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Combustion synthesis and characterizations of Sm2O3 doped zirconolite-rich waste forms with CuO as oxidant

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Journal of Rare Earths 2019年第12期37卷 1359-1365页

作者： Kuibao Zhang Dan Yin Zongsheng He Jiali Xue Wenwen Zhao Haibin Zhang State Key Laboratory of Environment-friendly Energy Materials Southwest University of Science and TechnologyMianyang 621010China National Defense Key Discipline Lab of Nuclear Waste and Environmental Safety Southwest University of Science and TechnologyMianyang 62W10China Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China

zirconolite is one of the most important matrix materials for nuclear waste *** this study,Sm was employed as the surrogate of trivalent ***-doped zirconolite-rich waste forms were readily prepared by combustion synthesis(CS)using CuO as the *** different schemes with or without Al2O3 as the charge compensator were carried out *** results demonstrate that Al2O3 addition results in complex phase *** the other hand,the samples without Al2O3 addition show desirable products of zirconolite and *** EDX analysis shows that Sm is concurrently incorporated into the Ca and Zr sites of zirconolite,which transforms to pyrochlore structure with high Sm2O3 *** aqueous durability of representative Sm-doped sample(Sm-0.6)was *** 42 days normalized leaching rate of Sm is as low as 6.41×10-7 g/(m2 d),which exhibits high durability of Sm-doped sample.

关键词： Combustion synthesis Sm2O3 zirconolite Pyrochlore Aqueous durability Rare earths

Solid-state reaction synthesis and chemical stability studies in Nd-doped zirconolite-rich ceramics

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Journal of Rare Earths 2018年第5期36卷 492-498页

作者： Dan Yin Kuibao Zhang Le Peng Zongsheng He Yuan Liu Haibin Zhang Xirui Lu State Key Laboratory Cultivation Base for Nonmetal Composite and Foundational Materials Southwest University of Science and Technology Mianyang 621010 China National Defense Key Discipline Lab of Nuclear Waste and Environmental Safety Southwest University of Science and Technology Mianyang 621010 China Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China

In this study, Nd-bearing zirconolite-rich ceramics were prepared by solid-state reaction process using CaF2,ZrO2, Ti,TiO2, Fe2 O3 and Nd2O3 as the raw materials. Neodymium was used as trivalent actinide surrogate and designed to substitute the Ca and Zr sites of zirconolite with general stoichiometry of Ca1-xZr1-xNd2 xTi2O7（0≤x≤0.3）. Density of Fe-Nd-O sample reaches a maximum value of 4.13 g/cm^2 after being sintered at 1325 ℃ for 42 h. Three major phases, namely zirconolite, perovskite and pseudobrookite, are observed in all these samples. The EDX result shows that Nd2O3 can be successfully incorporated into the lattice structure of the prepared zirconolite-rich minerals and replace the Ca sites of zirconolite and perovskite with Fe3＋ as the charge-compensating ion. Furthermore, the thermal conductivities are all in the range of 1.51-1.67 W/（m·K）. The normalized elemental leaching rates of Ca and Nd in the Fe-Nd-0.2 sample keep in low values of 6.20 × 10^-2 and 4.86 × 10^-4 g/（m^2·d） after 42 d.

关键词： zirconolite Perovskite Pseudobrookite Nd2O3 Chemical stability Rare earths

In situ U-Pb and Nd-Hf-(Sr) isotopic investigations of zirconolite and calzirtite

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In situ U-Pb and Nd-Hf-(Sr) isotopic investigations of zirco...

Study on the zirconolite Solidification of Simulated Np/Pu Radioactive Incineration Ash

中国科学院地质与地球物理研究所第十届(2010年度)学术年会

作者： Roger H.Mitchell Fabio Bellatreccia Department of Geology Lakehead UniversityOntarioCanadaP7B 5E1 Dipartimento di Scienze Geologiche Universita degli Studi Roma TreLargo S.Leonardo Murialdo 100146 RomaItaly

Although the calcium-and titanium-bearing zirconsilicates,zirconolite and calzirtite,are common minerals in carbonatites little is known regarding their trace element or isotopic *** data indicate that they can have significant contents of U,Pb,Nb,Ta,Zr,Hf,rare earth elements(REEs),minor Sr and low Rb/Sr and Lu/Hf *** compositions indicate that they have potential for U-Pb age determination together with Nd-Hf and possibly Sr isotopic *** this study,zirconolite and calzirtite from carbonatites occurring at Phalaborwa(South Africa),Prairie Lake(Canada),Afrikanda and Kovdor (Kola,Russia),Guli(Siberia,Russia)and Jacupiranga(Brazil)were selected for an isotopic analysis by in situ *** microprobe analyses using a CAMECA 1280 ion microprobe show that reliable Pb-Pb ages can be obtained from these minerals as they have extremely high U concentrations,coupled with negligible common *** these minerals have low Rb/Sr ratios,their low Sr concentrations,in most cases, render in situ Sr isotopic analyses *** contrast,their high Sm,Nd and Hf concentrations,with generally low Lu/Hf ratios,permit precise in situ isotopic analysis of Nd and Hf.

关键词： U(Pb)-Pb age Nd-Hf-(Sr)isotopes zirconolite Calzirtite In situ analysis Carbonatite

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矿物学报 2013年第S1期33卷 108-108页

作者： WEN Mingfen WANG Jianchen Institute of Nuclear and New Energy Technology Tsinghua University

High level waste is nuclear energy generated during the application process ,which is the greatest and the most difficult to management the waste. Proper treatment and disposal of it has already become a worldwide problem, and has become one of the key factors of restricting nuclear energy for sustainable development. zirconolite (CaZrTi2O7) is one of the most stable mineral on the Earth and actinide major parasitic phase, therefore, it is widely used to solidify actinides separated from high level radioactive waste. In this paper, the zirconolite solid solution was synthesized by high temperature solid-stated method using a particular composition of simulated Np/Pu radioactive incineration ash (SRIA). The phase composition has been investigated by X-ray diffraction (XRD), the calcined temperature gained according to thermogravimetry scanning calorimeter (TG-DSC) analysis. Anti-leaching performance has also been researched with MCC-1 method. Results show that CaZrTi2O7 can load 40% SRIA, the accumulated leaching fraction of Ca is only about 10-4 cm in 28 days at 90 ℃, the concentrations of Zr , Ti and other noble metal ions were all less than detectability of ICP-MS, the leaching rate , normalization leaching rate, and accumulated leaching fraction of all Zr , Ti and other noble ions were 10-8 cm/d, 10-8 g/cm2·d and 10-7 cm, the results indicate that the zirconolite solidification has excellent chemical durability.

关键词： zirconolite solidification simulated Np/Pu radioactive incineration ash leaching performance

Phase relations,microstructure,and valence transition studies on CaZr1-xCexTi2O7(0.0≤x≤1.0)system

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Journal of Rare Earths 2018年第11期36卷 1184-1189页

作者： Weimin Li Faqin Dong Liang Bian Hao Zou Mianxin Song Research Center of Laser Fusion China Academy of Engineering PhysicalMianyang 621900China Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory Southwest University of Science and TechnologyMianyang 621010China Laboratory of Solid Waste Treatment and Resource Recycle Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China Hebei University of Geosciences Shijiazhuang 050000China

In this study, Ce-doped zirconolite was synthesized through high-temperature solid-state reaction at 1250 ℃ in air for 96 h. The crystal phase, microstructure and valence transition were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and X-ray photoelectron spectroscopy （XPS）. Phase relations of CaZrl xCexTi207 systems were determined by XRD analyses and Rietveld refinements. Four different phases are identified, namely zirconolite, perovskite, pyrochlore, and cerianite. The phase transformation （2M-zirconolite → 4M-zirconolite →Ce-pyrochlore） is caused by cations rearrangement as cerium content increases. The solubility limit of cerium ions in CaZrl .xCexTi207 system is estimated to be approximately 0.80. Under sintering air atmosphere, partial reduction of Ce^4＋ in Ce^3＋ is detected in Ce 3d XPS soectra, and the ratio of Ce^3＋ and Ce^4＋ significantly decreases as cerium content increases.

关键词： zirconolite Ce-pyrochlore Phase relations Valence transition Rare earths

SIMS Pb/Pb dating of Zr-rich minerals in lunar meteorites Miller Range 05035 and LaPaz Icefield 02224:Implications for the petrogenesis of mare basalt

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Science China Earth Sciences 2010年第3期53卷 327-334页

作者： HSU WeiBiao Faculty of Earth Sciences China University of Geosciences

Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.

关键词： Pb/Pb dating SIMS zirconolite and baddeleyite lunar meteorite low-Ti mare basalt