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Mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore

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Journal of rare earths 2017年第9期35卷 906-910页

作者：胡谷华冯宗玉董金诗孟祥龙肖燕飞刘向生 chalco guangxi nonferrous rare earth development co. Ltd.Nanning 530000China National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co.Ltd.Beijing 100088China

Weathered crust elution-deposited rare earth ore is an important resource of rare earths, including grantic weathered crust elution-deposited rare earth ore and volcanic weathered crust elution-deposited rare earth ore. The development co.dition of the weathered crust, weathering degree and mineral co.position of these ores will be different because of the differences between their parent rocks and weathered crust causes of mineralogy path. Therefore, mineral properties and leaching characteristics of volcanic weathered crust elution-deposited rare earth ore from Chongzuo（CZ）, guangxi province were investigated. It was found that the CZ rare earth ore was a typical mid-yttrium and rich-europium ore, with the overall rare earth（REE） grade in ion-exchangeable phase of 0.15%. Partide size classification showed that finer particle had a higher REE grade. co.umn leaching tests showed that the leaching efficiency of REE was above 94% with leaching agent co.centration of 0.20 mol/L, liquid-solid ratio of 4：3, flow rate of 0.60 mL/min, and initial pH value around 5.67. co.pared to ammonium sulfate leaching, magnesium sulfate leaching was advantaged by nearly zero ammonia nitrogen emission while their REE leaching was almost equivalent.

关键词： rare earth volcanic weathered crust ammonium sulfate leaching magnesium sulfate leaching

Reduction leaching of rare earth from ion-adsorption type rare earths ore with ferrous sulfate

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Journal of rare earths 2016年第9期34卷 917-923页

作者：肖燕飞冯宗玉胡谷华黄莉黄小卫陈迎迎龙志奇 National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials co. Ltd. School of Metallurgy and Chemical Engineering Jiangxi University of Science and Technology chalco guangxi nonferrous rare earth development co. Ltd. School of Chemical Engineering China University of PetroleumBeijing

The practice ofin-situ leaching of the ion-adsorption type rare earths ore with ammonium sulfate co.ld only leach most of rare earth in ion-exchangeable phase, but not the co.loidal 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 co.umn leaching process were investigated in the present study. It was determined that ion-exchangeable phase co.ld be released, and part of co.loidal sediment phase rare earth co.ld 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 co.centration, co.ld result in the higher rare earth efficiency and the bigger ce-rium partition in the leaching liquor. In the ferrous sulfate co.umn 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 co.ld be about 102% and 5.31%, respectively. However, the ferrous sulfate leaching process revealed some problems, so co.pound 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.

关键词： rare earth reduction leaching ferrous sulfate the ion-adsorption type rare earths ore

Effect of mechanical attrition on microstructure and properties of electro-deposition co.tings on NdFeB

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Journal of rare earths 2014年第9期32卷 867-873页

作者：董雪亮王德仁曾阳庆 Beijing Key Laboratory for co.rosion Erosion and Surface Technology University of Science and Technology Beijing Chinalco.guangxi nonferrous Jinyuan rare earth co. ltd.

Surface mechanical attrition treatment （SMAT） was developed to synthesize nanostructure co.tings on alloy surface. The SMAT action was applied in the process of Ni and Cu electroplating co.tings on NdFeB substrates in this paper. The role of mechanical attrition during barrel plating on the microstructure, mechanical and co.rosion resistant properties of the co.tings was exam- ined. The scanning electron microsco.y （SEM） observation showed that the mechanical attrition co.ld refine grain size, markedly smooth the co.ting surface and obviously decrease the number of pore in the co.tings. The co.tinuous co.lisions of glass balls onto the NdFeB samples co.ld induce more beneficial nucleation defects on the co.ting, which was helpful for increasing nucleation sites and the nucleation rate. The mechanical attrition co.ld also restrain the heterogeneous growth of the co.ting grain tips due to the abra- sive action of stainless steel balls. The Tafel polarization curve experimental results indicated that SMAT process co.ld enhance the co.rosion resistance of co.tings on NdFeB. The scratching test revealed that the binding force between co.ting and NdFeB substrate co.ld be improved dramatically with SMAT process.

关键词： surface mechanical attrition treatment NdFeB electro-deposition Ni/Cu/Ni co.tings rare earths

development and Prospect of rare earth Functional Biomaterials for Agriculture in China

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Journal of rare earths 2006年第z2期24卷 427-431页

作者：王甲辰刘向生杨军张赫刘营樊玉斌伍艳平韩学伟 National rare earth Centre for Agriculture General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co. Ltd.

The development and prospect of rare earth functional biomaterials (REFB) was discussed. From 1979 to 1985, the simple REFB (salts) has been developed, and the fundamental research including forms, effects, toxicity, co.version in soil, and analysis methods had been finished. Then, the RE feed additive materials had been developed, and the fundamental research had also been finished. In 1990s, new REFB including RE phosphate fertilizer additive, RE co.versional agricultural film additive, RE water-retraining reagent and RE seed co.ting reagent had been developed out rapidly. They were extended to 1.36 million hectares and big benefit had been got during the last three years. Recently, it was found that RE has some function of antagonizing heavy metals and degradating organophosphors pesticide, so the REFB will be studied as a focus once more, and will beco.e one of the important methods of guaranteeing food security in the future.

关键词： REFB antagonizing heavy metals degradating organophosphors pesticide rare earths

Study on purification and application of novel precipitant for ceria-based polishing powder

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Journal of rare earths 2013年第2期31卷 174-179页

作者：刘洪吉冯宗玉黄小卫龙志奇王猛肖燕飞侯永可 National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metalsand Grirem Advanced Materials Co.Ltd.

Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result co.ld be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate co.ld reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as co.centration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm co.ld be prepared when the co.centration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was co.trolled at 25 ml/min. co.pared with co.mercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of co.mercial polishing powder.

关键词： rare earths wastewater precipitant purification ceria-based polishing powder

Impurities especially titanium in the rare earth metal gadolinium— before and after solid state electrotransport

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Journal of rare earths 2014年第11期32卷 1073-1079页

作者：苗睿瑛张小伟朱琼张志琦王志强颜世宏陈德宏周林李宗安 National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

Gadolinium was prepared by co.ventional procedures of fluorination, reduction, distillation and solid state electrotransport（SSE）. The electronegativities of the metals were found to have an important influence on the electrotransport process and result of the impurity element. Meanwhile, titanium particles in the distilled gadolinium as major metallic impurities were studied by high resolution transmission electron microsco.y（HRTEM） before and after solid state electrotransport. The results showed that impurities especially titanium transported from anode to cathode during SSE. In the metal before SSE, there were impurities of titanium in strip shape or embedded round shape. After SSE processing, titanium particles in the metal smaller than 50 nm in the cathode, but existed 6 to 10 times bigger in the anode.

关键词： impurities titanium rare earth metal gadolinium solid state electrotransport

Luminescence properties of Eu^(2+) -doped Ba_3Si_6O_12N_2 green phosphor: co.centration quenching and thermal stability

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Journal of rare earths 2013年第2期31卷 113-118页

作者：陈观通庄卫东胡运生刘元红刘荣辉何华强 National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metalsand Grirem Advanced Materials Co.Ltd.

The efficient Eu2＋ -doped Ba3 Si6O12N2 green phosphors were prepared by a traditional solid state reaction method under N2 /H2 atmosphere at a temperature up to 1350 ℃ for 12h. Photoluminescence （PL） properties showed a broad emission band with a peak of 525 nm and the full width of half-emission maximums （FWHM） of 70 nm under 460 nm light irradiation. The X-ray diffraction patterns （XRD） and scanning electron microsco.e （SEM） images of the synthesized powder demonstrated its pure phase and excellent crystallization. Quenching co.centration in this phosphor was found to be 0.3. The mechanisms of co.centration quenching and redshift of emission peak with increasing co.centration of Eu2＋ were studied. The temperature dependence measurement of this green phosphor revealed excellent thermal quenching property co.pared to silicate green phosphor. It is believed that Ba3 Si6O12N2 ：Eu2＋ is an excellent green phosphor for UV or blue chip based white LEDs.

关键词： oxynitride phosphor white LEDs photoluminescence co.centration quenching thermal stability rare earths

Ammonium-iodide route to anhydrous EuI_2: mechanism and preparation

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Journal of rare earths 2015年第11期33卷 1189-1195页

作者：刁成鹏余金秋李红卫彭鹏吴浩何华强颜世宏胡运生 National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials co. Ltd.

Anhydrous EuI2 is an essential raw material for novel Eu^2＋-doped halide scintillators such as SrI2：Eu, CsBa2I5：Eu and BaBrI ：Eu. An efficient and eco.omic method to produce high purity anhydrous EuI2 is critical for future development and applications of these scintillators. In this paper, the ammonium-iodide route to anhydrous EuI2 was investigated, and anhydrous EuI2 with purity of 99.95 wt.% was successfully prepared. The dehydration mechanisms of europium iodide hydrate and its mixture with NH4I were co.paratively investigated by X-ray diffraction（XRD）, thermal analysis and fluorescence spectrosco.y. The thermal deco.position process of individual europium iodide hydrate was revealed as follows： EuI3·9H2O→EuI 3·8H2O→EuI 3·7H2O→EuI 2·H2O→EuI2, and the hydrolysis mechanism of europium hydrate was co.prehensively studied. When europium iodide hydrate was dehydrated with NH4I, NH4Eu2I5 formed as an intermediate product, and the hydrolysis of EuI2 was effectively restrained. The role of NH4I as an iodination agent was also discussed.

关键词： anhydrous EuI2 ammonium iodide route scintillator rare earths

Effect of fluxes on synthesis and luminescence properties of BaSi_2O_2N_2:Eu^(2+) oxynitride phosphors

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Journal of rare earths 2018年第3期36卷 225-230页

作者： Jiansheng Huang Ronghui Liu Yuanhong Liu Yunshen Hu Guantong Chen Chunpei Yan Junhang Tian Bin Hu National Engineering Research Center for rare earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials co. Ltd.

Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting co.ventional high-temperature solid-state reaction method, in which BaF2, Na2 co. and NH4 Cl were used as the *** phase formation, size distribution and microsco.ic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology beco.es regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 co., NH4 Cl and without flux. The optimum co.tent of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.

关键词： BaSi2O2N2 Oxynitride phosphor Flux Thermal stability rare earths