Study on Rheological Characteristics of Uncemented Coal Gangue-Fly Ash Backfill (UCGFB) Slurry Based on Fractal Theory

Jin, Junyu; Yang, Faguang; Gu, Chengjin; Zhou, Yibo; Wang, Xiaolong

doi:10.1155/2022/7634951

“…Therefore, paste-filling technology has become a hot spot of research and application in recent years: Zhang Qinli and Wang Xinmin, et al studied the movement form of the filling paste in the pipeline gravity conveying system and the settlement law of solid particles of filling aggregate and theoretically analyzed the feasibility of pipeline gravity conveying with coal gangue as the major aggregate [4]. Yang Jiaqiang and Zhou Yao, et al studied the effect of different particle sizes and water-gangue ratios on the rheological properties of coal gangue paste by testing the rheological properties, fluidity and flow time of coal gangue paste and discussed the change rules of the rheological parameters, fluidity and flow time [5][6][7]. Zhu Lei and Huang Yucheng, et al have carried out research and an engineering application for the pipe-filling technology of the paste made of coal gangue as an aggregate [8][9][10][11][12], conducted simulation and experimental research on the flow and diffusion laws of the gangue-filling paste in the caving zone above the underground work and discussed the underground treatment and fluidized filling technology in the inbreak area [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Rheological Properties of Coal Gangue Slurry Based on Response Surface Methodology

Sun

¹

,

Wu

²

2023

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To handle the gangue well and control the settlement of the surface, as well as to reduce the risk of water bleeding, settlement and even blockage and pipe breaking of the gangue slurry in the process of conveying, the rheological characteristics of the slurry should be studied. The rheological properties of slurry with different concentrations prepared from gangue samples of the Ningtiaota coal mine were tested, and the correlation between the rheological characteristics of the coal gangue filling slurry and three factors, namely the gangue mass fraction, grain gradation and standing time, were studied by a single factor method and response surface methodology. The results show that the fitting curve of the Herschel–Bulkley model is mostly linear, that is, the shear stress of coal gangue paste increases as a function of the shear rate. Therefore, these two concentrations are too small to form a stable network structure to wrap large particles and can easily cause pipe blockage. The yield shear stress and plastic viscosity show an exponential increase with the increasing mass fraction. The shear stress and apparent viscosity of the pastes with mass fractions of 60% and 65%, respectively, increase significantly after 20, 40 and 60 min of standing. According to the comprehensive test results and the response surface, the optimization method is as follows: mass fraction of 72%; aggregate grading for 4.75~1.18 mm particle size is 30%, for 1.18~0.425 mm particle size is 40%, for 0.425~0.075 mm particle size is 10%, for less than 0.075 mm particle size is 20%; with different standing times, the yield shear stress of slurry ranges from 103.02 to 131.645 Pa; and the plastic viscosity ranges from 0.54 to 0.64 Pa.s. With the increase of the standing time, the slurry settlement is relatively small, and is a more ideal gangue slurry proportion.

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“…Sun et al [21] studied the effects of gangue mass fraction, particle gradation and standing time on the rheological properties of gangue lling slurry, and con rmed that the characteristics of coal gangue slurry belong to Bingham uid. Based on fractal theory, Jin et al [22] analyzed the particle size distribution of coal gangue-y ash mixture under different mixing ratios, and studied the effects of gradation and concentration on the rheological parameters of coal gangue-y ash slurry. Wang et al [23] obtained the spatial distribution expression of viscosity decay rate considering the in uence of water-cement ratio through a one-dimensional visual grouting test, and derived the Bingham uid column permeability grouting theoretical formula considering the spatial decay of viscosity.…”

Section: Introductionmentioning

confidence: 99%

Simulation test study on filling flow law of gangue slurry in goaf

Liang,

Zhao,

Shi

et al. 2023

Preprint

0

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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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“…Sun et al 22 studied the effects of gangue mass fraction, particle gradation and standing time on the rheological properties of gangue filling slurry, and confirmed that the characteristics of coal gangue slurry belong to Bingham fluid. Jin et al 23 , 24 analyzed the particle size distribution of coal gangue-fly ash mixture under different mixing ratios, and studied the effects of gradation and concentration on the rheological parameters of coal gangue-fly ash slurry. Wang et al 25 obtained the spatial distribution expression of viscosity decay rate considering the influence of water-cement ratio through a one-dimensional visual grouting test, and derived the Bingham fluid column permeability grouting theoretical formula considering the spatial decay of viscosity.…”

Section: Introductionmentioning

confidence: 99%

Simulation test study on filling flow law of gangue slurry in goaf

Shi,

Zhao,

Liang

et al. 2023

Sci Rep

3

0

View full text Add to dashboard Cite

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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Study on Rheological Characteristics of Uncemented Coal Gangue-Fly Ash Backfill (UCGFB) Slurry Based on Fractal Theory

Cited by 5 publications

References 24 publications

Experimental Study on Rheological Properties of Coal Gangue Slurry Based on Response Surface Methodology

Experimental Study on Rheological Properties of Coal Gangue Slurry Based on Response Surface Methodology

Simulation test study on filling flow law of gangue slurry in goaf

Simulation test study on filling flow law of gangue slurry in goaf

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