The leaching behavior of main metallic sulphides in zinc concentrate under atmospheric oxygen-rich direct leaching conditions was studied through mineralogical analysis. The results show that the sulphides dissolve ob...The leaching behavior of main metallic sulphides in zinc concentrate under atmospheric oxygen-rich direct leaching conditions was studied through mineralogical analysis. The results show that the sulphides dissolve obviously except pyrite. Based on the relationship between elemental sulfur and the residual sulphides in the leaching residue, the dissolution of sphalerite, chalcopyrite, covellite and galena is assumed to follow the indirect oxidation reactions, where the acidic dissolution takes place firstly and then the released H2S transfers from the mineral surface into bulk solution and is further oxidized into elemental sulfur. The interface chemical reaction is further supposed as the controlling step in the leaching of these sulphides. The direct electrochemical oxidation reactions are assumed to contribute to the dissolution of pyrrhotite, which is controlled by the diffusion through elemental sulfur layer.展开更多
Effects of particle size of the zinc sulfide concentrate,leaching temperature,solid-to-liquid ratio and additive amount on pressure acid leaching process of the zinc sulfide concentrate were studied.The results indica...Effects of particle size of the zinc sulfide concentrate,leaching temperature,solid-to-liquid ratio and additive amount on pressure acid leaching process of the zinc sulfide concentrate were studied.The results indicate that the additive can improve the reaction kinetics and the conversion rate.And sulfur can be successfully separated from the zinc sulfide concentrate as elemental sulfur.The reasonable experiment parameters are obtained as follows:the leaching temperature 150℃,oxygen partial pressure 1 MPa,additive amount 1%,solid-to-liquid ratio 1:4,leaching time 2 h,initial sulfuric acid concentration 15%,and particle size less than 44μm.Under the optimum conditions,the leaching rate of the zinc can reach 95%and the reduction rate of the sulfur can reach 90%.展开更多
Zinc concentrate with high gallium content is one of the main resources of gallium.The gallium presents in the form of isomorphism in tetrahedron coordination with sulfur in sphalerite.The research was to investigate ...Zinc concentrate with high gallium content is one of the main resources of gallium.The gallium presents in the form of isomorphism in tetrahedron coordination with sulfur in sphalerite.The research was to investigate the amenability of zinc concentrate with high gallium to pressure oxygen leaching.The particle size,sulfuric acid concentration,oxygen partial pressure,additive amount,and time of reaction were studied.The extraction yields of gallium and zinc are 86%and 98%,respectively.The optimal condition is 100 g of zinc concentrate with particle size smaller than 38 lm,sulfuric acid concentration150 g L-1,leaching temperature 150℃,leaching time120 min,oxygen partial pressure 0.7 MPa,additive amount of 0.2 wt%.展开更多
The Lanping Basin in the Nujiang-Lancangjiang-Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of l...The Lanping Basin in the Nujiang-Lancangjiang-Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of large unique sediment-hosted Pb-Zn polymetallic deposits or ore districts, such as the Baiyangping ore concentration area which is one of the representative ore district. The Baiyangping ore concentration area can be divided into the east and west ore belts, which were formed in a folded tectogene of the India-Asia continental coUisional setting and was controlled by a large reverse fault. Field observations reveal that the Mesozoic and Cenozoic sedimentary strata were outcropped in the mining area, and that the orebodies are obviously controlled by faults and hosted in sandstone and carbonate rocks. However, the oreforming elements in the east ore belt are mainly Pb-Zn -Sr-Ag, while Pb-Zn-Ag-Cu-Co elements are dominant in the west ore belt. Comparative analysis of the C-O-Sr-S-Pb isotopic compositions suggest that both ore belts had a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata; the ore- forming fluids were originated from formation water and precipitate water, which belonged to basin brine fluid system; sulfur was from organic thermal chemical sulfate reduction and biological sulfate reduction; the metal mineralization material was from sedimentary strata and basement, but the difference of the material source of the basement and the strata and the superimposed mineralization of the west ore belt resulted in the difference of metallogenic elements between the eastern and western metallogenic belts. The Pb-Zn mineralization age of both ore belts was contemporary and formed in the same metaliogenetic event. Both thrust formed at the same time and occurred at the Early Oligocene, which is consistent with the age constrained by field geological relationship.展开更多
The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscop...The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.展开更多
Zinc ferrite is the principal constituent in zinc neutral-leach residue(NLR) which is commonly treated by hot-acid leaching in electrolytic zinc plants. Reductive leaching of zinc ferrite with sphalerite concentrate...Zinc ferrite is the principal constituent in zinc neutral-leach residue(NLR) which is commonly treated by hot-acid leaching in electrolytic zinc plants. Reductive leaching of zinc ferrite with sphalerite concentrate as a reducing agent was performed. It was found that leaching of zinc ferrite in the presence of sphalerit concentrate was a viable process that effectively extracted zinc and indium and converted Fe^3+ into Fe^2+ at the same time. Reflux leaching tests by two stages were performed to achieve extractions of 98.1% for zinc and 97.5% for indium, and a Fe^2+/Fe^3+ molar ratio of 9.6 in leach solution was also obtained. The leaching behaviors of other elements, such as iron, copper and tin were also studied. The results showed that iron and copper were completely leached, whereas tin presented lower extraction values.展开更多
An experiment was carried out to investigate the relative bioavailability of tribasic zinc(Zn) sulfate relative to Zn sulfate for broilers fed a conventional corn-soybean meal diet. A total of 504 1-d-old Arbor Acre...An experiment was carried out to investigate the relative bioavailability of tribasic zinc(Zn) sulfate relative to Zn sulfate for broilers fed a conventional corn-soybean meal diet. A total of 504 1-d-old Arbor Acres commercial male chicks were randomly assigned by body weight of birds to one of seven treatments involving a 2×3 factorial arrangement with three levels of added Zn(30, 60, or 90 mg of Zn kg–1) and two Zn sources(tribasic Zn sulfate and Zn sulfate) plus a control with no added Zn for an experimental phase of 14 d. Plasma Zn, tibia ash Zn, pancreas Zn, and pancreas metallothionein(MT) messenger RNA(m RNA) were analyzed at 6 or 14 d of age post-hatching. The results showed that plasma Zn, tibia ash Zn, pancreas Zn, and pancreas MT m RNA increased linearly(P〈0.002) as dietary Zn concentration increased at 6 or 14 d of age. The R2 for a linear model was greater on d 6 than on d 14 for the above 4 responsive criteria, and among these indices, the fitting of the tibia ash Zn concentration was the best(R2=0.99). Therefore, based on slope ratios from the multiple linear regressions of the above 4 indices of the birds at 6 d of age on daily intake of dietary Zn, the bioavailabilities of tribasic Zn sulfate relative to Zn sulfate(100%) were 95.6%(P=0.18), 83.5%(P=0.01), 87.9%(P=0.53), and 75.9%(P=0.38) for the tibia ash Zn, pancreas Zn, plasma Zn, and pancreas MT m RNA, respectively. The results indicated that generally, Zn from tribasic Zn sulfate was as available as Zn from Zn sulfate for broilers.展开更多
A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine...A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and 95%, respectively. Some harmful impurities that have negative influences on magnetic properties of soft magnetic ferrite material are deeply removed with sulfidization purification and neutral flocculation method. Under the optimum conditions, the content of impurities like Cu, Pb, As, Al in pure Zn-Fe sulfate solution are less than 0.004 g/L, but those of Cd, Si, Ca and Mg are relatively high. Finally, thermal precipitation of iron is carried out at 210 ℃ for 1.5 h. The precipitation ratio of Fe is 93.33%. Compared with the quality standard of ferric oxide for soft magnetic ferrite materials, the contents of Al and Mg in obtained ferric oxide powder meet the requirement of YHT1 level of ferric oxide, and those of Si, Ca meet the requirement of YHT3 level of ferric oxide. XRD and SEM characterizations confirm that the obtained sample is well-dispersed spindle spherule with regular a-Fe2O3 crystal structure. The length-to-diameter ratio ofa-Fe2O3 powder is (3-4):1 with an average particle size of 0.5 μm.展开更多
The early hydration of calcium aluminate cement (CAC) with different kinds of zinc (II),such as ZnSO4g7H2O,ZnO,Zn(NO3)2·6H2O and ZnCl2,was analyzed.Changes in consistency,setting time,hydration heat flow,hydratio...The early hydration of calcium aluminate cement (CAC) with different kinds of zinc (II),such as ZnSO4g7H2O,ZnO,Zn(NO3)2·6H2O and ZnCl2,was analyzed.Changes in consistency,setting time,hydration heat flow,hydration heat amount,ion concentration in solution,and hydration products were found upon the addition of different Zn^2+.The water consumption of standard consistency of CAC is decreased with different Zn^2+.Zn^2+ can delay the initial hydration of CAC.The induction period of cement with Zn^2+ is longer than that of CAC,especially the reaction time of the acceleration period is extended.Zn^2+ can promote hydration hydrate of CAC at 24 h.The characteristic diffraction peaks of CA and CA2 in CAC with different Zn^2+ are significantly reduced.It can inhibit the formation of CAH10 and promote the formation C3AH6 and AH3 in hydration products at 24 h.展开更多
Zinc deficiency is a public health concern and is the most prevalent micronutrient deficiencies in developing countries. The main objective of this study was to assess the prevalence and risk factors of zinc deficienc...Zinc deficiency is a public health concern and is the most prevalent micronutrient deficiencies in developing countries. The main objective of this study was to assess the prevalence and risk factors of zinc deficiency among infants and preschool children. Based on a community, the cross-sectional study was conducted in East Gojjam between October 2011 and April 2012. Two hundred and forty infants and preschool children were randomly selected in the study. Data on potential determinants of zinc deficiency were collected using a structured questionnaire. Serum zinc concentration was measured using atomic absorption spectrometer. Statistical analysis was done using ANOVA, independent sample student's t-test and linear regression model. The mean serum zinc concentration of infants and preschool children was 62.98 (±13.03) μg/dL in 95% confidence interval (CI) between 61.32 and 64.63 (i.e., 95% CI: 61.32, 64.63). About 57,1% of the subjects were zinc deficient. The main determinants of low serum zinc status of infants and preschool children were age and number of family members living on the same land. Zinc status of older children was 3.67 μg/dL (95% CI: -5.58, -1.77) lower than children who were aged 6-10 months. Serum zinc status of infants and preschool children is decreased by 0.83 p.g/dL (95% CI: -1.36, -0.30) with each additional family member. Food insecurity, dietary diversity, sex, child health, anthropometric indices, maternal education and wealth index were not associated with serum zinc status. Zinc deficiency among infants and preschool children is highly prevalent. Such potential deficiencies require urgent attention, including complementary food preparation education, traditional phytate reduction method and family planning implementation recommended in the study area.展开更多
基金Project (50964004) supported by the National Natural Science Foundation of China
文摘The leaching behavior of main metallic sulphides in zinc concentrate under atmospheric oxygen-rich direct leaching conditions was studied through mineralogical analysis. The results show that the sulphides dissolve obviously except pyrite. Based on the relationship between elemental sulfur and the residual sulphides in the leaching residue, the dissolution of sphalerite, chalcopyrite, covellite and galena is assumed to follow the indirect oxidation reactions, where the acidic dissolution takes place firstly and then the released H2S transfers from the mineral surface into bulk solution and is further oxidized into elemental sulfur. The interface chemical reaction is further supposed as the controlling step in the leaching of these sulphides. The direct electrochemical oxidation reactions are assumed to contribute to the dissolution of pyrrhotite, which is controlled by the diffusion through elemental sulfur layer.
基金Project(20050145029)supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(2005221012)supported by Science and Technology Talents Fund for Excellent Youth of Liaoning Province,China
文摘Effects of particle size of the zinc sulfide concentrate,leaching temperature,solid-to-liquid ratio and additive amount on pressure acid leaching process of the zinc sulfide concentrate were studied.The results indicate that the additive can improve the reaction kinetics and the conversion rate.And sulfur can be successfully separated from the zinc sulfide concentrate as elemental sulfur.The reasonable experiment parameters are obtained as follows:the leaching temperature 150℃,oxygen partial pressure 1 MPa,additive amount 1%,solid-to-liquid ratio 1:4,leaching time 2 h,initial sulfuric acid concentration 15%,and particle size less than 44μm.Under the optimum conditions,the leaching rate of the zinc can reach 95%and the reduction rate of the sulfur can reach 90%.
基金supported by the National Basic Research Program of China (No. 2010CB630905)
文摘Zinc concentrate with high gallium content is one of the main resources of gallium.The gallium presents in the form of isomorphism in tetrahedron coordination with sulfur in sphalerite.The research was to investigate the amenability of zinc concentrate with high gallium to pressure oxygen leaching.The particle size,sulfuric acid concentration,oxygen partial pressure,additive amount,and time of reaction were studied.The extraction yields of gallium and zinc are 86%and 98%,respectively.The optimal condition is 100 g of zinc concentrate with particle size smaller than 38 lm,sulfuric acid concentration150 g L-1,leaching temperature 150℃,leaching time120 min,oxygen partial pressure 0.7 MPa,additive amount of 0.2 wt%.
基金granted by the National Natural Science Foundation of China(grants No.41302067,41472067 and 41403043)the Fundamental Research Funds of Chinese Academy of Geological Sciences(grant No.YYWF201614 and 09 program of Institute of Geomechanics)IGCP/SIDA–600,and China Geological Survey(grant No.DD20160053)
文摘The Lanping Basin in the Nujiang-Lancangjiang-Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of large unique sediment-hosted Pb-Zn polymetallic deposits or ore districts, such as the Baiyangping ore concentration area which is one of the representative ore district. The Baiyangping ore concentration area can be divided into the east and west ore belts, which were formed in a folded tectogene of the India-Asia continental coUisional setting and was controlled by a large reverse fault. Field observations reveal that the Mesozoic and Cenozoic sedimentary strata were outcropped in the mining area, and that the orebodies are obviously controlled by faults and hosted in sandstone and carbonate rocks. However, the oreforming elements in the east ore belt are mainly Pb-Zn -Sr-Ag, while Pb-Zn-Ag-Cu-Co elements are dominant in the west ore belt. Comparative analysis of the C-O-Sr-S-Pb isotopic compositions suggest that both ore belts had a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata; the ore- forming fluids were originated from formation water and precipitate water, which belonged to basin brine fluid system; sulfur was from organic thermal chemical sulfate reduction and biological sulfate reduction; the metal mineralization material was from sedimentary strata and basement, but the difference of the material source of the basement and the strata and the superimposed mineralization of the west ore belt resulted in the difference of metallogenic elements between the eastern and western metallogenic belts. The Pb-Zn mineralization age of both ore belts was contemporary and formed in the same metaliogenetic event. Both thrust formed at the same time and occurred at the Early Oligocene, which is consistent with the age constrained by field geological relationship.
基金This work was supported by the National Natural Science Foundation of China(No.20203015 and No.50499335).
文摘The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.
基金Project(2014CB643404)supported by the National Basic Research Program of ChinaProjects(51564030,51474117,51304093,51364022)supported by the National Natural Science Foundation of China+1 种基金Project(0120150070)supported by Yunnan Applied Basic Reach Project,ChinaProject(ZD2014003)supported by the Education Department of Yunnan Province,China
文摘Zinc ferrite is the principal constituent in zinc neutral-leach residue(NLR) which is commonly treated by hot-acid leaching in electrolytic zinc plants. Reductive leaching of zinc ferrite with sphalerite concentrate as a reducing agent was performed. It was found that leaching of zinc ferrite in the presence of sphalerit concentrate was a viable process that effectively extracted zinc and indium and converted Fe^3+ into Fe^2+ at the same time. Reflux leaching tests by two stages were performed to achieve extractions of 98.1% for zinc and 97.5% for indium, and a Fe^2+/Fe^3+ molar ratio of 9.6 in leach solution was also obtained. The leaching behaviors of other elements, such as iron, copper and tin were also studied. The results showed that iron and copper were completely leached, whereas tin presented lower extraction values.
基金support of Changsha Xingjia Bioengineering Co., Ltd.,Chinathe Agricultural Science and Technology Innovation Program, China (ASTIPIAS08)the China Agriculture Research System, China (CARS-42)
文摘An experiment was carried out to investigate the relative bioavailability of tribasic zinc(Zn) sulfate relative to Zn sulfate for broilers fed a conventional corn-soybean meal diet. A total of 504 1-d-old Arbor Acres commercial male chicks were randomly assigned by body weight of birds to one of seven treatments involving a 2×3 factorial arrangement with three levels of added Zn(30, 60, or 90 mg of Zn kg–1) and two Zn sources(tribasic Zn sulfate and Zn sulfate) plus a control with no added Zn for an experimental phase of 14 d. Plasma Zn, tibia ash Zn, pancreas Zn, and pancreas metallothionein(MT) messenger RNA(m RNA) were analyzed at 6 or 14 d of age post-hatching. The results showed that plasma Zn, tibia ash Zn, pancreas Zn, and pancreas MT m RNA increased linearly(P〈0.002) as dietary Zn concentration increased at 6 or 14 d of age. The R2 for a linear model was greater on d 6 than on d 14 for the above 4 responsive criteria, and among these indices, the fitting of the tibia ash Zn concentration was the best(R2=0.99). Therefore, based on slope ratios from the multiple linear regressions of the above 4 indices of the birds at 6 d of age on daily intake of dietary Zn, the bioavailabilities of tribasic Zn sulfate relative to Zn sulfate(100%) were 95.6%(P=0.18), 83.5%(P=0.01), 87.9%(P=0.53), and 75.9%(P=0.38) for the tibia ash Zn, pancreas Zn, plasma Zn, and pancreas MT m RNA, respectively. The results indicated that generally, Zn from tribasic Zn sulfate was as available as Zn from Zn sulfate for broilers.
基金Project(50674104) supported by the National Natural Science Foundation of ChinaProject(2006BA02B04-4-2) supported by the Planned Science and Technology of China
文摘A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and 95%, respectively. Some harmful impurities that have negative influences on magnetic properties of soft magnetic ferrite material are deeply removed with sulfidization purification and neutral flocculation method. Under the optimum conditions, the content of impurities like Cu, Pb, As, Al in pure Zn-Fe sulfate solution are less than 0.004 g/L, but those of Cd, Si, Ca and Mg are relatively high. Finally, thermal precipitation of iron is carried out at 210 ℃ for 1.5 h. The precipitation ratio of Fe is 93.33%. Compared with the quality standard of ferric oxide for soft magnetic ferrite materials, the contents of Al and Mg in obtained ferric oxide powder meet the requirement of YHT1 level of ferric oxide, and those of Si, Ca meet the requirement of YHT3 level of ferric oxide. XRD and SEM characterizations confirm that the obtained sample is well-dispersed spindle spherule with regular a-Fe2O3 crystal structure. The length-to-diameter ratio ofa-Fe2O3 powder is (3-4):1 with an average particle size of 0.5 μm.
基金Funded by National Natural Science Foundation of China(No.51802235)State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of Technology(No.SYSJJ2015-07)。
文摘The early hydration of calcium aluminate cement (CAC) with different kinds of zinc (II),such as ZnSO4g7H2O,ZnO,Zn(NO3)2·6H2O and ZnCl2,was analyzed.Changes in consistency,setting time,hydration heat flow,hydration heat amount,ion concentration in solution,and hydration products were found upon the addition of different Zn^2+.The water consumption of standard consistency of CAC is decreased with different Zn^2+.Zn^2+ can delay the initial hydration of CAC.The induction period of cement with Zn^2+ is longer than that of CAC,especially the reaction time of the acceleration period is extended.Zn^2+ can promote hydration hydrate of CAC at 24 h.The characteristic diffraction peaks of CA and CA2 in CAC with different Zn^2+ are significantly reduced.It can inhibit the formation of CAH10 and promote the formation C3AH6 and AH3 in hydration products at 24 h.
文摘Zinc deficiency is a public health concern and is the most prevalent micronutrient deficiencies in developing countries. The main objective of this study was to assess the prevalence and risk factors of zinc deficiency among infants and preschool children. Based on a community, the cross-sectional study was conducted in East Gojjam between October 2011 and April 2012. Two hundred and forty infants and preschool children were randomly selected in the study. Data on potential determinants of zinc deficiency were collected using a structured questionnaire. Serum zinc concentration was measured using atomic absorption spectrometer. Statistical analysis was done using ANOVA, independent sample student's t-test and linear regression model. The mean serum zinc concentration of infants and preschool children was 62.98 (±13.03) μg/dL in 95% confidence interval (CI) between 61.32 and 64.63 (i.e., 95% CI: 61.32, 64.63). About 57,1% of the subjects were zinc deficient. The main determinants of low serum zinc status of infants and preschool children were age and number of family members living on the same land. Zinc status of older children was 3.67 μg/dL (95% CI: -5.58, -1.77) lower than children who were aged 6-10 months. Serum zinc status of infants and preschool children is decreased by 0.83 p.g/dL (95% CI: -1.36, -0.30) with each additional family member. Food insecurity, dietary diversity, sex, child health, anthropometric indices, maternal education and wealth index were not associated with serum zinc status. Zinc deficiency among infants and preschool children is highly prevalent. Such potential deficiencies require urgent attention, including complementary food preparation education, traditional phytate reduction method and family planning implementation recommended in the study area.
基金supported by the National Natural Science Foundation of China(No.52264026)the Ten Thousand Talent Plans for Young Top-notch Talents of Yunnan Province,China(No.YNWR-QNBJ-2018-051).