The ion-adsorption rare earth tailings have become a serious environmental pollution in Southern China, yet the potential of their economical value has not been fully exploited. In this work, the chemical and mineral ...The ion-adsorption rare earth tailings have become a serious environmental pollution in Southern China, yet the potential of their economical value has not been fully exploited. In this work, the chemical and mineral compositions of the ion-adsorption rare earth tailings were characterized by Mineral Liberation Analyze (MLA) and XRF. The results show that 91.98 wt% of the tailings are composed of kaolinite and quartz, latter of which was removed by the sieving method. The other minor minerals contain feldspar, biotite, muscovite, titanomagnetite and limonite. Amongst these, the iron-bearing minerals are mostly found in the titanomagnetite and limonite which can be mostly removed by using a periodic high-gradient magnetic separator with a magnetic induction of 0.6 Tesla. The Fe<sub>2</sub>O<sub>3</sub> content of the tailings changed from 2.11 wt% to 1.06 wt% after the sorting process, which met the Chinese national standard of TC-3 grade raw materials for ceramic industry applications. The Fe<sub>2</sub>O<sub>3</sub> content in kaolinite was further decreased after Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> treatment.展开更多
Several hundred million tons of ion-adsorption rare earth tailings exist in Ganzhou, Southern China, which is a severe environmental hazard. To reduce and reutilize the tailing, kaolinite has been separated from the t...Several hundred million tons of ion-adsorption rare earth tailings exist in Ganzhou, Southern China, which is a severe environmental hazard. To reduce and reutilize the tailing, kaolinite has been separated from the tailings by mechanical separation in laboratory scale and pilot scale. The results show that the tailing is mainly composed of fine kaolinite and coarse quart. Quartz and kaolinite can be separated by sieves, shaker, spiral chute or hydrocyclone, which has the similar results in laboratory scale and pilot scale. 30.2% of the tailings can be re-sourced and applied in ceramic industries. 41.7% of kaolinite can be obtained after sorting and iron removal by magnetic separator in pilot scale, which can be applied in ceramic industries according to the Chinese national standard (TC-3). The results give a progressive solution to re-source the tailings economically.展开更多
A novel bifunctional task-specific ionic liquid(TSIL),i.e.[trialkylmethylammonium][sec-nonylphenoxy acetate]([A336] [CA-100]) was impregnated on intermediate polarized XAD-7 resin,and the prepared solvent impreganated...A novel bifunctional task-specific ionic liquid(TSIL),i.e.[trialkylmethylammonium][sec-nonylphenoxy acetate]([A336] [CA-100]) was impregnated on intermediate polarized XAD-7 resin,and the prepared solvent impreganated resin(SIR) was studied for rare earth(RE) separation.Adsorption ability of the SIR was indicated to be obviously higher than that prepared by [A336][NO3] because of the functional anion of [A336][CA-100].Adsorption kinetics,adsorption isotherm,separation and desorption of the SIR were also stu...展开更多
The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant,which leads to a great difficulty in separation of minerals.In this article,the process of magnetizing roast...The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant,which leads to a great difficulty in separation of minerals.In this article,the process of magnetizing roast and low-intensity magnetic separation was used to recover iron.Effect of calcination temperature,holding time and carbon/oxygen ratio on roasting efficiency was investigated.The parameters evaluating magnetizing roast efficiency and theoretical value were determined.X-ray diffraction(XRD)analysis was used to investigate the conversion of Fe phase after roasting.The results show that the best magnetizing roast conditions are calcination temperature of 650℃,holding time of 2.5 h,and carbon/oxygen molar ratio of 3.85.The best magnetization rate is 2.36,which is close to the theoretical value of 2.33.Based on experiments of low-intensity magnetic separation under different intensities,the best current intensity is 2.0 A to obtain the best separation results.Under the best condition,the concentrate grade of iron is 45.45% and the recovery of iron is 68.36%.Most of rare earth,fluorine,and phosphorus are enriched in the magnetic separation tailings.The XRD analysis shows that Fe exists in Fe2O3 before roasting and exists in Fe3O4after roasting.展开更多
Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage.The ore body structure,pore distribution,pore and throat size,and pore network charac...Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage.The ore body structure,pore distribution,pore and throat size,and pore network characteristics of topsoil,weathered,and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study.The effect of leaching operation on the pore structure was investigated,and main factors affecting the seepage were analyzed.Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores.Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures.Even pore distribution and large size span were observed.Compared with the weathered layer,the topsoil layer demonstrates larger voids,smaller average pore volume and equivalent radius,and fewer coordination throats;however,the average equivalent radius of the throat in the topsoil layer is larger and largescale channels exist through ore body vertically.Hence,permeability of the topsoil layer is significantly higher than that of the weathered layer.Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process.The equivalent radius of the throat is the key to the seepage.Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.展开更多
It is indicated from a study of transport of rare earth ions through the emulsion liquid mem- brane of bis(2,4,4-trimethylpentyl)phosphinic acid-Span 80-toluene that transporting rare earth ions com- pletely and rapid...It is indicated from a study of transport of rare earth ions through the emulsion liquid mem- brane of bis(2,4,4-trimethylpentyl)phosphinic acid-Span 80-toluene that transporting rare earth ions com- pletely and rapidly was realized under the optimum experimental conditions:1.0×10^(-3)~3.0×10^(-3)mol/L bis(2,4,4-trimethylpentyl)phosphinic acid and 2%~4%(W/V)Span 80 in toluene solution as membrane phase,0.50~2.0 mol/L HCl as inner phase,rare earth ion solutions with pH 3.5~5.0 as outer phase.Ac- cording to the differences of transport behavior for rare earth ions,it is possible to separate rare earth ions from mixed solutions of rare earth ions by this liquid membrane system.展开更多
Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and ...Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and composition of rare-earth tailings were investigated. The results show that roast conditions with the temperature of 650 °C, carbon to oxygen ratio of 3.85, and holding time of 2.5 h are in favor of reduction of Fe_2O_3 to Fe_3O_4 when the roasted rare-earth tailings is cooled along with furnace. Under these roast conditions, magnetic susceptibility of rare-earth tailings is 2.36 that is very close to theoretical value(2.33). However, magnetic separation results of iron in rare-earth tailings cooled along with furnace are not satisfactory. Through comparing magnetic separation results of iron in rare-earth tailings cooled by different ways, it is found that water cooling is more favored of magnetic separation of iron in the roasted rare-earth tailings than furnace cooling and air cooling. Grade and recovery of iron in concentrate from rare-earth tailings cooled by water are 45.00%-49.00% and 65.00%-77.50%, respectively.展开更多
The electrodeposition and electrochemical behaviors of rare earths in different ionic liquids are summarized. It is demonstrated that most of the rare earths can be electrodeposited in ionic liquids except cerium. Ani...The electrodeposition and electrochemical behaviors of rare earths in different ionic liquids are summarized. It is demonstrated that most of the rare earths can be electrodeposited in ionic liquids except cerium. Anion of ionic liquids appears to play a significant role in determining the electrochemical windows, and then deciding whether the corresponding ionic liquids can be used for rare earths electrodeposition. The electrochemical behaviors of the reduction process in ionic liquids are similar to those in high-temperature molten salts. The reduction of RE(III) to RE(II) has different reversibility, but the reaction of rare earths to their zerovalent state is irreversible.展开更多
Ce0.85Sm0.15O1.925 (SDC) and La0.9Sr0.1Ga0.5Mg0.2O2.85 (LSGM) were synthesized using Glycine-Nitrate Process (GNP), and the composite electrolytes were prepared by mixing SDC and LSGM. An X-ray diffraction patte...Ce0.85Sm0.15O1.925 (SDC) and La0.9Sr0.1Ga0.5Mg0.2O2.85 (LSGM) were synthesized using Glycine-Nitrate Process (GNP), and the composite electrolytes were prepared by mixing SDC and LSGM. An X-ray diffraction pattern indicated that the mixture of SDC and LSGM consisted of their original phases after heating at 1450 ℃ for 10 h. The electronic conductivity of SDC-LSGM composite electrolytes were measured by direct current polarization method using Hebb-Wagner ion blocking cell at 700-800 ℃ in the oxygen partial pressure range of 104-10-20 MPa and compared with the results of SDC. Typical polarization curves, which were theoretically predicted, were observed on all the samples. The slopes of lgσe-lgPo2 plot for all the composite electrolytes agreed with the theoretically predicted value of-1/4 at some intermediate oxygen partial pressures and -1/6 at low oxygen partial pressure. The electronic conductivity of SDC-LSGM composite electrolytes decreased with the increase in LSGM content, whereas the ionic transport number ti of all the samples increased with the increase in LSGM content.展开更多
A series of compounds, La 2/3- x Li 3 x MoO 4, were first prepared. Their structures are tetragonal scheelites with the cationic defects. The cell parameters a, c and values of c/a decrease with...A series of compounds, La 2/3- x Li 3 x MoO 4, were first prepared. Their structures are tetragonal scheelites with the cationic defects. The cell parameters a, c and values of c/a decrease with the increasing of the substitution amount (3 x ) of lithium ion. Cationic vacancies are getting more as Li + concentration is lower. The diffusion of lithium ion is predominant. The concentration of charge carriers increases with increasing the substitution amount (3 x ) of lithium ion, meanwhile, the concentration of cationic vacancies decreases. The conductivity approaches the best when the substitution amount (3 x ) of lithium ion is about 0.3. The conductivity of La 0.567 Li 0.3 MoO 4 is 6.5×10 -6 S·cm -1 at room temperature.展开更多
The title compound, [Nd(dmso) 7Cl][Bph 4] 2(dmso=dimethylsulfoxide, Bph 4=tetraphenylboron anion) was synthesized in organic solvent acetone/EtOH and the structure was determined by single crystal X ray diffract...The title compound, [Nd(dmso) 7Cl][Bph 4] 2(dmso=dimethylsulfoxide, Bph 4=tetraphenylboron anion) was synthesized in organic solvent acetone/EtOH and the structure was determined by single crystal X ray diffraction. The crystal is triclinic with space group P 1, and the crystal data are as follows: a =1 2554(1) nm, b = 1 2799(1) nm, c =2 4598(3) nm; α =93 53(1)°, β =104 50(1)°, γ =112 77(1)°, V =3 4722(6) nm 3, Z =2, M r=1365 01, D c=1 306 g·cm -3 . The crystal is composed of a big cation [Nd(dmso) 7Cl] 2+ and two big anions [BPh 4] -. The Nd 3+ is coordinated by a chlorine atom and seven oxygen atoms from seven dimethylsulfoxides forming a distorted square antiprism coordination polyhedron,while the BPh - 4 anion is charge equilibrium ion.展开更多
In order to achieve the goal of circular economy and sustainable development of ecological environment,it is important to separate and recover associated elements from rare mineral resources.Compared with traditional ...In order to achieve the goal of circular economy and sustainable development of ecological environment,it is important to separate and recover associated elements from rare mineral resources.Compared with traditional physical and che-mical remediation methods of contaminated soil,phytoremediation is regarded as the most promising green in-situ restoration technology.The purpose of this review is to efctive alleviate the environmental problems caused by rare tailings contaminated soil through phytoremediation and realize the recovery of uranium-thorium,rare earth elements(REEs)and tantalum niobium.This review took rare tailings with uranium-thorium,REEs tantalum-niobium in China as the research object,then the background,significance,mechanisms and applcation strategies of phytoremediation were elaborated.In additon,the cases of spedies with tolerance to uranium thorium,tantalum niobium as well as REEs and their remediation mechanisms were summarized,respectively.Particularly,the typical plants represented by Bras-sica juncea,Sunflower,Phytolacca americana,Dicramopteris dichotoma,Salix SPP,etc,were very efctive in the reme-diation of rare tailings.The infuence factors of phytoremediation eficiency of tailings contaminated soil were discused.Two main factors were the mobility of heavy metals in soil(external cause)and the ennichment ability of species(inter-nal cause).Since the traditional phytoremediation also had some limitations in view of this,the work discussed some auxiliary methods(such as chelaing agents or microbial assisted restoration)to improve the effiency of phytoreme-diation.Finally,the future development of phytoremediation and potential applcation directions were explored.展开更多
The rare earth elements (REE) include the group of 15 lanthanides, scandium and yttrium and have diverse applications in technological and nuclear areas. The existence of REE in massive solid mining wastes generated i...The rare earth elements (REE) include the group of 15 lanthanides, scandium and yttrium and have diverse applications in technological and nuclear areas. The existence of REE in massive solid mining wastes generated in leaching processes of copper minerals in the Atacama region of Chile generates the possibility of creating added value to the treatment of this type of waste and supporting the development of a circular economy, generating a useful by-product in different industries. In order to know the behavior of these elements present in the solid carrier waste, a leaching process was carried out by using two agents separately, corresponding to hydrochloric and nitric acid. The technical feasibility to recover REE from carrier tail was demonstrated, the best leaching agent for these elements being a hydrochloric solution, obtaining a maximum recovery efficiency of 64.5%, for an acid concentration: 3M, temperature: 40<span style="white-space:nowrap;">°</span>C and (liquid/solid) ratio: 4. Lanthanum and cerium present the best individual recoveries compared to the other REE, with a maximum efficiency for a hydrochloric solution of 75.7% and 70.0%, respectively. The interaction of operational parameters that most influence the REE recovery corresponds to the temperature and the (liquid/solid) ratio. After 4 hours of leaching, REE recovery efficiencies remain practically constant. Acid consumptions correspond to 11 (kg HCl/ton mining tail) and 29 (kg HNO<sub>3</sub>/ton mining tail). The highest amount recovery ratios of these elements correspond to 0.355 and 0.224 (kg REE/ton mining tail), for hydrochloric and nitric solutions, respectively. These results influence the types of reagents and parameters to be studied in the following stages of the global process.展开更多
This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca(OH)_2 and NaOH.Roasting experiments ...This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca(OH)_2 and NaOH.Roasting experiments and leaching experiments were carried out to study the decomposition of rare earth minerals.The results indicated that bastnaesite and monazite could be completely decomposed at 650 ℃ and the leaching ratio of rare earths could reach 89.78%.The reaction mechanisms of bastnaesite and monazite at 650 ℃were analyzed.For bastnaesite,both the outer layer decomposition and inner core decomposition occurred simultaneously during the roasting.However,monazite was decomposed in a spatial sequence starting from the outer layer and proceeding to the inner core.展开更多
Common collectors for rare earth mineral(REM) flotation,which include carboxylates and hydroxamates,face problems such as being non-selective and sensitive to impurity ions.A type of ionic liquid(IL),tetraethylammoniu...Common collectors for rare earth mineral(REM) flotation,which include carboxylates and hydroxamates,face problems such as being non-selective and sensitive to impurity ions.A type of ionic liquid(IL),tetraethylammonium mono-(2-ethylhexyl)2-ethylhexyl phosphonate([N_(2222)][EHEHP]),has been investigated previously for rare earth elements(REE) solvent extraction,and was proven to be selective and effective.In this work,[N_(2222)][EHEHP] was evaluated as a collector in bastnasite(a primary REM source for REE production) flotation for the first time.The results were compared with quartz and hematite,two common gangue minerals in REM deposits.Zeta potential measurements and Fouriertransform infrared spectroscopy(FT-IR) were completed to investigate the surface chemical properties involved in the flotation of these minerals using this collector.The findings were compared with microflotation results.FT-IR and zeta potential measurements suggest adsorption of the collector’s phosphonate group onto bastnäsite and hematite,likely through chemisorption;whereas for quartz,the minimum micro flotation recovery is likely due to no adsorption of IL on its surface.Micro flotation re sults show higher collectability of [N_(2222)] [EHEHP] for hematite than bastnasite,the latter only shows appreciable recovery at pH 5 with elevated dosage of IL(500 g/t).To achieve better separation,a two-stage flotation scheme was designed and evaluated by bench scale flotation on a synthetic mineral mixture.The concentrates and tails were analyzed by magnetic separation,and it is found that bastnasite recovery over 90% with maximum upgrade ratio 1.7 can be achieved with elevated collector dosage.展开更多
文摘The ion-adsorption rare earth tailings have become a serious environmental pollution in Southern China, yet the potential of their economical value has not been fully exploited. In this work, the chemical and mineral compositions of the ion-adsorption rare earth tailings were characterized by Mineral Liberation Analyze (MLA) and XRF. The results show that 91.98 wt% of the tailings are composed of kaolinite and quartz, latter of which was removed by the sieving method. The other minor minerals contain feldspar, biotite, muscovite, titanomagnetite and limonite. Amongst these, the iron-bearing minerals are mostly found in the titanomagnetite and limonite which can be mostly removed by using a periodic high-gradient magnetic separator with a magnetic induction of 0.6 Tesla. The Fe<sub>2</sub>O<sub>3</sub> content of the tailings changed from 2.11 wt% to 1.06 wt% after the sorting process, which met the Chinese national standard of TC-3 grade raw materials for ceramic industry applications. The Fe<sub>2</sub>O<sub>3</sub> content in kaolinite was further decreased after Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> treatment.
文摘Several hundred million tons of ion-adsorption rare earth tailings exist in Ganzhou, Southern China, which is a severe environmental hazard. To reduce and reutilize the tailing, kaolinite has been separated from the tailings by mechanical separation in laboratory scale and pilot scale. The results show that the tailing is mainly composed of fine kaolinite and coarse quart. Quartz and kaolinite can be separated by sieves, shaker, spiral chute or hydrocyclone, which has the similar results in laboratory scale and pilot scale. 30.2% of the tailings can be re-sourced and applied in ceramic industries. 41.7% of kaolinite can be obtained after sorting and iron removal by magnetic separator in pilot scale, which can be applied in ceramic industries according to the Chinese national standard (TC-3). The results give a progressive solution to re-source the tailings economically.
基金supported by ‘Hundreds Talents Program’from Chinese Academy of Sciences, National Natural Science Foundation of China (50574080, 20901073)National Key Technology R&D Program of China (2006BAC02A10)Distinguished Young Scholar Foundation of Jilin Province (20060114)
文摘A novel bifunctional task-specific ionic liquid(TSIL),i.e.[trialkylmethylammonium][sec-nonylphenoxy acetate]([A336] [CA-100]) was impregnated on intermediate polarized XAD-7 resin,and the prepared solvent impreganated resin(SIR) was studied for rare earth(RE) separation.Adsorption ability of the SIR was indicated to be obviously higher than that prepared by [A336][NO3] because of the functional anion of [A336][CA-100].Adsorption kinetics,adsorption isotherm,separation and desorption of the SIR were also stu...
基金supported by the Major State Basic Research Development Program of China (No.2012CBA01205)College Foundation of Ministry of Education of China (No.N110502002)National Natural Science Founda- tion of China (Nos. 50934004 and 51274061)
文摘The difference of physicochemical properties among minerals in Baotou rare earth tailings is not significant,which leads to a great difficulty in separation of minerals.In this article,the process of magnetizing roast and low-intensity magnetic separation was used to recover iron.Effect of calcination temperature,holding time and carbon/oxygen ratio on roasting efficiency was investigated.The parameters evaluating magnetizing roast efficiency and theoretical value were determined.X-ray diffraction(XRD)analysis was used to investigate the conversion of Fe phase after roasting.The results show that the best magnetizing roast conditions are calcination temperature of 650℃,holding time of 2.5 h,and carbon/oxygen molar ratio of 3.85.The best magnetization rate is 2.36,which is close to the theoretical value of 2.33.Based on experiments of low-intensity magnetic separation under different intensities,the best current intensity is 2.0 A to obtain the best separation results.Under the best condition,the concentrate grade of iron is 45.45% and the recovery of iron is 68.36%.Most of rare earth,fluorine,and phosphorus are enriched in the magnetic separation tailings.The XRD analysis shows that Fe exists in Fe2O3 before roasting and exists in Fe3O4after roasting.
基金supported by the National Natural Science Foundation of China(Nos.51774153,92062110)National Key Research and Development Program of China(No.2021YFC2901702)。
文摘Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage.The ore body structure,pore distribution,pore and throat size,and pore network characteristics of topsoil,weathered,and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study.The effect of leaching operation on the pore structure was investigated,and main factors affecting the seepage were analyzed.Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores.Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures.Even pore distribution and large size span were observed.Compared with the weathered layer,the topsoil layer demonstrates larger voids,smaller average pore volume and equivalent radius,and fewer coordination throats;however,the average equivalent radius of the throat in the topsoil layer is larger and largescale channels exist through ore body vertically.Hence,permeability of the topsoil layer is significantly higher than that of the weathered layer.Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process.The equivalent radius of the throat is the key to the seepage.Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.
基金Supported by the National Natural Science Foundation of China
文摘It is indicated from a study of transport of rare earth ions through the emulsion liquid mem- brane of bis(2,4,4-trimethylpentyl)phosphinic acid-Span 80-toluene that transporting rare earth ions com- pletely and rapidly was realized under the optimum experimental conditions:1.0×10^(-3)~3.0×10^(-3)mol/L bis(2,4,4-trimethylpentyl)phosphinic acid and 2%~4%(W/V)Span 80 in toluene solution as membrane phase,0.50~2.0 mol/L HCl as inner phase,rare earth ion solutions with pH 3.5~5.0 as outer phase.Ac- cording to the differences of transport behavior for rare earth ions,it is possible to separate rare earth ions from mixed solutions of rare earth ions by this liquid membrane system.
基金Project(2012CBA01205)supported by National Basic Research Program of ChinaProjects(50934004,51274061)supported by the National Natural Science Foundation of ChinaProject(N110502002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and composition of rare-earth tailings were investigated. The results show that roast conditions with the temperature of 650 °C, carbon to oxygen ratio of 3.85, and holding time of 2.5 h are in favor of reduction of Fe_2O_3 to Fe_3O_4 when the roasted rare-earth tailings is cooled along with furnace. Under these roast conditions, magnetic susceptibility of rare-earth tailings is 2.36 that is very close to theoretical value(2.33). However, magnetic separation results of iron in rare-earth tailings cooled along with furnace are not satisfactory. Through comparing magnetic separation results of iron in rare-earth tailings cooled by different ways, it is found that water cooling is more favored of magnetic separation of iron in the roasted rare-earth tailings than furnace cooling and air cooling. Grade and recovery of iron in concentrate from rare-earth tailings cooled by water are 45.00%-49.00% and 65.00%-77.50%, respectively.
基金Funded by National Natural Science Foundation of China (Nos. 50864009 and 50904031)
文摘The electrodeposition and electrochemical behaviors of rare earths in different ionic liquids are summarized. It is demonstrated that most of the rare earths can be electrodeposited in ionic liquids except cerium. Anion of ionic liquids appears to play a significant role in determining the electrochemical windows, and then deciding whether the corresponding ionic liquids can be used for rare earths electrodeposition. The electrochemical behaviors of the reduction process in ionic liquids are similar to those in high-temperature molten salts. The reduction of RE(III) to RE(II) has different reversibility, but the reaction of rare earths to their zerovalent state is irreversible.
基金the National Natural Science Foundation of China (10674034)
文摘Ce0.85Sm0.15O1.925 (SDC) and La0.9Sr0.1Ga0.5Mg0.2O2.85 (LSGM) were synthesized using Glycine-Nitrate Process (GNP), and the composite electrolytes were prepared by mixing SDC and LSGM. An X-ray diffraction pattern indicated that the mixture of SDC and LSGM consisted of their original phases after heating at 1450 ℃ for 10 h. The electronic conductivity of SDC-LSGM composite electrolytes were measured by direct current polarization method using Hebb-Wagner ion blocking cell at 700-800 ℃ in the oxygen partial pressure range of 104-10-20 MPa and compared with the results of SDC. Typical polarization curves, which were theoretically predicted, were observed on all the samples. The slopes of lgσe-lgPo2 plot for all the composite electrolytes agreed with the theoretically predicted value of-1/4 at some intermediate oxygen partial pressures and -1/6 at low oxygen partial pressure. The electronic conductivity of SDC-LSGM composite electrolytes decreased with the increase in LSGM content, whereas the ionic transport number ti of all the samples increased with the increase in LSGM content.
文摘A series of compounds, La 2/3- x Li 3 x MoO 4, were first prepared. Their structures are tetragonal scheelites with the cationic defects. The cell parameters a, c and values of c/a decrease with the increasing of the substitution amount (3 x ) of lithium ion. Cationic vacancies are getting more as Li + concentration is lower. The diffusion of lithium ion is predominant. The concentration of charge carriers increases with increasing the substitution amount (3 x ) of lithium ion, meanwhile, the concentration of cationic vacancies decreases. The conductivity approaches the best when the substitution amount (3 x ) of lithium ion is about 0.3. The conductivity of La 0.567 Li 0.3 MoO 4 is 6.5×10 -6 S·cm -1 at room temperature.
文摘The title compound, [Nd(dmso) 7Cl][Bph 4] 2(dmso=dimethylsulfoxide, Bph 4=tetraphenylboron anion) was synthesized in organic solvent acetone/EtOH and the structure was determined by single crystal X ray diffraction. The crystal is triclinic with space group P 1, and the crystal data are as follows: a =1 2554(1) nm, b = 1 2799(1) nm, c =2 4598(3) nm; α =93 53(1)°, β =104 50(1)°, γ =112 77(1)°, V =3 4722(6) nm 3, Z =2, M r=1365 01, D c=1 306 g·cm -3 . The crystal is composed of a big cation [Nd(dmso) 7Cl] 2+ and two big anions [BPh 4] -. The Nd 3+ is coordinated by a chlorine atom and seven oxygen atoms from seven dimethylsulfoxides forming a distorted square antiprism coordination polyhedron,while the BPh - 4 anion is charge equilibrium ion.
基金This work was supported by the National Natural Science Fund Program(21866006,11875105)General Project of Jiangxi Province Key Research and Development Program(20203BBFL63070,20192BBG70062).
文摘In order to achieve the goal of circular economy and sustainable development of ecological environment,it is important to separate and recover associated elements from rare mineral resources.Compared with traditional physical and che-mical remediation methods of contaminated soil,phytoremediation is regarded as the most promising green in-situ restoration technology.The purpose of this review is to efctive alleviate the environmental problems caused by rare tailings contaminated soil through phytoremediation and realize the recovery of uranium-thorium,rare earth elements(REEs)and tantalum niobium.This review took rare tailings with uranium-thorium,REEs tantalum-niobium in China as the research object,then the background,significance,mechanisms and applcation strategies of phytoremediation were elaborated.In additon,the cases of spedies with tolerance to uranium thorium,tantalum niobium as well as REEs and their remediation mechanisms were summarized,respectively.Particularly,the typical plants represented by Bras-sica juncea,Sunflower,Phytolacca americana,Dicramopteris dichotoma,Salix SPP,etc,were very efctive in the reme-diation of rare tailings.The infuence factors of phytoremediation eficiency of tailings contaminated soil were discused.Two main factors were the mobility of heavy metals in soil(external cause)and the ennichment ability of species(inter-nal cause).Since the traditional phytoremediation also had some limitations in view of this,the work discussed some auxiliary methods(such as chelaing agents or microbial assisted restoration)to improve the effiency of phytoreme-diation.Finally,the future development of phytoremediation and potential applcation directions were explored.
文摘The rare earth elements (REE) include the group of 15 lanthanides, scandium and yttrium and have diverse applications in technological and nuclear areas. The existence of REE in massive solid mining wastes generated in leaching processes of copper minerals in the Atacama region of Chile generates the possibility of creating added value to the treatment of this type of waste and supporting the development of a circular economy, generating a useful by-product in different industries. In order to know the behavior of these elements present in the solid carrier waste, a leaching process was carried out by using two agents separately, corresponding to hydrochloric and nitric acid. The technical feasibility to recover REE from carrier tail was demonstrated, the best leaching agent for these elements being a hydrochloric solution, obtaining a maximum recovery efficiency of 64.5%, for an acid concentration: 3M, temperature: 40<span style="white-space:nowrap;">°</span>C and (liquid/solid) ratio: 4. Lanthanum and cerium present the best individual recoveries compared to the other REE, with a maximum efficiency for a hydrochloric solution of 75.7% and 70.0%, respectively. The interaction of operational parameters that most influence the REE recovery corresponds to the temperature and the (liquid/solid) ratio. After 4 hours of leaching, REE recovery efficiencies remain practically constant. Acid consumptions correspond to 11 (kg HCl/ton mining tail) and 29 (kg HNO<sub>3</sub>/ton mining tail). The highest amount recovery ratios of these elements correspond to 0.355 and 0.224 (kg REE/ton mining tail), for hydrochloric and nitric solutions, respectively. These results influence the types of reagents and parameters to be studied in the following stages of the global process.
基金supported by National Basic Research Program of China(973 Program)(2012CBA01205)
文摘This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca(OH)_2 and NaOH.Roasting experiments and leaching experiments were carried out to study the decomposition of rare earth minerals.The results indicated that bastnaesite and monazite could be completely decomposed at 650 ℃ and the leaching ratio of rare earths could reach 89.78%.The reaction mechanisms of bastnaesite and monazite at 650 ℃were analyzed.For bastnaesite,both the outer layer decomposition and inner core decomposition occurred simultaneously during the roasting.However,monazite was decomposed in a spatial sequence starting from the outer layer and proceeding to the inner core.
基金Project supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)Avalon Advanced Materials Inc.through the Collaborative Research and Development(CRD)Program(CRDPJ 44537-12)。
文摘Common collectors for rare earth mineral(REM) flotation,which include carboxylates and hydroxamates,face problems such as being non-selective and sensitive to impurity ions.A type of ionic liquid(IL),tetraethylammonium mono-(2-ethylhexyl)2-ethylhexyl phosphonate([N_(2222)][EHEHP]),has been investigated previously for rare earth elements(REE) solvent extraction,and was proven to be selective and effective.In this work,[N_(2222)][EHEHP] was evaluated as a collector in bastnasite(a primary REM source for REE production) flotation for the first time.The results were compared with quartz and hematite,two common gangue minerals in REM deposits.Zeta potential measurements and Fouriertransform infrared spectroscopy(FT-IR) were completed to investigate the surface chemical properties involved in the flotation of these minerals using this collector.The findings were compared with microflotation results.FT-IR and zeta potential measurements suggest adsorption of the collector’s phosphonate group onto bastnäsite and hematite,likely through chemisorption;whereas for quartz,the minimum micro flotation recovery is likely due to no adsorption of IL on its surface.Micro flotation re sults show higher collectability of [N_(2222)] [EHEHP] for hematite than bastnasite,the latter only shows appreciable recovery at pH 5 with elevated dosage of IL(500 g/t).To achieve better separation,a two-stage flotation scheme was designed and evaluated by bench scale flotation on a synthetic mineral mixture.The concentrates and tails were analyzed by magnetic separation,and it is found that bastnasite recovery over 90% with maximum upgrade ratio 1.7 can be achieved with elevated collector dosage.