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As the shallow coal seams are gradually being exhausted, mining of the lower group of coal seams in the shallowly buried proximity coal seam group becomes inevitable. Due to geological conditions affecting the upper group coal seams, various coal mining methods have resulted in a significant number of non-sufficient and sufficient collapse mining areas. The presence of water and gas in these mining areas can potentially impact the safe production of the lower group coal seams through inter-layer rock fractures. Therefore, studying the evolution characteristics and formation mechanism of inter-layer rock fractures is of utmost importance. In this paper, we employ theoretical analysis, numerical simulation, and similar simulation methods to investigate the evolution characteristics and formation mechanism of inter-layer rock fractures during the mining of the lower 3–1 coal seam. We specifically focus on the formation of different mining areas in the upper 2–2 coal seam, using the mining of 2–2 and 3–1 coal seams in the Hanjiawan coal mine as our research context. The study results reveal that the inter-layer rock fractures exhibit an overall positive trapezoidal distribution in different mining areas. We quantify the variation in density and width of inter-layer rock fractures in the two mining areas by utilizing the concept of rock damage degree. We analyze the overall damage degree, tensile damage degree, and shear damage degree ratios. The formation of inter-layer rock fractures is primarily influenced by the combined effect of various coal mining methods in both the upper and lower coal seams. The stress changes resulting from mining activities in these seams contribute to the development of transverse separation fractures and longitudinal breaking fractures within the inter-layer rock. The stress changes induced by mining operations in the upper and lower coal seams have been analyzed, and distinct stress regions have been identified. To understand the mechanism of inter-layered rock fracture development in the upper and lower coal seams, a mechanical expansion model of inter-layer rock fractures has been constructed for different stress regions. Highlights: The evolution process and development characteristics of inter-layered rock fractures, as well as their differences when different coal mining methods are employed in the upper coal seam, have been revealed. To determine the influencing factors and development patterns of inter-layered rock fractures under different coal mining methods. Quantitatively comparing and analyzing the damage of inter-layered rock and the percentage of damage degree under different coal mining methods, we found that the damage degree was 61% and 52%, respectively. The study shows that when mining the upper coal seam, the inter-layer rock primarily extends through primary microscopic fractures. On the other hand, when opening the lower coal seam, the main development is observed in macroscopic tension fractures and shear misalignment fractures. Based on the study of the development process of macroscopic fractures and microscopic fractures in the inter-layered rock, the mechanism of fracture development and evolution of the inter-layered rock under different coal mining methods has been determined. [ABSTRACT FROM AUTHOR]

The occurrence of potentially toxic elements (PTEs), including twelve heavy metal(loid)s (Cd, Cr, Cu, Ni, Pb, Zn, Hg, As, Co, V, Fe, Mn), fluoride (F−), and nitrate (NO3−) was evaluated in groundwater in the copper mining and smelter area of Bor city (south Carpathian, eastern Serbia). Groundwater samples were analyzed to determine the extent of pollution, identify natural and anthropogenic input of PTEs, and estimate potential human health risks due to exposure to these substances. The results revealed that the groundwater in the study area was highly contaminated with PTEs, particularly Cu and Zn. Multivariate analysis supported the natural and anthropogenic origin of PTEs, with Fe, Mn, and F− classified as naturally occurring, NO3− resulting from agricultural activities, while other PTEs were linked to smelter/mining processes. Geospatial mapping discovered several hotspots with potential high non-cancer and cancer risks to humans through ingestion pathway. From the studied PTEs, As is the most health risk contributing toxic element. The source-specific probabilistic risk assessment indicated the most significant contribution to the hazard index and total cancer risk from accidental leakage of metallurgical wastewater and wastewater from open mine pits. Monte Carlo analysis identified the human body weight and the ingestion rate as the most sensitive risk parameters. The study underscores the need for stringent environmental management measures, emphasizing the critical role of source-specific risk assessments in mitigating potential hazards associated with metallurgical wastewater and open mine pits. [ABSTRACT FROM AUTHOR]

A considerable number of coal mines employed room and pillar mining in the last century in northern China, where the goaf remained stable for a period of time; however, with the increased exposure of coal pillars, their collapse may gradually increase. The stability assessment of these old rooms and pillar goafs is challenging due to their concealment, irregular mining patterns, and the long passage of time. The methodology developed in this study, based on "space-sky-earth" remote sensing such as InSAR to trace historical deformation, the UAV observation of current surface damage, and comparison of mining spaces, can rapidly detect on a large scale the collapse of old goafs and the trend of damage. This study is conducted with an example of a coal mine in Yulin, Northern China, where obtained quantitative surface deformation values were integrated with qualitative surface damage interpretation results, followed by a yearly analysis of the overlying rock movement in accordance with the underground coal mining process. The results show that from 2007 to 2021, corresponding surface deformation and damage occurred following mining progress. However, the room and pillar goaf areas had not undergone any surface deformation, nor had there been incidents of landslides or ground fissures; therefore, it was speculated that no roof collapse had occurred in this region. The surface deformation and damage associated with underground coal mining are complex and influenced by the coal seam occurrence, mining methods, strata lithology, terrain slope, temporal evolution, and anthropogenic modifications. These phenomena are representative of the coal mining area, and this methodology can provide a reference for similar endeavors. [ABSTRACT FROM AUTHOR]

The work presents a history of the exploitation and processing of alluvial gold in Antiquity by the first civilizations of mankind. But those who developed and perfected this technology were the Romans, in Hispania and Britannia, where they mined gold both outcrops and underground. The technology they used was so advanced that it remained unchanged for more than a millennium. [ABSTRACT FROM AUTHOR]

The growing demand for primary mineral resources and the finite nature of mineral reserves necessitate their efficient utilization while minimizing losses. To extend mine life and increase economic reserves, transitioning from open-pit to underground mining has proven to be a viable strategy. Identifying this critical transition depth is pivotal, as it significantly impacts mining profitability. Therefore, in this paper we propose a method to determine the open-pit/underground transition depth based on an economic block model, accounting for the final pit limit and considering the inherent uncertainty in mineral prices. To achieve our research aim, a hypothetical grade model was constructed initially, and we used @Risk software to perform Monte Carlo simulation of copper prices based on historical data. By generating 200 different mineral price scenarios, we created 200 economic block models. Subsequently, nine mining sequences were designed, and seven distinct scenarios were established to ascertain the final open-pit limit and the depth of the transition point between mining methods, contingent on fluctuating mineral prices. Based on the outcomes derived from the seven scenarios, the depth at which the mining method transition from open-pit to underground is recommended to be 375 m from the surface, under the aforementioned uncertainties. This recommendation is based on the cumulative net present value of open-pit/underground mining, as illustrated in scenario number 7. Our findings provide valuable insights for mining companies seeking to optimize resource utilization and maximize profitability while navigating uncertain mineral price environments. [ABSTRACT FROM AUTHOR]

Phytomining (PM) is defined as the process of using plants capable of bio-extracting metals from soil in order to explore them economically. This relatively new, innovative method has been gathering significant attention in both the academic and commercial domains. Conventional mining methods are often economically unviable when applied to lean ores, and they can lead to secondary pollution in soil—a situation that applies to all excavated metals. On the other hand, PM is an environmentally friendly and economically viable solution that addresses the growing demands for metal resources, while simultaneously contributing to energy production by harnessing biomass energy. This comprehensive review presents the current PM techniques, challenges, and the hyperaccumulator plant species that may be used for the extraction of the main targeted elements in the process. Typically, the targeted metals are those of economic value, which can later be deposited or sold to various industries. This review also analyzes the factors influencing the economic viability of PM and proposes potential enhancements. Undeniably, PM offers the opportunity for economically sustainable exploration of metal-rich soils, but its full commercial viability remains constrained under current conditions as scientists are actively searching for the identification and utilization of new hyperaccumulator plant species in different locations worldwide, while creating new relationships and business avenues within the mining industry. Overall, this review highlights the current status of PM technology and the plants used, emphasizing the need for further research to enhance its commercial implementation and its potential to assist the mining industry. We conclude that PM, although a relatively new and unexplored concept, may provide economic and environmental benefits to soil end-users and managers who must cultivate on metal-contaminated soils as PM may turn yield shortages (of specific commercial crops) to benefits if high-yield hyperaccumulators are cultivated for industrial valorization of their high metal-content biomass. [ABSTRACT FROM AUTHOR]

Traditional coal mining processes have increasingly raised concerns about roadways and surface damage. An innovative mining method, based on DSRC technology, has been proposed to address these issues. The DSRC technology involves using bilateral energy gathering devices to achieve roof cutting on both sides of the working face. The N00 method builds upon DSRC technology by incorporating additional auxiliary techniques to achieve roadways and surface protection during mining. With this method, mining N working faces can be accomplished with the advancement of 0 roadway and the retention of 0 coal pillar. The protection mechanism of the DSRC method on roadways and surface is analyzed through theoretical calculation, numerical simulation, and field engineering analysis. The N00 method with DSRC modifies the structure of the roadway roof by changing the long cantilever beam to a short cantilever beam. This modification reduces the stress on the roof and improves the stability of the roadway roof. The DSRC cuts off the stress transmission in a part of the roadway roof, reducing stress concentration on the coal side and enhancing its stability. The N00 method with DSRC increases the amount of strata bulking, utilizing bulking gangue to support the overlying strata, reducing the development height of the plastic zone in the gob, protecting the overlying aquifers, and mitigating damage to the surface ecological environment. Field monitoring results show that the N00 method with DSRC reduces the door-like support stress, NPR anchor cable stress, and deformation of the roadway, decreases stress concentration on the coal side, minimizes surface deformation, and reduces water inflow into the working face. Therefore, the purpose of protecting roadways and the surface is achieved. Highlights: Double-sided roof cutting technique has been proposed to protect roadways and the surface strata. Roadways are protected by altering the structure of the roof and cutting off part of the stress transmission. Surface strata are protected by increasing the amount of strata bulking. [ABSTRACT FROM AUTHOR]

The behaviour of a stratified backfilled stope in terms of strength development and stress distribution has not been well established in the field of rock engineering. Yet, the mining industries with massive ore bodies are looking into high production with a high standard of safety which is mainly governed by large excavation with backfill as a support system. It is difficult to fill these large excavations at one time. Therefore, a subsequent backfilling of the stope layer by layering is adopted, which results in a layered backfill structure. The purpose of this study was to explore the strength development, stress distribution and deformation across the stope supported by both layered and non-layered backfill. It has been observed that the backfill support system gain its strength with time, however, the layered backfill support system loses its strength when more layers are introduced, this is due to the shearing effect around the interfaces of the backfill layers. The impact of layering was validated by 3D numerical simulation. It is therefore concluded that non layered backfill support system are more suitable for stoping mining methods rather than layered support system. [ABSTRACT FROM AUTHOR]

The behaviour of a stratified backfilled stope in terms of strength development and stress distribution has not been well established in the field of rock engineering. Yet, the mining industries with massive ore bodies are looking into high production with a high standard of safety which is mainly governed by large excavation with backfill as a support system. It is difficult to fill these large excavations at one time. Therefore, a subsequent backfilling of the stope layer by layering is adopted, which results in a layered backfill structure. The purpose of this study was to explore the strength development, stress distribution and deformation across the stope supported by both layered and non-layered backfill. It has been observed that the backfill support system gain its strength with time, however, the layered backfill support system loses its strength when more layers are introduced, this is due to the shearing effect around the interfaces of the backfill layers. The impact of layering was validated by 3D numerical simulation. It is therefore concluded that non layered backfill support system are more suitable for stoping mining methods rather than layered support system. [ABSTRACT FROM AUTHOR]

Reclamation is regarded as one of the mining processes that can lessen the environmental impact of its production, particularly for large-scale coal mines that emit significant quantities of greenhouse gases. However, the assessment and evaluation of the reclamation process primarily rely on qualitative methods. Utilizing LANSAT8 Operational Land Imager (OLI) remote sensing in conjunction with GIS, this study aimed to develop a quantitative method for validating the efficacy of a reclamation procedure applicable to the emerging trend of carbon reduction. The empirical formula utilized to compute the annual carbon sequestrations of the reclamation area in the Mae Moh mine exhibited the appropriate spatial relative standard deviation (S-RSD) at 98.25%. The findings indicate that the reclamation area reached its highest level of carbon sequestration in 2022, at 331.28 ± 11.89 ktCO2e, surpassing the baseline of 126.53 ktCO2e. Furthermore, the approach demonstrates significant potential in improving the standard method for assessing reclamation through reforestation. [ABSTRACT FROM AUTHOR]

Backfill coal mining technology has drawn widespread attention due to its benefits of "controlling surface deformation and subsidence, reducing mining-induced disturbance in the stope, and recycling solid mine wastes". However, the backfill coal mining technology is still progressing slowly in China. The geological environment of China's mining areas is complex and highly diversified, and backfill coal mining is expected to fulfill different goals in a wide range of engineering scenarios. These facts explain the poor reproducibility of backfill coal mining projects. This study reviews the existing backfill coal mining systems in China. Based on findings from a survey of engineering cases, we summarize five types of new backfill coal mining methods classified by deployment style; namely, borehole grouting backfill, roadway backfill, borehole–roadway backfill, in situ backfill, and roadway-in-situ backfill. A total of 15 backfill coal mining methods falling into the above five categories are described. An engineering design workflow for backfill coal mining consisting of five steps is proposed; namely, identifying the targets of backfill, analyzing the feasibility of deploying the backfill system, comparing the engineering quantities of different engineering schemes, estimating the economic efficiency of backfill, and backfill performance tracking and monitoring. Real cases of backfill engineering design are analyzed to inform the fast and reasonable design of backfill strategy for specific working faces in certain coal mines. [ABSTRACT FROM AUTHOR]

The novel ternary composites BiOBr-TiO2-attapulgite (BTA) were synthesized using a simple hydrothermal and water-bath method, exhibiting excellent photocatalytic performance to multiple xanthates. For the BTA photocatalyst, TiO2 and BiOBr were uniformly loaded onto the surface of acid-activated attapulgite. As a widely used collector in mining processes, sodium ethyl-xanthate (SEX) was selected as the target pollutant due to its high toxicity. The BTA ternary photocatalyst demonstrated significantly higher adsorption and photocatalytic degradation performance compared to TiO2 nanoparticles, BiOBr nanosheets, and BiOBr-TiO2 heterojunction. Structural characterization and experimental results indicated that the exceptional photocatalytic degradation efficiency of BTA was mainly attributed to the formation of a heterojunction between BiOBr and TiO2, as well as the presence of additional active adsorption sites provided by attapulgite. Free radical scavenging experiments and EPR results confirmed that the photogenerated holes were the predominant active species in photodegrading SEX throughout the entire experiment. The LC-MS results provided insight into potential degradation pathways of SEX. This research demonstrates that BTA, as a novel triple composite material, achieves rapid and complete degradation to 20 mg/L SEX within 20 min. This work presents a novel approach to synthesize mineral-based photocatalysts, which have broad prospects for application in flotation wastewater treatment. [ABSTRACT FROM AUTHOR]

• Exploring pedestrian crash patterns at night is a noteworthy ongoing traffic safety concern. • Association Rules Mining methodology is utilized to reveal the association of crash-contributing factors separately at the intersection and segment locations. • This study utilized 5 years (2015–2019) of pedestrian fatal and severe injury crashes in Louisiana that occurred at night. • At the intersection, a few critical contributing factors are – driver/pedestrian alcohol involvement, driver age (15–24, >64), pedestrian age (<15, >64), and rainy weather conditions. • At the segments, a few critical contributing factors are – dark lighting conditions, open country location, high posted speed limit, interstate, and two-way roads with no physical separation. Introduction : Pedestrian safety at nighttime is an ongoing critical traffic safety concern. Although poor visibility is primarily associated with nighttime pedestrian crashes, other contributing factors such as humans, vehicles, roadways, and environmental factors interact with each other to cause a crash. Additionally, the pattern of nighttime pedestrian crashes differs significantly according to the intersection and segment location, which requires further exploration. Data: This study applied Association Rules Mining (ARM), a rule-based machine learning method, to reveal the association of nighttime pedestrian crash risk factors according to the intersection and segment locations using 2,505 nighttime pedestrian fatal and injury crashes in Louisiana (2015–2019). Results and conclusions: Based on the generated rules, the results show that nighttime pedestrian crashes at the intersection are associated with right-turn vehicle movement, older drivers (>64 years) at the high-speed intersection, senior pedestrians (>64 years) in rainy weather conditions, violation by pedestrian age group '<15 years', and alcohol-intoxicated pedestrian violation in business/industrial areas. Additionally, 'careless operation' at the intersection is associated with alcohol-involved drivers. Most of the nighttime pedestrian crashes at segments are associated with roadways with no physical separation and the absence of streetlights. Driver alcohol involvement and their physical condition (inattentive/distracted) are also associated with pedestrian crashes associated at the segment location at night. Other segment pedestrian crashes are linked to the interstate in dark conditions, open country locations, and high-speed roadways. Additionally, the crash site investigation identified several critical pedestrian safety concerns including the lack of crosswalk facilities, high driveway density, and pedestrian behavioral patterns (e.g., crossing at roadway segments close to the intersection location). Practical Applications: The findings of this study can be used for selecting the appropriate countermeasures based on a case-by-case basis. The exposure patterns can be used in educational campaigns to strategically reduce nighttime pedestrian crashes. [ABSTRACT FROM AUTHOR]

Approximately 50% of the world's uranium is mined in a closed way using underground well leaching. In the process of uranium mining at formation-infiltration deposits, an important role is played by the correct identification of the formation of reservoir oxidation zones (ROZs), within which the uranium content is extremely low and which affect the determination of ore reserves and subsequent mining processes. The currently used methodology for identifying ROZs requires the use of highly skilled labor and resource-intensive studies using neutron fission logging; therefore, it is not always performed. At the same time, the available electrical logging measurements data collected in the process of geophysical well surveys and exploration well data can be effectively used to identify ROZs using machine learning models. This study presents a solution to the problem of detecting ROZs in uranium deposits using ensemble machine learning methods. This method provides an index of weighted harmonic measure (f1_weighted) in the range from 0.72 to 0.93 (XGB classifier), and sufficient stability at different ratios of objects in the input dataset. The obtained results demonstrate the potential for practical use of this method for detecting ROZs in formation-infiltration uranium deposits using ensemble machine learning. [ABSTRACT FROM AUTHOR]

The solar salt mining process involves collecting salt water from the sea and trapping it in an interlinked network of shallow ponds where the sun evaporates most of the water. As soon as the brine reaches its saturation point, salt crystallisation occurs. Several factors influence this mining process, each with a degree of variability that results in a risk factor owing to uncertainty. This study proposes a two-stage stochastic programming model, called 'a recourse model', that maximises salt crystallisation while providing solutions that are hedges against uncertainty. First, the theoretical background on optimisation theory is provided, followed by an overview of the mining processes. Second, the recourse model is verified and validated using historical data and comparing the results with its deterministic counterpart. The main contribution of this study is the formulation of the recourse model and the value that this approach adds when dealing with uncertainty in any decision-making process. [ABSTRACT FROM AUTHOR]

Communities and authorities have been dismayed by globally recorded tailings storage facility (TSF) failures in recent years, which have negatively affected the safety of people and the integrity of the environment. In this context, obtaining the social and environmental license to operate TSFs has become a challenging process for mining companies. This has promoted the trend of using mine tailings dewatering technologies in the mining industry, with dry stacking of filtered mine tailings being recognized worldwide as one of the most acceptable, safe, and environmentally friendly solutions. This article presents a new paradigm in managing mine tailings, with disruptive and futuristic characteristics, considering the dry stacking of filtered mine tailings for large-scale industrial production rates over 100,000 metric tons per day (mtpd). Aspects of filtered tailings management are discussed, such as (i) dewatering process plant with thickening/filtering equipment, (ii) conveyance using fixed and movable conveyor belts, (iii) construction of dry stacking of filtered mine tailings facility, and (iv) implementation of Industry 4.0 technologies for automation of the mining processes. Finally, the article discusses how the large-scale filtered mine tailings solution is applied, considering the advances in the equipment's performance and implementation of Industry 4.0 technologies as well as the experience gained worldwide in several mining operations. The future global trend is that mining operations with high daily production of mine tailings will apply dry stacking technology without dams to guarantee sustainability, promote continuity of the mining business, ensure the safety of communities, and conserve the environment. [ABSTRACT FROM AUTHOR]

In the field of multi-attribute group decision-making (MAGDM), "decision-making trial and evaluation laboratory" (DEMATEL) is a popular method that has been deployed to discover hidden relationships among many inter-twined factors of numerous real-world problems. This paper discusses several limitations of the DEMATEL method in mining the causal relationships and ranking the factors. Also, in this paper, we develop a novel decision-making framework that will be able to overcome the issues found in the DEMATEL method and tackle both formal and informal decisions. This model, which we call "Causal Relationship and Ranking Technique (CRRT)", uses a data-deterministic expert weighing setup rather than assigning equal weights or pre-defined weights to each expert. The model proposes a better technique to mine factor inter-relations and proposes two new types of digraphs portraying the causal inter-relationships among the factors, and also proposes a new two-step factor ranking method based on the derived causal relationships. The intuitionistic fuzzy setting is considered in this work in order to capture the uncertainty of expert opinions. Furthermore, our proposed framework is applied to a real-life case study on discovering various factors of a high school administration, that have a significant influence on students' performance. Comparison with standard methods such as TOPSIS and VIKOR for student performance data and also some other datasets such as supplier selection data, and sustainability data proves that the model is able to rank the factors better than the existing models. [ABSTRACT FROM AUTHOR]

Due to the particularity of the occurrence characteristics of shallow multiseam mining, underground mining space is vulnerable to obvious roof behaviors and serious gas anomalies, which are closely related to the destruction and migration characteristics of the overlying strata, the characteristics of the overlying-strata-bearing structure, and the permeability distribution of the broken interlayer under the influence of the overlying-strata-bearing structure. However, the related research is still insufficient. In this work, the discrete-element method (DEM) numerical model was used to simulate the entire process of the continuous mining of a shallow multiseam. In addition, the gas migration and its distribution in the lower mining field, under the influence of low-oxygen (O2) gas intrusion into the upper goaf, and the air leakage flow in the working face were studied using a Particle-Flow Code (PFC)–COMSOL coupling method. The results showed that the main feature in the evolution of the overlying-strata-bearing structure was the dynamic change in the supporting relationship between the collapse area and the surrounding rock, which changed from complete support to local force conduction, and finally complete separation under continuous mining in the upper and lower coal seams. The load distribution of the coal-seam floor presented a continuous change from surrounding rock to inside the goaf, with the breaking angle of the overlying strata being the key influencing factor. The conjoint analysis of stress and porosity indicated that the load under the overlying-strata-bearing structure determined the permeability distribution of the broken interlayer, which gave the gas in the goaf obvious distribution characteristics. [ABSTRACT FROM AUTHOR]

The paper analyzes the positive and negative aspects of various technological solutions for the liquid brines used during the development of polymineral potash ore deposits and considers the problem of determining the choice of the optimal approach by considering geological, technical, environmental, and financial factors. The study of the issues of utilization and reduction of the liquid brines components of discharges in the production of potash fertilizers, the simultaneous reduction of valuable components loss with liquid discharges, and, due to this, increasing the production of potash fertilizers, and the usage in the technology of mine brines, are an urgent and important scientific and engineering challenge of the potash industry. Technologically, several alternative solutions can reduce the number of liquid by-products placed in sludge storage. The work used analytical methods, including statistical data processing, modeling, pre-design studies of technological solutions, and assessment of economic costs. Excess brines of potash mining and processing plants are liquid waste obtained during the production of potash fertilizers – MOP и SOP. The accumulation of excess brines in sludge storage facilities is estimated at millions of cubic meters per year. However, the expansion of the sludge storage facilities area and the construction of dams are only temporary solutions. They are associated with risks in the design, construction, and operation of hydraulic structures, increasing the risks of brine leakage into open and underground water basins. Therefore, it makes it necessary to use other methods of brine disposal. Depending on the nature of the processed polymineral potash ores, several methods can be combined to dispose of excess brines at once: backfilling, osmosis, injection into deep horizons, and multistage evaporation. The most optimal combination of brine reduction technologies for potassium-magnesium processing plant's raw materials is the following: 60% is disposed of by usage of vacuum evaporation units, 20 % by injecting excessive brines into deep absorbing horizons, and 10%—20% should be used for backfilling or additional products production. [ABSTRACT FROM AUTHOR]

Induced polarization (IP) is a common method in ore exploration. IP spectra measured over a wide frequency range can be used to characterize material properties of ores, slags and other residual material from mines and processing facilities. Previous studies have shown that IP parameters are sensitive to type, content or grain size of electronically conductive or semi-conductive minerals. Up to now, a variety of experiments has been performed on sand mixtures with fractions of ore minerals. Most experiments consider only a single fraction with a fixed grain size. We continue a series of experiments that have been done with sand–pyrite mixtures. The presented study compares IP spectra recorded for samples either with a single grain radius fraction (E-samples) or with two different grain radii fractions (Z-samples). The spectra are fitted to Pelton models. A Debye decomposition that provides a relaxation time distribution (RTD) is applied to the complex conductivity spectra. The RTD indicates separated maxima only if the ratio of mean grain radii is larger than a factor five. The resolution of the phase spectra and the spectra of imaginary part of conductivity is lower. Even though the volumetric pyrite content is equal in each fraction, the phase spectra and RTD of the Z-samples indicate much higher signals for the pyrite fraction with smaller grain radius. The same observation is made for the chargeability that shows larger values for decreasing grain radii. This finding contradicts existing theories that consider the chargeability as a suitable proxy of the volumetric content of ore minerals. We explain the observed effect by an interaction between neighbouring pyrite particles. The conductivity of the mixtures of the E-samples increases with decreasing grain radius of the pyrite fraction. This effect is attributed to dissolution effects on the surface of the pyrite particles during the sample preparation. We find that the additive superposition of the phase spectra of two E-samples is in good agreement with the measured phase spectra of the Z-samples (measured superposition) containing the two corresponding pyrite fractions. The agreement is slightly worse for the spectra of imaginary part of conductivity, where the measured superposition overestimates the mathematical superposition. The experimental results of our study motivate a further improvement of existing mechanistic models. [ABSTRACT FROM AUTHOR]

Sampling is an important tool for gathering information about mineral deposits, helping to estimate the ore grade, and has great relevance at any stage of a mining project, to ensure reliable results and consequently, to project a better mining planning. There are several errors to which the sampling is exposed and among them we can mention the fundamental sampling error (FSE). This error cannot become zero as it is related to the constitutional heterogeneity of the ore, so it represents the minimum sampling error. This study applies Pierre Gy's theory of sampling (TOS) to estimate the values of K and a sampling constants at different deposits of bauxite in Brazil and compare them with the calculated factors, then calculate the relative standard deviation of the fundamental sampling error s(FSE) based on the results of the heterogeneity test (HT) in each deposit. The deposits are located in: Barro Alto - State of Goiás, Juruti - State of Pará, and Poços de Caldas - State of Minas Gerais. The weathering process is the main reason of the alteration of the physical and chemical factors diversifying bauxites in Brazil and worldwide. However, when sampling is carried out correctly, the Gy's formula becomes a powerful tool for improving mining processes as long as the factors are estimated correctly for each ore. [ABSTRACT FROM AUTHOR]

Mine safety evaluation (MSE) is a complicated engineering problem that may contain the truth, falsity, and indeterminacy information. In the process of mine safety evaluation, the linguistic neutrosophic multivalued information can conveniently express the truth, falsity, and indeterminacy linguistic values and satisfy the thinking and expression habits of decision makers. Then, existing probabilistic linguistic neutrosophic decision-making methods are difficult to reveal the real probability values in several linguistic evaluation values. To reasonably simplify the expression and operation of the linguistic neutrosophic multivalued information and overcome the defects of the probability methods, the aim of this study is to propose a safety evaluation method of mines using correlation coefficients of consistency linguistic neutrosophic sets (CLNSs) in the setting of linguistic neutrosophic multivalued sets (LNMVSs). To do so, this study first defines LNMVS based on truth, falsity, and indeterminacy linguistic multivalued sequences with identical and/or different linguistic values, and then proposes a transformation method from LNMVS to CLNS based on the average values and consistency degrees (complement of standard deviation) of the linguistic multivalued sequences to reasonably simplify the information expression and operations of LNMVSs. Next, correlation coefficients between CLNSs and their MSE method are developed to solve MSE problems. By an actual example about the safety assessment of metal mines and relative comparative analysis, the evaluated results reveal that the proposed MSE method can reasonably and effectively deal with safety evaluation problems of the mines in the setting of LNMVSs. The proposed method can not only reflect the mean and consistency information of multiple language evaluation values and overcome the defect of unreasonable information generated by the probabilistic language method in small evaluation data, but also make evaluation results more effective and credible. [ABSTRACT FROM AUTHOR]

Sustainable development in coal mining requires a continuous and efficient method of coal extraction. Research shows that gob-side entries retained through roof cutting retained gob-side (RCGE) are vital for improving mining efficiency, enhancing coal recovery rates, and enabling continuous production. However, the mechanism of surrounding rock deformation during close-distance co-mining of coal seams with this technique is not yet clear. For the Jiaokou coal mine in China, due to an unreasonable stagger distance between upper and lower working faces, the gob-side entries retained at the 9102 tailgate and 10102 headgate experience severe rock pressure, leading to significant prop damage and a sharp reduction in the cross-section of the entry. This greatly hampers the reuse of these entries. To investigate this issue, we established a model to study the stress distribution of surrounding rocks at different stagger distances (20 m, 40 m, 60 m, 80 m, and 120 m) through numerical simulation and optimized the support parameters for the retained entries. Our research found that when the subsidence of the roof in the upper coal seam exceeds 0.74 m but is less than 1.33 m, there is sliding instability in the mining body. When the subsidence exceeds 1.33 m, the mining body will rotate and deform, causing significant mining pressure within the retained entry. A stagger distance of 40 m between the upper and lower working faces can reduce pressure on the face during the mining of the lower coal seam. Extensive field measurements of rock pressure revealed that the damage rate of the single column in the gob-side entries of the upper and lower coal seams does not exceed 5% and 1%, respectively. In summary, this study provides a practical method to reduce damage to entries during the mining process, thereby increasing the continuous production capability of the coal mine. This is critical for the sustainable development of coal mining. [ABSTRACT FROM AUTHOR]

Due to the complex and dangerous nature of underground industrial sites, there is an urgent need to improve practical teaching abilities. In this paper, a VR-based interactive teaching and practice environment is proposed for teaching mining equipment processes under laboratory conditions. This environment integrates a digitised design, a virtual simulation platform, and a VR interactive product operation. This VR interactive environment includes the structural cognition of mining equipment, the actual operating conditions, and the actual operation of electronic control. Moreover, this system integrates a series of virtual reality human–machine interaction hardware, so that the students can quickly learn the operating conditions and the states of the actual underground production. This system helps them comprehensively learn the mechanical, electrical, communication, control, and mining methods involved in the mining equipment. Finally, this system provides a virtual practice path for training innovative engineering technicians. [ABSTRACT FROM AUTHOR]

In longwall top coal caving (LTCC) mining methods, problems such as large deformations, loss of coal resources, and excavation relay out of balance are often encountered with the increased production in single mining panels. To address these problems, a novel non‐pillar coal mining technology in LTCC was used based on the equilibrium mining theory. This approach could cut off the stress transmission, eliminate the coal pillar, and retain the gob‐side entry. In this technology, the entry is first excavated along the roof of the coal, and then four techniques are applied to control the surrounding rock of the retained entry. The constant resistance and large deformation anchor cable are used to maintain the roof stability. The directional roof split blasting technique is adopted to separate the roof between the entry and gob. The blocking‐gangue support system (BGSS) is used to form the gangue rib lagging the mining panel. The temporary support system is applied to prevent the roadway from being affected by the dynamic pressure and prevented the BGSS from falling. Finally, the field monitoring results indicate that the surrounding rock of retained entry is stabilized at 200 m behind the working face. The deformation of retained entry is within a reasonable range at 180–190 m behind the mining panel. The results provide an important reference for the thick coal seam non‐pillar coal mining technology, specifically using this technology in LTCC panels. [ABSTRACT FROM AUTHOR]

In the process of mining belt transportation, various foreign objects may appear, which will have a great impact on the crusher and belt, thus affecting production progress and causing serious safety accidents. Therefore, it is important to detect foreign objects in the early stages of intrusion in mining belt conveyor systems. To solve this problem, the YOLOv4_GECA method is proposed in this paper. Firstly, the GECA attention module is added to establish the YOLOv4_GECA foreign object detection model in the mineral belt to enhance the foreign object feature extraction capability. Secondly, based on this model, the learning rate decay of restart cosine annealing is used to improve the foreign object image detection performance of the model. Finally, we collected belt transport image information from the Pai Shan Lou gold mine site in Shenyang and established a belt foreign body detection dataset. The experimental results show that the average detection accuracy of the YOLOv4_GECA method proposed in this paper is 90.1%, the recall rate is 90.7%, and the average detection time is 30 ms, which meets the requirements for detection accuracy and real-time performance at the mine belt transportation site. [ABSTRACT FROM AUTHOR]

The leaching of minerals is one of the main unit operations in the metal dissolution process, and in turn it is a process that generates fewer environmental liabilities compared to pyrometallurgical processes. As an alternative to conventional leaching methods, the use of microorganisms in mineral treatment processes has become widespread in recent decades, due to advantages such as the non-production of emissions or pollution, energy savings, low process costs, products compatible with the environment, and increases in the benefit of low-grade mining deposits. The purpose of this work is to introduce the theoretical foundations associated with modeling the process of bioleaching, mainly the modeling of mineral recovery rates. The different models are collected from models based on conventional leaching dynamics modeling, based on the shrinking core model, where the oxidation process is controlled by diffusion, chemically, or by film diffusion until bioleaching models based on statistical analysis are presented, such as the surface response methodology or the application of machine learning algorithms. Although bioleaching modeling (independent of modeling techniques) of industrial (or large-scale mined) minerals is a fairly developed area, bioleaching modeling applied to rare earth elements is a field with great growth potential in the coming years, as in general bioleaching has the potential to be a more sustainable and environmentally friendly mining method than traditional mining methods. [ABSTRACT FROM AUTHOR]

Open pit mining is an effective way to extract valuable minerals from the earth's crust and generate significant profits for mining companies, however it also causes significant environmental harm to vast tracts of land and the surrounding ecosystems. However, the maximization of economic benefits is still the overall objective of optimizing open pit mine design, while environmental issues have been ignored in attempts to achieve more sustainable mine development. Therefore, estimating ecological costs of mining and considering such costs in the mine design process is an important step towards reducing ecological consequences at the design stage. The aim of the study is to calculate the ecological costs of open-pit coal mining and analyze how these costs affect the ultimate pit delineate. The ecological costs associated with coal mining are calculated according to the carbon emissons from energy consumption and the scope of grassland destroyed by resource extraction. There are three key components of ecological cost that have been identified: ecological service value loss, reclamation cost, and carbon emission cost. Necessary equations are provided for estimating these costs. An iterative optimization algorithm is described for ultimate pit optimization in coal deposits with near-horizontal coal seams. A case study is presented in which the ultimate pits are optimized by both with and without considering ecological costs, and compared to prove the impact of ecological costs on the ultimate pit design. [ABSTRACT FROM AUTHOR]

In this study, extremophile fungal species isolated from pure loparite-containing sands and their tolerance/resistance to the lanthanides Ce and Nd were investigated. The loparite-containing sands were collected at the tailing dumps of an enterprise developing a unique polar deposit of niobium, tantalum and rare-earth elements (REEs) of the cerium group: the Lovozersky Mining and Processing Plant (MPP), located in the center of the Kola Peninsula (northwestern Russia). From the 15 fungal species found at the site, one of the most dominant isolates was identified by molecular analysis as the zygomycete fungus Umbelopsis isabellina (GenBank accession no. OQ165236). Fungal tolerance/resistance was evaluated using different concentrations of CeCl3 and NdCl3. Umbelopsis isabellina exhibited a higher degree of tolerance/resistance to cerium and neodymium than did the other dominant isolates (Aspergillus niveoglaucus, Geomyces vinaceus and Penicillium simplicissimum). The fungus began to be inhibited only after being exposed to 100 mg L−1 of NdCl3. The toxic effects of Ce were not observed in fungus growth until it was subjected to 500 mg∙L−1 of CeCl3. Moreover, only U. isabellina started to grow after extreme treatment with 1000 mg∙L−1 of CeCl3 one month after inoculation. This work indicates, for the first time, the potential of Umbelopsis isabellina to remove REEs from the loparite ore tailings, making it a suitable candidate for the development of bioleaching methods. [ABSTRACT FROM AUTHOR]

A large number of residual ores in the intermediate pillars, crown, and sill pillars left by the shrinkage mining process adopted in the upper deposit of Chaihulanzi Gold Mine are highly economically valuable.To further improve the utilization rate of residual ore resources, this paper based on the existing scheme of the mine proposes 4 overall mining technology schemes for residual ore resources.Based on ABAQUS numerical simulation software, the corresponding numerical simulation model is established.The size striking direction extends 420 m, the vertical direction 616 m, and the height 160 m; the width of the surrounding rock is 50 m.The recovery rate, displacement field, and surface subsidence of different schemes were obtained, and the optimal technical extraction scheme was finally determined to be the horizontal and vertical striped evenly supported ore pillar extraction scheme through comparative analysis.The results show that in actual production, the scheme can maximize the economic benefits under the condition of safe mining while recovering the residual mineral resources under the non-cemented waste rock filling body. [ABSTRACT FROM AUTHOR]

The wear characteristics and related mechanisms of the Longwall Shearer Haulage System were investigated. Wear is one of the main reasons for failures and downtimes. This knowledge can help solve engineering problems. The research was carried out at a laboratory station and a test stand. The publication presents the results of tribological tests carried out in laboratory conditions. The aim research was to select the alloy intended for casting the toothed segments of the haulage system. The track wheel was made by the forging method using steel 20H2N4A. Haulage System was tested on the ground using a longwall shearer. Selected toothed segments were subjected to tests on this stand. The cooperation of the track wheel and toothed segments in the tootbar were analyzed by a 3D scanner. Debris chemical composition was also appointed, as well as mass loss of toothed segments. The developed solution toothed segment an increase in the service life of the track wheel in real conditions. The results of the research also contribute to reducing the operating costs of the mining process. [ABSTRACT FROM AUTHOR]

The re-mined face using top coal caving system is the most applicable method for recovering the remaining reserves of a previous partially-mined thick coal seam. However, this mining method may encounter the problems of low recovery and unpredicted geological conditions. A numerical model is developed using PFC2D for studying the movement of top coal mass and development of coal-rock mass interface at a longwall top coal caving re-mined face. The re-mined face advances in the lower seam below the upper solid coal pillar, previous entries and gob. A theoretical analysis according to the unsteady flow model is developed to calculate the proper time duration of caving operation. The results showed that the top coal to be recovered through the caving window before the initiation of caving operation is a partial spheroid-shaped geometry. The boundary between the coal and rock mass then develops to a funnel-shaped coal-roof interface as the caving operation continues. The top coal recovery is 98.1%, 77.1% and 70.5% for caving operations below the solid coal, entries and gob area in the upper seam, respectively. The proper timing of caving and interval of caving operation is important for obtaining a high coal recovery. Good agreement is achieved between the proposed model and the improved Boundary-Release model for short of B-R model. The study in this work may provide reference for the safety and efficiency of the extraction of the longwall top coal caving re-mined face. [ABSTRACT FROM AUTHOR]

The prediction and control of roof water disaster has been one of the key problems in the mining process of coal resources. With the increase of mining depth in the western mining area, the roof caving and communicating to the overlying water-bearing strata have led to an increasing number of roof water inrush accidents and deterioration of production environment of the working face. Aiming at the problem of roof water disaster prediction of sandy-argillaceous structural strata in Shanghaimiao mining area in China, firstly, the mechanical structure model of roof water inrush was built according to the parameters in the advance of the working face, and the thickness of the sandstone was used as the main controlling geological factor; the formula was derived for calculating the water-rich intensity F zh of the overlying strata in the mining area. Secondly, starting from the height of the "Breakage-arch" development disturbance by combining the mechanical structure model of roof water inrush, the relative positional relation of the "Breakage-arch" and the water-bearing strata was analyzed, and a new method for judging the risk coefficient T W of roof water inrush was proposed. Finally, according to the geological drilling histogram and the field conditions of #111084 working face of the no. 1 mine in Shanghaimiao mine area, the water-rich index and water inrush risk coefficient of overlying water-bearing strata were obtained by means of discriminant analysis, and the water inrush risk of #111084 working face was evaluated and predicted quantitatively. The water-rich property evaluation of water-bearing strata under the condition of low degree of hydrogeological exploration was evaluated accurately and reasonably, and a new evaluation method of the water disaster during mining was proposed. [ABSTRACT FROM AUTHOR]

With the increase of mining depth, disaster degree of rock burst in fault-controlled area is becoming more and more serious. To analyze mechanism and control method of fault rock burst, No. 3316 mining face controlled by No. 3DF56 fault in Jining mine, China, is selected as case study. First, by analysis of general situation of the mining face, mechanical characteristics of coal rock, and micro-seismic events, it is determined that the coal seam has the possibility of rock burst in the process of the face mining towards the fault. Second, based on strength theory of rock, criterion of fault shear instability is obtained, and influence of cohesion and friction angle on the stability of fault is analyzed, and it is concluded that improving the cohesion of rock can control the fault slip. Third, by borehole detection recorder, it is determined that fracture areas of fault surrounding rock distribute in the range of 0–4 m from the surface of roadway surrounding rock and 0–5.0 m from the fault. Finally, control method of "precise grouting to couple shallow and deep boreholes" is introduced, and the grouting borehole scheme is optimized. Field test results show that the method can improve the compressive strength of coal rock and distribution laws of micro-seismic events, weaken the possibility of fault slip, effectively control the deformation of roadway surrounding rock and improve the control effect of rock burst. It can provide a reference for other coal mines with similar geological conditions. [ABSTRACT FROM AUTHOR]

The Malogne Phosphatic chalk quarry was developed by the rooms and pillars mining method within an area of 67 ha. The site is partially flooded and located in close proximity to important infrastructure as railway, highway, and residential houses. During and after its exploitation several significant ground collapses were registered. The last one, with an area of 1.2 ha and 3 m amplitude occurred in 2015 nearby the railway line. To assess the behavior of the underground openings a combination of in situ structural measurements and laboratory mechanical characterisation in dry and saturated state of the main lithology type in the quarry – white and phosphatic chalk, hard ground and calcarenites, are performed. The UCS of the chalk ranges from 4 to 10 MPa while its tensile strength is between 0.75 and 2.1 MPa. For the hardground, these values are over ten times higher. The results reveal significant influence of the water on the chalk properties by reduction of almost twice its strength. The data obtained was implemented in a conceptual geomechanical model, using the 2D FEM. Numerical results show a failure pattern that was confirmed from the in situ observations. [ABSTRACT FROM AUTHOR]

The longwall mining method with gob-side entry retaining via roof cutting is a new underground coal mining method which has the characteristics of a high resource recovery ratio and environmental friendliness. Due to the complexity of this method, the research method of case-based dynamic on-site monitoring, analysis, adjustment, and optimization is usually adopted. Based on a roadway retaining via roof cutting project, in addition to the traditional indirect monitoring method of hydraulic support pressure, this study innovatively establishes a direct monitoring method for roof caving by monitoring the gangue pressure in the goaf, which provides data for the roof cutting effect and offers a new method for studying the overlying strata movement. In the project, a comprehensive monitoring and analysis system was established, including gangue pressure, cable bolt stress, bracket pressure, roadway deformation, and roof separation, which was used to dynamically analyze the effect of roof cutting and optimize the support design. The results show that the pressure of the hydraulic support close to the roof cutting is low, indicating that roof cutting is favorable in the roadway retaining mining method. The roadway deformation in the advanced abutment pressure area of the working face is small. The mining-induced stress caused by the collapse and compaction of the overlying strata in the goaf is the dominant factor affecting the effect of roadway retaining, especially in the 50–100 m range behind the working face, where the dynamic load causes high bearing capacity of the support elements, large roadway convergence, and roof separation. Temporary support and supplementary reinforcement should be added when necessary. The monitoring system presented in this study is highly comprehensive, simple, reliable, and low in cost, providing a reference for roof cutting roadway retaining projects and roof caving-related studies. [ABSTRACT FROM AUTHOR]

The destructive failure of Shanghai Metro line 4 across underneath the Huangpu River on July 1, 2003, led to massive ground subsidence and collapse of pre-existing structures in the proximity; additionally, the failure generated large amounts of human-made rigid obstructions in the strata, which made rehabilitation of the collapsed metro line be very technically challenging. By extensive comparisons in terms of technical difficulties, economic costs, and construction durations, a plan of reconstruction of the collapsed metro line at its original location rather than relocation was selected finally for the postfailure rehabilitation. The majority of the failed metro line was replaced by a 262-m-long×23.7-m-wide×38.5–41.2-m -deep cut-and-cover tunnel bottoming out in the confined aquifer, whose two ends were connected with the existing intact metro line via two 10-m-long tunnels mined within the aquifer by the ground-freezing method. Excavation of the cut-and-cover tunnel was retained by 1.2-m-thick and 65-m-high perimeter diaphragm wall panels braced by 9–10 levels of steel-reinforced concrete struts. To ensure the project safety and mitigate potential adverse influences of field works on the urban environments, extensive innovative construction plans, measures, and techniques were designed and then implemented into the reconstruction, e.g., a lightweight cofferdam and pile-supported steel platform for diaphragm walling through the existing metro line underneath the river; unique protective solutions and construction techniques for execution of vertical and horizontal ground-freezing programs for diaphragm walling and mining; special procedures of cleaning up the existing tunnels previously filled with water, sand, and cement; innovative joints and grouting measures adopted between the reconstructed tunnel and the pre-existing intact metro line, and so on. Furthermore, the initial designs were optimized and adjusted with the progress of field construction works. Lastly, the long-term field performance data demonstrated the success of this rehabilitation project, which affected the urban environments rarely. The construction plans, measures, and techniques outlined in this paper are practical, useful references for professionals worldwide to deal with similar underground projects in the future. [ABSTRACT FROM AUTHOR]

This study reveals the hydrocarbon production potential and thermal maturity of Çilhoroz coals, which is the most important local coal field around Erzincan in the Eastern Anatolia Region. This area is one of the best examples of the continental collision zone in the world and is located in a north-south convergent collision zone between the Eurasian and Arabian Plates. The average thickness of the coal seam is about 4 m and these coals are currently mined by open pit mining methods. Coal is predominated by combined xylitic/attrital lithotypes and by huminite macerals with inertinite and minor liptinite macerals. The content of mineral matter is variable but generally low, it consists mostly of quartz, calcite, clay minerals, and pyrite. Although the Rock-Eval pyrolysis data show that the investigated coal bearing unit is represented by a significant hydrocarbon (oil and gas) potential, hydrocarbon species did not develop due to low maturation. [ABSTRACT FROM AUTHOR]

Mass mining methods such as block and panel caving are more commonly being utilized to generate value from deep, low-grade ore deposits. In addition to mining deeper and encountering higher in situ stresses, these projects are also mining larger volumes in more competent rock masses, increasing their exposure to brittle rock failure mechanisms such as spalling and rockbursting. Rockbursting presents a health and safety risk for mine personnel, a financial risk for mine operators, and a significant design challenge for engineers. A methodology is proposed for recording, databasing, and performing data-driven assessments of rockbursting in cave mines with the goal of correctly identifying the damage mechanisms, the triggers, and important controlling factors. Novel databasing techniques and new indices are introduced that are specifically tailored to cave mining operations where the damage from rockbursts may be widespread across a large extraction-level footprint. A case study of the Deep Mill Level Zone (DMLZ) panel cave mine is presented to demonstrate the data-driven analysis techniques. Using the proposed indices and data analysis techniques, strainbursting was identified as the dominant rockburst damage mechanism in the DMLZ, with load redistribution from blasting and advance of the undercut and mining of the cave being identified as the main triggers. Contributing factors for the rockbursting in the DMLZ are discussed including the mining sequence, the mine geometry, and the geology. Evidence for veining heterogeneity contributing to increased susceptibility to strainbursting is presented, a key finding with practical implications for future mass mines. Highlights: Novel databasing techniques, indices, and assessments are introduced to identify the rockburst damage mechanisms, trigger mechanisms, and important controlling factors in a cave mining setting. Two distinct databases are proposed to track local excavation damage and the cumulative impact of widespread rockburst damage that is possible in large-scale mining. New indices are proposed including the Rockburst Damage Index and Rockburst Cluster Index that are practical and useful for data driven assessments of rockbursting. A methodology is presented using multivariate logistic regression and a grid cell system to study spatial susceptibility to rockburst damage in cave mining. The geometry of cave mining lends itself well to spatial modelling using the proposed grid system and the selection of mechanistically meaningful explanatory variables. The approach therefore combines robust procedures for logistic regression with data processing that is suitable for the cave mining environment, leading to highly interpretable results. A case study of the DMLZ is shown to demonstrate the value of the proposed assessments. Key findings from the DMLZ include the identification of strainbursting as the dominant damage mechanism, the important role of veining intensity in strainburst susceptibility, and the positive role of a deformation-based ground support design in suppressing low severity strainbursting. [ABSTRACT FROM AUTHOR]

The optimal selection of stope structure parameters has important significance to mining safety and mining benefits. The sublevel open stoping with subsequent filling mining method was used at the copper mine in Shangri La county, Yunnan province, according to the mechanical parameters of the rock mass and the filling body and the layout characteristics of the stope, the FLAC3D numerical software was used to establish the stope model and 16 different stope structure parameter schemes were designed by orthogonal design test, and the stability analysis of all schemes was carried out, and the comprehensive evaluation model of FAHP CRITIC method combined weighting was established to obtain the optimal parameter and the optimal filling ratio. The scheme is popularized in each middle section of the mine and a good reference significance for the stope test of similar mines. [ABSTRACT FROM AUTHOR]

A gold — copper mine in Xinjiang is located at a high altitude. The industrial site is limited, with complex terrain and a sensitive environment. The distance between the dressing plant and the tailings pond is long and the height difference is significant. Under the conditions of simultaneous mining of upper and lower mining areas and coexistence of self-flow and pumping, to fully balance underground filling and tailings conveying and achieve green mining of mines, the paper, based on the development system, established the optimal thickening method for mine tailings filling and proposed 3 feasible solutions for the coordination of tailings conveying and filling system layout, which are compared and analyzed from multiple aspects including process flow, engineering investment, operating costs, and surface environment protection. The results show that the mine is most suitable for the deep cone thickening scheme, and the filling station is arranged at the surface of 2800 m air return audit + two-stage tailings conveying( Scheme I ), which is obviously better than Scheme II and III in terms of investment, operating costs, present value cost, and reliability. Besides, the system has high reliability and is easy to manage. The research provides solutions for the construction of tailings conveying and filling systems of the same type of mine. [ABSTRACT FROM AUTHOR]

The target of this study was the tungsten Regoufe mine, whose exploitation stopped in the 1970s. When the mine closed, an unacceptable legacy constituted of mining waste tailings and the ruins of infrastructure was left behind. This work assessed the soil, plants, and water contamination in the mining area; namely their content in potentially toxic elements (PTEs). The global impact of PTEs in the Regoufe mine surface soil points to a very high to ultrahigh degree of contamination of the area having a serious ecological risk level, mainly related to As and Cd contributions. However, establishing the direct relation between As contamination and the anthropogenic effects caused by the mining process cannot be carried out in a straightforward manner, since the soils were already enriched in metals and metalloids as a result of the geological processes that gave origin to the mineral deposits. The studies performed on the plants revealed that the PTE levels in the plants were lower than in the soil, but site-specific soil concentrations in As and Pb positively influence bioaccumulation in plants. The magnetic studies showed the presence of magnetic technogenic particles concentrated in the magnetic fraction, in the form of magnetic spherules. The magnetic technogenic particles probably result from temperature increases induced by some technological process related to ore processing/mining activity. The PTEs in the surface and groundwater samples were similar and relatively low, being unlikely to pose potential health and environmental risks. Arsenic (As) constituted the exception, with levels above reference for drinking water purposes. [ABSTRACT FROM AUTHOR]