In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distanc...In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.展开更多
Since 2011,certain advances have been made through the resource investigation,metallogenesis research,mining supervision and environmental protection of ion-adsorption type rare earth element (REE) deposit in South Ch...Since 2011,certain advances have been made through the resource investigation,metallogenesis research,mining supervision and environmental protection of ion-adsorption type rare earth element (REE) deposit in South China.Firstly,some progress has been made in REE prospecting in Jiangxi,Guangdong,Guangxi and Yunnan.REE deposits are not only found within the weathering crusts of granites and felsic volcanic rocks,but also within the weathering crusts of epimetamorphic rocks and basic magmatic rocks.Secondly,the methods of exploration,delineating ore bodies and calculation of reserves have been improved,which intuitively reflect the thickness,REE composition and value of weathering crust.Thirdly,the relationship between REEs and weathering degree and the rule of distribution,migration and enrichment of REEs in the weathering profile was summarized through the analysis of big data,which can predict the metallogenetic horizon of REEs.Fourthly,a method for quick,accurate and dynamic investigation of the REE deposit has been established by using high resolution remote sensing technology.Finally,the relation between the production status of REE mines and water pollution has been revealed based on long-term hydrochemical monitoring data of rivers and wells in mines and surrounding areas.展开更多
The magnesium sulfate(MgSO_(4))-ascorbic acid(Vc)compound leaching technique can extract rare earth elements(REEs)existing in ion-exchangeable phase and colloidal phase from ion-adso rption type rare earth ore through...The magnesium sulfate(MgSO_(4))-ascorbic acid(Vc)compound leaching technique can extract rare earth elements(REEs)existing in ion-exchangeable phase and colloidal phase from ion-adso rption type rare earth ore through the synergy effect of coordination and reduction,but its reaction process and mechanism remain unclear.In this paper,the coordination-reduction leaching mechanism was analyzed from the perspectives of leaching thermodynamics and kinetics,which provide theoretical guidance for the compound leaching process.In the case of neodymium,about 45%of dissolved neodymium will exist as the complex species of NdVc_(()3(aq))in Nd-Vc-sulfate system.Based on this,it is deduced that the Gibbs free energy of the leaching reaction of ion-exchangeable phase REEs will change to a more negative value through the coordination of REEs cations and Vc anions in the MgSO_(4)leaching process.In addition,the E_(h)-pH diagrams of Ce-SO_(4)^(2-)-H_(2)O and Fe-SO_(4)^(2-)-H_(2)O together with the dissolution experiments confirm that the added Vc initiates the leaching process of colloidal phase REEs through reduction-dissolution reaction.Through the study of leaching kinetics,the leaching of REEs is controlled by diffusion and chemical reaction in the co mpound leaching system since colloidal phase REEs are leached.Therefore,the addition of Vc can shift the leaching equilibrium to a more favorable state and accelerate leaching process.The rare earth leaching efficiency of ion-exchangeable phase and colloidal phase can be effectively improved by increasing the reaction temperature,the conce ntrations of leaching agent and Vc,and the leaching agent acidity.展开更多
To investigate the process of RE^(3+)anti-adsorption on ion-adsorption type rare earth tailings,the thermodynamics,adsorption kinetics and infrared spectroscopy of these materials were investigated.The results indicat...To investigate the process of RE^(3+)anti-adsorption on ion-adsorption type rare earth tailings,the thermodynamics,adsorption kinetics and infrared spectroscopy of these materials were investigated.The results indicate that the initial reaction rate of anti-adsorption of rare earth tailings is fast,but it reaches a balance in 6 min.The formula 1-2a/3-(1-a)2/3=k_2t(k represents rate constant of the reaction,a represents anti-adsorption rate of rare earth ore,t represents anti-adsorption time)of internal diffusion can be used to predict the kinetics of anti-adsorption in IATRE tailings.BecauseΔH<0,ΔG<0,ΔS>0(ΔH,ΔG,ΔS represent change of enthalpy,Gibbs free energy and entropy,respectively),the anti-adsorption of RE^(3+)on ion-adsorption type RE tailings is a spontaneous physical adsorption process.The effects of ligand exchange and strong chemical bond are not found in this process.Because the anti-adsorption process is exothermic,heating will inhibit the reaction and decrease the anti-adsorption performance.According to the infrared spectrum analysis,there are no significant changes in the mineral surface after anti-adsorption.Based on these findings,the anti-adsorption of rare earth tailings is physical adsorption.展开更多
The practice ofin-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate could only leach most of rare earth in ion-exchangeable phase, but not the colloidal sediment phase. Therefore, the redu...The practice ofin-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate could only leach most of rare earth in ion-exchangeable phase, but not the colloidal sediment phase. Therefore, the reduction leaching of rare earth from the ion-adsorption type rare earths ore with ferrous sulfate was innovatively put forward. The soak leaching process and the column leaching process were investigated in the present study. It was determined that ion-exchangeable phase could be released, and part of colloidal sediment phase rare earth could be reduction leached by the cations with reduction properties. The mechanism of reduction leaching was discussed with the Eh-pH diagram of cerium. Moreover, the stronger reduction of reductive ions, the greater acidity of leaching agent solution, and the higher reductive ion concentration, could result in the higher rare earth efficiency and the bigger ce-rium partition in the leaching liquor. In the ferrous sulfate column leaching process, the rare earth leaching rate and the rare earth effi-ciency were a little higher than with (NH4)2SO4 agent, and the rare earth efficiency and the partitioning of cerium in leaching liquor could be about 102% and 5.31%, respectively. However, the ferrous sulfate leaching process revealed some problems, so compound leaching with magnesium sulfate and a small amount of ferrous sulfate was proposed to an excellent alternative leaching agent for further studies, which may realize efficiency extraction and be environment-friendly.展开更多
The fractionation of ion adsorption rare earths(IAREs) along the depth in a shaft of a deposit at Dajishan,Jiangxi, China was comparatively evaluated using the partition values(PVs) and relative fractionation values(R...The fractionation of ion adsorption rare earths(IAREs) along the depth in a shaft of a deposit at Dajishan,Jiangxi, China was comparatively evaluated using the partition values(PVs) and relative fractionation values(RFVs) of the leached rare earths(REs). It is found that both PVs and RFVs can objectively reflect the migration and fractionation of REs, but RE content and abrasion pH could not. However, the RFVs can provide more information to quantitatively evaluating the migration and fractionation characteristics of REs along the selected direction and region than PVs could, which is of significance for designing the optimal procedures of in-situ leaching based on the determined flow direction of injecting solution. It is demonstrated that the migration of Ce, Pr, and Nd along the depth direction is inert, and that of REs post Sm and Y is active. Meanwhile, the migration of La shows region characteristics which is active in the upper and inert in lower region. More interesting, the dependence of RFVs on atomic number of REs displays a tetrad group variation trend. However, the fractionation of REs among clay minerals with different particle sizes is not evident, especially for the clay in the bottom region. These results indicate that the migration and fractionation of REs not only are dominated by the adsorption of their hydrated ions, but also rely on their hydrolysis tendency, which provide information for understanding the metallogenic mechanism of IAREs.展开更多
The establishment of a mathematical model for the ion exchange process is key to creating a theoretical basis for the mining of ion-adsorption type rare earth ores.Ore samples from Xinfeng,Xunwu and Anyuan were used a...The establishment of a mathematical model for the ion exchange process is key to creating a theoretical basis for the mining of ion-adsorption type rare earth ores.Ore samples from Xinfeng,Xunwu and Anyuan were used as the test ore samples in the present study and equilibrium batch tests of ore sample leaching using various ammonium sulfate concentrations were performed.The results show that,after leaching,there is a negative exponential relationship between the ratio of the solid-phase rare earth ion concentration to the aqueous-phase rare earth ion concentration and the initial ammonium ion concentration.However,there is a linear relationship between the natural logarithm of the ratio of the solidphase ammonium ion concentration to the aqueous-phase ammonium ion concentration and the initial ammonium ion concentration.Based on the above two functional relationships,a two-parameter model for the equilibrium ion exchange process of ion-adsorption type rare earth ores was established.Using the established model to analyze the test data the model error for the Xunwu ore sample is found to be less than 5%.The proposed model is more accurate compared with the Kerr model.The two-parameter model proposed in this study provides theoretical support for the numerical simulation of column leaching(in-situ leaching)of ion-adsorption type rare earth ores.展开更多
To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the abs...To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence and presence of carboxylic acids. The results show that all the tested organic acids(acetic acid,malonic acid, citric acid, tartaric acid, succinic acid, and malic acid) can promote RE extraction. At relatively high concentrations of organic acids, the activation efficiency of organic acids on RE extraction is generally consistent with their complexation ability; whereas at their low concentrations, the change of zeta potential on the IRE-ore surface with organic acid concentration and p H has a close association with RE extraction, which indicates that organic acids can impact the surface electrical property of IREore via their adsorption/desorption, and thereby increase/decrease the affinity of RE ions to IRE-ore.Therefore the influence of organic acids on the IRE-ore surface electrical property also plays an important role in RE extraction in addition to their complexation with RE ions.展开更多
Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid vol...Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid volcanic and subvolcanic rocks. The distribution of REE contents in weathered profiles shows an are-shaped pattern. It indicates that the REE contents are enriched in full weathered and upper parts of sub-weathered zones. The REE patterns-in weathered crusts also demonstrate characteristics essentially inherited from those in unaltered rocks; On the other hand, cerium; has a positive anomaly in soil zone and negative anomalies in full weathered and sub-weathered zones. Gradual decrease in the slopes of the REE pattern curves indicates that HREE contents are more enriched than LREE in lower portion of the pro files. REE abundance in unaltered rocks and appropriate climate are essential conditions for ion adsorpted deposits. According to experiments of the REE adsorption on clay minerals, REE concentrations, pH values and ion strength in solutions significantly affect adsorption contents and partition coefficients. The distribution of the REE in weathered profiles are controlled by percolation and adsorption coupling in groundwater-rock interaction systems.展开更多
In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, whic...In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, which contain only 21.47~29.71 wt% of total REE in granites,is calculated.The petrogenetic relationship be- tween three different stages of the granites in the complex is discussed,and a geochemical model is suggested for the formation of granitic magma in early stage by partial melting of the crustal basement rocks containing more REE than that in the late stage.It shows that a ion-adsorption type of REE deposit could ocuur in the weath- ering crust on the early stage granite.Rb-Sr isotope isochron dating of the first stage medium-coarse-grained K-feldspar granite shows that its age is 146.5 Ma and initial ^(87)Sr/^(86)Sr ratio is 0.71198.展开更多
In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried o...In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6%and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO3 and Al2O3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900℃and the thermal decomposition of RE2O2SO4 at 900-1300℃.Therefore,a high-temperature calcinations method for removing SO3 from precipitates is proposed.When the precipitates are calcined at 1300℃for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.展开更多
In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore,the extra...In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore,the extraction mechanism and separation behaviors of Nd^(3+)and Al^(3+)in the Nd_(2)(SO_(4))_(3)-AI_(2)(SO_(4))_(3) mixed solution using P507 were studied in this work.The extraction of Nd^(3+)and Al^(3+)follows the cation exchange mechanism.With the increase of the equilibrium pH,β_(Nd/Al) in the extraction of the Nd_(2)(SO_(4))_(3)-Al_(2)(SO_(4))_(3) mixed solution using P507 is always higher than that in the extraction of single Nd_(2)(SO_(4))_(3) and Al_(2)(SO_(4))_(3) solutions.It can be attributed to the fact that the extraction of Nd^(3+)using P507 is much faster than that of Al^(3+),and Al^(3+)is more prone to be hydrolyzed at lower pH.β_(Nd/Al) in the extraction of the Nd_(2)(SO_(4))_(3)-Al_(2)(SO_(4))_(3) mixed solution decreases gradually with the increase of mixing time within the equilibrium pH range of 1.5-1.9.The extraction of Nd^(3+)using P507 is much faster than that of Al^(3+),but the stability of Al^(3+)-Ioaded organic phase is better than that of Nd^(3+)-loaded organic phase,thus Nd^(3+)in the Nd^(3+)-loaded organic phase is gradually replaced by Al^(3+)in the aqueous phase with the increase of mixing time.展开更多
Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare eart...Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate.The effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was investigated.The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and NA.The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant.The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.展开更多
基金This research was funded by the National Natural Science Foundation of China(Grant No.52174113)the Young Jinggang Scholars Award Program in Jiangxi Province,China(Grant No.QNJG2018051)the“Thousand Talents”of Jiangxi Province,China(Grant No.jxsq2019201043).
文摘In the process of ion-adsorption rare earth ore leaching,the migration characteristics of the wetting front in multi-hole injection holes and the influence of wetting front intersection effect on the migration distance of wetting fronts are still unclear.Besides,wetting front migration distance and leaching time are usually required to optimize the leaching process.In this study,wetting front migration tests of ionadsorption rare earth ores during the multi-hole fluid injection(the spacing between injection holes was 10 cm,12 cm and 14 cm)and single-hole fluid injection were completed under the constant water head height.At the pre-intersection stage,the wetting front migration laws of ion-adsorption rare earth ores during the multi-hole fluid injection and single-hole fluid injection were identical.At the postintersection stage,the intersection accelerated the wetting front migration.By using the Darcy’s law,the intersection effect of wetting fronts during the multi-hole liquid injection was transformed into the water head height directly above the intersection.Finally,based on the Green-Ampt model,a wetting front migration model of ion-adsorption rare earth ores during the multi-hole unsaturated liquid injection was established.Error analysis results showed that the proposed model can accurately simulate the infiltration process under experimental conditions.The research results enrich the infiltration law and theory of ion-adsorption rare earth ores during the multi-hole liquid injection,and this study provides a scientific basis for optimizing the liquid injection well pattern parameters of ion-adsorption rare earth in situ leaching in the future.
文摘Since 2011,certain advances have been made through the resource investigation,metallogenesis research,mining supervision and environmental protection of ion-adsorption type rare earth element (REE) deposit in South China.Firstly,some progress has been made in REE prospecting in Jiangxi,Guangdong,Guangxi and Yunnan.REE deposits are not only found within the weathering crusts of granites and felsic volcanic rocks,but also within the weathering crusts of epimetamorphic rocks and basic magmatic rocks.Secondly,the methods of exploration,delineating ore bodies and calculation of reserves have been improved,which intuitively reflect the thickness,REE composition and value of weathering crust.Thirdly,the relationship between REEs and weathering degree and the rule of distribution,migration and enrichment of REEs in the weathering profile was summarized through the analysis of big data,which can predict the metallogenetic horizon of REEs.Fourthly,a method for quick,accurate and dynamic investigation of the REE deposit has been established by using high resolution remote sensing technology.Finally,the relation between the production status of REE mines and water pollution has been revealed based on long-term hydrochemical monitoring data of rivers and wells in mines and surrounding areas.
基金supported by the National Key Research and Development Project of China(2021YFC2902202,2020YFC1909002)the National Natural Science Foundation of China(51604128)+1 种基金the Youth Jinggang Scholars Program in Jiangxi Province(QNJG2019056)the Cultivation Project of the State Key Laboratory of Green Development and High-value Utilization of Ionic Rare Earth Resources in Jiangxi Province(20194AFD44003)。
文摘The magnesium sulfate(MgSO_(4))-ascorbic acid(Vc)compound leaching technique can extract rare earth elements(REEs)existing in ion-exchangeable phase and colloidal phase from ion-adso rption type rare earth ore through the synergy effect of coordination and reduction,but its reaction process and mechanism remain unclear.In this paper,the coordination-reduction leaching mechanism was analyzed from the perspectives of leaching thermodynamics and kinetics,which provide theoretical guidance for the compound leaching process.In the case of neodymium,about 45%of dissolved neodymium will exist as the complex species of NdVc_(()3(aq))in Nd-Vc-sulfate system.Based on this,it is deduced that the Gibbs free energy of the leaching reaction of ion-exchangeable phase REEs will change to a more negative value through the coordination of REEs cations and Vc anions in the MgSO_(4)leaching process.In addition,the E_(h)-pH diagrams of Ce-SO_(4)^(2-)-H_(2)O and Fe-SO_(4)^(2-)-H_(2)O together with the dissolution experiments confirm that the added Vc initiates the leaching process of colloidal phase REEs through reduction-dissolution reaction.Through the study of leaching kinetics,the leaching of REEs is controlled by diffusion and chemical reaction in the co mpound leaching system since colloidal phase REEs are leached.Therefore,the addition of Vc can shift the leaching equilibrium to a more favorable state and accelerate leaching process.The rare earth leaching efficiency of ion-exchangeable phase and colloidal phase can be effectively improved by increasing the reaction temperature,the conce ntrations of leaching agent and Vc,and the leaching agent acidity.
基金financially supported by the National Natural Science Foundation of China(No.41662004)。
文摘To investigate the process of RE^(3+)anti-adsorption on ion-adsorption type rare earth tailings,the thermodynamics,adsorption kinetics and infrared spectroscopy of these materials were investigated.The results indicate that the initial reaction rate of anti-adsorption of rare earth tailings is fast,but it reaches a balance in 6 min.The formula 1-2a/3-(1-a)2/3=k_2t(k represents rate constant of the reaction,a represents anti-adsorption rate of rare earth ore,t represents anti-adsorption time)of internal diffusion can be used to predict the kinetics of anti-adsorption in IATRE tailings.BecauseΔH<0,ΔG<0,ΔS>0(ΔH,ΔG,ΔS represent change of enthalpy,Gibbs free energy and entropy,respectively),the anti-adsorption of RE^(3+)on ion-adsorption type RE tailings is a spontaneous physical adsorption process.The effects of ligand exchange and strong chemical bond are not found in this process.Because the anti-adsorption process is exothermic,heating will inhibit the reaction and decrease the anti-adsorption performance.According to the infrared spectrum analysis,there are no significant changes in the mineral surface after anti-adsorption.Based on these findings,the anti-adsorption of rare earth tailings is physical adsorption.
基金Project supported by National Science and Technology Support Program of China(2015BAB16B01)Training Program of Major Academic and Technical Leaders in Jiangxi Province(20142BCB22005)Top Youth Talent Training Program of "Gan Po 555 Talents Project" of Jiangxi Province
文摘The practice ofin-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate could only leach most of rare earth in ion-exchangeable phase, but not the colloidal sediment phase. Therefore, the reduction leaching of rare earth from the ion-adsorption type rare earths ore with ferrous sulfate was innovatively put forward. The soak leaching process and the column leaching process were investigated in the present study. It was determined that ion-exchangeable phase could be released, and part of colloidal sediment phase rare earth could be reduction leached by the cations with reduction properties. The mechanism of reduction leaching was discussed with the Eh-pH diagram of cerium. Moreover, the stronger reduction of reductive ions, the greater acidity of leaching agent solution, and the higher reductive ion concentration, could result in the higher rare earth efficiency and the bigger ce-rium partition in the leaching liquor. In the ferrous sulfate column leaching process, the rare earth leaching rate and the rare earth effi-ciency were a little higher than with (NH4)2SO4 agent, and the rare earth efficiency and the partitioning of cerium in leaching liquor could be about 102% and 5.31%, respectively. However, the ferrous sulfate leaching process revealed some problems, so compound leaching with magnesium sulfate and a small amount of ferrous sulfate was proposed to an excellent alternative leaching agent for further studies, which may realize efficiency extraction and be environment-friendly.
基金Project supported by National Natural Science Foundation of China(21161014,51274123)National Program on Key Basic Research Project of China(973 Program,2012VBA01204)
文摘The fractionation of ion adsorption rare earths(IAREs) along the depth in a shaft of a deposit at Dajishan,Jiangxi, China was comparatively evaluated using the partition values(PVs) and relative fractionation values(RFVs) of the leached rare earths(REs). It is found that both PVs and RFVs can objectively reflect the migration and fractionation of REs, but RE content and abrasion pH could not. However, the RFVs can provide more information to quantitatively evaluating the migration and fractionation characteristics of REs along the selected direction and region than PVs could, which is of significance for designing the optimal procedures of in-situ leaching based on the determined flow direction of injecting solution. It is demonstrated that the migration of Ce, Pr, and Nd along the depth direction is inert, and that of REs post Sm and Y is active. Meanwhile, the migration of La shows region characteristics which is active in the upper and inert in lower region. More interesting, the dependence of RFVs on atomic number of REs displays a tetrad group variation trend. However, the fractionation of REs among clay minerals with different particle sizes is not evident, especially for the clay in the bottom region. These results indicate that the migration and fractionation of REs not only are dominated by the adsorption of their hydrated ions, but also rely on their hydrolysis tendency, which provide information for understanding the metallogenic mechanism of IAREs.
基金Projects supported by the National Natural Science Foundation of China(51664015,51874147)Jiangxi University of Science and Technology Qingjiang Youth Elite Support Program(JXUSTQJBJ2016007)。
文摘The establishment of a mathematical model for the ion exchange process is key to creating a theoretical basis for the mining of ion-adsorption type rare earth ores.Ore samples from Xinfeng,Xunwu and Anyuan were used as the test ore samples in the present study and equilibrium batch tests of ore sample leaching using various ammonium sulfate concentrations were performed.The results show that,after leaching,there is a negative exponential relationship between the ratio of the solid-phase rare earth ion concentration to the aqueous-phase rare earth ion concentration and the initial ammonium ion concentration.However,there is a linear relationship between the natural logarithm of the ratio of the solidphase ammonium ion concentration to the aqueous-phase ammonium ion concentration and the initial ammonium ion concentration.Based on the above two functional relationships,a two-parameter model for the equilibrium ion exchange process of ion-adsorption type rare earth ores was established.Using the established model to analyze the test data the model error for the Xunwu ore sample is found to be less than 5%.The proposed model is more accurate compared with the Kerr model.The two-parameter model proposed in this study provides theoretical support for the numerical simulation of column leaching(in-situ leaching)of ion-adsorption type rare earth ores.
基金Project supported by National Natural Science Foundation of China(51604128)
文摘To examine the activation of organic acids on the leaching process of ion-adsorption type rare earth ore(IRE-ore), the leaching behavior of rare earth(RE) and zeta potential of IRE-ore were investigated in the absence and presence of carboxylic acids. The results show that all the tested organic acids(acetic acid,malonic acid, citric acid, tartaric acid, succinic acid, and malic acid) can promote RE extraction. At relatively high concentrations of organic acids, the activation efficiency of organic acids on RE extraction is generally consistent with their complexation ability; whereas at their low concentrations, the change of zeta potential on the IRE-ore surface with organic acid concentration and p H has a close association with RE extraction, which indicates that organic acids can impact the surface electrical property of IREore via their adsorption/desorption, and thereby increase/decrease the affinity of RE ions to IRE-ore.Therefore the influence of organic acids on the IRE-ore surface electrical property also plays an important role in RE extraction in addition to their complexation with RE ions.
文摘Based on characteristics of unaltered rocks and REE patterns, ion-adsorpted RE deposits can be devided into four types including Y-rich and Eu-poor granites, Y-mid and and Eu low granites, Eu-rich granites, Eu-mid volcanic and subvolcanic rocks. The distribution of REE contents in weathered profiles shows an are-shaped pattern. It indicates that the REE contents are enriched in full weathered and upper parts of sub-weathered zones. The REE patterns-in weathered crusts also demonstrate characteristics essentially inherited from those in unaltered rocks; On the other hand, cerium; has a positive anomaly in soil zone and negative anomalies in full weathered and sub-weathered zones. Gradual decrease in the slopes of the REE pattern curves indicates that HREE contents are more enriched than LREE in lower portion of the pro files. REE abundance in unaltered rocks and appropriate climate are essential conditions for ion adsorpted deposits. According to experiments of the REE adsorption on clay minerals, REE concentrations, pH values and ion strength in solutions significantly affect adsorption contents and partition coefficients. The distribution of the REE in weathered profiles are controlled by percolation and adsorption coupling in groundwater-rock interaction systems.
基金The research is supported by the National Natural Science Foundation of China
文摘In this paper the geochemical characteristics of rare earth elements in Guposhan granite complex in Nanling Area,South China,is systematically studied,and the balance of REE distribution in rock-forming minerals, which contain only 21.47~29.71 wt% of total REE in granites,is calculated.The petrogenetic relationship be- tween three different stages of the granites in the complex is discussed,and a geochemical model is suggested for the formation of granitic magma in early stage by partial melting of the crustal basement rocks containing more REE than that in the late stage.It shows that a ion-adsorption type of REE deposit could ocuur in the weath- ering crust on the early stage granite.Rb-Sr isotope isochron dating of the first stage medium-coarse-grained K-feldspar granite shows that its age is 146.5 Ma and initial ^(87)Sr/^(86)Sr ratio is 0.71198.
基金Project supported by Program of National Natural Science Foundation of China(51604128)China Postdoctoral Science Foundation(2017M620279,2018T110661)+3 种基金Key Projects of the Major Research and Development Program of Jiangxi Province(20171ACE50008)Qingqiang Excellent Young Talents,Jiangxi University of Science and Technology(JXUSTQJYX2018003)Key R&D Programs of Science and Technology Project of Ganzhou City([2017]179)Science and Technology Innovation Talents Program of Ganzhou City([2018] 50)
文摘In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6%and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO3 and Al2O3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900℃and the thermal decomposition of RE2O2SO4 at 900-1300℃.Therefore,a high-temperature calcinations method for removing SO3 from precipitates is proposed.When the precipitates are calcined at 1300℃for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.
基金Project supported by the Major Research Plan of the National Natural Science Foundation of China(91962211)National Key Research and Development Program of China(2018YFC1801803)+1 种基金National Natural Science Foundation of China(51804273)Major Project of Guangxi Science and Technology(Guike-AA18242022)。
文摘In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore,the extraction mechanism and separation behaviors of Nd^(3+)and Al^(3+)in the Nd_(2)(SO_(4))_(3)-AI_(2)(SO_(4))_(3) mixed solution using P507 were studied in this work.The extraction of Nd^(3+)and Al^(3+)follows the cation exchange mechanism.With the increase of the equilibrium pH,β_(Nd/Al) in the extraction of the Nd_(2)(SO_(4))_(3)-Al_(2)(SO_(4))_(3) mixed solution using P507 is always higher than that in the extraction of single Nd_(2)(SO_(4))_(3) and Al_(2)(SO_(4))_(3) solutions.It can be attributed to the fact that the extraction of Nd^(3+)using P507 is much faster than that of Al^(3+),and Al^(3+)is more prone to be hydrolyzed at lower pH.β_(Nd/Al) in the extraction of the Nd_(2)(SO_(4))_(3)-Al_(2)(SO_(4))_(3) mixed solution decreases gradually with the increase of mixing time within the equilibrium pH range of 1.5-1.9.The extraction of Nd^(3+)using P507 is much faster than that of Al^(3+),but the stability of Al^(3+)-Ioaded organic phase is better than that of Nd^(3+)-loaded organic phase,thus Nd^(3+)in the Nd^(3+)-loaded organic phase is gradually replaced by Al^(3+)in the aqueous phase with the increase of mixing time.
基金Project supported by the National Key Research and Development Project of China(2019YFC0605003)the Strategic Priority Research Program of CAS(XDA02030100)。
文摘Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate.The effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was investigated.The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and NA.The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant.The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.