矿业科学学报

Development strategy of pumped storage in underground space of closed/abandoned mines

Yang Ke, Fu Qiang, Yuan Liang, Chen Ning, Liu Qinjie, Yang Qinggan

2023, 8(3): 283-292. doi: 10.19606/j.cnki.jmst.2023.03.001

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Abstract:
To achieve carbon peaking and carbon neutrality, China has deepened its energy revolution with the largest renewable energy power generation capacity in the world.In face of the unstable power supply of large-scale renewable energy, a new power system has been proposed and constantly upgraded, which promoted the construction and development of pumped storage power station.Under terrain constraints and the ecological red line, the site selection of traditional pumped storage power station is a hard nut to crack.At the same time, a large number of closed/abandoned mines and resource exhausted cities emerged in the process of coal capacity reduction.This study gave a detailed overview of the status quo of pumped storage power station in China, and analyzed the environmental benefits of the combination of closed/abandoned mines and pumped storage, such as water resource pressure relief and greenhouse gas emission reduction.Based on the different modes of closed/abandoned mine pumped storage power stations, this study analyzed the application potential of closed/abandoned mine pumped storage.Finally, this paper proposed the development strategy of China's abandoned mine pumped storage, and the prospects of closed/abandoned mine+energy storage in multiple industries.

Key grouting technology and engineering demonstration for green mines

Du Jinlong, Pan Shuren, Liu Changyou, Wei Yunxun, Lu Yan, Pan Haiyang, Qi Kuan, Zhao Ming, Liu Housong, Yao Hongxin, Zhou Yao, Yan Jia, Li Shinian, Zhang Biao, Zhang Sinuo

2023, 8(3): 293-307. doi: 10.19606/j.cnki.jmst.2023.03.002

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Abstract:
This study proposed the multi-coupling grouting system with the aim to tackle green mine problems such as surface collapse, water resources destruction and coal based solid waste accumulation.Successfully applied, this system yielded the following major achievements: this study (1) probed into the patterns of development and evolution in mining separation space and primary fracture space, and conducted the intelligent identification of grouting space by means of theoretical analysis, physical and numerical simulation and field detection.(2) prepared multi-source inorganic high-performance grouting materials for different scenarios by using coal-based solid wastes (coal gangue, fly ash), and developed a new KEP grouting material with underwater dispersion resistance, high volume coefficient and high plastic strength.(3) applied cluster well and feather well to grouting hole drilling and and developed an all-weather, high pump pressure and large flow intelligent grouting system; The reinforcement grouting technology is applied for the first time to strengthen the effect of grouting to reduce settlement.(4)put forward the technology system of grouting effect monitoring and detection, and emphatically expounded the borehole detection method of combining drilling core and well logging.(5)formed an intelligent technology system based on the methods of separation space grouting to reduce settlement and treat waste, caving zone grouting to treat waste, goaf grouting to strengthen foundation bearing capacity and treat waste, and roof fissure grouting to control water gushing as the core.Engineering demonstrations of this system have been carried out in Xiadian coal mine, Xinpu phosphate mine, Caojiatan coal mine, Gaojiabao coal mine and other places, which yielded good results.

Electromagnetic response characteristics of small coil device for mine transient electromagnetic method

Shi Zhihao, Cheng Jiulong, Xu Zhongzhong, Jiang Guoqing

2023, 8(3): 308-314. doi: 10.19606/j.cnki.jmst.2023.03.003

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Abstract:
The study of the transient electromagnetic detection device with small sized coil and easy installation underground will offer new insights into the real-time dynamic exploration and forecast water-bearing structure in excavation roadway.By drawing on the full-space transient electromagnetic theory, this paper adopted the three-dimensional time-domain finite element method for numerical simulation to explore the characteristics of the secondary field response obtained by small coil excitation and the transient electromagnetic response received by the magnetic core coil.This study constructed a geological-geophysical model of the water-bearing fault in front of the roadway excavation working face, studied the transient electromagnetic response characteristics of the small coil device for the water-bearing fault, and compared the effects of small coil and conventional coil in advance detection.The study shows that : ①the decay law of the induced electric potential generated by the small coil source excitation is the same as that of the induced electric potential generated by the conventional transmitting coil with time, ②the magnetic core coil can effectively improve the induced signal strength, ③the application of both the small coil device and the conventional coil device can effectively explain the distribution range of the low resistance area, ④the detection results match the verification results of the roadway excavation.Combined with the underground field test, this paper verified the applicability and effectiveness of the small coil device applied to mine transient electromagnetic method advance detection.

Occurrence characteristics and formation mechanism of coal-bearing kaolinite rocks in Datong coalfield

Liu Jianping, Liu Linsong, Liu Di, Zhang Shuai, Lei Haochen

2023, 8(3): 315-322. doi: 10.19606/j.cnki.jmst.2023.03.004

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The kaolinite rocks, a resource of industrial value, are abundant in the coal-bearing strata of the Datong coalfield.To look into the occurrence characteristics and formation mechanism of coal-bearing kaolinites, this paper uses the kaolinite deposits in the Taiyuan formation of the Late Paleozoic in the study area as the research object.The occurrence horizon, structural composition, rock type and genesis analysis of the kaolinite deposit were studied through field geological survey, microscopic identification, XRD analysis and geochemical analysis.Results show that the kaolinite rock in Datong coalfield is mainly located in five layers, including the No.9 coal floor, the No.8 coal floor, the No.3 and 5 coal floor, No.3 and 5 coal parting and the No.2 coal floor to No.3 coal roof.The kaolinite is the predominant mineral(the content is between 60 % and 90 %)associated with minor minerals like quartz, feldspar, mica, anatase, siderite and diaspore.The micro-components of the kaolinite rock in the study area were divided into grains, kaolinite crystals, mineral clasts and matrix.In addition, the kaolinite rock in the study area were categorized as grain kaolinite rock, cryptocrystalline kaolinite rock, lump kaolinite rock and sandy kaolinite rock according to the present morphology analysis.In conclusion, the genesis of kaolinite rock is mainly terrigenous transport sedimentary and volcanic ash.

Determination of chlorine in coal by Eschka's mixture decomposition-ion chromatography

Wen Zhenhai

2023, 8(3): 323-328. doi: 10.19606/j.cnki.jmst.2023.03.005

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Abstract:
This paper proposed a new method for the determination of chlorine in coal by Eschka's mixture decomposition-ion chromatography so as to satisfy the needs of determining chlorine content in coal samples in large batches in coal exploration, coal production and processing industries.Specifically, this paper improved the sample pretreatment steps and determined the experimental parameters.The detection limit of the method was 0.001 7 %, the relative standard deviations of ten parallel determinations of three actual coal samples were in the range of 1.08 % ~3.92 %, the recoveries of six spiked determinations were in the range of 98 % ~104 %, and the results of the three standard coal samples were all within the guaranteed values.Results showed that the detection limit of the method was lower than that of the national standard method, and the precision and accuracy met or exceeded the national standard method.The determination of chlorine in coal by Eschka's mixture decomposition-ion chromatography has the advantages of simple operation, low cost and high determination efficiency and could be widely applied in the batch determination of a large number of samples.

Mechanisms of hydration inhibition on the surface of montmorillonite in deep shale via molecular dynamic simulation

Li Dongbo, Li Guangzhou, Liu Qinlong, Lu Wei

2023, 8(3): 329-338. doi: 10.19606/j.cnki.jmst.2023.03.006

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Abstract:
Borehole instability is one of the most complicated technical problems in oil and gas exploration and development.The hydration and expansion of clay minerals is the critical factor causing wellbore instability in which the surface hydration is difficult to be removed due to the large hydration potential.In this light, through molecular dynamic simulation, this paper probed into the CaCl₂ inhibitory effect of concentrations, temperatures and pressures on the surface hydration of montmorillonite which revealed the macroscopic mechanism.Results indicated that inhibition of cations were achieved by binding water molecules on the surface of montmorillonite and decreasing the transport and conductivity of water molecules, thereby regulating the invasion of water molecules into the surface of montmorillonite.The ability of inorganic salts to inhibit surface hydration were CaCl₂>NaCl>MgCl₂>KCl.The study found that calcium ions easily adsorbed surface water molecules to form stable outer sphere complex.With the increase of CaCl₂ concentration, coordination number, hydration number and hydration radius of calcium ion decreased, and the inhibitory effect diminished.When the temperature increased and the pressure decreased, the conductivity and transport capacity of water molecules was enhanced in the system, the coordination number of calcium ion descended, and mechanical strength declined.

Combustion performance of sub-nanometer Pd/S-1 catalyst for ventilation air methane

Zhang Xueli, Zhu Tao, Yuan Bo, Li Chen, Wang Meidan, Zhang Baixuan

2023, 8(3): 339-347. doi: 10.19606/j.cnki.jmst.2023.03.007

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Coal mining leads to ventilation air methane emission, which not only pollutes the environment but also runs counter to "carbon neutral, carbon peaking" in China.This study prepared a sub-nanometer Pd cluster catalyst encapsulated in the Silicalite-1 molecular sieve support by the one-pot hydrothermal method, which has excellent catalytic activity and stability in methane catalytic oxidation reaction.The physical phase composition, pore structure parameters, microscopic morphology, chemical state and the present state of the active component Pd of the catalytic material were characterized by XRD, BET, SEM, XPS and TEM.This study then investigated the effects of active component loading, air velocity, reaction temperature and other conditions on the catalytic performance.The experimental results showed that the one-pot hydrothermal method successfully encapsulate Pd clusters within the pores of Silicalite-1 molecular sieve carriers to prepare highly dispersed sub-nanometer Pd cluster catalysts; the catalytic performance first increases and then decreases with the increase of Pd loading.This was due to the agglomeration effect between Pd atoms, resulting in the encapsulation of some Pd atoms and reducing the contact area between the active component and the reactants; in addition, using Silicalite-1 molecular sieve as a carrier can promote the conversion of active site skeletal oxygen to surface hydroxyl groups, which contributes to the catalytic oxidation of methane.The catalyst in this study excels existing methane catalytic process for its high catalytic activity, simple preparation, and low processing cost.

Optimization analysis of time frequency spectrum enhancement of tunnel blasting vibration signal

Fu Xiaoqiang, Ma Yan, Yu Jin, Dai Liangyu, Huang Lingjun

2023, 8(3): 348-356. doi: 10.19606/j.cnki.jmst.2023.03.008

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Aiming at the problem of insufficient time-frequency resolution of tunnel blasting vibration signal, a time-frequency image enhancement algorithm based on convolutional neural network is applied, through the time-frequency image enhancement of the measured tunnel blasting signal, the aggregation range of the blasting signal energy in the time-frequency domain is captured, and the real signal reflecting the blasting characteristics is reconstructed; according to the real signal, the initiation time of detonator in blasting network is accurately distinguished, and the characteristics of tunnel blasting detonator disaster source are identified.The analysis shows that the time-frequency image enhancement algorithm based on convolutional neural network can effectively suppress the cross-terms in the signal, retain the auto-terms of the signal to the greatest extent, and improve the energy aggregation and time-frequency resolution of the blasting signal; The mixed use of different batches of detonators is the main disaster causing factor of tunnel safety.Supervision should be strengthened to realize safe and efficient tunnel construction.

Research on rock-breaking effect of TBM hob and application of new type cutter

Liu Yingchao, Liu Bo, Jiang Yusheng, Jiang Hua, Li Ting

2023, 8(3): 357-369. doi: 10.19606/j.cnki.jmst.2023.03.009

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TBM hob wear is an important factor that affects the TBM tunneling efficiency and construction cost.Different blade types differ in rock breaking efficiency and wear.By analyzing the rock-breaking mechanism of the arc blade wedged hob, this study established the calculation model of hob normal cutting, and analyzed the influence of hob edge angle on normal cutting force.This study then designed three kinds of hobs with different cutter spacing and three types of hobs with different blade for rock breaking tests in laboratory.Results show that the reasonable cutter spacing is 15mm, sharp blade is prone to be worn, the tooth-like blade, which has higher rock breaking efficiency and wear resistance, is better than arc blade.Combined with the actual situation of the project site, a new hob with wedge-shaped blade is developed, which are applied to inclined shaft TBM tunneling at engineering site.Results show that the wear rate of the new wedge-shaped hob is 20 % less than that of the conventional ones, and the service life of former is longer than that of latter.Under the same geological conditions, new wedge-shaped hob can reduce the number of hobs consumption and improve efficiency of tunnelling.The development and application of the new type successfully solved the problems of hob wear and frequent replacement of hobs in the TBM inclined shaft excavation.It can provide technical support for TBM long distance inclined shaft driving, which not only shortened the construction period, but also saved the construction cost.

Research on the influence of steel fiber content on the axial compressive behavior of self-compacting concrete-filled steel tubular columns

Zhang Yi, Zhang Sibo, Kang Xinchao, Chen Qiyu, Wang Zetian, Yan Hao, Gao Qingli

2023, 8(3): 370-380. doi: 10.19606/j.cnki.jmst.2023.03.010

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In order to improve the axial compression bearing capacity of concrete filled steel tubular columns, steel fibers were added into self-compacting concrete.Through orthogonal test, the influence of 3 groups of steel fiber content on the strength of self-compacting concrete is studied, and the basis for the steel fiber content of concrete filled steel tube is provided.The axial compression tests of steel fiber reinforced concrete filled steel tubular columns and ordinary steel fiber reinforced concrete filled steel tubular columns were carried out to study the influence of steel fiber on the axial compression properties of self-compacting concrete filled steel tubular columns.Based on ABAQUS, 26 groups of concrete-filled steel tubular column models with different steel fiber content are established.After the correctness of the model is verified according to the field test results, the influence of six groups of steel fiber content on its axial compression performance is analyzed, and the calculation formula of the axial compression bearing capacity of concrete-filled steel tubular column with different steel fiber content is established.The results show that 2 % steel fiber has a significant contribution to the strength growth of self-compacting concrete, and can increase the axial compression bearing capacity of self-compacting concrete filled steel tubular columns by about 4 %.The calculation formula considering the increase of steel fiber content to the strength of concrete filled steel tube is proposed, which is in good agreement with the test results.

A high-precision positioning method for open-pit mine vehicles based on improved HMM deviation correction algorithm

Ruan Shunling, Li Meng, Gu Qinghua, Lu Caiwu

2023, 8(3): 381-389. doi: 10.19606/j.cnki.jmst.2023.03.011

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Vehicle location deviation could easily occur in complex road network of open-pit mines, which seriously affect production vehicle route planning and intelligent scheduling.In this light, this study proposed a method for high-precision positioning and rectification of open pit minecars based on an improved HMM(Hiddden Markov Model).Specifically, this study clipped the road section by the complex road network map of the constructed open-pit mine, and cleaned the positioning trajectory data of the minecart, whose density was sparsed and segmented; a buffer zone was established to search for candidate road points of the trajectory, so as to improve the efficiency of the minecart positioning and correction under the complex road network; the HMM optimization model of positioning deviation correction was established by calculating the positioning observation probability and transition probability of the minecart.The optimal deviation correctionwas conducted in combination with the Viterbi algorithm to achieve high-precision positioning and deviation correction of the open-pit minecart.Results indicate that the method produces a better correction effect than the original HMM positioning correction method, the correction accuracy can reach 89.2 %, and the average correction time is only 0.055 s.This could effectively correct the positioning coordinates of open-pit mine vehicles under complex backgrounds.

Study on fractal feature and settling velocity of tailings floc

Liu Xiaohui, Ruan Zhuen, Zhu Quanjie, Zhang Liqiang

2023, 8(3): 390-397. doi: 10.19606/j.cnki.jmst.2023.03.012

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Flocculent settling widely exists in various processes of tailings disposal.It bears significance for the accurate calculation of the flocculent settling velocity in engineering, such as tailings backfilling and surface disposal.This paper studied the structural characteristics of tailings flocs from the perspective of the fractal theory, and established the mathematical relationship between tailings particle size, geometry size of floc and fractal dimension.It analyzed the influence of buoyancy effect, reflux effect and viscosity effect on floc settling, and deduced a calculation formula of tailings flocculent settling velocity.This study carried out a tailings flocculent settling test observed the changes in geometric morphology of flocs by focused beam reflectance measurement technology(FBRM), and carried out validation analysis between testing data and model calculation value.The results showed that the settling velocity increased with the equivalent grain size of flocs, which could be divided into three stages, namely accelerated settling, uniform settling and compaction settling.The equivalent grain size of flocs of test tailings were 140~350 μm, and the settling velocity calculated by the formula were 1.3~2.0 mm/s when the fractal dimension was 2.25, which demonstrates significant correlation with the testing value, and had certain practical application value.

Quantitative characterization of coal mining damage and its application in numerical simulation

Zhang Cun, Ren Zhaopeng, Lan Shiyong, Fang Shangxin, Lu Jiale, Qiao Yuandong

2023, 8(3): 398-408. doi: 10.19606/j.cnki.jmst.2023.03.013

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Coal seam mining causes deformation, fracture and migration of overlying rock, further leading to the surface subsidence and ecological damage, which are the main manifestations of mining damage.Quantitatively characterize mining damage is the key to analyzing the stability of surrounding rock, designing mining parameters, and the premising of roadway support parameters.According to the finite element and discrete element simulation methods commonly used at this stage, this paper proposes a quantitative index(damage degree)to characterize mining damage: the proportion of zone plastic volume and the proportion of contact fracture length(number).On this basis, this study carried out the optimization of high-intensity mining parameters of the western mining area, the stability analysis of the coal pillar under the condition of mining and water immersion, and the progressive damage characteristics analysis of the roadway surrounding rock in the water-filled fault structure area by using the damage degree index.The quantitative relationship between the damage degree of the overlying rock and the mining parameters is obtained, which can realize the reasonable optimization of the mining parameters.This paper revealed the progressive damage characteristics of mining water immersion in coal pillars.We deemed that there is a danger of water seepage in the mined-out area as a water storage area under the existing coal pillar conditions.This study quantified the damage distribution characteristics of the surrounding rock in the roadway in the water-filled fault structure area, and proposed the corresponding? solution of dredging the fault through the roof aquifer, grouting reinforcement of the original fault fracture and strengthening the support.By comparing with common indicators such as the height of the water-conducting fracture zone and the width of the plastic development of the coal pillar, this research found that the damage degree indicators are more sensitive to the characterization of mining damage, and could realize continuous mining damage characterization.

Study on spatial characteristics of gangue slurry filling mining and engineering practice

Gu Wenzhe, Yang Baogui, Zhu Lei, Zhao Mengye

2023, 8(3): 409-418. doi: 10.19606/j.cnki.jmst.2023.03.014

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Coal gangue slurry filling and disposal of solid waste is a new coal green mining technology that conforms to the green and sustainable development of coal mines and responds to national environmental protection policies.In order to establish the basic theoretical system of slurry filling, this paper uses the methods of theoretical analysis, simulation experiment and field industrial test to reveal the law of overburden movement in slurry filling space and master the distribution characteristics of voids available for slurry filling, Clarify the function relationship of "gangue slurry goaf gap".The research shows that the "key layer of slurry filling" is the key to control the space range of slurry filling in the mining process, and the spatial evolution process of "arch beam shell" corresponds to the free accumulation area, load influence area and compaction area of slurry filling space, which directly determines the effect of gangue slurry; The porosity of the collapsed rock mass in the goaf varies along the strike and vertical direction, which satisfies the negative logarithmic function relationship.Based on this, the spatial void distribution model of slurry filling is established, and the key areas of slurry filling are pointed out; Through the ground in-situ grouting filling test, the filling characteristics of gangue slurry in goaf space are proved, and the action process of gangue slurry-gob gap has experienced three stages: initial flow, inrush flow and horizontal diffusion.The industrial practice of gangue slurry filling in the free accumulation area and load affected area of slurry filling space in Huangling No.2 well has successfully verified the feasibility of underground gangue slurry filling technology and the correctness of theory, which provides a new basis for gangue solid waste disposal and green mining.

Evaluation of soil quality in different reclamation areas of Hequ open-pit mine dump

Zhao Hongbao, Jiang Dongmei, Li Yue, Cheng Hui, Wu Tong

2023, 8(3): 419-427. doi: 10.19606/j.cnki.jmst.2023.03.015

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The open-pit mine has high mining efficiency, low cost, safe production and good economic benefits, but it also affects the structure and physical and chemical properties of the soil in the dump, resulting in the loss of soil nutrients and damage to land resources to a certain extent.Based on the nonlinear membership function method and the improved Nemero index evaluation method, five nutrient indexes were selected to comprehensively evaluate the soil fertility quality of Hequ open-pit mine.The research shows that the soil fertility quality index of different reclamation areas in Hequ open-pit mine is ranked as below 4(0.453)>1(0.447)>2(0.402)>3(0.213)>up 4(0.139), that is, the soil quality level of reclaimed area is higher than that of unreclaimed area.On the whole, the soil quality was at the lower or poor level, and the main limiting factors were organic matter, alkali-hydrolyzed nitrogen, available phosphorus, and soil pH.The results of this study can provide reference for soil improvement, soil fertility improvement and soil sustainable utilization in this area.for soil improvement, soil fertility improvement and soil sustainable utilization in this area.

The impact of transformation policies on the resilience of mining resource-based cities

Fan Zhongqi, Liu Qiyuan

2023, 8(3): 428-438. doi: 10.19606/j.cnki.jmst.2023.03.016

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Problems like a lack of diverse industries, environmental degradation and major social risks can lead to low resilience in resource-based cities.As part of a broader strategy to achieve high quality development, it therefore remains imperative to objectively assess the effects of transformation policies on the resilience of these cities.This will help to minimize urban risks and fill gaps in policy making.Based on the panel data of 278 prefecture-level cities from 2006 to 2020, this study proposed a two-way panel fixed-effects model using the PSM-DID method to examine the impact of the National Plan for Sustainable Development of Resource-based Cities(2013-2020) on urban resilience in promoting the transformation of resource-based cities.Through the present empirical analysis, we found that: the Plan does have a significant role to play in boosting urban resilience, but there is a policy lag; the mechanism analysis shows that the Plan raises urban resilience level mainly through optimizing industrial structure and improving housing conditions; the heterogeneity analysis shows that there are significant differences in the policy effects on different types of resource-based cities, among which declining resource-based cities exhibit the most significant improvement in their urban resilience.

2023 Vol. 8, No. 3