Engineering

Abstract: In open-pit optimization software, metallurgical recovery is commonly treated as a constant for every block, although it varies with ore type and grade. Here, recovery is modelled as a block-grade-dependent variable using 24 laboratory flotation tests on the sulfide ore of a copper deposit in eastern Türkiye, and its effect on net present value (NPV) and the cut-off grade decision is examined. The deposit is split by sulfur content into two routes: sulfide ore (S ≥ 9%) to flotation and oxide ore (S < 9%) to heap leaching. Across a feed grade of 0.22–6.99% Cu, the measured recovery increases with feed grade from about 61% to 94%; the linear correlation is only moderate (r = 0.60), but the relationship is well described by a bounded, saturating recovery–grade curve (R(g) = R_max•g/(g + k); R_max = 0.95, k = 0.12; R² = 0.87). For the leach route, where no test data are available, a fixed 80% recovery is retained throughout. Optimization I (fixed recovery) and Optimization II (variable recovery on the sulfide route) are compared over ten scenarios, using a slope-constrained ultimate pit (50° overall slope, 5% discount rate). Because the deposit's copper is concentrated in high-grade sulfide blocks with measured recovery of about 90–93%, the metal-weighted recovery of the sulfide ore is 88.9%, and the fixed 80% assumption underestimates both recoverable copper and NPV. Under a fixed pit and cut-off, variable recovery yields roughly 8% higher NPV and about 2.9 kt more copper. When the cut-off grade is instead determined economically, variable recovery reclassifies the marginal low-grade sulfide ore (~0.05 Mt, measured recovery below 80%) as uneconomic; even so, total copper output rises from 40.2 kt (fixed) to 43.0 kt (variable) — a slightly smaller gain, because this marginal ore is excluded. Grade-dependent recovery derived from laboratory data thus determines both the recoverable metal and the marginal-ore boundary more realistically than a fixed assumption, and materially affects NPV for this deposit.

Abstract: Acoustic Emission (AE) measurements have many uses to evaluate the integrity of mate-rials. AE is often used to detecting leakage in pipelines. It has also been used to monitor changes in strength properties of fiber reinforced concrete. In the oil and gas industry, AE is predominantly used to study fracture initiation and propagation. In particular, charac-terization of samples is key for evaluating subsurface formations for successful under-ground storage. Research has been done to understand the behavior of AE in uniaxial compression and single stage triaxial compression tests. However, the validity of this method has not been documented in a multistage triaxial test. This characterization is required to understand the stability of the host rock under the related stress changes and potential mineralogic changes which may occur. Typically, there is a shortage of geolog-ic samples. A single multistage triaxial test eliminates the need for twin samples and provides an economic and time saving protocol compared to conventional methods. A single multi-stage triaxial (MST) test allows a constitutive model to be developed for a host rock. This work establishes a protocol for performing these tests with minimal correc-tions to the measurements. Acoustic Emissions were measured on five different samples undergoing Multi-stage Triaxial Tests. Two different behaviors were observed. For the “coarse grained” samples, designated Group 1 (Miocene sandstone, Wilcox and Cambri-an sandstone), the number of AE events did not show a strong dependence on confining stress. They did show an exponential increase of AE events with increasing deviatoric stress during each stage. In contrast, the Group 2 samples (Niobrara Marl and Niobrara Chalk) exhibited a significantly different stress dependent AE behavior. The amplitude of the AE events is significantly smaller than the quartz dominated samples indicating a more ductile and diffuse failure mechanism. The correction between maximum compres-sive strength and the point of positive dilatancy is still 1.2 for these samples, even though a different pattern of AE events is observed.

Abstract: This study examines the impact of regrinding on the interfacial properties of sulfide minerals and the flotation performance of weathered copper-porphyry tailings. The feed material is characterized by a low copper grade (0.17%) and a high proportion of oxidized species (53.84%), which contributes to its inherent chemical stability and poor flotation kinetics. The findings indicate that regrinding serves a dual role: facilitating the liberation of mineral intergrowths and inducing mechanical surface renewal. This renewal is characterized by a significant decrease in the oxidation-reduction potential (ORP) and an intensification of the surface reactivity. Experimental results identify an optimal grinding fineness of 77-81% passing -0.045 mm, yielding a copper recovery of 16.26% in the absence of a sulfidizing agent. The integration of sodium sulfide (400 g/t) with regrinding significantly enhances recovery to 36.37%, driven by the establishment of a reducing environment (ORP ≈ -150 mV) and the chemisorption-mediated activation of mineral surfaces. While ultrafine grinding (90-100% passing -0.045 mm) further increases recovery to 51.47%, it is accompanied by deleterious sliming effects and a subsequent loss of process selectivity. The study confirms that mechanical surface rejuvenation and the optimization of electrochemical conditions are critical for improving the processing efficiency of anthropogenic resources. providing a theoretical framework for establishing rational beneficiation regimes.

Abstract: The loess gully region is characterized by complex terrain with crisscrossing gullies,where coal mining can readily induce surface subsidence and slope deformation. Such deformation often leads to geological hazards and ecological issues,including collapses,landslides, soil erosion, vegetation dry up,and land degradation.Therefore,understanding the deformation behavior of mining‑induced slopes is essential for the restoration and management of mine geological environments.This study focuses on five slopes within working faces 50205 and 50206 of the Zhen’er Coal Mine in Fugu County.Using a combination of 3DEC numerical simulations and orthophoto-based fracture identification, we systematically investigated mining-induced slope deformation under the complex topographic conditions of the loess gully region.The goal is to answer three key questions: where mining-induced slope deformation primarily occurs,how it evolves over time, and what the main controlling factors are.Spatially,the primary deformation zones and their propagation paths vary significantly among the five slopes.The largest deformation occurs in the slope body directly above the main section of the working face,gradually decreasing toward the edges of the working face. Temporally, mining-induced slope deformation exhibits a time lag, meaning that surface responses lag behind underground mining activities and continue to develop even after the working face is fully extracted.In the loess gully region, slope deformation induced by mining is controlled not only by mining activities but also by topographic factors such as slope shape, aspect,gradient, and height. The spatiotemporal evolution of deformation becomes even more complex for slopes that span multiple working faces. These findings provide a scientific basis for monitoring mining-induced slope deformation and preventing geological disasters in the loess gully region,while also offering practical guidance for safe mining operations and hazard control in similar settings.

Abstract: Autonomous Haulage Systems (AHS) have significantly transformed surface mining operations by improving safety, productivity, and operational consistency. Currently, implementations predominantly rely on vehicle-centric perception architectures. Onboard LiDAR, radar, cameras, and Global Navigation Satellite Systems (GNSS) perform sensing, interpretation, and decision-making in individual systems. Decision-making is done using onboard LiDAR, radar, and cameras, and Global Navigation Satellite Systems (GNSS) in individual systems. These approaches enable collision avoidance and path tracking. They remain limited in their ability to account for the broader, dynamic mining environment characterized by dust, terrain degradation, geotechnical instability, heterogeneous traffic, and rapidly evolving operational conditions. This paper presents a systematic review of dynamic vision systems deployed in surface mining. It critically analyses the transition from solitary vehicle autonomy to interconnected, ecosystem-aware intelligence. The review synthesizes literature from mining automation, robotics, intelligent transportation systems, and multi-agent perception. This is to assess sensing technologies, perception algorithms, sensor fusion strategies, and environmental robustness techniques. Attention is given to the limitations of ego-centric perception models in complex open-pit ecosystems. Building on identified gaps, the paper proposes a conceptual framework for Ecosystem-Centric Dynamic Vision (ECDV). This perception is augmented through integration with fleet communication networks, dispatch systems, digital twins, geotechnical monitoring platforms, and environmental sensing infrastructure. The framework outlines a multi-layer architecture enabling cooperative perception, predictive hazard modeling, and risk-aware decision support at the mine-wide level. The review concludes by defining a research agenda for transitioning from vehicle autonomy to ecosystem intelligence in surface mining. It highlights opportunities in cooperative perception, adaptive sensor fusion under degraded visibility, and digital twin integrated predictive safety systems.

Abstract: Autonomous Haulage Systems (AHS) have become increasingly important as mining operations seek to improve productivity and remove workers from hazardous environments. The systematic integration of this technology requires not only operational change management but also a deeper understanding of mine-planning implications. Existing literature describes AHS and implementation guidelines with a focus on operational safety and autonomous system architecture, but it does not systematically address required planning-level adaptations. This study aims to identify how surface mine planning frameworks must evolve to accommodate autonomy in open-pit metal mining operations. A systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, with emphasis on identifying the principal aspects of AHS that must be considered in mine-planning strategies. Findings reveal major shifts in workforce dynamics, communication infrastructure, and haul road geometry, and show that road-width and load-channelization questions remain site-specific research needs rather than settled design rules. The study highlights the need for (i) mine-planning frameworks that treat AHS as a constraint on pit geometry, haul-road structural and functional design, fleet selection, production scheduling, roadmaintenance strategy, economic and social evaluation; (ii) human-systems integration and improved human-autonomous collaboration; and (iii) empirical validation of workforce transition strategies for more effective and safe deployment.

Abstract: Natural lateral particle segregation commonly occurs during the hydraulic deposition of slurry and thickened tailings in surface tailings storage facilities (TSFs), producing spatial heterogeneity in physical, hydrogeotechnical, and mineralogical properties, as well as in the water table. In sulfide-rich tailings, such heterogeneity complicates the design of reclamation cover systems, which are themselves affected by it. This study investigates the impact of physical and rheological properties of hard-rock mine tailings slurries on their segregation under hydrodynamic conditions. It proposes a multiparametric equation for the segregation index (SI) based on Buckingham's π-theorem. For this purpose, six flume experiments were conducted using tailings with initial solids mass concentrations of 63%, 66%, and 69% at slopes of 0.5% and 1%. Results revealed strong exponential correlations (R² > 0.95) between SI and tailings' physical properties (solids concentration, bulk density) as well as rheological parameters (Herschel–Bulkley yield stress and flow index, Cross infinite dynamic viscosity). The SI equation was developed using MATLAB nonlinear least-squares optimization with a trust-region reflective algorithm. Using an SI threshold of 0.05 to define non-segregating behavior, the proposed model can predict segregation tendencies as a function of tailings properties and slope conditions. Further laboratory and field investigations are needed to validate and generalize the criterion.

Abstract: Turbulent drag reduction (DR) using polymers is a critical technique for energy conserva-tion in fluid transport systems. Traditional monitoring methods relying on pressure transducers are intrusive and lack real-time turbulence characterization. This study pro-poses a novel non-intrusive intelligent monitoring system based on Fiber Bragg Grating (FBG) sensing and Artificial Intelligence (AI). An experimental setup was constructed to investigate the DR performance of polymer solutions. FBG sensors were utilized to capture the optical spectrum shift induced by turbulent flow fluctuations. A deep learning model was trained to correlate the optical signal features with the drag reduction rate. Results demonstrated that the AI model achieved high prediction accuracy (R² > 0.95), effectively replacing complex fluid dynamic calculations with optical signal analysis. This work provides a promising approach for real-time, non-intrusive monitoring of fluid flow characteristics in industrial applications.

Abstract: Chalcopyrite and molybdenite exhibit similar surface wettability and high floatability, which has long hindered their efficient and selective separation in mineral processing. In this work, the novel chalcopyrite depressant 2-mercapto-5-benzoimidazole sulfonate dihydrate (2MBI5SA) was investigated for its effect on the flotation behavior of chalcopyrite and molybdenite. Compared with the conventional depressant sodium sulfide (Na₂S), 2MBI5SA exhibited stronger selective depression toward chalcopyrite; under conditions yielding Mo recovery of 81.46% and a Mo grade of 4.46%, the Cu recovery decreased to 13.03%. To clarify the origin of this selectivity, interfacial properties were systematically characterized using adsorption measurements, contact angle measurements, zeta potential measurements, FT-IR, XPS, and SEM-EDS, and the adsorption mechanism was further elucidated using SCC-DFTB calculations. The results demonstrate that 2MBI5SA chemisorbs onto the chalcopyrite surface via bidentate coordination, forming a stable adsorption layer that effectively suppresses chalcopyrite flotation. Moreover, structure-function relationship analysis confirmed that introducing hydrophilic and ionizable functional groups into the collector framework can convert a collector into a selective depressant, thereby providing new insight into the design of environmentally benign flotation depressants.

Abstract: The flotation of oxidized lead–zinc ores presents a significant challenge due to the low floatability of oxidized minerals and their weak interaction with conventional reagents. This study investigates the influence of the electrochemical parameters of the pulp (redox potential, Eh, and pH) on the flotation kinetics of oxidized lead–zinc ore from the Koskuduk deposit. It was established that the use of sodium sulfide Na₂S leads to the selective activation of lead-bearing minerals (Pb recovery up to 40.74%) with low zinc recovery (~12%). The use of a polysulfide-lime system S:CaO:H₂O is proposed, providing more uniform and stable sulfidization of the mineral surface. It is shown that the application of this reagent increases recovery to 65.10% for lead and 56.89% for zinc. It was established that the maximum recoveries are achieved within an Eh range of -120 to -180 mV at pH 11-12. Kinetic studies demonstrated that the main contribution to metal recovery occurs within the first 2-6 minutes of flotation. The obtained results indicate that flotation efficiency is determined both by the type of reagent and by the electrochemical state of the pulp, and that the use of polysulfide systems represents a promising approach for the processing of oxidized lead-zinc ores.

Abstract: Progressive slope failures in open pit mining are characterized by accelerating deformations that can be monitored and potentially forecast. While current monitoring practice emphasizes velocity-based parameters and the inverse velocity method for failure prediction, the role of acceleration in understanding failure mechanisms and improving early warning systems remains underexplored. This paper presents a conceptual and analytical framework for characterizing acceleration in progressive slope failures. We introduce the concept of slope damage as a cumulative measure of positive accelerations over time, and demonstrate its utility in identifying the Onset of Acceleration (OOA), defined as the critical transition from regressive to progressive failure. We further examine the geotechnical conditions necessary for the inverse velocity method to be valid, proposing that a fully or nearly fully mobilized failure surface is required for sustained acceleration. The distinction between hazard-relevant velocity exceedance and failure-indicative progressive acceleration is discussed in the context of Trigger Action Response Plan (TARP) frameworks. This work contributes to the fundamental understanding of progressive failure mechanisms and provides practical guidance for acceleration-based slope monitoring.

Abstract: To address the challenge of separating fine-grained apatite from layered silicate gangue minerals (chlorite and biotite) in medium-low grade collophanite ores, this study systematically investigated the effect of carboxymethyl cellulose sodium (CMC-Na) as a selective depressant on flotation behavior of different particle size fractions and its underlying mechanism. Pure mineral and artificial mixed ore flotation experiments demonstrated that at pH 9 and collector dosage of 5 kg/t, CMC-Na enabled selective separation of apatite from gangue minerals, with optimal dosage showing significant particle size effects: for the -0.5+0.074 mm fraction, effective separation was achieved with collector alone; for the -0.074+0.023 mm fraction, the optimal CMC-Na dosage was 10~100 mg/L, yielding 87% apatite recovery for pure minerals and 41.8% recovery with 23.7% P₂O₅ grade for mixed ores; for the -0.023 mm fine fraction, the optimal dosage was 30~300 mg/L, achieving 24.8% recovery and 13.2% grade. Mechanism studies revealed that CMC-Na significantly enhanced the hydrophilicity of chlorite and biotite, enlarging their surface property differences with apatite. FTIR and XPS analyses indicated that CMC-Na adsorbed on biotite via ion exchange with interlayer K⁺ and coordination with octahedral Fe²⁺/Mg²⁺, and on chlorite through chemical coordination with octahedral Mg²⁺, whereas only weak physical adsorption occurred on apatite surface Ca²⁺. The adsorption strength followed the order: biotite > chlorite > apatite. This study provides an effective reagent scheme and theoretical basis for flotation separation of fine-grained phosphate ores.

Abstract: The application of multi-branch pinnate drilling has great prospects in gas control. Although there are many studies on the parameters of multi-branch plume drilling, the mathematical model used in the study is still not sufficient for the addition of the slippage effect and thermodynamic changes. In this paper, a thermal–fluid–solid coupling model is used to study the influence of branch angle and branch length on the extraction effect in high-gas and extra-thick coal seams. The reliability of the model is verified by simulating an onsite extraction environment to fit the onsite gas production rate. Under identical simulation conditions, the experiment investigated the gas extraction performance of boreholes with varying branch angles (30°, 40°, 50°, and 60°) and branch lengths (50 m, 75 m, 100 m, and 125 m). The results show that temperature affects the dynamic viscosity of gas, which in turn affects the flow rate. The slippage effect affects permeability. When the branch angle is less than 50°, the increase in the branch angle can expand the control range of drilling. By continuing to increase the angle, the improvement in the extraction effect is weakened. As the branch angle exceeds 50° and continues to increase, the branch borehole progressively approaches the edge of the coal seam. At this time, the overall control range of the borehole is greatly increased, and the gas extraction effect is improved. The increase in the branch length leads to a considerable improvement in the extraction effect. When the branch length is below 100 m, the improvement in extraction efficiency diminishes progressively with increasing branch length. This is because the effect of increasing the branch length on improving the overall control range of the borehole is weakened. When the branch length exceeds 100 m and continues to increase, the branch borehole approaches the edge of the coal seam. The overall control effect of drilling has been greatly improved. The extraction effect of boreholes has increased significantly compared with before.

Abstract: Accurate characterization of rock mechanical parameters in heterogeneous geological formations remains fundamentally challenging because lithological heterogeneity induces mapping ambiguity: similar logging responses may correspond to different mechanical properties. Existing approaches, including empirical formulas, pure machine learning models, and feature-augmented learning methods, generally assume a single global mapping between logging data and geomechanical response, which limits their ability to resolve heterogeneity-induced bias. To address this issue, this study proposes a heterogeneity-aware residual learning framework for rock mechanical parameter characterization from well logs. Rather than treating lithotype information as a simple auxiliary feature, the method explicitly models lithotype-dependent deviations as structured conditional corrections to the global geomechanical response. In this way, heterogeneity is represented as a learnable source of systematic bias rather than being implicitly absorbed into a single global predictor. The proposed framework is potentially extendable to other heterogeneous subsurface systems and applicable to heterogeneous geological systems where conditional bias exists. By explicitly accounting for lithology-controlled response deviations, it alleviates the non-uniqueness caused by heterogeneity and improves the physical consistency of prediction. Cross-well validation demonstrates that the proposed method effectively reduces lithotype-induced bias and achieves stable generalization under varying geological conditions. Further analysis shows that the performance gain does not arise from additional information alone, but from structural modeling of conditional bias under heterogeneous lithological regimes. This study provides a generalizable modeling paradigm for geomechanical characterization in heterogeneous subsurface systems and offers a physically consistent basis for reliable prediction in complex geological environments.

Abstract: To investigate the interaction between mine ventilation and the thermal en-vironment in a fully mechanized longwall face, a Computational Fluid Dy-namics (CFD) model was developed for the 11-3107 working face of Menkeqing Coal Mine based on field-measured data. The model was used to analyze the effects of ventilation mode, electromechanical equipment layout, roadway length, airflow velocity, and inlet air temperature on the thermal environment of the working face. The results show that changing the ventilation mode alone has only a limited effect on reducing the maximum face temperature, although the U-shaped system provides a comparatively practical ventilation arrange-ment under the studied conditions. Locating major electromechanical equipment in the return airway helps reduce the temperature in the intake airway and working face. Shorter ventilation routes, higher airflow velocity, and lower inlet air temperature all contribute to improved thermal conditions. Considering both simulation results and operational constraints, cooling equipment should be installed near the intake airway to effectively lower the working-face temper-ature. Based on psychrometric analysis and ventilation parameters, the required cooling load for the 11-3107 fully mechanized working face was determined to be 2417 kW under normal conditions and 3082 kW under critical conditions, in-cluding a 20% safety margin. The study provides a numerical basis for venti-lation optimization, cooling-system design, and heat-hazard control in deep underground coal mines.

Abstract: Maintaining the integrity of waterproof strata (WPS) between mine workings and overlying aquifers is critical, because water-conducting cracks (WCC) may cause mine flooding and surface subsidence. In the Upper-Kama potash deposit, the WPS is a 50-140 m thick stratified sequence of evaporites and clays overlying mined-out cham-bers. Under long-term loading, salt rocks tend to creep, soften, and localize damage, which can cause WPS failure. In this paper the Concrete damage-plasticity model, supplemented by the N2PC-MCT viscoplastic creep model, is applied to simulate WCC initiation and evolution in the Upper-Kama WPS. Model parameters are obtained from published laboratory tests, in-cluding uniaxial and triaxial compression and tension, and then validated using ob-served ground-surface subsidence. A plane-strain finite-element model incorporates stratified lithology, interface elements between layers, and stepwise excavation. Long-term simulations up to 50 years investigate two operational scenarios: with and without backfilling. The calibrated model reproduces the main stages of surface subsidence and chamber closure. Without backfilling, simulations indicate that tensile damage localizes mainly in a stiff central salt layer of the WPS. Most cracks appear approximately between 33 and 37 years after the beginning of mining. With backfill, tensile crack propagation stops and damage remains stable. A hypothetical homogeneous WPS case confirms that the observed central-layer cracking is associated with stiffness contrasts and composite bending in the stratified system. An approximate analytical multilayer beam solution, based on energy minimization, predicts bending stress concentration in stiff intermediate layers and is consistent with the numerical stress distribution. The combined numerical and analytical results clarify the mechanisms of long-term WCC initiation in stratified WPS and may be used for hazard assessment and planning of mitigation measures, including backfilling and focused monitoring of stiff central layers.

Abstract: Artisanal and illegal gold extraction in ecologically sensitive tropical landscapes can generate persistent environmental damage and public fiscal liabilities that accumulate even under formal mining prohibitions. A decision-grade pipeline is presented that converts observable environmental signals into (i) spatial prioritization surfaces, (ii) phase-timed remediation portfolios, and (iii) present-value (PV) comparisons of legislative policy pathways under uncertainty, demonstrated for the Crucitas mining landscape (Cutris, northern Costa Rica). Five linked models are implemented. Remote-sensing change proxies are derived using consistent baseline (January 2019–December 2020) and recent (February 2024–January 2025) windows; multi-criteria indices then produce a 0–100 grid-cell prioritization surface integrating land, water, and hydrologic dimensions. This prioritization output is translated into a phased remediation portfolio across 1,324 costed grid cells, yielding a gross liability of US$548.0 million (10-year PV; 5% discount rate). PSA-related credits total US$167.3 million PV; enforcing a cell-level non-negativity floor yields a baseline net PV of US$408.0 million (simple gross-minus-credits would be US$380.8 million). Deterministic policy overlays produce policy-adjusted net PV of US$336.1 million under Exp. 24.717 (minimum 5% royalty case; Δ = −US$71.9 million vs baseline; modeled royalty PV = US$93.8 million), US$503.0 million under Exp. 24.675 (Δ = +US$95.0 million), and US$510.3 million under Law No. 8904 (Δ = +US$102.3 million). Royalty-rate sensitivity cases for Exp. 24.717 yield deterministic policy-adjusted net PV of US$242.3 million (10%) and US$148.5 million (15%). Monte Carlo propagation yields a right-tailed baseline distribution (P10–P90 = US$385.4–519.1 million; P50 = US$450.1 million), with exceedance probabilities P(>US$400 million) = 0.8357 and P(>US$500 million) = 0.1786. Policy-adjusted uncertainty bounds indicate substantially reduced exceedance risk under Exp. 24.717 (5% royalty case; P(>US$400 million) = 0.3542; P(>US$500 million) = 0.0153), with further reductions at higher take-rates (10%: P(>US$400 million) = 0.0375; P(>US$500 million) = 0.0007; 15%: P(>US$400 million) = 0.0028; P(>US$500 million) = 0.0000), while non-mining pathways shift the distribution upward. The results support PV-consistent, uncertainty-aware ranking of contested pathways, with outcomes conditional on enforceable offsets, credible enforcement effectiveness, and residual-risk provisioning. The framework is transferable to other contested mining landscapes where phased interventions and policy alternatives require fiscally comparable evaluation.

Abstract: The use of flotation reagents in the form of microemulsions significantly enhances the recovery of noble metals during the flotation of gold-bearing ore and technogenic materials by improving the hydrophobicity of finely dispersed sulfides. This study in-vestigates the effect of a microemulsified dibutyldithiophosphate (DBDTP) on the flo-tation performance of gold-bearing ore and technogenic materials. The research objects were gold-bearing ore and aged flotation tailings from a Kazakhstani deposit contain-ing 3.43 g/t and 0.62 g/t of gold, respectively. Flotation beneficiation was conducted using a microemulsion of DBDTP generated in WAMG. Flotation kinetics demonstrat-ed that the application of the DBDTP microemulsion accelerates the flotation process, increasing gold recovery by 4.65% and reducing gold content in flotation tailings by 0.17 g/t. Under the baseline regime, 37.51% of gold is distributed into the −0.025+0 mm size fraction of tailings with a gold grade of 0.98 g/t. When the microemulsion reagent produced by the WAMG is applied, gold distribution in the −0.025+0 mm size fraction decreases to 28.29% (9.22% lower than the baseline), with a gold grade of 0.62 g/t. In the flotation of aged tailings, the microemulsion application increases gold recovery in the concentrate by 5.88% while maintaining concentrate quality.

Abstract: Longwall paste backfilling mining is severely restricted in large-scale application due to its sequential mining-isolation-backfilling-curing operation mode, which leads to low production efficiency and poor economic feasibility. Taking the E1302-B paste backfilling face of Gaohe Coal Mine as the engineering background, this study systematically identified the key efficiency-restricting factors including low isolation efficiency, cumbersome backfilling process, prolonged paste curing time and insufficient system operation controllability, in view of the complex geological conditions of the face such as severe undulation of roof and floor and irregular cross-section. Technological innovations were carried out from four core dimensions: high-efficiency isolation, high-efficiency backfilling, accelerated curing and intelligent safety control. A self-adaptive mechanized isolation device was developed, a high-efficiency backfilling process with simplified isolation procedures was proposed, the optimal accelerator addition method with cross-blade mixing was determined, and an integrated intelligent monitoring system covering the whole process of equipment-pipeline-support was constructed. Eventually, a high-efficiency integrated technology system for longwall paste backfilling mining was formed. Industrial test validation demonstrated that the technical system significantly boosts the efficiency of isolation, backfilling and solidification in the backfill mining cycle, cutting the time of a single backfill mining operation cycle by 57%. The annual production capacity of the E1302-B face was increased to 0.81 Mt, with a comprehensive backfilling mining cost of 466.63 CNY/t, an annual economic benefit of 108.03 million CNY and a static investment return rate of 48.96%. The E1306 face achieved an even higher annual production capacity of 1.12 Mt with a static investment return rate of 74.94%. This technology system effectively breaks the efficiency and economic bottlenecks of traditional longwall paste backfilling mining, realizes the dual improvement of backfilling mining efficiency and economic benefits, and provides technical support and practical approaches for the large-scale application of longwall paste backfilling mining.

Abstract: This study compares the accuracy of empirical and regression models for predicting the size distribution of blasted material at drawpoints in sublevel caving. Field data were sourced from Ernest Henry mine (EHM). At EHM, full-scale blasting trials were conducted under controlled conditions by varying explosive density and burden size, with fragmentation measured using laser scanning at different extraction tonnages. To minimise scanning inaccuracies, scan results were combined to represent the particle-size distribution for the EHM data. Five models were evaluated: Kuz-Ram, extended Kuz-Ram, Two Component Model (TCM), Kuznetsov-Cunningham-Ouchterlony (KCO), and a regression-based Underground Ring Blasting Model (URBM) developed in our previous work. Models were assessed for predicting P20, P50, and P80 passing sizes. Results show the extended Kuz-Ram and TCM perform better for finer fragment sizes, with Mean Absolute Percentage Error (MAPE) of 8%. URBM was the most accurate for median and coarse sizes (MAPE 5% for P50 and 3% for P80) and showed the least variability in errors. A SHAP-based sensitivity analysis of the three most accurate models identified key variables for median size prediction, highlighting the importance of rock properties and ring design parameters.