The multiscale micro-nano pores in coal can result in the ultra-low permeability of coal,which restricts the efficiency of gas extraction.It is difficult for the conventional seepage-enhancement measures to affect the...The multiscale micro-nano pores in coal can result in the ultra-low permeability of coal,which restricts the efficiency of gas extraction.It is difficult for the conventional seepage-enhancement measures to affect the nanoscale pores within the coal matrix.Thermal stimulation can reach deep into the micro-nano pores within coal matrix to improve the permeability.Therefore,it is important to study the diffusivity and permeability of the multiscale micro-nano pores at different temperatures.In this study,the experiments of diffusion-seepage measured by the methods of GRI(Gas Research Institution)and steady-state were conducted using a cylindrical coal at different temperatures and pressures.The experimental results show that the apparent diffusion coefficient of cylindrical coal is not constant but variable dynamically;and the classical diffusion model fails to describe the full-time process of gas flow accurately.On this basis,a model of multiscale dynamic apparent diffusion-seepage that can accurately describe the full-time flow process was proposed.As is observed,the apparent permeability attenuates dynamically with time without stress loading,and the initial apparent permeability and the attenuation coefficient increase monotonically with the rise of temperature.Under the stress constraint,the steady-state permeability increases after a decrease as the temperature rises,displaying a“U-shaped”pattern.Without stress constraint,the increasing temperature causes the exterior multiscale pores to expand outward by different degrees so as to increase permeability,while the interior micro-nano pores show three inward and outward expansion mechanisms.Under stress constraint,at low temperature and high effective stress,the increasing temperature causes pores to expand inward and the permeability decreases accordingly.When temperature continues to increase,coal expands outward because the effective stress is counteracted by the thermal stress,leading to an increase in permeability.This study is of significance for thermal gas extraction engineering.展开更多
The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect o...The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect of the first mining on the lateral abutment pressure distribution and evolution in wide pillars,an in-situ experiment,theoretical analysis and numerical simulation were performed.First,the field monitoring of lateral abutment pressure was conducted from the perspective of time and space in the Chahasu Coal Mine,Huangling No.2 Coal Mine and Lingdong Coal Mine during the first mining.Based on the field monitoring stress,a theoretical model was proposed to reveal the lateral abutment pressure distribution.The methodology was demonstrated through a case study.Aiming at the distribution mechanism,a numerical experiment was conducted through the finite-discrete element method(FDEM).Last,field observations of borehole fractures were performed to further study the damage distribution.In addition,two types of lateral abutment pressure evolution with mining advance were discussed.Suggestions on the stress monitoring layout were proposed as well.The results could provide foundations for strata control and disaster prevention in wide pillars in underground coal mines.展开更多
Waste fried oil was studied to prepare three different types of detergent such as soap,liquid soap and soap powder via saponification process.The preparation conditions of soap base were optimized by orthogonal experi...Waste fried oil was studied to prepare three different types of detergent such as soap,liquid soap and soap powder via saponification process.The preparation conditions of soap base were optimized by orthogonal experiment.The specific preparation processes included waste fried oil treatment,orange peel extract preparation,saponification,demoulding and drying.Results showed that the optimal con-ditions for saponification were as follows:ratio of pure waste fried oil to coconut oil=6∶4,alkali liquor(NaOH)mass fraction 30%,saponification temperature 70℃,orange peel extract concentration 15%.The mature soap was then used to make liquid soap and soap powder by surfactant(sodium dodecylbenzene sulfonate,coconut diethanol amide)addition,followed by grinding.The prepared detergent conforms to the production standard of strong decontamination ability,possesses stable performance,is gentle to skin and non-toxic.展开更多
Bauxite is one of the main raw materials in the alumina industry.Fine high-sulfur bauxite flotation desulfurization is a great challenge presently.This study aims to synthesize nanoparticle collectors(NPCs)by emulsion...Bauxite is one of the main raw materials in the alumina industry.Fine high-sulfur bauxite flotation desulfurization is a great challenge presently.This study aims to synthesize nanoparticle collectors(NPCs)by emulsion polymerization to improve the abovesaid flotation desulfurization process.The physicochemical properties of high-sulfur bauxite were analyzed,and the experimental conditions for the synthesis of NPCs were optimized.The interaction mechanism between NPCs and pyrite was studied via fundamental analyses including SEM(Scanning Electron Microscope),FT-IR(Fourier Transform Infrared spectoscopy),Zeta-potential,XPS(X-ray Photoelectron Spectroscopy),and wettability.Under the closed-circuit flotation flowsheet of"one roughing-two cleaning-three scavenging",aluminum concen-trate with a yield of 85.91%and sulfur content of 0.56%were obtained using a common collector.However,with the addition of the novel NPC,aluminum concentrate with a yield of 85.70%and sulfur content of 0.36%could be obtained by a simpler flowsheet of"one roughing-one cleaning-two scav-enging".The improvement in flotation performance is suggested to be contributed by the addition of spherical NPC,which induced a rougher and more hydrophobic pyrite surface.展开更多
In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock ...In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses.The reliability of the TDSC was verified by a linear bedding plane model and field monitoring.Generally,the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions:(1)the increase of the normal stiffness of the bedding plane,(2)the increase of the incident angle of the stress wave,(3)the decrease of the incident frequency of the stress wave,or(4)the growth of three ratios(the ratios of rock densities,elastic moduli,and the Poisson’s ratios)of rocks on either side of bedding planes.The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes,and the weakening effect increases with the growth of the three ratios.Besides,the TDSC decreases exponentially in the rock mass as propagation distance increases.In a field case,the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.展开更多
To improve the adaptability of fluidized beds for fine coal separation,a new type of liquid-solid fluidized bed was constructed,i.e.,the inflatable-inclined liquid-solid fluidized bed(IILSFB).A combination of simulati...To improve the adaptability of fluidized beds for fine coal separation,a new type of liquid-solid fluidized bed was constructed,i.e.,the inflatable-inclined liquid-solid fluidized bed(IILSFB).A combination of simulation analysis and separation experiments was used to analyze the fluidization characteristics and separation performance of the IILSFB.The results showed that there was upflow and downflow in the fluidized bed.The upflow was mainly composed of water flow,followed by light and heavy particles;on the other hand,the downflow was caused by the backflow of heavy particles that settled at the inclined section.In addition,the light particles that settled at the inclined section could return to the rising water flow under the action of secondary airflow.As the water velocity,separation time,and secondary gas velocity increased,the comprehensive separation efficiency of fine coal in the fluidized bed improved,while the value decreased as the feed quantity increased.This also indicated the order of importance for these four factors,i.e.,water velocity,separation time,feed quantity,and secondary gas velocity,on fluidisation.Furthermore,the comprehensive separation efficiency of 0.1-1 mm fine coal varied significantly with various factors,while that of∼0.1 mm and 1-3 mm fine coal was always at a low value.In the latter case,the classification process of the size fraction was significantly better than the separation process in the fluidized bed.Under optimal working conditions,an IILSFB was used to separate the fine coal(0.1-1 mm).The yield of clean coal was 37.95% with an ash content of 12.11%,and the possible error was 0.085 g/cm^(3),indicating that the IILSFB had good separation performance for 0.1-1 mm fine coal.展开更多
基金Doctoral Foundation of Henan Polytechnic University,Grant/Award Number:B2021-7Key Science and Technology Project of Henan Province,Grant/Award Number:222102320017+3 种基金State Key Laboratory Cultivation Base for Gas Geology and Gas Control(Henan Polytechnic University),Grant/Award Number:WS2021A06National Natural Science Foundation of China,Grant/Award Number:52174173Key Scientific Research Projects of Colleges and Universities in Henan Province,Grant/Award Number:22B620002Fundamental Research Funds for the Universities of Henan Province,Grant/Award Number:NSFRF180305。
文摘The multiscale micro-nano pores in coal can result in the ultra-low permeability of coal,which restricts the efficiency of gas extraction.It is difficult for the conventional seepage-enhancement measures to affect the nanoscale pores within the coal matrix.Thermal stimulation can reach deep into the micro-nano pores within coal matrix to improve the permeability.Therefore,it is important to study the diffusivity and permeability of the multiscale micro-nano pores at different temperatures.In this study,the experiments of diffusion-seepage measured by the methods of GRI(Gas Research Institution)and steady-state were conducted using a cylindrical coal at different temperatures and pressures.The experimental results show that the apparent diffusion coefficient of cylindrical coal is not constant but variable dynamically;and the classical diffusion model fails to describe the full-time process of gas flow accurately.On this basis,a model of multiscale dynamic apparent diffusion-seepage that can accurately describe the full-time flow process was proposed.As is observed,the apparent permeability attenuates dynamically with time without stress loading,and the initial apparent permeability and the attenuation coefficient increase monotonically with the rise of temperature.Under the stress constraint,the steady-state permeability increases after a decrease as the temperature rises,displaying a“U-shaped”pattern.Without stress constraint,the increasing temperature causes the exterior multiscale pores to expand outward by different degrees so as to increase permeability,while the interior micro-nano pores show three inward and outward expansion mechanisms.Under stress constraint,at low temperature and high effective stress,the increasing temperature causes pores to expand inward and the permeability decreases accordingly.When temperature continues to increase,coal expands outward because the effective stress is counteracted by the thermal stress,leading to an increase in permeability.This study is of significance for thermal gas extraction engineering.
基金We gratefully acknowledge financial support from the National Natural Science Foundation of China(NSFC)(No.51704097)Science Foundation of Henan Polytechnic University(No.J2021–2)+1 种基金Key Research and Development Program of Henan Province,China(No.202102310244)“Science and Technology to Help the Economy 2020”Key Project(No.SQ2020YFF0426364).
文摘The wide pillars are generally popular due to the high productivity and efficiency in Northwest China.The distribution of lateral abutment pressure in coal pillars is important for mining safety.To reveal the effect of the first mining on the lateral abutment pressure distribution and evolution in wide pillars,an in-situ experiment,theoretical analysis and numerical simulation were performed.First,the field monitoring of lateral abutment pressure was conducted from the perspective of time and space in the Chahasu Coal Mine,Huangling No.2 Coal Mine and Lingdong Coal Mine during the first mining.Based on the field monitoring stress,a theoretical model was proposed to reveal the lateral abutment pressure distribution.The methodology was demonstrated through a case study.Aiming at the distribution mechanism,a numerical experiment was conducted through the finite-discrete element method(FDEM).Last,field observations of borehole fractures were performed to further study the damage distribution.In addition,two types of lateral abutment pressure evolution with mining advance were discussed.Suggestions on the stress monitoring layout were proposed as well.The results could provide foundations for strata control and disaster prevention in wide pillars in underground coal mines.
基金supported by the Foundation for University Key Teacher by Henan Province(grant No.2020GGJS051)the Research Fund of Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources(Henan Polytechnic University)(grant No.KCF2213)+1 种基金College Students'Innovative Entrepreneurial Training Plan Program(grant No.202110460072,202210460063)the Henan Polytechnic University Science Fund for Distinguished Young Scholars(grant No.J2021-1).
文摘Waste fried oil was studied to prepare three different types of detergent such as soap,liquid soap and soap powder via saponification process.The preparation conditions of soap base were optimized by orthogonal experiment.The specific preparation processes included waste fried oil treatment,orange peel extract preparation,saponification,demoulding and drying.Results showed that the optimal con-ditions for saponification were as follows:ratio of pure waste fried oil to coconut oil=6∶4,alkali liquor(NaOH)mass fraction 30%,saponification temperature 70℃,orange peel extract concentration 15%.The mature soap was then used to make liquid soap and soap powder by surfactant(sodium dodecylbenzene sulfonate,coconut diethanol amide)addition,followed by grinding.The prepared detergent conforms to the production standard of strong decontamination ability,possesses stable performance,is gentle to skin and non-toxic.
基金supported by the Foundation for University Key Teacher by Henan Province(grant No.2020GGJS051)Henan Polytechnic University Science Fund for Distinguished Young Scholars(grant No.J2021-1)Foundation for University Key Teacher by Henan Polytechnic University(grant No.2017XQG-12).
文摘Bauxite is one of the main raw materials in the alumina industry.Fine high-sulfur bauxite flotation desulfurization is a great challenge presently.This study aims to synthesize nanoparticle collectors(NPCs)by emulsion polymerization to improve the abovesaid flotation desulfurization process.The physicochemical properties of high-sulfur bauxite were analyzed,and the experimental conditions for the synthesis of NPCs were optimized.The interaction mechanism between NPCs and pyrite was studied via fundamental analyses including SEM(Scanning Electron Microscope),FT-IR(Fourier Transform Infrared spectoscopy),Zeta-potential,XPS(X-ray Photoelectron Spectroscopy),and wettability.Under the closed-circuit flotation flowsheet of"one roughing-two cleaning-three scavenging",aluminum concen-trate with a yield of 85.91%and sulfur content of 0.56%were obtained using a common collector.However,with the addition of the novel NPC,aluminum concentrate with a yield of 85.70%and sulfur content of 0.36%could be obtained by a simpler flowsheet of"one roughing-one cleaning-two scav-enging".The improvement in flotation performance is suggested to be contributed by the addition of spherical NPC,which induced a rougher and more hydrophobic pyrite surface.
基金This work is supported by the National Natural Science Foundation of China(Nos.51804099 and U1704129)the Focus Research and Special Development for Scientific and Technological Project of Henan Province(No.202102310542)+1 种基金the Fundamental Research Funds for the Central Universities(No.2018ZDPY02ZDPY02)the research fund of State Key Laboratory of Coal Resources and Safe Mining,CUMT(SKLCRSM19KF011).
文摘In this study,the tomography of dynamic stress coefficient(TDSC)was established based on a mechanical model of stress wave propagation in bedding planes and a mathematical model of the stress wave attenuation in rock masses.The reliability of the TDSC was verified by a linear bedding plane model and field monitoring.Generally,the TDSC in the dynamic stress propagation of bedding planes increases with the following conditions:(1)the increase of the normal stiffness of the bedding plane,(2)the increase of the incident angle of the stress wave,(3)the decrease of the incident frequency of the stress wave,or(4)the growth of three ratios(the ratios of rock densities,elastic moduli,and the Poisson’s ratios)of rocks on either side of bedding planes.The additional stress weakens TDSC linearly and slowly during the stress wave propagation in bedding planes,and the weakening effect increases with the growth of the three ratios.Besides,the TDSC decreases exponentially in the rock mass as propagation distance increases.In a field case,the TDSC decreases significantly as vertical and horizontal distances increase and its wave range increases as vertical distance increases in the sedimentary rock layers.
基金the financial support by the National Natural Science Foundation of China(No.51774283,No.51904096,No.52004086)the research fund of Henan Key Laboratory for Green and Efficient Mining&Comprehensive Utilization of Mineral Resources(Henan Polytechnic University)(KCF202005)the research fund of Henan Key Laboratory of Coal Green Conversion(Henan Polytechnic University)(CGCF201906).
文摘To improve the adaptability of fluidized beds for fine coal separation,a new type of liquid-solid fluidized bed was constructed,i.e.,the inflatable-inclined liquid-solid fluidized bed(IILSFB).A combination of simulation analysis and separation experiments was used to analyze the fluidization characteristics and separation performance of the IILSFB.The results showed that there was upflow and downflow in the fluidized bed.The upflow was mainly composed of water flow,followed by light and heavy particles;on the other hand,the downflow was caused by the backflow of heavy particles that settled at the inclined section.In addition,the light particles that settled at the inclined section could return to the rising water flow under the action of secondary airflow.As the water velocity,separation time,and secondary gas velocity increased,the comprehensive separation efficiency of fine coal in the fluidized bed improved,while the value decreased as the feed quantity increased.This also indicated the order of importance for these four factors,i.e.,water velocity,separation time,feed quantity,and secondary gas velocity,on fluidisation.Furthermore,the comprehensive separation efficiency of 0.1-1 mm fine coal varied significantly with various factors,while that of∼0.1 mm and 1-3 mm fine coal was always at a low value.In the latter case,the classification process of the size fraction was significantly better than the separation process in the fluidized bed.Under optimal working conditions,an IILSFB was used to separate the fine coal(0.1-1 mm).The yield of clean coal was 37.95% with an ash content of 12.11%,and the possible error was 0.085 g/cm^(3),indicating that the IILSFB had good separation performance for 0.1-1 mm fine coal.