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Zhang J, Yang K, He X, Zhao X, Wei Z, He S. Research status of comprehensive utilization of coal-based solid waste (CSW) and key technologies of filling mining in China: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:171855. [PMID: 38522538 DOI: 10.1016/j.scitotenv.2024.171855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 03/06/2024] [Accepted: 03/19/2024] [Indexed: 03/26/2024]
Abstract
Coal-based solid waste (CSW) is the solid waste generated in the process of coal mining, washing and pyrolysis, which is an important industrial solid waste. The comprehensive utilization of CSW is a key link in the process of clean and efficient utilization of coal, and the use of CSW for coal mine filling mining is an important means of "harmless, resourceful and large-scale" utilization. In order to study the research status of comprehensive utilization of CSW and key technologies of filling mining in China, this paper combs and analyzes the current situation of comprehensive utilization of CSW from three parts, namely, physical and chemical properties of CSW, Industry-related policies, and ways and means of comprehensive utilization. It is found that coal mine filling mining is a green disposal method with relatively reliable technical means, low supervision cost and large-scale disposal of CSW in the comprehensive utilization of CSW in China. Furthermore, an analysis was conducted on the current research status of key technologies in the CSW filling and mining process, including the integration of "mining, selection and filling", adsorption and complexation passivation of heavy metals in CSW, the preparation of CSW collaborative filling materials, and monitoring and control of the whole filling process, etc. Based on the above analysis and research, it was pointed out that there were some problems, namely: (1) large output of CSW and low level of comprehensive utilization; (2) high investment and high cost of CSW filling and mining; and (3) imperfect CSW waste filling mining theory and technology. In response to these issues, prospects have been made from the aspects of policy incentive mechanisms, collaborative utilization of CSW with multi-industry links, and the theory and technology of CSW filling mining. This study provided reference and inspiration for the comprehensive utilization of CSW in the world, and provides guidance for the large-scale promotion and application of CSW filling mining methods.
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Affiliation(s)
- Jiqiang Zhang
- Key Laboratory of Safe and Effective Coal, Mining Ministry of Education, Anhui University of Science and Technology, Huainan 232001, Anhui, China; School of Mining Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui, China.
| | - Ke Yang
- Key Laboratory of Safe and Effective Coal, Mining Ministry of Education, Anhui University of Science and Technology, Huainan 232001, Anhui, China; Institute of Energy, Hefei Comprehensive National Science Center, Hefei 230031, China; School of Mining Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui, China.
| | - Xiang He
- Key Laboratory of Safe and Effective Coal, Mining Ministry of Education, Anhui University of Science and Technology, Huainan 232001, Anhui, China; School of Mining Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui, China
| | - Xinyuan Zhao
- Key Laboratory of Safe and Effective Coal, Mining Ministry of Education, Anhui University of Science and Technology, Huainan 232001, Anhui, China; School of Mining Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui, China
| | - Zhen Wei
- School of Civil Engineering, Lanzhou Institute of Technology, Lanzhou 730050, Gansu, China
| | - Shuxin He
- Key Laboratory of Safe and Effective Coal, Mining Ministry of Education, Anhui University of Science and Technology, Huainan 232001, Anhui, China; School of Mining Engineering, Anhui University of Science and Technology, Huainan 232001, Anhui, China
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Zhao X, Yang K, He X, Wei Z, Zhang J, Yu X. Mix proportion and microscopic characterization of coal-based solid waste backfill material based on response surface methodology and multi-objective decision-making. Sci Rep 2024; 14:5672. [PMID: 38453995 PMCID: PMC10920910 DOI: 10.1038/s41598-024-56028-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 02/29/2024] [Indexed: 03/09/2024] Open
Abstract
The mix proportion of multi-source coal-based solid waste (CSW) for underground backfilling affects transportation and support performance of backfill materials, and even the backfilling cost. In this study, the optimal mix proportion of desulfurization gypsum (DG), furnace bottom slag (FBS) and gasification fine slag (GFS) is determined by the Response Surface Methodology-Box Behnken Design (RSM-BBD). Then the fluidity, bleeding rate, 3-day strength, 7-day strength and preparation cost are evaluation indicators, the optimal mix proportion of backfill materials is determined by the multi-objective decision-making method (MDM). Finally, the microstructure of the backfill material with optimal mix proportion was studied by TGA, MIP, SEM-EDS and XRD. The results show that the mix proportion of CSW with the optimal comprehensive index is coal gangue (CG): coal fly ash (CFA): DG: FBS: GFS = 1:1.5:0.2:0.1:0.1, the mass concentration is 78%, and ordinary Portland cement (OPC)/CSW = 7.5%. The weight loss phenomenon of the backfill material with the optimal mix proportion occurs continuously during the heating process, mainly due to the evaporation of crystal water, structural water and hydroxyl water. There are dense narrow-necked pores in the backfill material, and the pore connectivity is poor. There is no hydration reaction occurs between CSW particles, and the strength increase of the backfill material mainly depends on the hydration reaction of cement. In ettringite, part of Al2O3 is replaced by SiO2, and part of CaSO4 is replaced by CaCO3. This study provides a reference for the engineering application of underground backfilling with multi-source CSW.
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Affiliation(s)
- Xinyuan Zhao
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China
| | - Ke Yang
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China.
- Institute of Energy, Hefei Comprehensive National Science Center, Hefei, 230031, Anhui, China.
| | - Xiang He
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China
| | - Zhen Wei
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China
| | - Jiqiang Zhang
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China
| | - Xiang Yu
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China
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Ju Y, Nie X, Zhu Y, Wang K, Zhou H, Ge S. Stress distribution and roof subsidence of surrounding strata considering in situ coal conversion and CO 2 mineralization backfilling: Photoelastic experiments using 3D-printed models of mining faces and goafs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169368. [PMID: 38104844 DOI: 10.1016/j.scitotenv.2023.169368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 12/04/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
Coal, a reliable and economical fuel, is expected to remain the primary energy source for power generation for the foreseeable future. However, conventional mining and utilization of coal has caused environmental degradation and infrastructure damage. An in situ coal conversion method has been proposed to mitigate environmental problems and reduce CO2 emissions resulting from coal extraction and utilization. This method involves the in situ conversion and utilization of coal, backfilling of waste rock, and CO2 mineralization to backfill the goaf. In this study, the impact of mining and conversion activities on the surrounding strata was evaluated to ascertain the effectiveness and advantages of the in situ coal conversion method. Transparent stope models were created using three-dimensional printing technology. The stress distribution and deformation characteristics of the surrounding strata were examined using photoelasticity and digital image correlation methods. The results were compared with those obtained using the traditional backfill mining method. The comparison revealed that the disturbance to the surrounding strata was 14.4 times less in the in situ conversion method than in the traditional backfill mining method. Additionally, the disturbance height at the roof and the disturbance depth at the floor were 4.2 and 2.1 times lower, respectively. The roof subsidence in the in situ conversion method was 1.97 times less than that in the traditional backfill mining method. These results confirm the advantages of minimizing the disturbance to surrounding rocks and controlling the subsidence of roof strata.
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Affiliation(s)
- Yang Ju
- State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China; School of Energy and Mining Engineering, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China; School of Mechanics and Civil Engineering, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China.
| | - Xiaodong Nie
- School of Mechanics and Civil Engineering, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China
| | - Yan Zhu
- China Academy of Safety Science and Technology, 32 Beiyuan Road, Beijing 100012, China
| | - Kai Wang
- School of Emergency Management and Safety Engineering, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China
| | - Hongwei Zhou
- School of Energy and Mining Engineering, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China
| | - Shirong Ge
- School of Artificial Intelligence, China University of Mining & Technology, D11 Xueyuan Road, Beijing 100083, China
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Xiang H, Zhen W, Ke Y, Xiang Y, Shuxin H, Yihao S, Bin L. Experimental Study on the Diffusion Law of Coal-Based Solid Waste Slurry with Grouting Filling in the Gangue Voids of the Caving Zone. ACS OMEGA 2024; 9:264-275. [PMID: 38222508 PMCID: PMC10785311 DOI: 10.1021/acsomega.3c04519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/04/2023] [Indexed: 01/16/2024]
Abstract
Due to the concealment of the caving zone, it is difficult to detect and grasp the diffusion law of the slurry in the voids of the gangue pile. On the preparation of reasonable grouting filling materials, a large-scale three-dimensional gangue grouting filling test system has been established to detect the slurry pressure and resistivity inside the gangue pile and analyze the flow pattern of the slurry in the voids of the gangue pile. The research results show that the slump and bleeding rate of the filling slurry are significantly reduced with the increase of the fly ash content. The optimal ratio of fly ash, coal gangue, and gasification slag is 7:2:1, with a mass fraction of 72%. In the process of grouting, the internal pressure of the gangue pile can be divided into the initial stable stage, the step growth stage, and the pressure stability stage, and the change curve of the pressure sensor at the lower level is similar. The resistance value of the original broken gangue in the experiment is approximately 1600 Ω. Grouting filling forms a slurry-rock mixture, and its resistance continuously decreases with the stable injection of the slurry (minimum value 150 Ω). It is determined that the slurry near the grouting hole mainly diffuses longitudinally with a good void filling effect. The void channels of slurry diffusion are randomly distributed and have different shapes, which hinder slurry flow and diffusion. Slurry particles accumulate and settle at local small voids. Meanwhile, the surface of the gangue blocks is dry, and the slurry absorbs part of the water during diffusion, resulting in the increase of the slurry concentration and the weakening of the lateral diffusion ability. Secondary or multiple grouting can effectively fill the void of the broken gangue and further improve the filling effect.
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Affiliation(s)
- He Xiang
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
| | - Wei Zhen
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
| | - Yang Ke
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
| | - Yu Xiang
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
| | - He Shuxin
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
| | - Shen Yihao
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
| | - Liu Bin
- School
of Mining Engineering, Anhui University
of Science and Technology, Huainan, Anhui 232001, China
- Institute
of Energy, Hefei Comprehensive National
Science Center, Hefei 230031, China
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Shi P, Zhang J, Yan H, Zhou N, Zhu G, Zhao Y, Chen P. Mechanical properties evaluation of waste gangue-based cemented backfill materials based on an improved response surface model. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:3076-3089. [PMID: 38079042 DOI: 10.1007/s11356-023-31368-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/30/2023] [Indexed: 01/18/2024]
Abstract
Traditional mining methods damage the cultivated land and produce gangue waste that often contaminates the environment. Yet, these problems can be mitigated by transforming the waste into gangue-based cemented backfill material (GCBM), whose mechanical properties are crucial for surface protection. Therefore, in this study, an intelligent model based on laboratory tests was developed to evaluate the GCBM's mechanical properties. The strength tests and polynomial response surface model (PRSM) were used to analyze the non-linear correlation between the influencing factors and the uniaxial compressive strength (UCS). Meanwhile, the importance of multidimensional factors was analyzed by the mean impact value, revealing that concentration and gangue proportion are the most sensitive factors. In addition, an intelligent response surface model (IRSM) based on support vector regression model was constructed by enhancing an optimization algorithm with chaotic mapping and adaptive methods. The performance of the traditional PRSM and the novel IRSM was compared, and the IRSM was validated. The IRSM can predict UCS more efficiently and effectively than the traditional PRSM under high-dimensional factors, with R2 of 0.96 and MBE of 0.05. This indicated that the IRSM has the potential to promote coal mine waste reduction and environmental protection.
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Affiliation(s)
- Peitao Shi
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China
| | - Jixiong Zhang
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China
| | - Hao Yan
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China.
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China.
| | - Nan Zhou
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China
| | - Gaolei Zhu
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China
| | - Yang Zhao
- School of Mines, China University of Mining and Technology, Xuzhou, 221116, China
- State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou, 221116, China
| | - Peng Chen
- Erdos Yutai Huasheng Resource Recycling Technology Co, Ordos, 017010, China
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Shi Z, Zhao H, Liang B, Sun W, Wang J, Fang S. Simulation test study on filling flow law of gangue slurry in goaf. Sci Rep 2023; 13:19117. [PMID: 37926708 PMCID: PMC10625934 DOI: 10.1038/s41598-023-45596-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/21/2023] [Indexed: 11/07/2023] Open
Abstract
The disposal and utilization of solid waste of coal gangue is one of the main problems in coal mining in China. Injecting coal gangue into goaf in the form of slurry can effectively solve the problems of ground stacking and environmental pollution prevention. In order to obtain the flow law of gangue slurry in the void of the accumulated rock in the goaf, a visualization simulation test device for gangue slurry permeation grouting in the goaf was independently designed. The flow and diffusion characteristics, flow and diffusion velocity changes, void pressure changes, and viscosity changes of three mass concentrations (76%, 78%, 80%) of gangue slurry in the void between caved rock blocks in goaf were studied by visual grouting simulation test. The results show that: (1) The seepage process of gangue slurry in the goaf simulation test is divided into three diffusion forms, namely radial diffusion, axial diffusion, and bidirectional diffusion. The three diffusion forms are interrelated and inseparable. (2) The initial flow velocity of the slurry with different concentrations is different under the same permeation grouting pressure, and the higher the slurry concentration, the smaller the initial flow velocity of the slurry. The velocity of the slurry has a nonlinear relationship with the diffusion distance of the slurry. (3) With the permeation and diffusion of slurry, pressure sensors at different positions are subjected to pressure from bottom to top and enter the pressure boost stage, gradually forming stress peaks. When the slurry exceeds the position of the pressure sensor, the pressure on the pressure sensor is weakened and begins to enter the pressure relief stage, and the stress decline trend gradually becomes gentle with time. (4) The water loss effect occurs during slurry flow interaction with rock mass, resulting in slurry viscosity increasing. The viscosity of the slurry affects the difference in the amount of viscosity change. The research results can provide a certain theoretical basis for the goaf gangue slurry filling project.
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Affiliation(s)
- Zhanshan Shi
- School of Mining, Liaoning Technical University, Fuxin, 123000, China.
- Liaoning Academy of Mineral Resources Development and Utilization Technical and Equipment Research Institute, Liaoning Technical University, Fuxin, 123000, China.
| | - Hanwei Zhao
- School of Mining, Liaoning Technical University, Fuxin, 123000, China
| | - Bing Liang
- School of Mechanics and Engineering, Liaoning Technical University, Fuxin, 123000, China
| | - Weiji Sun
- School of Mechanics and Engineering, Liaoning Technical University, Fuxin, 123000, China
| | - Jian Wang
- School of Mechanics and Engineering, Liaoning Technical University, Fuxin, 123000, China
| | - Shengjie Fang
- School of Mining, Liaoning Technical University, Fuxin, 123000, China
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Li W, Yue L, Liu Y, Li S, Ma L, Wang J. Study on mechanical properties of coal gangue and fly ash mixture as backfill material based on fractal characteristics. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:111936-111946. [PMID: 37821737 DOI: 10.1007/s11356-023-30221-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 09/27/2023] [Indexed: 10/13/2023]
Abstract
Backfill mining can effectively alleviate the problems of surface collapse and ecological water pollution, in which the mechanical properties of backfill materials, including coal gangue and coal fly ash, have a decisive role in the effect of filling mining. In this study, we analyze the permeability characteristics of coal gangue filler through a set of homemade percolation test systems and introduce fractal characteristics to investigate the key factors affecting percolation in complex pores of broken coal gangue. The results indicate that the fractal dimensions of crushed coal gangue particles show an increasing trend with increasing axial loading and that the variation range is from 2.15647 to 2.58933. The coal fly ash concentration has a positive relationship with the acceleration factor. The permeability of crushed coal gangue follows a hierarchical distribution law and the permeability changes in the magnitude range of 10-11 ~ 10-9 m2. The fractal dimension is inversely related to the permeability of crushed coal gangue. The experimental results show that the coal gangue will be further crushed and that adding a certain concentration of coal fly ash can achieve a better water barrier, which provides theoretical support and engineering significance for the stability analysis of geological engineering and backfill mining technology.
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Affiliation(s)
- Wei Li
- School of Mechanical Engineering, Jiangsu Normal University, Jiangsu, China
| | - Lei Yue
- School of Mechanical Engineering, Jiangsu Normal University, Jiangsu, China
| | - Yu Liu
- School of Mechanical Engineering, Jiangsu Normal University, Jiangsu, China.
- State Key Laboratory of Coal Resources and Safety Mining, China University of Mining and Technology, Jiangsu, China.
| | - Shuncai Li
- School of Mechanical Engineering, Jiangsu Normal University, Jiangsu, China
- State Key Laboratory of Coal Resources and Safety Mining, China University of Mining and Technology, Jiangsu, China
| | - Liqiang Ma
- School of Mines, China University of Mining and Technology, Jiangsu, China
| | - Jintao Wang
- School of Mechanical Engineering, Jiangsu Normal University, Jiangsu, China
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Guo Y, Zhao Y, Feng G. Creep and strength characteristics of cemented gangue backfill under coupling effect of load and acid corrosion. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:97281-97297. [PMID: 37589844 DOI: 10.1007/s11356-023-28931-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Cemented gangue backfill technology is beneficial to the reuse of solid waste and sustainable economic development. However, mine water has a great impact on the strength and deformation of cemented gangue backfill (CGB). In this study, the CGB specimens under load were placed in simulated acid mine water (H2SO4 solution). The changes in deformation, resistivity, and ultrasonic pulse velocity (UPV) of CGB were monitored. On the 360th day, the stress-strain curve and acoustic emission (AE) energy of the specimen during loading were recorded. The degradation mechanism of CGB was discussed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the deformation of CGB increased with time. The effect of H2SO4 solution concentration on the deformation was different in the early and late stages. Applying an 80% stress-strength ratio (SSR) reduced the strength and increased the deformation. The UPV and resistivity had different characteristics at different corrosion ages, which could be used for long-term stability monitoring of CGB. The CGB showed the strongest AE energy characteristics near the peak stress. The AE energy decreased with the increase of pH value in the pore compaction stage, and the AE activity of the CGB under 80% SSR was much greater than that of the CGB under 40% SSR. The erosion of the H2SO4 solution on the CGB was inhibited by applying a small load. Excessive load aggravated the erosion deterioration of CGB due to initial plastic damage. The research results can provide a reference for the durability design of CGB.
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Affiliation(s)
- Yuxia Guo
- College of Mining Technology, Taiyuan University of Technology, Taiyuan, 030024, China
- Shanxi Province Coal-Based Resources Green and High-Efficiency Development Engineering Center, Taiyuan, 030024, China
- Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan, 030024, China
| | - Yonghui Zhao
- College of Mining Technology, Taiyuan University of Technology, Taiyuan, 030024, China.
- Shanxi Province Coal-Based Resources Green and High-Efficiency Development Engineering Center, Taiyuan, 030024, China.
| | - Guorui Feng
- College of Mining Technology, Taiyuan University of Technology, Taiyuan, 030024, China
- Shanxi Province Coal-Based Resources Green and High-Efficiency Development Engineering Center, Taiyuan, 030024, China
- Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan, 030024, China
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9
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Cheng A, Zhou Y, Chen G, Huang S, Ye Z. Acoustic emission characteristics and fracture mechanism of cemented tailings backfill under uniaxial compression: experimental and numerical study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:55143-55157. [PMID: 36890404 DOI: 10.1007/s11356-023-26298-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
Cemented tailings backfill (CTB) is the most cost-effective and environmentally friendly method to recycle tailings for filling mining. It is of great significance to study the fracture mechanism of CTB for safe mining. In this study, three cylindrical CTB samples with a cement-tailings ratio of 1:4 and a mass fraction of 72% were prepared. An acoustic emission (AE) test under uniaxial compression (UC) with WAW-300 microcomputer electro-hydraulic servo universal testing machine and DS2 series full information AE signal analyzer was carried out to discuss the AE characteristics of CTB, such as hits, energy, peak frequency, and AF-RA. Combined with particle flow and moment tensor theory, a meso AE model of CTB was constructed to reveal the fracture mechanism of CTB. The results show that (1) the AE law of CTB under UC has periodic characteristics, which can be divided into the rising stage, stable stage, booming stage, and active stage. (2) The peak frequency of the AE signal is mainly focused on three frequency bands. The ultra-high frequency AE signal may be the precursor information for CTB failure. (3) The low frequency band AE signals represent shear crack, while the medium and high frequency band AE signals represent tension crack. The shear crack initially decreases and then increases, and the tension crack is the opposite. (4) The fracture types of the AE source are divided into tension crack, mixed crack, and shear crack. The tension crack is dominant, while a larger magnitude AE source is frequently shear crack. The results can provide a basis for the stability monitoring and fracture prediction of CTB.
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Affiliation(s)
- Aiping Cheng
- School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, China.
- State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization, Jinchang, 737100, Gansu, China.
| | - Yafeng Zhou
- School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, China
| | - Guoju Chen
- State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization, Jinchang, 737100, Gansu, China
| | - Shibing Huang
- School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, China
| | - Zuyang Ye
- School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, China
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10
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Zhao K, Zhao K, Yan Y, Yang J, Wu J, Lai Y, Liu L, Zeng X. Influence of different fibers on compressive toughness and damage of early age cemented tailings backfill. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:37449-37461. [PMID: 36574120 DOI: 10.1007/s11356-022-24830-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 12/14/2022] [Indexed: 06/18/2023]
Abstract
For improving the utilization rate of tailings and the safety of cemented tailings backfill (CTB) as earthwork materials, the influence of three types of fibers (e.g., glass, polyacrylonitrile and mixture fibers of both) on compressive toughness and damage of early age CTB was studied. An equation for quantitative analysis of compressive toughness of fiber-reinforced CTB was established. An uniaxial compression test was carried out to monitor the damage acoustic emission (AE) activities of CTB during the loading process. Then, the microstructure of CTB after uniaxial compression test was observed by scanning electron microscope (SEM). The results indicated that mixed fiber has the most comprehensive reinforcement effect on compressive toughness and peak load of CTB. Three fibers inhibited the crack development rate of CTB, glass fiber mainly absorbed axial strain energy of CTB before peak load, while polyacrylonitrile fiber mainly absorbed fracture energy generated during the crack development of CTB after peak load, mixed fiber combined their advantages. The AE activities of three fiber-reinforced CTB samples are much stronger than those of non-reinforced CTB samples in the loading process, and these are no "quiet period" of AE activities. Three fibers all improved the durability of CTB in the damage process, and the damage process of mixed fiber-reinforced CTB is the most stable and showed an approximate linear growth trend. Polyacrylonitrile fiber has a strong resistance to crack after the peak load of CTB because of its ellipsoid part on the surface. As a result, this study can provide a theoretical reference for construction units to use fiber-reinforced CTB for engineering applications and filling work.
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Affiliation(s)
- Kang Zhao
- School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi, 341000, China.
- Solids Waste and Chemicals Management Center, Ministry of Ecology and Environment, Beijing, 100029, China.
| | - Kangqi Zhao
- School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi, 341000, China
| | - Yajing Yan
- Solids Waste and Chemicals Management Center, Ministry of Ecology and Environment, Beijing, 100029, China
| | - Jian Yang
- School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi, 341000, China
| | - Jun Wu
- School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi, 341000, China
| | - Yanming Lai
- School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi, 341000, China
| | - Lang Liu
- College of Energy Engineering, Xi'an University of Science and Technology, Xi'an 710054, China
| | - Xiankun Zeng
- China Nerin Engineering Co., Ltd, Nanchang Jiangxi, 330002, China
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11
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Wu P, Zhao G, Li Y. Research and development trend of green mining: a bibliometric analysis. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:23398-23410. [PMID: 36322348 DOI: 10.1007/s11356-022-23830-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
As green development has become a mainstream feature of modern development, green technology has become an inevitable trend in the development of mining technology, and related research on the subject continues to accumulate. Based on the bibliometric analysis of the green mining (GM) research from 2001 to 2020, we try to capture GM research and development trends from the perspective of global green development. The results show that the growth rate of GM research is much higher than that of conventional mining research, and the research results are growing rapidly. A visual collaborative network was created to identify the main research countries and author distribution and explore the most contributed journals. The research themes in GM show an evolution from sustainability theory to the application of green technologies in mines to the establishment of long-term mechanisms and policy regulation. The keyword co-occurrence results show that the current GM research covers the whole life cycle of mines. Soil, waste disposal, and recycling are long-standing research hotspots, and the most relevant articles are about resource recycling. Based on the keyword co-occurrence results, the proportion of restoration and management research has rapidly increased from 7.3 to 28.9%. Ecological restoration, reclamation and monitoring, remote sensing, and other technologies are more closely integrated usually accompanied by research related to evaluation and management. With the evolution of the theme, the research on GM is becoming more and more comprehensive. It reflects an extremely strong interdisciplinary and cross-disciplinary character.
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Affiliation(s)
- Pan Wu
- School of Resources & Safety Engineering, Central South University, Changsha, 410083, China
| | - Guoyan Zhao
- School of Resources & Safety Engineering, Central South University, Changsha, 410083, China.
| | - Yang Li
- School of Resources & Safety Engineering, Central South University, Changsha, 410083, China
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Zhao X, Yang K, He X, Wei Z, Yu X, Zhang J. Study on Mix Proportion Optimization and Microstructure of Coal-Based Solid Waste (CSW) Backfill Material Based on Multi-Objective Decision-Making Model. MATERIALS (BASEL, SWITZERLAND) 2022; 15:ma15238464. [PMID: 36499959 PMCID: PMC9740858 DOI: 10.3390/ma15238464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 06/01/2023]
Abstract
The preparation of underground-backfill material from CSW can be used for large-scale disposal of solid waste. The proportion of backfill material plays an important role in transportation and backfilling effect, and the mix-proportion optimization of backfill material is essentially a multi-factor and multi-objective optimization problem. In this paper, to obtain the mix proportion of backfill materials with optimal comprehensive-evaluation indexes, and suitable for the engineering application, the fluidity and strength of backfill material, mainly composed of coal gangue(CG), fly ash (FA), flue gas desulfurization gypsum (FGD gypsum), and gasification coarse slag (GCS), were tested by single-factor transformation method, and the effects of various solid wastes on the slump-flow, bleeding rate and early strength of backfill material were analyzed. The optimal mix proportion of CSW with the slump-flow, bleeding rate, and 3-day and 7-day strengths as the evaluation indicators is FA: GCS: FGD gypsum: CG = 25%:25%:25%:25%, according to the multi-objective decision model. Furthermore, the comprehensive evaluation index that meets the requirements of mine backfilling is obtained by changing the ordinary portland cement (OPC) content, that is, the optimal OPC content is 10% of the total solid waste, and the mass concentration is 78%. Finally, the pore structure, micromorphology, and composition of the backfill material with the optimal mix proportion were studied by Mercury Intrusion Porosimetry (MIP), X-ray Diffraction (XRD), and Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS). The research results provide a good reference for the field application of CSW for underground backfilling.
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Affiliation(s)
- Xinyuan Zhao
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China
| | - Ke Yang
- Institute of Energy, Hefei Comprehensive National Science Center, Hefei 230031, China
| | - Xiang He
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China
| | - Zhen Wei
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China
| | - Xiang Yu
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China
| | - Jiqiang Zhang
- State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China
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13
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Ran H, Guo Y, Feng G, Li C. Failure properties and stability monitoring of strip and column cemented gangue backfill bodies under uniaxial compression in constructional backfill mining. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:51411-51426. [PMID: 35244851 DOI: 10.1007/s11356-022-19336-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
The strip and column cemented gangue backfill bodies (CGBBs) are the main supporting components in the design of constructional backfill mining for coal mining, which determines the stability of goaf. Previous researches have mostly focused on the mechanical properties of column CGBB, but the mechanical properties of strip CGBB are still unclear. Herein, the uniaxial compression experiments for strip and column CGBBs were conducted to compare the failure properties. The acoustic emission (AE) and two types of resistivity monitoring were used to monitor the damage evolution. The effect of the length-height ratio on the mechanical characteristic of strip CGBB was analyzed by discrete element simulation. The results show that the strength and peak strain of strip CGBB under uniaxial compression is higher than those of column CGBB and the strip CGBB shows better ductility. The stress of column CGBB decreases significantly faster than that of strip CGBB at the post-peak stage. The strength and ductility of strip CGBB increase with the increase of length-height ratio. The strip CGBB is destroyed from both ends to the middle under uniaxial compression, and the core bearing area is reduced correspondingly. The AE signal evolution of CGBBs under uniaxial compression before the peak stress contains three stages, and the AE signals of strip CGBB at the peak stress will not rise sharply compared with column CGBB. The resistivity monitoring effect of the horizontally symmetrical conductive mesh is better than that of the axial. The horizontal resistivity increases gradually with the increase of stress under uniaxial compression, and increases sharply at the peak stress, and then drops after the peak stress. The damage constitutive models and the stability monitoring models of the CGBBs are established based on the experimental results. This work would be instructive for the design and stability monitoring of CGBB.
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Affiliation(s)
- Hongyu Ran
- College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
- Research Center of Green Mining Engineering Technology in Shanxi Province, Taiyuan, 030024, China
| | - Yuxia Guo
- College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
- Research Center of Green Mining Engineering Technology in Shanxi Province, Taiyuan, 030024, China.
| | - Guorui Feng
- College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
- Research Center of Green Mining Engineering Technology in Shanxi Province, Taiyuan, 030024, China
| | - Chunqing Li
- School of Engineering, RMIT University, Melbourne, 3001, Australia
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Expansion Properties of Cemented Foam Backfill Utilizing Coal Gangue and Fly Ash. MINERALS 2022. [DOI: 10.3390/min12060763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cemented backfill (CB) utilizing coal gangue (CG) and fly ash (FA) is widely applied in coal mines. However, the bleeding and shrinkage of CB leads to insufficient contact with surrounding rock, which is not beneficial for controlling roof subsidence and even stope stability. Herein, a cemented foam backfill (CFB) formulation is demonstrated, employing hydrogen dioxide (H2O2) as a chemical foaming agent. The cement and FA show noticeable inhibiting effects on volume expansion due to the network formed by their hydrates. Moderately lower cement, FA, and solid concentration are beneficial to improve volume increment and prolong expanding duration. A foaming coefficient (k) is proposed in theory to evaluate the foaming efficiency. The kem values, determined by volume evolution experiments of CFB slurries, provide a calculation basis for the needed dosage of H2O2 solution targeting specific volume increment. CFB specimens with expanding ratios of 21%~103% and densities of 994~592 kg/cm3 were prepared, with an actual foaming coefficient of 52.40 cm3/g and uniaxial compressive strength (UCS) of 0.32~0.55 MPa. The mass of H2O2 solution was 1.9%~11.3% of cement and 0.29%~1.67% of total solid materials by weight. The UCS decline compared to CB was attributed to rich pores observed by CT and carbonation indicated by X-ray diffraction (XRD).
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Abstract
With the development of science and technology, backfill technology has made continuous progress, and the traditional backfill method is no longer suitable for various complicated practical engineering situations. Therefore, researchers in the field of backfill mining have gradually shifted their research focus to the study of high-concentration backfill, and Chinese researchers are no exception. In order to solve the problems caused by the traditional backfill method, China began to vigorously develop high-concentration backfill in recent years, and achieved a lot of results. In this paper, some important achievements made by Chinese researchers on high-concentration backfill in recent years are reviewed; it also presents a summary report of the latest research results from several key laboratories across China. Therefore, this paper reviews the development progress of high-concentration backfill China has made, of which the main contents include: (1) research progress of the high-concentration backfill theory in China; and (2) research progress of high-concentration backfill equipment in China. Finally, we claim that this paper serves just as a guide to start a conversation, and we hope many more experts and scholars will be interested and engage in the research of this field.
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