Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO_(3)and leaching with Na_(2)CO_(3)was investigated.The concentration of Cr residue in the so...Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO_(3)and leaching with Na_(2)CO_(3)was investigated.The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO_(3)into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5,adjusting the pH to 3.0 and stirring for 180 min at 30℃.Then,the precipitates were leached with hot Na_(2)CO_(3)solution to obtain leaching solution containing Na_(2)CrO_(4)and leaching residue containing PbCO_(3).The leaching efficiency of Cr reaches 96.43%by adding the precipitates into 0.5 mol/L Na_(2)CO_(3)solution with the mass ratio of liquid to solid(L/S)of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70℃.After filtration,leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na_(2)CrO_(4)approaches the saturation.Finally,the product of Na_(2)CrO_(4)·4H_(2)O is obtained by evaporation and crystallization of leaching solution.展开更多
The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadi...The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadium pentoxide.By adding Ca(OH)_(2) and ball milling,not only the V in the solution can be selectively precipitated,but also the leaching kinetics of the precipitate is significantly improved.The precipitation efficiency of V is 99.59%by adding Ca(OH)_(2) according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature,while the content of Cr in the precipitate is 0.04%.The leaching rate of V reaches 99.35%by adding NaHCO_(3) into water according to NaHCO_(3)/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature.The crystals of NH_(4)VO_(3) are obtained by adjusting the leaching solution pH to be 8.0 with CO2 and then adding NH_(4)HCO_(3) according to NH_(4)HCO_(3)/NaVO_(3) molar ratio of 1:1 and stirring for 8 h at room temperature.After filtration,the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates,and the leaching efficiency of V is>99%after stirring for 1 h at room temperature.Finally,the product of V_(2)O_(5) with purity of 99.6%is obtained by calcining the crystals at 560℃ for 2 h.展开更多
The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and ...The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and the mechanical properties in the axial direction of the tubes after the CRB process were studied with the OM,EBSD and conventional tensile test.To obtain the accumulated effective plastic strain of the tube during the CRB process,the FEM simulation was also executed.The results show that the average grain size decreases with the increase of rotation time at RT,and with the decrease of bending angle at 200℃.With the increase of accumulated effective plastic strain during the CRB process,the reduction rate of average grain size of the brass tube increases,the tensile strength of the brass tube increases in wave shape and the elongation increases first and then sharply decreases.展开更多
Al-Cu-Y alloys were prepared by molten salt electrolysis in fluoride-oxide system composed of electrolyte（Na3 AlF6-AlF3-LiF-MgF2） and oxide（Al2 O3-CuO-Y2 O3）. Cathodic reduction process of Al2 O3,CuO and Y2 O3 wer...Al-Cu-Y alloys were prepared by molten salt electrolysis in fluoride-oxide system composed of electrolyte（Na3 AlF6-AlF3-LiF-MgF2） and oxide（Al2 O3-CuO-Y2 O3）. Cathodic reduction process of Al2 O3,CuO and Y2 O3 were analyzed by cyclic voltammetry and chronoamperometry. Components and phase composition of alloy samples prepared by potentiostatic electrolysis were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results show that the Al-Cu-Y alloy can be prepared in the AIF3-NaF-5 wt%LiF-5 wt%MgF2（NaF/AlF3 = 2.2, molecular ratio） eutectic system with mixed oxide（Al2 O3-CuO-Y2 O3） through 2 h at the conditions of a temperature of 1208 K, cell voltage3.0 V, cathode current density 0.7 A/cm^2. Al（Ⅲ） and Cu（Ⅱ） ions can be reduced to zero valence Al（0） and Cu（0） directly on carbonaceous electrode surface by instantaneous nucleation, respectively, the reduction process is controlled by diffusion. The reduction potential of Y（Ⅲ） ions is close to the active ions of fluoride melts, but strengthened phase AI3 Y can be formed through electrochemical reduction and alloyed process with active Al（Ⅲ） and Cu（Ⅱ） ions, meanwhile, the Al2 Cu and Al3 Y phases are distributed at the grain boundary of Al matrix.展开更多
The mechanism of cathode process of B(Ⅲ) at molybdenum and platinum electrodes in LiF-NaF-KBF4melt was studied and the transferred electron number of the reaction was calculated by means of cyclic voltammetry.The eff...The mechanism of cathode process of B(Ⅲ) at molybdenum and platinum electrodes in LiF-NaF-KBF4melt was studied and the transferred electron number of the reaction was calculated by means of cyclic voltammetry.The effect of adsorption of electroactive component on the electrochemical response (e. g., the voltammetric i─Ecurves) was analyzed and discussed. The 'electrochemical spectra' for linear sweep voltammetry was used to elucidate the electrode reaction accompanied by a following transform process. The results show that the reduction ofB(Ⅲ) to B(0) proceeds in reversible one step three-electron reaction and the cathode process of B(Ⅲ) is affected byproduct adsorbed strongly at the electrode surface. It is assumed that the reduction and deposition of B(Ⅲ) at molybdenum and platinum electrodes proceed in two kinds of mechanism： (1) B(Ⅲ)＋ 3e = Bads→ B (surface diffusiondeposition mechanism) and (2) B(Ⅲ) ＋ 3e = B (direct deposition mechanism).展开更多
The reduction of yttrium ion on copper electrode in NaCl-KCl-YCl3 molten salts has been investigated.The results indicate that several humps for formation of intermetallic compounds occur before metallic yttrium is pr...The reduction of yttrium ion on copper electrode in NaCl-KCl-YCl3 molten salts has been investigated.The results indicate that several humps for formation of intermetallic compounds occur before metallic yttrium is produced. The formation of intermetallic compounds is controlled by diffusion of yttrium into copper electrode. The application of theoretical results to diffusion of yttrium atoms into copper substrate is discussed also.展开更多
In this study, the electrochemical reduction of Y(Ⅲ)on nickel electrode has been investigated. The resultsshow that there are several plateaus for formation of intermetallic compounds preceding reduction peak ofyttri...In this study, the electrochemical reduction of Y(Ⅲ)on nickel electrode has been investigated. The resultsshow that there are several plateaus for formation of intermetallic compounds preceding reduction peak ofyttrium. A linear relationship between the current and t￣(-1/2) has been obtained, showing that Cottrell's law isobeyed.展开更多
There are few biomechanical studies on Interspinous Process Implants (IPD);however none investigate the amount of wear on spinous processes. Therefore the objective of the present study was to investigate the effect o...There are few biomechanical studies on Interspinous Process Implants (IPD);however none investigate the amount of wear on spinous processes. Therefore the objective of the present study was to investigate the effect of repetitive loading of the IPD Aperius on the spinous processes in a biomechanical porcine model. For comparison, three patients treated surgically with the same device have been followed for one to two years clinically and with image analyses (X-rays, MRI, CT-scans). Four lumbar spines from 6 months old porcine were divided into seven segments, which received IPD. The segments were exposed to 20,000 cyclical loads. Afterwards the deformation (wear) of the segments was registered. The wear of the spinous processes was measured in mm on a following CT-scan. Additionally, the wear of the ex-vivo was compared to that of the spinous processes investigated by CT-scans or X-ray in three patients treated surgically with the same interspinous implant. The mean maximal deformation of porcine specimens was 1.79 mm (SD 0.25) with the largest deformation occurring in the first quarter of the loading (<5000 cycles). The mean wear of the spinous processes after loading was 6.57 mm. A similar level of wear (mean 12.7 mm) of the spinous processes was detected in the patients. The Aperius IPD creates significant wear on the spinous processes in an experimental biomechanical study. Similar wear of the spinous processes is also present in patients treated with the same device post-operatively. How these findings influence the short and long term result of this implant device remains to be investigated in further biomechanical as well as clinical studies. For future development of this type of devices a proper selection of materials and design is essential to minimize wear effects on the spinous processes and thereby increases the possibilities for the devices to function as suggested.展开更多
The comprehensive improvement strategy of intra-county environment pollution in the city and countryside was searched.By the research method which combined the microscopic view,the macroscopic view with the dynamic pe...The comprehensive improvement strategy of intra-county environment pollution in the city and countryside was searched.By the research method which combined the microscopic view,the macroscopic view with the dynamic perspective,the seriousness of rural water quality,soil and atmospheric pollution in Xiangxiang,Xiangtan and the surrounding areas in Shaoshan irrigated area was revealed.The control measure which was 'four-dimensional pollution in the city and countryside'—— low-carbon-high-value agriculture and the technology innovation was proposed.The low-carbon-high-value technology innovation industrialization demonstration in three parts which included the pre-production,mid-production and post-production deep-processing of cultivation and breeding industry in the ecological cyclic agricultural garden in Shaoshan irrigated area was the driving force.We tried to propel the low-carbon ecological cultivation and breeding industry which included the paddy rice,grass,tree,medicinal herbs and pig,cow,chick,duck,fish.We wanted to relieve the structural unbalance of previous cultivation and breeding industry,'cheap grain hurting the farmers' and the short-leg problem of social-economic-ecological benefit.The results showed that the low-carbon-high-value agricultural system was a poly-generation technology system which promoted the multi-level and grading utilization,saved the energy,reduced the consumption and cleaned the production based on the ecology.展开更多
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(No.51974369)NSFC-STINT(No.52111530192)+1 种基金Postgraduate Research Innovation Project of Central South University,China(No.2019zzts244)the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China(No.CSUZC202029).
文摘Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO_(3)and leaching with Na_(2)CO_(3)was investigated.The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO_(3)into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5,adjusting the pH to 3.0 and stirring for 180 min at 30℃.Then,the precipitates were leached with hot Na_(2)CO_(3)solution to obtain leaching solution containing Na_(2)CrO_(4)and leaching residue containing PbCO_(3).The leaching efficiency of Cr reaches 96.43%by adding the precipitates into 0.5 mol/L Na_(2)CO_(3)solution with the mass ratio of liquid to solid(L/S)of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70℃.After filtration,leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na_(2)CrO_(4)approaches the saturation.Finally,the product of Na_(2)CrO_(4)·4H_(2)O is obtained by evaporation and crystallization of leaching solution.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51974369)the Postgraduate Research Innovation Project of Central South University,China(2019zzts244).
文摘The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadium pentoxide.By adding Ca(OH)_(2) and ball milling,not only the V in the solution can be selectively precipitated,but also the leaching kinetics of the precipitate is significantly improved.The precipitation efficiency of V is 99.59%by adding Ca(OH)_(2) according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature,while the content of Cr in the precipitate is 0.04%.The leaching rate of V reaches 99.35%by adding NaHCO_(3) into water according to NaHCO_(3)/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature.The crystals of NH_(4)VO_(3) are obtained by adjusting the leaching solution pH to be 8.0 with CO2 and then adding NH_(4)HCO_(3) according to NH_(4)HCO_(3)/NaVO_(3) molar ratio of 1:1 and stirring for 8 h at room temperature.After filtration,the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates,and the leaching efficiency of V is>99%after stirring for 1 h at room temperature.Finally,the product of V_(2)O_(5) with purity of 99.6%is obtained by calcining the crystals at 560℃ for 2 h.
基金the National Natural Science Foundation of China(No.51304046)the Grant-in-Aid for Young Scientists(B)of Japan Society for the Promotion of Science of Japan(No.25870594)。
文摘The cyclic rotating−bending(CRB)processes under different deformation conditions were carried out to refine the microstructure and improve the mechanical properties of the 65Cu−35Zn brass tubes.The microstructure and the mechanical properties in the axial direction of the tubes after the CRB process were studied with the OM,EBSD and conventional tensile test.To obtain the accumulated effective plastic strain of the tube during the CRB process,the FEM simulation was also executed.The results show that the average grain size decreases with the increase of rotation time at RT,and with the decrease of bending angle at 200℃.With the increase of accumulated effective plastic strain during the CRB process,the reduction rate of average grain size of the brass tube increases,the tensile strength of the brass tube increases in wave shape and the elongation increases first and then sharply decreases.
基金Project supported by the National Natural Science Foundation of China(51564015)
文摘Al-Cu-Y alloys were prepared by molten salt electrolysis in fluoride-oxide system composed of electrolyte（Na3 AlF6-AlF3-LiF-MgF2） and oxide（Al2 O3-CuO-Y2 O3）. Cathodic reduction process of Al2 O3,CuO and Y2 O3 were analyzed by cyclic voltammetry and chronoamperometry. Components and phase composition of alloy samples prepared by potentiostatic electrolysis were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results show that the Al-Cu-Y alloy can be prepared in the AIF3-NaF-5 wt%LiF-5 wt%MgF2（NaF/AlF3 = 2.2, molecular ratio） eutectic system with mixed oxide（Al2 O3-CuO-Y2 O3） through 2 h at the conditions of a temperature of 1208 K, cell voltage3.0 V, cathode current density 0.7 A/cm^2. Al（Ⅲ） and Cu（Ⅱ） ions can be reduced to zero valence Al（0） and Cu（0） directly on carbonaceous electrode surface by instantaneous nucleation, respectively, the reduction process is controlled by diffusion. The reduction potential of Y（Ⅲ） ions is close to the active ions of fluoride melts, but strengthened phase AI3 Y can be formed through electrochemical reduction and alloyed process with active Al（Ⅲ） and Cu（Ⅱ） ions, meanwhile, the Al2 Cu and Al3 Y phases are distributed at the grain boundary of Al matrix.
文摘The mechanism of cathode process of B(Ⅲ) at molybdenum and platinum electrodes in LiF-NaF-KBF4melt was studied and the transferred electron number of the reaction was calculated by means of cyclic voltammetry.The effect of adsorption of electroactive component on the electrochemical response (e. g., the voltammetric i─Ecurves) was analyzed and discussed. The 'electrochemical spectra' for linear sweep voltammetry was used to elucidate the electrode reaction accompanied by a following transform process. The results show that the reduction ofB(Ⅲ) to B(0) proceeds in reversible one step three-electron reaction and the cathode process of B(Ⅲ) is affected byproduct adsorbed strongly at the electrode surface. It is assumed that the reduction and deposition of B(Ⅲ) at molybdenum and platinum electrodes proceed in two kinds of mechanism： (1) B(Ⅲ)＋ 3e = Bads→ B (surface diffusiondeposition mechanism) and (2) B(Ⅲ) ＋ 3e = B (direct deposition mechanism).
文摘The reduction of yttrium ion on copper electrode in NaCl-KCl-YCl3 molten salts has been investigated.The results indicate that several humps for formation of intermetallic compounds occur before metallic yttrium is produced. The formation of intermetallic compounds is controlled by diffusion of yttrium into copper electrode. The application of theoretical results to diffusion of yttrium atoms into copper substrate is discussed also.
文摘In this study, the electrochemical reduction of Y(Ⅲ)on nickel electrode has been investigated. The resultsshow that there are several plateaus for formation of intermetallic compounds preceding reduction peak ofyttrium. A linear relationship between the current and t￣(-1/2) has been obtained, showing that Cottrell's law isobeyed.
文摘There are few biomechanical studies on Interspinous Process Implants (IPD);however none investigate the amount of wear on spinous processes. Therefore the objective of the present study was to investigate the effect of repetitive loading of the IPD Aperius on the spinous processes in a biomechanical porcine model. For comparison, three patients treated surgically with the same device have been followed for one to two years clinically and with image analyses (X-rays, MRI, CT-scans). Four lumbar spines from 6 months old porcine were divided into seven segments, which received IPD. The segments were exposed to 20,000 cyclical loads. Afterwards the deformation (wear) of the segments was registered. The wear of the spinous processes was measured in mm on a following CT-scan. Additionally, the wear of the ex-vivo was compared to that of the spinous processes investigated by CT-scans or X-ray in three patients treated surgically with the same interspinous implant. The mean maximal deformation of porcine specimens was 1.79 mm (SD 0.25) with the largest deformation occurring in the first quarter of the loading (<5000 cycles). The mean wear of the spinous processes after loading was 6.57 mm. A similar level of wear (mean 12.7 mm) of the spinous processes was detected in the patients. The Aperius IPD creates significant wear on the spinous processes in an experimental biomechanical study. Similar wear of the spinous processes is also present in patients treated with the same device post-operatively. How these findings influence the short and long term result of this implant device remains to be investigated in further biomechanical as well as clinical studies. For future development of this type of devices a proper selection of materials and design is essential to minimize wear effects on the spinous processes and thereby increases the possibilities for the devices to function as suggested.
基金Supported by " Research on The Control Technology of Subtropical Agriculture Pollution System" Special Project of National Environment Protection Public Welfare Industry Science Research "Research on The Construction Strategy of Ecological Civilization" Development Plan Research Project of State Development and Reform Commission+1 种基金Xiangxiang " High-output and Efficient Cultivation of High Quality Rice and Processing Technology Industrialization Demonstration " in The Plan Test Site of National Science and Technology Enriching People and Developing County Special Project Action" Xiangxiang Middle and Long-term Development Plan of Modern Agriculture" of Subtropical Agriculture Ecology Institute in Chinese Academy of Science
文摘The comprehensive improvement strategy of intra-county environment pollution in the city and countryside was searched.By the research method which combined the microscopic view,the macroscopic view with the dynamic perspective,the seriousness of rural water quality,soil and atmospheric pollution in Xiangxiang,Xiangtan and the surrounding areas in Shaoshan irrigated area was revealed.The control measure which was 'four-dimensional pollution in the city and countryside'—— low-carbon-high-value agriculture and the technology innovation was proposed.The low-carbon-high-value technology innovation industrialization demonstration in three parts which included the pre-production,mid-production and post-production deep-processing of cultivation and breeding industry in the ecological cyclic agricultural garden in Shaoshan irrigated area was the driving force.We tried to propel the low-carbon ecological cultivation and breeding industry which included the paddy rice,grass,tree,medicinal herbs and pig,cow,chick,duck,fish.We wanted to relieve the structural unbalance of previous cultivation and breeding industry,'cheap grain hurting the farmers' and the short-leg problem of social-economic-ecological benefit.The results showed that the low-carbon-high-value agricultural system was a poly-generation technology system which promoted the multi-level and grading utilization,saved the energy,reduced the consumption and cleaned the production based on the ecology.
