Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepare...Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.展开更多
A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation： ① The low frequency resonance...A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation： ① The low frequency resonances introduced into the system; ② Conflict between lower isolation frequency and stiffness high enough to limit quasi-static stroke;③ Inconsistent isolation level with different force load. The design of two separate chambers is for the purpose of tuning support frequency and force independently and each chamber is controlled by a different valve. The inner one of double-loop structure is pressure control, and in order to obtain good performance, nonlinearities compensation and motion flow rate compensation （MFRC） are added besides the basic cascade compensation, and the influence of tube length is studied. The outer loop has two functions： one is to eliminate the resonance caused by isolation support and to broaden the isolation frequency band by payload velocity feedback and base velocity feed forward, and the other is to tune support force and support stiffness simultaneously and independently, which means the support force will have no effect on support stiffness. Theoretical analysis and experiment results show that the three drawbacks are overcome simultaneously.展开更多
This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impuri...This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impurities. The effects of pulp pH, solid content, reagents dosage(depressant, collector and co-collector) and conditioning time were investigated on the ratio of the modified rate constant of phosphate to the modified rate constant of iron(relative floatability). The results showed that a large dosage of depressant associated with a low value of collector resulted in a better relative floatability. Increasing the co-collector dosage, conditioning time and pH increased the relative floatability up to a certain value and thereafter resulted in diminishing the relative floatability. Meanwhile, the results indicated that increment of solid concentration increased the relative floatability in range investigated. It was also found that that maximum relative floatability(16.05) could be obtained in pulp pH, 9.32, solid percentage, 30,depressant dosage, 440 g/t, collector dosage, 560 g/t, co-collector dosage, 84.63 g/t and conditioning time,9.43 min.展开更多
Coal is primarily beneficiated by wet gravity methods. The wet processing of coal is an efficient practice. However, it introduces the moisture in the range of 6%-15%, depending upon the size of coal which is as detri...Coal is primarily beneficiated by wet gravity methods. The wet processing of coal is an efficient practice. However, it introduces the moisture in the range of 6%-15%, depending upon the size of coal which is as detrimental as ash content to the heating value of coal. Dry beneficiation of coal fines was carried out using an air fluidized vibrating table in which the coal particles get separated from the heavier mineral particles as a result of horizontal and vertical stratification. Two level factorial design matrix was used to optimize and assess the interactive effects of the operational parameters of a pneumatic table viz. deck eccentric, side tilt and air flow rate on the clean coal yield and its ash content. Double stage processing was found to be more effective for reducing the ash content of the clean coal. Initial stage of processing at a higher ash level generates a reject of high ash with low combustibles. Cleaning of the rougher concentrate at 34%-35% ash level shows significant improvement in the organic efficiency （88.6%） and useful heat value of clean coal （15690 kJ/kg）. The performance of air fluidized vibrating deck was measured by Ep value which is 0.18.展开更多
The pre-reduced Bayan Obo ferroniobium（FeNb）ore concentrate block was taken as raw materials for studying the physical properties of niobium-enriched slag and changes in niobium recovery rate.In addition,the dephosp...The pre-reduced Bayan Obo ferroniobium（FeNb）ore concentrate block was taken as raw materials for studying the physical properties of niobium-enriched slag and changes in niobium recovery rate.In addition,the dephosphorization rate of the slag under different melting-separation conditions was investigated using the melting-separation test.The research results demonstrate that（i）the niobium recovery rate and dephosphorization rate of the slag decrease with the increase in melting-separation temperature;（ii）the niobium recovery rate of the slag initially increases and then decreases with increase in basicity and time;and（iii）the dephosphorization rate of the slag increases with the increase in basicity and time.When the test was performed under the conditions of basicity of 0.6-0.7,time of 7-10min,and temperature of 1400-1450°C,the niobium recovery rate and dephosphorization rate are over 96%and 95%,respectively.By scanning electron microscopy,it is observed that niobium mainly exists in the form of calcium and titanium silicate within the slag phase,with uneven distribution.展开更多
The Eu（III） separation in supported dispersion liquid membrane （SDLM）, with polyvinylidene fluoride membrane （PVDF） as the support and dispersion solution containing HNO3 solution as the stripping solution and D...The Eu（III） separation in supported dispersion liquid membrane （SDLM）, with polyvinylidene fluoride membrane （PVDF） as the support and dispersion solution containing HNO3 solution as the stripping solution and Di（2-ethylhexyl） phosphoric acid （D2EHPA） dis- solved in kerosene as the membrane solution, was studied. The effects ofpH value, initial concentration of Eu（III） and different ionic strengths in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HNO3 solution, concentration of carrier, different stripping agents in the dispersion phase on the separation of Eu（III） were also investigated, respectively. As a result, the optimum separation conditions of Eu（III） were obtained as the concentration of HNO3 solution was 4.00 mol/L, concentration of D2EHPA was 0.160 mol/L, and volume ratio of membrane solution to stripping solution was 30：30 in the dispersion phase, and pH value was 5.00 in the feed phase. Ionic strength had no obvious effect on the separation of Eu（III）. Under the optimum conditions studied, when initial concentration of Eu（III） was 1.00× 10^-4 mol/L, the separation rate of Eu（III） was up to 94.2% during the separation period of 35 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.展开更多
In this article,we review the advancement in nanoseparation and concomitant purification of nanoparticles(NPs) by using density gradient ultracentrifugation technique(DGUC) and demonstrated by taking several typical e...In this article,we review the advancement in nanoseparation and concomitant purification of nanoparticles(NPs) by using density gradient ultracentrifugation technique(DGUC) and demonstrated by taking several typical examples.Study emphasizes the conceptual advances in classification,mechanism of DGUC and synthesis-structure-property relationships of NPs to provide the significant clue for the further synthesis optimization.Separation,concentration,and purification of NPs by DGUC can be achieved at the same time by introducing the water/oil interfaces into the separation chamber.We can develop an efficient method ‘‘lab in a tube" by introducing a reaction zone or an assembly zone in the gradient to find the surface reaction and assembly mechanism of NPs since the reaction time can be precisely controlled and the chemical environment change can be extremely fast.Finally,to achieve the best separation parameters for the colloidal systems,we gave the mathematical descriptions and computational optimized models as a new direction for making practicable and predictable DGUC separation method.Thus,it can be helpful for an efficient separation as well as for the synthesis optimization,assembly and surface reactions as a potential cornerstone for the future development in the nanotechnology and this review can be served as a plethora of advanced notes on the DGUC separation method.展开更多
基金supported by Wuxi HIT New Material Research Institute and China Academy of Engineering Physics。
文摘Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.
基金This project is supported by Commission of Science Technology and Industry for National Defense, China.
文摘A newly designed pneumatic spring with two separate chambers is promoted and double-loop active control is introduced to overcome the following drawbacks of passive pneumatic isolation： ① The low frequency resonances introduced into the system; ② Conflict between lower isolation frequency and stiffness high enough to limit quasi-static stroke;③ Inconsistent isolation level with different force load. The design of two separate chambers is for the purpose of tuning support frequency and force independently and each chamber is controlled by a different valve. The inner one of double-loop structure is pressure control, and in order to obtain good performance, nonlinearities compensation and motion flow rate compensation （MFRC） are added besides the basic cascade compensation, and the influence of tube length is studied. The outer loop has two functions： one is to eliminate the resonance caused by isolation support and to broaden the isolation frequency band by payload velocity feedback and base velocity feed forward, and the other is to tune support force and support stiffness simultaneously and independently, which means the support force will have no effect on support stiffness. Theoretical analysis and experiment results show that the three drawbacks are overcome simultaneously.
基金the phosphate Esfordi MineShahrood University of Technology for their support during this research
文摘This work was aimed to study the relative floatability of phosphate flotation by means of kinetic analysis.The relative floatability is important to determine how selectively the phosphate is separated from its impurities. The effects of pulp pH, solid content, reagents dosage(depressant, collector and co-collector) and conditioning time were investigated on the ratio of the modified rate constant of phosphate to the modified rate constant of iron(relative floatability). The results showed that a large dosage of depressant associated with a low value of collector resulted in a better relative floatability. Increasing the co-collector dosage, conditioning time and pH increased the relative floatability up to a certain value and thereafter resulted in diminishing the relative floatability. Meanwhile, the results indicated that increment of solid concentration increased the relative floatability in range investigated. It was also found that that maximum relative floatability(16.05) could be obtained in pulp pH, 9.32, solid percentage, 30,depressant dosage, 440 g/t, collector dosage, 560 g/t, co-collector dosage, 84.63 g/t and conditioning time,9.43 min.
文摘Coal is primarily beneficiated by wet gravity methods. The wet processing of coal is an efficient practice. However, it introduces the moisture in the range of 6%-15%, depending upon the size of coal which is as detrimental as ash content to the heating value of coal. Dry beneficiation of coal fines was carried out using an air fluidized vibrating table in which the coal particles get separated from the heavier mineral particles as a result of horizontal and vertical stratification. Two level factorial design matrix was used to optimize and assess the interactive effects of the operational parameters of a pneumatic table viz. deck eccentric, side tilt and air flow rate on the clean coal yield and its ash content. Double stage processing was found to be more effective for reducing the ash content of the clean coal. Initial stage of processing at a higher ash level generates a reject of high ash with low combustibles. Cleaning of the rougher concentrate at 34%-35% ash level shows significant improvement in the organic efficiency （88.6%） and useful heat value of clean coal （15690 kJ/kg）. The performance of air fluidized vibrating deck was measured by Ep value which is 0.18.
基金financially supported by the National Science and Technology Support Program (2008BAB32087)
文摘The pre-reduced Bayan Obo ferroniobium（FeNb）ore concentrate block was taken as raw materials for studying the physical properties of niobium-enriched slag and changes in niobium recovery rate.In addition,the dephosphorization rate of the slag under different melting-separation conditions was investigated using the melting-separation test.The research results demonstrate that（i）the niobium recovery rate and dephosphorization rate of the slag decrease with the increase in melting-separation temperature;（ii）the niobium recovery rate of the slag initially increases and then decreases with increase in basicity and time;and（iii）the dephosphorization rate of the slag increases with the increase in basicity and time.When the test was performed under the conditions of basicity of 0.6-0.7,time of 7-10min,and temperature of 1400-1450°C,the niobium recovery rate and dephosphorization rate are over 96%and 95%,respectively.By scanning electron microscopy,it is observed that niobium mainly exists in the form of calcium and titanium silicate within the slag phase,with uneven distribution.
基金Project supported by the National Natural Science Foundation of China (90401009)the Action Plan for the Development of Western China of the Chinese Academy of Sciences (KZCX2-XB2-13)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (602-210805)
文摘The Eu（III） separation in supported dispersion liquid membrane （SDLM）, with polyvinylidene fluoride membrane （PVDF） as the support and dispersion solution containing HNO3 solution as the stripping solution and Di（2-ethylhexyl） phosphoric acid （D2EHPA） dis- solved in kerosene as the membrane solution, was studied. The effects ofpH value, initial concentration of Eu（III） and different ionic strengths in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HNO3 solution, concentration of carrier, different stripping agents in the dispersion phase on the separation of Eu（III） were also investigated, respectively. As a result, the optimum separation conditions of Eu（III） were obtained as the concentration of HNO3 solution was 4.00 mol/L, concentration of D2EHPA was 0.160 mol/L, and volume ratio of membrane solution to stripping solution was 30：30 in the dispersion phase, and pH value was 5.00 in the feed phase. Ionic strength had no obvious effect on the separation of Eu（III）. Under the optimum conditions studied, when initial concentration of Eu（III） was 1.00× 10^-4 mol/L, the separation rate of Eu（III） was up to 94.2% during the separation period of 35 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.
基金supported by the National Natural Science Foundation of China(NSFC)the National Key Research and Development Project of China(2016YFF0204402)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in the University(IRT1205)the Fundamental Research Funds for the Central Universities,the Long-Term Subsidy Mechanism from the Ministry of Finance and the Ministry of Education of PRC
文摘In this article,we review the advancement in nanoseparation and concomitant purification of nanoparticles(NPs) by using density gradient ultracentrifugation technique(DGUC) and demonstrated by taking several typical examples.Study emphasizes the conceptual advances in classification,mechanism of DGUC and synthesis-structure-property relationships of NPs to provide the significant clue for the further synthesis optimization.Separation,concentration,and purification of NPs by DGUC can be achieved at the same time by introducing the water/oil interfaces into the separation chamber.We can develop an efficient method ‘‘lab in a tube" by introducing a reaction zone or an assembly zone in the gradient to find the surface reaction and assembly mechanism of NPs since the reaction time can be precisely controlled and the chemical environment change can be extremely fast.Finally,to achieve the best separation parameters for the colloidal systems,we gave the mathematical descriptions and computational optimized models as a new direction for making practicable and predictable DGUC separation method.Thus,it can be helpful for an efficient separation as well as for the synthesis optimization,assembly and surface reactions as a potential cornerstone for the future development in the nanotechnology and this review can be served as a plethora of advanced notes on the DGUC separation method.
