Mining Stage Research Articles

Stress Distribution and Optimum Spacing Determination of Double-Withdrawal-Channel Surrounding Rocks: A Case Study of Chinese Coal Mine

In this study, the 31113 fully mechanised working face in the Lijiahao Coal Mine was selected as the project background. The failure characteristics and optimum spacing of a double-withdrawal-channel surrounding rock were extensively investigated through field measurements, theoretical analysis, and numerical simulations. The following results were obtained. The loading influence range of the working face was fixed. Under the influence of mining, the stress distribution variation in the double-withdrawal channels with spacing and the influence of stress distribution on the surrounding rock stability of the withdrawal channels were determined. The optimum distance between the double-withdrawal channels to achieve the stability of the surrounding rock was at least 25 m, and engineering measures are required to limit the mining height in the final mining stage. The rationality of the main and auxiliary withdrawal channel spacing of 25 m and measures to limit the mining height in the final stage were demonstrated. The findings of this study provide a valuable reference for constructing the layout of withdrawal channels in the adjacent working faces of the same mining area.

Local versions realizing the pastoral model of metal production in conditions of the steppe ecosystems in the Urals-Mygodzhary region in the Late Bronze Age

Based on the results of the landscape-archeological studies in the Urals-Mugodzhary region and historical-ethnographic data, the problem of variability to realize the pasturable model metal production in the Late Bronze Age is discussed in the paper. The economic-cultural system is characterized by a harmonious combination of mobile livestock based on pastures and water sources’ seasonal rotation and separate technological stages of mining and metallurgical production. It was maximally adapted to the local steppe ecosystems’ peculiarities and promoted to save their dynamic balance due to rational use of natural-resource potential.

Effect of Face Length in Initial Mining Stage of Fully Mechanized Top-Coal Caving Face with Large Mining Height

Based on the field measurement of the end resistance of the support during the initial weighting of the basic roof and the macroscopic mine pressure behavior during the weighting period of 101, 22,211, 103 and 301 fully mechanized caving face in Changchun Xing Coal Mine, the mine pressure law of the working face is summarized and compared. Furthermore, the relationship between the working face length, the working resistance of the support (the weighting strength) and the macroscopic mine pressure behavior is obtained. In the range of face length 126–230 m, with the increase of face length, the end-of-cycle resistance of the support gradually increases, the dynamic load coefficient of the support gradually increases, and the strata behavior of the working face changes from strong to very strong. When the face length is short (126–140.5 m), the hanging roof area is too large to cause hurricanes when the working face is pressed, which threatens and damages the personal safety and equipment of the working face staff. Based on the above research, the problem of optimizing the surface length is proposed, and the surface length is determined to be within the range of 140–230 m.

PENERAPAN DATA MINING TERHADAP DATA COVID-19 MENGGUNAKAN ALGORITMA KLASIFIKASI

Coronavirus 2019 or more commonly referred to as COVID-19 is a type of virus that attacks the respiratory system. Until now the number of spread and the number of deaths caused by this virus continues to increase. As of April 21, 2020, based on data from the WHO, the total number of cases infected with this virus reached 2,397,217 with 162 deaths from all over the world. For South Korea itself, as of March 21, 2020, the total number of infected cases was 10,683 with a total of 237 deaths. In this study, researchers conducted data processing on the spread of COVID-19 in South Korea with Rapidminer using a classification algorithm, namely Naïve Bayes, C4.5, and K-Nearest Neighbor by performing the stages of selection, preprocessing, transfotmating, data mining and interpretation or evaluating the quality of the best accuracy of 80.79% with AUC of 0.881 achieved by the Naïve Bayes algorithm. The distribution of the data found that the influential attribute of the isolated class factor from the patient contained in the sex attribute where more women experienced isolation. Keywords— COVID-19, data mining, classification, C4.5, Naïve Bayes, K-NN

Study on Broken Floor Rock Mass by Mining Underground Pressure

As the dangerous level of floor water inrush in Chinese coal field is becoming more and more serious annually, the widely used formulas of broken floor rock mass are belonged to nonlinear type or empirical type. However, they are not well conformed to the practical situation and including mining underground pressure. The biggest depth of broken floor rock mass and the length of gob-floor or mining-floor until the maximum broken floor location are expressed by theoretical formulas on integrity theory. Taking a mining face in Chinese Anhui Province as the object, the relationship between broken floor rock mass and mining underground pressure is studied by numerical simulation, the theoretical analysis, and the DC exploration. The peak and scope of broken floor rock mass will enlarge until reaching limit value with the increasingly advanced distance. The mining gob stress contour is saddle-shaped, and its growing speed is becoming slower, so the 180 m coal mining face has reached the sufficient mining stage. Wave velocity of broken floor rock mass from 0 m to 16 m is greatly decreased by the mining disturbance, and it is basically conformed to theoretical formula and practical situation. The results can be relatively better used in the pressure mining of the Ordovician limestone, because it can provide some safe guarantee for mining deep coal seam.

Numerical simulation of fluid-solid coupling of stress failure characteristics of floor in coal mining face

In order to explore the characteristics of floor stress failure in the mining face under the action of non-uniform water pressure, a fluid-solid coupling model of non-uniform water-bearing area was established. FLAC-3D simulation software was used to simulate and analyze the changes in the initial mining stage, the sudden stress increase stage, the stress slow increase stage, and the stable stress stage during the mining process of the working face, and the failure characteristics of the floor were analyzed. It reveals the reasons why water inrush accidents are likely to occur at the front of the working face, which has a certain significance for understanding the mechanism of water inrush from the floor.

Efficiency assessment of coal mine use and land restoration: Considering climate change and income differences

Coal burning is still the main source of power generation in many Asian countries and is also the biggest cause of climate change. This research thus employs meta dynamic two-stage SBM (slack-based measure) under the exogenous model to examine 24 provinces in China as the research object. The first stage evaluates the efficiency of coal mining, taking employment in the coal industry and fixed assets in the mining industry as inputs, the development of non-oil and gas mineral resources a desirable output, and land damage as undesirable output and link. The second stage assesses the efficiency of land recovery, using land recovery funding as the input and recovery area as the output, and considers the climate change effect. The contribution herein is to discuss the degree of land destruction and the efficiency of land recovery through the different economic environments of different provinces and to divide the two groups by GDP. We also introduce high and low temperature days as exogenous variables to highlight the impact of climate change factors and to expose efficiency issues that may be underestimated. The results are as follows. (1) The efficiency value of the coal mining stage is higher than that of the land recovery stage, showing that China still pays more attention to economic benefits and ignores environmental responsibility issues. (2) More than 90% of China's provinces have coal mining expertise, but 70% of the provinces have low land recovery performance. (3) Eight provinces did not follow the Atmospheric Pollution Prevention Action Plan (APCP), the efficiency of coal mining deteriorated after the implementation of the policy. (4) Before the implementation of the APCP, land recovery in high GDP provinces was less efficient than in low GDP provinces. (5) Activating the APCP policy does not help technology upgrade. (6) The APCP policy caused the provinces to misevaluate their investments in fixed assets and misdirected their decisions on land recovery funding. However, the efficiency of land recovery after the implement of APCP was better. (7) Neglecting climatic factors causes serious errors in coal mine efficiency.

Comprehensive analysis control effect of faults on the height of fractured water-conducting zone in longwall mining

In order to examine the height of a fractured water-conducting zone due to the presence of a fault, a typical working face in the Baodian Coal Mine which is located in the Yanzhou Coalfield of northeastern China is examined as a case study. Two subsurface conditions with and without a fault are considered. In this study, equations are developed to calculate the maximum span of the unsupported roof with and without the presence of a fault. Numerical models are used to examine the changes in stresses and the development of a plastic zone at different stages of mining. A comparison of the results based on theoretical analysis and numerical model shows that the height of the fractured water-conducting zone increases significantly with the presence of a fault. The height of the fractured water-conducting zone is about 1.50 times higher than the case without a fault. The results provide important insight into the prevention and control of water inrush in mines with thick and loose deposits and a thin bedrock.

Study on the mechanism of a new fully mechanical mining method for extremely thick coal seam

In order to achieve safe and efficient mining for extremely thick coal seam more than 20 m, a new fully mechanized top-coal caving mining method with first extracting the middle layer was proposed in this study. In this study, physical model with a similarity ratio of 60:1 and the corresponding numerical simulation were performed to explore the laws of fracture propagation, displacement and stress fields of top-coal. The results show that the top-coal fragmentation effect of this new mining method is better than that of slice caving mining, especially on the period of the secondary top-coal caving stage. During the stage of pressure-relief mining (stage Ⅰ), the top-coal collapse shape can be observed as approximately trapezoidal. Meanwhile, there is periodic behaviours for the broken and instability of the top-coal cantilever beam structure on the top of support along with the decrease of top-coal displacement. During the secondary stage of fully mechanized top-coal caving mining (stage Ⅱ), the origin cantilever beam structure of top-coal can be fully broken with loose structure. And the total displacement of the medium layer of top-coal is greater than that of the upper layer, while the vertical crack can be obviously observed in the lower layer of top-coal. In addition, the higher fractal dimension of top-coal fracture contributes on the broken of top-coal. The evolution characteristics of displacement and stress fields of top-coal and overlying strata in physical model are verified through numerical simulation.

Surface runoff from an area undergoing soil rehabilitation after bauxite mining in southeastern Brazil

AbstractChanging hydrological processes and soil characteristics are of major environmental concern in surface mining. Runoff may be the best factor for determining the efficiency of rehabilitation after this type of mining, and needs more in‐depth studies, but the environmental factors require more attention in order to control that runoff. The objective of this study was to compare the runoff during post‐mining rehabilitation after the extraction of bauxite with that before mining, and to identify the factors that most affect it. Runoff from before the mining operations and during the rehabilitation after those operations were collected in seven plots in the area of a bauxite mine in southeastern Minas Gerais State, Brazil. The physical‐environmental and anthropic factors interfering with the runoff were characterized for both periods, and their results were submitted to principal component analysis to define the parameters, which most demand attention in the mining rehabilitation stage. This study provides the first records of runoff in the field in areas rehabilitated after surface mining in Brazil, where the runoff decreased (1.75‐times or 42.79%) from 0.76 to 0.30% of the precipitation during rehabilitation, compared to the reference area. The total porosity, density, and resistance of the soil, associated with the maintenance of slope, surface roughness, and vegetation cover, are the factors demanding more attention during the rehabilitation stage of surface mining in order to minimize runoff.

Rendering mine closure governable and constraints to inclusive development in the Andean region

Although the early stages of mining are often associated with promises of socioeconomic development based on economic growth, limited oversight of mine closure practices has tended to deliver lingering social, economic, and environmental problems across the Andean region. New and revised legislation, policies, and regulations that address mine closure in the region demonstrate what I argue are attempts to render mine closure governable—that is, the circumscribing of mine closure as an ‘intelligible’ and strictly technical problem, amenable to state intervention, without challenging existing bureaucratic processes or political economic structures. Such narrow framings of mine closure exclude possibilities for local consultation and participation, and, by extension, hinder the relationship between mine closure and a more socioeconomically inclusive and less environmentally damaging form of post-mine development. I outline discrete attempts to make mine closure more easily governable in the Andean region, with detailed focus on the cases of Colombia and Chile, and show that this process also tends to render local populations invisible. I point to the conspicuous disconnect between high hopes for mining's contribution to Andean states' economic growth and concrete possibilities for post-mine development based on ideas of equity, inclusion, and social justice. I conclude by pointing to the need for legal and regulatory institutions in the Andean region that more actively facilitate the creation and distribution of benefits, services, and livelihood opportunities following mine closure.

RETRACTED ARTICLE: Big Data Mining and Analysis Based on Convolutional Fuzzy Neural Network

The purpose of this paper is to solve the shortcomings of traditional big data mining and analysis (BDMA); this paper compares and analyzes the denoise effect of wavelet transform and wavelet packet analysis and chooses to use wavelet packet analysis method to denoise the signal and extract fault feature vector. Finally, the extracted feature vectors are divided into two libraries, including training and testing. The fuzzy convolutional neural network (FCNN) is trained by using the training sample database data, the network weights are constantly modified, and the projection of nonlinear is computed between the input features and output features. After the expected recognition accuracy is achieved, the performance of FCNN is evaluated by using the detection samples. The performance comparison and analysis are conducted with the traditional BDMA algorithm, mainly including the comparison of recognition accuracy and learning convergence speed. Two stages of feature extraction and data mining (DM) are constructed on the big data set. The experimental results prove the effectiveness of wavelet transform feature and FCNN in analyzing and mining in big data. Finally, through the example of BDMA, this paper verifies that the organic combination of wavelet transform feature extraction and FCNN algorithm obviously improves the efficiency, meets the requirements of big data analysis, and provides potential application value for BDMA.

Innovative Concept of Production Support System for the LW Bogdanka Mine

The research work results, presented in the article, describe a system concerning the management of a production line in the aspect of stabilization and improvement of the run-of-mine quality and maximization of economic effects. Basing on the geological deposit model, the authors concentrated on designing mining operations and on planning production parameters. Special attention was paid to a development of the mine workings design module, the mining operations scheduling module, the module for mixing and optimization from the quality point of view as well as the module for mining operations revenues and forecasts of costs. Forecasting the production quality, planning and integration of mining processes with coal preparation processes and sales are discussed in detail. The article is ended with some recommendations of general character, including quality management at the stage of mining and production planning, quality monitoring at the stage of coal mining, and its preparation. The system is oriented onto production quality forecasting and onto an integration of mining, preparation and sales planning.

Monitoring and Analysis of Ground Deformation in Mining Area Based on SBAS Technology

In view of the serious harm and significant economic loss caused by large-scale surface subsidence in Huangling Mining area. Firstly, the surface deformation information was obtained by using the Small Baseline technology during 2007-2009 (ALOS-1) and 2018-2019 (Sentinel-1A), and then the deformation position and magnitude changes were compared in these two different periods, finally, the time series analysis of the surface subsidence funnel in the mining area was performed. The results showed that: (1) The average annual deformation rate respectively reached 360 mm/a and 480 mm/a during 2007-2009 and 2018-2019. It was found that compared with 2007-2009, the deformation position moved up in 2018-2019, and the deformation area and magnitude increased. Combined with the analysis of the mining area data, the Huangling mining area was in the early stage of mining from 2007 to 2009. As the advance of mining working face and the passage of time, the deformation position would move up in 2018-2019. (2) From 2018 to 2019, the most serious surface subsidence in the Huangling mining area was located in the northwest of Shuanglong Town, including Huangling No. 2 Coal Mine. The maximum cumulative subsidence reached 300mm. The results of the study indicated that the main cause of subsidence in this area was underground coal mining. The analysis of the deformation law provides a decision basis for the subsequent rational mining and treatment of the mining area.

Assessing of Losses and Dilution Impact on the Cost Chain: Case Study of Gold Ore Deposits

The conditions of declining gold grade in the ore, increasing depth of excavation, and de-creasing unallocated stock of deposits make it necessary to develop efficient solutions for the mine-to-mill process, which have to be adapted to each specific mining plant and will optimizes production costs. Current research focuses on a case study that demonstrates how indicators of mining losses and dilution influence the variation of costs chain in the production cycle. The article examines the topical issue of determining the effects at the mine-to-mill stages due to changes in losses and dilution. The author’s approach to the formation of a mine-to-mill cost chain is proposed by integrating several cost estimation methods into the general cost estimation methodology. The estimation methodology is a compilation of factor analysis and cost engineering methods that take into account the change in costs due to the variation of losses and dilution. It was proven that with variations in losses and dilution, cost savings arise due to changes in the volume of work on ore averaging, ore transportation, and beneficiation. For the case of the Kuranakh ore field, there are no effects at the mining stage. The use of internal reserves by means of managing ore quality parameters allows reducing the costs per ton of processed rock mass along the entire production chain.

Perangkat Pembelajaran Usaha dan Energi Berbasis STEM Terintegrasi Kearifan Lokal Timba Laor di Desa Allang Kabupaten Maluku Tengah

21st-century learning should include STEM to grow interested in the Indonesian nation to love and master science, technology, engineering, and mathematics. They are included in it for physics learning. STEM is a practical learning approach because it combines knowledge, mathematics, technology, and techniques. This aim to make students as problem-solvers, inventors, have innovation, independent logical thinking, technological literacy, connect their culture and history with education, and apply their knowledge in real life. Thus, it is necessary to implement STEM-based learning integrated lokal wisdom /culture of the community in which the learners are located. One of the lokal wisdom of coastal communities in Maluku is Timba Laor. This research aims to develop a High School Physics Learning Tool business concept, and STEM-based Energy integrated lokal wisdom Timba Laor in the village of Allang Central Maluku district, a valid, practical, and effective Plomp model. The stages of mining carried out in this research activity are the development of high school physics learning tools business concept and STEM-based Energy integrated lokal wisdom Timba Laor in the village of Allang Central Maluku District. Test models by providing surveys of physics teachers to empirically validate the learning devices that have been compiled, analyzed, and revised. The resulting product is a learning device physics high school concept business, and energy-based STEM integrated lokal wisdom.
 
 
 
 Keywords
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 Business and Energy, Learning Tools, STEM, Timba Laor
 
 
 

A DOFS-Based Approach to Calculate the Height of Water-Flowing Fractured Zone in Overlying Strata under Mining

The distributed optical fiber sensing (DOFS) is a technique that can obtain full spatial and temporal information concerning the behavior of a large range of measurand fields along a fiber path and realize the distributed monitoring of the overburden section under mining. To calculate the height of water-flowing fractured zone caused by the exploitation of coal, this study employed distributed optical fiber sensors with OSI-C-S optical frequency domain reflectometry (OFDR) technology and designed a similar-material model test based on the engineering geological conditions of Daliuta Coal Mine. Through the test, deformation characteristics of overlying strata were studied, the linear relationship was summarized between the strain gradient and the shear stress measured by fiber sensors when the rock layer cracks, and a method was proposed of using the measured strain to measure the height of the water-flowing fractured zone in overlying strata. The test results show that there are several locations where the sign of the shear stress changes (positive to negative or vice versa) in the overlying strata during the initial stage of coal seam mining. As the working face advanced, the change locations gradually concentrated at the place where the rock cracks. By identifying the breakpoints of the rock and the locations where the sign of the shear stress measured by fiber sensors changes, this paper calculated the height of the water-flowing fractured zone in Daliuta Coal Mine. After comparing the height with the abscission layer position in the model test and the predicted height by the empirical formulas in the specification, it has been found that the three results are basically consistent, which in turn verifies the accuracy of this method.

Critical Conditions and Energy Transfer Characteristics of the Failure Process of Coal-Rock Combination Systems in Deep Mines

With the steady increase in the size, intensification, and modernization of coal production enterprises, the deep coal resources in large coal bases are gradually entering the mining stage. When the coal mining reaches the deep zone, the interactions between various underground dynamic hazards begin to occur. These interactions are affected by the engineering geological environment and can lead to the occurrence of severe compound hazards. When coal and gas outbursts occur and destabilize the mining area, the high geostress causes the multiphysical coupling effect of the laminated overburden system to become more pronounced. Therefore, we analyzed the development path of a coal-rock system under instability conditions from the perspective of coal–rock coupling, constructed a model of the coal-rock combination system’s structure, and proposed three directions (i.e., strain softening, limit equilibrium, and dynamic instability) for the development of coal-rock system instability. Then, we established a model for the critical conditions of the system’s failure process and elucidated that the release of the rock’s elastic energy promoted the instability of the coal. Furthermore, we verified the established critical conditions through laboratory tests on a coal-rock combination structure and obtained the patterns of the rock energy transferring into the coal seam during the instability failure process of the coal–rock combination structure. When the coal–rock combination structure failed, the rock strain reached its maximum value and the strain rebound phenomenon occurred. The stored elastic strain energy released by the rock into the combination system accounted for 26% to 53% of the accumulated energy in the rock itself, and the released elastic energy and the new surface area of the crushed coal sample followed a logarithmic relationship. The findings of this study provide theoretical support for the identification and quantitative analysis of instability due to the dynamic hazards of coal-rock gas in deep mines.

Investigation of the Optimization of Unloading Mining Scheme in Large Deep Deposit Based on Vague Set Theory and Its Application

With the development of shallow surface mineral resources in metal mines, it is gradually turning to the stage of deep mining. According to the current mining depth and the average annual depth, during the period of “14th Five-Year Plan,” one-third of the underground metal mines will reach or exceed the mining depth of 1,000 m, with the deepest being 2,000 m. In the stage of deep mining, mines will face the conditions of high stress, high temperature, high well depth, and strong mining disturbance, which will greatly increase the difficulty of large-scale deep mining. Among them, the high ground stress environment is the principal problem of many technical problems in deep mining. The selection of mining method has become a prerequisite for solving the problem of efficient and safe mining of deep deposits. In this paper, the vague set theory was introduced into the selection of mining methods and a vague set model for deep unloading mining schemes was established. Taking the Jinchuan No. 2 mining area as the engineering background, four unloading schemes for deep mining were proposed, and the Vague set model was used for optimization. It is concluded that the mining approach with large-section unloading is the optimal unloading mining plan. The application shows that it has the advantages of high unloading efficiency, large production capacity, and low loss index. It has been fully promoted in the deep mining of the mining area. It is feasible and effective to use the vague set theory in the selection of deep unloading mining schemes, which provides a proper approach in the selection of deep unloading mining schemes.

Sustainable Open Pit Mining and Technical Systems: Concept, Principles, and Indicators

Sustainability of the open pit mining and technical system (MTS) is one of its key goals in the changing conditions of the external and internal environment. All MTS’s subsystems must function in concert to achieve this goal. The structure of the MTS is formed by many subsystems and elements, which are evaluated by a significant number of indicators. A comprehensive assessment of the MTS for all possible indicators is a complex and time-consuming task. However, each subsystem and element of the MTS has a different effect on the sustainability of this system. The MTS’s parameters change significantly during transition periods, for example, at a new stage of open-pit mining or when switching to an open-underground method of developing mineral deposits. The MTS’s sustainability declines during the transition periods. Changes in the parameters of technological processes during these periods can have a negative impact on the state of the economic and social subsystems of mining enterprises, as well as on the environment. Ensuring the sustainability of an MTS during transition periods requires the development of new approaches and principles for managing the work of mining enterprises, based on the alignment of economic goals, with goals in the field of ecology and social development. The study substantiates the key role of one of the MTS subsystems—the opening-up of an opencast system (OOS). It is shown that this system has a decisive influence on sustainable functioning and development. The systematization of the principles of sustainable functioning and development of mining enterprises and its systems has been carried out. Four groups of principles are distinguished: system-wide principles of management, principles of development of mining enterprises, principles of MTS development, and principles of the MTS’s subsystem development. The proposed system of principles is based on the idea of a sequential transformation of the subsystems at all stages of design and operation. A feature of the proposal system of principles is the consideration of economic, social, and environmental aspects to ensure the specified parameters for the sustainable functioning and development of mining enterprises. The results of the analysis of the factors of the external and internal environment of the MTS are presented. The parameters and indicators for assessing the sustainability of OOS and MTSs were selected and substantiated. The justified parameters and indicators were ranked using the fuzzy Analytic Hierarchy Process (AHP). The results of the assessment showed a high convergence of expert opinions on a group of economic parameters, which were rather high in technical and technological parameters. However, there is a divergence of expert opinions on social and environmental parameters. As a result of the study, it was concluded that the current management decisions are aimed at ensuring the economic and technological sustainability of MTS functioning, while achieving the goals of sustainable development of this system is not ensured. The methodology developed and presented in the study can be used to assess the sustainability of the functioning and development of MTSs.