矿业科学学报

Reflections on resource utilization and sustainable development of closed coal mining areas

Wang Jiachen, Jürgen Kretschmann, Li Yang

2021, 6(6): 633-641. doi: 10.19606/j.cnki.jmst.2021.06.001

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Abstract:
With the adjustment of China's energy structure, decentralized coal mining has been transformed into refined, centralized and precise mining, which greatly reduces the number of coal mines in China.And a large number of coal mines with exhausted resources and backward production capacity are facing closure or abandonment.This transformation will confront China, at present and for a long time in the future, with a "post-mining" era similar to that in Germany.From the development trend of the transformation of China's energy structure and the macro strategy of coal resource development, there is no possibility to re-develop those coal mines that have been closed or will be closed.The closed mines not only cause environmental problems such as water and air pollution, but also social and economic problems such as difficulty in relocating employees and disposing fixed assets.Therefore, in view of the problems after the mining area is closed or abandoned, the treatment plans for post mining and the sustainable development strategy of resources in post mining industrial zone in Germany are referenced in this paper.Compared with the treatment schemes of closed mining areas in China, the concept that the utilization of resources after the closure of mining areas should be included in the top-level design of the whole mine development, and the idea of comprehensive utilization of coal underground space, mine water and other resources are proposed.Although various forms of abandoned mine utilization schemes have been put forward at home and abroad, the overall utilization rate is not high.It is still necessary to further explore the basic theories and methods of resource utilization in closed mining areas, as well as the corresponding education and technical personnel training measures to meet the development of these areas.

Traceability analysis of dustfall mercury and topsoil mercury in Wuda Coalfield

Li Shan, Li Chunhui, Liang Handong, Cao Qingyi, Gao Xiulong

2021, 6(6): 642-650. doi: 10.19606/j.cnki.jmst.2021.06.002

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Abstract:
The Hg isotopic ratios of coal, dustfall and topsoil from coal fire area No.9 in Wuda coalfield were determined by multiple-collector inductively coupled plasma-mass spectrometry(MC-ICPMS)to explore the possible coal seam source of surface Hg in coal fire areas.The findings were that the δ²⁰²Hg of coal, dustfall and topsoil were -1.98 ‰, -1.30 ‰ and -1.26 ‰, respectively, which showed a significant mass-dependent fractionation(MDF)characteristics.And there were slightly negative anomaly mass-independent fractionation(MIF)values of surface soil, such as dustfall(Δ¹⁹⁹Hg、Δ²⁰¹Hg: -0.13 ‰、-0.11 ‰)and topsoil(Δ¹⁹⁹Hg、Δ²⁰¹Hg: -0.11 ‰、-0.10 ‰).A comparative analysis of the characteristics of Hg isotopic showed that the values of surface soil(δ²⁰⁰Hg、δ²⁰²Hg、Δ²⁰⁰Hg)were all between the No.9 coal seam and the No.10 seam, and closer to the former, which indicated that the Hg source of surface soil in coalfire area No.9 was coal seam No.9 rather than No.10.The δ²⁰²Hg of dustfall was more negative than that of coal seam No.9, which was caused not only by the kinetic fractionation effect of burning and heating process but also by the geologic chromatography effect of migration process in crack and hold.Surface sample Hg isotopes characterizations can be used to distinguish coal seam Hg and then identify the burning coal seam.

Analysis and evaluation of essential factors for rock burst mechanism

Ma Nianjie, Zhang Wenlong, Li Jun, Lian Xiaoyong, Ren Jianjü

2021, 6(6): 651-658. doi: 10.19606/j.cnki.jmst.2021.06.003

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Abstract:
This paper puts forward the energy characteristics and mechanism elements of rock burst, and preliminarily establishes the evaluation index and system of roadway rock burst mechanism ("3 + 4" index system).The main criterion layer of the system is the energy release characteristic index of rock burst and the key element index of rock burst mechanism.The secondary criterion layer is sudden energy release, instantaneous energy release, concentrate energy release, and forming element, key element, hypothesis condition and universal regularity.The weight of each criterion layer is calculated by analytic hierarchy process method.The calculation method and classification standard of comprehensive evaluation results are put forward.According to the established evaluation index system of rock burst mechanism, the butterfly rock burst mechanism is evaluated, and the evaluation result is "excellent". The research results can be used to evaluate the existing rock burst mechanism, and point out the direction for the follow-up research of rock burst mechanism.

Status quo, opportunities and challenges of integrated application of coal-to-hydrogen and CCUS technology in China

Xu Mao, Zhang Xian, Fan Jingli, Gao Lin, Xu Dong

2021, 6(6): 659-666. doi: 10.19606/j.cnki.jmst.2021.06.004

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Abstract:
Against the background of addressing global climate change, hydrogen has attracted much attention because of its characteristics of being clean, carbon-free and efficient.In view of China's resource endowment, hydrogen demand and emission reduction demand, the integrated application of coal-to-hydrogen and carbon capture, utilization and storage(CCUS)technology is of great significance to China's low-carbon energy transformation.The development status, opportunities and challenges of integrated application of coal-to-hydrogen and CCUS technology in China were analyzed systematically in this study to provide relevant suggestions for the development of coal-to-hydrogen with low-carbon emission in China.The results showed that: ①Compared with other hydrogen production technologies, coal-to-hydrogen with CCUS has significant cost advantages; ②Compared with hydrogen production from renewable energy, carbon footprint is the weakness of coal-to-hydrogen, even though CCUS technology can reduce carbon emissions by about 90 %; ③Xinjiang, Shanxi, Shaanxi and Inner Mongolia can be the first areas to deploy coal-to-hydrogen with CCUS technology; ④The challenges of coal-to-hydrogen with CCUS mainly include lack of public recognition and the competition with renewable energy.In the future, China should strengthen the top-level design and publicity of coal-to-hydrogen with CCUS technology, actively promote the research, development and demonstration of coal-to-hydrogen with CCUS, so as to ensure the development of China's hydrogen industry.

Site selection of pumped storage power station in abandoned mines: Results from fuzzy-based multi criteria decision model

Wang Bing, Liu Pengshuai, Deng Kailei

2021, 6(6): 667-677. doi: 10.19606/j.cnki.jmst.2021.06.005

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Abstract:
The construction of Pumped storage power station entails large investment, strict requirements on environment, society, economy and safety, thus its site selection is highly influenced by numerous factors.Abandoned mines have natural elevation difference and space resources, which could save cost and shorten construction period for project modification of abandoned mines into pumped storage power stations.Based on the threshold theory, this paper puts forward the preliminary screening model for the location of abandoned mine pumped storage power station, comprehensively evaluates and optimizes the selected mines by using the coupling model of expert opinion and triangular fuzzy TOPSIS decision-making, and puts forward the multi-stage decision-making process and method system for the location of optimal pumped storage power station in combination with the requirements of sustainable development and resource reuse.The results show that the key indicators of site selection decision are mine water volume, water head, the distance from power grid, underground space, earthquake frequency, underground surrounding rock support stability and local power consumption.The natural conditions of the mine itself play a decisive role in the transformation of the pumped storage power station.Amony the alternative, Shigejie Coal Mine is the most suitable mine for the site of the pumped storage power station.

Automatic optimization design and application of drilling parameters for gas drainage in cross cut coal uncovering

Xie Beijing, Zhong Shiqing, Cao Xiao

2021, 6(6): 678-687. doi: 10.19606/j.cnki.jmst.2021.06.006

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Abstract:
Before uncovering coal in crosscut of high gas or outburst mine, it is necessary to design drainage boreholes and display the position of boreholes on the interaction surface of roadway and coal seam.In order to solve the problem that common AutoCAD and other drawing softwares can not efficiently meet the needs of a large number of calculations, combined with the relevant provisions of coal mine gas drainage and based on Matlab software programming, utilized Hungarian algorithm and simulated annealing algorithm, the automatic optimization design software of drilling parameters of crosscut uncovering coal gas drainage is developed.The results show that: ①the automatic optimization design software can be used to solve the problems of automatic optimization design and scheme comparison of drilling parameters based on any coal seam, roadway spatial position and extraction input conditions, which greatly improves the calculational efficiency and accuracy; ②The image drawing function realized by programming can realize the three-dimensional display of drilling track; ③On the basis of drilling parameters, the parameters of drilling layout are designed and verified synchronously to realize the closed-loop control of design and verification; ④The function of arbitrary hole filling parameters greatly improves the practicability of the automatic optimization design software and solves the problem of hole filling parameter design.The application of automatic optimization design of gas drainage borehole parameters in crosscut uncovering can obtain the optimal drainage borehole parameters, greatly improve the work efficiency of field technicians in coal mine, and provide important support for intelligent mining in coal mines.

Research on evolution characteristics of fault sliding displacement in slicing mining

Wang Hongwei, Wang Gang, Shi Ruiming, Zhang Xiaohai

2021, 6(6): 688-695. doi: 10.19606/j.cnki.jmst.2021.06.007

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Abstract:
Based on the geological structure of Yima coalfield and working face 21221of Qianqiu Mine as the engineering background, this paper designs a similar simulation experiment of fault slip instability under the influence of mining, and explores the characteristics of the influence of coal slicing mining disturbance on fault slip instability law.The results show that because the upper layer of the coal seam has caused a large degree of loosening and separation of the roof, when the lower layer of the coal is mined, the original loose roof rock further collapses, so the lower layer of the coal is mined Disturbance triggers a larger collapse range of the overlying rock mass, which makes the displacement changes around the fault become more intense, and the phenomenon of upper and lower disk displacement is more obvious.The strain energy peak accumulated in the coal rock mass is larger; at the same time, the fault slip is relatively lagging behind the violent release of strain energy in the rock mass of the coal, so the"sudden drop"phenomenon of the peak strain energy can be used as a precursor to judge fault slip and instability; the violent release of energy in the lower layer mining is earlier than the upper layer mining, and it is easier to induce the occurrence of rock-burst disasters.

Research on deep hole pre-splitting loosening blasting technology of hard roof cutting seam charge pack

Yin Zhongchang, Song Junsheng, Hu Shaoyin, Gao Quanchen

2021, 6(6): 696-702. doi: 10.19606/j.cnki.jmst.2021.06.008

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Abstract:
This research studies the key control technology in the process of hard roof loosening blasting, with Zhangji Mine of Huainan, Anhui as the background of the field test, combined with numerical simulation.Numerical simulation of the deep hole loosening blasting of the slitting charge was carried out.The field comparison test of the ordinary charge control blasting and the slitting charge was conducted.The results show that the proposed combined technology of loosening pre-splitting of ultra-deep holes in the huge and hard roof and directional fracture of the slitting charge can increase the directional expansion range of blasting cracks and solve the problem of excessively large bottom hole spacing in ultra-deep hole loosening pre-splitting blasthole blasting and so as to achieve precise control of the blasting fracture surface and the collapse position of the hard roof; artificially regulate the interval of periodic weighting, so that the hard roof can collapse in time and safely, and the working face can mine continuously and safely.

Study on key parameters of water bag dust removal in open air deep hole blasting

Guo Yao, Liu Dianshu

2021, 6(6): 703-710. doi: 10.19606/j.cnki.jmst.2021.06.009

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Abstract:
In this paper, the principle of water bag dust removal is studied by using ANSYS Fluent numerical software combined with field experiment.The influence of the detonation time difference and the distance between the water bag and the dust removal effect is analyzed emphatically.The results show that when the time difference between the first row of water bag initiation and the deep hole blasting is within the range of 1~1.5 s, the blasting water mist concentration is larger and the diffusion range is the widest, enabling the blasting water mist to fully contact with the dust cloud diffused over.When the detonation time between the first row and the second row of water bags is 0.5~1.0 s, the dust removal effect along the water bags is better.When the distance between the two water bags is 10~15 m, the coverage area of blasting atomization is larger, and the ability to capture dust after blasting is better.The field experiment results show that the dust fall at 50m increases by 27 %, the dust fall at 100 m increases by 12 %, and the dust fall at 150m decreases by 16 %.The effect of water mist and dust particles accelerates the settling of dust particles, and the dust fall in the near area increases, while the dust fall in the distance decreases.The dust concentration of the 50s after explosion is reduced by 36 % after the adoption of water mist dust capture measures.

Feature extraction and classification method of coal gangue acoustic signal during top coal caving

Yuan Yuan, Wang Jiawen, Zhu Desheng, Wang Jiachen, Wang Tonghai, Yang Kehu

2021, 6(6): 711-720. doi: 10.19606/j.cnki.jmst.2021.06.010

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Abstract:
To achieve the intelligent recognition of coal gangue in fully mechanized caving face, a coal caving acoustic signal collection device is designed, which can sense the movement of the tail beam and automatically trigger data collection.Field data is collected at the fully mechanized caving face 3106 of Gucheng Coal Mine, Shandong Energy, and it is manually labeled to construct a sample library of acoustic signal classification for top coal caving.Then, six machine learning classification methods are applied in the time domain, frequency domain and time-frequency domain, and the classification effect of them are evaluated by different frame lengths and different feature vector dimensions.The results show that: the classification effect based on time-frequency domain features is the most stable, and its accuracy rate is the highest by different frame lengths.The classification accuracy rate of random forest, K-nearest neighbor, decision tree and multi-layer perceptron model is above 80 %.Among them, the classifier performance based on wavelet packet decomposition and random forests are the best, and the classification accuracy is 93.06 %.There is a correlation between the time-frequency domain feature vectors and higher dimensions.Through dimensionality reduction, a small number of comprehensive features can be extracted and the amount of system calculations can be reduced.The principal component analysis is used to reduce the time-frequency domain feature vector to 20.Thus, the classification accuracy rate is further improved to 94.51 %.

Accuracy verification methods and experimental study of ground-based real aperture radar

Zhang Hao, Yang Xiaolin, Yang Feng, Zhang Batu, Yu Zhengxing, Ma Haitao

2021, 6(6): 721-729. doi: 10.19606/j.cnki.jmst.2021.06.011

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Abstract:
Conventional deformation monitoring means are limited by data accuracy, monitoring range, applicable environment and other factors, which seriously restrict the early warning and forecasting of landslide and collapse disasters.The microwave remote sensing method based on differential interference technology is an advanced technology for high precision monitoring of small displacements on non-contact surfaces nowadays.The self-researched ground-based real aperture radar system was applied in the research.This paper, based on the analysis of the signal model, summarized the process of target echo data processing with strong scattering characteristics and proposed a method applicable to verify the deformation monitoring accuracy of this type of radar system.Point target stationary and displacement experiments based on triangular plate angle reflector were carried out accordingly.Through the radar echo amplitude analysis and point cloud data fitting, the pre-defined target space position was discriminated and the target displacement standard value was determined, which proved the effectiveness of the method and the 0.1mm monitoring accuracy of the system.A slope monitoring experiment was carried out in Heidaigou open-pit coal mine in Inner Mongolia which combined with some point target deformation data illustrated the good practicality of the system.

A method of coal gangue detection based on deep learning

Zhao Xuejun, Li Jian

2021, 6(6): 730-736. doi: 10.19606/j.cnki.jmst.2021.06.012

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Abstract:
In view of the requirement to separate gangue from coal in coal preparation factory and avoid complex artificial feature design process based on computer vision in the past, an end-to-end gangue detection method by deep learning based on YOLOv3 is proposed.In order to reduce the size and speed up the operation of YOLOv3, depth-wise separable convolution and transpose convolution are used to improve the backbone network of YOLOv3.In order to improve feature integration from different levels, the spatial pyramid pooling layer is added to the model.For the purpose of accelerating convergence and accurately locating objects in the model, balanced L1 loss and distance-IoU loss are introduced.The results show that the proposed algorithm can accurately detect the gangue from the mixture of coal and gangue in real time, which provides an effective guarantee for improving the quality of coal and sorting efficiency.

Study on compatibility of fresh cement paste mixed with modified coal gasification slag and superplasticizer

Zhang Ming, Fang Kuizhen, Wang Dongmin, Yao Guang, Liu Ze, Li Huiquan

2021, 6(6): 737-745. doi: 10.19606/j.cnki.jmst.2021.06.013

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Abstract:
Coal gasification slag is a kind of solid coal chemical waste which mainly contains aluminosilicate minerals.The gasification slag modified by mechanical grinding and chemical excitation can be used as active admixture of composite Portland cement, which can effectively reduce the carbon footprint in the production and preparation of cement building materials.In order to clarify the working performance of modified gasification slag cement fresh paste, the compatibility of gasification slag-cement binary system with superplasticizer was evaluated by studying the fluidity, ζ-potential and particle size distribution of gasification slag-cement composite paste.The results show that the coal gas slag modified by diethyl alcohol monoisopropanolamine is a kind of mesoporous material, and it has good workability when the content is not more than 30 %.Polycarboxylic acid superplasticizer is beneficial to the dispersibility and fluidity of modified gas slag cement paste, and the fresh coal gas slag cement paste mixed with polycarboxylic acid superplasticizer shows modified Bingham fluid characteristics.The experimental results have high theoretical reference value for studying the workability of gas slag-cement binary system and its compatibility with superplasticizer.

Preparation of coffee residual based biochar and its removal of fluoride ions from mine water

Hou Pin, Li Jiaxing, Zhang Chunhui, Ran Yahui, Wu Mengmeng, Xiao Nan

2021, 6(6): 746-754. doi: 10.19606/j.cnki.jmst.2021.06.014

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In recent years, the problem of excessive fluoride in mine water is particularly prominent, which not only affects the water quality of reuse after treatment, but also endangers human health.Therefore, the study herein developed a novel adsorbent for fluoride -coffee residual based biochar(CRB)by applying the waste coffee residue as raw material and chemical activation, to realize the purpose of solid waste resource utilization and fluoride removal from mine water at the same time.The authors firstly optimized the preparation protocols of CRB through single factor, including the type of activator, activator concentration and activation temperature; then evaluated the adsorption efficiency of fluoride for CRB before and after optimization by kinetic and isothermal adsorption experiments; finally investigated the adsorption mechanism of fluoride for CRB after optimization(O-CRB)by surface physicochemical characterization.The results showed that the more favorable CRB for fluoride was prepared at the ZnCl₂ concentration of 4 mol/L and the activation temperature of 400 ℃.The maximum adsorption capacity of O-CRB for fluoride was 2.20 mg/g, which was 1.30 times higher than that of CRB before activation.In addition, compared with CRB, O-CRB exhibited higher amount of mesopore volume and specific surface area, as well as more oxygen containing functional groups(-COOH)and surface Zeta potential.Thus, the amount of chloride on the O-CRB surface decreased obviously(3.27 % to 0.61 %)after fluoride adsorption, whereas the amount of fluoride increased significantly(0.76 % to 10.34 %).This suggested that the adsorption of fluoride for O-CRB was mainly attributed to the electrostatic adsorption and ion exchange.

Catalytic synthesis of anisole over LDHs with different Mg/Al ratios

Zhang Haiyong, Zhang Lu, Liu Zhipan, Liu Siqi, Cui Yuhong

2021, 6(6): 755-763. doi: 10.19606/j.cnki.jmst.2021.06.015

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Abstract:
A series of layered hydroxides(LDHs)with different Mg/Al ratios were synthesized by coprecipitation method.MgAl LDHs and their calcined products were characterized by XRD, SEM, FT-IR, NH₃-TPD, CO₂- TPD, TG and ICP-OES, and were used to catalyze the vapor phase synthesis of anisole from phenol and dimethyl carbonate(DMC).The results show that MgAl LDHs synthesized by coprecipitation method have good hydrotalcite like structure when Mg/Al ratio is 2 to 4, mainly in the form of spherical lamellar aggregates.The interlayer spacing, average pore size and alkali acid ratio increase gradually when Mg/Al ratio is from 2 to 4.It is found that the selectivity of anisole first increases and then decreases with the acid-base ratio of the catalyst.The highest anisole selectivity of 88.93 % is achieved when the Mg/Al ratio is 4 and the acid/base ratio is 0.32.In addition, the effect of reaction temperature and mass space velocity on the catalytic performance are also investigated.

Evaluation and coupling coordination analysis of high quality development of China's coal industry: Empirical research based on data from 2000 to 2019

Yang Yuexiang, Wang Kunya, Ren Lei

2021, 6(6): 764-776. doi: 10.19606/j.cnki.jmst.2021.06.016

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Abstract:
This paper constructs an evaluation index system for high-quality development of coal industry from six dimensions: economic benefits, innovative development, intensive development, safe development, green development and efficient development.The high-quality development of China's coal industry from 2000 to 2019 is measured and analyzed in depth by entropy method, TOPSIS method and coupling coordination model.The results show that the high-quality development of the coal industry has achieved significant achievement, but the industrial scale is obviously out of sync with the high-quality development level.The main motivation and "short board" of high-quality development of the coal industry is significantly different in different stages of development.The six dimensions of high-quality development of the coal industry have been improved to varying degrees during the research period, but the speed of green development and high-efficiency development is relatively low.The coupling and coordination degree of the six-dimensional development of the coal industry has steadily increased, but has not yet entered the stage of "high-quality coordinated development"and the level of coordinated development needs to be improved.

2021 Vol. 6, No. 6