subsidence.Overall,the data show initial development of subsidence,expansion of the subsidence trough,and the advance of subsidence in the direction of mining.展开更多
Most, if not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated from explosive gas zones(EGZs) in the longwall gob. Since 201...Most, if not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated from explosive gas zones(EGZs) in the longwall gob. Since 2010, researchers at the Colorado School of Mines(CSM) have studied EGZ formation in longwall gobs under two long-term research projects funded by the National Institute for Occupational Safety and Health. Researchers used computational fluid dynamics along with in-mine measurements. For the first time, they demonstrated that EGZs form along the fringe areas between the methane-rich atmospheres and the fresh air ventilated areas along the working face and present an explosion and fire hazard to mine workers. In this study, researchers found that, for progressively sealed gobs, a targeted injection of nitrogen from the headgate and tailgate, along with a back return ventilation arrangement, will create a dynamic seal of nitrogen that effectively separates the methane zone from the face air and eliminates the EGZs to prevent explosions. Using this form of nitrogen injection to create dynamic seals should be a consideration for all longwall operators.展开更多
Longwall mining has a significant influence on gas wells located within longwall chain pillars.Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in ga...Longwall mining has a significant influence on gas wells located within longwall chain pillars.Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings.If the gas well casings are compromised or ruptured,natural gas could migrate into the mine workings,potentially causing a fire or explosion.By the current safety regulations,the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars.The current regulations for gas well pillar design are based on the 1957 Pennsylvania gas well pillar study.The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars.As the guidelines were developed for room-andpillar mining under shallow cover,they are no longer applicable to modern longwall coal mining,particularly,under deep cover.Gas well casing of failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study,conducted by the National Institute for Occupational Safety and Health(NIOSH),presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh Coal Seam.The study results indicate that overburden depth and pillar size are not the only determining factors for gas well stability.The other important factors include subsurface ground movement,overburden geology,weak floor,as well as the type of the construction of gas wells.Numerical modeling was used to model abutment pressure,subsurface deformations,and the response of gas well casings.The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above,within,and below the chain pillars,and the potential location and modes of gas well failures,thereby providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.展开更多
Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs ...Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs is proper machine inspection.Traditional miner safety training includes the use of hardcopy documents and video instructions.However,modern mobile and computer technology offers tremendous potential to improve the training process.In this study,we apply a 360-degree camera,opensource platform WordPress^(TM),and the software Unity3D in order to create materials and tools for the HEOs safety training to help trainees better understand the pre-shift safety machine inspection.The computer-based safety task training developed in this research is tested and implemented at a surface mine in the southern United States.展开更多
Coal seams in Tashan Mine of Datong Coal Group in China average 15 m thick and have been mined by the top coal caving longwall mining method of large mining height. Mining height was 3.8 m and the top coal caving heig...Coal seams in Tashan Mine of Datong Coal Group in China average 15 m thick and have been mined by the top coal caving longwall mining method of large mining height. Mining height was 3.8 m and the top coal caving height was 11.2 m. The gateroad pillar between panels was 38 m. During retreat mining,serious bumps occurred in the gateroads on both sides of the pillar affecting safety production. Therefore,pillarless mining was experimented. Using numerical modeling and comparative study of cases of similar mining condition,it was decided to employ a 6 m wide pillar,rather than the previous 38 m wide pillar.Support system for the gateroads was designed and implemented. During gateroad development,pillar failure conditions and entry deformation were monitored. Hydraulic fracturing method was employed to cut off the K3 sandstone along the entry rib so as to reduce the abutment pressure induced during retreat mining. Support reinforcement method combining grouting and advanced reinforcement methods was proposed to insure stable gateroad ahead of mining. Methane drainage and nitrogen injection were implemented to eliminate hazards associated with mine fire and spontaneous combustion. Since the development of gateroad has just completed,and retreat mining has not begun,the effectiveness of the proposed methods is unknown at this point. However,monitoring will continue until after mining.The results will be published in a separate paper.展开更多
Mining method selection is the first and the most critical problem in mine design and depends on some parameters such as geotechnical and geological features and economic and geographic factors. In this paper, the fac...Mining method selection is the first and the most critical problem in mine design and depends on some parameters such as geotechnical and geological features and economic and geographic factors. In this paper, the factors affecting mining method selection are determined. These factors include shape, thick- ness, depth, slope, RMR and RSS of the orebody, RMR and RSS of the hanging wall and footwall. Then, the priorities of these factors are calculated. In order to calculate the priorities of factors and select the best mining method for Qapiliq salt mine, Iran, based on these priorities, fuzzy analytical hierarchy process （AHP） technique is used. For this purpose, a questionnaire was prepared and was given to the associated experts. Finally, after a comparison carried out based on the effective factors, between the four mining methods including area mining, room and pillar, cut and fill and stope and pillar methods, the stope and nillar mining method was selected as the most suitable method to this mine.展开更多
‘‘Web ground control"(web GC) provides users with instantaneous access to mine design applications anywhere, at any time, through a web browser.Utilizing a web-based multiple-tier architecture, users are able t...‘‘Web ground control"(web GC) provides users with instantaneous access to mine design applications anywhere, at any time, through a web browser.Utilizing a web-based multiple-tier architecture, users are able to easily access ground control designs, perform on-demand calculations in the field, as well as facilitate project collaborations across multiple users, devices, and operating systems.Currently, the web GC platform contains five ground control related design applications previously developed and distributed by the US National Institute of Occupational Safety and Health(NIOSH), that is, analysis of roof bolt stability(ARBS), analysis of longwall pillar stability(ALPS), analysis of retreat mining stability(ARMPS), analysis of retreat mining stability–highwall mining(ARMPS-HWM), and analysis of horizontal stress in mining(AHSM).With respect to design decisions made by the web GC development team, the web GC platform will be able to further integrate future mine design applications providing the mining industry with one of a kind umbrella suite of ground control related software available at ones fingertips.The following paper provides a detailed overview on the current state of the web GC platform with discussions ranging from back-end database development and design to the front-end user-platform interface.Based on current progress in platform development as well as beta testing results, the web GC platform is scheduled for release in the fall of 2018.展开更多
基金financial support from the Distinguished Youth Funds of the National Natural Science Foundation of China(No.52425403)the Hunan Province Graduate Research Innovation Project of China(No.CX20230168)。
文摘The rock mass failure induced by deep mining exhibits pronounced spatial heterogeneity and diverse mechanisms,with its microseismic responses serving as effective indicators of regional failure evolution and instability mechanisms.Focusing on the Level VI stope sublayers in the Jinchuan#2 mining area,this study constructs a 24-parameter index system encompassing time-domain features,frequency-domain features,and multifractal characteristics.Through manifold learning,clustering analysis,and hybrid feature selection,15 key indicators were extracted to construct a classification framework for failure responses.Integrated with focal mechanism inversion and numerical simulation,the failure patterns and corresponding instability mechanisms across different structural zones were further identified.The results reveal that multiscale microseismic characteristics exhibit clear regional similarities.Based on the morphological features of radar plots derived from the 15 indicators,acoustic responses were classified into four typical types,each reflecting distinct local failure mechanisms,stress conditions,and plastic zone evolution.Moreover,considering dominant instability factors and rupture modes,four representative rock mass instability models were proposed for typical failure zones within the stope.These findings provide theoretical guidance and methodological support for hazard prediction,structural optimization,and disturbance control in deep metal mining areas.
文摘Extracting rare earth elements(REEs)from coal refuse is challenging due to their low co ncentrations and poor leachability.Bioleaching has emerged as a sustainable technology to recover REEs from low-grade materials.In this study,a ferric sulfate bio acid(BA)with an acidity of~0.2 mol/L H^(+),generated through regulated pyrite bio-oxidation,was used to leach REEs and critical metals(CMs)from coal refuse(ground to<1 mm)after 20-min roasting at 600℃.The influences of solid/liquid(S/L)ratio(100-300 g/L)and leaching temperature(25-95℃)on the leaching performance were examined.The leaching mechanisms were investigated by conducting stepwise precipitation tests and spectroscopic characterization.Results show that raising the leaching temperature to≥65℃accelerated the REE leaching kinetics but causes the loss of light REEs(LREEs)after reaching peak values at 30-60 min.Stage precipitation tests reveal that the loss is due to the incorporation of REEs,especially for LREEs,by gypsum and schwertmannite.The peak total REE(TREE)recovery of the BA leaching reaches 24.9%after 30 min of leaching at75℃with a S/L ratio of 200 g/L.Implementing the three-stage counter-current leaching increases the overall TREE recovery to 31.8%by recovering the REEs incorporated in the Fe and Ca precipitates.Meanwhile,promising recovery values of Li(55.5%),Mn(74.6%),Ni(41.6%),and Co(35.3%)are also achieved.This method provides a sustainable approach to extract REEs and critical metals from coal waste materials with a high treatment capacity.
基金financially supported by The Scientific and Technological Research Council of Türkiye(T??B1TAK)with the project number 121C420。
文摘Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.
文摘This study addresses the challenge of predicting zinc(Zn)recovery from carbonate ores via sodium hydroxide(NaOH)leaching.This complex process influenced by variable ore composition,surface passivation effects,and nonlinear reaction dynamics,which complicate reagent optimization and process control in hydrometallurgical operations.To tackle this,a dataset containing 422 experimental observations was compiled from previous studies,incorporating ore composition and process parameters,such as NaOH concentration,leaching time,temperature,and solid-to-liquid ratio.Four regression models(decision tree,neural network,generalized additive model,and random forest)were trained and evaluated using performance metrics,such as coefficient of determination(R^(2)),root mean squared error(RMSE),mean absolute error(MAE),mean absolute percentage error(MAPE),and symmetrical mean absolute percentage error(SMAPE).Among these,the random forest model achieved the best predictive accuracy,with R^(2)value of 0.8541 on the test set and the lowest error rates,demonstrating its effectiveness in capturing the complex relationships between input variables and Zn recovery.Explainable artificial intelligence,particularly SHapley additive exPlanations(SHAP)analysis,revealed that NaOH concentration,leaching time,and solid-to-liquid ratio had the most positive influence on Zn recovery,whereas elements such as Ca,Fe,and Pb had inhibitory effects.These findings align with known geochemical behavior and provide valuable insights for reagent optimization and process effi-ciency in leaching processes.This study demonstrates the practical potential of machine learning in mineral processing,offering a scalable framework for optimizing Zn recovery from non-sulfide ores and a data-driven approach to enhance decision-making in hydrometallurgical applications.
基金funding from the National Natural Science Foundation of China(Nos.52478389 and 52525401).
文摘Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations to investigate mechanical behavior,fracture development,and energy evolution of CRF containing 54%aggregate content with three grain-size distributions(5-10,10-20,and 20-30 mm).Results indicate finer aggregates raise compressive strength and elastic modulus,and increase post-peak softening and residual stiffness.Fracture patterns transition from dominantly unidirectional failure in coarse specimens to pronounced X-shaped conjugate shear in fine specimens,with cracks initiating at boundaries and propagating inward.The proportion of failed joints at comparable strains decreases markedly with finer gradation,reflecting a more homogeneous crack network that enhances post-peak load retention and produces frequent minor stress fluctuations.Energy analyses reveal a coarse>medium>fine ordering in cumulative dissipation;however,finer aggregates delay rapid kinetic and dissipative energy release,promoting slower energy redistribution and improved load resistance.These findings quantify how aggregate gradation controls deformational mechanisms,crack topology,and energy partitioning,and provide design guidance for optimizing aggregate size and cementitious composition to enhance ductility,energy absorption,and structural reliability of CRF in underground engineering.
基金Alexander von Humboldt-Foundation (AvH) for the financial support as a research fellowthe financial support of the Scientific and Technological Research Council of Turkey (TüB_ITAK) under Project No. MAG-114M568
文摘Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.
文摘Mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion is used to deduce the stress redistribution around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method （BEM） was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the longwall panel. In velocity tomograms, the main zones of the stress redistribution arotmd the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the longwall mining panel continuously and subsequently to improve safety of mining operations.
文摘Prediction of surface subsidence caused by longwall mining operation in inclined coal seams is often very challenging. The existing empirical prediction methods are inflexible for varying geological and mining conditions. An improved influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, the original Knothe function has been transformed to produce a continuous and asymmetrical subsidence influence function. The empirical equations for final subsidence parameters derived from col- lected longwall subsidence data have been incorporated into the mathematical models to improve the prediction accuracy. A number of demonstration cases for longwall mining operations in coal seams with varying inclination angles, depths and panel widths have been used to verify the applicability of the new subsidence prediction model.
基金The research is supported by National Key R&D Program of China(No.2017YFC060300204)National Natural Science Foundation of China(No.52074293)+2 种基金Hebei Province Natural Science Foundation of China(No.E2020402041)Yue Qi Young Scholar Project,CUMTB and Yue Qi Distinguished Scholar Project(No.800015Z1138)China University of Mining&Technology,Beijing.
文摘In the Kaiping Coal field,mining of five coal seams,located within 80 m in the Kailuan Group,#5,#7,#8,#9 and#12 coal seam,is difficult due to small interburden thickness,concentrated stress distributions,high coal seam metamorphism,and complex geological conditions.By using the ZTR12 geological penetration radar(GPR)survey combined with borehole observations,the overburden caving due to mining of the five coals seams was measured.The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan,which provides a measurement basis for the control of rock strata in close multiple coal seam mining.For the first time,it was found that the overburden caving pattern shows a periodic triangular caved characteristic.Furthermore,it is proposed that an upright triangular collapsed pile masonry and an inverted triangular with larger fragments piled up alternately appear in the lower gob.The research results show that the roof structure formed in the gob area can support the key overlying strata,which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close coal seams.
基金sponsored by the Appalachian Research Initiative for Environmental Science(ARIES)
文摘Ground movements due to longwall mining operations have the potential to damage the hydrological balance within as well as outside the mine permit area in the form of increased surface ponding and changes to hydrogeological properties. Recently, the Office of Surface Mining, Reclamation and Enforcement(OSMRE) in the USA, has completed a public comment period on a newly proposed rule for the protection of streams and groundwater from adverse impacts of surface and underground mining operations(80 FR 44435). With increased community and regulatory focus on mining operations and their potential to adversely affect streams and groundwater, now there is a greater need for better prediction of the possible effects mining has on both surface and subsurface bodies of water. With mining induced stress and strain within the overburden correlated to changes in the hydrogeological properties of rock and soil, this paper investigates the evaluation of the hydrogeological system within the vicinity of an underground mining operation based on strain values calculated through a surface deformation prediction model. Through accurate modeling of the pre- and post-mining hydrogeological system, industry personnel can better depict mining induced effects on surface and subsurface bodies of water aiding in the optimization of underground extraction sequences while maintaining the integrity of water resources.
文摘The distribution of the final surface subsidence basin induced by longwall operations in inclined coal seam could be significantly different from that in flat coal seam and demands special prediction methods. Though many empirical prediction methods have been developed, these methods are inflexible for varying geological and mining conditions. An influence function method has been developed to take the advantage of its fundamentally sound nature and flexibility. In developing this method, significant modifications have been made to the original Knothe function to produce an asymmetrical influence function. The empirical equations for final subsidence parameters derived from US subsidence data and Chinese empirical values have been incorpo- rated into the mathematical models to improve the prediction accuracy. A corresponding computer program is developed. A number of subsidence cases for longwall mining operations in coal seams with varying inclination angles have been used to demonstrate the applicability of the developed subsidence prediction model.
基金The research work in this paper is financially supported by the West Virginia Coal and Energy Research Bureau(CERB).
文摘The broad objective of this research was to improve current surface mining practices and reduce negative environmental impact of overburden removal in West Virginia(WV).The specific objectives were to(i)compare conventional surface mining method(drilling,blasting,digging,and loading)to a surface miner(SM)method,and(ii)apply the analytical hierarchy process(AHP)to help select the optimal mining method based on production,cost and environmental criteria.The design and the procedures used in this research involve five interrelated modules:(i)rock properties of overburden in WV,(ii)drilling and blasting,(iii)digging and loading,(iv)SM method,and(v)comparative analysis and selection of the optimal mining method by AHP.Results of this research indicate that application of SM method would yield higher cost of overburden removal than conventional mining methods in rocks with a high unconfined compressive strength and abrasivity.A significant advantage of SM method,where applicable,is the elimination of the negative environmental impacts associated with blasting.
基金the support of the Maintenance Department of Mobin Co.Sungun Copper mine
文摘Equipment plays an important role in open pit mining industry and its cost competence at efficient operation and maintenance techniques centered on reliability can lead to significant cost reduction.The application of optimal maintenance process was investigated for minimizing the equipment breakdowns and downtimes in Sungun Copper Mine.It results in the improved efficiency and productivity of the equipment and lowered expenses as well as the increased profit margin.The field operating data of 10 trucks are used to estimate the failure and maintenance profile for each component,and modeling and simulation are accomplished by using reliability block diagram method.Trend analysis was then conducted to select proper probabilistic model for maintenance profile.Then reliability of the system was evaluated and importance of each component was computed by weighted importance measure method.This analysis led to identify the items with critical impact on availability of overall equipment in order to prioritize improvement decisions.Later,the availability of trucks was evaluated using Monte Carlo simulation and it is revealed that the uptime of the trucks is around 11000 h at 12000 operation hours.Finally,uncertainty analysis was performed to account for the uncertainty sources in data and models.
基金Funding for this research was provided by the National Institute for Occupational Health and Safety(NIOSH).
文摘Differential Interferometric Synthetic Aperture Radar(DInSAR),a satellite-based remote sensing technique,has application for monitoring subsidence with high resolution over short periods.DInSAR uses radar images to measure centimeter-level surface displacements.In the images,ground resolution can be relatively high,with each data point(pixel)representing the average displacement over an area of several square meters.The image data are acquired regularly which allows subsidence to be monitored sequentially over short periods;imaging periods typically range from weeks to months.Monitoring subsidence over short periods with high spatial resolution has potential to provide insight into the dynamics of subsidence and into relationships between mine advance and subsidence.In this study,for three longwall mines in the western United States,initial subsidence occurring at the start of longwall advance is quantified over short periods(12–72 days).C-band interferometric wide swath Synthetic Aperture Radar(SAR)images from the Sentinel satellites are used to quantify the subsidence.Overall,the data show initial development of subsidence,expansion of the subsidence trough,and the advance of subsidence in the direction of mining.
基金provided by the National Institute for Occupational Safety and Health,NIOSH(No.211-2014-60050)
文摘Most, if not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated from explosive gas zones(EGZs) in the longwall gob. Since 2010, researchers at the Colorado School of Mines(CSM) have studied EGZ formation in longwall gobs under two long-term research projects funded by the National Institute for Occupational Safety and Health. Researchers used computational fluid dynamics along with in-mine measurements. For the first time, they demonstrated that EGZs form along the fringe areas between the methane-rich atmospheres and the fresh air ventilated areas along the working face and present an explosion and fire hazard to mine workers. In this study, researchers found that, for progressively sealed gobs, a targeted injection of nitrogen from the headgate and tailgate, along with a back return ventilation arrangement, will create a dynamic seal of nitrogen that effectively separates the methane zone from the face air and eliminates the EGZs to prevent explosions. Using this form of nitrogen injection to create dynamic seals should be a consideration for all longwall operators.
文摘Longwall mining has a significant influence on gas wells located within longwall chain pillars.Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings.If the gas well casings are compromised or ruptured,natural gas could migrate into the mine workings,potentially causing a fire or explosion.By the current safety regulations,the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars.The current regulations for gas well pillar design are based on the 1957 Pennsylvania gas well pillar study.The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars.As the guidelines were developed for room-andpillar mining under shallow cover,they are no longer applicable to modern longwall coal mining,particularly,under deep cover.Gas well casing of failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study,conducted by the National Institute for Occupational Safety and Health(NIOSH),presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh Coal Seam.The study results indicate that overburden depth and pillar size are not the only determining factors for gas well stability.The other important factors include subsurface ground movement,overburden geology,weak floor,as well as the type of the construction of gas wells.Numerical modeling was used to model abutment pressure,subsurface deformations,and the response of gas well casings.The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above,within,and below the chain pillars,and the potential location and modes of gas well failures,thereby providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.
文摘Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs is proper machine inspection.Traditional miner safety training includes the use of hardcopy documents and video instructions.However,modern mobile and computer technology offers tremendous potential to improve the training process.In this study,we apply a 360-degree camera,opensource platform WordPress^(TM),and the software Unity3D in order to create materials and tools for the HEOs safety training to help trainees better understand the pre-shift safety machine inspection.The computer-based safety task training developed in this research is tested and implemented at a surface mine in the southern United States.
基金funded by the United Foundation key project fund,Chinese Natural Science Committee (No.U1261207)Datong Coal Group,Tashan Coal Mine,and supported by the Natural Science Foundation of Ningbo of China (No.U1261207)
文摘Coal seams in Tashan Mine of Datong Coal Group in China average 15 m thick and have been mined by the top coal caving longwall mining method of large mining height. Mining height was 3.8 m and the top coal caving height was 11.2 m. The gateroad pillar between panels was 38 m. During retreat mining,serious bumps occurred in the gateroads on both sides of the pillar affecting safety production. Therefore,pillarless mining was experimented. Using numerical modeling and comparative study of cases of similar mining condition,it was decided to employ a 6 m wide pillar,rather than the previous 38 m wide pillar.Support system for the gateroads was designed and implemented. During gateroad development,pillar failure conditions and entry deformation were monitored. Hydraulic fracturing method was employed to cut off the K3 sandstone along the entry rib so as to reduce the abutment pressure induced during retreat mining. Support reinforcement method combining grouting and advanced reinforcement methods was proposed to insure stable gateroad ahead of mining. Methane drainage and nitrogen injection were implemented to eliminate hazards associated with mine fire and spontaneous combustion. Since the development of gateroad has just completed,and retreat mining has not begun,the effectiveness of the proposed methods is unknown at this point. However,monitoring will continue until after mining.The results will be published in a separate paper.
文摘Mining method selection is the first and the most critical problem in mine design and depends on some parameters such as geotechnical and geological features and economic and geographic factors. In this paper, the factors affecting mining method selection are determined. These factors include shape, thick- ness, depth, slope, RMR and RSS of the orebody, RMR and RSS of the hanging wall and footwall. Then, the priorities of these factors are calculated. In order to calculate the priorities of factors and select the best mining method for Qapiliq salt mine, Iran, based on these priorities, fuzzy analytical hierarchy process （AHP） technique is used. For this purpose, a questionnaire was prepared and was given to the associated experts. Finally, after a comparison carried out based on the effective factors, between the four mining methods including area mining, room and pillar, cut and fill and stope and pillar methods, the stope and nillar mining method was selected as the most suitable method to this mine.
基金sponsored by the Alpha Foundation for the Improvement of Mine Safety and Health, Inc
文摘‘‘Web ground control"(web GC) provides users with instantaneous access to mine design applications anywhere, at any time, through a web browser.Utilizing a web-based multiple-tier architecture, users are able to easily access ground control designs, perform on-demand calculations in the field, as well as facilitate project collaborations across multiple users, devices, and operating systems.Currently, the web GC platform contains five ground control related design applications previously developed and distributed by the US National Institute of Occupational Safety and Health(NIOSH), that is, analysis of roof bolt stability(ARBS), analysis of longwall pillar stability(ALPS), analysis of retreat mining stability(ARMPS), analysis of retreat mining stability–highwall mining(ARMPS-HWM), and analysis of horizontal stress in mining(AHSM).With respect to design decisions made by the web GC development team, the web GC platform will be able to further integrate future mine design applications providing the mining industry with one of a kind umbrella suite of ground control related software available at ones fingertips.The following paper provides a detailed overview on the current state of the web GC platform with discussions ranging from back-end database development and design to the front-end user-platform interface.Based on current progress in platform development as well as beta testing results, the web GC platform is scheduled for release in the fall of 2018.
