矿业科学学报

The model of spatial analogous hyperboloid for three-dimensional rock strata movement in mining engineering

Zuo Jianping, Li Ying, Li Hongjie, Yu Meilu, Wu Zuoqi, Liu Jiashun

2023, 8(1): 1-14. doi: 10.19606/j.cnki.jmst.2023.01.001

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Abstract:
Based on a large number of field investigations and the analysis of the "analogous hyperbolic" overall movement model proposed by the author, this paper further extends it to three-dimensional space, and proposes a full-space "analogous hyperboloid"three-dimensional movement model of the mining strata.There are two types of hyperboloids, "quasi-single-leaf"and "quasi-double-leaf", which can approximately describe the three-dimensional movement and surface subsidence characteristics of full-space mining strata under different lithological conditions.The "analogous single leaf hyperboloid" model is a horizontal moving boundary model of the spatial rock layer, which is implicit in the thick loose layer overlying rock; the "analogous double leaf hyperboloid" model is the vertical movement of the spatial surface subsidence and the overlying fissure arch and caving arch.The boundary models are approximately symmetrical with the "origin" in the main key layer, and are embodied in external forms such as surface subsidence under mining disturbance and arch caving of the surrounding rock in the stope. Through theoretical analysis, similar model test and 3DEC numerical simulation, this paper deduces and proves in detail the "analogous hyperboloid" model of spatially mined rock strata movement and surface subsidence under the condition of near-horizontal coal seam mining in thick loose layers.At the same time, this study analyzed the composition conditions, influencing factors and overall migration law of the co-asymptotic conical surface "analogous hyperboloid" model.Results show that under the condition of near-horizontal coal seam mining with thin bedrock and thick loose layer, the "quasi-hyperboloid" theoretical model is in good alignment with the 3DEC simulation results, indicating that the overlying rock migration and surface subsidence in space mining are "analogous hyperboloid" feature.

The key causes and characteristics of spontaneous combustion of coal seams affected by igneous intrusion

Qin Botao, Shi Quanlin, Qu Bao, Liu Jinlong

2023, 8(1): 15-25. doi: 10.19606/j.cnki.jmst.2023.01.002

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Abstract:
In order to find out the key causes of changes in spontaneous combustion characteristics of igneous intrusive coal seams, this paper took the Daxing Coal Mine in Tiefa Coalfield as example for analysis, which was widely invaded by igneous and had serious coal spontaneous combustion disasters.Metamorphic coal and unaffected primary coal were collected from the study area.Specifically, this paper studied the patterns of heat production and temperature rise, gas production rules, and microscopic structure parameters of coal samples by synchronous thermal analyzer and coal spontaneous combustion characteristic measuring device.The experimental results show that the igneous intrusion caused the mutation in the spontaneous combustion characteristics of the coal.Compared with the primary coal, there was significantly higher oxidation heat release of the metamorphic coal at the low temperature stage.Also, the crossing point temperature of metamorphic coal was reduced by 13.2 ℃, and it entered the stage of oxidation and weight gain earlier than the primary coal.When the environment temperature exceeded 90 ℃, the oxidation heat generation and reaction rate of metamorphic coal increased rapidly, which showed higher oxygen consumption rate and faster generation rate of oxidative gas products such as CO and CO₂.This demonstrated higher oxidation activity of metamorphic coal than that of primary coal.The analytic results of physicochemical microstructure showed that the high temperature and pressure of igneous intrusion changed the pore structure of coal, which reduced the pore volume and specific surface area of micropores/mesopores in metamorphic coal, and the pore volume of macropores was three times higher than that of primary coal.The average pore size and porosity increased significantly, which was conducive to the transport, migration and adsorption reaction of oxygen molecules in the coal structure.At the same time, igneous intrusion reduced the oxygen-containing functional groups of metamorphic coal, and the content of aliphatic hydrocarbons with higher activity increased from 27.98 % to 29.07 %, which enhanced the oxidative activity of metamorphic coal.Moreover, igneous intrusion caused problems such as increased air leakage, long oxidation time of left coal, and wide oxidation zone during the mining, eventually leading to severe coal spontaneous combustion disasters.

Adaptive intelligent cutting technology of the shearer based on the high-precision three-dimensional dynamic geological model

Hou Yunbing, Zhang Hong, Mao Shanjun, Sun Zhenming, Li Mei, Chen Huazhou

2023, 8(1): 26-38. doi: 10.19606/j.cnki.jmst.2023.01.003

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Abstract:
If the shearer is cutting coal using the "memory cutting" technique, a manual demonstration is required.The memory cutting technology has higher requirements on the reserving conditions of coal seams.When the coal seam fluctuates greatly, frequent manual demonstrations are required.The "memory cutting" technology only optimizes the cutting path of the coal seam roof for the next cutting.Along the advancing direction of the shearer, it is impossible to accurately plan and control the pitching angle of the shearer according to the reserving conditions of the coal seam.Based on the concept of shearer self-adaptive intelligent cutting, this paper designs the operation mode of the shearer intelligent cutting system in the fully mechanized working face.In this model, the high-precision three-dimensional geological model of the working face is first constructed by using the highly accurate geophysical data of the coal seam, and then the future cutting path of the shearer is planned by using the model.At the same time, the high-precision three-dimensional geological model is dynamically corrected by using the latest geological data of the working face during the mining process.In this paper, the high-precision three-dimensional dynamic geological model is coupled with the shearer mining planning algorithm.According to the model, a shearer mining control baseline planning algorithm that can adapt to the changes of the coal seam is proposed, which realizes the pitching control of the shearer in the advancing direction and the cutting control in the pulling direction, as well as the efficient cooperation between the update of the geological model, the planning of the mining baseline and the adjustment of the shearer drum.The calculation service interface of the drum adjustment parameters in the intelligent cutting system and the communication protocol between the intelligent cutting system is designed.Addtionally, the shearer control system is considered.This realizes the precise control of the shearer drum based on the planning cutting path.The intelligent cutting system of fully mechanized working face is applied to guide the production of shearers.The practice shows that the shearer intelligent cutting system is suitable for coal seams with various degrees of floor inclination.The cutting line of the shearer can better fit the roof and floor lines of the coal seam, which can save resources and improve production efficiency.

Research on the new technology of anchor cable with C-shaped tube support and its application in deep large deformation roadway

Shan Renliang, Tong Xiao, Dai Weilin, Wang Zhaorui, Liu Song, Li Yongzhen, Liu Dong, Chen Mingyuan

2023, 8(1): 39-49. doi: 10.19606/j.cnki.jmst.2023.01.004

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Abstract:
With the increase of coal mining depth, the stress environment of the surrounding rock of the roadway deteriorates, therefore it becomes a prominent problem for the large deformation of the surrounding rock and the breaking of the bolt and cable, which seriously affects the safety of deep mine production.To solve such problems, this paper focuses on the advantages and disadvantages of bolt and cable support.Based on the interaction mechanism between Anchor Cable with C-shaped tube(ACC)and surrounding rock, this paper proposed a new ACC support technology.ACC optimizes the stress state by improving the structure of the free section of the anchor cable.It can not only enhance the anchor cable's axial bearing capacity but also prevent the free section of the anchor cable from breaking due to lateral action.It can avoid the problem of instability of surrounding rock.Through the shear test, it is found that the maximum shear load of the ACC is more than 1.27 times that of the ordinary anchor cable, and the average maximum shear displacement is 1.16 times that of the ordinary anchor cable, which indicates that the ACC has good shear resistance and shear direction extension properties.Based on the engineering case of the roadway of Jiulong Mine, this study analyzes the deformation and failure characteristics of the roadway under the original support scheme through on-site monitoring and borehole detection, and has successfully applied the ACC in the deep large-deformation roadway.The field monitoring results show that the new technology of ACC can effectively control the large deformation of surrounding rock.The results of this study can provide reference for similar deep mine support.

Research of high pre-stress NPR support technology in deep shaft roadway engineering

Sun Xiaoming, Zhang Yong, He Manchao, Yang Jinkun

2023, 8(1): 50-65. doi: 10.19606/j.cnki.jmst.2023.01.005

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Abstract:
Deep coal resources are the crucial backup for China's energy security in the future. However, large deformation and instability of rock mass in deep roadway engineering still poses serious problems in the deep "three high and one complex" geomechanical environment. Therefore, this study departed from the support surrounding rock interaction and developed a series of NPR anchor bolts/cables with high strength, high constant resistance and large deformation mechanical properties. It constructed the constitutive equation of NPR anchor bolts, and carried out comprehensive mechanical tests indoor and on-site to verify the unique mechanical properties of NPR anchor bolts/cables. This study analyzed the interaction relationship between NPR support and surrounding rock, derived the constitutive relationship of rock mass supported by NPR, and elucidated the excavation compensation mechanical effect after adopting NPR coupling support, which revealed the high pre-stress NPR coupling support mechanism. By drawing on the actual working conditions of Daqiang Coal Mine, this study proposed the NPR support technology for intensive chambers group of deep pump house suction well with NPR bolt /cable as the core. The numerical analysis and field monitoring data show that the high prestress NPR coupling support technology can significantly improve the bearing characteristics of the support surrounding rock, effectively reduce the distribution and development range of the plastic zone of the rock mass in the roadway engineering, homogenize the support surrounding rock stress field, and reduce the overall deformation of the surrounding rock by more than 68 %, ensuring the long-term stability of the rock mass in the deep roadway engineering. The research results can provide reference for stability control of deep roadway engineering under similar conditions.

The drilling parameter acquisition system of hydraulic anchor drilling rig in coal mine roadways and its application

Yue Zhongwen, Dai Shiqing, Li Yang, Yue Xiaolei, Li Shihui, Cao Wu

2023, 8(1): 66-73. doi: 10.19606/j.cnki.jmst.2023.01.006

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Abstract:
The drilling identification technology of surrounding rock lithology can obtain the mechanical parameters of the surrounding rock of the roadway in real time, providing the basic guarantee for the surrounding rock support of the coal mine roadway. Based on the hydraulic anchor drilling rig for coal mine roadways, this paper developed the drilling parameter acquisition system of hydraulic anchor drilling rig in coal mine roadways, including the drilling system, power system, monitoring system and specimen platform. Drilling experiments of combined specimens of mortar of different strengths were carried out using this system. The experimental results indicate that the system shows good performance, obvious variation of the parameters with drilling, and obvious transitions of torque and propulsion pressure at the junction of different rock formations. In order to verify the feasibility of identifying rock strength while drilling, this study calculated the relationship between rock breaking specific energy by means of drilling parameters, and also analyzed the relationship between drilling parameters and compressive strength, it shows that based on the rock breaking specific energy method, the system can realize the identification of rock mechanical parameters by drilling parameters.

Deformation, seepage and energy evolution characteristics of gas-bearing coal-rock under intermediate principal stress

Wang Kai, Zhao Enbiao, Guo Yangyang, Du Feng, Wang Long

2023, 8(1): 74-82. doi: 10.19606/j.cnki.jmst.2023.01.007

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Abstract:
In deep mining, coal-rock is in a state of three unequal forces, and the intermediate principal stress has the influence on the deformation and strength characteristics of coal-rock. This study studied the deformation and seepage characteristics of gas-bearing composite coal-rock under different intermediate principal stresses by using true triaxial gas-solid coupling seepage test device for coal and rock. The results show : ① With the increase of intermediate principal stress, the strain in the direction of maximum principal stress first increases and then decreases when the peak strength is reached, and there is widening gap between the strain in the direction of intermediate principal stress and the strain in the direction of minimum principal stress.② Under low intermediate principal stress, the strain in the intermediate principal stress direction shows expansion and deformation, and when there is relatively high intermediate principal stress, the ε₂-Δσ curve reaches the peak and then bounces back, and the strain in the intermediate principal stress direction finally shows compression and deformation.③ With the increase of intermediate principal stress, the trough value of relative permeability coefficient decreases, and the peak inflection point of relative permeability coefficient curve is consistent with the inflection point of ε₁-Δσ curve.④ When the stress peak is reached, the total input energy of the specimen first increases and then decreases, which is similar to the changes of the specimen strength: The elastic strain energy first increases and then decreases, the dissipative energy continues to increase, U_e/U first increases and then decreases, and U_d/U first decreases and then increases.

Research on the influence of blasting vibration on high-rise building near subway station

Sun Zhongbo, Zhao Yixin, Wang Hailiang, Ren Jiandong

2023, 8(1): 83-92. doi: 10.19606/j.cnki.jmst.2023.01.008

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Abstract:
Making clear the vibration response law of buildings(structures)due to blasting is of great significance both engineeringly and the economically. By conducting blasting experiment at subway station entrance A, the vibration signal of building NO.2 was analyzed through Hilbert-Huang transform. Results indicate that as height increases, the three-vector peak vibration velocity attenuate sharply, and then shows a wave-shaped change in the middle and amplify on the top floor, which was divided into attenuation area(0~26.15 m], fluctuation area(26.15~71.75 m]and amplification area(71.75~94.55 m]. The shape of the Hilbert spectrum gradually changes from three-peak to single-peak, the dominant frequency band attenuates from 75~125 Hz to 10~40 Hz and the energy amplitude decreases. This demonstrates that the lower vibration frequency of the floor in the amplification area could easily cause resonance. Based on the composition of the top-level energy spectrum fitted by the ground measuring points, it is verified that the essence of the top-level amplification effect is to selectively amplify the energy close to the natural frequency of the building in the blasting seismic wave.

SHPB tests and analysis of lunar soil simulant under different negative temperatures and water contents

Ma Qinyong, Bao Xiaoxuan

2023, 8(1): 93-101. doi: 10.19606/j.cnki.jmst.2023.01.009

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Abstract:
In order to study the dynamic mechanical properties of the frozen lunar soil in the permanent shadow area of the moon, the basaltic lunar soil simulant was used as the research object, and the dynamic impact test was performed on it. The dynamic stress-strain curve, dynamic compressive strength and failure of simulated lunar soil under different negative temperature, different moisture content and different strain rate were studied. The relationship between dynamic compressive strength, dynamic elastic modulus and simulated lunar soil temperature, moisture content and strain rate was analyzed. The test results show that the dynamic compressive strength is positively related to the strain rate; the failure modes are mainly conical shear failure and granular crushing failure; the fragmentation distribution has good fractal characteristics. Provide reference for future research on lunar building materials.

Application progress of molecular simulation in phosphate ore flotation

Zhang Qin, Li Xianbo, Mao Song, Zhang Tiebin

2023, 8(1): 102-114. doi: 10.19606/j.cnki.jmst.2023.01.010

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Abstract:
Flotation is the main method to improve the quality and reduce the impurity of calcium magnesium phosphate ore. However, the similar surface physical and chemical properties of dolomite and fluorapatite make it difficult to separate efficiently. With the development of quantum mechanics and computational chemistry, molecular simulation has gradually become an effective tool for studying the flotation of calcium magnesium phosphate ore. It provides a new method for studying the crystal chemical properties of the main minerals in calcium-magnesium phosphate ore and the interaction between mineral interfaces. On the basis of reviewing the research, especially the wettability, surface electricity and surface adsorption characteristics, this paper summarizes the methods of molecular simulation, and the application of density functional theory(DFT)and molecular dynamics simulation(MDS)in the flotation separation of fluorapatite and dolomite, including the chemical properties of crystals, the interaction of water molecules and reagents with mineral surfaces. In addition, the application prospects of molecular simulation in phosphate ore flotation research are also discussed.

Review of environmental impact of comprehensive utilization of phosphogypsum

Xu Jinhui, Shao Longyi, Hou Haihai, Li Jinjuan, Liu Junxia, Huang Man, Wang Xiuying, Lu Jing

2023, 8(1): 115-126. doi: 10.19606/j.cnki.jmst.2023.01.011

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Abstract:
Phosphogypsum is a kind of industrial solid waste produced by wet phosphoric acid. Although there is an increase in the utilization rate of phosphogypsum, its consumption is limited. At present, it is still treated through accumulation, which will not only occupy land resources, but also causes serious environmental pollution. This paper reviews the discharge and comprehensive utilization of phosphogypsum in China, and analyzes the environmental impact of phosphogypsum, which is mainly manifested in the storage process: ①The atmospheric influence induced by hydrogen fluoride gas, radionuclides, heavy metal elements adsorbed by nanoparticles and the greenhouse effect; ②The variation of water pH, the abnormality of heavy metal content, the living environment of phytoplankton and the imbalance of Marine phosphorus cycle; ③Influence of soil pH and heavy metal content on soil environment. For the purpose of resource conservation and environmental protection, considering the current situation of comprehensive utilization and treatment of phosphogypsum, the technical innovation of phosphogypsum disposal, the monitoring and evaluation of pollutant discharge from phosphogypsum storage sites, and the study of environmental toxicological effects of phosphogypsum storage sites should be the focus of future research.

Preparation of CaCl₂-heat treated coal slime based composite catalytic material and its performance toward phenol degradation by activating peroxymonosulfate

Wang Qizhou, Li Chunquan, Yin Shuaijun, Sun Zhiming

2023, 8(1): 127-136. doi: 10.19606/j.cnki.jmst.2023.01.012

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Abstract:
Based on the current situation of comprehensive utilization of coal slime in China and the urgent need for water pollution control in coal mining areas, this paper uses coal slime(CS)as raw material and CaCl₂ as the activator, different proportions of coal slime-based catalytic materials were prepared under anaerobic calcination, which were characterized by XRD, SEM, BET, FT-IR, XPS, Raman spectroscopy, etc. This study investigated its ability to activate peroxymonosulfate(PMS)for the catalytic degradation of phenol in wastewater. Results show that the catalytic material prepared by CaCl₂-heat treated coal slime can effectively activate PMS to achieve the highly efficient degradation of phenol. In addition, when the mass ratio of coal slime and CaCl₂ reach 4∶3, it shows the optimal degradation performance, whose degradation rate of phenol can reach 100 %. The active species ¹O₂ played a major role in the degradation system. Moreover, the catalytic materials could be applied in a wide pH range(3.0~11.0), and the influence of various anions in water on the degradation of phenol is relatively limited, indicating their good application prospect in wastewater treatment.

2023 Vol. 8, No. 1