A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and co...A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.展开更多
A packing-flotation column was proposed to optimize the flotation environment A research system was es- tablished using a 100 mm diameter cyclonic micro-bubble flotation column to study fluid properties. Dry-plate and...A packing-flotation column was proposed to optimize the flotation environment A research system was es- tablished using a 100 mm diameter cyclonic micro-bubble flotation column to study fluid properties. Dry-plate and wet- plate pressure drops were studied and the corresponding pressure drop equations developed. The results show that the dry-plate pressure drop of the packing cyclonic micro-bubble flotation column is 10–15 times less than that of the chemical tower, which is principally shown in its relatively small resistance coefficient, ξ ≈0.0207. The wet-plate pressure drop is 2–3 times higher than that of the chemical tower, which is largely caused by the separation materials and characteristics of the equipment. With flotation, the greater the pressure drop, the better the flotation environment.展开更多
The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its...The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its unique cyclonic force field. It also has been observed that the presence of a cyclonic force field leads to a lower bottom separation size limit and a reduction of unselective entrainment. The collection zone of the column is considered to consist of two parts,a column separation zone and a cyclonic zone. Total recovery of the collection zone was developed. For our study,we analyzed the particle movement in the cyclonic zone. Particle residence time equations for the cyclonic zone were de-rived by force analysis. Results obtained in this study provide a theoretical foundation for the design and scale-up of the FCSMC.展开更多
Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in bo...Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in both cross section and longitudinal section within cyclonic zone was studied for different circulating volumes. The cross sectional vortex was also analyzed. The results show that in cross section as the circulating volume increases from 0.187 to 0.350 m 3 /h, the flow velocity ranges from 0 to 0.68 m/s. The flow field is mainly a non-vortex potential flow that forms a free vortex without outside energy input. In the cyclonic region the vortex deviates from the center of the flotation column because a single tangential opening introduces circulating fluid into the column. The tangential component of the velocity plays a defining role in the cross section. In the longitudinal section the velocity ranges from 0 to 0.08 m/s. The flow velocity increases as does the circulating volume. Advantageous mineral separation conditions arise from the combined effects of cyclonic flow in cross and longitudinal section.展开更多
Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the f...Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the films before and after annealing are studied.It is found that the existence of an oxygen vacancy results in the decrease of the transmittance,refractive index,both macroscopic band gap and microscopic band gap,and the LIDT of Ta_(2)O_(5) films.If the oxygen vacancy forms,the macroscopic band gap decreases 2%.However,when the oxygen vacancy forms the microscopic band gap decreases 73%for crystalline Ta_(2)O_(5) and 77%for amorphous Ta_(2)O_(5).The serious decrease of microscopic band gap may significantly increase the absorbance of the micro-area in Ta_(2)O_(5) films when irradiated by laser,thus the damage probability increases.It is consistent with our experimental results that the LIDT of the as-deposited Ta_(2)O_(5) films is 7.3 J/cm^(2),which increases 26%to 9.2 J/cm^(2) when the oxygen vacancy is eliminated after annealing.展开更多
Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-in...Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-induced damage threshold(LIDT)of the films are comparatively studied.It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry,whereas it increases the absorption,scattering and rms roughness for both Ta_(2)O_(5) and Nb_(2)O_(5) films.However,the LIDT increases first and then decreases with the increase of electron beam current.In addition,the annealing improves the optical transmittance,stoichiometry and LIDT for the two kinds of films.Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors:substoichiometric defects,structural defects and adhesive force.Furthermore,the comparative results indicate that the laser damage resistance of Ta_(2)O_(5) is lower than that of Nb_(2)O_(5).展开更多
We address problems in the development of large-scale flotation columns that use short cylinders. As a starting point, we investigated the packing medium to identify a highly efficient internal packing for the flotati...We address problems in the development of large-scale flotation columns that use short cylinders. As a starting point, we investigated the packing medium to identify a highly efficient internal packing for the flotation column. The chosen packing was a honeycomb structure with an aperture diameter of 80 mm, a web thickness of 0.80 mm, a film height of 1000 mm, packed into a 400 mm diameter space, which completely filled the vessel at optimal cost. The column consisted of a modular ring of single-hole hexagonal honeycomb tube packing made from atactic polyproplene (PP-R). The packing was tested in a cyclonic, static micro-bubble flotation column. Computational fluid dynamic modeling was used to analyze the flotation fluid in a honeycomb tube packed flotation column. Our results show that the fluid axial movement was maximized and that the transverse fluid velocities were zero in the vicinity of axial flow. Using the honeycomb tube packing for copper sulfide flotation we observed that the average concentration in the product was increased to 25.41%, from an average feed concentration of 0.729%, with an average recovery of 92.92%. The demands of on-site industrial production were met.展开更多
基金Projects 50425414 supported by thte National Fund for Distinguished Young Scholars2006A019 by the Science and Technology Fund of China University of Mining &Technology
文摘A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.
基金Project 50425414 supported by the National Outstanding Youth Science Foundation of China
文摘A packing-flotation column was proposed to optimize the flotation environment A research system was es- tablished using a 100 mm diameter cyclonic micro-bubble flotation column to study fluid properties. Dry-plate and wet- plate pressure drops were studied and the corresponding pressure drop equations developed. The results show that the dry-plate pressure drop of the packing cyclonic micro-bubble flotation column is 10–15 times less than that of the chemical tower, which is principally shown in its relatively small resistance coefficient, ξ ≈0.0207. The wet-plate pressure drop is 2–3 times higher than that of the chemical tower, which is largely caused by the separation materials and characteristics of the equipment. With flotation, the greater the pressure drop, the better the flotation environment.
基金Project 50425414 supported by the National Outstanding Youth Science Foundation of China
文摘The cyclonic static micro-bubble column flotation (FCSMC) is an effective separation device for fine particle treatment. The high mineralization rate and short flotation time of this equipment can be attributed to its unique cyclonic force field. It also has been observed that the presence of a cyclonic force field leads to a lower bottom separation size limit and a reduction of unselective entrainment. The collection zone of the column is considered to consist of two parts,a column separation zone and a cyclonic zone. Total recovery of the collection zone was developed. For our study,we analyzed the particle movement in the cyclonic zone. Particle residence time equations for the cyclonic zone were de-rived by force analysis. Results obtained in this study provide a theoretical foundation for the design and scale-up of the FCSMC.
基金the State Key Basic Research Program of China (No. 2012CB214905)Key Program of National Natural Science Foundation of China (No. 500834006)the National Natural Science Foundation of China (No. 50974119) for financial support
文摘Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in both cross section and longitudinal section within cyclonic zone was studied for different circulating volumes. The cross sectional vortex was also analyzed. The results show that in cross section as the circulating volume increases from 0.187 to 0.350 m 3 /h, the flow velocity ranges from 0 to 0.68 m/s. The flow field is mainly a non-vortex potential flow that forms a free vortex without outside energy input. In the cyclonic region the vortex deviates from the center of the flotation column because a single tangential opening introduces circulating fluid into the column. The tangential component of the velocity plays a defining role in the cross section. In the longitudinal section the velocity ranges from 0 to 0.08 m/s. The flow velocity increases as does the circulating volume. Advantageous mineral separation conditions arise from the combined effects of cyclonic flow in cross and longitudinal section.
基金Supported by the National Natural Science Foundation of China(Nos 61107080,50921002)the Natural Science Foundation of Jiangsu Province of China(No BK2011223)+3 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(New Teachers)(No 20110095120018)the China Postdoctoral Science Foundation(No 20110491472)the National Undergraduate Innovation Experiment Programs(No 2012106)the Fundamental Research Funds for the Central Universities(No 2012QNA03).
文摘Ta_(2)O_(5) films are deposited on fused silica substrates by electron beam evaporation method.The optical property,x-ray photoelectron spectroscopy,band gap and nanosecond laser-induced damage threshold(LIDT)of the films before and after annealing are studied.It is found that the existence of an oxygen vacancy results in the decrease of the transmittance,refractive index,both macroscopic band gap and microscopic band gap,and the LIDT of Ta_(2)O_(5) films.If the oxygen vacancy forms,the macroscopic band gap decreases 2%.However,when the oxygen vacancy forms the microscopic band gap decreases 73%for crystalline Ta_(2)O_(5) and 77%for amorphous Ta_(2)O_(5).The serious decrease of microscopic band gap may significantly increase the absorbance of the micro-area in Ta_(2)O_(5) films when irradiated by laser,thus the damage probability increases.It is consistent with our experimental results that the LIDT of the as-deposited Ta_(2)O_(5) films is 7.3 J/cm^(2),which increases 26%to 9.2 J/cm^(2) when the oxygen vacancy is eliminated after annealing.
基金by the Youth Science Research Foundation of China University of Mining and Technology(No 2009A058)the Fundamental Research Funds for the Central Universities(No 2010Qnb06).
文摘Ta_(2)O_(5) and Nb_(2)O_(5) films are deposited by conventional e−beam method under different electron beam currents.The optical transmittance,chemical composition,absorption,scattering,surface topography and laser-induced damage threshold(LIDT)of the films are comparatively studied.It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry,whereas it increases the absorption,scattering and rms roughness for both Ta_(2)O_(5) and Nb_(2)O_(5) films.However,the LIDT increases first and then decreases with the increase of electron beam current.In addition,the annealing improves the optical transmittance,stoichiometry and LIDT for the two kinds of films.Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors:substoichiometric defects,structural defects and adhesive force.Furthermore,the comparative results indicate that the laser damage resistance of Ta_(2)O_(5) is lower than that of Nb_(2)O_(5).
基金Project 2007AA05Z339 supported by the National High-Tech Research and Development Program of China
文摘We address problems in the development of large-scale flotation columns that use short cylinders. As a starting point, we investigated the packing medium to identify a highly efficient internal packing for the flotation column. The chosen packing was a honeycomb structure with an aperture diameter of 80 mm, a web thickness of 0.80 mm, a film height of 1000 mm, packed into a 400 mm diameter space, which completely filled the vessel at optimal cost. The column consisted of a modular ring of single-hole hexagonal honeycomb tube packing made from atactic polyproplene (PP-R). The packing was tested in a cyclonic, static micro-bubble flotation column. Computational fluid dynamic modeling was used to analyze the flotation fluid in a honeycomb tube packed flotation column. Our results show that the fluid axial movement was maximized and that the transverse fluid velocities were zero in the vicinity of axial flow. Using the honeycomb tube packing for copper sulfide flotation we observed that the average concentration in the product was increased to 25.41%, from an average feed concentration of 0.729%, with an average recovery of 92.92%. The demands of on-site industrial production were met.