Search Results (532)

In order to solve the problem of ineffective pre-splitting blasting and reduce the damage caused to preserved rock bodies in the Niukutou open-pit quarry in the alpine region of Qinghai Province, China, this study investigated the influence of different delay times on the damage caused to the rock mass, combining numerical calculations with field tests. Using the finite element software ANSYS/LS-DYNA 19.0 and based on the constitutive model of saturated skarn, numerical models of pre-splitting blasting with four different delay times (0 ms, 12 ms, 18 ms, and 24 ms) were established. These models systematically analyze the damage evolution of rock and the effective stress distribution in specific elements under different delay times. The results indicate that a maximum damage depth of 32.56 cm occurs when the inter-hole delay is 0 ms, while a minimum damage depth of 30.61 cm is observed when the inter-hole delay is 18 ms. Further analysis reveals that the peak effective stress is highest when the inter-hole delay is 0 ms, and that the peak effective stress at 18 ms is higher than that at 12 ms and 24 ms. Considering the need to control the damage caused to the surrounding rock and the blasting effectiveness, the best pre-splitting blasting effect is achieved with an inter-hole delay of 18 ms. Field tests show that the damage depth of the retained rock mass is 1.62 m when the inter-hole delay is 0 ms; however, it decreases to 0.90 m when the delay is 18 ms, representing a 44% reduction in rock mass damage depth. This study provides theoretical support and practical guidance for the optimization of pre-splitting blasting in saturated skarn in alpine regions. Full article

This study analyzes the distribution of operating costs along the value chain of an open-pit copper mine with a focus on key operational units or operations such as drilling, blasting, loading, hauling, stockpiling, blending, crushing, milling, and flotation. Using process costing analysis, key cost drivers were identified, and their individual contributions to total expenses were quantified. Results revealed that comminution processes dominate the operational cost structure, with milling accounting for 6.18 USD/ton, representing 59.1% of total operating costs, and crushing costing 1.15 USD/ton, that is, 11% of total operating expenditure. The study also highlighted several opportunities for cost reduction and enhanced mining sustainability through strategies such as energy consumption optimization, the use of alternative energy sources, and optimized blast design. Finally, valuable insights aimed at promoting sustainable resource utilization, improved cost efficiency, and data-driven decision-making in mining operations are offered to mine planners and operators. This is eventually expected to lay the foundation for benchmarking work on the establishment of a baseline and standards for similar mining operations. Full article

The safety production of gold, silver, copper, and other important metals is seriously threatened in the process of mining from open-pit to underground due to various factors such as infiltration caused by rainfall and unloading during mining. Furthermore, the current situation of open-pit mining in an increasing number of mines presents a high and steep terrain, which poses significant security risks. Accordingly, it is of great practical significance to investigate the failure mechanism of high-slope angles to ensure the long-term safe mining of mines, considering factors such as rainfall infiltration and excavation unloading. In this study, the slope failure of high-slope angles (45°, 55°, and 65°) under rainfall-mining coupling was analyzed using the discrete element MatDEM numerical simulation software. Herein, the stress distribution, failure characteristics, and energy conversion of the model were simulated under different slope angles to analyze the failure mechanism at each stage. The simulation results show that the damage scale is smallest at 55° and largest at 65°. This indicates that setting the slope angle to 55° can reduce the risk of slope instability. Moreover, the reduction of elastic potential energy during the mine room mining stage is similar to that of mechanical energy. During the pillar mining stage, stress is concentrated in each goaf, resulting in a greater reduction in mechanical energy compared to elastic potential energy. Finally, after the completion of the continuous pillar mining stage, stress becomes concentrated in the failure area, and the effect of the slope angle on mechanical energy reduction becomes evident after the complete collapse of the model. Full article

Soil degradation caused by mining activities has seriously affected the ecological environment of mining areas. Improving the soil quality is the key to solving this problem. This study examined the impact of adding Effective Microorganism (EM) agents and maize straw to the soil from the dump of the Ordos Rongheng open-pit coal mine. We conducted a two-factor complete experiment, varying the amounts of EM agents (0 g·kg⁻¹, 0.1 g·kg⁻¹, 0.2 g·kg⁻¹, 0.3 g·kg⁻¹, and 0.4 g·kg⁻¹) and maize straw (0 g·kg⁻¹, 5 g·kg⁻¹, 10 g·kg⁻¹, 15 g·kg⁻¹, and 20 g·kg⁻¹). Changes in the soil’s physical, chemical, and biological properties were assessed using a six-month-long potting experiment, and a minimum data set was established for soil quality evaluation. Our results indicated that both EM agents and maize straw improved the soil quality. Both additions reduced the soil’s bulk density and pH while increasing its porosity, organic matter, total available nutrients, enzyme activity, and microbial diversity. However, maize straw had no significant effect on the soil moisture content and total available phosphorus, and EM agents did not significantly impact organic matter. The interaction between the two treatments was not significant for soil moisture content, capillary porosity, and total potassium. Finally, we identified five key indicators affecting soil’s quality: the bulk density, available potassium, alkaline phosphatase, bacterial Chao1 index, and fungal Shannon index. The soil quality index (SQI) ranged from 0.158 to 0.568, with the highest SQI being observed with 0.1 g·kg⁻¹ EM agents and 20 g·kg⁻¹ maize straw, which was significantly higher than those from other treatments. New insights into the improvement of soil quality in open-pit mines are provided by these results, which may help guide future ecological restoration of mines. Full article

Mining may cause devastating environmental impacts through large-scale land transformations. However, mining-induced land transformations are poorly understood relative to a mine’s productivity or life cycle. We integrated satellite imagery, geographic information systems (GISs), and mine site production data (ore, concentration, and waste) to conduct a detailed spatiotemporal analysis of 15 open-pit copper mines in Chile, distinguishing six types of features. Although the occupied area (9.90 to 149.61 km² in 2020) and composition vary across mines, facilities for waste storage occupy the largest proportion (>50%) of the transformed land area, emphasizing the need for proper waste management. The analysis of land transformation factors (the transformed land area per unit production) showed high variation (0.006178 to 0.372798 m²/kg-Cu) between mines over time. This reveals a significant problem in the historical practice of using averages from life cycle assessment (LCA) databases. This research reveals the significance of geospatial analyses in assessing mining-induced land transformation, and it provides geospatial data for land-related LCA. Mining companies are encouraged to disclose GIS information regarding land transformation to foster transparency and social responsibility, as well as to promote responsible and sustainable mining. Full article

This study examines the socio-technical challenges and public acceptance of hybrid pumped-hydropower storage (HPHS) technology within the broader context of energy transition in two European coal-mining regions: Western Macedonia, Greece, and the Łódzkie Region, Poland. These regions, deeply rooted in lignite mining, face profound socio-economic transformations driven by the EU Green Deal and its commitment to achieving net-zero emissions by 2050. The transition from coal dependency to renewable energy represents not only a critical environmental goal but also a significant socio-economic challenge for local communities, necessitating innovative and inclusive strategies to mitigate impacts and ensure equitable outcomes. The research integrates desk studies with stakeholder surveys (n = 129) to assess public awareness, perceived impacts, and acceptance of HPHS technology as a repurposing solution for decommissioned open-pit lignite mines. Results reveal that while awareness of the energy transition process is high (90% in Western Macedonia and 80% in Łódzkie Region), familiarity with HPHS technology varies significantly (76% and 48%, respectively). Support for implementing HPHS in former mining sites is stronger in Western Macedonia (73%) compared to Łódzkie Region (63%), with knowledge of HPHS correlating positively with acceptance (r = 0.83, p < 0.01). Both regions recognize the environmental benefits of HPHS, including improved air quality and biodiversity; yet, socio-economic challenges such as job losses, reduced income levels, and limited opportunities for reskilling persist, particularly in Łódzkie Region, where 77% of respondents view the energy transition as negatively impacting the labor market. By focusing on regions historically dependent on mining, this study highlights the critical role of addressing the unique needs of communities undergoing systemic transformation. The repurposing of former lignite mines into HPHS facilities offers a promising pathway for balancing environmental objectives with local socio-economic revitalization. However, success requires region-specific strategies, including transparent communication, stakeholder involvement, and targeted investment in workforce adaptation and infrastructure. These findings contribute to the growing discourse on how socially inclusive and technically feasible solutions can drive equitable energy transitions in post-mining regions. Full article

The size distribution of rock fragments significantly influences subsequent operations in geotechnical and mining engineering projects. Thus, accurate prediction of this distribution according to the relevant blasting design parameters is essential. This study employs artificial intelligence methods to predict the fragmentation of open-pit bench blasting. The study employed a dataset comprising 97 blast fragment samples. Random forest and XGBoost models were utilized as base learners. A prediction model was developed using the stacking integrated strategy to enhance predictive performance. The model’s performance was evaluated using the coefficient of determination (R²), the mean square error (MSE), the root mean square error (RMSE), and the mean absolute error (MAE). The results indicated that the model achieved the highest prediction accuracy, with an R² of 0.943. In the training set, the model achieved MSE, RMSE, and MAE values of 0.00269, 0.05187, and 0.03320, while in the testing set, these values were 0.00197, 0.04435, and 0.03687, respectively. The model was validated using five sets of actual blasting block data from a northeastern mining area, which yielded more accurate prediction results. These findings demonstrate that the stacking strategy effectively enhances the prediction performance of a single model and offers innovative approaches to predicting blasting block size. Full article

To investigate the dynamic wave propagation characteristics and dynamic response of heterogeneous layered slopes under a blasting vibration, a modeling method considering the slope’s layered dip angle and heterogeneity was proposed. Different dip jointed slope models were established using the Weibull random distribution function introduced to realize the stochastic distribution of rock mechanics parameters, representing heterogeneity. Taking the background project of the Sijiaying Yanshan Open-Pit Iron Mine as an example, through numerical simulation, the effects of different joint dip angles and rock hardness on the slope’s dynamic response were analyzed in detail. The sensitivity of the elastic modulus, cohesion, and friction angle to the slope dynamic response was also investigated. A comparative analysis of the amplification effects between a jointed slope and heterogeneous slope was conducted. Finally, the dynamic stability of the jointed slope and heterogeneous slope under a blasting load was analyzed. The results indicate that the Peak Ground Acceleration (PGA) of jointed slopes with dip angles of 45° and 60° is generally higher than that of slopes with a 0° dip angle and without joints. The smaller the rock mass heterogeneity, the smaller the PGA at the measuring points, and the less sensitive the PGA is to variations in the three quantities. Under the same physical and mechanical parameters of the rock, the amplification factor of jointed slopes is generally greater than that of heterogeneous slopes. Under the blasting load, the overall dynamic time-series safety factors of both slopes decrease first and then increase, with the safety factor reaching its lowest value at the location of the strongest blasting vibration wave. This study can provide guidance for the blasting design and safety protection of layered dip slopes and serve as a reference for the analysis of blasting impact laws in similar mines. Full article

Mining and mineral processing are essential for the functioning of many economic sectors and for meeting human needs. Diagnostics and evaluations of faults are necessary to ensure the successful and responsible management of mining and processing processes for mineral raw materials. Fault-free operation contributes to increased efficiency, productivity, safety, and reliability, reduces the cost of the process under consideration, and reduces environmental impacts. This study aims to identify and analyze possible component failures associated with the jaw crusher used in the process of andesite crushing in an open-pit quarry and compare different approaches to their assessment. The benefit of this is using three different failure analysis methods to assess the criticality of individual jaw crusher components. This approach’s novelty lies in the synergy that occurs when assessing the failures’ impacts on safety, quality, and the environment. Full article

Under regional environmental conditions such as open-pit mines and construction sites, there are usually fixed GNSS measurement points. Around these fixed stations, there are also mobile GNSS measurement modules. These mobile measurement modules offer advantages such as low power consumption, low cost, and large data volume. However, due to their low accuracy, these modules can only provide approximate positions as monitoring data, such as for vehicle management in open-pit mines. To extract more information from the existing large volume of low-accuracy data, it is necessary to process these low-accuracy data. Under conditions of the same time and space in a small area, factors affecting measurement accuracy can be comprehensively considered. By analyzing the temporal GNSS data within the same spatiotemporal small region and understanding the variation patterns of measurement errors, a general equation for measurement error variation can be formulated. Using filtering methods, the data quality can be improved. Through the analysis of the experimental data in this study, it was found that the variation patterns of measurement data obtained by devices of the same accuracy during the same time period are generally consistent. After applying filtering methods, the measurement accuracy of each station improved by up to approximately 95.9%, with a minimum improvement of approximately 84.4%. Under the condition of a 95% confidence level, the reliability increased by up to approximately 73.2%, with a minimum improvement of approximately 58.2%. These experimental results fully demonstrate that under regional spatiotemporal conditions, the temporal data obtained by GNSS measurement devices with similar accuracy exhibit similar error distribution patterns. Applying the same filtering method can significantly improve the accuracy and reliability of measurement data. Full article

The increasing demand for gold necessitates the development of sustainable and environmentally friendly recovery methods, particularly from mining waste. In this study, trace and ultra-trace levels of gold ions were preconcentrated using solidified floating organic drop microextraction (SFODME) and quantified by flow injection–flame atomic absorption spectrometry (FI-FAAS). Sodium diethyldithiocarbamate was used as the chelating agent. Key parameters, including the pH, buffer volume, complexing agent concentration, salt effect, extraction time, stirring speed, temperature, and final volume, were optimized using univariate analysis, yielding an enhancement factor of 42.6. The method demonstrated linearity between 20 and 450 µg/L, with limits of detection and a quantification of 5.03 µg/L and 16.76 µg/L, respectively. In order to evaluate the applicability and reliability of the developed method, the method was applied to certified reference samples (Rocklabs CRM SE114, OREAS CRM 61 f, OREAS CRM 231, and OREAS CRM 235) and real mining samples (mining waste samples from an open pit gold–silver mine in the Aegean Region and tailing samples from an underground gold–silver mine in the Aegean Region) after the real sample preparation procedure. The method was further evaluated for the environmental impact using the Analytic GREEnness (AGREE) metric, based on the 12 principles of green chemistry. Full article

Mining projects are intricate, requiring significant time and investment for feasibility studies, despite a low likelihood of reaching execution. Accurate project factors can optimize costs across the study, execution, and operation phases. This work proposes a strategic approach to define the production rate in conceptual projects of critical raw materials, based on well-established formulae from Taylor, Long, and Singer, focusing on copper, zinc, and lead. Copper and zinc are crucial for renewable energy systems and low-carbon technologies, while lead supports energy storage applications. A dataset containing mine production and mineral resources from several mine projects, gathered from a specialized global company, was used to create a production rate equation and then compared using an adherence indicator to validate the formulae. The best adherence indicator from earlier studies was 59%. Copper projects did not show good adherence to the new formulae. Zinc and lead projects showed very good results, generating three formulae with good adherence numbers (above 70%), and they can be taken as a reference to calculate the production rate of new open-pit and underground mining projects. These findings offer a reliable strategic approach for estimating production rates in early-stage zinc and lead projects, enhancing the efficiency of the conceptual study phase in mining. Full article

Drilling and blasting is the conventional method used for rock fragmentation in open pit mining. Blast-induced damage can reduce the level of stability of benches and pit slopes. To develop an optimal blast design, an adequate knowledge of the rock properties and in situ fractures is needed. Fractures are generally the paths of least resistance for explosive energy and can affect the intensity of blast-induced damage. Discrete Fracture Networks (DFNs) are 3D representations of joint systems used for estimating the distribution of in situ fractures in a rock mass. The combined finite/discrete element method (FDEM) can be used to simulate the complex rock breakage process during a blast. The objective of this paper is to develop a methodology for assessing the influence of in situ joints on post-blast fracturing and the associated wall damage in 2D bench blast scenarios. First, a simple one-blasthole scenario is analyzed with the FDEM software Irazu 2D and calibrated based on a laboratory-scale blasting experiment available from previous literature. Secondly, more complex scenarios consisting of one-blasthole models at the bench scale were simulated. A bench blast without DFN (base case) and one with DFN were numerically simulated. The model with DFN demonstrated that the growth path and intensity of blast-induced fractures were governed by pre-existing fractures, which led to a smaller wall damage area. The damage intensity for the base case scenario is about 82% higher than for the blast model with DFN included, which highlights the significance of in situ fractures in the resulting blast damage intensity. The methodology for developing the DFN-included blasting simulation provides a more realistic modeling process for blast-induced wall damage assessment. This results in a better characterization of the blast damage zone and can lead to improved slope stability analyses. Full article

In order to study the stability of rock layers and the change in volumetric water content at different stages of mining under an environment of heavy rainfall, a self-developed large-scale open-pit-to-underground-mining similar physical model was used, and the intensity of continuous rainfall was set at 40 mm/h. The results of this study show that fissures accelerated the instability of rock strata, and when spreading to different rock strata, they were prone to form subsidence cracks and produce collapse zones. The volumetric water content is closely related to the stability of the rock formation. An ‘arch-shaped collapse zone’ was formed in an interval of (0.9~1.8 m), and a convex spreading zone of volumetric water content was formed in an interval of (1.2~1.6 m). The infiltration line shows different diffusion patterns in different mining stages. In the early stage of mining, the volumetric water content infiltration line is roughly parallel to the slope; in the middle stage of mining, the infiltration line diffuses parallel to the two ends of the interface with the slope and diffuses convexly in the middle; in the late stage of mining, the infiltration line shows a pattern of rapid diffusion in the lower area, rapid diffusion in the middle area, and slow diffusion in the middle area. Therefore, in the process of the mining stage, it is necessary to focus on mining area fissure changes and monitor the point water content for sudden changes and other indicators. This study has certain guiding significance for safe production. Full article

Following open-pit coal mining in the Powder River Basin, landscape reconstruction includes the construction of backfill aquifers from overburden waste rock. With overburden disaggregation and the re-introduction of groundwater, the weathering of newly available mineral surfaces and mobilization of nanomaterials can impact groundwater quality even when such issues were not previously detected in the overburden’s groundwater. Kinetic columns of Powder River Basin waste rock were used to evaluate backfill construction options—zeolite amendment, and soil amendment, compaction, rinse—that could reduce potential groundwater quality impacts. The leachate from each column was collected twice weekly for 20 weeks. The Eh and pH of the leachate substantially varied during an initial high-weathering period indicative of the traditional weathering of newly exposed mineral surfaces and the weathering and flushing of mobile particles. Correspondingly, select elements, such as arsenic and cadmium, were present in relatively high concentrations during this initial weathering period. Waste rock that was compacted or rinsed produced leachate with less solutes and potential contaminants when compared to the unaltered and zeolite- and soil-amended waste rock. Greater compaction during backfilling is possible but may require additional consideration for connecting the surface drainage network to the surrounding area. Rinsing of the waste rock is a viable construction option because of the temporary storage of the waste rock prior to backfilling but would require leachate collection for contaminant treatment. Full article