This study focuses on the trace and rare earth elements(REE)geochemistry of the Nkporo and Ekenkpon Shales of the Calabar Flank.The main aim is to infer their depositional environment and the degree of their metal enr...This study focuses on the trace and rare earth elements(REE)geochemistry of the Nkporo and Ekenkpon Shales of the Calabar Flank.The main aim is to infer their depositional environment and the degree of their metal enrichment.The shale samples were analyzed using inductively coupled plasma mass spectrometry.The results indicated that the mean concentrations of K,Na,and Fe in Nkporo and Ekenkpon Shales are 1.45,0.4,and 4.17 wt%,and 1.11,0.44,and 5.42 wt%;respectively.The Nkporo Shale is enriched with the following trace elements;P>Mn>Sr>Ba>Zn>Ce>Rb>Zr>V>Cr>Ni and depleted in the following trace elements;Ta>Ge>Sb>Bi>Cd>Ag>Te>In>Hg.While the Ekenkpon Shale is enriched with the following trace elements;P>Mn>Ba>Sr>V>Ce>Zr>Rb>Cr>Zn>Ni and depleted in;Sb>Ge>Bi>Ag>Ce>Te>In>Hg.The concentration of redox-sensitive elements such as V,Ni,Mo,U,Cu,Cr,Re,Cd,Sb,Ti,Mn,and their ratio V/Mo and U/Mo in the black and grey shale samples show different patterns.The REE obtained from the Nkporo and Ekenkpon Shales were PAAS normalized.The Nkporo Shale showed a slightly flat light rare-earth element(LREE),middle rare-earth element(MREE),and heavy rare earth element(HREE)pattern enrichment.Ce/Ce*ranges from 0.95 to 1.09 in Nkporo Shale and 0.67 to 1.40 in Ekenkpon Shale.The Ekenkpon Shale showed a slight LREE,MREE enrichment,and depleted HREE patterns.The Mn contents and U/Mo ratio in Nkporo and Ekenkpon Shales suggests a poor oxygen transitional environment.The V/Mo and V/(V+Ni)ratios indicated that the Nkporo shales were deposited in an anoxic to suboxic conditions and Ekenkpon shales were also deposited under an anoxic to suboxic conditions.The V/Ni ratio indicated that the organic matter in the Nkporo shale is terrigenous while that of the Ekenkpon shales are both terrigenous and marine in origin.展开更多
Monocrystals are synthesized and grown according to Bridgman-Stockbarger method, and the influence of rare earth elements (REE) as well as of γ-irradiation on electrophysical properties of (SnSe)1-x - (SnSe)x (Ln - P...Monocrystals are synthesized and grown according to Bridgman-Stockbarger method, and the influence of rare earth elements (REE) as well as of γ-irradiation on electrophysical properties of (SnSe)1-x - (SnSe)x (Ln - Pr, Tb, Er) alloy system is investigated. During transition from SnSe to (SnSe)1-x - (SnSe)x solid solutions, a partial compensation of charge carriers occurs and additional scattering centres appear. At low temperatures T after irradiation with γ-quanta, thermoemf in samples of p-type conduction becomes higher and decreases in those of n-type conduction. In addition, under the influence of γ-rays radiation, defects come into being causing a decrease in lattice heat conduction and a rise in electron heat conduction. REE impurities are supposed to be positioned among the points of crystal lattice during irradiation with γ-quanta and, moreover, Frenkel defects are formed.展开更多
Queensland could likely play host to a number of rare minerals, as geologists have unearthed evidence suggesting the presence of platinum and gold, as well as rare-earth elements (REE). "This may be a whole new f...Queensland could likely play host to a number of rare minerals, as geologists have unearthed evidence suggesting the presence of platinum and gold, as well as rare-earth elements (REE). "This may be a whole new frontier for Queensland," Natural Resources and Mines Minister Dr Anthony Lynham said over the weekend. "Beyond the potential economic boost for Queensland, the discovery brings a new understanding of mineral potential in a previously under-explored area."展开更多
The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dom...The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dominant, followed by REE desorption. Finally adsorption and desorption tend to reach equilibration. The capability of iron hydroxide colloids to adsorb the HREE is greater than that to adsorb the LREE. With increasing pH, LREE/HREE fractionations will take place between iron hydroxide colloids and water, leading to the reduction of their partition coefficient ratio (DLREE/DHREE). The DREE distribution patterns show Y anomalies (DY/DHo <1), with obvious REE tetrad effects appearing under low pH conditions. Experimental results have shown that there do exist REE tetrad effects in nature. In addition to pH, the chemical type of surface water and ion intensity are also the important factors controlling REE tetrad effects and leading to fractionations between particulate-adsorbed REE and dissolved REE.展开更多
Separation and purification of critical metal ions such as rare-earth elements （REEs）, scandium and niobium from their minerals is difficult and often deter- mines if extraction is economically and environmentally f...Separation and purification of critical metal ions such as rare-earth elements （REEs）, scandium and niobium from their minerals is difficult and often deter- mines if extraction is economically and environmentally feasible. Solvent extraction is a commonly used metal-ion separation process, usually favored because of its sim- plicity, speed and wide scope, which is why it is often employed for separating trace metals from their minerals. However, the types of solvents widely used for the recovery of metal ions have adverse environmental impact. Alternatives to solvent extraction have been explored and advances in separation technologies have shown commer- cial establishment of liquid membranes as an alternative to conventional solvent extraction for the recovery of metals and other valuable materials. Liquid membrane transport incorporates solvent extraction and membrane separation in one continuously operating system. Both methods con- ventionally use solvents that are harmful to the environ- ment, however, the introduction of ionic liquids （ILs） over the last decade is set to minimize the environmental impact of both solvent extraction and liquid membrane separation processes. ILs are a family of organic molten salts with low or negligible vapour pressure which may be formed below 100 ~C. Such liquids are also highly thermally stable and less toxic. Their ionic structure makes them thermody- namically favorable solvents for the extraction of metallic ions. The main aim of this article is to review the current achievements in the separation of REE, scandium, niobium and vanadium from their minerals, using ILs in eithersolvent extraction or liquid membrane processes. The mechanism of separation using ILs is discussed and the engineering constraints to their application are identified.展开更多
文摘This study focuses on the trace and rare earth elements(REE)geochemistry of the Nkporo and Ekenkpon Shales of the Calabar Flank.The main aim is to infer their depositional environment and the degree of their metal enrichment.The shale samples were analyzed using inductively coupled plasma mass spectrometry.The results indicated that the mean concentrations of K,Na,and Fe in Nkporo and Ekenkpon Shales are 1.45,0.4,and 4.17 wt%,and 1.11,0.44,and 5.42 wt%;respectively.The Nkporo Shale is enriched with the following trace elements;P>Mn>Sr>Ba>Zn>Ce>Rb>Zr>V>Cr>Ni and depleted in the following trace elements;Ta>Ge>Sb>Bi>Cd>Ag>Te>In>Hg.While the Ekenkpon Shale is enriched with the following trace elements;P>Mn>Ba>Sr>V>Ce>Zr>Rb>Cr>Zn>Ni and depleted in;Sb>Ge>Bi>Ag>Ce>Te>In>Hg.The concentration of redox-sensitive elements such as V,Ni,Mo,U,Cu,Cr,Re,Cd,Sb,Ti,Mn,and their ratio V/Mo and U/Mo in the black and grey shale samples show different patterns.The REE obtained from the Nkporo and Ekenkpon Shales were PAAS normalized.The Nkporo Shale showed a slightly flat light rare-earth element(LREE),middle rare-earth element(MREE),and heavy rare earth element(HREE)pattern enrichment.Ce/Ce*ranges from 0.95 to 1.09 in Nkporo Shale and 0.67 to 1.40 in Ekenkpon Shale.The Ekenkpon Shale showed a slight LREE,MREE enrichment,and depleted HREE patterns.The Mn contents and U/Mo ratio in Nkporo and Ekenkpon Shales suggests a poor oxygen transitional environment.The V/Mo and V/(V+Ni)ratios indicated that the Nkporo shales were deposited in an anoxic to suboxic conditions and Ekenkpon shales were also deposited under an anoxic to suboxic conditions.The V/Ni ratio indicated that the organic matter in the Nkporo shale is terrigenous while that of the Ekenkpon shales are both terrigenous and marine in origin.
文摘Monocrystals are synthesized and grown according to Bridgman-Stockbarger method, and the influence of rare earth elements (REE) as well as of γ-irradiation on electrophysical properties of (SnSe)1-x - (SnSe)x (Ln - Pr, Tb, Er) alloy system is investigated. During transition from SnSe to (SnSe)1-x - (SnSe)x solid solutions, a partial compensation of charge carriers occurs and additional scattering centres appear. At low temperatures T after irradiation with γ-quanta, thermoemf in samples of p-type conduction becomes higher and decreases in those of n-type conduction. In addition, under the influence of γ-rays radiation, defects come into being causing a decrease in lattice heat conduction and a rise in electron heat conduction. REE impurities are supposed to be positioned among the points of crystal lattice during irradiation with γ-quanta and, moreover, Frenkel defects are formed.
文摘Queensland could likely play host to a number of rare minerals, as geologists have unearthed evidence suggesting the presence of platinum and gold, as well as rare-earth elements (REE). "This may be a whole new frontier for Queensland," Natural Resources and Mines Minister Dr Anthony Lynham said over the weekend. "Beyond the potential economic boost for Queensland, the discovery brings a new understanding of mineral potential in a previously under-explored area."
基金This work was supported by the State Outsanding Young Scientists Foundation (Grant No. 49625304) the Pre-selected Project under the State Climbing Program of China (Grant No. 95-39).
文摘The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dominant, followed by REE desorption. Finally adsorption and desorption tend to reach equilibration. The capability of iron hydroxide colloids to adsorb the HREE is greater than that to adsorb the LREE. With increasing pH, LREE/HREE fractionations will take place between iron hydroxide colloids and water, leading to the reduction of their partition coefficient ratio (DLREE/DHREE). The DREE distribution patterns show Y anomalies (DY/DHo <1), with obvious REE tetrad effects appearing under low pH conditions. Experimental results have shown that there do exist REE tetrad effects in nature. In addition to pH, the chemical type of surface water and ion intensity are also the important factors controlling REE tetrad effects and leading to fractionations between particulate-adsorbed REE and dissolved REE.
文摘Separation and purification of critical metal ions such as rare-earth elements （REEs）, scandium and niobium from their minerals is difficult and often deter- mines if extraction is economically and environmentally feasible. Solvent extraction is a commonly used metal-ion separation process, usually favored because of its sim- plicity, speed and wide scope, which is why it is often employed for separating trace metals from their minerals. However, the types of solvents widely used for the recovery of metal ions have adverse environmental impact. Alternatives to solvent extraction have been explored and advances in separation technologies have shown commer- cial establishment of liquid membranes as an alternative to conventional solvent extraction for the recovery of metals and other valuable materials. Liquid membrane transport incorporates solvent extraction and membrane separation in one continuously operating system. Both methods con- ventionally use solvents that are harmful to the environ- ment, however, the introduction of ionic liquids （ILs） over the last decade is set to minimize the environmental impact of both solvent extraction and liquid membrane separation processes. ILs are a family of organic molten salts with low or negligible vapour pressure which may be formed below 100 ~C. Such liquids are also highly thermally stable and less toxic. Their ionic structure makes them thermody- namically favorable solvents for the extraction of metallic ions. The main aim of this article is to review the current achievements in the separation of REE, scandium, niobium and vanadium from their minerals, using ILs in eithersolvent extraction or liquid membrane processes. The mechanism of separation using ILs is discussed and the engineering constraints to their application are identified.
