The feasibility of leaching and recovery of zinc from zinc leaching residue （ZLR） based on a membrane filter press （MFP） was investigated. Experimental results show that zinc calcines with particle sizes of less t...The feasibility of leaching and recovery of zinc from zinc leaching residue （ZLR） based on a membrane filter press （MFP） was investigated. Experimental results show that zinc calcines with particle sizes of less than 106 μm and chambers of widths of 30 mm are appropriate for establishing uniform filter cakes to obtain acceptable leaching and recovery results. The leaching of zinc from ZLR performed via washing at 90 to 96 ℃ for 90 min with spent electrolyte using a MFP results in a zinc extraction rate of 97%, and almost all of the zinc leached are recovered after water washing with MFP, thereby avoiding any loss in the ZLR. Compared with the traditional hot concentrated acid leaching process, the process based on MFP as a leaching reactor is able not only to ensure a high extraction rate but also to reduce the leaching time. Moreover, the thickening, pulping, second leaching, washing, filtering and pressing could be integrated and realized using a single MFP.展开更多
Imidacloprid is a newly introduced broad-spectrum chloronicotinyl insecticide and will find its way in agricultural production, particularly in Asia. However, information on the fate of imidacloprid in crop plants is ...Imidacloprid is a newly introduced broad-spectrum chloronicotinyl insecticide and will find its way in agricultural production, particularly in Asia. However, information on the fate of imidacloprid in crop plants is lacking. The degradation of imidaclopnd in processed CTC tea and tea liquor was investigated in the present study in which imidacloprid was applied at recommended application rate （30.0 g a.i./ha） and twice the recommended application rate （60.0 g a.i./ha） for three consecutive seasons. Imidacloprid was rapidly dissipated in processed tea following first order reaction kinetics at all application rates and had half-lives of 0.9 1-1.16 d with the residue in tea liquor found to be below detectable limit on 3rd day samples. The study revealed that imidacloprid is safe for human consumption and will not pose any residual toxicity problem.展开更多
Technology intensified with surface wettability was introduced to leach vanadium and chromium from converter vanadium slag without roasting. Parameters affecting the leaching efficiency of vanadium and chromium were i...Technology intensified with surface wettability was introduced to leach vanadium and chromium from converter vanadium slag without roasting. Parameters affecting the leaching efficiency of vanadium and chromium were investigated： sulfuric acid concentration, MnOz-to-slag mass ratio, liquid-to-solid ratio, leaching time, leaching temperature, and sodium dodecyl sulfate （SDS）-to-slag mass ratio. The leaching efficiencies of vanadium and chromium were 33.46 % and 20.02 % higher in the presence of MnO2 and SDS, respectively, compared to the control. The leaching efficiencies of vanadium and chromium were 68.93 % and 30.74 %, respectively, under the optimum conditions： sulfuric acid concentration 40 wt%, MnOz-to-slag mass ratio 10.0 wt%, liquid-to-solid ratio 5：1 mL/g; 12 h; 90 ~C; and SDS-to-slag mass ratio 0.25 wt%. The analysis of the reaction mechanism in the leaching process indicates that MnO2 combined with protons （H＋） could oxidize low-valent vanadium and chromium; SDS could change the chemical behavior and decrease the surface tension of the aqueous solution to favor MnO2 oxidization.展开更多
Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge c...Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge could seriously damage the ecological environment.In this study,an innovative method for cooperative removal Mn^(2+),NH_(4)^(+)-N,PO_(4)^(3-)-P,F^(-)from PG and POFT was studied.The result showed that Mn^(2+),PO_(4)^(3-)-P and F^(-)were mainly removed in forms of Mg_(3)Si_(4)O_(10)(OH)_(2),Mn_(3)O_(4),Mn_(3)(PO_(4))_(2),Mg_(3)(PO_(4))_(2),CaSO_(4)·2H_(2)O,MnF_(2),MnOOH and Ca_(2)P_(2)O_(7)·2H_(2)O,when LG-MgO was used to adjust the pH value of the system to 9.5,and the volume ratio of EMRL and PGL was 1:4,as well as reaction for 1 h at 25℃.NH_(4)^(+)-N was mainly removed by struvite precipitate,when the molar ratio of N:Mg:P was 1:3:2.4.The concentrations of Mn^(2+),NH_(4)^(+)-N and F^(-)were lower than the integrated wastewater discharge standard.The concentration of PO_(4)^(3-)-P decreased from 254.20 mg/L to 3.21 mg/L.This study provided a new method for EMRL and PGL cooperative harmless treatment.展开更多
文摘The feasibility of leaching and recovery of zinc from zinc leaching residue （ZLR） based on a membrane filter press （MFP） was investigated. Experimental results show that zinc calcines with particle sizes of less than 106 μm and chambers of widths of 30 mm are appropriate for establishing uniform filter cakes to obtain acceptable leaching and recovery results. The leaching of zinc from ZLR performed via washing at 90 to 96 ℃ for 90 min with spent electrolyte using a MFP results in a zinc extraction rate of 97%, and almost all of the zinc leached are recovered after water washing with MFP, thereby avoiding any loss in the ZLR. Compared with the traditional hot concentrated acid leaching process, the process based on MFP as a leaching reactor is able not only to ensure a high extraction rate but also to reduce the leaching time. Moreover, the thickening, pulping, second leaching, washing, filtering and pressing could be integrated and realized using a single MFP.
基金Project supported by Bayer Crop. Science India Ltd
文摘Imidacloprid is a newly introduced broad-spectrum chloronicotinyl insecticide and will find its way in agricultural production, particularly in Asia. However, information on the fate of imidacloprid in crop plants is lacking. The degradation of imidaclopnd in processed CTC tea and tea liquor was investigated in the present study in which imidacloprid was applied at recommended application rate （30.0 g a.i./ha） and twice the recommended application rate （60.0 g a.i./ha） for three consecutive seasons. Imidacloprid was rapidly dissipated in processed tea following first order reaction kinetics at all application rates and had half-lives of 0.9 1-1.16 d with the residue in tea liquor found to be below detectable limit on 3rd day samples. The study revealed that imidacloprid is safe for human consumption and will not pose any residual toxicity problem.
基金Project(2015BAB17B00)supported by the National Key Technology R&D Program of ChinaProject(CYB15045)supported by the Program for Chongqing University Postgraduates’ Innovation Project,China
文摘Technology intensified with surface wettability was introduced to leach vanadium and chromium from converter vanadium slag without roasting. Parameters affecting the leaching efficiency of vanadium and chromium were investigated： sulfuric acid concentration, MnOz-to-slag mass ratio, liquid-to-solid ratio, leaching time, leaching temperature, and sodium dodecyl sulfate （SDS）-to-slag mass ratio. The leaching efficiencies of vanadium and chromium were 33.46 % and 20.02 % higher in the presence of MnO2 and SDS, respectively, compared to the control. The leaching efficiencies of vanadium and chromium were 68.93 % and 30.74 %, respectively, under the optimum conditions： sulfuric acid concentration 40 wt%, MnOz-to-slag mass ratio 10.0 wt%, liquid-to-solid ratio 5：1 mL/g; 12 h; 90 ~C; and SDS-to-slag mass ratio 0.25 wt%. The analysis of the reaction mechanism in the leaching process indicates that MnO2 combined with protons （H＋） could oxidize low-valent vanadium and chromium; SDS could change the chemical behavior and decrease the surface tension of the aqueous solution to favor MnO2 oxidization.
基金Project(2018YFC1903500)supported by the National Key Research and Development Program of ChinaProject(52174386)supported by the National Natural Science Foundation of ChinaProject(2021YFH0058)supported by the Science and Technology Plan Project of Sichuan Province,China。
文摘Electrolytic manganese residue leachate(EMRL)contains plenty of Mn^(2+) and NH_(4)^(+)-N,and phosphogypsum leachate(PGL)contains large amounts of PO_(4)^(3-)-P and F^(-).Traditional methods of EMRL and PGL discharge could seriously damage the ecological environment.In this study,an innovative method for cooperative removal Mn^(2+),NH_(4)^(+)-N,PO_(4)^(3-)-P,F^(-)from PG and POFT was studied.The result showed that Mn^(2+),PO_(4)^(3-)-P and F^(-)were mainly removed in forms of Mg_(3)Si_(4)O_(10)(OH)_(2),Mn_(3)O_(4),Mn_(3)(PO_(4))_(2),Mg_(3)(PO_(4))_(2),CaSO_(4)·2H_(2)O,MnF_(2),MnOOH and Ca_(2)P_(2)O_(7)·2H_(2)O,when LG-MgO was used to adjust the pH value of the system to 9.5,and the volume ratio of EMRL and PGL was 1:4,as well as reaction for 1 h at 25℃.NH_(4)^(+)-N was mainly removed by struvite precipitate,when the molar ratio of N:Mg:P was 1:3:2.4.The concentrations of Mn^(2+),NH_(4)^(+)-N and F^(-)were lower than the integrated wastewater discharge standard.The concentration of PO_(4)^(3-)-P decreased from 254.20 mg/L to 3.21 mg/L.This study provided a new method for EMRL and PGL cooperative harmless treatment.
