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Multi-criteria decision evaluation of coal gangue resource utilization schemes: A case study of the taigemiao mining area
Calculation method of sectional velocity and coal flow based on discrete element simulation for scraper conveyors
Process optimization and mechanism study of cementitious material prepared from coal gangue via hydrothermal-calcinations synergistic activation
Fiber-reinforced composite round link chains for scraper conveyors: opportunities and challenges
New advances in in-situ simulation test technology for cemented paste backfill and its mechanical response characteristics
more..Effect of water saturation on the mechanical and ultrasonic response of cemented tailings backfill
Wu Weilv; Ji Sigang; Su Naxian; Zhan Jie; Tang ZixvThe strength assessment of cemented tailings backfill (CTB) in undergroundstopes is a focal point of current research. However, revealing the "black box"inside underground stopes remains challenging because of variable drainageand curing temperature conditions, which governs strength variation throughthe intermediate parameters of pore water saturation and hydration degree.In this study, ultrasonic pulse velocity (UPV) measurements, X-ray computedtomography (CT), and water retention curves were integrated to examineunconfined compressive strength (UCS) and UPV evolution with changingwater saturation, and to analyze the correlations among these parameters.The results indicate that while water saturation significantly affects UPV, itsinfluence on UCS is relatively minor. Both UPV and UCS increase as the connectivityof the solid phase increases, and the relationship of UPV and UCS canbe fitted by an exponential function. Finally, a new insight is provided that theprediction accuracy of the UPV–UCS evolution model of CTB can be furtherimproved by accounting for the water saturation. This research contributes tounderstanding the propagation mechanism of ultrasonic waves in unsaturatedCTB, and offers a feasible approach for predicting CTB strength and mitigatingpotential geotechnical hazards in underground stopes.
Characterization of acoustic-electrical response of raw coal with different moisture content under uniaxial cyclic loading and unloading
Peng Chen; Shibo Yu; Hui Wang; Zhixiu Wang; Zhihuai Li; Nan LiMoisture content and cyclic loading critically control the mechanical behaviorand failure evolution of coal in deep multi-seam mining. Acoustic emission(AE) and electrical resistivity methods are widely used to monitor load-induceddamage and identify fracture precursors. Here, we perform uniaxial cyclicloading–unloading tests on raw coal under dry, saturated, and natural moistureconditions. Acoustic and electrical signals are synchronously recorded.We investigate the acoustic-electrical response and fracture precursor characteristicsunder varying moisture contents. The results show that acousticand electrical signals are strongly correlated with stress throughout cyclicloading–unloading. Cumulative AE parameters increase stepwise with loadingcycles. Different loading stages display distinct acoustic-electrical responses.Both signals surge abruptly at the moment of fracture. We find that moisturecontent significantly modulates the acoustic-electrical response. AE signalsare attenuated, while coal conductivity is enhanced with increasing moisture.These findings provide theoretical and technical support for damage monitoring,fracture early warning, and safe extraction of water-bearing coal at depth.
Integrated backfill planning for sustainable closure of opencast coal mines in India: Case studies and innovative decision support framework
Pritam Biswas; Phalguni SenOpencast (OC) mining dominates global coal production, accounting for morethan 95% of India's coal output. While this method is highly productive, itresults in substantial mining voids, significant overburden, and extensive landdisturbance, making closure planning a major techno-economic and environmentalchallenge. Although backfilling is commonly used as a mitigationmethod, planning is frequently prioritized by production objectives overclosure viability. As finite resources and ecological concerns become moreapparent, the mining industry must adopt and practice sustainable miningtechniques to protect the environment and manage resources responsibly. Thiswork presents a strategic integrated backfill planning decision supportframework (IBP-DSF) for the sustainable closure-oriented planning of OC coalmines. The IBP-DSF integrates block geometry, material availability, depthof pit, hydro-environmental sensitivity, geotechnical stability, and economicfeasibility into a dimensionless integrated backfill planning score (IBPS) usingnormalized indices and weighted aggregation. Based on defined thresholdranges, the IBPS classifies mines into four closure strategies: complete backfilling,partial backfilling with void optimization, engineered voids or controlledwater bodies, and external dump dependency. The framework is applied tobrownfield and greenfield Indian OC coal mines, supplemented by hypotheticalboundary scenarios. Results indicate that complete backfilling is feasible onlywithin a limited operational envelope, whereas partial backfilling and optimizedvoid management provide more practical and sustainable closure solutionsunder most conditions. The proposed model offers a transparent, transferable,and scalable decision-support tool to guide realistic closure planning, optimizeland use, and reduce long-term environmental, financial, and social risks.
LSTM learning enhanced deep cone thickening and paste backfilling for high density tailings: A case study
Ruiming Guo; Bolin Xiao; Jun Nie; Aixiang Wu; Jiandong Wang; Min LiuPaste backfill relying on deep-cone thickening represents a complex systemsengineering challenge. Achieving stable thickening, consistent paste quality,and efficient process control remains a critical challenge for the metal miningindustry. Recent advances in computational intelligence offer new opportunitiesto improve system efficiency and operational stability. Using data from aMongolian zinc mine with high-specific-gravity tailings (SG = 3.459), this studyproposes a multivariate long short-term memory (LSTM)-based predictivemodel for underflow concentration. Leveraging historical data on four key variables,the model employs a sliding-window mechanism to perform recursivethree-hour-ahead forecasts of underflow concentration. The model achievedhigh training accuracy (coefficient of determination (R2) = 0.92) and robusttest performance (mean absolute error (MAE) = 0.42% and root mean squarederror (RMSE) = 0.48%), confirming its suitability for engineering applications.Simulations under three discharge rates (40, 50, 60 m3/h) indicated that solelymaximizing discharge rate is suboptimal. Accordingly, a "predicting–evaluating–regulating" feedforward control framework is proposed, shifting operationsfrom reactive feedback to proactive regulation. Industrial trials maintained aslurry bed height of approximately 5.5 m. Proactive discharge-rate regulationsustained underflow concentration at 70%–82% for 7 h, enabling consistentpreparation of high-quality paste (74%–76% solids content). In the stope, thebackfill provided sufficient bearing capacity for personnel access within 10 h at low cement-to-tailings ratios, achieving 1.5 MPa after one day and exceeding 3 MPa after three days at higherratios. The proposed predictive model offers a quantitative tool and a methodological pathway for optimizingdischarge strategies and facilitating feedforward control in deep-cone thickening.
A critical review of critical metals in coal and coal-bearing strata: Characteristics, enrichment mechanisms, extraction techniques, and strategic significance
Peidong Su; Haocheng Ye; Bin Li; Zhiyu ZhangCritical metals are pivotal to the global energy transition and modern high-techindustries. As conventional ore reserves face growing supply chain vulnerabilities,coal measures are increasingly recognized as promising unconventionalreservoirs for essential elements, particularly lithium (Li), gallium (Ga),germanium (Ge), and rare earth elements (REEs). This paper systematicallysummarizes the occurrence patterns, mineralization drivers, recovery methodologies,and geopolitical value of these strategic resources within coal-bearingformations. The enrichment of these metals is shown to be controlled bycomplex geological processes, including sedimentation, magmatism, andhydrothermal activities, with material sources varying from terrigenous clasticsto deep-seated fluids. Furthermore, this paper critically evaluates currentextraction methodologies, including physical beneficiation, chemical leaching,and bioleaching. While physical methods offer low costs, their efficiency islimited by the complex occurrence modes of metals. Chemical leaching ensureshigh recovery but faces environmental challenges, whereas bioleaching is ecofriendlyyet slower. Ultimately, advancing eco-friendly, highly efficient, andsynergistic extraction systems is crucial for maximizing the value of coal-basedresources and safeguarding domestic mineral supply chains.
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