Determination of RE2Ce2O7 pyrochlore phases from monazite-allanite ores

被引:24
作者
Bezerra Lopes, Francisco Wendell [1 ]
de Souza, Carlson Pereira [1 ]
Vieira de Morais, Antonio Marcilio [1 ]
Dallas, Jean-Pierre [2 ]
Gavarri, Jean-Raymond [2 ]
机构
[1] Univ Fed Rio Grande do Norte, DEQ, PPGEQ, LTRC, BR-59072970 Natal, RN, Brazil
[2] Univ Sud Toulon Var, CNRS, UMR 6242, IM2NP, F-83957 La Garde, France
关键词
Cerium lanthanum oxide; Pyrochlore phase; Hydrometallurgy; Leaching process; X-ray diffraction; Rietveld structural refinement; TEMPERATURE; SYSTEMS; ND;
D O I
10.1016/j.hydromet.2009.02.007
中图分类号
TF [冶金工业];
学科分类号
0806 ;
摘要
By using a specific chemical process, it was possible to extract a pyrochlore RE2Ce2O7 phase directly from waste materials composed of allanite-monazite minerals mixed with aluminosilicate and other phosphate phases. The pyrochlore phase is well known for its interesting thermal properties. Monazite (Ce, La, Nd, Pr, Th) PO4 is a mineral rich in rare earth elements (cerium, lanthanum). Polycrystalline waste samples were submitted to a series of chemical treatments followed by alkaline fusion. After reaction with nitric acid and addition of oxalic acid, soluble ions were separated from insoluble ones, resulting in rare earth oxalate intermediate phases. After filtration, these oxalate phases were dried and heated at 900 degrees C. The resulting solid was analyzed by transmission electron microscopy and X-ray diffraction. These analyses showed that the as-extracted phase was composed of a complex RE23+Ce24+O72- system, rich in cerium and lanthanum along with other rare earth elements (RE). The mean crystal structure of these complex phases was determined from Rietveld diffraction profile refinement: it was close to pyrochlore structure La2Ce2O7 with space group Fd3m. The refined cell parameter a, and the lattice distortion c, calculated from profile broadening analyses, were related to the presence of RE3+ ions occupying the La site. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.
引用
收藏
页码:167 / 172
页数:6
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