Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble si...Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble size.For the same volume system,fewer bubbles result from a distribution of large-sized bubbles,and more bubbles result from a distribution of small-sized bubbles.In this research,fundamental two-phase frother characterization parameters were aimed to link with three-phase coal and talc flotation behavior.For this purpose,the effect of single and dual frother systems on inhibiting bubble coalescence was investigated with methyl isobutyl carbinol(MIBC),isooctanol(2 ethyl hexanol),pine oil,and Dowfroth 250.Based on the results of single frothers,isooctanol at the lowest critical coalescence concentration(CCC)value of 6×10^(−6) achieved the smallest bubbles with Sauter mean diameter of 0.80 mm.By blending Dowfroth 250 and pine oil,the bubbles size decreased significantly,reaching 0.45 mm.While the highest recoveries in coal flotation were obtained in single and frother blends where the bubbles size was measured as the smallest in two-phase system,and such a relationship was not found for talc flotation.展开更多
Aluminum foams were fabricated by melt-based route using ZrH2 as a foaming agent. The factors which affected the foaming of aluminum foams during casting process were investigated. The powdered zirconium hydride with ...Aluminum foams were fabricated by melt-based route using ZrH2 as a foaming agent. The factors which affected the foaming of aluminum foams during casting process were investigated. The powdered zirconium hydride with content of 0.6%-1.4% （mass fraction） was added to the molten pure aluminum and the foaming condition was controlled in a temperature range from 933 to 1 013 K, Ca amount of 1.5%-3.0% （mass fraction）, stirring time of 0.5-2.5 min and holding time of 1.5-4.0 min to obtain homogeneous aluminum foams. The fabricated aluminum foams were characterized by XRD, SEM and Image-pro plus. The mechanical properties of the aluminum foams with different relative density were tested. The result indicates that the foaming agent （ZrH2） is suitable for the preparation of small aperture aluminum foams with average pore diameter of 1 mm. Inter-metallic compounds and Al2O3 have effect on the melt viscosity. The aluminum foams experience linear elastic, platforms and densification process and had a higher efficiency of energy absorption.展开更多
A new method of testing frother performance was proposed. Four parameters were tested： maximum foam volume, foam half-life, gas-liquid ratio and mean foam rise velocity. Among them the former two parameters indicate ...A new method of testing frother performance was proposed. Four parameters were tested： maximum foam volume, foam half-life, gas-liquid ratio and mean foam rise velocity. Among them the former two parameters indicate frother＇s foaming ability and foam stability respectively, and the latter two indicate water carrying ability and foam viscosity, respectively. The performance of four frothers in a two-phase （solution-air） system was tested and batch flotation tests on a copper ore were carried out. By analyzing frother performance in a two-phase system and comparing with the flotation results, correlation between them was found. Higher-copper concentrate grade was obtained by frothers with weak water carrying ability and low foam viscosity. And frothers with strong foaming ability and stable foam tend to obtain higher copper recovery.展开更多
In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a wat...In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.展开更多
[Objective]The study was conducted to investigate the effects of shading treatments on growth of Asimina triloba （L） Dunal seedlings and provided the theoretical basis for seedling production. [Method]70 day-old A. ...[Objective]The study was conducted to investigate the effects of shading treatments on growth of Asimina triloba （L） Dunal seedlings and provided the theoretical basis for seedling production. [Method]70 day-old A. triloba seedlings had similar stem diameter and plant height and good growth vigour were taken as tested materials in 2005. 4 light gradient treatments which were the natural light with 100% light intensity, one-layer, two-layer and three-layer black shading network with the light transmittance rate of 50%, 25% and 12.5% were set up to study the effects of different shading treatments on growth of A. triloba. [ Result] With the shading treatments of one-layer and two-layer net, the plants of A. triloba seedlings grew rapidly. As the intensity of illumination decreased, the cetents of chlorophyll a （ Chl. a）, chlorophyll b （ Chl. b） and total chlorophyll increased at first and then reduced. At the same time the chlorophyll a/b value became smaller. Under natural light, the plants tended to consume more water and the soil temperature at 15：00 p. m was higher. There was a smaller difference among various treatments. [ Conclusion]The suitable shading treatment to the growth of A. triloba seedlings was under the light transmittance rate of 50% and height and stem diameter of trees increased fast. Chlorophyll a （ Chl. a）, chlorophyll b （ Chl. b） content in leaves of A. triloba seedlings were highest comparing with those in other conditions.展开更多
The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and nume...The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope（OM） and scanning electron microscope（SEM）, which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element（FE） models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress-strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.展开更多
In order to extract froth morphological feature,a bubble image adaptive segmentation method was proposed.Considering the image's low contrast and weak froth edges,froth image was coarsely segmented by using fuzzy ...In order to extract froth morphological feature,a bubble image adaptive segmentation method was proposed.Considering the image's low contrast and weak froth edges,froth image was coarsely segmented by using fuzzy c means(FCM) algorithm. Through the attributes of size and shape pattern spectrum,the optimal morphological structuring element was determined.According to the optimal parameters,some image noises were removed with an improved area opening and closing by reconstruction operation,which consist of image regional markers,and the bubbles were finely separated from each other by watershed transform.The experimental results show that the structural element can be determined adaptively by shape and size pattern spectrum,and the froth image is segmented accurately.Compared with other froth image segmentation method,the proposed method achieves much high accuracy,based on which,the bubble size and shape features are extracted effectively.展开更多
基金Project(ID42787)supported by the Istanbul Technical University,BAP(Scientific Research Project)Department,Turkey。
文摘Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble size.For the same volume system,fewer bubbles result from a distribution of large-sized bubbles,and more bubbles result from a distribution of small-sized bubbles.In this research,fundamental two-phase frother characterization parameters were aimed to link with three-phase coal and talc flotation behavior.For this purpose,the effect of single and dual frother systems on inhibiting bubble coalescence was investigated with methyl isobutyl carbinol(MIBC),isooctanol(2 ethyl hexanol),pine oil,and Dowfroth 250.Based on the results of single frothers,isooctanol at the lowest critical coalescence concentration(CCC)value of 6×10^(−6) achieved the smallest bubbles with Sauter mean diameter of 0.80 mm.By blending Dowfroth 250 and pine oil,the bubbles size decreased significantly,reaching 0.45 mm.While the highest recoveries in coal flotation were obtained in single and frother blends where the bubbles size was measured as the smallest in two-phase system,and such a relationship was not found for talc flotation.
基金Project (2004AA33G060) supported by the National High-tech Research and Development Program of China
文摘Aluminum foams were fabricated by melt-based route using ZrH2 as a foaming agent. The factors which affected the foaming of aluminum foams during casting process were investigated. The powdered zirconium hydride with content of 0.6%-1.4% （mass fraction） was added to the molten pure aluminum and the foaming condition was controlled in a temperature range from 933 to 1 013 K, Ca amount of 1.5%-3.0% （mass fraction）, stirring time of 0.5-2.5 min and holding time of 1.5-4.0 min to obtain homogeneous aluminum foams. The fabricated aluminum foams were characterized by XRD, SEM and Image-pro plus. The mechanical properties of the aluminum foams with different relative density were tested. The result indicates that the foaming agent （ZrH2） is suitable for the preparation of small aperture aluminum foams with average pore diameter of 1 mm. Inter-metallic compounds and Al2O3 have effect on the melt viscosity. The aluminum foams experience linear elastic, platforms and densification process and had a higher efficiency of energy absorption.
基金Project(51174229)supported by the National Natural Science Foundation of China
文摘A new method of testing frother performance was proposed. Four parameters were tested： maximum foam volume, foam half-life, gas-liquid ratio and mean foam rise velocity. Among them the former two parameters indicate frother＇s foaming ability and foam stability respectively, and the latter two indicate water carrying ability and foam viscosity, respectively. The performance of four frothers in a two-phase （solution-air） system was tested and batch flotation tests on a copper ore were carried out. By analyzing frother performance in a two-phase system and comparing with the flotation results, correlation between them was found. Higher-copper concentrate grade was obtained by frothers with weak water carrying ability and low foam viscosity. And frothers with strong foaming ability and stable foam tend to obtain higher copper recovery.
基金Projects (50974035,51074047) supported by the National Natural Science Foundation of ChinaProject (20090407) supported by the Doctoral Fund of Ministry of Education,ChinaProject (200921007) supported by Liaoning Key Science and Technology,China
文摘In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.
基金Supported by the National"948"Import Program(2001-46)~~
文摘[Objective]The study was conducted to investigate the effects of shading treatments on growth of Asimina triloba （L） Dunal seedlings and provided the theoretical basis for seedling production. [Method]70 day-old A. triloba seedlings had similar stem diameter and plant height and good growth vigour were taken as tested materials in 2005. 4 light gradient treatments which were the natural light with 100% light intensity, one-layer, two-layer and three-layer black shading network with the light transmittance rate of 50%, 25% and 12.5% were set up to study the effects of different shading treatments on growth of A. triloba. [ Result] With the shading treatments of one-layer and two-layer net, the plants of A. triloba seedlings grew rapidly. As the intensity of illumination decreased, the cetents of chlorophyll a （ Chl. a）, chlorophyll b （ Chl. b） and total chlorophyll increased at first and then reduced. At the same time the chlorophyll a/b value became smaller. Under natural light, the plants tended to consume more water and the soil temperature at 15：00 p. m was higher. There was a smaller difference among various treatments. [ Conclusion]The suitable shading treatment to the growth of A. triloba seedlings was under the light transmittance rate of 50% and height and stem diameter of trees increased fast. Chlorophyll a （ Chl. a）, chlorophyll b （ Chl. b） content in leaves of A. triloba seedlings were highest comparing with those in other conditions.
基金Project(2013DFR50330)supported by the International Cooperation Project of Science and Technology Ministry of China
文摘The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope（OM） and scanning electron microscope（SEM）, which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element（FE） models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress-strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.
基金Projects(60634020,60874069) supported by the National Natural Science Foundation of ChinaProject(2009AA04Z137) supported by the National High-Tech Research and Development Program of China
文摘In order to extract froth morphological feature,a bubble image adaptive segmentation method was proposed.Considering the image's low contrast and weak froth edges,froth image was coarsely segmented by using fuzzy c means(FCM) algorithm. Through the attributes of size and shape pattern spectrum,the optimal morphological structuring element was determined.According to the optimal parameters,some image noises were removed with an improved area opening and closing by reconstruction operation,which consist of image regional markers,and the bubbles were finely separated from each other by watershed transform.The experimental results show that the structural element can be determined adaptively by shape and size pattern spectrum,and the froth image is segmented accurately.Compared with other froth image segmentation method,the proposed method achieves much high accuracy,based on which,the bubble size and shape features are extracted effectively.
