The creep behavior of two PM superalloys,U720Li and RR1000,each alloyed with trace amount of Sc,was systematically investigated.Findings reveal that RR1000 alloy with 0.064 wt.%Sc(R-0.064)demonstrates superior creep r...The creep behavior of two PM superalloys,U720Li and RR1000,each alloyed with trace amount of Sc,was systematically investigated.Findings reveal that RR1000 alloy with 0.064 wt.%Sc(R-0.064)demonstrates superior creep resistance compared to U720Li alloy with 0.043 wt.%Sc(U-0.043),at 650℃ and 1000 MPa,and the primary creep mechanisms in both alloys are identified as dislocation shearing and precipitate bypassing.When tested at 700℃ and 700 MPa,the U-0.043 alloy predominantly exhibits micro-twinning and dislocation bypassing,while the R-0.064 alloy engages in extended stacking fault shearing ofγ'precipitate,dislocation bypassing and climb.At 750℃ and 460 MPa,dislocation bypassing and climb emerge as the main creep mechanisms for both alloys.展开更多
A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particl...A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.展开更多
Based upon the thiophene-2,5-dicarboxylic acid(H_(2)Tdc),a novel[Sc_(3)(μ_(2)-OH)_(3)(CO_(2))_(4)O_(6)]n inorganic chain-based Sc-MOF with decorated nitrate ions,{[Sc_(3)(OH)_(2)(Tdc)_(3)(NO_(3))]⋅H_(2)O}_(∞)(AEU-1;...Based upon the thiophene-2,5-dicarboxylic acid(H_(2)Tdc),a novel[Sc_(3)(μ_(2)-OH)_(3)(CO_(2))_(4)O_(6)]n inorganic chain-based Sc-MOF with decorated nitrate ions,{[Sc_(3)(OH)_(2)(Tdc)_(3)(NO_(3))]⋅H_(2)O}_(∞)(AEU-1;AEU for Army Engineering University of PLA),was synthesized,which shows good water and chemical stabilities.Significantly,due to channel constriction accompanied by the polar window caused by introducing nitrate ions,AEU-1 exhibits high C_(2)H_(6)/C_(2)H_(4)adsorption selectivity comparable to many famous C_(2)H_(6)-selective MOFs,making it a promising candidate for the purification of methanol-to-olefin(MTO)products.Furthermore,theoretical investigations reveal that the introduced nitrate ions in AEU-1 as the main adsorption sites could provide strong interactions between the framework and C2H6/C3H6 in the full-contacting mode,leading to an increase in the adsorption enthalpies(Qst)of C_(2)H_(6)and C_(3)H_(6),and thus further improving the C_(2)H_(6)/C_(2)H_(4)and C_(3)H_(6)/C_(2)H_(4)adsorption selectivity.Our work could open up a new avenue for constructing MOFs with inorganic polar moieties as adsorption sites for one-step C_(2)H_(4)purification and C3H6 recovery from MTO mixtures with high selectivity.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
Red mud is a slimy caustic residue generated from alumina production. Taking into account the rela- tively considerable content and availability of scandium, red mud can be viewed as an important and promising scandiu...Red mud is a slimy caustic residue generated from alumina production. Taking into account the rela- tively considerable content and availability of scandium, red mud can be viewed as an important and promising scandium resource rather than a solid waste. This paper is primarily to review the investigations of scandium recov- ery from red mud based on the most widely used hydrometallurgical processes including acid leaching, sol- vent extraction and ion exchange adsorption. It is thought that recovery of scandium from red mud should be con- sidered as a direct objective rather than a by-product in the development of overall flowsheet. In order to achieve environmentally-friendly processes with high scandium recovery and low cost, more attention is required to be paid to optimizing the selective leaching of scandium to decrease mineral acid consumption and alleviate pollution, and developing new solvent extraction systems and novel ion exchange adsorption materials with high selectivity and recognition for scandium.展开更多
Activated carbon （AC） was modified by tri-butyl phosphate （TBP） for selectively extracting scandium from red mud and characterized by BET （Brunauer-Emmett-Teller） surface area. The modified AC had a preferential...Activated carbon （AC） was modified by tri-butyl phosphate （TBP） for selectively extracting scandium from red mud and characterized by BET （Brunauer-Emmett-Teller） surface area. The modified AC had a preferential adsorption to scandium. The influences of adsorbent dos- age, adsorption temperature, and time on adsorption capacity and selectivity to scandium were examined. An optimum adsorbent dosage （-6.25 g/L）, adsorption temperature （308 K）, and adsorption time （40 min） were figured out. A pseudo-second-order kinetics model was employed for describing the adsorption process of scandium.展开更多
A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste ele...A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.展开更多
Red mud is a byproduct of alumina refining of bauxite ores,and is a significant source for extracting scandium.However,a large amount of iron in red mud makes it difficult to recover scandium because Fe(III) and Sc(Ⅲ...Red mud is a byproduct of alumina refining of bauxite ores,and is a significant source for extracting scandium.However,a large amount of iron in red mud makes it difficult to recover scandium because Fe(III) and Sc(Ⅲ) have similar physicochemical properties.In this study,a new method was developed for selective separation of iron and scandium in acid leachate of red mud using D201 resin.Theoretical calculations indicate that the ferric species mainly exists as FeCl3 or FeCl4-at chloride concentration above 6.65 mol/L,while scandium still exists as SCl2+,making it possible to selectively separate iron fro m scandium through anion resin adso rption.The factors affecting the adso rption of iron and scandium such as chloride conce ntratio n,resin dosage,adso rption time,and temperature were evaluated in batch experiments,The Langmuir model was successfully applied to both iron and scandium adsorption,and the maximum adsorption capacities of iron and scandium are 147.06 and 0.95 mg/g,respectively,indicating a significant difference between iron and scandium.Raman analysis further demonstrates that the iron is adsorbed onto D201 resin as FeCl4 anion.展开更多
Red mud is a bauxite residue generated during the process of alumina production. In this research, the occur- rence mode of scandium in the Bayer red mud was investi- gated mainly by electron probe microanalysis （EPM...Red mud is a bauxite residue generated during the process of alumina production. In this research, the occur- rence mode of scandium in the Bayer red mud was investi- gated mainly by electron probe microanalysis （EPMA）. The Bayer red mud used in this work is composed of 21.47 wt% hematite, 12.13 wt% goethite, 8.86 wt% gibbsite, 5.02 wt% perovskite, 9.70 wt% quartz, 3.23 wt% anhydrite, 29.92 wt% Na_2Al_2Si_5O_14 and 9.67 wt% Al_3Fe_5O_12. Besides, the scandium content in the Bayer red mud is 84.32 × 10-6, indicating that this Bayer red mud is an important scandium resource deserving exploitation. The EPMA results show that the scandium within the Bayer red mud is mainly occurring in the iron minerals of hematite and goethite with the isomorphism form, but its distribution is not homogeneous in these iron minerals with the Sc_2O_3 content between 330 × 10-6 and 2040 × 10-6. This study provides a theoretical base for the further experimental work on the scandium extraction from this Bayer red mud.展开更多
Selective recovery of scandium and titanium from red mud leaching solution was achieved through neutralization precipitation followed by acid leaching approach.In the neutralization precipitation section,the effects o...Selective recovery of scandium and titanium from red mud leaching solution was achieved through neutralization precipitation followed by acid leaching approach.In the neutralization precipitation section,the effects of pH,temperature and reaction time on metal precipitation efficiency were investigated.Under the optimal co ndition,the precipitation efficiencies of scandium and titanium were 93.74%and 99.47%,respectively.In the acid leaching section,the effects of acidity,temperature,reaction time,and raffinate to acid solution ratio on leaching efficiency were investigated.Under the optimal condition,the leaching efficiencies of scandium and titanium were 99.97%and 5.44%,respectively.The loss of scandium and titanium were 6.3%and 5.9%,respectively.Compared with the traditional extraction procedure of scandium in red mud,this method could separate titanium from scandium effectively,which is beneficial for the purification of the products and improvement of value of the metal.展开更多
Scandium (Sc) concentration from the rare earth ore by high gradient magnetic separation (HGMS) was determined on the basis of Sc content, geophysical parameter determination and the magnetic analyses of the ore. Base...Scandium (Sc) concentration from the rare earth ore by high gradient magnetic separation (HGMS) was determined on the basis of Sc content, geophysical parameter determination and the magnetic analyses of the ore. Based on the condition experiments, expanding experiments were carried out. The results showed that the ore had a Sc grade of 48.90 g/t, and after removing iron by low-intensity magnetic separation, a Sc concentrate of 314.89 g/t grade and with 77.53% recovery was obtained by one-stage roughing-one...展开更多
This review article on the development course of scandium solvent extraction covers:(i)neutral phosphorus extractants;(ii)acid phosphorus extractants;(iii)carboxylic acid extractants;(iv)amine extractants;(v)chelating...This review article on the development course of scandium solvent extraction covers:(i)neutral phosphorus extractants;(ii)acid phosphorus extractants;(iii)carboxylic acid extractants;(iv)amine extractants;(v)chelating extractants;(vi)synergistic extractants.Those extractants are of valuable reference for developing new separation process of scandium from red mud,titanium dioride and other rare earth resources.展开更多
An excellent extraction selectivity towards Sc over other REEs in 4 mol/L HCl solution was achieved with the separation factor βSc/REEs over 8000 by 2-ethylhexyl phosphoric acid mono 2-ethylhexyl ester(HEHEHP)and the...An excellent extraction selectivity towards Sc over other REEs in 4 mol/L HCl solution was achieved with the separation factor βSc/REEs over 8000 by 2-ethylhexyl phosphoric acid mono 2-ethylhexyl ester(HEHEHP)and the extraction equilibrium can be obtained within 20 min.The extracted Sc can be stripped using 5 mol/L NaOH solution as eluent at 363 K with the stripping rate of 92.1%obtained.The extraction mechanism was clearly elucidated by slope analysis,saturation extraction,IR,and NMR analysis.It was revealed that the extraction of Sc in 4 mol/L HCl solution is still dominated by cation exchange process between P-O-H and Sc,and coordination process between P=O and Sc,with 6 molecules of extractant as dimer participating in the process.Finally,a flowsheet for the recovery of Sc from ion-adsorption rare earth elements(REEs)concentrate was proposed and proved in lab-scale experiment.展开更多
In this study,we investigated the separation of iron and scandium from Sc-bearing red mud.The red mud object of our study contained 31.11 wt%total iron(TFe),0.0045 wt%Sc,hematite(Fe_(2)O_(3))and ferrosilite(FeO·S...In this study,we investigated the separation of iron and scandium from Sc-bearing red mud.The red mud object of our study contained 31.11 wt%total iron(TFe),0.0045 wt%Sc,hematite(Fe_(2)O_(3))and ferrosilite(FeO·SiO_(2))as the main Fe-bearing minerals.The Sc-bearing red mud was treated by a novel deep reduction roasting and magnetic separation process that includes the addition of coke and CaO to extract Fe and enriching Sc from the Sc-bearing red mud.The addition of coke and CaO enhances the transformation of hematite(Fe_(2)O_(3))to metallic iron(Fe~0)and magnetite(Fe_(3)O_(4))as well as the transformation of ferrosilite into metallic iron(Fe~0).The test results show that utilizing the new process a Fe concentrate with a TFe content of 81.22 wt%and Fe recovery of 92.96%was obtained.Furthermore,magnetic separation tailings with Sc content of 0.0062 wt%and Sc recovery of 98.65%were also obtained.The test results were achieved under the following process conditions:roasting temperature of 1373 K,roasting time of 45 min,calcium oxide dosage of 20 wt%,coke dosage of 25 wt%,grinding fineness of90%<0.04 mm,and magnetic field intensity of 0.24 T.The major minerals in the Fe concentrate are metallic iron(Fe~0)and magnetite(Fe_(3)O_(4)).The main minerals in the magnetic separation tailings with a low TFe content of 2.62%are CaO·SiO_(2),Na_(2)O·SiO_(2),FeO·SiO_(2),Ca_(3)Fe_(2)Si_(3)O_(12),CaAl_(2)SiO_6 and CaFe(SiO_(3))_(2).展开更多
The microstructures of Al-Zn-Mg-Cu-Zr al- loys with minor Sc were studied by using optical microscope（OM）, scanning electron microscope （SEM） and transmission electron microscope（TEM）. The tensile mechanical pro...The microstructures of Al-Zn-Mg-Cu-Zr al- loys with minor Sc were studied by using optical microscope（OM）, scanning electron microscope （SEM） and transmission electron microscope（TEM）. The tensile mechanical properties and electric conductivity of the studied alloys under different treatment conditions were tested. The results show that adding minor Sc can greatly fines the grain size of the Al-Zn-Mg-Cu-Zr alloy ingots and obviously improves the tensile properties and electric conductivity of the alloys. The strengthening mechanism is considered as fine grain strengthening, sub-structure strengthening and dispersion strengthening by Al3 （Sc, Zr）.展开更多
Nowadays 80%of scandium in China is obtained from titanium pigments production waste through a complex purification process.The study mainly focused on the purification of Sc from its concentrate generated from titani...Nowadays 80%of scandium in China is obtained from titanium pigments production waste through a complex purification process.The study mainly focused on the purification of Sc from its concentrate generated from titanium pigments production waste by solvent extraction.Several extractants have been tried and 10%D_(2)EHPA-5%TBP-85%sulfonated kerosene exhibited the best extraction performance towards Sc in 7 mol/L H_(2)SO_(4)solution,so it was selected as the oil phase.0.5%of H_(2)O_(2)was added into the concentrated solution which can effectively inhibit the extraction of Ti.Both the extraction and back extraction parameters are optimized.The preferred extraction conditions were obtained,i.e.,acidity:7 mol/L H_(2)SO_(4),the phase ratio A/O:10,room temperature,mixed contact time:30 min,Sc concentrate:10 g/L,that the extraction rate of Sc in the above conditions was nearly 100%.NaOH was used for back extraction with the stripping rate 99%on the following conditions:5 mol/L NaOH stripping for 30 min at a phase ratio A/O:1 at 90℃.Finally,H_(2)C_(2)O_(4)was used to further purify the back extraction product and Sc_(2)(C_(2)O_(4))_(3)precipitant fo rmed.The final product Sc_(2)O_(3)with a purity over 99.5%was obtained by calcining Sc_(2)(C_(2)O_(4))_(3)at 1000℃for 2 h.A conceptual process for Sc purification was put forward and proved.The total recovery yield of Sc in the whole process is 95%.展开更多
Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycol...Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycolamide(TCHDGA),was synthesized,and the separation performance of scandium from impurity metal ions(Ti,Mn,Ba,Fe,Al and Mg)was investigated,The effects of mixing time,acid concentration and temperature on the scandium extraction were considered.The extraction mechanism was studied by infrared spectroscopy and the Equimole Series Method.Under optimized conditions,the extractant shows a strong affinity to scandium in the nitric acid medium and high extraction separation factors between scandium and these impurity metal ions,A process for the purification of scandium was established.The crude product obtained from titanium white waste acid,95%purity scandium oxide,can be purified to 99.99%after only one step of extraction,scrubbing,and stripping:This technology is economical and straightforward and can realize the high-value recovery of scandium in the titanium white waste acid.展开更多
Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive properties.To address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranula...Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive properties.To address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting,and the effects of minor Sc on mechanical properties,corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically investigated.The results show that the Sc containing alloy has high number density and small size of intragranular precipitates,combined with the solid solution strengthening of Sc and the Al_(3)(Sc_(1-x),Zr_(x))second phase strengthening,the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously enhanced.Meanwhile,the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.展开更多
2,3-Dihydro-2-aryl-4（1H）-quinazolinones were prepared in good yields via condensation of o-aminobenzamide with aldehydes promoted by a catalytic amount of Sc（OTf）3 under mild conditions.
D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl ...D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.展开更多
基金supported by the Natural Science Foundation of China(No.52074366)the Top Ten Science and Technology Projects in Hunan Province,China(No.2024GK1080)+4 种基金the Aero Engine Corporation of China(No.HFZL2022CXY029)the Young Elite Scientists Sponsorship Program by CAST,China(No.2022QNRC001)the Natural Science Foundation of Hunan Province,China(No.2021JJ40757)the Science and Technology Innovation Program of Hunan Province,China(No.2021RC3131)the High Performance Computing Center of Central South University,and the Project supported by State Key Laboratory of Powder Metallurgy,Central South University,China.
文摘The creep behavior of two PM superalloys,U720Li and RR1000,each alloyed with trace amount of Sc,was systematically investigated.Findings reveal that RR1000 alloy with 0.064 wt.%Sc(R-0.064)demonstrates superior creep resistance compared to U720Li alloy with 0.043 wt.%Sc(U-0.043),at 650℃ and 1000 MPa,and the primary creep mechanisms in both alloys are identified as dislocation shearing and precipitate bypassing.When tested at 700℃ and 700 MPa,the U-0.043 alloy predominantly exhibits micro-twinning and dislocation bypassing,while the R-0.064 alloy engages in extended stacking fault shearing ofγ'precipitate,dislocation bypassing and climb.At 750℃ and 460 MPa,dislocation bypassing and climb emerge as the main creep mechanisms for both alloys.
基金Project supported by the National Natural Science Foundation of China (52064002)Guangxi Science and Technology Major Project(AA23073018)。
文摘A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.
基金supported by the Youth Autonomous Innovation Funding from Army Engineering University of PLA(KYJBJKQTZQ23005)the Basic Discipline Incubation Funding from Army Engineering University of PLA(KYJBJKQTZK23011).
文摘Based upon the thiophene-2,5-dicarboxylic acid(H_(2)Tdc),a novel[Sc_(3)(μ_(2)-OH)_(3)(CO_(2))_(4)O_(6)]n inorganic chain-based Sc-MOF with decorated nitrate ions,{[Sc_(3)(OH)_(2)(Tdc)_(3)(NO_(3))]⋅H_(2)O}_(∞)(AEU-1;AEU for Army Engineering University of PLA),was synthesized,which shows good water and chemical stabilities.Significantly,due to channel constriction accompanied by the polar window caused by introducing nitrate ions,AEU-1 exhibits high C_(2)H_(6)/C_(2)H_(4)adsorption selectivity comparable to many famous C_(2)H_(6)-selective MOFs,making it a promising candidate for the purification of methanol-to-olefin(MTO)products.Furthermore,theoretical investigations reveal that the introduced nitrate ions in AEU-1 as the main adsorption sites could provide strong interactions between the framework and C2H6/C3H6 in the full-contacting mode,leading to an increase in the adsorption enthalpies(Qst)of C_(2)H_(6)and C_(3)H_(6),and thus further improving the C_(2)H_(6)/C_(2)H_(4)and C_(3)H_(6)/C_(2)H_(4)adsorption selectivity.Our work could open up a new avenue for constructing MOFs with inorganic polar moieties as adsorption sites for one-step C_(2)H_(4)purification and C3H6 recovery from MTO mixtures with high selectivity.
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financially supported by the National Natural Science Foundation of China (Nos. 51234008 and 51574024)the China Postdoctoral Science Foundation (No. 2016M590046)
文摘Red mud is a slimy caustic residue generated from alumina production. Taking into account the rela- tively considerable content and availability of scandium, red mud can be viewed as an important and promising scandium resource rather than a solid waste. This paper is primarily to review the investigations of scandium recov- ery from red mud based on the most widely used hydrometallurgical processes including acid leaching, sol- vent extraction and ion exchange adsorption. It is thought that recovery of scandium from red mud should be con- sidered as a direct objective rather than a by-product in the development of overall flowsheet. In order to achieve environmentally-friendly processes with high scandium recovery and low cost, more attention is required to be paid to optimizing the selective leaching of scandium to decrease mineral acid consumption and alleviate pollution, and developing new solvent extraction systems and novel ion exchange adsorption materials with high selectivity and recognition for scandium.
文摘Activated carbon （AC） was modified by tri-butyl phosphate （TBP） for selectively extracting scandium from red mud and characterized by BET （Brunauer-Emmett-Teller） surface area. The modified AC had a preferential adsorption to scandium. The influences of adsorbent dos- age, adsorption temperature, and time on adsorption capacity and selectivity to scandium were examined. An optimum adsorbent dosage （-6.25 g/L）, adsorption temperature （308 K）, and adsorption time （40 min） were figured out. A pseudo-second-order kinetics model was employed for describing the adsorption process of scandium.
文摘A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.
基金Project supported by the Natural National Science Foundation of China(21707167)。
文摘Red mud is a byproduct of alumina refining of bauxite ores,and is a significant source for extracting scandium.However,a large amount of iron in red mud makes it difficult to recover scandium because Fe(III) and Sc(Ⅲ) have similar physicochemical properties.In this study,a new method was developed for selective separation of iron and scandium in acid leachate of red mud using D201 resin.Theoretical calculations indicate that the ferric species mainly exists as FeCl3 or FeCl4-at chloride concentration above 6.65 mol/L,while scandium still exists as SCl2+,making it possible to selectively separate iron fro m scandium through anion resin adso rption.The factors affecting the adso rption of iron and scandium such as chloride conce ntratio n,resin dosage,adso rption time,and temperature were evaluated in batch experiments,The Langmuir model was successfully applied to both iron and scandium adsorption,and the maximum adsorption capacities of iron and scandium are 147.06 and 0.95 mg/g,respectively,indicating a significant difference between iron and scandium.Raman analysis further demonstrates that the iron is adsorbed onto D201 resin as FeCl4 anion.
基金supported by the National Natural Science Foundation of China (Nos. 51604026 and 51234008)the China Postdoctoral Science Foundation (Nos. 2016M590046 and 2016T90034)
文摘Red mud is a bauxite residue generated during the process of alumina production. In this research, the occur- rence mode of scandium in the Bayer red mud was investi- gated mainly by electron probe microanalysis （EPMA）. The Bayer red mud used in this work is composed of 21.47 wt% hematite, 12.13 wt% goethite, 8.86 wt% gibbsite, 5.02 wt% perovskite, 9.70 wt% quartz, 3.23 wt% anhydrite, 29.92 wt% Na_2Al_2Si_5O_14 and 9.67 wt% Al_3Fe_5O_12. Besides, the scandium content in the Bayer red mud is 84.32 × 10-6, indicating that this Bayer red mud is an important scandium resource deserving exploitation. The EPMA results show that the scandium within the Bayer red mud is mainly occurring in the iron minerals of hematite and goethite with the isomorphism form, but its distribution is not homogeneous in these iron minerals with the Sc_2O_3 content between 330 × 10-6 and 2040 × 10-6. This study provides a theoretical base for the further experimental work on the scandium extraction from this Bayer red mud.
基金Project supported by the National Natural Science Foundation of China(21707167)。
文摘Selective recovery of scandium and titanium from red mud leaching solution was achieved through neutralization precipitation followed by acid leaching approach.In the neutralization precipitation section,the effects of pH,temperature and reaction time on metal precipitation efficiency were investigated.Under the optimal co ndition,the precipitation efficiencies of scandium and titanium were 93.74%and 99.47%,respectively.In the acid leaching section,the effects of acidity,temperature,reaction time,and raffinate to acid solution ratio on leaching efficiency were investigated.Under the optimal condition,the leaching efficiencies of scandium and titanium were 99.97%and 5.44%,respectively.The loss of scandium and titanium were 6.3%and 5.9%,respectively.Compared with the traditional extraction procedure of scandium in red mud,this method could separate titanium from scandium effectively,which is beneficial for the purification of the products and improvement of value of the metal.
文摘Scandium (Sc) concentration from the rare earth ore by high gradient magnetic separation (HGMS) was determined on the basis of Sc content, geophysical parameter determination and the magnetic analyses of the ore. Based on the condition experiments, expanding experiments were carried out. The results showed that the ore had a Sc grade of 48.90 g/t, and after removing iron by low-intensity magnetic separation, a Sc concentrate of 314.89 g/t grade and with 77.53% recovery was obtained by one-stage roughing-one...
基金Project supported by the National Basic Research Program of China(973 Project,2006CB403302)。
文摘This review article on the development course of scandium solvent extraction covers:(i)neutral phosphorus extractants;(ii)acid phosphorus extractants;(iii)carboxylic acid extractants;(iv)amine extractants;(v)chelating extractants;(vi)synergistic extractants.Those extractants are of valuable reference for developing new separation process of scandium from red mud,titanium dioride and other rare earth resources.
基金Projects(11705032,11975082,U1967218)supported by the National Natural Science Foundation of ChinaProject(2017GXNSFBA198175)supported by the Natural Science Foundation of Guangxi Province,ChinaProject(AA17204100)supported by the Science and Technology Major Project of Guangxi Province,China。
文摘An excellent extraction selectivity towards Sc over other REEs in 4 mol/L HCl solution was achieved with the separation factor βSc/REEs over 8000 by 2-ethylhexyl phosphoric acid mono 2-ethylhexyl ester(HEHEHP)and the extraction equilibrium can be obtained within 20 min.The extracted Sc can be stripped using 5 mol/L NaOH solution as eluent at 363 K with the stripping rate of 92.1%obtained.The extraction mechanism was clearly elucidated by slope analysis,saturation extraction,IR,and NMR analysis.It was revealed that the extraction of Sc in 4 mol/L HCl solution is still dominated by cation exchange process between P-O-H and Sc,and coordination process between P=O and Sc,with 6 molecules of extractant as dimer participating in the process.Finally,a flowsheet for the recovery of Sc from ion-adsorption rare earth elements(REEs)concentrate was proposed and proved in lab-scale experiment.
基金Project supported by the Sichuan Science and Technology Program(2022YFS0462,2021YJ0057,2021YFG0268)the China Postdoctoral Science Foundation(2014M560734)。
文摘In this study,we investigated the separation of iron and scandium from Sc-bearing red mud.The red mud object of our study contained 31.11 wt%total iron(TFe),0.0045 wt%Sc,hematite(Fe_(2)O_(3))and ferrosilite(FeO·SiO_(2))as the main Fe-bearing minerals.The Sc-bearing red mud was treated by a novel deep reduction roasting and magnetic separation process that includes the addition of coke and CaO to extract Fe and enriching Sc from the Sc-bearing red mud.The addition of coke and CaO enhances the transformation of hematite(Fe_(2)O_(3))to metallic iron(Fe~0)and magnetite(Fe_(3)O_(4))as well as the transformation of ferrosilite into metallic iron(Fe~0).The test results show that utilizing the new process a Fe concentrate with a TFe content of 81.22 wt%and Fe recovery of 92.96%was obtained.Furthermore,magnetic separation tailings with Sc content of 0.0062 wt%and Sc recovery of 98.65%were also obtained.The test results were achieved under the following process conditions:roasting temperature of 1373 K,roasting time of 45 min,calcium oxide dosage of 20 wt%,coke dosage of 25 wt%,grinding fineness of90%<0.04 mm,and magnetic field intensity of 0.24 T.The major minerals in the Fe concentrate are metallic iron(Fe~0)and magnetite(Fe_(3)O_(4)).The main minerals in the magnetic separation tailings with a low TFe content of 2.62%are CaO·SiO_(2),Na_(2)O·SiO_(2),FeO·SiO_(2),Ca_(3)Fe_(2)Si_(3)O_(12),CaAl_(2)SiO_6 and CaFe(SiO_(3))_(2).
文摘The microstructures of Al-Zn-Mg-Cu-Zr al- loys with minor Sc were studied by using optical microscope（OM）, scanning electron microscope （SEM） and transmission electron microscope（TEM）. The tensile mechanical properties and electric conductivity of the studied alloys under different treatment conditions were tested. The results show that adding minor Sc can greatly fines the grain size of the Al-Zn-Mg-Cu-Zr alloy ingots and obviously improves the tensile properties and electric conductivity of the alloys. The strengthening mechanism is considered as fine grain strengthening, sub-structure strengthening and dispersion strengthening by Al3 （Sc, Zr）.
基金the National Natural Science Foundation of China(11705032,11675102)Natural Science Foundation of Guangxi Province(2017GXNSFBA198175)Science and Technology Major Project of Guangxi Province(AA17204100)。
文摘Nowadays 80%of scandium in China is obtained from titanium pigments production waste through a complex purification process.The study mainly focused on the purification of Sc from its concentrate generated from titanium pigments production waste by solvent extraction.Several extractants have been tried and 10%D_(2)EHPA-5%TBP-85%sulfonated kerosene exhibited the best extraction performance towards Sc in 7 mol/L H_(2)SO_(4)solution,so it was selected as the oil phase.0.5%of H_(2)O_(2)was added into the concentrated solution which can effectively inhibit the extraction of Ti.Both the extraction and back extraction parameters are optimized.The preferred extraction conditions were obtained,i.e.,acidity:7 mol/L H_(2)SO_(4),the phase ratio A/O:10,room temperature,mixed contact time:30 min,Sc concentrate:10 g/L,that the extraction rate of Sc in the above conditions was nearly 100%.NaOH was used for back extraction with the stripping rate 99%on the following conditions:5 mol/L NaOH stripping for 30 min at a phase ratio A/O:1 at 90℃.Finally,H_(2)C_(2)O_(4)was used to further purify the back extraction product and Sc_(2)(C_(2)O_(4))_(3)precipitant fo rmed.The final product Sc_(2)O_(3)with a purity over 99.5%was obtained by calcining Sc_(2)(C_(2)O_(4))_(3)at 1000℃for 2 h.A conceptual process for Sc purification was put forward and proved.The total recovery yield of Sc in the whole process is 95%.
基金supported by the National Natural Science Foundation of China(21876062)。
文摘Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycolamide(TCHDGA),was synthesized,and the separation performance of scandium from impurity metal ions(Ti,Mn,Ba,Fe,Al and Mg)was investigated,The effects of mixing time,acid concentration and temperature on the scandium extraction were considered.The extraction mechanism was studied by infrared spectroscopy and the Equimole Series Method.Under optimized conditions,the extractant shows a strong affinity to scandium in the nitric acid medium and high extraction separation factors between scandium and these impurity metal ions,A process for the purification of scandium was established.The crude product obtained from titanium white waste acid,95%purity scandium oxide,can be purified to 99.99%after only one step of extraction,scrubbing,and stripping:This technology is economical and straightforward and can realize the high-value recovery of scandium in the titanium white waste acid.
基金Project supported by the National Natural Science Foundation of China (51971019,51571013)。
文摘Nowadays,it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive properties.To address this,the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting,and the effects of minor Sc on mechanical properties,corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically investigated.The results show that the Sc containing alloy has high number density and small size of intragranular precipitates,combined with the solid solution strengthening of Sc and the Al_(3)(Sc_(1-x),Zr_(x))second phase strengthening,the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously enhanced.Meanwhile,the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.
基金We are grateful to the National Basic Research Program （No. 2003CB114402）；the National Natural Science Foundation of China （Nos. 20476098 and 20676123） ；Wenzhou University Post-graduate Innovation Foundation （No. YCX0515） for financial support.
文摘2,3-Dihydro-2-aryl-4（1H）-quinazolinones were prepared in good yields via condensation of o-aminobenzamide with aldehydes promoted by a catalytic amount of Sc（OTf）3 under mild conditions.
基金Projects(51904097,51804103)supported by the National Natural Science Foundation of ChinaProject(2019GGJS056)supported by the Training Program for Young Backbone Teachers in Colleges and Universities of Henan Province,China+2 种基金Project(HB201905)supported by Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,ChinaProject(202102310548)supported by Scientific and Technological Project of Henan Province,ChinaProject(21IRTSTHN006)supported by Program for Innovative Research Team in the University of Henan Province,China。
文摘D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.
