ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 10, pp. 1767!1769. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.Yu. Kuznetsov, V.V. Solov’eva, E.P. Buchikhin, A.M. Chekmarev, 2007, published in Zhurnal Prikladnoi Khimii, 2007,
Vol. 80, No. 10, pp. 1738!1740.
Conversion of Rare-Earth Metal Oxides
in Tributyl Phosphate
A. Yu. Kuznetsov, V. V. Solov’eva, E. P. Buchikhin, and A. M. Chekmarev
All-Russia Research Institute of Chemical Technology, Moscow, Russia
Mendeleev Russian University of Chemical Engineering, Moscow, Russia
Received May 2, 2007
Abstract-Dissolution of gadolinium, europium, neodymium, dysprosium, and samarium oxides to give
nitrates of these metals was studied in a system constituted by tributyl phosphate (30 vol %), tetrachloro-
ethylene (70 vol %), and NO
. The activation energy of anhydrous dissolution of gadolinium oxide was
calculated. The effect of water on the conversion efficiency of gadolinium oxide into nitrate was examined.
It is known that solvometallurgical methods for
processing of ores and secondary raw materials 
make it possible to intensify dissolution processes,
improve the selectivity of the processing techniques,
and substantially diminish, or even completely aban-
don use of water in technological processes .
Development of the solvometallurgical technolo-
gies for processing of mineral resources requires
a study of the fundamental aspects of interaction
between dissolved materials and nonaqueous systems.
The authors of  studied the oxidative dissolution
of rare-earth elements in tributyl phosphate (TBP). In
, chlorination of yttrium oxide in the system con-
stituted by dimethylformamide (DMFA) and Cl
analyzed, with the kinetic properties of the interaction
This study is concerned with the nonaqueous low-
temperature nitration of gadolinium, europium, neo-
dymium, dysprosium, and samarium oxides in the sys-
tem constituted by TBP, tetrachloroethylene (TCE),
and nitrogen dioxide.
We used TBP of chemically pure grade, prepared
by the method described in . Tetrachloroethylene
was purified by distillation .
The dissolution was studied in a temperature-con-
trolled reactor (stirring rate 8003900 rpm). It was
confirmed by preliminary experiments that these
conditions correspond to the kinetic dissolution mode.
Powders of gadolinium, europium, neodymium, dys-
prosium, and samarium oxides were prepared by
calcination of their hydroxides under identical con-
ditions at 800oC . Gadolinium oxide used in
the experiments had cubic structure.
Visible-range spectra of the organic solutions pre-
pared were recorded on a Shimadzu UV-3000 instru-
We studied the dissolution of gadolinium, euro-
pium, neodymium, dysprosium, and samarium oxides
in the system constituted by tributyl phosphate
(30 vol %), TCE (70 vol %), and NO
(1.5 M) at
40oC. The results of the experiments are shown in
Fig. 1. The conversion of rare-earth element oxides
proceeds without an induction period, with its rates in
Fig. 1. Dissolution of REE oxides in the system TBP
(30 vol %)3TCE (70 vol %)3NO
(1.5 M) at T =40oC.
(c) Concentration and (t) time; the same for Figs. 23 4.
REE: (1) Eu, (2) Sm, (3) Dy, (4) Nd, (5) Gd.