矿业科学学报

Review on the purification mechanism of mine water by coal mine underground reservoir

Jiang Binbin, Li Jingfeng, Wu Min, Su Chen, Bao Yixiang, Xue Rui

2023, 8(2): 137-145. doi: 10.19606/j.cnki.jmst.2023.02.001

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Abstract:
The purification effect of coal mine groundwater reservoir on mine water mainly lies in the water-rock coupling between the rock mass and mine water.This paper systematically reviews the research methods of water-rock coupling in coal mine underground reservoirs, and presents the characterization methods of water quality and physicochemical properties of rock samples.It employs static simulation, dynamic leaching, cycle purification simulation and other tests to explore the purification regulation of mine water in coal mine underground reservoir, uses numerical simulation to obtain the selective adsorption trend of ions in the reaction process, and combines Piper three-line diagram, Gibbs model and correlation analysis to reveal the mechanism of water-rock coupling.The purification effect and research progress of suspended solids, specific ions and organic matter in coal mine underground reservoirs are discussed.The paper shows that underground reservoir of coal mine has a certain purification effect on mine water, and the purification effect of specific ions is mainly related to filtration and adsorption.Three research directions of coal mine underground reservoir purification technology in the future are proposed: ①developing large-scale and low-cost treatment technologies for underground mine water based on water-rock coupling purification, ②developing a "three-in-one" water quality control technology for coal mine underground reservoirs coupled with multiple water treatment technologies, and ③exploring the underground storage and resource utilization technology of concentrated salt wastewater for the future studies of water-rock coupling.

Quantitative discrimination of seismic attributes of small faults in southern typical coalfield

Dai Shixin, Hu Pan, Dong Yanjiao, Xing Zhenhan, Li Xiang, Yang Fu

2023, 8(2): 146-155. doi: 10.19606/j.cnki.jmst.2023.02.002

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Abstract:
Faults are an important factor inducing mine safety accidents, and it poses difficulties on the identification of faults within 5 m of drop.Taking the Liupanshui coalfield of Guizhou province as the study area, this paper investigated the coalfield strata and carried out an on-site survey.It proposed a seismic physical model and used the unique velocity ratio of 1∶1.74 to realize the construction and analysis of small faults with a burial depth of 800 m, 1 000 m and 1 200 m and a drop of 5 m, 3 m and 1 m.This paper extracted a variety of seismic properties by seismic dynamics method to analyze small faults, and obtained the sensitivity of seven seismic properties to the characteristic response of small faults, including amplitude envelope, amplitude first derivative, and amplitude second derivative, and the correlation between seismic properties and drop was established accordingly.The results show that when the small fault drop of the coal seam is less than or equal to 5 m, there is a linear relationship with the traditional amplitude attributes, and a linear relationship with the seismic properties related to phase and frequency.There is high correlation between the amplitude envelope and the amplitude imaginary part, and low correlation between the instantaneous frequency, the amplitude first derivative, the cosine instantaneous phase, the amplitude second derivative and the amplitude envelope.

Prediction of surrounding rock stability of coal roadway based on machine learning and its application

Ma Xinmin, Chen Pan, Chen Chen, Feng Wenyu, Zhu Peixiao, Wang Yi

2023, 8(2): 156-165. doi: 10.19606/j.cnki.jmst.2023.02.003

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Abstract:
The classification of surrounding rock stability of coal roadway has important theoretical and practical significance for the design, construction and management of on-site rock mass engineering.This paper selected seven key indexes that affect the surrounding rock stability of coal roadway, collected the samples through field cases collection, questionnaires and literature measurement, and established the surrounding rock stability classification database.By drawing on six machine learning methods, this study established the classification prediction models of surrounding rock stability of coal roadway accordingly.Through model calculation, it is concluded that the Neural Network and the improved Support Vector Machine model have higher prediction accuracy.The model is applied to the actual project of Huozhou mining area.Results show that the neural network and the improved support vector machine methods have high prediction accuracy and good reliability.

Top-coal initial caving law of continuous group caving method in extra-thick coal seams

Wang Zuguang, Wang Shen, He Ziang, Li Huamin

2023, 8(2): 166-179. doi: 10.19606/j.cnki.jmst.2023.02.004

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Abstract:
In order to clarify the law of top coal caving with continuous group caving method in extra-thick coal seams, this study investigated the influences of the caving openings width on the morphological characteristics of caving body, the evolution law of the boundary of top coal and their spatial relationship based on the discrete element numerical simulation test and theoretical analysis.The results show that when the top coal thickness is 12 m, the increase of the ratio of coal caving height to caving width (δ) would cause the increase in the eccentricity of caving body.The eccentricity of caving body tends to have a steady value when the δ value increases to a certain value.In group coal caving, the increase of caving openings width would lead to higher single caving weight and caving efficiency with increasing influence range of the boundary of top coal increases and decreasing boundary slope.The length and height of tangent section between the initial boundary of top coal and the adjacent caving body increases continuously, which benefit top-coal recovery amount.The tangency between the top-coal caving body and the boundary of top coal of the previous adjacent caving group can be used as an effective method to evaluate continuous group caving.

3D experimental investigation of multi-port caving technology in LTCC with extra-thick seams

Li Meng, Wei Weijie, Zhang Xin

2023, 8(2): 180-189. doi: 10.19606/j.cnki.jmst.2023.02.005

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Abstract:
This paper investigated the multi-port caving technology to improve the top coal recovery and caving efficiency of the longwall top coal caving(LTCC)in extra-thick seams.The 3D drawing experiments are designed based on the actual geological conditions of Panel 8222 in the Tashan Coal Mine.Results indicated that in the initial drawing stage, the drawing body of single-port caving is roughly in the shape of a funnel with a narrow bottom and a wide upper part.The drawing body of multi-port coal caving is characterized by a wide middle and narrow ends, the coal caving volume shows single-port>double-port>three-port.During the initial drawing stage, the larger the number of openings, the greater the slope of the top coal boundary line; the larger the disturbance range to the top coal; and the higher the lowest point of the top coal boundary line, the more low-level top coal is lost.The lowest point of the top coal boundary is basically at the center of the group of supports.When the advance of the panel is completed, the three caving ports release more medium and low-level top coal above and in front of the supports, the coal caving volume generally shows three ports>double ports>single port.

Dynamic characteristics and constitutive model of coal samples with different length diameter ratio

Xie Beijing, Luan Zheng, Chen Dongxin, Zhong Shiqing

2023, 8(2): 190-201. doi: 10.19606/j.cnki.jmst.2023.02.006

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Abstract:
In order to study the dynamic performance of coal samples with different length diameter ratio under impact load, this paper used an improved Hopkinson compression bar experimental device (ϕ75 mm), and carried out the impact compression experiments under 6 impact grades (4.18~8.03 m/s)and 4 aspect ratios(0.33~1.33).It analyzed the correlation between the dynamic parameters and the aspect ratio in combination with the gray correlation theory, and this study then established a 4-parameter uniaxial strength type statistical damage model of coal and rock based on the mechanical mechanism, Weibull distribution and D-P failure criterion.Results show that: ① The length diameter ratio of coal samples has a quadratic function relationship with the strain rate and dynamic compressive strength; The relationship between the dissipation energy and the aspect ratio is a quadratic function, and the dissipation energy decreases with the increase of the aspect ratio; The relationship between the electromagnetic energy and the aspect ratio is a linear function and keeps a positive correlation. ② According to the grey correlation theory, this study obtained the influence order of length diameter ratio of coal sample on dynamic parameters: electromagnetic energy(0.88)>dynamic compressive strength(0.84)>dissipation energy(0.81)>strain rate(0.78).③ The initial constitutive model is constructed based on Weibull distribution and D-P criterion, and the dynamic compressive strength σ_max and strain rate、the relationship between length to diameter ratio n was corrected, and then the experimental stress-strain curves were compared to verify the reliability of the model(R²>0.91).

Flotation condition recognition based on multi-scale convolutional neural network and LBP algorithm

Jiang Xiaoping, Liu Junwei, Wang Lele, Lei Zhenbin, Hu Mingzhen

2023, 8(2): 202-212. doi: 10.19606/j.cnki.jmst.2023.02.007

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Abstract:
Aiming at the problems of difficult detection, low recognition efficiency and strong subjectivity of foam flotation dosing state, a flotation condition recognition method of nuclear random-weight neural networks(K-RVFLNs)combining multi-scale CNN characteristics and improved local binary patterns(LBP)calculation methods is proposed.Firstly, non-downsampling Shearlet multi-scale decomposition(NSST)is performed on the bubble flotation image, the original image is decomposed into different frequency scales, and a multi-channel CNN network is designed to extract features from the multi-scale image.By improving the LBP algorithm to extract features as a supplement, the image features extracted by CNN are fused with LBP features; Finally, the classification decision is made by mapping to a higher dimensional space by the nuclear stochastic right neural network, and the accurate identification of flotation dosing state is realized.Experimental results show that the method of multi-scale CNN and LBP-TOP feature fusion is 5.34 % higher than that of the traditional LBP algorithm, 3.76 % higher than that of single CNN feature recognition method, and the accuracy of flotation condition classification is as high as 96.38 % in combination with K-RVFLNs, and the recognition accuracy and stability are greatly improved compared with the existing methods, and this method reduces manual intervention and is conducive to improving production efficiency.

Reaction behaviors and synergistic effects for co-pyrolysis of Huadian oil shale and waste tire

Chang Zhibing, Wang Chuchu, Wang Yining, Wang Xinhong, Kuang Wenhao, Chu Mo

2023, 8(2): 213-221. doi: 10.19606/j.cnki.jmst.2023.02.008

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Abstract:
In order to improve the efficiency of oil shale pyrolysis and the utilization value of semi-coke, this paper co-pyrolyzed Huadian oil shale and waste tire.The weight loss behavior, product yield and composition properties of co-pyrolysis were investigated by thermogravimetric analyzer and aluminum retort reactor.The synergistic effect was analyzed based on the difference between experimental and calculated values.The results show that co-pyrolysis can promote the release of volatile matter, the actual weight loss is higher than the calculated value at 500 ℃, and reaches the maximum value of 2.86 % when the proportion of waste tire is 80 %.The mixed pyrolysis of oil shale and waste tire has the effect of "increasing oil and reducing water".When the waste tire accounts for 50 %, the actual oil yield is 32.91 %, which is 1.5 % higher than the calculated value, and the actual water yield is 1.20 % to 1.77 % lower than the calculated value.Meanwhile, the content of heavy components with boiling point higher than 350 ℃ in the pyrolysis oil increases.There is higher yield of C₁~C₄ hydrocarbons from waste tire pyrolysis, and the calorific value of semi-coke is up to 30.43 MJ/kg.Co-pyrolysis can also improve the calorific value of pyrolysis gas and semi-coke.

The causal mechanism of gas-coal cross-mining accidents

Guo Runsheng, Yu Xiaozhong, Wang Wen

2023, 8(2): 222-231. doi: 10.19606/j.cnki.jmst.2023.02.009

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Abstract:
The problem of overlapping mineral rights of coal and gas is common in the Ordos Basin of China.The interaction will occur when coal and gas are mined simultaneously, so it is necessary to solve the synergistic mining problem to eliminate the accident potential.Considering that there are many constraints in the simultaneous exploitation of gas and coal, this paper proposed an energy control failure model by energy abnormal release and STAMP.This model explains the applicability of information transfer cycle and the energy control failure model.Then, through the analysis of gas-coal mining process, this paper established the interaction between the energy unit, barrier unit, and disaster-bearing body, and analyzed the characteristics of energy transfer and safety barrier interaction.Finally, by analyzing 9 kinds of accidental release scenarios, this study proposed the identification behavior methods and control measures to prevent gas-coal cross-mining accidents.

Numerical analysis and research on coal pyrolysis characteristics in BGL gasification process

Zhang Lihe, Xu Deping, Xu Zhengang, Wang Yonggang

2023, 8(2): 232-241. doi: 10.19606/j.cnki.jmst.2023.02.010

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Abstract:
Research on the patterns of the internal temperature change and volatile analysis on the law of coal particle pyrolysis are essential to optimizing the furnace structure and operating parameters, while further improves the economy of BGL coal gasification.Based on the analysis of BGL coal gasification pyrolysis process, this study established the coal particle pyrolysis model.The decoupling algorithm was sadopted in solving the model, in which the heat transfer model adopted the chasing method, the pyrolysis kinetic model adopted the fourth-order single-step push-up method, and the ambient temperature was calculated by the moving bed one-dimensional model.The rationality of the model was verified by experimental data in literature.The simulation results show that the final pyrolysis temperature of BGL coal gasification is higher, and the temperature gradient inside the particles changes greatly.The particle size is 10 mm, the calculated final pyrolysis temperature is 1 372 K, and the calculated peak temperature difference between the surface and center of coal particles is 338 K. Taking the particle size of 40 mm, the corresponding calculated values are 1 412 K and 381 K respectively; The process of coal particle volatilization is similar to that of gas-solid non-catalytic condensation reaction, which proves that the coal pyrolysis process is controlled by heat transfer process.Pyrolysis kinetics is described by FZ general pyrolysis model, which has better adaptability than distributed activation energy model.When the moving bed one-dimensional model predicts the height of BGL coal gasification pyrolysis layer, the pyrolysis evaporation model is superior to FZ general pyrolysis model.The predicted height of pyrolysis layer is 0.616 5 m, which is consistent with the operation of agitator.

Research on the conceptual model and technical architecture of data governance for intelligent coal mine

Tan Zhanglu, Wang Meijun

2023, 8(2): 242-255. doi: 10.19606/j.cnki.jmst.2023.02.011

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Abstract:
There have been prominent contradictions between the limited network, storage, and computing resources of intelligent coal mines and the practical needs of technical collaboration, data collaboration, business collaboration, organizational collaboration and strategic collaboration, which makes data governance a key bottleneck in the construction of intelligent coal mines.However, there is not yet a complete conceptual model and technical architecture of data governance for intelligent coal mine.In response to this problem, this paper firstly defines data governance for intelligent coal mine and its key activities, clarifies the significance of data governance to the construction of intelligent coal mines, and builds a conceptual model of data governance for intelligent coal mine based on the five-element integration theory.Secondly, by drawing on the conceptual model, this study proposed the basic idea of data governance technology framework for intelligent coal mine, designed the data governance technology framework for intelligent coal mine and discussed the implementation strategy of data governance for intelligent coal mine.This may provide analytic framework and research method for data governance for intelligent coal mine, while shed tight on the theory and applicatiou of the data governance for intelligent coal mine.

Definition and evaluation of behavior safety state of coal mine workers based on combination weighting

Li Xiaoran, Chen Xin

2023, 8(2): 256-264. doi: 10.19606/j.cnki.jmst.2023.02.012

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Abstract:
In order to reduce the occurrence of safety production accidents in coal mine industry, this paper combined the definition of safety behavior and unsafe behavior, behavior safety theory and MMEM system theory to put forward the standard definition of safety state of coal mine workers' behavior.According to the behavior influencing factors, this study established the coal mine workers behavior safety state evaluation index system, including 4 first-level indicators 21 secondary indexes.The Improved-AHP method, Entropy Weight method and variance coefficient method were adopted to determine the subjective and objective weights and weight combination.Taking one mine as example for analysis, this paper chose extension comprehensive evaluation method to construct the evaluation model. Results show that: For the coal mine industry, the defined-evaluation-improvement(D-E-I)model is universal.The empirical evaluation level is Ⅳ or "relatively safe".The evaluation results are in line with reality, and the model is scientific and practical.

Scenario analysis of emergency management: macroscopic review and microscopic deconstruction

Nan Rui, Xiao Yejing, Wang Jing

2023, 8(2): 265-276. doi: 10.19606/j.cnki.jmst.2023.02.013

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Abstract:
Under the background of risk society, the foreseeable and unforeseeable risk factors significantly increase, which puts forward higher requirements for the modernization of China's emergency management system and capability.Scenario analysis is an analytical method and practical tool to study the uncertain future.Emergency management highly relies on scenario analysis for investigating uncertain factors.Taking the situation analysis of emergency management as the research object, this paper put forward a knowledge graph by CiteSpace to examine the trend and law of the research.Specifically, it probed into the contents and hot spots of micro-deconstruction scenario analysis from theoretical revision and expansion, process adjustment and specification, method application and practice.The research shows that the scenario analysis of emergency management has not formed a clear research paradigm, but it has great potential; the research content is diversified, but the localization research is relatively deficient; Current research can not meet practical needs, and the high complexity of major emergencies invites scenario analysis research.

The states of mental health of university students majored in mining and interventions based on courses

Liu Haijuan, He Ziming, Chen Panpan

2023, 8(2): 277-282. doi: 10.19606/j.cnki.jmst.2023.02.014

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Abstract:
The SCL-90 was applied to the students from China University of Mining and Technology Beijing with entry year between 2016 to 2019 to exam their mental health status, and the survey result had been compared and analyzed with the Chinese undergraduate norm.Results: from the overall mental health perspective, students majoring in mining showed a certain kind of mental health problems, but no significant differences comparing with the national undergraduates status; As for the types of mental health problem encountered, the students majoring in mining were observed with issues such as obsessive symptoms, sensitive interpersonal relationship, paranoid, depression and psychotic symptoms etc.Based on the above mentioned mental health problems, we have developed on strengthening the construction of courses, improving the students mental health status through multiple approaches.

2023 Vol. 8, No. 2