2018-Sustainable Industrial Processing Summit
SIPS2018 Volume 3. Fehrmann Intl. Symp. / Molten Salt and Ionic Liquid
| Editors: | F. Kongoli, M. Haumann, P. Wasserscheid, T. Welton, M. Gaune-Escard, A. Angell, A. Riisager |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2018 |
| Pages: | 154 pages |
| ISBN: | 978-1-987820-86-7 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Investigation of the Distillation Characteristics of LiCl-Li2O Molten Electrolyte
Alexander Salyulev1; Alexei Shishkin1; Alexei Potapov1; Vladimir Shishkin1; Yurii Zaikov1;1INSTITUTE OF HIGH TEMPERATURE ELECTROCHEMISTRY, Ekaterinburg, Russian Federation;
Type of Paper: Regular
Id Paper: 104
Topic: 13
Abstract:
The metal product of the electrolytic reduction of oxide spent nuclear fuel in molten LiCl-Li<sub>2</sub>O mixtures retains about 8-30 wt% of the residual LiCl-Li<sub>2</sub>O salt. The salt occluded in the uranium metal should be removed by vacuum distillation.
The purpose of this work is to study the distillation of the LiCl-Li<sub>2</sub>O mixture (without uranium).
We have tested different distillation regimes. The distillation of LiCl-Li<sub>2</sub>O melts (3 wt.%) was carried out in quartz tubes at 750-800°C and the pressure of (1-3)*10-2 mm Hg for 30-70 min. Herewith, the initial mixture was kept in the MgO crucible. The crucible was weighed before and after the experiment. The salt remaining in the crucible and the sublimates were analyzed for Li<sub>2</sub>O content. The amount of Li<sub>2</sub>O was determined by titration of the aqueous solutions of the salts with a pH meter, and also by ICP-AES.
The results of our studies do not confirm the conclusions of ref. [1] on the significant co-evaporation of hardly volatile lithium oxide together with more volatile LiCl during distillation.
In our experiments, the fraction of evaporated lithium oxide remained insignificant (less than 1-3%), regardless of the fraction of evaporated LiCl (25-95%).
The loss of large amounts of Li<sub>2</sub>O from the initial mixture of LiCl-Li<sub>2</sub>O is possible either with spattering of the melt in the case of rapid evaporation of LiCl, or as a result of a side reaction of the uranium metal oxidation with Li<sub>2</sub>O in residual salts: U + 2Li<sub>2</sub>O * UO<sub>2</sub> + 4Li. This reaction becomes probable at temperatures above 850-900°C due to the evaporation of metallic lithium at such temperatures.