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Yang H, Qian Z, Yue B, Xie Z. Effects of Cement Dosage, Curing Time, and Water Dosage on the Strength of Cement-Stabilized Aeolian Sand Based on Macroscopic and Microscopic Tests. MATERIALS (BASEL, SWITZERLAND) 2024; 17:3946. [PMID: 39203124 PMCID: PMC11355670 DOI: 10.3390/ma17163946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 07/20/2024] [Accepted: 08/06/2024] [Indexed: 09/03/2024]
Abstract
Aeolian sand is distributed worldwide, exhibiting poor grading, low cohesion, and loose structure. Infrastructure construction in desert areas sometimes requires stabilization of the sand, with cement as the primary curing agent. This study first employed orthogonal experiments to evaluate critical factors, e.g., curing time, cement dosage, and water dosage, affecting the unconfined compressive strength (UCS) of the aeolian sand stabilized with cement (ASC). Each of the aforementioned factors were set at five levels, namely curing time (7, 14, 28, 60, and 90 days), cement dosage (3%, 5%, 7%, 9%, and 11%), and water dosage (3%, 6%, 9%, 12%, and 15%), respectively. The water and cement dosages were percentages of the mass of the natural aeolian sand. The results indicated that the sensitivity of the influencing factors on the UCS of ASC was cement dosage, curing time, and water dosage in descending order. The UCS of ASC positively correlated with curing time and cement dosage, while it first increased and then decreased with the water dosage increase. The optimal conditions were 90 days' curing time, 11% cement dosage, and 9% water dosage. The microscopic analyses of ASC using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) revealed that hydration products enhanced strength by bonding loose particles and filling pores, thereby improving compaction. The quantity and compactness of hydration products in the aeolian-cement reaction system increased with the increases in cement dosage and curing time, and low water dosage inhibited the hydration reaction. This study can provide insights into the stabilization mechanism of aeolian sand, aiding infrastructure development in desert regions.
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Affiliation(s)
- Heng Yang
- School of Engineering and Technology, China University of Geosciences, Beijing 100083, China; (H.Y.); (B.Y.); (Z.X.)
| | - Zengzhen Qian
- School of Engineering and Technology, China University of Geosciences, Beijing 100083, China; (H.Y.); (B.Y.); (Z.X.)
| | - Bing Yue
- School of Engineering and Technology, China University of Geosciences, Beijing 100083, China; (H.Y.); (B.Y.); (Z.X.)
- Key Laboratory on Deep Geo-Drilling Technology, Ministry of Natural Resources, Beijing 100083, China
| | - Zilu Xie
- School of Engineering and Technology, China University of Geosciences, Beijing 100083, China; (H.Y.); (B.Y.); (Z.X.)
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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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Zhang S, Zhang X, Bai H, Wang K. Resource utilization of stone waste and loess to prepare grouting materials. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 354:120452. [PMID: 38401503 DOI: 10.1016/j.jenvman.2024.120452] [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: 10/09/2023] [Revised: 01/12/2024] [Accepted: 02/20/2024] [Indexed: 02/26/2024]
Abstract
Loess, a terrestrial clastic sediment, is formed essentially by the accumulation of wind-blown dust, while stone waste (SW) is an industrial waste produced during stone machining. Utilising loess and SW to prepare environmentally-friendly supplementary cementitious materials can not only address environmental issues caused by solid waste landfills but also meet the demand of reinforcement of coal-seam floor aquifer for grouting materials. In this paper, the effects of the loess/SW mass ratio and calcination temperature on the transformation of calcined products are investigated and their pozzolanic activities are evaluated. The workability, environmental impact and cost of grouting materials based on cement and calcined products are also assessed. Experimental results reveal that higher temperatures favour the formation of free lime and periclase, which tend to be involved in solid-state reactions. Higher temperature and loess/SW mass ratio strengthens the diffraction peaks of dodecalcium hepta-aluminate (C12A7), dicalcium ferrite (C2F) and dicalcium silicate (C2S). The clay minerals in loess become completely dehydroxylated before 825 °C, generating amorphous SiO2 and Al2O3. Covalent Si-O bonds are interrupted and that disordered silicate networks are generated in the calcined products, which is confirmed by the increased strength of the Si29 resonance region at -60 ppm to -80 ppm. Although co-calcined loess and SW contain the most four-fold aluminium at 950 °C, recrystallisation depresses the pozzolanic activity. Hence, the loess/SW sample designated LS2-825 exhibits the better hydration activity. Additionally, grouting materials composed of cement and LS2-825 exhibit good setting times, fluidity, strength and a low carbon footprint in practical engineering applications, and they also provide the additional benefit of being cost effective.
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Affiliation(s)
- Shiyu Zhang
- School of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Xiaoqiang Zhang
- School of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
| | - Hao Bai
- School of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Kai Wang
- School of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
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Liu Y, Yuan N, Wang S, Wang D. Evaluation of the applicability of gasification coarse slag as a fine aggregate in controlled low-strength material: preparation, performance, and environmental effect. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:14927-14937. [PMID: 38286927 DOI: 10.1007/s11356-024-32074-x] [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: 08/24/2023] [Accepted: 01/15/2024] [Indexed: 01/31/2024]
Abstract
Gasification slag (GS) is rich in SiO2, Al2O3, and Fe2O3, and has excellent particle size gradation, which has the potential to be employed as an aggregate in the field of controlled low-strength material (CLSM). Nevertheless, the large-scale application of GS as the fine aggregate for the preparation of CLSM has been scarcely investigated. In the present work, the applicability of replacing part of coal gangue (CG) with gasification coarse slag (GCS) as fine aggregate for the preparation of CLSM was investigated. The results revealed that using GCS as a fine aggregate improved the flowability of CLSM, and increasing the GCS content from 0 to 50 wt% improved the flowability from 250.0 to 280.0 mm. The 28-day compressive strength of all CLSM conformed to the requirements of ACI Committee 229. Compared to the Blank group, the 7- and 28-day compressive strength of the CLSM increased by 23.07% and 26.80%, respectively, at a GCS content of 50 wt%. The increase in compressive strength was mainly due to the pore-filling and hydration-promoting effect of the GCS, which made the structure denser. The dense structure reduced the expansion rate, absorption, and porosity rate of CLSM and increased the wet density. The optimal process parameter was the addition of 10 wt% of GCS. The results of heavy metal ion leaching showed that the optimal sample GS10 leached all heavy metal ions in much less than the limit values of GB 8978-1996 and GB 5085.3-2007. The results will provide new ideas and technical approaches for the large-scale application of GCS as the fine aggregate in CLSM.
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Affiliation(s)
- Yun Liu
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Ding No.11 Xueyuan Road, Haidian District, Beijing, 100083, China
| | - Ning Yuan
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Ding No.11 Xueyuan Road, Haidian District, Beijing, 100083, China.
| | - Shanhu Wang
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Ding No.11 Xueyuan Road, Haidian District, Beijing, 100083, China
| | - Dongmin Wang
- School of Chemical and Environmental Engineering, China University of Mining and Technology, Ding No.11 Xueyuan Road, Haidian District, Beijing, 100083, China
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Guo Z, Qiu J, Kirichek A, Zhou H, Liu C, Yang L. Recycling waste tyre polymer for production of fibre reinforced cemented tailings backfill in green mining. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168320. [PMID: 37949142 DOI: 10.1016/j.scitotenv.2023.168320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/21/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023]
Abstract
The increasing amount of solid waste, e.g., waste tyres from car industry and tailings from mine operations, causes substantial environmental and societal issues. The recycled tyre polymer fibre (RTPF) reinforced cemented tailings backfill (CTB) is a kind of composite that can treat waste tyres and tailings simultaneously and realize green mining, but its engineering properties have not been well understood. In this study, the rheology (i.e., static and dynamic yield stress, and structural build-up), strength (i.e., uniaxial and triaxial compressive, splitting tensile and flexural strengths), microstructure, and life cycle of RTPF reinforced CTB are comprehensively evaluated. For comparison, the engineering performance of the commonly used polypropylene fibre (PPF) reinforced CTB in mines is tested. The experimental results demonstrate that incorporating 0.6 wt% RTPF into CTB can achieve comparable fluidity and strength to the CTB reinforced with 0.3 wt% PPF at reduced cost and improved sustainability. A strength enhancement approach for RTPF reinforced CTB is also developed by adjusting the viscosity of suspending CTB before the addition of RTPF. With this approach, the splitting tensile strength increases by 68 %. The results obtained from this study pave the way for promoting the recycling of abandoned waste tyres and the safe design of backfill structures in mines.
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Affiliation(s)
- Zhenbang Guo
- School of Resource and Civil Engineering, Northeastern University, Shenyang, China; Science and Technology Innovation Center of Smart Water and Resource Environment, Northeastern University, Shenyang 110819, China; Section of Rivers, Ports, Waterways and Dredging Engineering, Department of Hydraulic Engineering, Faculty of Civil Engineering & Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| | - Jingping Qiu
- School of Resource and Civil Engineering, Northeastern University, Shenyang, China; Science and Technology Innovation Center of Smart Water and Resource Environment, Northeastern University, Shenyang 110819, China
| | - Alex Kirichek
- Section of Rivers, Ports, Waterways and Dredging Engineering, Department of Hydraulic Engineering, Faculty of Civil Engineering & Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
| | - Hao Zhou
- Xingshan Iron Mine, Mining Corporation, Shougang Group Co., Ltd., Qian'an, Hebei 064404, China
| | - Chen Liu
- Department of Materials and Environment (Microlab), Faculty of Civil Engineering and Geoscience, Delft University of Technology, Delft, the Netherlands
| | - Lei Yang
- Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, MD 21218, USA.
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Xie G, Suo Y, Liu L, Yang P, Qu H, Zhang C. Pore characteristics of sulfate-activated coal gasification slag cement paste backfill for mining. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:114920-114935. [PMID: 37878178 DOI: 10.1007/s11356-023-30554-0] [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: 07/19/2022] [Accepted: 10/15/2023] [Indexed: 10/26/2023]
Abstract
With the mass production of coal-based solid waste, coal mine filling can effectively consume it. The coal gasification slag is modified and prepared as coal mine filling material to meet the relevant technical requirements, which can realize the recycling of coal mine → coal chemical industry → coal mine. In this paper, in order to explore the evolution law of the mechanical properties and pore structure characteristics of the modified coal gasification slag-cement cemented paste backfill (MCGS-CPB) prepared by sodium sulfate excitation coal gasification slag, a combined macro-meso-micro testing method is used. MCGS-CPB with different sodium sulfate contents (1~5%) were prepared and tested for uniaxial compressive strength (UCS), mercury intrusion (MIP) and microscopic tests. The results show that sodium sulfate has a significant effect on the UCS and pore structure characteristics of MCGS-CPB. The mechanical properties and pore structure characteristics of MCGS-CPB were best when sodium sulfate was doped at 3%; the mechanical properties and pore structure characteristics of MCGS-CPB were deteriorated when the addition of sodium sulfate is higher than 3%. On the meso-scale, when sodium sulfate was doped with 3%, the more harmful pores of MCGS-CPB gradually changed into harmless, less harmful, and harmful pores, and the macroscopic mechanical properties were gradually improved; when the addition of sodium sulfate is higher than 3%, the harmless, less harmful, and harmful pores of MCGS-CPB gradually changed into more harmful pores, and the macroscopic mechanical properties were deteriorated. On a microscopic scale, sodium sulfate can cause MCGS-CPB to form hydration products with expansion properties. The presence of a reasonable amount of sodium sulfate in the pores of MCGS-CPB is beneficial to the development of mechanical properties. However, excessive presence will lead to the formation of expansion stress, gradual formation of micro-expansion cracks, and deteriorate the macroscopic mechanical properties. Hence, the volcanic ash activity of coal gasification slag excited by external addition of sodium sulfate should not exceed 3%. This study provides a reference value for application ratio of sodium sulfate-stimulated MCGS-CPB used in coal mine filling design.
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Affiliation(s)
- Geng Xie
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China
- State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China
| | - Yonglu Suo
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi'an, 710054, China
| | - Lang Liu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
- Research Center for Functional Backfill Technology in Mine, Xi'an, 710054, China.
- State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China.
| | - Pan Yang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China
- State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China
| | - Huisheng Qu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China
- State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China
| | - Caixin Zhang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China
- State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China, Xi'an, 710054, China
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Wang S, Yang R, Li Y, Xu B, Lu B. Single-factor analysis and interaction terms on the mechanical and microscopic properties of cemented aeolian sand backfill. INTERNATIONAL JOURNAL OF MINERALS, METALLURGY AND MATERIALS 2023; 30:1584-1595. [DOI: 10.1007/s12613-022-2574-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 09/01/2023]
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Ruan S, Liu L, Zhu M, Shao C, Xie L, Hou D. Application of desulfurization gypsum as activator for modified magnesium slag-fly ash cemented paste backfill material. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 869:161631. [PMID: 36657671 DOI: 10.1016/j.scitotenv.2023.161631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
Recycling industrial solid waste for mine backfill is one of the best ways to achieve green production in multiple industries. In this paper, the desulfurization gypsum (DG) as an activator is combined with the modified magnesium slag-fly ash cementitious paste backfill (MFPB) technology for the co-disposal of solid waste and goaf treatment, and the influence of DG on the performance of MFPB was comprehensively analyzed through rheological properties, mechanical properties, durability, microscopic analysis and environmental characteristics experiments. The results show that the fresh MFPB mortar conforms to the Herschel-Bulkley model at different maximum shear rate (γ̇max) conditions. When the γ̇max is 100 s-1, the mortar exhibits shear-thickening properties. The apparent viscosity, yield stress and static yield stress of mortar decreased first and then increased with the increase of DG content, and all had the minimum value when DG was 2.5 %. The thixotropy of the mortar was significantly increased with the addition of DG, and the change in thixotropy was significantly correlated with the difference between the two yield stresses. Both the rheological and mini-slump results demonstrate that DG can improve the flowability of MFPB mortars. In addition, the UCS of D0 under steam curing and standard water curing conditions for 28 d were 4.342 MPa and 2.827 MPa, and the sample containing DG were 6.109-8.241 MPa and 6.669-9.492 MPa, respectively. The addition of DG not only improves the strength of MFPB, but also improves the durability of MFPB. Microscopic analysis (XRD, SEM, and TG-DTG) indicated that this was mainly because DG promoted the hydration reaction of the MMS-FA system and accelerated the generation of C-S(A)-H and AFt. Finally, in the results of in situ leaching based on durability and leaching based on standard HJ 557, all the indexes of MFPB meet the standard of class III groundwater in GB/T 14848-2017, and it has an effective stabilization/solidification effect on heavy metals (As, Cu, Ni, Ba, Zn and Mo, etc.). To sum up, the collaboration of DG and MFPB technology can not only efficiently clean and utilize a variety of solid wastes (MMS, FA and DG), but also greatly improve the performance of MFPB to promote its application.
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Affiliation(s)
- Shishan Ruan
- Energy School, Xi'an University of Science and Technology, Xi'an 710054, China.
| | - Lang Liu
- Energy School, Xi'an University of Science and Technology, Xi'an 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an 710054, China.
| | - Mengbo Zhu
- Energy School, Xi'an University of Science and Technology, Xi'an 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an 710054, China.
| | - Chengcheng Shao
- Energy School, Xi'an University of Science and Technology, Xi'an 710054, China.
| | - Lei Xie
- Energy School, Xi'an University of Science and Technology, Xi'an 710054, China.
| | - Dongzhuang Hou
- Xi'an Fill Green Innovation Mining Technology Co., Ltd., Xi'an 710054, China.
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Tang R, Zhao B, Tian C, Xu B, Li L, Shao X, Ren W. Preliminary Study of Preheated Decarburized Activated Coal Gangue-Based Cemented Paste Backfill Material. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16062354. [PMID: 36984235 PMCID: PMC10052327 DOI: 10.3390/ma16062354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 05/27/2023]
Abstract
This study proposes a novel idea of the use of coal gangue (CG) activation and preheated decarburized activated coal CG-based cemented paste backfill material (PCCPB) to realize green mining. PCCPB was prepared with preheated decarburized coal CG (PCG), FA, activator, low-dose cement, and water. This idea realized scale disposal and resource utilization of coal CG solid waste. Decarbonization and activation of CG crushed the material to less than 8 mm by preheated combustion technology at a combustion temperature of 900 °C and a decarbonization activation time of 4 min. The mechanism of the effect of different Na2SO4 dosages on the performance of PCCPB was investigated using comprehensive tests (including mechanical property tests, microscopic tests, and leaching toxicity tests). The results show that the uniaxial compressive strength (UCS) of C-S2, C-S3, and C-S4 can meet the requirements of backfill mining, among which the UCS of C-S3 with a curing time of 3 d and 28 d were 0.545 MPa and 4.312 MPa, respectively. Na2SO4 excites PCCPB at different curing time, and the UCS of PCCPB increases and then decreases with the increase in Na2SO4 dosage, and 3% of Na2SO4 had the best excitation effect on the late strength (28 d) of PCCPB. All groups' (control and CS1-CS4 groups) leachate heavy metal ions met the requirements of groundwater class III standard, and PCCPB had a positive effect on the stabilization/coagulation of heavy metal ions (Mn, Zn, As, Cd, Hg, Pb, Cr, Ba, Se, Mo, and Co). Finally, the microstructure of PCCPB was analyzed using FTIR, TG/DTG, XRD, and SEM. The research is of great significance to promote the resource utilization of coal CG residual carbon and realize the sustainable consumption of coal CG activation on a large scale.
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Affiliation(s)
- Renlong Tang
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Bingchao Zhao
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Chuang Tian
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
| | - Baowa Xu
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
| | - Longqing Li
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Xiaoping Shao
- Energy School, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Wuang Ren
- School of Architecture and Civil Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
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Wang S, Li Y, Yang R, Xu B, Lu B. Rheological behavior with time dependence and fresh slurry liquidity of cemented aeolian sand backfill based on response surface method. CONSTRUCTION AND BUILDING MATERIALS 2023; 371:130768. [DOI: 10.1016/j.conbuildmat.2023.130768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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11
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Yang P, Liu L, Suo Y, Qu H, Xie G, Zhang C, Deng S, Lv Y. Basic characteristics of magnesium-coal slag solid waste backfill material: Part I. preliminary study on flow, mechanics, hydration and leaching characteristics. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 329:117016. [PMID: 36586328 DOI: 10.1016/j.jenvman.2022.117016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/06/2022] [Accepted: 12/10/2022] [Indexed: 06/17/2023]
Abstract
The environmental damage caused by surface subsidence and coal-based solid waste (CBSW) is a common problem in the process of coal mining. Backfill mining can control the mining-induced subsidence and solve the problem of bulk solid waste storage. In the present work, a magnesium-coal slag solid waste backfill material (MCB) with modified magnesium slag (MS) as binder and CBSW (fly ash (FA), flue gas desulfurization gypsum (FDG) and coal gasification slag (CGS)) as supplementary cementitious material/aggregate was proposed to meet the needs of coal mining in Northern Shaanxi, China, to realize the comprehensive treatment of goaf and CBSW. The results show that: (1) The rheological curve of the fresh MCB slurry is highly consistent with the Herschel-Bulkley (H-B) model, and its fluidity meets the basic requirements of mine backfill pumping. With the addition of FDG and MS, the yield stress, apparent viscosity and thixotropy of MCB slurry increase, while the pseudoplastic index and slump decrease. (2) The strength of MCB develops slowly in the early stage (0∼14 days) and increases rapidly in the later stage (14∼90 days). Except for the ratio of M20F1 and FDG = 0%, the strength of samples at other ratios (at 28 days) is between 6.06∼11.68 MPa, which meets the strength requirement of 6 MPa for coal mine backfill. The addition of MS and appropriate amount of FDG is beneficial to the development of strength. In contrast, MS exhibits a significant improvement in early strength, and FDG has a significant improvement in late-age strength. (3) Corresponding to the compressive strength, the hydration products C-S(A)-H and AFt of MCB are less in the early stage and greatly increased in the later stage. The active substance in FA/CGS will undergo pozzolanic reaction with the MS hydration product CH. The addition of FDG and MS can promote the reaction and increase the amount of hydration product, but in contrast, the promotion effect of FDG is more significant. (4) The amount of heavy metal leaching of MCB meets the requirements of national standards. The hardened MCB has a solidification/stabilization effect on heavy metal elements, which can significantly reduce the amount of heavy metal leaching. The results imply that MCB is a safe, reliable, and eco-friendly solid waste backfill material, and its application is conducive to the coordinated development of coal resource mining and environmental protection.
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Affiliation(s)
- Pan Yang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Lang Liu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an, 710054, China.
| | - Yonglu Suo
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an, 710054, China.
| | - Huisheng Qu
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Geng Xie
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Caixin Zhang
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Shunchun Deng
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
| | - Yin Lv
- Energy School, Xi'an University of Science and Technology, Xi'an, 710054, China.
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Fang K, Wang D, Gu Y. Utilization of Gasification Coarse Slag Powder as Cement Partial Replacement: Hydration Kinetics Characteristics, Microstructure and Hardening Properties. MATERIALS (BASEL, SWITZERLAND) 2023; 16:1922. [PMID: 36903037 PMCID: PMC10003838 DOI: 10.3390/ma16051922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Coal gasification coarse slag (GFS) is a byproduct of coal gasification technology, which contains abundant amorphous aluminosilicate minerals. GFS has low carbon content, and its ground powder has potential pozzolanic activity, which can be used as a supplementary cementitious material (SCM) for cement. Herein, GFS-blended cement was studied in terms of ion dissolution characteristics, initial hydration kinetics, hydration reaction process, microstructure evolution process, and the development of the mechanical strength of their paste and mortar. Enhanced alkalinity and elevated temperature could increase the pozzolanic activity of GFS powder. The specific surface area of GFS powder and its content did not change the reaction mechanism of cement. The hydration process was divided into three stages: crystal nucleation and growth (NG), phase boundary reaction (I), and diffusion reaction (D). A higher specific surface area of the GFS powder could improve the chemical kinetic process of the cement system. The degree of reaction of GFS powder and blended cement had a positive correlation. A low GFS powder content (10%) with a high specific surface area (463 m2/kg) showed the best activation in cement as well as improving the late mechanical properties of cement. The results show GFS powder with low carbon content has the application value as SCM.
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Hao Y, Song X, Huang Y, Zhang B, Dong Z, Wang H. Mesoscopic damage evolution and acoustic emission characteristics of cemented paste backfill under different loading rates. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:90686-90702. [PMID: 35870070 DOI: 10.1007/s11356-022-22154-1] [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: 04/26/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
The cemented paste backfill (CPB) has a significant loading rate (LR) effect. The damage evolution process of CPB is closely related to the characteristics of acoustic emission (AE). This paper analyzes the damage evolution law of the filling body under different loading rates using indoor test and numerical simulations. We introduce the moment tensor theory to simulate the AE characteristics of the whole process of filling loading and explore the LR effect of the backfill with the help of the energy conservation. The results indicate the following: (1) when LR increases from 0.1 to 2 mm/min, the UCS of the backfill first increases and then decreases, contributing to the occurance of the critical LR. (2) There are no microcracks occurred in the backfill at the initial stage of loading, and the microcracks increase slowly, which is not obviously affected by LR. After the peak value, the microcracks in backfill expand and propagat rapidly to form mesoscopic cracks. (3) The mesoscopic AE events based on the moment tensor theory are in good agreement with the laboratory tests results, which can be divided into the initial period, quiet period, slow raising period, rapid raising period, and rapid falling period. (4) The temporal and spatial distribution characteristics of AE are consistent with the evolution law of microcracks. There are fewer AE events before the peak value, and AE events increase significantly and frequently with large magnitude events after the peak value. AE events dense zone and AE events with larger magnitude increase under higher LR. (5) Besides, the boundary energy and dissipation energy also gradually increased; at the same time, the strain energy first increased and then decreased. The results can provide a reference for understanding the damage evolution characteristics of backfill by different LR and AE mesoscopic simulation.
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Affiliation(s)
- Yuxin Hao
- School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Xuepeng Song
- School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China.
| | - Yucheng Huang
- School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Bao Zhang
- School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
- Technical and Economic Research Institute of National Energy Group, Beijing, 102211, China
| | - Zilin Dong
- School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China
| | - Hao Wang
- Zhengzhou University of Science and Technology, Zhengzhou, 450064, China
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Tao M, Lu D, Shi Y, Wu C. Utilization and life cycle assessment of low activity solid waste as cementitious materials: A case study of titanium slag and granulated blast furnace slag. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 849:157797. [PMID: 35932851 DOI: 10.1016/j.scitotenv.2022.157797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/24/2022] [Accepted: 07/30/2022] [Indexed: 06/15/2023]
Abstract
The dumping of cement production and industrial solid waste can cause severe environmental impact. In order to reduce the environmental impact of cement production and reasonably dispose of solid waste, a new type of cementing material was developed using industrial solid waste as raw materials. It solves the problem that low activity solid waste is difficult to reuse and makes up for the less research, which considered both preparation and environmental evaluation. The orthogonal tests of cement mortar strength as well as life cycle assessment were carried out. The results from variance and range analyses of the orthogonal tests revealed that the fraction of solid waste mainly affected the compressive strength of the solid waste cement mortar, and its specific surface area primarily influenced the flexural strength. After curing for 28 days, the compressive and flexural strength values of the developed cementing material were 40.6 MPa and 8.6 MPa, respectively. The results of life cycle impact assessment indicated that the developed solid waste cement had more environmental advantages than ordinary cement in 18 midpoints environmental impact types, and could diminish environmental impact by 16.1 % on the whole. The solid waste cement has achieved great environmental gains in the human toxicity, natural land transformation, metal depletion, climate change and other environmental impact categories. In addition, the clinker calcination, transportation and material mining were identified as critical processes responsible for the human toxicity, natural land transformation and metal depletion. Through sensitivity and uncertainty analyses, the development of the solid waste cement was proved to be the most effective method to decrease the environmental impact of cement. Finally, the methods of further reducing the environmental impact of cement were proposed.
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Affiliation(s)
- Ming Tao
- School of Resources and Safety Engineering, Central South University, Changsha, China
| | - Daoming Lu
- School of Resources and Safety Engineering, Central South University, Changsha, China
| | - Ying Shi
- School of Resources and Safety Engineering, Central South University, Changsha, China.
| | - Chengqing Wu
- School of Civil and Environmental Engineering, University of Technology Sydney, Australia
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15
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Qu J, Zhang J, Li H, Li S, Shi D, Chang R, Wu W, Zhu G, Yang C, Wang C. Occurrence, leaching behavior, and detoxification of heavy metal Cr in coal gasification slag. Chin J Chem Eng 2022. [DOI: 10.1016/j.cjche.2022.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Zhu M, Xie G, Liu L, Yang P, Qu H, Zhang C. Influence of Mechanical Grinding on Particle Characteristics of Coal Gasification Slag. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6033. [PMID: 36079414 PMCID: PMC9457477 DOI: 10.3390/ma15176033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 06/15/2023]
Abstract
Based on the test results of laser particle size analyzer, specific surface area analyzer and infrared spectrometer, the grinding kinetics of coal gasification slag (CGS) was systematically described by using Divas-Aliavden grinding kinetics, Rosin-Rammler-Bennet (RRB) distribution model and particle size fractal theory. The influence of grinding time and particle group of CGS on the strength activity index of mortar was studied by using the strength activity index of mortar and grey correlation analysis. The results show that the particles are gradually refined before mechanical grinding of CGS for 75 min. When the mechanical grinding time is greater than 75 min, the "agglomeration phenomenon" of fine CGS particles led to the decrease in various properties. Divas-Aliavden grinding kinetics, the RRB model and fractal dimension can characterize the change of CGS particle size in the grinding process quantitatively. The strength activity index of CGS at different curing ages is positively correlated with grinding time, and the influence on the later strength activity index is the most obvious. The relationship between CGS particle size distribution and strength activity index were probed using grey correlation analysis. The CGS particle groups with the particle size of 20~30 μm and 10~20 μm have the greatest impact on the early and late strength activity index, respectively. Therefore, the optimal grinding time of CGS as auxiliary cementing material is 75 min, considering factors, such as economy and performance, and the specific surface area (SSA) is 4.4874 m2·g-1.
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Affiliation(s)
- Mengbo Zhu
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Geng Xie
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
| | - Lang Liu
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
- Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi’an 710054, China
| | - Pan Yang
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
| | - Huisheng Qu
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
| | - Caixin Zhang
- College of Energy Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
- Research Center for Functional Backfill Technology in Mine, Xi’an University of Science and Technology, Xi’an 710054, China
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Mechanical Properties, Durability and Leaching Toxicity of Cement-Stabilized Macadam Incorporating Reclaimed Clay Bricks as Fine Aggregate. SUSTAINABILITY 2022. [DOI: 10.3390/su14148432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The utilization of reclaimed clay brick (RCB) from construction and demolition (C&D) waste is an extremely troublesome problem, which is beneficial and necessary for environmental protection and resource conservation. The objective of this study is to evaluate the mechanical properties, durability and environmental impact of cement-stabilized macadam (CSM) incorporating RCB. The physical and chemical properties of RCB were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) technologies. RCB exhibited a porous surface micro-morphology, high water absorption and pozzolanic activity. The higher RCB substitution ratio resulted in a lower unconfined compressive strength of CSM. Meanwhile, the higher the RCB substitution ratio was, the larger the 90 d indirect tensile strength of CSM at the late curing period. The RCB substitution ratio within 50% was beneficial for the freeze-thaw resistance of CSM. Additionally, RCB had a smaller aggregate size, causing a negative influence on the anti-scouring property of CSM. CSM incorporating RCB had an overall increasing accumulative water loss rate, and average coefficients of dry shrinkage and temperature shrinkage, except that 20% RCB substitution ratio resulted in an excellent dry shrinkage property. Based on the chemical analysis of EDTA-2Na, the pozzolanic RCB reacted mainly at later curing to form the crystal structure, enhancing the interfacial transition zone. Additionally, the leaching solutions could meet the identification requirements for extraction toxicity, surface water and groundwater referring to Chinese standards. Utilizing RCB in road engineering as the substitute for natural aggregate would be a promising step forward to sustainable development and green construction.
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