Rare earth elements have been widely applied in various sectors.Bastnaesite and monazite are crucial rare earth minerals,and flotation is a vital technique for recovering fine-grained rare earth minerals and separatin...Rare earth elements have been widely applied in various sectors.Bastnaesite and monazite are crucial rare earth minerals,and flotation is a vital technique for recovering fine-grained rare earth minerals and separating them from associated gangue minerals such as fluorite and apatite.Flotation collectors play a key role in selectively adsorbing valuable minerals,enhancing their surface hydrophobicity,which has prompted considerable research interest.However,the interaction between minerals and reagents relies on the reactivity and selectivity of the reagent groups,as well as the reactive properties of the surface atoms of the minerals.This study proposes the use of H_(2)O_(2)oxidation to enhance the flotation process of rare earth minerals.The flotation experiments demonstrated that pre-adding H_(2)O_(2)before introducing the flotation collector significantly improved the grade and recovery of rare earth concentrates.The adsorption mechanisms of 2-hydroxy-3-naphthyl hydroxamic acid collector on rare earth mineral surfaces before and after H_(2)O_(2)pre-oxidation were studied.The 2-hydroxy-3-naphthyl hydroxamic acid interacts with Ce^(3+)on the surface of unoxidized rare earth minerals,forming chelate compounds with five-membered ring structures.The H_(2)O_(2)exhibited potent oxidizing properties and oxidized the Ce^(3+)on the bastnaesite and monazite surfaces to more stable Ce^(4+),which demonstrated stronger binding capability with hydroxamic acid.展开更多
The abundances of heavy elements produced in r-process nucleosynthesis in the early solar system need experimental verification.^(244)Pu could be the heaviest primordial nuclide produced before the formation of the Ea...The abundances of heavy elements produced in r-process nucleosynthesis in the early solar system need experimental verification.^(244)Pu could be the heaviest primordial nuclide produced before the formation of the Earth still being detectable today.As recent attempts failed to confirm the discovery of ^(244)Pu signals at a concentration of 1.0×10^(-18)g/g in bastnaesite reported by Hoffman et al.in this study,the total primordial ^(244)Pu in 450 g bastnaesite sample from Bayan Obo ore (China) was measured using ultrasensitive compact accelerator mass spectrometry (AMS).As no ^(244)Pu signal was detected,an upper limit for the ^(244)Pu in our bastnaesite sample was estimated to be 2.1×10^(-20)g/g at 99%confidence level.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52174236)Fundamental Research Funds for the Central Universities(No.FRF-DF-23-001)the Natural Science Foundation of Inner Mongolia of China(Nos.2024MS05061 and 2023LHMS05050)。
文摘Rare earth elements have been widely applied in various sectors.Bastnaesite and monazite are crucial rare earth minerals,and flotation is a vital technique for recovering fine-grained rare earth minerals and separating them from associated gangue minerals such as fluorite and apatite.Flotation collectors play a key role in selectively adsorbing valuable minerals,enhancing their surface hydrophobicity,which has prompted considerable research interest.However,the interaction between minerals and reagents relies on the reactivity and selectivity of the reagent groups,as well as the reactive properties of the surface atoms of the minerals.This study proposes the use of H_(2)O_(2)oxidation to enhance the flotation process of rare earth minerals.The flotation experiments demonstrated that pre-adding H_(2)O_(2)before introducing the flotation collector significantly improved the grade and recovery of rare earth concentrates.The adsorption mechanisms of 2-hydroxy-3-naphthyl hydroxamic acid collector on rare earth mineral surfaces before and after H_(2)O_(2)pre-oxidation were studied.The 2-hydroxy-3-naphthyl hydroxamic acid interacts with Ce^(3+)on the surface of unoxidized rare earth minerals,forming chelate compounds with five-membered ring structures.The H_(2)O_(2)exhibited potent oxidizing properties and oxidized the Ce^(3+)on the bastnaesite and monazite surfaces to more stable Ce^(4+),which demonstrated stronger binding capability with hydroxamic acid.
基金financially supported by the National Natural Science Foundation of China (Nos. 11675150, 12005197 and 12175201)。
文摘The abundances of heavy elements produced in r-process nucleosynthesis in the early solar system need experimental verification.^(244)Pu could be the heaviest primordial nuclide produced before the formation of the Earth still being detectable today.As recent attempts failed to confirm the discovery of ^(244)Pu signals at a concentration of 1.0×10^(-18)g/g in bastnaesite reported by Hoffman et al.in this study,the total primordial ^(244)Pu in 450 g bastnaesite sample from Bayan Obo ore (China) was measured using ultrasensitive compact accelerator mass spectrometry (AMS).As no ^(244)Pu signal was detected,an upper limit for the ^(244)Pu in our bastnaesite sample was estimated to be 2.1×10^(-20)g/g at 99%confidence level.
