Mining Infrastructure Research Articles

Korelasi Point Load Index dan Uniaxial Compressive Strength pada Satuan Batupasir dan Batulempung Formasi Latih untuk Penentuan Koefisien Kekuatan Batuan di Pit X Tambang Batubara PT Berau Coal, Kalimantan Timur

Physical and mechanical properties of rock for engineering purposes are indispensable for any civil/construction, mining and other engineering requirment. The results of the uniaxial compressive strength (UCS) test are very much needed in various geotechnical analyzes or engineering, in particular in the mining industry in relation to the calculation of the pit slope design and other mining infrastructure. Rock samples used in this study were obtained from the results of geotechnical drilling (full core drilling). The rock engineering properties test to obtain UCS and PLI values was carried out in the laboratory. Testing the rock hardness index using the point load index (PLI) can be done more quickly, cheaply, practically and can use rock samples with a variety of sample shapes. The focus and object of the research are mudstone and sandstone units as part of the Lati Formation. These two types of layers are the most dominant rock types as a constituent of the pit slopes in the research area. To ensure that the correlation results are in accordance with the rules of scientific research, the distribution of UCS and PLI data from laboratory test results is verified using a statistical approach / testing. Correlation and analysis between the two rock engineering properties test results are very useful for geotechnical analysis data input. The coefficient or constant values obtained can be used to determine the rock strength values used in various geotechnical analyzes so that the analysis can be carried out more efficiently, effectively and quickly and can support geotechnical engineering work.

Experimental testing of novel hybrid rubberised concrete double skin tubular columns with filament wound CFRP tube under axial compressive loading

Rubberised concrete formed by using recycled scrap tyre chips as the substitution for natural aggregates, has recently emerged as an important research topic. Though it conserves the mineral aggregates, it is associated with reduced compressive strength. Different confinement techniques with fiber-reinforced polymer (FRP) wrapping and steel have been commonly used to restore the lost strength that also provided some other benefits such as enhanced ductility and energy dissipation capacity. In this paper, a novel hybrid double-skin tubular column termed as “Hybrid RuDSTC” consisting of rubberised concrete, filament wound circular CFRP tube, and cold-formed circular steel tube was developed and experimentally explored to evaluate its performance under axial load. The parameters of the experimental investigation were void ratio, slenderness ratio, and percentage rubber replacement. Results showed that the novel Hybrid RuDSTCs can provide a promising sustainable solution with greater strain capacity compared to their unconfined counterparts. Better strain and enhanced ductility of the hybrid RuDSTCs compared to non-rubberised hybrid DSTCs enable their use in seismic prone regions and mining infrastructure.

Extraction of Au(III) by Microbially Reduced Metal-Organic Frameworks.

Gold is a critical resource in the jewelry and electronics industries and is facing increased consumer demand. Accordingly, methods for its extraction from waste effluents and environmental water sources have been sought to supplement existing mining infrastructure. Redox-mediated treatments, such as Fe(II)-based platforms, offer promise for precipitating soluble Au(III). We hypothesized that microbial generation of Fe(II) in the presence of sorbent metal-organic frameworks could capitalize on the advantages of both biological- and chemical-driven extraction approaches. Toward this aim, we tested Au(III) removal by Shewanella oneidensis cultured with Fe(III)-based materials (ferrihydrite, Fe-BTC, MIL-100, or MIL-127). Across all tested materials, S. oneidensis generated the highest levels of redox-active Fe(II) (1.99 ± 0.27 mM) when cultured with MIL-127 as a respiratory substrate in a bicarbonate-buffered medium. This translated into superior Au(III) removal performance in terms of both removal rate and capacity (k = 2.55 ± 0.60 h-1; Q = 183 mg g-1). Unlike other materials tested, MIL-127 also maintained cell viability following repeated Au(III) challenges, enabling the regeneration of Fe(II) in the framework. Together, these effects facilitated the treatment of multiple cycles of Au(III) by S. oneidensis-reduced MIL-127. Overall, this work demonstrates that microbial generation of Fe(II) can facilitate the removal of Au(III), augmenting purely adsorptive platforms. Given the biological and chemical modularity of our system, our results suggest that future optimizations to microbial Fe(II) generation may offer promise for improving Au(III) extraction processes.

How to Assess the Moment Tensor Inversion Resolution for Mining Induced Seismicity: A Case Study for the Rudna Mine, Poland

Underground exploitation of georesources can be highly correlated with induced seismic activity. In order to reduce the risk and improve the mining operations safety, the mining activity is monitored by a dedicated seismic network. Moment tensor inversion is a powerful method to investigate the rupture process of earthquakes in mines, providing information on the geometry of the earthquake source and the moment release. Different approaches have been proposed to estimate the source mechanisms, with some advantages and limitations. One of the simplest and most used methods rely on the fit of the polarity and amplitude of first P wave onsets. More advanced techniques fit the full waveforms and their spectra. Here, we test and compare moment tensor and focal mechanism estimations for both inversion techniques. In order to assess the inversion resolution, we built realistic synthetic data, accounting for real seismic noise conditions and network geometry for the Rudna copper mine, SW Poland. The Rudna mine pertains to the Legnica-Glógow Copper District, where thousands of mining induced earthquakes are detected yearly, representing a serious hazard for miners and mining infrastructures. We simulate a range of different processes and locations, considering pure double couple, deviatoric and full moment tensors with different magnitudes and located in different mining panels. Results show that the P-wave first onset inversion is very sensitive to the geometry of the seismic network, which is limited by the existing underground infrastructure. On the other hand, the quality of the moment tensor solutions for the full waveform inversion is mainly determined by the strength of mining tremor and the signal-to-noize ratio. We discuss the performance of both inversion techniques and provide recommendations toward a reliable moment tensor analysis in mines.

Thermodynamic assessment of the novel concept of the energy storage system using compressed carbon dioxide, methanation and hydrogen generator

The main aim of this paper is to characterize the concept of a novel energy storage system, based on compressed CO2 storage installation, that uses an infrastructure of depleted coal mines to provide required volume of tanks, and, additionally, hydrogen generators, and a methanation installation to generate synthetic natural gas that can be used within the system or taken out of it, e.g., to a gas grid. A detailed mathematical model of the proposed solution was built using own codes and Aspen Plus software. Thermodynamic evaluation, aiming at determining parameters, composition and streams in all the most important nodes of the system for the nominal point and when changing a defined decision variable δ (in the range from 0.1 to 0.9) was made. The evaluation was made based on the storage efficiency, volume of the tanks and flows of energy within the system. The storage efficiency in the nominal point reached 45.08%, but was changing in the range from 35.06% (for δ = 0.1) to 63.93% (for δ = 0.9). For the nominal value of δ, equal to 0.5, volume of the low-pressure tank (LPT) was equal to 132,869 m3, while of the high pressure tank (HPT) to 1219 m3. When changing δ these volumes were changing from 101,900 m3 to 190,878 m3 (for LPT), and from 935 to 1751 m3 (for HPT), respectively. Detailed results are presented in the paper and indicate high storage potential of the proposed solution in regions with underground mine infrastructure.

Thermodynamic and economic assessment of compressed carbon dioxide energy storage systems using a post-mining underground infrastructure

The paper presents the results of thermodynamic and economic analysis of a compressed carbon dioxide energy storage system using low-pressure reservoir, where carbon dioxide cannot be stored at a high-pressure, like in standard concepts. Such limitations may occur in post-mining underground excavations, the availability of which will increase in the coming years due to the ongoingdecarbonisation of economies in many countries. In this paper the concepts of two systems using an isobaric high-pressure tank and a non-isobaric low-pressure reservoir which are built within a post-mine shaft are presented. The paper presents the results of technical analysis for systems with various structures. The results of the analysis show the storage potential and effectiveness of the compressed carbon dioxide energy storage system, which includes one, two or three sections of carbon dioxidecompressor together with thermal energy storage tanks and the same number of expander's sections. The analyses were carried out for various ranges of allowable pressure change in the low-pressure reservoir. The paper identifies the pros and cons of the systems, such as high values of energy storage efficiency (which may reach almost 80%) and their technical complexity. The storage capacity and the required tank volumes were also assessed. For the system with single-section compressor and single-section expander, more in-depth analyses were carried out. The analyses were carried out for the assumed geometry of the mine shaft. For this solution economic analysis were also carried out. For the decision variables considered, the Levelized Cost of Storage ranges from 314.6 to 439.4 €/MWh. The inspiration for the development of the system was the high storage potential of underground mine infrastructure available in the region of the Upper Silesia located in Poland; however, the solution is universal and may be applied in other industrial regions.

Mining as a temporary land use: A global stocktake of post-mining transitions and repurposing

Post-mining land use and associated economies have become a priority issue in mine lifecycle planning amongst many major companies. Ensuring the post-mining landscape is returned to a safe and stable condition is usually the first order priority in mine closure, though achieving this is often a challenge. The drive for industry to do more than rehabilitation is also growing. One of the many drivers for this expectation is the scale of mines, with many mining leases occupying thousands of hectares. Some of this land may be used for other purposes with relatively little intervention. For the mine footprint itself, it is often not possible or feasible to return the landscape to the prior condition, although creative repurposing of mine features and elements of mine infrastructure may be an option. At the same time, these large-scale mines employ hundreds, sometimes thousands of people and consideration of economic transitions for mining workforces, notably local dependant populations, is increasingly expected of industry post closure, as employment is often positioned at the “heart” of development. In this article, we reframe mining as a temporary land use. This approach positions post-mining land use as intrinsic to the mine lifecycle, including the planning and operational phases. We developed a global database of repurposing cases building on the S&P Global Market Intelligence database, relevant literature and other publicly available information. We provide an overview of the findings and the themes to emerge from this global repurposing database of 141 cases. Our findings include: our general observations on the research process; an analysis of the most common repurposing land uses; factors influencing repurposing, including factors internal and external to the company; initial observations about industry approaches to repurposing. Finally, we argue that reconceptualising mine ‘closure’ and the associated mining legacies is an essential operational shift the extractives industry, notably the major companies, will need to make to keep pace with societal and local community expectation.

The Intensity of Heat Exchange between Rock and Flowing Gas in Terms of Gas-Geodynamic Phenomena.

Gas-induced geodynamic phenomena can occur during underground mining operations if the porous structure of the rock is filled with gas at high pressure. In such cases, the original compact rock structure disintegrates into grains of small dimensions, which are then transported along the mine working space. Such geodynamic events, particularly outbursts of gas and rock, pose a danger both to the life of miners and to the functioning of the mine infrastructure. These incidents are rare in copper ore mining, but they have recently begun to occur, and have not yet been fully investigated. To ensure the safety of mining operations, it is necessary to determine parameters of the rock–gas system for which the energy of the gas will be smaller than the work required to disintegrate and transport the rock. Such a comparison is referred to as an energy balance and serves as a starting point for all engineering analyses. During mining operations, the equilibrium of the rock–gas system is disturbed, and the rapid destruction of the rock is initiated together with sudden decompression of the gas contained in its porous structure. The disintegrated rock is then transported along the mine working space in a stream of released gas. Estimation of the energy of the gas requires investigation of the type of thermodynamic transformation involved in the process. In this case, adiabatic transformation would mean that the gas, cooled in the course of decompression, remains at a temperature significantly lower than that of the surrounding rocks throughout the process. However, if we assume that the transformation is isothermal, then the cooled gas will heat up to the original temperature of the rock in a very short time (<1 s). Because the quantity of energy in the case of isothermal transformation is almost three times as high as in the adiabatic case, obtaining the correct energy balance for gas-induced geodynamic phenomena requires detailed analysis of this question. For this purpose, a unique experimental study was carried out to determine the time required for heat exchange in conditions of very rapid flows of gas around rock grains of different sizes. Numerical simulations reproducing the experiments were also designed. The results of the experiment and the simulation were in good agreement, indicating a very fast rate of heat exchange. Taking account of the parameters of the experiment, the thermodynamic transformation may be considered to be close to isothermal.

Innovative seismic imaging of volcanogenic massive sulfide deposits, Neves-Corvo, Portugal — Part 1: In-mine array

To evaluate and upscale the feasibility of using exploration tunnels in an operating mine for active-source seismic imaging, a seismic experiment was conducted at the Neves-Corvo mine, in southern Portugal. Four seismic profiles were deployed in exploration drifts approximately 650 m beneath the ground surface, above the world-class Lombador volcanogenic massive sulfide deposit. In addition to the tunnel profiles, two perpendicular surface seismic profiles were deployed above the exploration tunnels. The survey was possible due to a newly developed prototype global positioning system (GPS) time transmitter enabling accurate GPS synchronization of cabled and nodal seismic recorders, below and on the surface. Another innovative acquisition aspect was a 1.65 t broadband, linear synchronous motor (LSM) driven — electric seismic vibrator (e-vib) used as the seismic source along two of the exploration tunnels. We have evaluated the challenges and innovations necessary for active-source tunnel seismic acquisition, characterized by high levels of vibrational noise from the mining activities. In addition, we evaluated the LSM vibrator’s signal and overall seismic-data quality in this hard rock mining environment. Our processing results from the tunnel data and 3D reflection imaging of the Lombador deposit below the exploration tunnels were checked for consistency through constant-velocity 3D ray-tracing traveltime forward modeling. For imaging purposes, 3D Kirchhoff prestack depth and poststack time-migration algorithms were used, with both successfully imaging the targeted deposit. The results obtained show that active-source-seismic imaging using subsurface mining infrastructure of operational mines is possible. However, it requires innovative exploration strategies, a broadband seismic source, an accurate GPS-time system capable of transmitting GPS-time hundreds of meters below the surface, and careful processing. The results obtained open up possibilities for similar studies in different mining or tunneling projects.

Gamification Based Blockchain Tournaments Between Miners

We have modelled mining resource and cryptocurrency-related relationships into a non-cooperative game. Then we took advantage of the traffic congestion results, set a native convention for the Nash equilibria, and created a short algorithm to find the equilibria. Next, we will make calculations for several system models whose variations follow the existing mining resources and have appropriately allocated according to the details of the mining complexity level that has defeated. In the included resources, the game's result is the allocation of resources as a feature of a normalized Nash equilibrium. In the model that has proposed, we provide a property structure of the type of equilibrium that exists, such as a condition where there are two or more mining infrastructures that will be active and another state that explains that no Miners get results in wanting a specific cryptocurrency, like bitcoin.

Exploring Deep Learning for Dig-Limit Optimization in Open-Pit Mines

This paper explored a convolutional neural network to assess the clustering of selective mining units (SMUs), generated by a genetic algorithm (GA) approach. The purpose of the GA was to optimize a set of dig limits in a mine bench. Dig limits are boundaries to separate/split SMUs as per waste and other processing categorizations so they can be feasibly and profitably be extracted by existing mining infrastructure. This was achieved by involving the cluster design and the affiliated decision variables into existing mining optimization frameworks that enhance the process's efficiency and thereby increase profitability. However, the catch being that such computation comes costly both from a monetary and time consumption perceptive. This paper aimed to address this very cost issue and how to overcome this with the use of deep learning. Specifically applying the statistical learning algorithms to assess the cluster quality of the GA computed dig limit, as current assessment methodology consumes up to 70 percent of the total computation time. Short-term mine planning applications need to be directly usable by mine operators’ personnel and must be generated quickly to be useful in dynamic mining environments. This requirement shall save up time and cost. A case study was conducted on a bench with multiple destinations and 420 SMUs to test whether a convolutional neural network (CNN) can make predictions on clustering quality and discover the best CNN architecture for the task. The case study showed that using a CNN does ensure prediction accuracy and can speed up the time of computation time by 3900%.

Prediction of the Potential Daily Output of a Shearer-Loader

Economic analysis allows for determining the required daily output under certain natural and mining conditions based on the costs of the production process in a particular mine infrastructure. Therefore, there is a need to determine the potential daily output of a longwall using the technical equipment at the disposal of the mine. In the case of mines, when exploiting a few longwalls simultaneously in the conditions of bumping hazards, it is indispensable to ensure safety. Due to a necessity of keeping a safe distance among the longwall fronts, when planning their exploitation, developing a prediction of the longwalls in advance during the planning period is needed. To predict the daily production from a longwall and daily advance of the longwall in the analyzed period, it is necessary to know the current operating time of machines and the capacity of the shearer under given conditions. The current working time of machines results from the available time and the degree of its utilization, which is determined by the sum of unplanned breaks in the production process. The shearer productivity is determined by its haulage speed. Both factors mentioned above are random. Hence, a calculation module has been developed, whose task is to estimate the distribution parameters of these indicators based on empirical data. The algorithm for estimating the parameters of one of the distributions: normal, steady or gamma and its special case of the exponential distribution and Poisson for the obtained input empirical data, constituting a sample from the population, is proposed. The input data are a sequence of numbers obtained from the measurement of the current operating time of machines. These data can be obtained from the longwall shearer memory card, on which its operating parameters are recorded in each longwall. On this basis, it is possible to generate random values of both parameters for individual days of operation. The possibility of determining the haulage speed, based on the longwall shearer’s characteristics obtained from the computer simulation of the mining process, is also discussed. The simulation of the mining process is carried out using the GeneSiSv.3.1 software, developed for designing a picks layout on the drum. The characteristics of the shearer production potential also take into account the capacity of loading the cutting drum. It results from the presented characteristics that, when mining coal with a compressive strength of 27 MPa, the haulage speed is limited by the loading capacity of the cutting drum and, with greater cuttability, by the power of the electric motor driving the drum. The paper presents algorithms describing the procedure of generating random values necessary for determining the longwall production potential and the daily advance during the assumed period. The subject matter presented in the paper is part of a bigger project which concerns planning of a mine operation and developing a few longwalls in the conditions of bumping hazards.

Leverage as a Moderator of the Effect of Company Size, Managerial Ownership, and Conflict of Interest on Accounting Conservatism

This study aims to examine the influence of company size, managerial ownership, and conflict of interest to accounting conservatism with leverage as the moderating variable. The population was mining companies and infrastructure, utilities, and transportation companies which were listed on the Indonesia Stock Exchange (IDX) from 2015 to 2018, which are 118 companies. The sample was determined by purposive sampling which resulted in 12 companies with 36 units of analysis. The data were collected by using documentaries. The analysis techniques used descriptive and inferential with the help of IBM SPSS version 21. The results showed that managerial ownership had a negative influence and conflicts of interest had a positive influence to accounting conservatism, company size had not influenced to accounting conservatism, and leverage moderated the relationship of managerial ownership to accounting conservatism, but it was unable to moderate the relationship of company size and conflict of interest to accounting conservatism. The conclusion of this study is the low managerial ownership presses the existence of expropriation; therefore, it can increase the accounting conservatism. The high conflict of interest increases the application of accounting conservatism to reduce conflicts that occur. Meanwhile, leverage influences the company’s financial risk, therefore it is able to moderate the influence of managerial ownership to accounting conservatism.&#x0D; Keywords: Accounting Conservatism; Company Size; Conflict of Interest; Leverage; Managerial Ownership

Belt Conveyors Rollers Diagnostics Based on Acoustic Signal Collected Using Autonomous Legged Inspection Robot

Growing demand for raw materials forces mining companies to reach deeper deposits. Difficult environmental conditions, especially high temperature and the presence of toxic/explosives gases, as well as high seismic activity in deeply located areas, pose serious threats to humans. In such conditions, running an exploration strategy of machinery parks becomes a difficult challenge, especially from the point of view of technical facilities inspections performed by mining staff. Therefore, there is a growing need for new, reliable, and autonomous inspection solutions for mining infrastructure, which will limit the role of people in these areas. In this article, a method for detection of conveyor rollers failure based on an acoustic signal is described. The data were collected using an ANYmal autonomous legged robot inspecting conveyors operating at the Polish Ore Enrichment Plant of KGHM Polska Miedź S.A., a global producer of copper and silver. As a part of an experiment, about 100 m of operating belt conveyor were inspected. The sound-based fault detection in the plant conditions is not a trivial task, given a considerable level of sonic disturbance produced by a plurality of sources. Additionally, some disturbances partially coincide with the studied phenomenon. Therefore, a suitable filtering method was proposed. Developed diagnostic algorithms, as well as ANYmal robot inspection functionalities and resistance to underground conditions, are developed as a part of the “THING–subTerranean Haptic INvestiGator” project.

Segmentation and classification algorithms applied to sentinel-2A images for geological mapping: case of the Al Glo'a sheet (1/50000), Morocco

The multispectral image, of Landsat 7 and 8; Aster and Sentinel-2A, has good results in lithological, structural, hydrothermal and mineralogical alteration mapping. Segmentation and image classification are two complementary steps as they are allowed the most important operations in the field of image processing. In this sense, this work aims at evaluating the potential of segmentation and classification algorithms for the generation of surface geological maps, hydrothermal alterations and lineaments. Given the good resolution of the Sentinel 2A (10m), the three images, (11/12; 11/2; 11/8), 12.8.2, main component 1, 2 and 3 (11.12.2), processed by five algorithms (K-means, isodata, watershed, efficient graph-based image segmentation, thresholding) for geological mapping and then mining exploration. The study displayed that 1) Watershed algorithm can be used for topographic and hydraulic studies, it can be very useful in the preparation phase of geological and mining infrastructures; 2) threshold segmentation does not give good results in terms of geological discrimination since it divides each image into two parts; 3) the same thing for the effective thresholding and segmentation of graph-based images; 4) The Isodata and K-means algorithms show good geological discrimination.

Unraveling the Morphological Constraints on Roman Gold Mining Hydraulic Infrastructure in NW Spain. A UAV-Derived Photogrammetric and Multispectral Approach

The province of León preserves a unique hydraulic infrastructure 1200 km-long, used for the exploitation of auriferous deposits in Roman times. It represents the most extensive waterworks in Europe and is one of the best-preserved examples of mining heritage in Antiquity. In this work, three mining exploitation sectors (upper, middle, and lower) characterized by channels and leats developed in different geological materials were examined, using Unmanned Aerial Vehicles (UAVs). A multi-approach based on a comparison of photogrammetric and multispectral data improved the identification and description of the hydraulic network. Comparison with traditional orthoimages and LiDAR data suggests that UAV-derived multispectral images are of great interest in areas where these sets of data have low resolution or areas that are densely covered by vegetation. The results showed that the size of the channel box and its width were factors that do not depend exclusively on the available water resources, as previously suggested, but also on the geological and hydraulic conditioning factors that intervene in each sector. Additionally, the detailed study allowed the establishment of a water sheet maximum height that was much lower than previously thought. All in all, these inferences might help researchers develop new strategies for mapping the Roman mining infrastructure and establishing the importance of geological inheritance on the construction of the hydraulic system that led the Romans to the accomplishment of the largest mining infrastructure ever known in Europe.

Human–environment interactions at a short-lived Arctic mine and the long-term response of the local tundra vegetation

AbstractArctic mining has a bad reputation because the extractive industry is often responsible for a suite of environmental problems. Yet, few studies explore the gap between untouched tundra and messy megaproject from a historical perspective. Our paper focuses on Advent City as a case study of the emergence of coal mining in Svalbard (Norway) coupled with the onset of mining-related environmental change. After short but intensive human activity (1904–1908), the ecosystem had a century to respond, and we observe a lasting impact on the flora in particular. With interdisciplinary contributions from historical archaeology, archaeozoology, archaeobotany and botany, supplemented by stable isotope analysis, we examine 1) which human activities initially asserted pressure on the Arctic environment, 2) whether the miners at Advent City were “eco-conscious,” for example whether they showed concern for the environment and 3) how the local ecosystem reacted after mine closure and site abandonment. Among the remains of typical mining infrastructure, we prioritised localities that revealed the subtleties of long-term anthropogenic impact. Significant pressure resulted from landscape modifications, the import of non-native animals and plants, hunting and fowling, and the indiscriminate disposal of waste material. Where it was possible to identify individual inhabitants, these shared an economic attitude ofwaste not, want not, but they did not hold the environment in high regard. Ground clearances, animal dung and waste dumps continue to have an effect after a hundred years. The anthropogenic interference with the fell field led to habitat creation, especially for vascular plants. The vegetation cover and biodiversity were high, but we recorded no exotic or threatened plant species. Impacted localities generally showed a reduction of the natural patchiness of plant communities, and highly eutrophic conditions were unsuitable for liverworts and lichens. Supplementary isotopic analysis of animal bones added data to the marine reservoir offset in Svalbard underlining the far-reaching potential of our multi-proxy approach. We conclude that although damaging human–environment interactions formerly took place at Advent City, these were limited and primarily left the visual impact of the ruins. The fell field is such a dynamic area that the subtle anthropogenic effects on the local tundra may soon be lost. The fauna and flora may not recover to what they were before the miners arrived, but they will continue to respond to new post-industrial circumstances.

Seismic activity induced by exploitation in vicinity of mined-out space, case study from deep copper ore mine in Poland

Rock bursts are one of the most difficult to recognize and assess natural hazards in deep copper ore mines in Poland. The occurrence of rock bursts is conditioned by a number of complex geological and mining factors. The impact of each of the factors on the state of seismic hazard is sometimes impossible to be determined. The correct recognition of the rock mass condition and the causes of rock burst threat gives a chance for advance preparation of adequate prevention, and thus for eliminating or reducing the threat to the level of tolerated risk. In Poland’s copper ore mines, continuous observation of seismic activity is carried out, which is expressed in the number of tremors and their energy over a specified period of time. Moreover, the effectiveness of prevention measures and, in particular, of the active ones, which are aimed at provoking seismic energy emissions through properly executed winning blasting works, is calculated and analysed. Reducing the amount of energy accumulated in the rock mass reduces the risk of rock bursts. Exploitation is carried out in a way that avoids parallel approach of the operational front towards the goafs, drifts, and faults with drops greater than the height of the mined deposit. However, over forty years of mining of the copper ore deposit, which has created the large areas of mined-out space mean that mining works are increasingly carried out under restrained conditions. There are unfavourable geological and mining situations in the exploitation fields, disrupting rhythmic development and an even front line. The specific structure of the copper ore deposit in Poland makes it possible to conduct multidirectional cutting and to introduce local changes in the adopted directions of exploitation. Cases of operational fronts approaching goafs occur often in the vicinity of old mining infrastructure and when there is the need to mine remnant parts of the deposit not previously intended for exploitation or not mined yet. Generally, exploitation in the direction of goafs or yielding zones is limited to the cutting and yielding works. The purpose of the study was to analyse the seismic and rock burst hazard in an exploitation field located at a depth of 850 m in a copper ore mine, over a period of 5 years, when mining was carried out towards goafs. Seismic activity and the effectiveness of rock burst prevention measures were assessed and analysed. The active prevention i.e. the group winning blasting works was an inseparable element of the excavation technology. It was found that when the operational front progressed towards adjacent goafs, there were symptoms of an increase in rock mass pressure causing the destruction of roof rocks and, as a consequence, deterioration of roof stability, squeezing of floor, relaxation of the side walls and increase of seismic activity, which posed the potential threat of rock bursts.

Conflict and contestation in Kyrgyz mining infrastructure

Themes of mining, infrastructure and rural development present fertile grounds for contestation and conflict in Central Asia. In mineral-rich Kyrgyzstan, mining brings development, tax revenue and political disorder. The country's relatively robust civil society and ineffective government embolden critique and protest yet also make lasting resolution difficult. This is exacerbated in rural regions that host mines as limited opportunities and information has led to drastic action in pursuit of jobs, environmental protection and community benefit. Foreign investment, such as from China's Belt and Road Initiative (BRI), predominates in resource extraction. In this paper research at 3 mining sites in Kyrgyzstan is presented. Conflict includes violent protest and rock-throwing that closed a mine, concern over water contamination and environmental damage and arrest of citizens for community control. The cases identify the disconnect between mine ownership and licensing arrangements in the capital and practices and perceptions in rural communities. Framed by the government's need for tax revenue vs interests of local villages, the forces of conflict make negotiated settlement difficult and continued strife predictable. Until government perspectives, legal processes and company engagement shifts, contestation will be the defining tenet of mining infrastructure in Kyrgyzstan.

A methodology based on strain analysis for identifying potential discontinuous deformation zones in sublevel caving mines

Underground mining operations using the sublevel caving method often result in discontinuous ground deformations involving surface cracks. Determining the limit of the discontinuous deformation zone is important for the relocation of neighbouring residential areas, mining infrastructure, and the planning of underground mining operations. The limit of the discontinuous deformation zone is characterised by the outermost surface crack, which is a tensile crack when it occurs and is correlated with the horizontal ground tensile strain. In this study, a mathematical procedure combining the horizontal displacement, as periodically monitored by total station and GPS, multiquadric radial basis function (MQ-RBF) interpolation, and continuum mechanics is provided to calculate the strain state at any point on the ground. Then the relationship between a new tensile crack and horizontal ground tensile strain is studied to determine the criterion representing the presence of a new tensile crack. This means that, when the criterion at any point on the ground is satisfied, the point will have the potential to crack. Based on this, the potential discontinuous deformation zone where surface cracks may occur can be identified, potential break angles at representative sections can then be determined. A case study is presented to illustrate the results given by the above methodology. The result shows that when major principal horizontal ground strain ε1 at any point on the ground reaches the potential cracking major principal strain, PCMPS (6 mm/m in this case study), the point will have the potential to crack. Subsequently, the area within the outermost contour of the PCMPS can be defined as the potential discontinuous deformation zone. Moreover, the approximate matching of the limits of potential discontinuous deformation zones and surface cracks verifies the reliability of the mathematical procedure and the rationality of the PCMPS in identifying the discontinuous deformation zone. Additionally, in this case study, the potential break angles at two respective sections are significantly different, indicating that the break angles should be further studied and care taken in design of works in these two zones, respectively.