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Flotation and adsorption of novel Gemini decyl-bishydroxamic acid on bastnaesite:Experiments and density functional theory calculations
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作者 Longhua Xu Chang Liu +5 位作者 Jiushuai Deng Donghui Wang Kai Xue Yan Wang Jinping Meng Jiongtian Liu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第10期1193-1202,共10页
Rare earth element is an important strategic metal,but the supply of high purity rare earth ores is growing slowly,which is in sharp contradiction with the rapidly growing demand.Froth flotation has been confirmed to ... Rare earth element is an important strategic metal,but the supply of high purity rare earth ores is growing slowly,which is in sharp contradiction with the rapidly growing demand.Froth flotation has been confirmed to be an effective method to separate bastnaesite from its gangue minerls.However,the traditional collectors are facing serious problems in flotation separation of minerals,requiring the addition of excess depressant and regulator in the flotation process.Herein,we proposed and synthesized novel Gemini hydroxamic acids Octyl-bishydroxamic acid(OTBHA),Decyl-bishydroxamic acid(DCBHA)and Dodecyl-bishydroxamic acid(DDBHA)as the collectors in bastnaesite-barite flotation system.The effect of different carbon chain lengths on the molecular properties were explored by density functional theory(DFT)calculations.DCBHA possessed a stronger reactivity compared with OCBHA and DDBHA.The flotation results verified the consistency of the computational calculation about the performance prediction of Gemini hydroxamic acids.Compared with OCBHA and DDBHA,DCBHA displayed superior collecting affinity toward bastnaesite,and did not float barite.Zeta potential results showed that the presence of DCBHA increased the potential of bastnaesite,while it had almost no effect on barite,indicating DCBHA had a stronger affinity for bastnaesite.Then,Fourier transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analyses indicated that the adsorption mechanism was due to two hydroxamate groups of DCBHA co-anchored on bastnaesite surface by forming five-membered hydroxamic―(O―O)―Ce complexes.In addition,atomic force microscopy(AFM)clearly observed that DCBHA uniformly aggregated on bastnaesite surface,which increased surface contact angle and improved the hydrophobicity of bastnaesite. 展开更多
关键词 Gemini-hydroxamic acid bastnaesite DFT FLOTATION Adsorption mechanism
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Kinetics of rare earth leaching from roasted ore of bastnaesite with sulfuric acid 被引量:9
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作者 冯兴亮 龙志奇 +3 位作者 崔大立 王良士 黄小卫 张国成 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第3期849-854,共6页
Sulfuric acid leaching process was applied to extracting rare earth(RE) from roasted ore of Dechang bastnaesite in Sichuan,China.The effect of particle size,stirring speed,sulfuric acid concentration and leaching te... Sulfuric acid leaching process was applied to extracting rare earth(RE) from roasted ore of Dechang bastnaesite in Sichuan,China.The effect of particle size,stirring speed,sulfuric acid concentration and leaching temperature on RE extraction efficiency was investigated,and the leaching kinetics of RE was analyzed.Under selected leaching conditions,including particle size(0.074-0.100 mm),sulfuric acid concentration 1.50 mol/L,mass ratio of liquid to solid 8 and stirring speed 500 r/min,the leaching kinetics analysis shows that the reaction rate of leaching process is controlled by diffusion through the product/ash layer which can be described by the shrinking-core model,and the calculated activation energy of 9.977 kJ/mol is characteristic for a diffusion-controlled process. 展开更多
关键词 bastnaesite rare earth roasting ore LEACHING KINETICS
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Leaching kinetics of bastnaesite concentrate in HCl solution 被引量:12
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作者 边雪 尹少华 +1 位作者 罗瑶 吴文远 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第10期2306-2310,共5页
The leaching kinetics of bastnaesite concentrate in HCl solution was investigated with respect to the effects of HCl concentration by changing HCl concentration,leaching temperature,liquid to solid ratio,and particle ... The leaching kinetics of bastnaesite concentrate in HCl solution was investigated with respect to the effects of HCl concentration by changing HCl concentration,leaching temperature,liquid to solid ratio,and particle size.A particle size of 25 μm was required to leach 89.6% RE2(CO3)3 and 1.5%REF3 at 90 ℃ for 90 min,when HCl concentration was 6 mol/L and liquid to solid ratio was 15:1.The leaching kinetics of bastnaesite concentrate is represented by shrinking core model with diffusion through a porous product layer.The activation energies for the dissolution reaction of RE2(CO3)3 and REF3 were calculated to be 59.39 kJ/mol and 66.13 kJ/mol respectively. 展开更多
关键词 bastnaesite RE2(CO3)3 REF3 leaching kinetics
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Compositional Variations and Its Implications of a Bastnaesite Crystal,Mianning County,Sichuan Province 被引量:1
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作者 吴澄宇 袁忠信 +3 位作者 白鸽 安庆骧 王锐兵 邓赛文 《Journal of Rare Earths》 SCIE EI CAS CSCD 1997年第1期2-6,共5页
A bastnaesite crystal about 12×20 mm 2 in size collected from a pegmatitic aegirine augite barite bastnaesite vein of the Maoniuping rare earth deposit, Mianning County, Sichuan Province, has been analyzed for... A bastnaesite crystal about 12×20 mm 2 in size collected from a pegmatitic aegirine augite barite bastnaesite vein of the Maoniuping rare earth deposit, Mianning County, Sichuan Province, has been analyzed for La, Ce, Pr and Nd by synchronous radiative X ray fluorescence(SRXRF) technics at the National BEPC Laboratory. The results show an apparent compositional variation along vertical and horizontal sections accross the crystal which may be divided into three compositional zones(A, B and C). Significant difference exists between the inner portion(zone A), averaging at 28 35% La 2O 3, 35 04% CeO 2, 2 01% Pr 6O 11 and 5 44% Nd 2O 3, and the outer portion(zone B), averaging at 32 81% La 2O 3, 42 26% CeO 2 3 30% Pr 6O 11 and 7 08%. Nd 2O 3, of the crystal. Only one analysis is available on the egde of the crystal(zone C) yielding 14 50% La 2O 3, 21 41% CeO 2, 4 19% Pr 6O 11 and 16 71% Nd 2O 3, which demonstrates probably fractionations between LREE and HREE. The La/Ce ratio, however, is nearly constant around 0 84±0 08 among the three zones, while the La/Pr and La/Nd ratios erratically fluctuate due to low and variable contents of Pr and Nd. These results indicate that the REE bearing hydrothermal system underwent a significant compositional change during the stepwise growth of the bastnaesite crystal. 展开更多
关键词 Rare earths bastnaesite Crystal chemistry South West China
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FLOTATION BEHAVIOUR AND MECHANISM OF BASTNAESITE WITH N-HYDROXYL PHTHALICIMIDE
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作者 REN Jun Baotou Research Institute of Rare Earth Metals,Ministry of Metallurgical Industry,Baotou,China engineer,Baotou Research Institute of Rare Earth Metals,Baotou 014010,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1993年第12期432-436,共5页
The flotation behaviour and mechanism of bastnaesite with N-hydroxyl phthalicimide were investigated by ξ-potential measurement,infrared spectrum and quantum chemistry calculation.The results show that 3 oxygen atoms... The flotation behaviour and mechanism of bastnaesite with N-hydroxyl phthalicimide were investigated by ξ-potential measurement,infrared spectrum and quantum chemistry calculation.The results show that 3 oxygen atoms from N-hydroxyl phthalicirnide chelate the rare earth ions on the surface of bastnaesite to form double five-chain O=C-N-O- RE(Ⅲ)-O chelate which is chemically adsorbed on the surface of bastnasite,thus making N-hydroxyl phthalicimide an effective collector for bastnaesite. 展开更多
关键词 N-hydroxyl phthalicimide FLOTATION bastnaesite COLLECTOR
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Stepwise Chlorination-Chemical Vapor Transport Reactions for Bastnaesite Concentrate
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作者 张丽清 王军 +2 位作者 范世华 雷鹏翔 王之昌 《Journal of Rare Earths》 SCIE EI CAS CSCD 2002年第1期56-60,共5页
Vapor phase extraction and mutual separation of rare earth (RE) elements from bastnaesite concentrate were investigated using stepwise chlorination chemical vapor transport reactions mediated by vapor complexes LnAl ... Vapor phase extraction and mutual separation of rare earth (RE) elements from bastnaesite concentrate were investigated using stepwise chlorination chemical vapor transport reactions mediated by vapor complexes LnAl n Cl 3 n +3 (Ln=RE elements). The bastnaesite was heated to 800 K and chlorinated between 800~1300 K with C+Cl 2+SiCl 4 to remove CO 2, SiF 4 and high volatile chlorides. At the temperature of 1300 K for 6 h, the resulted RE chlorides were chemically transported and mutual separated with the vapor complexes while CaCl 2 and BaCl 2 were remained in the residues. Significantly different CVT characteristics were observed for gradually decreased and wave form temperature gradients. 展开更多
关键词 rare earths bastnaesite concentrate chemical vapor transport RE vapor complexes LnAl n Cl 3 n +3
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Scanning Analysis of REE in Bastnaesite with Synchrotron Radiation X-Ray Fluorescence Microprobe
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作者 安庆骧 王锐兵 +3 位作者 邓赛文 潘巨祥 吴应荣 吴澄宇 《Journal of Rare Earths》 SCIE EI CAS CSCD 1996年第4期308-311,共4页
The content of REE(La.Ce.Pr.Nd.Sm) in bastnaesite was measured by synchrotron radiation X-ray fluorescence microprobe.Scanning analysis makes use of excitation of the REE K lines between 33 and 50 keV.SR white beam fr... The content of REE(La.Ce.Pr.Nd.Sm) in bastnaesite was measured by synchrotron radiation X-ray fluorescence microprobe.Scanning analysis makes use of excitation of the REE K lines between 33 and 50 keV.SR white beam from a Wiggler source at the Beijing Electron Positron Collider(BEPC) of the National Laboratory,in order to excite the REE.The bastnaesite from the same mineral area was powdered to particle size≤300 mesh.It was then divided into two parts.One portion was used to be determined by XRF after depositing with oxalate and transforming into oxide.The other was pressed into disk without any binder as the reference sample.The weight and the diamieter of the disk were 15 g and 26 mm respectively. 展开更多
关键词 Synchrotron radiation X-ray fluomcence Rare earth analysis bastnaesite
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Utilizing N-hydroxy-9-octadecenamide as a collector in flotation separation of bastnaesite and fluorite 被引量:1
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作者 Zhihao Guo Sultan Ahmed Khoso +1 位作者 Mengjie Tian Wei Sun 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第8期1620-1628,I0008,共10页
Bastnaesite((Ce,La,Pr,Nd)CO_(3)F) is a significant light rare earth mineral found in nature,known for its fine-grained properties.Flotation is commonly employed for the recovery of fine-grained bastnaesite particles.C... Bastnaesite((Ce,La,Pr,Nd)CO_(3)F) is a significant light rare earth mineral found in nature,known for its fine-grained properties.Flotation is commonly employed for the recovery of fine-grained bastnaesite particles.Collectors serve as an essential flotation reagent that enhance the surface hydrophobicity of target minerals.A novel collector,N-hydroxy-9-octadecenamide(N-OH-9-ODA),was synthesised in this study.N-OH-9-ODA exhibits superior selectivity compared to the traditional collector oleic acid in the flotation separation of bastnaesite and fluorite.The experimental and co mputational results indicate that N-OH-9-ODA exhibits superior selectivity due to its higher adsorption affinity for bastnaesite surface compared to fluorite surface.The zeta potential and the binding energies of the Ce 3d peaks in the X-ray photoelectron spectrum(XPS) of bastnaesite surface exhibit significant shifts.Conversely,fluorite surface demonstrates minimal alterations in its zeta potential and the binding energies of the Ca 2p peaks in its XPS after its interaction with N-OH-9-ODA. 展开更多
关键词 bastnaesite COLLECTOR Hydroxamic acids N-hydroxy-9-octadecenamide Oleic acid Rare earths
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Thermal decomposition mechanism and kinetics of bastnaesite in suspension roasting process:A comparative study in N_(2) and air atmospheres
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作者 Wenbo Li Jijia Chen +2 位作者 Shaokai Cheng Junyan Sun Xiaolong Zhang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第9期1809-1816,I0006,共9页
To investigate the thermal decomposition behavior and reaction kinetics of bastnaesite in suspension roasting,the gas and solid products of bastnaesite roasted in N2 and air atmospheres were examined using a gas analy... To investigate the thermal decomposition behavior and reaction kinetics of bastnaesite in suspension roasting,the gas and solid products of bastnaesite roasted in N2 and air atmospheres were examined using a gas analyzer,X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).Subsequently,the kinetic parameters of bastnaesite in the suspension roasting process were derived and calculated using the isothermal method.The results show that the decomposition product of bastnaesite in N_(2) is CeOF.However,once the roasting temperature exceeds 600℃,CO is generated in addition to CO_(2),and all the XRD diffraction peaks of CeOF are shifted to the right,indicating that CO_(2) can oxidize CeOF and lead to the transformation of Ce(Ⅲ) into Ce(Ⅳ).When roasted in air,the decomposition product CeOF can be completely converted to CeF3 and Ce_(7)O_(12) as it easily oxidizes.Additionally,the reaction rate of bastnaesite in air is higher than that of N_(2),and the starting reaction temperature is lower than that of N_(2).A large number of irregular cracks and holes appear on the surface of solid-phase products following suspension roasting,which are due to the thermal decomposition of bastnaesite that produces CO_(2) as well as the reconstruction of the lattice of the solid-phase products.The reaction kinetic model of bastnaesite roasted in N_(2)(temperature range 600-750℃) and air(temperatu re range 500-575℃) confo rms to the A_(3/2) model with the mechanism function G(α)=-ln(1-α)^(2/3),and the reaction activation energy is 59.78 kj/mol and lnA is 1.65 s^(-1) in N_(2) atmosphere.In air,the reaction activation energy is 100.30 kj/mol and lnA is 9.63 s^(-1). 展开更多
关键词 Rare earths bastnaesite Suspension roasting Thermal decomposition mechanism Reaction kinetics
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Separation of La(Ⅲ),Ce(Ⅳ)and Ca(Ⅱ)from bastnaesite using acidic phosphonic chitosan and rotating disk membrane
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作者 Dandan Lu Wenhui Li +1 位作者 Linlin Fan Yunren Qiu 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第5期995-1000,I0007,共7页
The separation of rare earths is difficult due to their similar properties and the complex characteristics of associated vein o res.Complexation-ultrafiltration(CUF)and shear induced o rderly dissociation coupling wit... The separation of rare earths is difficult due to their similar properties and the complex characteristics of associated vein o res.Complexation-ultrafiltration(CUF)and shear induced o rderly dissociation coupling with ultrafiltration(SIODUF)were used to separate metal ions(M,M=La(Ⅲ),Ce(Ⅳ)and Ca(Ⅱ))from simulated bastnaesite leaching solution using acidic phosphonic chitosan(aPCS)and rotating disk membrane.Effect of simultaneous removal of metallic ions was investigated by CUF,and suitable conditions were obtained for C/M 10.0(mass ratio of complexant to metal ions)and pH 5.0.The shear stabilities of aPCS-M complexes were explored at different pH values and the results show that the complexes can dissociate at a certain rotational speed,the critical one.The critical s hear rates of aPCS-La,aPCS-Ce and aPCS-Ca complexes at pH 5.0 were calculated as 1.42×10^(5).1.69×10^(5) and 9.75×10^(4) s^(-1),respectively.The order of complexes shear stability is aPCS-Ca aPCS-La<aPCS-Ce.The high selective separation of M and regeneration of aPCS were achieved by SIODUF in the light of the difference of aPCSM complexes shear stabilities.The separation coefficientsβLa/Ce andβCa/La reach 31.2 and 53.9,respectively. 展开更多
关键词 bastnaesite Rare earths Complexation-ultrafiltration Acidic phosphonic chitosan Rotating disk membrane
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Thermal decomposition and oxidation of bastnaesite concentrate in inert and oxidative atmosphere 被引量:16
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作者 Longsheng Zhao Liangshi Wang +3 位作者 Genghong Shuai Zhiqi Long Dali Cui Xiaowei Huang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2018年第7期758-764,共7页
To clearly elucidate the oxidative roasting behaviors of the bastnaesite, the thermal decomposition and oxidation of the bastnaesite concentrate in inert and oxidative atmosphere have been investigated in detail. Expe... To clearly elucidate the oxidative roasting behaviors of the bastnaesite, the thermal decomposition and oxidation of the bastnaesite concentrate in inert and oxidative atmosphere have been investigated in detail. Experimental data indicated that the initial decomposition temperature of the concentrate under N2 atmosphere is 150 ℃ higher than that under O2 atmosphere,most likely because the oxidation of the cerium induces the decomposition of the concentrate. For the roasted samples under N2 atmosphere at500 ℃ and above,the oxidation efficiency of the cerium is 19.8%-26.8% because of the fact that rareearth fluorocarbonate is first decomposed to form rare-earth oxyfluoride and CO2, and the cerium oxyfluoride is then partially oxidized by the CO2 gas. The rest cerium in these samples can be further oxidized in air at room temperature, with the oxidation efficiency of the cerium gradually increasing to above 80% in 7 d. This can be attributed to the obvious changes in the inner morphology of the roasted samples under N2 atmosphere at high temperatures, which largely induce the diffusion of the air and improves the oxidation activity of CeOF, and further induces the oxidation of CeOF by the air. XRD and XPS techniques were used to further verify the significant differences in the thermal decomposition behaviors of the bastnaesite concentrate under N2 and O2 atmosphere. Moreover, no oxidation of Pr^(3+) to Pr^(4+) in the roasted samples under both N2 and O2 atmosphere is observed. This gives an overall understanding of the oxidative roasting of the bastnaesite concentrate without additives. 展开更多
关键词 bastnaesite Thermal decomposition Oxidation Inert atmosphere Oxidative atmosphere Rare earths
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Interaction of reactive oily bubble in flotation of bastnaesite 被引量:10
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作者 周芳 王娄翔 +2 位作者 徐政和 刘青侠 池汝安 《Journal of Rare Earths》 SCIE EI CAS CSCD 2014年第8期772-778,共7页
To understand the flotation mechanism of bastnaesite using reactive oily bubble, the interaction between bastnaesite parti-cles and reactive oily bubbles was investigated by electro-kinetic studies, induction time mea... To understand the flotation mechanism of bastnaesite using reactive oily bubble, the interaction between bastnaesite parti-cles and reactive oily bubbles was investigated by electro-kinetic studies, induction time measurements and small-scale flotation ex-periments. The bastnaesite flotation could be seen as a hetero-coagulation between bastnaesite particles and reactive oily bubbles which was confirmed by the zeta potential distribution and induction time measurements from pH 4.8 to pH 9.0. The small-scale flotation tests were consistent with the hetero-coagulation results, and showed a better flotation of reactive oily bubble than air bubble among all pH range. The interaction force between bastnaesite particles and reactive oily bubbles was evaluated by the classical DLVO theory. It indicated that the attachment could be predicted well by the DLVO theory only in a restricted pH range due to the absence of hydrophilic interaction repulsion force and chemical interaction force. 展开更多
关键词 bastnaesite reactive oily bubble FLOTATION hetero-coagulation DLVO theory rare earths
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Study on leaching rare earths from bastnaesite treated by calcification transition 被引量:9
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作者 黄宇坤 张廷安 +2 位作者 豆志河 刘江 唐方方 《Journal of Rare Earths》 SCIE EI CAS CSCD 2014年第11期1043-1047,共5页
Extracting rare earths from bastnaesite concentrate treated by calcification transition was studied through the single factor test and XRD patterns of bastnaesite after calcification and slags after leaching in HCl so... Extracting rare earths from bastnaesite concentrate treated by calcification transition was studied through the single factor test and XRD patterns of bastnaesite after calcification and slags after leaching in HCl solution. And the effects of the main calcified parameters such as temperature, liquid/solid and calcified time on transition performance of bastnaesite were investigated. It was found that under the optimal conditions of calcification temperature of 250 oC, liquid/solid of 20 mL/g, calcification time of 180 min, the highest leaching rate of rare earth were obtained, with the leaching ratio of rare earths 83.70% and Ce 77.01%, La 90.55%, Nd 92.03%, respectively; loss rates of fluorine with different calcification conditions were always less than 1% and XRD patterns of calcification slags and leaching slags showed that fluorine existed in the form of CaF2. 展开更多
关键词 bastnaesite calcification transformation acid leaching leaching ratio rare earths
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Structural and electronic properties of bastnaesite and implications for surface reactions in flotation 被引量:6
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作者 Shiming Cao Yijun Cao +2 位作者 Zilong Ma Yinfei Liao Xiaolin Zhang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2020年第3期332-338,共7页
The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then ... The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then the Mulliken populations,electron density and density of states were calculated and further analyzed in detail.The calculation results reveal that it mainly ruptures along the ionic Ce-O and Ce-F bonds during the cleavage of bastnaesite,leaving≡Ce^+,≡F^-and≡CO3^-dangling bonds exposed on the cleavage surface of bastnaesite.Combined with contact angle measurement,surface complexation theory and XPS analysis,the implications of structural and electronic properties on bastnaesite flotation reactions were studied.The hydration of exposed strong ionic bond on cleavage surface results in hydrophilic surface.According to surface complexation theory,the formed surface groups are≡CeOH^0,≡CO3 H^0 and≡FH^0 groups.The investigated metal ions and flotation reagents complex with surface≡CeOH^0 groups,while≡CO3H^0 and≡FH^0 groups are not involved in the complexation.The high activity of Ce atoms facilitates these surface reactions. 展开更多
关键词 bastnaesite Density FUNCTIONAL theory calculation Electronic PROPERTY FLOTATION RARE earths
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Synergistic depression mechanism of Ca^(2+) ions and sodium silicate on bastnaesite flotation 被引量:6
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作者 Zhao Cao Zeyu Cheng +1 位作者 Jieliang Wang Yongdan Cao 《Journal of Rare Earths》 SCIE EI CAS CSCD 2022年第6期988-995,I0006,共9页
Bastnaesite is an important rare earth mineral and is usually beneficiated by flotation.Sodium silicate is commonly used to depress calcium-bearing gangue minerals,however it can also depress bastnaesite when Ca^(2+) ... Bastnaesite is an important rare earth mineral and is usually beneficiated by flotation.Sodium silicate is commonly used to depress calcium-bearing gangue minerals,however it can also depress bastnaesite when Ca^(2+) ions exist in the pulp.In this study,the effect of Ca^(2+) ions and sodium silicate individually or in combination on bastnaesite flotation was studied through micro-flotation,zeta potential,fluorescence spectroscopy and X-ray photoelectron spectroscopy(XPS) measurements.Micro-flotation results show that the combination of Ca^(2+) ions and sodium silicate depresses bastnaesite more severely due to their synergistic effect.Zeta potential results show that the combination renders the surface potential of bastnaesite negatively shifted more significantly.Fluorescence spectroscopy shows that the combination decreases the surface hydrophobicity of bastnaesite more severely.XPS shows that the combination increases the adsorption of sodium silicate on bastnaesite by forming hydrophilic Ca-SiO_(3) precipitate,which causes more serious depression on bastnaesite flotation. 展开更多
关键词 bastnaesite FLOTATION Sodium silicate Ca^(2+)ions Synergistic depression Rare earths
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Isoconversional kinetic analysis of decomposition of bastnaesite concentrates with calcium hydroxide 被引量:4
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作者 Peng Cen Xue Bian Wenyuan Wu 《Journal of Rare Earths》 SCIE EI CAS CSCD 2020年第12期1361-1371,共11页
Isoconversional methods combined with thermogravimetry were applied to investigate the decomposition kinetics of bastnaesite concentrates with different amounts of calcium hydroxide added.The apparent activation energ... Isoconversional methods combined with thermogravimetry were applied to investigate the decomposition kinetics of bastnaesite concentrates with different amounts of calcium hydroxide added.The apparent activation energy was calculated,and the results indicate that the overall reaction involves more than one single step.The reaction with a lower content(<15 wt%)of calcium hydroxide can be divided into two steps,while the reaction with a higher content(>15 wt%)involves another step which denotes the decomposition of newly formed calcium carbonate during roasting.The activation energy increases with increasing amount of calcium hydroxide in the lower range(0-15 wt%).This is due to the resistance of calcium hydroxide to heat and mass transport,However,more calcium can promote the decomposition reaction more effectively and thus reduce the activation energy.Nonlinear fitting was performed by fitting the experimental data to Avrami-Erofeev model to determine the reaction model and pre-exponential factor.The theoretical models were proven to be reliable for kinetic prediction. 展开更多
关键词 bastnaesite Thermal analysis kinetics Isoconversional method Calcium hydroxide Rare earths
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A comparative investigation into floatability of bastnaesite with three di/trialkyl phosphate surfactants 被引量:3
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作者 Hongli Fan Xianglin Yang +2 位作者 Jing Qi Guangyi Liu Jingqin Qin 《Journal of Rare Earths》 SCIE EI CAS CSCD 2021年第11期1442-1449,I0005,共9页
Flotation separation and recovery of rare earth minerals(REM) have returned to an important position due to the growing strategy demand for rare earth elements(REE).In this paper,a comparative investigation into the f... Flotation separation and recovery of rare earth minerals(REM) have returned to an important position due to the growing strategy demand for rare earth elements(REE).In this paper,a comparative investigation into the floatability of bastnaesite((Ce,La)FCO3) was conducted by using three di/trialkyl phosphate collectors,di(2-ethylhexyl) phosphate(DEHPA),dibutyl phosphate(DBP) and tributyl phosphate(TBP).The density functional theory(DFT) computation recommends that the chemical activity of the three phosphate collectors is in order of DEHPA≥ DBP >> TBP,and their hydrophobization assuggested by the IgP(oil-water partition coefficient) value is in the order of DEHPA> TBP> DBP.The micro-flotation indicates that the preferable pH values for flotation of bastnaesite with the three phosphate collectors are 7.0-8.0,and DEHPA achieves much higher flotation recovery of bastnaesite,followed by DBP,and then TBP,which coincides with their reactivity and hydrophobicity,the two prerequisites for froth flotation.The contact angle,zeta potential,Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS) deduce that DEHPA likely reacts with the Ce(Ⅲ)atoms of bastnaesite interface through its O atom(s) of the P(=O)-O-group to generate the Ce-O-P bonds,and its two 2-ethylhexyl groups orient outside for attaching bubbles,resulting in flotation enrichment of bastnaesite.Furthermore,this investigation offers a novel strategy for developing collectors in selective beneficiation of REM. 展开更多
关键词 di(2-ethylhexyl)phosphoric acid bastnaesite FLOTATION Mechanism Activity Rare earths
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Phase transition of bastnaesite concentrate in calcification process 被引量:3
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作者 Yu-Kun Huang Ting-An Zhang +2 位作者 Zhi-He Dou Jiang Liu Fang-Fang Tang 《Rare Metals》 SCIE EI CAS CSCD 2016年第8期649-654,共6页
The phase transformation in calcification process was investigated by X-ray diffraction (XRD) and differential scanning calorimeter (DSC), and the effect of calcification on the leaching rate of rare earth was ana... The phase transformation in calcification process was investigated by X-ray diffraction (XRD) and differential scanning calorimeter (DSC), and the effect of calcification on the leaching rate of rare earth was analyzed. The results show that bastnaesite transforms into rare earth hydrate at the cal- cification temperature range of 225-300 ℃. However, this transition is verified to be an efficient reaction for the acti- vating bastnaesite when the temperature is higher than 200 ℃. The leaching rate of rare earth increases to 89.17 % for activating bastnaesite from 36.27 % for the bastnaesite, and it is the highest with calcification temperature of 250 ℃, which is consistent with the result of DSC analysis. The transition of rare earth oxyfluoride into RE(OH)3 is acceler- ated by the addition of NaOH according to the experiments of different calcification systems. 展开更多
关键词 bastnaesite Calcification transformation Solidfluoride reaction Mineral phase transition
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Decomposition process of bastnaesite concentrate in NaOH-CaO-H2O system 被引量:2
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作者 Jiang Liu Ting’an Zhang +2 位作者 Zhihe Dou Yan Liu Guozhi Lv 《Journal of Rare Earths》 SCIE EI CAS CSCD 2019年第7期760-766,共7页
A novel process of calcification-leaching for bastnaesite concentrate(REFCO3) was proposed. The prior calcification was carried out in the system of NaOH-CaO-H2O and the lgC-pH pattern for Ce-F-Ca-C-H2O system was dra... A novel process of calcification-leaching for bastnaesite concentrate(REFCO3) was proposed. The prior calcification was carried out in the system of NaOH-CaO-H2O and the lgC-pH pattern for Ce-F-Ca-C-H2O system was drawn. The thermodynamics result indicates that decomposition for bastnaesite requires certain alkaline condition, but excessive alkalinity also causes decomposition of CaF2. XRD and SEM-EDS analyses on the calcification-leaching process reveal that bastnaesite first decomposes into RE(OH)3 and CaF2. Then, by HCl leaching rare earths were extracted,while CaF2 was left in the leaching residue. In addition, effects of temperature, time, NaOH and CaO on the calcification were investigated. The results show that the leaching rate of rare earths(REs)reaches 72.5 wt%, at the same time 99.2 wt% of F is left in leaching residue with 20 wt% NaOH and 38 wt% CaO at 493 K for 180 min. 展开更多
关键词 bastnaesite CONCENTRATE CALCIFICATION PROCESS Thermodynamics FLUORINE Rare earths
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Kinetic study on bastnaesite concentrate mechanochemical decomposition in NaOH solution 被引量:2
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作者 Jiang Liu Zhihe Dou Ting’an Zhang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2020年第4期418-426,共9页
Mechanochemical reaction involves simultaneous chemical reaction and particle crushing;the latter increases the effective reaction area and improves the reactivity,thus enhancing its kinetics.The classical shrinking c... Mechanochemical reaction involves simultaneous chemical reaction and particle crushing;the latter increases the effective reaction area and improves the reactivity,thus enhancing its kinetics.The classical shrinking core model was used to model the kinetics of bastnaesite mechanochemical decomposition in NaOH solution,which shows a questionable result.Mechanochemical reaction is a dynamic process,where the particle shape and concentration in reaction interface undergo constant change.Thus,a physically consistent model was applied to describe the kinetics.The variations in OH^-concentration and particle shape were considered in the revision of model.Considering the variation in OH^-concentration in solution with time,the model with varying OH^-concentration agrees better with the experimental data,improving the regression coefficients to between 0.936 and 0.992.By introducing fractal geometry to deal with the irregular system,the model was further optimized,and the regression coefficients increase to between 0.940 and 0.997.All these models considere shrinking particle approaches and controlling mechanisms for the diffusion and chemical reaction.Finally,the fractal model with varying OH^-concentration was selected to describe the mechanochemical decomposition of bastnaesite,which indicates that the process is controlled by chemical reaction. 展开更多
关键词 bastnaesite CONCENTRATE MECHANOCHEMICAL decomposition Sodium HYDROXIDE Kinetics RARE earths
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