Search Results (80)

This study investigates the stability risks associated with a substandard-thickness (42 m) backfill isolation layer in the open-underground coordinated mining system of the Yongping Copper Mine’s eastern panel at the −150 m level. A numerical simulation based on FLAC3D 3.00 was conducted to evaluate the impacts of four mining sequences (south-to-north, north-to-south, center-to-flank, and flank-to-center) on stress redistribution and displacement evolution. A three-dimensional geomechanical model incorporating lithological parameters was established, with 23 monitoring points tracking stress and displacement dynamics. Results indicate that the mining sequence significantly influences the stability of both the isolation layer and the slope. No abrupt displacement occurred during mining, with incremental isolation layer settlement controlled within 3 mm. Post-mining maximum displacement increased to 10–12 mm. The “north-to-south” sequence emerged as the theoretically optimal solution, reducing cumulative displacements in pillars and stopes by 9.1% and 7.8%, respectively, compared to the suboptimal scheme. However, considering the engineering continuity of the existing “south-to-north” sequence at the −100 m level, maintaining consistent directional mining at the −150 m level is recommended to ensure synergistic disturbance control, ventilation system stability, and operational management coherence. Full article

Here, we report the characterization of two Cupriavidus strains, NOV2-1 and OV2-1, isolated from an iron-oxide deposit in an underground tunnel of the Naica mine in Mexico. This unique biotope, characterized by its high temperature (≈50 °C) and the presence of heavy metals, is no longer available for sampling at this time. The genomes of NOV2-1 and OV2-1 comprised two replicons: a chromosome of 3.58 and 3.53 Mb, respectively, and a chromid of 2.1 Mb in both strains. No plasmids were found. The average nucleotide identity and the core genome phylogeny showed that NOV2-1 and OV2-1 belonged to the Cupriavidus gilardii species. NOV2-1 and OV2-1 grew up to 48 °C, with an optimal temperature of 42 °C. Discrete differences were observed between C. gilardii CCUG38401^T, NOV2-1, and OV2-1 in the biochemical tests. NOV2-1 and OV2-1 presented resistance to zinc, lead, copper, cadmium, nickel, and cobalt. Several complete and incomplete gene clusters related to the resistance to these heavy metals (ars, czc, cop 1, sil-cop 2, cup, mmf, and mer) were detected in the genome of these strains. Although further studies are needed to determine the origin and role of the detected gene clusters, it is suggested that the czc system may have been mobilized by horizontal gene transfer. This study expands the extreme biotopes where Cupriavidus strains can be retrieved. Full article

Determining the presence and abundance of uranium mineralization at legacy mine sites is important both for responsible environmental management and potential resource recovery. Technologies that can make such determinations quickly and at low costs are highly desirable. The current work focuses on demonstrating the use of simple handheld commercial-off-the-shelf (COTS) devices for rapidly determining the presence and distribution of uranyl minerals within an abandoned copper–uranium mine. Specifically, this work demonstrates the use of a COTS iPhone 13 Pro smartphone with an inbuilt solid-state LiDAR (laser) scanner in combination with a handheld LED-based UV torch to conduct a rapid fluorescence imaging photogrammetry survey aimed at rapidly determining the distribution of uranyl minerals within an abandoned copper–uranium mine in the Sierra Ancha Wilderness Area, Gila County, Arizona, USA. Such a simple methodology, presented herein, can be used to quickly determine the distribution of uranyl minerals on exposed surfaces within the underground workings and provide an indication of the presence of primary uranium ore minerals buried within the surrounding rock. 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

This article presents the results obtained from a high-resolution wide-azimuthal 3D seismic reflection method used for the prediction and detailed exploration of complex ore targets in the Zhezkazgan ore district of Central Kazakhstan. We demonstrate the ability of modern seismic data processing and interpretation systems to identify underground mine objects associated with stratiform copper sandstones and improve geological models. The 3D seismic imaging tools, along with the implementation of a modern seismic processing sequence, allow for the clarification of geological structures in the studied area. The target stratigraphic horizons, large faults, and microtectonic disturbances (small faults and cracks) are clearly delineated in the seismic volumes. The use of seismic attribute analyses on geological data is tested to identify ore horizons and deposits with volumetric predictions of copper mineralization. Recommendations for further exploration drilling were developed, and five new wells were drilled. Copper mineralization was confirmed in all recommended wells. We carried out a marketing review in Kazakhstan and uncovered an increased interest among subsoil use companies in 3D seismic exploration technology to investigate existing mining objects of different genetic types. These results demonstrate the expediency of 3D seismic exploration aimed at identifying ore targets. 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

Potential faults are common sensitive geological bodies that affect the safe mining of underground mines, often leading to major accidents such as rock instability and rockburst during mining. The failure mechanism of faults has been widely studied. However, due to the spatiotemporal specificity of fault occurrence, there are few theoretical and mathematical methods suitable for effective analysis in mine safety risk management. This study aims to introduce fractal theory to characterize the spatiotemporal activity fractal characteristics of induced faults intersecting the mining site and roadway during the mining process of the Ashele copper mine in China. Using microseismic systems and fractal theory, a spatiotemporal fractal model of the fault slip process is constructed, and a fractal analysis method is proposed. The fractal dimension value is calculated based on the spatiotemporal parameters of different segments and stages. The fractal dimension is used to characterize and analyze the evolution of the fault. The physical formation process of potential faults and the relationship between fractal dimension values and multiple parameters, including spatial clustering, regional distribution characteristics, and energy-release characteristics, were analyzed based on the division of events into different time stages. Discovering fractal dimension’s temporal and spatial–temporal characteristics can provide technical references for mine disaster prevention. Full article

The thermal regime of underground mines, shaped by air temperature, velocity, and relative humidity, is a crucial factor for production and the health and safety of miners. While many aspects of this thermal regime have been thoroughly studied in the literature, local heat sources from mechanized equipment, such as load–haul–dump machines, conveyors, and auxiliary fans, have received comparatively little attention despite their significant impact on the thermal environment in mining development areas and stopes. This paper presents findings from a comprehensive study of the microclimatic air parameters in several nickel–copper and potash mines. We focus specifically on variations in air temperature in areas where mining equipment is operational. The heat output from different types of equipment, including load–haul–dump units, cutter–loaders, drilling rigs, conveyors, and auxiliary fans, has been quantified. We established empirical relationships for heat emissions from these machines and conducted a comparative analysis of their heat outputs. The main advantage of these relationships is their simplicity and the minimal number of input parameters required, making them practical for use in the field. Full article

The detection and monitoring of mining-induced seismicity are essential for understanding the mechanisms behind earthquakes and mitigating seismic hazards. However, traditional underground seismic monitoring networks for mining-induced seismicity are challenging to install and operate, which has limited their widespread application. In recent years, an alternative approach has emerged: utilizing dense seismic arrays at the surface to monitor mining-induced seismicity. This paper proposes a rapid and efficient data processing scheme for the detection and monitoring of mining-induced seismicity based on the surface dense array. The proposed workflow includes machine learning-based phase picking and P-wave first-motion-polarity picking, followed by rapid phase association, precise earthquake location, and template matching for detecting small earthquakes to enhance the completeness of the earthquake catalog. Additionally, it also provides focal mechanism solutions for larger mining-induced events. We applied this workflow to the continuous waveform data from 90 seismic stations over a period of 27 days around the Dongchuan Copper Mine, Yunnan Province, China. Our results yielded 1536 high-quality earthquake locations and two focal mechanism solutions for larger events. By analyzing the spatiotemporal distribution of these events, we are able to investigate the mechanisms of the induced seismic clusters near the Shijiangjun and Lanniping deposits. Our findings highlight the excellent monitoring capability and application potential of the workflow based on machine learning and template matching compared with conventional techniques. Full article

The goal of this study was to develop a model describing the relationship between the ground-displacement-caused tremors induced by underground mining, and mining and geological factors using the Random Forest Regression machine learning method. The Rudna mine (Poland) was selected as the research area, which is one of the largest deep copper ore mines in the world. The SAR Interferometry methods, Differential Interferometric Synthetic Aperture Radar (DInSAR) and Small Baseline Subset (SBAS), were used in the first case to detect line-of-sight (LOS) displacements, and in the second case to detect cumulative LOS displacements caused by mining tremors. The best-prediction LOS displacement model was characterized by R² = 0.93 and RMSE = 5 mm, which proved the high effectiveness and a high degree of explanation of the variation of the dependent variable. The identified statistically significant driving variables included duration of exploitation, the area of the exploitation field, energy, goaf area, and the average depth of field exploitation. The results of the research indicate the great potential of the proposed solutions due to the availability of data (found in the resources of each mine), and the effectiveness of the methods used. Full article

Cement production may involve excessive use of natural resources and have negative environmental impacts, as energy consumption and CO² emissions can cause air pollution and climate change. Cement kiln dust (CKD), a by-product waste material, is also a primary issue associated with cement production. Utilizing CKD in mining applications is a pathway to eco-sustainable solutions. Cemented paste backfill (CPB) made with mine tailings is an efficient method for void backfilling in underground mines. Therefore, this study investigated the eco-sustainable utilization of CKD as a co-binder material that can partially replace cement in CPB prepared with copper tailings. At 7, 14, 28, 56, and 90-day curing times, the experimental campaign measured the physical and mechanical parameters of the cured CPB samples, including density, UCS, and elastic modulus (stiffness). Additionally, the CPB-cured mixes were analyzed using XRF, X-ray XRD, SEM, and EDX techniques to link the mineral phases and microstructure to mechanical performance. Four proportions (5, 10, 15, and 20%) of CKD represented in 75 samples were prepared to replace ordinary Portland cement (OPC) in the CPB mixtures, in addition to the reference mix (control) with 0% CKD. As all combinations exceed the compressive strength of CPB required for achieving stability in underground mines, the results showed that CKD could be utilized advantageously as a partial substitute for OPC with a proportion of up to 20% in the CPB mixture. When tested after 90 days, the combination modified with 5% CKD exhibited comparatively higher compressive strength than the control mixture. Full article

The article presents the results of significance analyses of selected mining and geological variables for an area of underground mining activity. The study area was a region of an underground copper ore mine located in southwest Poland. The input data consisted of satellite radar data from the Sentinel 1 mission as well as mining and geological data. The line-of-sight subsidence, calculated with the use of the small baseline subset method and arranged in time series, was decomposed to extract the vertical component. The significance analysis of individual variables for the observed surface subsidence was performed using the SHapley Additive exPlanations method for the XGBoost machine learning model. The results of the analysis showed that the observed ground surface subsidence velocities were most influenced by the thickness of the PZ3 layer, which is located approximately 200 m above the roof of the mined seam, the thickness of the seam, and the timing of mining. It was also found that the proposed model was able to detect a nonlinear relationship between the analyzed excavations. The most significant influence on ground subsidence over mine excavations are mining parameters such as the spatially averaged thickness of the deposit and the time since liquidation of the deposit. The proposed approach can be successfully employed in planning both mining operations and mine closure in such a manner that the environmental impact is minimized. Full article

Rockbursts represent one of the most serious and severe natural hazards emerging in underground copper mines within the Legnica–Glogow Copper District (LGCD) in Poland. The contributing factor determining the scale of this event is mining-induced seismicity of the rock strata. Extensive expertise of the copper mining practitioners clearly indicates that high-energy tremors are the consequence of tectonic disturbances or can be attributed to stress/strain behaviour within the burst-prone roof strata. Apparently, seismic activity is a triggering factor; hence, attempts are made by mine operators to mitigate and control that risk. Underlying the effective rockburst control strategy is a reliable seismicity forecast, taking into account the causes of the registered phenomena. The paper summarises the geomechanics analyses aimed to verify the actual seismic and rockburst hazard levels in one of the panels within the copper mine Rudna (LGCD). Two traverses were designated at the face range and comparative analyses were conducted to establish correlations between the locations of epicentres of registered tremors and anomaly zones obtained via analytical modelling of changes in stress/strain behaviours within the rock strata. The main objective of this study was to evaluate the likelihood of activating carbonate/anhydrite layers within the main roof over the excavation being mined, with an aim to verify the potential causes and conditions which might have triggered the registered high-energy events. Special attention is given to two seismic events giving rise to rockbursts in mine workings. Results seem to confirm the adequacy and effectiveness of solutions provided by mechanics of deformable bodies in the context of forecasting the scale and risk of dynamic phenomena and selecting the appropriate mitigation and control measures in copper mines employing the room-and-pillar mining system. Full article

The importance of the mining/milling industry in increasing the growth level and welfare of countries is quite high. However, at the end of mining/milling processes, huge amounts of waste (often known as tails) are inevitably produced that have no economic value and can even be considered dangerous due to some heavy metals they contain. These tails are highly problematic due to both their volume (difficult to manage environmentally) and toxicity (potential to cause acid/leach waters) and need to be handled outside of existing disposal methods. This article presents the effective and sustainable handling and application of tails resulting from the enrichment of copper–zinc ores, which are actively engaged in metallic mining activities in the northeast of Türkiye, with the submarine tails disposal (STD) method. In the mining operation under study, some (~55–60 wt.%) of the tails are employed as underground fill, even though the residual part is disposed of by the STD method. The characterization of ore beneficiation tails, their transportation to the subsea via a pipeline system, and discharge monitoring results are detailed in the present investigation. According to the limitations which are indicated by the Turkish Control of Water Contamination regulation, the concentration of Pb-Cu found in the results was under the allowable limit of 0.05 mg/L. The allowed 2 mg/L limit for Zn was not surpassed mainly by the concentration found in the collected samples. pH values were almost above the allowable limit of pH > 5. The results reveal that the STD technique works quite well as an integrated mine tails method in the mine under study. Full article

This study examines the optimization of ore receiving bins in underground copper mines, targeting the reduction of rapid wear and tear on bin components. The investigation identifies the primary wear contributors as the force exerted by the accumulated ore and the velocity at which ore particles move. By altering design and operational parameters, the objective is to decrease wear at key points such as transfer areas, thereby improving the efficiency and service life of retention bunkers. A Discrete Element Method (DEM) model of the bin was created and validated against actual mining conditions to study the impact of material flow on wear. The optimization approach used a constrained gradient descent algorithm to minimize factors like particle velocity and pressure force, while maintaining the efficiency of the bin. The findings provide valuable insights for the future design enhancements, potentially improving the operational performance of retention bunkers in the mining industry. Full article