Mining Section Research Articles

New zircon U-Pb age of the top Duoni Formation, Basu County: constraits on the collision between Qiangtang and Lhasa blocks in Eastern Tibet

The Duoni Formation is widely distributed along the Bangong-Nujiang suture belt and surrounding blocks in Tibet, serving as a key sedimentary record of the collision between the Qiangtang and Lhasa blocks. The upper sections of the formation typically contain andesite, volcanic rocks and tuff offering potential for precise stratigraphic correlations across the suture belt. The Duoni Formation in the central and western belt has been well-constrained geochronologically through zircon U-Pb dating; however, the insufficient age constraints on Duoni Formation in eastern Tibet hinder effective stratigraphic correlation and limit the understanding of the timing of this collision. Building on prior stratigraphic and paleontological studies, we collected three tuff samples from the upper Duoni Formation at the Wada coal mine section in Basu County, eastern Tibet. Zircon U-Pb dating was used to determine the age of the Duoni Formation, yielding results of 112.8 ± 1.0 Ma for sample XZ01, 111.48 ± 0.37 Ma for sample XZ03, and 110.95 ± 0.41 Ma for sample XZ05. These absolute ages correspond with early Albian and are generally consistent with those absolute ages from the central and western suture belt. Our study therefore suggests the similar timing for the Qiangtang-Lhasa collision across the whole Bangong-Nujiang belt.

Pollution Assessment and Source Apportionment of Heavy Metals in Sediments of Subsidence Section of Luling Mine in the Tuohe River, China

Pollution Assessment and Source Apportionment of Heavy Metals in Sediments of Subsidence Section of Luling Mine in the Tuohe River, China

Mineralization based on CSAMT data: A case study on the Gaoloushan section of Yangshan gold belt

AbstractYangshan gold belt (YSGB) in Gansu Province is a super‐large orogenic gold deposit located in the middle section of the Mianxian‐Lueyang arcuate suture zone (Mian‐Lue suture zone). The YSGB is mainly divided into the Gejiaowan, Anba, and Gaoloushan mine sections. The ore veins are strictly controlled by strong strain zones in the fracture zone and secondary fractures superimposed on the inherited activity and are vein‐like in general and lenticular in localities. For a long time, there have been different understandings regarding its ore‐controlling factors and mineral genesis. By utilizing controlled‐source audio‐frequency magnetotellurics (CSAMT) technology to conduct electrical characteristic studies, the deep electrical structural characteristics of the Gaoloushan section are identified, and a tectonically‐controlled geoelectric model of the deposit is established, which provides geophysical evidence for the view that the Yangshan gold mine is a tectonically‐controlled low‐temperature hydrothermal deposit in altered rock, guiding the arrangement of exploration work and identifying prospective mining areas, and thereby providing a geophysical exploration paradigm for deep exploration of large orogenic gold deposits.

Study on the Damage Mechanism of Coal under Hydraulic Load

Hydraulic fracturing is extensively utilized for the prevention and control of gas outbursts and rockbursts in the deep sections of coal mines. The determination of fracturing construction parameters based on the coal seam conditions and stress environments merits further investigation. This paper constructs a damage analysis model for coal under hydraulic loads, factoring in the influence of the intermediate principal stress, grounded in the unified strength theory analysis approach. It deduces the theoretical analytical equation for the damage distribution of a coal medium subjected to small-flow-rate hydraulic fracturing in underground coal mines. Laboratory experiments yielded the mechanical parameters of coal in the study area and facilitated the fitting of the intermediate principal stress coefficient. Leveraging these datasets, the study probes into the interaction between hydraulic loads and damage radius under assorted influence ranges, porosity, far-field crustal stresses, and brittle damage coefficients. The findings underscore that hydraulic load escalates exponentially with the damage radius. Within the variable range of geological conditions in the test area, the effects of varying influence range, porosity level, far-field stress, and brittle damage coefficient on the outcomes intensify one by one; a larger hydraulic load diminishes the impact of far-field stress variations on the damage radius, inversely to the influence range, porosity, and brittle damage. The damage radius derived through the gas pressure reduction method in field applications corroborates the theoretical calculations, affirming the precision of the theoretical model. These findings render pivotal guidance for the design and efficacy assessment of small-scale hydraulic fracturing in underground coal mines.

Using isotope-geochemical criteria for Olympiadinskoye gold deposit gas system genesis diagnosis

The authors studied modern gas manifestations spatially associated with the ore deposits in the Kaitbinskaya lithological-facies zone of the Yenisei Ridge. The purpose of the research is to obtain scientifically based data on the genesis of gaseous and vaporous fluids in various sampling environments of the Vostochny open-pit mine of the Olympiadinskoye gold deposit: rocks, natural waters, free-flowing gases from blastholes and air of the surface atmosphere. It has been conducted a complex of field and analytical works including degassing, gas chromatography, pyrolysis of the organic substance of lithified and metamorphosed deposits, analysis of carbon isotopic composition in carbon dioxide and methane in fluidal systems. In order to study normal gas-geochemical field (natural background) of the work area an atmospheric geochemical survey was carried out at the reference site – an “environmentally friendly” site with the minimal influence of technogenic factors. It has been determined that the surface atmosphere of the site had been formed due to the landscape and geomorphological conditions of the Kaitbinskaya lithological-facies zone as well as fluidal systems of deep horizons. The latter, due to the presence of an extensive network of disruptive disturbances and diffusion-filtration processes of mass transfer reached the zone of exploratory geochemical sounding. The conducted pyrolytic studies of rocks have proved that within the open section of the Vostochny open-pit mine the organic substance of the Kordinskaya series of the lower Riphean deposits has implemented its oil and gas generation potential and cannot serve the formation source of abnormal gas fields of the Olympiadinskoye gold deposit. The studied gas systems are polygenic in nature and, being allochthonous to the host sediments, are formed without the participation of gases from the upper generating (bio) zone. According to isotope-geochemical criteria, these are mainly endogenous and naphthidogenic fluids identical to the gas condensate accumulations of the Yurubcheno-Tokhomskaya oil and gas accumulation zone.

Stability Evaluation of the Goaf Based on Combination Weighting and Cloud Model

Goaf has become one of the most significant sources of hazard affecting the safety of metal and nonmetal mines. Evaluation of goaf stability is of paramount importance for mine safety production. First, 13 indices such as rock mass structure, geological structure, and goaf volume are selected based on engineering experience and literature review to assess the stability of goaf. These indices are classified according to the characteristics of each factor, and a stability evaluation system for underground mine goaf is constructed. Second, the analytic hierarchy process method based on group decision theory is utilized to calculate the subjective weight of each index. Additionally, the CRITIC method is used to calculate the objective weight of each index. Finally, game theory is used to combine the subjective and objective weights, thereby improving the accuracy of the index weight. The stability grade of the goaf is calculated using the normal cloud model. The FLAC3D numerical simulation is used to analyze the stability of the goaf and verify the accuracy of the model. The abovementioned model is utilized for assessing the stability of the goaf in the Duimenshan mine section. The results indicate that 90% of the goaf area is in a stable or relatively stable condition, while the remaining 10% is unstable. The evaluation outcomes were compared with FLAC3D numerical simulations, highlighting a scientific and reliable method with an accuracy rate of 90%.

A bootstrap strategy to train, validate and test reduced order models of coupled geomechanical processes

This paper presents an approach for developing Reduced Order Models (ROMs) of complex geomechanical systems from high-fidelity numerical simulations. The approach uses proper orthogonal decomposition of the state variables for the model reduction, combined with long short-term memory neural networks to update the simulations in response to changing boundary conditions. A key challenge in creating these models is the need to efficiently sample the system state during training and testing. Too few (or poorly distributed) training simulations yields inaccurate models, while too many results in wasted effort. However, the exact number required is difficult to determine ahead of time, as it is both context and model dependent. Here, we present a bootstrap strategy to estimate the number of simulations required to develop the reduced order model. The strategy uses an iterative approach in conjunction with a quasi-random sampling technique to ensure consistent coverage of the sample space. We demonstrate the approach by developing a ROM describing the coupled hydro-mechanical response of a section of an open-cut coal mine. Excellent agreement is achieved between the resulting reduced order model and the original high-fidelity simulation for significantly less computational effort.

Instability mechanism of overlying strata in a shallow interval goaf and structural model of the “W-shaped voussoir beam”

Abstract To study the failure mechanism of overlying strata (OS) in shallow insufficient mining areas, with a combination of such research approaches as field investigation, theoretical analysis, similarity simulation, and numerical simulation, this paper studies the temporal and spatial evolution of the failure mechanism of overlying stratum structure in a shallow-buried interval goaf. The results show that the creep failure of temporary coal pillar (TCP) in the interval goaf is a primary reason for the failure of the basic roof. With the failure of the basic roof, stress arches in the OS of the mining section become unstable, which expands the damage range of the overlying strata. Consequently, adjacent stress arches overlap with each other, forming a “trapezoidal–semi-elliptical arch” collapse shape. Thick soil layers gradually collapse to the ground surface, and the OS collapse as a whole into a trapezoid-like shape. Rotary failure appears in the basic roof of mining section, forming a W-shaped voussoir beam hinge structure. In this study, a structural model of a W-shaped voussoir beam in the OS is established, and the mechanical characteristics of rock blocks in the basic roof of overlying strata during different mining stages of the interval goaf are analyzed. Also, with a discrete element UDEC program, this study performs a simulation to verify the rationality of the W-shaped voussoir beam structural model of overlying stratum movement in the shallowly buried interval mining section.

Commercialisation pathway for low energy wet/dry gyratory rolls crusher comminution technology

Comminution for mining and cement industries accounts for over 2 % of global energy consumption and an innovative Gyratory Rolls Crusher (GRolls®) technology has been developed in South Australia to reduce energy and water consumption, providing dry and wet crushing from ∼ 20 mm to 20µm fractions without media, replacing up to two stages of size reduction. The GRolls® is a compression based particle size reduction device, designed to generate fine and ultra-fine products from coarse feeds, by simultaneously applying pulsed compression and shear forces to a packed particle bed. The breakage mechanisms initiated by these forces include compression breakage, inter-particle compression, induced tensile failure and particle shear forces generated by a gyrating roll.The paper presents the commercialisation pathway of the GRolls® technology, from “proof of concept” laboratory scale Alpha prototype and concept design of an upscaled Beta prototype for a pilot plant. A systematic progression of laboratory scale testing of a wide range of feed materials through the Alpha prototype was undertaken to confirm the ‘”proof of concept” design and identify the many design variables and operational configurations that affect the GRolls® crushing and energy performance. The test results were evaluated against currently available comminution solutions such as the High Pressure Grinding Rolls (HPGR) and Vertical Rolls Mill (VRM) in which the mining section is moving towards to provide more economical dry comminution and a progression towards partial to full dry process flowsheets.The commercialisation pathway has confirmed the broad performance range and energy consumption of the GRolls® which could be modularised in the near future to support new and existing low grade mining operations in remote areas restricted by limited water and power infrastructure.

A study of backfill confinement to reinforce pillars in bord-and-pillar layouts

This study explores the use of backfill in hard rock bord-and-pillar mines to increase the pillar strength and extraction ratio at depth. The use of backfill will also minimize the requirement for tailings storage on surface and the risk of environmental damage. A literature survey indicated that backfill is extensively used in coal mines, but rarely in hard rock bord-and-pillar mines. To simulate the effect of backfill confinement on pillar strength, an extension of the limit equilibrium model is proposed. Numerical modelling of an actual platinum mine layout is used to illustrate the beneficial effect of backfill on pillar stability at greater depths. The magnitude of confinement exerted by the backfill on the pillar sidewalls is unknown, however, and this needs to be quantified using experimental backfill mining sections equipped with suitable instrumentation.

Multiple regression method for working face mining pressure prediction based on hydraulic support monitoring dataset

Introduction: In the coal mining process, the intense mining pressure is an important factor hindering the safe and efficient production of the working face. In severe cases, it causes deformations in roadways such as roof breakages and rockbursts, and leads to instability. This can result in the roof falling over a large area and the coal wall, thereby inducing dynamic disasters. These aspects have restricted the economic benefits of coal.Methods: In this study, we set four model limitations based on the limited scope of action of the mining pressure itself and the quantitative relationships between mining pressures in different regions. A multiple linear regression model with these limitations is proposed for predicting the mining pressure for preventing roof breakages and rockbursts. Based on a hydraulic support monitoring dataset from a fully mechanized caving face of coal mining, the mining pressure prediction model is trained by using the first 70% of the dataset. And the linear regression coefficient of the model and the predicted value of the mining pressure are obtained. Then, the last 30% of the dataset was used for the validation of the model.Results: The research results show that the constrained multiple linear regression model can achieve remarkable prediction results. According to predictions of tens of thousands of on-site mining pressure datasets, the predicted data and actual pressure data have the same change trend and maintain a low relative error.Discussion: Therefore, after real-time mining pressure monitoring, the system obtains the roof pressure of the fully mechanized mining face. According to the dataset, the proposed prediction model algorithm quickly predicts the roof pressure value of the next mining section and effectively forewarns roof breakages and other accidents.

Haulage Cycles Identification for Wheeled Transport in Underground Mine Using Neural Networks.

The task of ore transportation is performed in all mines, regardless of their type (open pit/underground) or mining process. A substantial number of enterprises utilize wheeled machines to perform ore haulage, especially haul trucks and loaders. These machines' work consists of repeating cycles, and each cycle can be divided into 4 operations: loading, driving with full box/bucket, unloading and driving with empty box/bucket. Monitoring this process is essential to create analytical tools that support foremen and other management crew in achieving effective and optimal production and planning activities. Unfortunately, information gathered regarding the process is frequently based on operators' oral testimony. This process not only allows for abuse but is also a repetitive and tedious task that must be performed by foremen. The time and attention of foremen is valuable as they are responsible for managing practically everything in their current mine section (machines, operators, works, repairs, emergencies, safety, etc.). Therefore, the automatization of the described process of information gathering should be performed. In this article, we present two neural network models (one for haul trucks and one for loaders) build for detecting work cycles of the ore haulage process. Both models were built utilizing a 2-stage approach. In the first stage, the models' structures were optimized, while the second was focused on optimizing hyperparameters for the structure with best performance. Both of the proposed models were trained using data collected from on-board monitoring systems over hundreds of the machines' work hours and utilized the same input features: vehicle speed, fuel consumption, selected gear and engine rotational speed. Models have been subjected to comprehensive testing during which the efficiency and stability of the model responsible for haul trucks was proven. Results for loaders were not as high quality for haul trucks; however, some interesting facts were discovered that indicate possible directions for future development.

Study on Asymmetric Deformation Law and Surrounding Rock Control Technology of High Stress Soft Rock Crossing Roadway

In order to solve the problem of asymmetric large deformation of high-stress soft rock crossing roadway under complex geological conditions in deep mines, taking the 2# total return airway of 76.2# section of Wuyang Coal Mine as the engineering background, the causes of asymmetric deformation and failure of soft rock crossing roadway in deep mines were summarized and analyzed by means of field investigation, theoretical analysis and numerical simulation, and the asymmetric high-efficiency support technology with large row spacing was studied. The results show that the lithology of roadway strata is the main cause of asymmetric deformation and failure of roadway. The shape change of roadway is not the main influencing factor of asymmetric deformation of roadway, but for the control of roadway surrounding rock, the straight wall semi-circular arch roadway is better than the rectangular roadway. The field industrial test shows that after adopting the new support design scheme, the displacement of the roof and floor of the roadway is reduced by 86.39% compared with the original support design scheme, and the displacement of the two sides of the roadway is reduced by 86.05% compared with the original support design scheme, which can ensure the normal and safe production of the roadway during the service period, and provide reference for the support design of other similar geological conditions.

ASSESSMENT OF THE RISK OF LOSS OF STABILITY OF A SLOPE DRIFT IN THE DEVELOPMENT OF STEEP COAL SEAMS

Purpose. The purpose of the article is to assess the risk of loss of stability of the preparatory mine workings in order to adjust measures to prevent hazards and their consequences in the excavation areas of a coal mine with steep seams.. Method. An integrated approach was used, including: analysis and synthesis of known studies, expert evaluation, application of the basic principles of probability theory, processing, analysis and interpretation of the results. Results. During the examination of 7 objects (excavation sites), the a priori ranking identified significant factors that affect the loss of stability of preparatory mine workings. Accidental events were considered: the collapse of the roof, the slippage of the sole in the produced space of the coal massif, and the failure of fastening in the roll-back stretch. The ranking results are confirmed by the concordance coefficient (0,9). The analysis of accidents related to the loss of stability of the preparatory workings with different methods of protection allowed establishing the frequency of roof collapses and ground slides in the coal massif at the excavation site. To statistically evaluate the failures of the arch support ω in the working face, field studies were carried out. It was found that in the area of influence of the cleaning operations when protecting the heading with coal blocks, the failure rate of the arch support is ω=0.24, bushes from the racks ω=0,27, and wooden fires ω=0,16. Taking into account the combination of the identified significant factors, the a posteriori probability of loss of stability of the heading in the area of influence of the longwall face in the area of 10 ≤ l ≤ 45 m is 0,036-0,055 m when using coal blocks, 0,044-0,078 bushes from the risers and 0,0176-0,036 wooden fires. The probability of arch support failure is approximately 0,6. On the basis of research, a quantitative assessment of the component risks wa established, which leads to the loss of stability of the rollback stretch. The maximum risk assessment R = 576 corresponds to the conditions when the production is protected by bushes made of wooden risers. Scientific novelty Assessment of the risk of loss of stability of the preparatory mine workings is a set of research and analytical measures aimed at reducing the manifestation of hazards in the coal massif at the excavation sections of a coal mine. Practical significance. To obtain qualitative and quantitative estimates of the risk of loss of stability of the preparatory mine workings along the length of the excavation section, a model of formation of a possible dangerous situation was proposed. Key words: coal mine, preparatory workings, cave-in, side rocks, simulation modelling, miners’ safety.

An investigation of airflow distributions with booster fan for a large opening mine through field study and CFD modeling

In this study, we conducted a field survey for the large opening mine with the survey data serving as the numerical modeling inputs to investigate the booster fan airflow distribution using a computational fluid dynamics (CFD) model. A CFD model was created with a booster fan inside the model domain, the airflow distribution patterns around the booster fan were then examined to gain insights on the booster fans impact on the air distribution in the dedicated mining section. Based on the modeling results, the booster fan is an effective ventilation control for airflow direction in large opening mine and the booster fan placement can significantly influence the effectiveness of face pollutants’ removal through airflow recirculation. The fan can boost air velocity to create the multi-pillar scale airflow recirculation to dilute the extraction heading pollutants. Furthermore, the typical continuous traverse done by many mine operators, which only covering part of the entire cross section, may be inadequate around booster fans with errors ranging from 35% to 210%. The airflow calculated at the entry adjacent to the booster fan was 25% that of the fan setting with the subsequent entries exchange diminishing by ∼65.2% per entry indicating streamlining of airflow in the booster fan entry. While the geometry of the mine will play a significant role in determining the airflow distributions this study lays the groundwork for future studies on booster fan placement optimization and effectiveness for face ventilation.

Специфика заземления электрооборудования участка шахты в контексте соответствия критерию эффективности защиты персонала от электропоражения

The paper provides evidence that the existing standardized design concept of power supply systems for the mine sites inherently involves existence of an electrical shock hazard to humans when touching the phase of the network. This hazard is caused by the active and capacitive conductance of the insulation due to grounding of the central cores of the flexible shielded mining cables. The functional inefficiency of the ground fault protection used in the mining industry has been proved, including the cases of mine electric networks with high power consumption. An alternative concept was justified to design the power supply system for a mine section electric network, which excludes grounding of the central cores of the flexible cables. This approach implements the principle of selective shutoff protection of the electrical consumers in the mine section using local means to control the condition of insulation in the power connections.

Failure Mechanism and Stability Control Technology of Slope during Open-Pit Combing Underground Extraction: A Case Study from Shanxi Province of China

With the development of society, the demand for mineral resources is gradually increasing, and the current situation of decreasing total resources dictates the inevitable interaction between open-pit combing underground extraction (OPUG) in time and space. In this research, we took the Anjialing coal mine in Shanxi Province of China as a case study, and tested the physical and mechanical properties of coal rocks in the laboratory. The similarity criterion was used to build a similar experimental model for the deformation evolution of the slope of the open-pit mine section; the digital scattering method was used to test the influence of the underground mining process parameters on the deformation evolution of the open-pit slope. The results showed that there was an obvious distribution of “three zones” above the mining goaf, namely, a collapse zone, fracture zone, and slow subsidence zone. When the mining face was continuously advanced towards the bottom of the open pit, the supporting stress of the mining face transferred to the side of the open-pit slope. Additionally, large displacement and stress concentration were observed on the slope near the stoping line, which caused the slope body to move along the uppermost part of the slope first, and thereafter along the lower part. Various techniques for slope stability control are discussed, including the optimization of spatial and temporal relationships between open-pit and underground mining, the optimization of mining plans, and the use of monitoring and early warning systems. The results can provide a guide for slope stability control of similar open-pit mines in the process of mining coal resources.

Stability Control of Slopes in Open-Pit Mines and Resilience Methods for Disaster Prevention in Urban Areas: A Case Study of Fushun West Open Pit Mine

During the century-long mining process of the Fushun west open pit, slope slippage and deformation caused varying degrees of horizontal deformation, uneven settlement, and ground cracks on the surface of the urban areas, which caused a certain degree of damage to buildings and infrastructure and affected the livings of residents in the surrounding communities. In this study, a set of building reinforcement and community resilience enhancement methods that can resist slope deformation was proposed to improve the ability of urban areas to cope with slope geological hazards and emergency response. The main research contents included: Firstly, this paper systematically analyzed the deformation mechanism of the dip sloping and the inverse dip sloping section of the open pit mine, which was based on the field measured data and simulation calculation results. In other words, the horizontal deformation of the stratum in the dip sloping section was dominant, while the stratum in the inverse dip sloping section was prone to ground cracks and uneven settlement. In view of this, three surface deformation characteristic subdivisions of the surrounding urban area were proposed. In addition, a study on the damage characteristics of buildings with different types of foundations and structures under the influence of side slope deformation were carried out, and the anti-deformation reinforcement measures for load-bearing members mainly based on steel fiber concrete, carbon fiber materials and profile steel were proposed. Finally, a three-level disaster emergency setting system for urban areas around open pit mine was established, and the disaster prevention and resilience enhancement strategy for build and unbuilt the communities around the side slopes was constructed. The study aims to provide technical support to the overall resilience and response of the urban communities adjacent to open-pit mine slopes against consequent geological hazards and emergencies, thereby promoting sustainable urban development.

Monitoring and operational control of the gas hydrates formation in gas degassing pipelines

Purpose. Creation of operational determination methodology of mechanical and liquid deposit zones in deformed sections of mine degassing gas pipelines to prevent the process of hydrate formation and increase their throughput. Research methodology. The peculiarities of monitoring the technical condition of mine degassing systems (MDS), as well as a methodical support for operational control of their formation zones in the mine environment real conditions, are considered. Approaches to assessment, control and forecasting methods of gas hydrate formation zones under the influence of mine environment specific factors were determined and innovative technical solutions were developed to increase the degassing system throughput. Findings. Based on the results of modern trends assessment in the field of monitoring and forecasting gas hydrate formation zones, it was established that a fundamentally new approach to ensuring the accident-free operation of pipeline transport is being implemented in foreign practice. Originality. Grounded innovative technical solutions for existing degassing systems modernization to increase the throughput capacity of mine pipelines and predict the formation zones of crystalline gas hydrates during transporting methane-air mixture from wells to vacuum pumping stations. Practical implications. A program and methodology for monitoring and diagnosing mine degassing gas pipelines have been developed using innovative technical solutions to promptly determine the gas hydrate formation places and increase throughput during the current operation.

Provocative Eloquence: Theater, Violence, and Antislavery Speech in the Antebellum United States

Provocative Eloquence: Theater, Violence, and Antislavery Speech in the Antebellum United States