矿业科学学报

Failure mode and mechanism of mine waste dump with a soft and steep layer base

Wang Jiachen, Li Yangchun, Xu Wenbin, Luan Maoxu

2021, 6(2): 139-147. doi: 10.19606/j.cnki.jmst.2021.02.001

Abstract(586) HTML (181) PDF(35)

Abstract:
The waste dump of Tibet Jiama Copper Mine, which has a steep and soft base, is taken as the engineering background to reveal the failure mode and mechanism with assistance of similarity simulation principle.Using a method combining bottom friction test and numerical simulation.The deformation evolution of the waste dump is obtained by the contactless displacement monitoring system.The experimental results show that: ①The deformation and instability of the soft steep base dump can be divided into three stages: unloading deformation at the slope toe, vertical tensile crack penetration and tensile crack propagation.②The soft soil layer at the base is compressed and the soft soil layer at the slope toe is subjected to shearing.The slope toe is the trigger zone for slipping deformation and instability.③The potential slip surface passes through the soft soil layer to form an approximate circular arc slip surface.The instability failure of the soft-steep base dump mainly presents the modes of settlement, cracking and slippage.

Control theory of uniform strength support in deep roadway

Zuo Jianping, Wen Jinhao, Liu Dejun, Wu Lili, Sun Yunjiang

2021, 6(2): 148-159. doi: 10.19606/j.cnki.jmst.2021.02.002

Abstract(728) HTML (782) PDF(98)

Abstract:
In this paper, a large number of coal mine roadway failure cases are investigated, and 6 types and 15 typical failure forms are extracted.The mechanical characteristics and stress distribution of surrounding rock of typical roadway shapes such as circular and rectangular are analyzed.At present, the technology of high-strength prestressed bolt support, full space collaborative support and concrete filled steel tube support have shown certain advantages in deep surrounding rock control.Furthermore, based on the gradient failure mechanism of roadway surrounding rock and the uniform strength beam support model of rectangular roadway proposed by the author's team, the conceptual model of uniform strength support control theory for surrounding rock of deep roadway is put forward.According to the stress characteristics of roadway surrounding rock, the stress state of surrounding rock can be effectively adjusted by means of slotting and pressure relief, grouting, bolt (cable)support and passive support with concrete filled steel tube.The goal that the surrounding rock at different locations can reach the equivalent stress intensity state which is safe and matches the ground stress ratio can be achieved, and the ideal state that the stress distribution tends to be uniform and the plastic zone range of surrounding rock is similar can be obtained.The supporting strength of roadway with different buried depth and different section shape is calculated, and the calculation formula of support strength required by uniform strength is given.The stress changes of surrounding rock of circular and rectangular roadways before and after uniform strength support are simulated, and the stress field of surrounding rock can be significantly improved after uniform strength support is verified.Uniform strength support control model provide theoretical and practical guidance for surrounding rock control of deep roadway to a certain extent.

Experimental research on the fire-fighting effects of CO₂ on the recrudescence process of oxidized coal

Guo Zhiguo, Wang Rong, Zhang Jun, Chen Rongfang, Zhou Lingjian

2021, 6(2): 160-165. doi: 10.19606/j.cnki.jmst.2021.02.003

Abstract(353) HTML (175) PDF(7)

Abstract:
In order to master the fire-extinguishing efficiency of different concentrations of CO₂ on the oxidized coal re-combustion, a self-developed coal spontaneous oxidation program temperature increasing experimental device was adopted to study the inhibitory effect of CO₂ on coal oxidation and heating process, and the samples of Pingdingshan No.8 Coal Mine were fed with CO₂ concentrations of 10 %, 20 %, 30 % and 40 % respectively.The oxygen consumption rate, the production rate of CO and the change law of apparent activation energy of coal were measured, and the result shows that different volume fractions of CO₂ have inhibitory effects on the heating process of coal oxidation.The results show that different volume fractions of CO₂ have an inhibitory effect compared with the oxidation under pure air conditions.At the same time, the larger the volume fraction of CO₂ introduced, the lower the oxygen consumption and CO generation rate both the primary and secondary coal oxidation process, while the higher the apparent activation energy.That is to say, the larger the volume of CO₂, the better the inhibition efficiency of the re-combustion process of oxidized coal.

Geochemical characteristics and hydrocarbon generation potential evaluation of source rocks in the deepwater area of Qiongdongnan Basin

Li Jinshuai, Li Xianqing, Wang Yuan, Wang Gang, Xu Xinde, Liu Haiyu

2021, 6(2): 166-175. doi: 10.19606/j.cnki.jmst.2021.02.004

Abstract(691) HTML (669) PDF(39)

Abstract:
The deep-water area of Qiongdongnan Basin has a low degree of exploration.The evaluation of and research on the hydrocarbon generation potential of the marine-terrestrial transitional and marine source rocks in this area is related to the future direction of oil and gas exploration.Through organic carbon content(TOC)determination, rock pyrolysis analysis, microscopic composition identification, vitrinite reflectance(Ro) test and other experimental analysis, this paper systematically analyzes the geochemical characteristics and hydrocarbon generation potential of different types of source rocks in the deep water area of Qiongdongnan Basin.The results show that the source rock organic matter abundance in the deepwater area of Qiongdongnan Basin is the highest in the Yacheng Formation, with an average TOC of 1.37 %; the Lingshui Formation and Sanya Formation rank the second, with an average TOC of 0.91 % and 0.99 %; the Meishan group is relatively low, with an average TOC of 0.78 %.The degree of thermal evolution of organic matter is mainly in the mature stage of Oligocene, and the Miocene is mainly in the low-mature-mature stage.Organic matter types are mainly type Ⅲ in Oligocene, some are type Ⅱ₂, and Miocene are mainly type Ⅱ₂ and type Ⅲ.Comprehensive evaluation shows that the Yacheng Formation is a medium to good source rock with strong hydrocarbon generation potential; the Lingshui Formation and Sanya Formation are medium source rocks with relatively good hydrocarbon generation potential.

Investigation on the ultimate load bearing capacity of U-shaped steel arch support in coal bursting mine

Wang Hongwei, Deng Daixin, Jiang Yaodong, Shi Ruiming, Zhou Hongwei, Cui Shuai

2021, 6(2): 176-187. doi: 10.19606/j.cnki.jmst.2021.02.005

Abstract(460) HTML (233) PDF(24)

Abstract:
The damage degree of the surrounding rock in the coal mine roadway is closely related to the support form, thus to carry out research on the ultimate bearing capacity of U-shaped steel support in coal bursting mine is of important guiding significance for the prevention and control of coal burst.Taking a typical coal bursting mine in Yima Coalfield as the engineering background, a theoretical calculation mechanical model of U-shaped steel deformation under uniform loading is established and the analytical solution of the overall deformation is given, then deformation of U-shaped steel and roadway under the action of uniform and non-uniform load is compared, and the affordable ultimate load from overlying strata and applicable ultimate depth of U-shaped steel support is studied when the load increases.The change of approach amount and speed of the roadway roof and floor through on-site monitoring is obtained, and improving the bearing capacity of U-shaped steel support to control the deformation of roadway and coal burst is analyzed.The results show that: with the increase of load, there will be a sharp acceleration point in the deformation and strain energy of roadway, which can be used to determine the applicable ultimate depth of U-shaped steel support.The applicable ultimate depth of U-shaped steel under uniform loading is 1 600 m, and the value is 1 600 m under the non-uniform loading.When the ultimate depth is reached, U-shaped steel will be completely in failure state, and the deformation of roadway will increase rapidly.When designing U-shaped steel support for the roadway of coal bursting mine, it is very important to improve the contact condition of surrounding rock support and apply uniform load to the U-shaped steel support boundary to ensure good contact between surrounding rock and U-shaped steel, and improve the bearing capacity of U-shaped steel.U-shaped steel support with greater bearing capacity can absorb more energy released from surrounding rocks, and better control the approach amount between the roof and floor of the roadway, preventing the deformation of the roadway from increasing rapidly, thus the stability of the roadway is ensured and the coal burst in the roadway is effectively controlled.

The influence of the bedding angle under passive confining pressure on the dynamic strength and energy consumption of shale

Yang Guoliang, Bi Jingjiu, Zhang Zhifei, Li Xuguang, Liu Jie, Hong Peixuan

2021, 6(2): 188-195. doi: 10.19606/j.cnki.jmst.2021.02.006

Abstract(429) HTML (195) PDF(25)

Abstract:
In order to analyze the strength characteristics, damage characteristics and energy dissipation laws of the bedding shale specimens under passive confining pressure, the Hopkinson Pressure Bar(SHPB)device was used to perform different impact pressures and impact test(no confining pressure and passive confining pressure).The experimental research results show that under different impact pressure gradients, the damage degree of shale increases significantly with the increase of impact pressure gradient, and the bearing capacity of specimens decreases; the passive confining pressure condition significantly improves the anti-destructive ability of shale specimens.Transitioned from brittle failure to ductile failure under the condition of no confining pressure, the yield strength of the shale specimen is increased by 2.25~3.06 times, and the axial stress peak value is 1.8~2.5 times of that under the condition of no confining pressure; under the condition of passive confining pressure, the energy dissipation of shale specimens increases linearly with the increase of the average strain rate.It has a significant strain rate correlation within the strain rate range tested in this paper($\dot{\varepsilon} $ =97~520);shale has a significant transverse view Isotropic characteristics and bedding angle have significant effects on the strength characteristics, energy dissipation and damage characteristics of shale specimens.

Study on the gasket durability in the segment joint of subsurface excavated fabricated section

Dong Linwei, Yang Zhiyong, Jiang Yusheng, Wang Zhenyong, Wang Hao, Sun Ziyue, Qi Mingyu

2021, 6(2): 196-203. doi: 10.19606/j.cnki.jmst.2021.02.007

Abstract(452) HTML (192) PDF(8)

Abstract:
The aging of rubber will cause changes in the mechanical properties of materials, which in turn will cause waterproof failure.The section from the starting point of Beijing Metro Line 6 to Jin'anqiao is the first fabricated surface excavated tunnel in our country.It is of great significance to study the aging performance of the gaskets at the joints.The tunnel uses segments as the secondary lining structure, and EPDM gaskets as the waterproof material at the segment joints.In order to check whether the waterproof of the joints meets the durability requirements, an accelerated aging test was carried out on the rubber material of the gasket according to time-temperature equivalence principle, which predicts the service life of the rubber material.Due to the cumbersome calculation process of life prediction, the corresponding program was compiled to solve the problem of repeated trial calculation of parameters in the data processing.In addition, a numerical simulation of the stress of segment gaskets was carried out, and the influence of aging on the waterproof of the gasket was analyzed.It was pointed out that the designed water pressure of the gasket was increased to at least 1.75 times of the original one.

Study on water absorption and pore structure fractal characteristics of slag-based geopolymer

Chen Zhen, Zhang Zengzhi, Wang Lining, Wang Han, Zhang Shangsheng

2021, 6(2): 204-209. doi: 10.19606/j.cnki.jmst.2021.02.008

Abstract(303) HTML (483) PDF(28)

Abstract:
To explore slag-based geopolymer porous material under the condition of different porosity, pore diameter distribution of performance and improve the mechanism of water absorption, the experiments on the water absorption, water release properties of the slag-bnsed geopolymer were Conducted, with blast furnace slag, fly ash, and sodium silicate as the main raw material, and hydrogen peroxide as foaming agent, Image analysis softwares and the fractal theory were adopted to analyze its microstructure and pore structure fractal characteristics.The results show that the porosity, maximum pore size and water absorption of the porous material increase with the increase of the foaming agent, while the time needed to release water per unit mass and fractal dimension of the pore surface decrease.When the dosage of foaming agent is 1.6 ml, the water absorption rate of the material reaches 62 %, and the time required to release water per unit mass is only 1.38 h.At this point, both water absorption and water release properties of the material are taken into account.

Study on operation condition of an in-situ carbon capture gasification based on transport reactor

Chi Jinling, Li Keying, Mao Longgan, Sha Yanming

2021, 6(2): 210-217. doi: 10.19606/j.cnki.jmst.2021.02.009

Abstract(320) HTML (269) PDF(11)

Abstract:
In order to solve the problem of low carbon conversion rate in the conventional in-situ carbon capture gasification process based on fixed bed or bubbling fluidized bed reactor, in this paper, a transport bed is applied as the reactor of the in-situ carbon capture gasification for hydrogen production.The dynamic model of the reactor combining hydrodynamic models and reaction kinetic models is built to investigate the operation feasibility and influence of key parameters, such as steam to carbon ratio, operation temperature and pressure, on reactor performance.The study concludes the operational conditions of the reactor when it has operational feasibility.Meanwhile, results show that, take a small test transport equipment as basis, the reactor is recommend to operate at pressure of 900 kPa, temperature of 800 ℃ and steam to carbon ratio of 2.Under this condition, the H₂ composition in the dry gas could reach 82 % together with the carbon conversion of 60 %.The results confirmed the feasibility of the transport bed as the in-situ carbon capture gasification reactor and its advantage in improving the in-situ carbon capture gasification performance, determined the ranges of reactor operation conditions, which provide a reference for the development of hydrogen production technology by in-situ carbon capture gasification.

Gait recognition method of coal mine personnel based on Two-Stream neural network

Liu Xiaoyang, Liu Jinqiang, Zheng Haolin

2021, 6(2): 218-227. doi: 10.19606/j.cnki.jmst.2021.02.010

Abstract(445) HTML (212) PDF(22)

Abstract:
Biometric methods such as human faces, fingerprints, and irises are relatively mature, but the images of these biometric methods often become blurred under the limitations of the complex underground environment, which leads to the problem of low identification rate of underground coal mine personnel.To solve this problem, a Two-Stream neural network(TS-GAIT)gait recognition method is proposed based on the residual neural network and the stacked convolutional autoencoder in this paper.The residual neural network is mainly used to extract the dynamic deep features containing spatiotemporal information in the gait pattern.The stacked convolutional autoencoder is used to extract the static invariant features containing physiological information.Moreover, a novel feature fusion method is adopted to achieve the fusion and representation of dynamic and static invariant features.The extracted features are robust to angle, clothing and carrying conditions.The method is evaluated on the challenging CASIA-B gait dataset and the collected gait dataset of coal miners(CM-GAIT).The experimental results show that the method is effective and feasible for gait recognition of underground coal mine personnel.Compared with other gait recognition methods, the accuracy rate has been significantly increased.

Lignite reverse flotation test process and mechanism

Ning Kejia, Cui Jiahua, Xu Hongxiang, Wang Penghui, Lei Wenjie, Huang Bo, Deng Jiushuai

2021, 6(2): 228-236. doi: 10.19606/j.cnki.jmst.2021.02.011

Abstract(274) HTML (176) PDF(16)

Abstract:
This paper takes the lignite coal sample from Baori Hiller of Inner Mongolia as the research object.Through the coal flotation reverse flotation test and orthogonal test, the surface characteristics and flotation characteristics of lignite were analyzed and studied, and the types, dosages and processes of the lignite flotation were investigated.The results showed that the de-flotation effect of dodecyl amine(DDA)on lignite was better than that of octadecyl amine(ODA)and cetyltrimethylammonium bromide(CTAB).When the DDA dosage is 1 400 g/t, the reverse flotation efficiency is 6.89 %, the floating tail minimum ash is 11.23 %, the floating tail yield is 84.46 %, and the maximum difference between the floating fine and floating tail ash is 5.25 %. When the dosage of DDA is fixed and the dosage of dextrin is 1 600 g/t, the floating ash is divided into 15.58 %, the floating ash is 10.77 %, and the difference is 4.81 %; The effect of the amount of DDA, dextrin and octanol on the yield of floating tail was not significant, while the effect of DDA on floating tail ash was significant, but the effect of dextrin and octanol on floating tail ash was not significant.For lignite, continuous low-floating(10.20 %)and high recovery(up to 70 %)of clean coal can be obtained by successive multiple reverse flotation processes.Amine collectors have a good collection effect on minerals such as quartz, silicate and carbonate in lignite due to their physical adsorption and complex adsorption.In the pulp, the hydrogen atoms in the dextrin interact with a large number of strongly electronegative atoms such as oxygen and nitrogen present on the surface of the lignite to form a strong hydrogen bond, thereby forming a hydrophilic film on the surface of the coal particles, so that the coal particles become hydrophilic and suppressed.

Optimization of flotation reagent system of coal slime based on uniform experimental design

Deng Zilin, Hou Ying

2021, 6(2): 237-243. doi: 10.19606/j.cnki.jmst.2021.02.012

Abstract(351) HTML (133) PDF(18)

Abstract:
In order to study the influence of flotation reagent system on coal slime flotation, the coal slime of Shuiyu Coal Washing Plant is taken as the research object.Based on the uniform experimental design(UED)method, the mathematical model between flotation effect and reagent dosage is established, and the effect of collector and frother dosage on flotation effect is investigated.The results show that the flotation effect of coal slime is only related to the amount of frother in a certain range of collector dosage; the optimal dosage of frother is 75 g/t, the appropriate dosage of collector is 130 g/t.Compared with the actual production dosage, under the conditions of 257 g/t collector and 143 g/t frother, and the ash content of clean coal kept unchanged, the yield of flotation clean coal is increased by 0.49 %, the combustible material recovery is increased by 0.50 %, the improvement index of flotation is increased by 0.17 %, the dosage of collector is reduced by 127 g/t, and the dosage of frother is reduced by 68 g/t.When the collector dosage is within a certain range, the frother dosage is the key factor affecting the flotation effect, and the appropriate frother dosage can significantly improve the coal slime separation effect.

Research on public ecological environment risk information acquisition in large coal-fired power base development

Ma Yan, Wang Ziyuan, Cao Zhiguo, Kang Yining, Yan Bei, Sun Xiang, Lu Zhaohua, Zhang Meng

2021, 6(2): 244-254. doi: 10.19606/j.cnki.jmst.2021.02.013

Abstract(540) HTML (210) PDF(12)

Abstract:
The acquisition and communication of ecological and environmental risk information can effectively mitigate the social risks caused by ecological and environmental damage in coal power base.According to the risk information seeking and processing model (RISP), a questionnaire survey was conducted on the social population around Xilinhaote coal power base.The acquisition and preference of ecological risk information during the development of coal-fired power bases was quantitatively analyzed.The results show the following four points: The probability of inadequate access to eco-environmental risk information of coal-fired power base is as high as 51.5 %.The Internet as a source of risk information is favored by 53.4 % of the public, and the probability of public expressing trust in eco-environmental risk information of various channels is as high as 50 %, and the probability of distrust in eco-environmental risk information with data is significantly reduced to 14.6 %.Herdsmen's adequacy and ability of risk information acquisition are relatively low, and the risk information acquisition channel is traditional and single.Improving residents' educational level can effectively improve the adequacy of information acquisition and enrich the access to risk information.Compared with protection policies, the respondents are in favor of eco-environmental protection measures, such as vegetation planting, enclosure, etc.which are carried out in a direct and effective way.It is suggested that that the mechanism of public participation targeted at the social groups be established, risk education through various channels be enhanced and long-term information communication mechanism be implemented during the whole process of the development in coal and electricity bases.

2021 Vol. 6, No. 2