The Experts below are selected from a list of 8403 Experts worldwide ranked by ideXlab platform
Chuncai Zhou - One of the best experts on this subject based on the ideXlab platform.
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investigation on thermal and trace element characteristics during co combustion biomass with coal Gangue
Bioresource Technology, 2015Co-Authors: Guijian Liu, Chuncai Zhou, Ting Fang, Paul K S LamAbstract:Abstract The thermochemical behaviors during co-combustion of coal Gangue (CG), soybean stalk (SS), sawdust (SD) and their blends prepared at different ratios have been determined via thermogravimetric analysis. The simulate experiments in a fixed bed reactor were performed to investigate the partition behaviors of trace elements during co-combustion. The combustion profiles of biomass was more complicated than that of coal Gangue. Ignition property and thermal reactivity of coal Gangue could be enhanced by the addition of biomass. No interactions were observed between coal Gangue and biomass during co-combustion. The volatilization ratios of trace elements decrease with the increasing proportions of biomass in the blends during co-combustion. Based on the results of heating value, activation energy, base/acid ratio and gaseous pollutant emissions, the blending ratio of 20–30% biomass content is regarded as optimum composition for blending and could be applied directly at current combustion application with few modifications.
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thermochemical and trace element behavior of coal Gangue agricultural biomass and their blends during co combustion
Bioresource Technology, 2014Co-Authors: Guijian Liu, Chuncai Zhou, Siwei Cheng, Ting Fang, Paul K S LamAbstract:The thermal decomposition behavior of coal Gangue, peanut shell, wheat straw and their blends during combustion were determined via thermogravimetric analysis. The coal Gangue/agricultural biomass blends were prepared in four weight ratios and oxidized under dynamic conditions from room temperature to 1000 °C by various heating rates. Kinetic models were carried out to evaluate the thermal reactivity. The overall mass balance was performed to assess the partition behavior of coal Gangue, peanut shell and their blends during combustion in a fixed bed reactor. The decomposition processes of agricultural biomass included evaporation, release of volatile matter and combustion as well as char oxidation. The thermal reactivity of coal Gangue could be improved through the addition of agricultural biomass in suitable proportion and subsequent appropriate heating rate during combustion. In combination with the heating value and base/acid ratio limitations, a blending ratio of 30% agricultural biomass is conservatively selected as optimum blending.
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transformation behavior of mineral composition and trace elements during coal Gangue combustion
Fuel, 2012Co-Authors: Guijian Liu, Chuncai Zhou, Ting Fang, Zhicao Yan, Ruwei WangAbstract:Abstract The transformation behavior of mineral and trace elements during combustion of Chinese coal Gangue at varies temperatures were studied. The coal Gangue sample was placed at muffle roaster and heated up to 8-desired temperature points, from 500 °C to 1200 °C with 100 °C for each interval. The mineral compositions of coal Gangue and its combustion ash were determined by X-ray powder diffraction techniques (XRD). FTIR spectroscopy analysis was taken to determine coal Gangue and combustion ash functional group, phase transition characteristics and the variation in combustion. The concentration of trace element in coal Gangue and combustion ash was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Results show that the transformation behavior of mineral phase of coal Gangue mainly relies on the combustion temperature. The volatilize ratios of selected trace elements increase with increasing combustion temperature. Besides, 10 trace elements studied in the current study can be classified into two categories according to their volatilize tendencies: (a) Ni, Cu, Zn, Cd, Sn, Pb and As were vaporized at intermediate temperature and have high volatilize ratio; (b) V, Cr, and Co were relative non-volatile.
Jixiong Zhang - One of the best experts on this subject based on the ideXlab platform.
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reutilization of Gangue wastes in underground backfilling mining overburden aquifer protection
Chemosphere, 2021Co-Authors: Jixiong Zhang, Hongyu Duan, Yanli Huang, Qiang Sun, Nan ZhouAbstract:Gangue backfilling mining (GBM) can effectively alleviate the Gangue accumulation pollution and the overburden aquifer destruction. To efficiently evaluate the reutilization of Gangue wastes by GBM and its advantage in overburden aquifer protection, non-Darcy hydraulic properties and deformation behaviors of granular Gangues were studied through laboratorial, theoretical, and in-situ aspects. A series of compression and seepage tests on granular Gangues under the variable original grain size grade (GSG) and stress rate were conducted. Laboratorial testing results convince that, hydraulic properties (porosity and permeability) of the granular Gangue decline with the increasing original GSG and decreasing stress rate. The crushing ratio of the sample increases with the increase of original GSG and the decrease of stress rate. The fractal dimension reveals more obvious increases in the samples with the higher original GSGs and lower stress rates. The Kruger model (a classical theoretical model) was employed to predict the permeability evolution based on the porosity. However, the invalid pores in rocks would result in the model's underestimation. To this end, an improved model was established to predict the permeability evolution by the fractal dimension, and the improved Kruger model has better accuracy than the original one. Finally, according to the laboratorial testing and theoretical predicted results, friendly-environmental strategies for overburden aquifer protection were proposed. The effectiveness of these strategies was successfully verified by an in-situ application. It is concluded that the high filling stress, low Gangue original GSG, and low filling stress rate in GBM can effectively reduce the risk of overburden aquifer destruction.
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Prediction of compression and deformation behaviours of Gangue backfill materials under multi-factor coupling effects for strata control and pollution reduction.
Environmental Science and Pollution Research, 2020Co-Authors: Meng Guohao, Jixiong Zhang, Zhu Cunli, Qiang ZhangAbstract:Coal mining causes serious ecological and environmental damage. The crushed Gangue is backfilled into underground goaf, which not only inhibits mining-induced subsidence but also reduces accumulation of waste on the ground: however, the effects of backfilling with Gangue backfill materials in goaf are affected by a combination of multiple factors. To predict compression-induced deformation (CID) of Gangue backfill materials, key factors influencing compression and deformation characteristics of Gangue backfill materials in an underground confined space (lithology, particle size distribution, lateral stress and lateral loading times) were determined. Moreover, two key factors, namely, lithology and particle size distribution of Gangue backfill materials, were quantified. Based on orthogonal test design, the compression characteristics of Gangue backfill materials were measured under different stress levels and coupling effects of the four key factors by utilising a self-made bidirectional loading test system for bulk materials. Furthermore, through regression, the relationships of the four key factors and axial strain were determined as well as undetermined parameters in axial stress-axial strain equations and axial stress. Based on this, an equation for predicting stress-strain relationship during compression-induced deformation of Gangue backfill materials under multi-factor coupling effects was established. Comparison with the orthogonal test results shows that this equation can predict compression-induced deformation of Gangue backfill materials in goaf. This is beneficial to providing a basis for predicting strata movement and surface subsidence and guidance for designing backfilling process, thus protecting the surface environment.
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reutilisation of coal Gangue and fly ash as underground backfill materials for surface subsidence control
Journal of Cleaner Production, 2020Co-Authors: Jixiong Zhang, Nan ZhouAbstract:Abstract To address the environmental problems caused by solid waste while promoting the sustainable development of mines, Gangue and fly ash can be used as underground backfill materials to achieve the comprehensive utilisation of solid waste mining resources. We measured the compressive deformation characteristics of samples with different ratios of Gangue to fly ash and analysed their stress-strain relationship and associated changes in their porosities using a YAS-5000 servo testing machine and a homemade compression apparatus. Moreover, we revealed the mechanisms of deformation resistance of Gangue and fly ash from both a macro and meso perspective and determined that the optimal ratio of Gangue to fly ash is 0.35. In addition, taking the backfill face in Coal Mine as an example, mixed materials of Gangue and fly ash at a ratio of 1:0.35 were backfilled into a goaf. After mining of the working face, the surface only sank by 170 mm approximately. This method not only effectively disposes of solid wastes, i.e., Gangue and fly ash, on a large scale but also controls surface subsidence to protect adjacent buildings and structures. Therefore, the coordinated development of coal resource mining and environmental protection are realised.
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effects of particle sizes on compressive deformation and particle breakage of Gangue used for coal mine goaf backfill
Powder Technology, 2020Co-Authors: Jixiong Zhang, Yanli HuangAbstract:Abstract Broken Gangue from the collapsing roof of a longwall coal panel can be used as the backfilling material for goaf backfilling. The particle size gradation has important influence on the compressive deformation of the Gangue backfilling material and particle breakage. The compressive deformation of the Gangue backfilling materials at 4 different particle size grades is simulated by PFC3D in this paper. The law of the compressive deformation of the Gangue backfilling material, the particle cluster distribution and the variation of the Gangue block shape are analyzed. The microscopic mechanism of the compressive deformation of the Gangue backfilling material is investigated based on the force-chain distribution. The results indicate that when the Gangue backfilling material has a small particle size, the specimen has low porosity and a few amounts of the broken particles can fill the pores of the material. When the particles have relatively large sizes, the specimen has relatively high porosity and the broken particles are unable to completely fill the pores. The loading conditions of the particles can only be changed by the frame structure formed by the large particles. If the proportion of the particle size grade is reasonable, a frame structure forms due to the large particles and the small particles with various particle sizes can fill the pores of the backfilling material. This enhances the deformability of the Gangue and decreases the compressive deformation of the backfilling material. After backfilled into the goaf, the backfilling material bears the overburden pressure, which means the process of roof convergence is the process of compressive deformation of the backfill body. That is to say, the stiffer the backfilling material, the better the control effect. The importance of the reasonable proportion of the particle size grade is explained from the aspect of microscopic breakage of the particles, which provides a scientific basis for backfill mining.
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fractal characteristics of crushed particles of coal Gangue under compaction
Powder Technology, 2017Co-Authors: Jixiong Zhang, Zhan Liu, Nan ZhouAbstract:Abstract The surface morphology of compacted and crushed Gangue presents self-similarity and other fractal characteristics. This research constructed a fractal model for the particle size of compacted and crushed Gangue based on fractal theory and particle size distribution information. To investigate the fractal characteristics of compacted Gangue, compaction experiments were carried out under varied stresses and with different particle sizes. Results showed that the particle size distributions of crushed Gangue specimens with two distinct lithology exhibited fractal characteristics. Fractal dimension of each crushed specimen ranged from 0.352 to 2.654, with increase of stress, the particle size of each specimen tended to be distributed in a more dispersed fashion. Meanwhile, the fractal dimension increased with increased content of small particles, and tended to be a definite value. While the fractal dimension decreased with increased rock strength for the same initial particle size gradation and stress.
Nan Zhou - One of the best experts on this subject based on the ideXlab platform.
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reutilization of Gangue wastes in underground backfilling mining overburden aquifer protection
Chemosphere, 2021Co-Authors: Jixiong Zhang, Hongyu Duan, Yanli Huang, Qiang Sun, Nan ZhouAbstract:Gangue backfilling mining (GBM) can effectively alleviate the Gangue accumulation pollution and the overburden aquifer destruction. To efficiently evaluate the reutilization of Gangue wastes by GBM and its advantage in overburden aquifer protection, non-Darcy hydraulic properties and deformation behaviors of granular Gangues were studied through laboratorial, theoretical, and in-situ aspects. A series of compression and seepage tests on granular Gangues under the variable original grain size grade (GSG) and stress rate were conducted. Laboratorial testing results convince that, hydraulic properties (porosity and permeability) of the granular Gangue decline with the increasing original GSG and decreasing stress rate. The crushing ratio of the sample increases with the increase of original GSG and the decrease of stress rate. The fractal dimension reveals more obvious increases in the samples with the higher original GSGs and lower stress rates. The Kruger model (a classical theoretical model) was employed to predict the permeability evolution based on the porosity. However, the invalid pores in rocks would result in the model's underestimation. To this end, an improved model was established to predict the permeability evolution by the fractal dimension, and the improved Kruger model has better accuracy than the original one. Finally, according to the laboratorial testing and theoretical predicted results, friendly-environmental strategies for overburden aquifer protection were proposed. The effectiveness of these strategies was successfully verified by an in-situ application. It is concluded that the high filling stress, low Gangue original GSG, and low filling stress rate in GBM can effectively reduce the risk of overburden aquifer destruction.
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reutilisation of coal Gangue and fly ash as underground backfill materials for surface subsidence control
Journal of Cleaner Production, 2020Co-Authors: Jixiong Zhang, Nan ZhouAbstract:Abstract To address the environmental problems caused by solid waste while promoting the sustainable development of mines, Gangue and fly ash can be used as underground backfill materials to achieve the comprehensive utilisation of solid waste mining resources. We measured the compressive deformation characteristics of samples with different ratios of Gangue to fly ash and analysed their stress-strain relationship and associated changes in their porosities using a YAS-5000 servo testing machine and a homemade compression apparatus. Moreover, we revealed the mechanisms of deformation resistance of Gangue and fly ash from both a macro and meso perspective and determined that the optimal ratio of Gangue to fly ash is 0.35. In addition, taking the backfill face in Coal Mine as an example, mixed materials of Gangue and fly ash at a ratio of 1:0.35 were backfilled into a goaf. After mining of the working face, the surface only sank by 170 mm approximately. This method not only effectively disposes of solid wastes, i.e., Gangue and fly ash, on a large scale but also controls surface subsidence to protect adjacent buildings and structures. Therefore, the coordinated development of coal resource mining and environmental protection are realised.
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fractal characteristics of crushed particles of coal Gangue under compaction
Powder Technology, 2017Co-Authors: Jixiong Zhang, Zhan Liu, Nan ZhouAbstract:Abstract The surface morphology of compacted and crushed Gangue presents self-similarity and other fractal characteristics. This research constructed a fractal model for the particle size of compacted and crushed Gangue based on fractal theory and particle size distribution information. To investigate the fractal characteristics of compacted Gangue, compaction experiments were carried out under varied stresses and with different particle sizes. Results showed that the particle size distributions of crushed Gangue specimens with two distinct lithology exhibited fractal characteristics. Fractal dimension of each crushed specimen ranged from 0.352 to 2.654, with increase of stress, the particle size of each specimen tended to be distributed in a more dispersed fashion. Meanwhile, the fractal dimension increased with increased content of small particles, and tended to be a definite value. While the fractal dimension decreased with increased rock strength for the same initial particle size gradation and stress.
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compressive deformation and energy dissipation of crushed coal Gangue
Powder Technology, 2016Co-Authors: Nan Zhou, Xiaole Han, Jixiong ZhangAbstract:Abstract Crushed Gangue, an inhomogeneous and discontinuous medium, is accompanied with the absorption and dissipation of energy under compression. In order to study the compressive deformation and energy dissipation of Gangue in the loading process under conditions of different particle sizes, loading rates, and first-time stress loads, a SANS testing machine and steel cylinder were used to conduct experiments in this paper. The following conclusions were drawn from the investigation: 1) The Gangue underwent three separate stages of compressive deformation, which included rapid, slow, and stable; 2) The energy density of the Gangue increased nonlinearly as the strain increased, and the dissipated energy accounted for 10%, 20%, and 70% of the total energy, respectively, of the three compressive deformation stages; 3) Particle size and loading rate had significant effects on the deformation and energy dissipation of the Gangue. The smaller the particle size or loading rate were, the more energy was required to produce the same level of deformation; 4) When the second stress load was smaller than the first-time stress load, the strain of the Gangue increased approximately linearly. When the second stress load was greater, the strain of the Gangue showed a logarithmic increase with the stress. Furthermore, under a greater first-time stress load, the Gangue presented smaller strain under secondary compression, showed more resistance to deformation, and consumed more energy to produce the same deformation.
Guijian Liu - One of the best experts on this subject based on the ideXlab platform.
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investigation on thermal and trace element characteristics during co combustion biomass with coal Gangue
Bioresource Technology, 2015Co-Authors: Guijian Liu, Chuncai Zhou, Ting Fang, Paul K S LamAbstract:Abstract The thermochemical behaviors during co-combustion of coal Gangue (CG), soybean stalk (SS), sawdust (SD) and their blends prepared at different ratios have been determined via thermogravimetric analysis. The simulate experiments in a fixed bed reactor were performed to investigate the partition behaviors of trace elements during co-combustion. The combustion profiles of biomass was more complicated than that of coal Gangue. Ignition property and thermal reactivity of coal Gangue could be enhanced by the addition of biomass. No interactions were observed between coal Gangue and biomass during co-combustion. The volatilization ratios of trace elements decrease with the increasing proportions of biomass in the blends during co-combustion. Based on the results of heating value, activation energy, base/acid ratio and gaseous pollutant emissions, the blending ratio of 20–30% biomass content is regarded as optimum composition for blending and could be applied directly at current combustion application with few modifications.
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thermochemical and trace element behavior of coal Gangue agricultural biomass and their blends during co combustion
Bioresource Technology, 2014Co-Authors: Guijian Liu, Chuncai Zhou, Siwei Cheng, Ting Fang, Paul K S LamAbstract:The thermal decomposition behavior of coal Gangue, peanut shell, wheat straw and their blends during combustion were determined via thermogravimetric analysis. The coal Gangue/agricultural biomass blends were prepared in four weight ratios and oxidized under dynamic conditions from room temperature to 1000 °C by various heating rates. Kinetic models were carried out to evaluate the thermal reactivity. The overall mass balance was performed to assess the partition behavior of coal Gangue, peanut shell and their blends during combustion in a fixed bed reactor. The decomposition processes of agricultural biomass included evaporation, release of volatile matter and combustion as well as char oxidation. The thermal reactivity of coal Gangue could be improved through the addition of agricultural biomass in suitable proportion and subsequent appropriate heating rate during combustion. In combination with the heating value and base/acid ratio limitations, a blending ratio of 30% agricultural biomass is conservatively selected as optimum blending.
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transformation behavior of mineral composition and trace elements during coal Gangue combustion
Fuel, 2012Co-Authors: Guijian Liu, Chuncai Zhou, Ting Fang, Zhicao Yan, Ruwei WangAbstract:Abstract The transformation behavior of mineral and trace elements during combustion of Chinese coal Gangue at varies temperatures were studied. The coal Gangue sample was placed at muffle roaster and heated up to 8-desired temperature points, from 500 °C to 1200 °C with 100 °C for each interval. The mineral compositions of coal Gangue and its combustion ash were determined by X-ray powder diffraction techniques (XRD). FTIR spectroscopy analysis was taken to determine coal Gangue and combustion ash functional group, phase transition characteristics and the variation in combustion. The concentration of trace element in coal Gangue and combustion ash was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Results show that the transformation behavior of mineral phase of coal Gangue mainly relies on the combustion temperature. The volatilize ratios of selected trace elements increase with increasing combustion temperature. Besides, 10 trace elements studied in the current study can be classified into two categories according to their volatilize tendencies: (a) Ni, Cu, Zn, Cd, Sn, Pb and As were vaporized at intermediate temperature and have high volatilize ratio; (b) V, Cr, and Co were relative non-volatile.
Changlong Wang - One of the best experts on this subject based on the ideXlab platform.
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preparation and properties of autoclaved aerated concrete using coal Gangue and iron ore tailings
Construction and Building Materials, 2016Co-Authors: Changlong Wang, Siqi Zhang, Shuang Wang, Guosheng Gai, Weikang WangAbstract:Abstract In this paper a new type of autoclaved aerated concrete (ACC) was developed using coal Gangue (CGC) and iron ore tailings (ITOs). The material compositions, calcination temperatures of the coal Gangue, and the composition of the hydration products were analysed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The optimal thermal activation temperatures and the activation mechanisms of the calcined coal Gangue were also studied. The results indicated that the optimal calcination temperature of coal Gangue was approximately 600 °C. The bulk density and compressive strength of AAC samples were approximately 609 kg m −3 and 3.68 MPa, respectively, which passed the requirements of A3.5, B06 level of AAC sample regulated by GB/T 11969-2008. Before the autoclaving, the hydration products in ACC containing CGC and ITOs were tobermorite, hibschite, ettringite, and C–S–H gel; during the autoclaving, ettringite was decomposed and more tobermorite formed coupled with C–S–H gel and hibschite.
