A. N. Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, Moscow, Russia:

G. V. Kostikova, Senior Researcher
Yu. S. Krylov, Senior Researcher
A. Yu. Tsivadze, Director
E. V. Salnikova, Researcher

Moscow State University of Fine Chemical Technologies, Moscow, Russia:

O. A. Kutepova, Post-Graduate Student

There was carried out the systematic study of Sc, Th, Fe and Zr extraction from chloride solutions in the presence of different salting-out agents. The composition of extracted compounds was determined for extraction systems of TiAPh – HCl – LiCl with dilution method. It is shown, that in the presence of LiCl, the maximum value of separation coefficient of Sc/Th (7,24) is reached when [LiCl] = 3 M. At the same time, all over the concentration range of LiCl, the separation coefficients of Zr/Sc are small. Usage of NH4Cl as salting-out agent is not efficient because of the following reasons:
— due to low values of distribution coefficients of Sc, Th, and Zr;
— due to low solubility of NH₄Cl in 3 M of HCl.
During the usage of CaCl₂ as salting-out agent, the maximum value of separation factor of Sc/Th is 6.5 for concentration of [CaCl₂] = 1.5 M, while [CaCl₂] = 2 M separation factor of Zr/Sc is equal to 6.1. In case of joint presence of LiCl – CaCl₂, extraction systems are relatively selective for the separation of Zr. When concentrations in the aqueous phase are [LiCl] = 1 M and [CaCl₂] = 1.5 M, the separation coefficients of Sc/Th Zr/Sc are equal to 4.6 and to 11.52 respectively, which makes possible to use such extraction system during the process of Sc refining with method of full irrigation. It is shown, that in the presence of AlCl₃, the usage of TiAPh for extraction purification of Sc from Th and Zr is not sufficiently efficient due to practically simultaneous transition of all three elements in organic phase. The salting-out ability in case of scandium extraction with TiAPh from hydrochloric acid solutions was increased in the following range: NH₄Cl < CaCl₂ < AlCl₃ < LiCl. The carried out studies have shown that extraction of TiAPh from hydrochloric acid solutions in the presence of salting-out agents could not find the conditions, which will make possible to undertake a process of simultaneous purification of Sc from Zr and Th with high separation factors on a limited number of extraction stages.

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