Editors: | Kongoli F, Gaune-Escard M, Turna T, Mauntz M, Dodds H.L. |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2016 |
Pages: | 390 pages |
ISBN: | 978-1-987820-24-9 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
The electrolytic extraction and refining of zirconium and hafnium processes need data on the electrical conductivity of ZrCl4 and HfCl4 solutions in molten alkali chlorides. In general, these systems are characterized by a high saturated vapor pressure. However, there are two concentration "windows" (the high temperature window, 0-30 mol % MCl4, and the low temperature one, 55-70 mol % MCl4) applicable for technical purposes because the vapor pressure of these melts is below the atmospheric one.
In this work the electrical conductivity of ZrCl4 solutions in molten LiCl, NaCl, KCl, CsCl and NaCl-KCl (1:1) and HfCl4 solutions in molten KCl were measured for the first time. The measurements were carried out using quartz U-shaped capillary type cells with Pt- or W-electrodes at the concentrations of 0-30 mol % MCl4 and temperatures 600-850 0C.
It was found that conductivity of the ionic melts ranges from 0.6 to 6 S/cm, increases with increasing the temperature, decreases with increasing MCl4 concentration and reduces from Li+ to Cs+, depending on the salt-solvent cation size.
High volatile molecular ZrCl4 and HfCl4 are held in molten alkali chlorides environment as a part of strong complex anions ZrCl62- and HfCl62-.
The established regularities in the electrical conductivity changes are discussed.
This work was supported by the Ministry of Education and Science of the Russian Federation, project No. 14.607.21.0084 (RFMEFI60714X0084).
Keywords: Electrical conductivity, melts, alkali metal chloride, ZrCl4 and HfCl4 solutions.