Red mud is the waste of alumina industry and has high TiO2 and Fe2O3 content which are active components for the adsorption of anion pollutants. In this study, the uptake of phosphate by red mud activated by heat trea...Red mud is the waste of alumina industry and has high TiO2 and Fe2O3 content which are active components for the adsorption of anion pollutants. In this study, the uptake of phosphate by red mud activated by heat treatment and acid-heat treatment was investigated. The factors influencing the adsorption were also investigated. The result showed that the red mud sample treated using acid-heat method at 80℃ with 0.25 mol/L HCl for 2 h achieved the highest phosphate removal. For the heat-activated red mud, the sample heated at 700℃ for 2 h preformed better than the other heat treatment. Phosphate removal by the activated red mud was significantly pH dependent, and pH 7 was the optimal pH for phosphate removal. The adsorption fits Langmuir isotherm model well and the maximum adsorption capacities of the acid-heat activated red mud and the heat activated samples were 202.9 mgP/g and 155.2 mgP/g, respectively.展开更多
It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial...It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash （CFA）, alkaline slag （AS）, red mud （RM） and phosphogypsum （PG） in correcting acidity and aluminum （Al） toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM 〉 AS 〉 CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and AI toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.展开更多
Red mud is the waste generated during aluminum production from bauxite, containing lots of iron and other valuable metals. In order to recover iron from red mud, the technology of adding sodium carbonate—reduction ro...Red mud is the waste generated during aluminum production from bauxite, containing lots of iron and other valuable metals. In order to recover iron from red mud, the technology of adding sodium carbonate—reduction roasting—magnetic separation to treat high-iron red mud was developed. The effects of sodium carbonate dosage, reduction temperature and reduction time on the qualities of final product and the phase transformations in reduction process were discussed in detail. The results showed that the final product (mass percent), assaying Fe of 90.87% and Al2O3 of 0.95% and metallization degree of 94.28% was obtained at an overall iron recovery of 95.76% under the following conditions of adding 8% sodium carbonate, reduction roasting at 1 050 ℃ for 80 min and finally magnetic separation of the reduced pellets by grinding up to 90% passing 0.074 mm at magnetic field intensity of 0.08 T. The XRD (X-ray diffraction) results indicated that the iron oxides were transformed into metallic iron. Most of aluminum mineral and silica mineral reacted with sodium carbonate during the reduction roasting and formed nonmagnetic materials.展开更多
Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） sinc...Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） since the Middle Holocene in the study area. The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods： strong and highly fluctuating during 7.2-4.2 ka BP; moderate and relatively stable during 4.2-1.8 ka BP; and weakened during 1.8-0 ka BP. Compared with the East Asian Summer Monsoon （EASM） recorded in the previous studies, the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM. At the centennial scale, however, the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations （Bond events 0 to 5） within the dating error, most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.展开更多
Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering. In this paper, the current situation of control and prevention of water and mud inrush is summarized and recent a...Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering. In this paper, the current situation of control and prevention of water and mud inrush is summarized and recent advances in relevant theories, grout/equipment, and critical techniques are introduced. The time-variant equations of grout viscosity at different volumetric ratios were obtained based on the constitutive relation of typical fast curing grouts. A large-scale dynamic grouting model testing system （4000 mm × 2000 mm × 5 mm） was developed, and the diffusions of cement and fast curing grouts in dynamic water grouting were investigated. The results reveal that the diffusions of cement grouts and fast curing grouts are U-shaped and asymmetric elliptical, respectively. A multi-parameter real-time monitoring system （＆#981; = 1.5 m, h = 1.2 m） was developed for the grouting process to study the diffusion and reinforcement mechanism of grouting in water-rich faulted zone. A high early strength cream-type reinforcing/plugging grout, a high permeability nano-scale silica gel grout, and a high-expansion filling grout were proposed for the control of water hazards in weak water-rich faulted zone rocks, water inrush in karst passages, and micro-crack water inrush, respectively. Complement technologies and equipment for industrial applications were also proposed. Additionally, a novel full-life periodic dynamic water grouting with the critical grouting borehole as the core was proposed. The key techniques for the control of water inrush in water-rich faulted zone, jointed fissures and karst passages, and micro-crack water inrush were developed.展开更多
A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can ...A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.展开更多
Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to i...Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to indicate the variations of East Asia Winter Monsoon (EAWM), with high (low) content/mean-size of ESGCS denote to strong (weak) EAWM. Combined with AMS14C datings core B2 provides a continuous high-resolution record of EAWM changes over the past 2300 years, with an average resolution of 13 years. The results show that the variations of EAWM are con-sistent with temperature changes inferred from historical documents in eastern China over the past 2300 years, from which four climate stages may be identified. In stages before 1900 aBP (50 AD) and 1450―780 aBP (50―1170 AD) the EAWM were comparatively weak, corresponding to warm climate periods in eastern China, respectively. And in stages of 1900―1450 aBP (50―500 AD) and 780―219 aBP (1170―1731 AD) the EAWM were strongly developed, which correspond well to climate changes of two cold periods in eastern China. It is also shown from this study that the stage at 780―219 aBP (1170―1731 AD) was the coldest climate period during the last 2300 years and could be, therefore, related to the Little Ice Age (LIA). Climatic fluctuations appeared obviously in all the four stages, and two climate events of abrupt changes from warm to cold occurred at around 1900 aBP (50 AD) and 780 aBP (1170 AD), of which the latter is probably related to globe-scale changes of atmospheric circulation at that time.展开更多
In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orth...In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.展开更多
The current recovery technique of Sc was complicated and the chemical consumption was high,This was due to the low content of Sc in resources and the difficulty of stripping.In this research,the isooctanol was added i...The current recovery technique of Sc was complicated and the chemical consumption was high,This was due to the low content of Sc in resources and the difficulty of stripping.In this research,the isooctanol was added into the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester(P507)extraction system to reduce the extraction and improve the stripping of Sc.The maximum stripping ratio of Sc from loaded organic phase by sulfuric acid can increase from 10%(without isooctanol)to 99%(with 15 vol%isooctanol).In the extraction test of the simulated red mud leaching liquor,the separation factors between Sc and Zr,Sc and Ti are 36 and 350,separately.At the same time,other metals are almost not extracted.The high selectivity and stripping of Sc suggest that the P507 with isooctanol extraction system can be applied in the practical Sc recovery process.展开更多
AMS14C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-siz...AMS14C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.展开更多
基金Project supported by the National Natural Science Foundation of China (No.40673003).
文摘Red mud is the waste of alumina industry and has high TiO2 and Fe2O3 content which are active components for the adsorption of anion pollutants. In this study, the uptake of phosphate by red mud activated by heat treatment and acid-heat treatment was investigated. The factors influencing the adsorption were also investigated. The result showed that the red mud sample treated using acid-heat method at 80℃ with 0.25 mol/L HCl for 2 h achieved the highest phosphate removal. For the heat-activated red mud, the sample heated at 700℃ for 2 h preformed better than the other heat treatment. Phosphate removal by the activated red mud was significantly pH dependent, and pH 7 was the optimal pH for phosphate removal. The adsorption fits Langmuir isotherm model well and the maximum adsorption capacities of the acid-heat activated red mud and the heat activated samples were 202.9 mgP/g and 155.2 mgP/g, respectively.
基金Supported by the International Foundation of Science(No.C/4073-1)the National"Eleventh Five Years Plan"Key Project on Science and Technology of China(Nos.2006BAD05B02 and 2009BADC6B02)
文摘It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash （CFA）, alkaline slag （AS）, red mud （RM） and phosphogypsum （PG） in correcting acidity and aluminum （Al） toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM 〉 AS 〉 CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and AI toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.
基金Item Sponsored by Hunan Provincial Innovation Foundation for Postgraduate of China ( CX2011B123 )
文摘Red mud is the waste generated during aluminum production from bauxite, containing lots of iron and other valuable metals. In order to recover iron from red mud, the technology of adding sodium carbonate—reduction roasting—magnetic separation to treat high-iron red mud was developed. The effects of sodium carbonate dosage, reduction temperature and reduction time on the qualities of final product and the phase transformations in reduction process were discussed in detail. The results showed that the final product (mass percent), assaying Fe of 90.87% and Al2O3 of 0.95% and metallization degree of 94.28% was obtained at an overall iron recovery of 95.76% under the following conditions of adding 8% sodium carbonate, reduction roasting at 1 050 ℃ for 80 min and finally magnetic separation of the reduced pellets by grinding up to 90% passing 0.074 mm at magnetic field intensity of 0.08 T. The XRD (X-ray diffraction) results indicated that the iron oxides were transformed into metallic iron. Most of aluminum mineral and silica mineral reacted with sodium carbonate during the reduction roasting and formed nonmagnetic materials.
基金supported by National Basic Research Program of China (Grant No. 2010CB428901)National Natural Science Foundation of China (Grant Nos. 40976036 and40676032)Open Foundation of the State Key Laboratory of Loess and Quaternary Geology (Grant No. SKLLQG1107)
文摘Three cores （ZY-1, ZY-2 and ZY-3） retrieved from the Central Yellow Sea mud （CYSM） were analyzed in sensitive grain size and AMS J4C dating to reconstruct the history of the East Asian Winter Monsoon （EAWM） since the Middle Holocene in the study area. The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods： strong and highly fluctuating during 7.2-4.2 ka BP; moderate and relatively stable during 4.2-1.8 ka BP; and weakened during 1.8-0 ka BP. Compared with the East Asian Summer Monsoon （EASM） recorded in the previous studies, the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM. At the centennial scale, however, the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations （Bond events 0 to 5） within the dating error, most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.
文摘Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering. In this paper, the current situation of control and prevention of water and mud inrush is summarized and recent advances in relevant theories, grout/equipment, and critical techniques are introduced. The time-variant equations of grout viscosity at different volumetric ratios were obtained based on the constitutive relation of typical fast curing grouts. A large-scale dynamic grouting model testing system （4000 mm × 2000 mm × 5 mm） was developed, and the diffusions of cement and fast curing grouts in dynamic water grouting were investigated. The results reveal that the diffusions of cement grouts and fast curing grouts are U-shaped and asymmetric elliptical, respectively. A multi-parameter real-time monitoring system （＆#981; = 1.5 m, h = 1.2 m） was developed for the grouting process to study the diffusion and reinforcement mechanism of grouting in water-rich faulted zone. A high early strength cream-type reinforcing/plugging grout, a high permeability nano-scale silica gel grout, and a high-expansion filling grout were proposed for the control of water hazards in weak water-rich faulted zone rocks, water inrush in karst passages, and micro-crack water inrush, respectively. Complement technologies and equipment for industrial applications were also proposed. Additionally, a novel full-life periodic dynamic water grouting with the critical grouting borehole as the core was proposed. The key techniques for the control of water inrush in water-rich faulted zone, jointed fissures and karst passages, and micro-crack water inrush were developed.
基金Project(21707167)supported by the Natural Science Foundation of China
文摘A feasible approach to selectively recover iron and rare earth elements(REEs)from red mud through acid leaching-coordination-solvent extraction was proposed.The leaching efficiencies of Fe,Al,Ti,Sc,La,Ce,Nd and Y can reach up to 95.9%,82.1%,68.3%,93.3%,82.3%,96.9%,98.3%and 95.6%,respectively,under the optimal condition in the leaching process.Aliquat 336 showed excellent extraction performance of iron in chloride-rich solution,and the maximum extraction efficiency can reach over 96%in one time extraction while the loss of other metals was less than 10%,under the condition of Aliquat 336 concentration(v/v)of 30%,aqueous-organic ratio of 1.0 and extraction time of 20 min.Furthermore,P204 can effectively extract the scandium while Al and most other REEs remain in the aqueous phase.This approach may provide a new insight for the recovery of valuable resources from red mud.
基金supported by the National Natural Science Foundation of China(Grant Nos.90211022 and 40206007)the Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX3-SW-220).
文摘Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to indicate the variations of East Asia Winter Monsoon (EAWM), with high (low) content/mean-size of ESGCS denote to strong (weak) EAWM. Combined with AMS14C datings core B2 provides a continuous high-resolution record of EAWM changes over the past 2300 years, with an average resolution of 13 years. The results show that the variations of EAWM are con-sistent with temperature changes inferred from historical documents in eastern China over the past 2300 years, from which four climate stages may be identified. In stages before 1900 aBP (50 AD) and 1450―780 aBP (50―1170 AD) the EAWM were comparatively weak, corresponding to warm climate periods in eastern China, respectively. And in stages of 1900―1450 aBP (50―500 AD) and 780―219 aBP (1170―1731 AD) the EAWM were strongly developed, which correspond well to climate changes of two cold periods in eastern China. It is also shown from this study that the stage at 780―219 aBP (1170―1731 AD) was the coldest climate period during the last 2300 years and could be, therefore, related to the Little Ice Age (LIA). Climatic fluctuations appeared obviously in all the four stages, and two climate events of abrupt changes from warm to cold occurred at around 1900 aBP (50 AD) and 780 aBP (1170 AD), of which the latter is probably related to globe-scale changes of atmospheric circulation at that time.
基金This work was supported bythe National Basic Research Program(973) of China (Grant No.2003CB415206) andthe National Natural Science Foundation of China (Grant No.50379027 and No.50479004)
文摘In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed.
基金Project supported by the National Basic Research Program of China(2012CBA01202)the National Natural Science Foundation of China(51174184)
文摘The current recovery technique of Sc was complicated and the chemical consumption was high,This was due to the low content of Sc in resources and the difficulty of stripping.In this research,the isooctanol was added into the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester(P507)extraction system to reduce the extraction and improve the stripping of Sc.The maximum stripping ratio of Sc from loaded organic phase by sulfuric acid can increase from 10%(without isooctanol)to 99%(with 15 vol%isooctanol).In the extraction test of the simulated red mud leaching liquor,the separation factors between Sc and Zr,Sc and Ti are 36 and 350,separately.At the same time,other metals are almost not extracted.The high selectivity and stripping of Sc suggest that the P507 with isooctanol extraction system can be applied in the practical Sc recovery process.
基金sponsored by a innovation fund from IOCAS(Grant No.L61022811)the Chinese Academy of Sciences Pilot Project of the National Knowledge Innova-tion Program(Grant No.KZCX3-SW-220).
文摘AMS14C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.
