The mineralogical characteristics of three kinds of gibbsitic high-iron bauxite and the effects of various digestion conditions on the enrichment and separation of iron minerals were investigated. The results show tha...The mineralogical characteristics of three kinds of gibbsitic high-iron bauxite and the effects of various digestion conditions on the enrichment and separation of iron minerals were investigated. The results show that adding an appropriate organic reductant such as glycerol can promote the digestion of concomitant diaspore, boehmite and alumogoethite as well as the conversion of goethite to hematite in the reductive Bayer digestion. Processing Bauxite A with A/S of 25.41 can directly produce qualified iron concentrates(TFe>56%) by the reductive Bayer digestion, and thus realize the zero red mud discharge. For Bauxite B and Bauxite C with A/S of 7.82 and 3.35, the iron recoveries of 65.13% and 79.13% can be achieved with the corresponding TFe of 52.05% and 50.16% in the iron concentrates by gravity separation, respectively, resulting in the red mud discharge reduction of ~50% or above.展开更多
用采自广东省徐闻县的一个铁铝土剖面研究了不同层次土壤的表面电荷特征及电荷的可变性。结果表明,该剖面C层以下土壤的CEC小于88 mmol kg^-1,土壤游离氧化铁在140.9-220.3 g kg^-1之间,为典型可变电荷土壤。土壤表面正电荷的数量及pH...用采自广东省徐闻县的一个铁铝土剖面研究了不同层次土壤的表面电荷特征及电荷的可变性。结果表明,该剖面C层以下土壤的CEC小于88 mmol kg^-1,土壤游离氧化铁在140.9-220.3 g kg^-1之间,为典型可变电荷土壤。土壤表面正电荷的数量及pH改变一个单位时表面正电荷的变化量均随土壤游离氧化铁含量的增加而增加。当pH〈4.0时,土壤氧化铁对表面负电荷的贡献很小;但有机质的增加会使这一pH范围内土壤表面负电荷的可变性增加。该剖面土壤的PZSE高于PZNC,但两者均随土壤游离氧化铁含量的增加而增大。展开更多
High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit sta...High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit standard for Allitic Udic Ferrisols in China. In this study, a greenhouse experiment was carried out to investigate the effect of antimony(Sb) on biomass, physiological performances,and macro- and micronutrient element concentrations of green Chinese cabbage(Brassica chinensis L.), as well as enzyme activities,in Allitic Udic Ferrisols from Hunan Province, China. Antimony was supplied at rates of 0(control), 2, 5, 10, 20, and 50 mg kg-1and thus with the background value of 1.0 mg kg-1, the Sb concentrations in the treated soil samples were 1, 3, 6, 11 21, and 51 mg kg-1, respectively. The results showed the leaf biomass and ascorbic acid content of cabbage significantly(P < 0.05) decreased by 30.6% and 48.3%, respectively, and soil urease and dehydrogenase activities also significantly(P < 0.05) decreased by 33.6%and 32.5%, respectively, when soil Sb concentration was 21 mg kg-1as compared with the control. The uptake of essential nutrient elements such as Mg, Cu, and Zn by cabbage was obviously affected, while the leaf soluble sugar content slightly changed when the soil Sb concentration exceeded 21 mg kg-1. Based on cabbage physiological responses and soil enzyme activities, the permissible concentration of 21 mg kg-1for Sb in Allitic Udic Ferrisols should be recommended.展开更多
基金Project(2019M652799)supported by China Postdoctoral Science FoundationProject(51604309)supported by the National Natural Science Foundation of China。
文摘The mineralogical characteristics of three kinds of gibbsitic high-iron bauxite and the effects of various digestion conditions on the enrichment and separation of iron minerals were investigated. The results show that adding an appropriate organic reductant such as glycerol can promote the digestion of concomitant diaspore, boehmite and alumogoethite as well as the conversion of goethite to hematite in the reductive Bayer digestion. Processing Bauxite A with A/S of 25.41 can directly produce qualified iron concentrates(TFe>56%) by the reductive Bayer digestion, and thus realize the zero red mud discharge. For Bauxite B and Bauxite C with A/S of 7.82 and 3.35, the iron recoveries of 65.13% and 79.13% can be achieved with the corresponding TFe of 52.05% and 50.16% in the iron concentrates by gravity separation, respectively, resulting in the red mud discharge reduction of ~50% or above.
文摘用采自广东省徐闻县的一个铁铝土剖面研究了不同层次土壤的表面电荷特征及电荷的可变性。结果表明,该剖面C层以下土壤的CEC小于88 mmol kg^-1,土壤游离氧化铁在140.9-220.3 g kg^-1之间,为典型可变电荷土壤。土壤表面正电荷的数量及pH改变一个单位时表面正电荷的变化量均随土壤游离氧化铁含量的增加而增加。当pH〈4.0时,土壤氧化铁对表面负电荷的贡献很小;但有机质的增加会使这一pH范围内土壤表面负电荷的可变性增加。该剖面土壤的PZSE高于PZNC,但两者均随土壤游离氧化铁含量的增加而增大。
基金supported by the National Natural Science Foundation of China(No.41201492)the Science and Technology Project of Changsha City,China(No.K1003056-31)
文摘High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit standard for Allitic Udic Ferrisols in China. In this study, a greenhouse experiment was carried out to investigate the effect of antimony(Sb) on biomass, physiological performances,and macro- and micronutrient element concentrations of green Chinese cabbage(Brassica chinensis L.), as well as enzyme activities,in Allitic Udic Ferrisols from Hunan Province, China. Antimony was supplied at rates of 0(control), 2, 5, 10, 20, and 50 mg kg-1and thus with the background value of 1.0 mg kg-1, the Sb concentrations in the treated soil samples were 1, 3, 6, 11 21, and 51 mg kg-1, respectively. The results showed the leaf biomass and ascorbic acid content of cabbage significantly(P < 0.05) decreased by 30.6% and 48.3%, respectively, and soil urease and dehydrogenase activities also significantly(P < 0.05) decreased by 33.6%and 32.5%, respectively, when soil Sb concentration was 21 mg kg-1as compared with the control. The uptake of essential nutrient elements such as Mg, Cu, and Zn by cabbage was obviously affected, while the leaf soluble sugar content slightly changed when the soil Sb concentration exceeded 21 mg kg-1. Based on cabbage physiological responses and soil enzyme activities, the permissible concentration of 21 mg kg-1for Sb in Allitic Udic Ferrisols should be recommended.
