2025 - Sustainable Industrial Processing Summit
SIPS2025 Volume 11. Intl. Symp on Iron and Steel, Non-ferrous, Metals, Bioextraction, Molten and Recycling
| Editors: | F. Kongoli, P. Assis, R. Alvarenga, J.A. de Castro, B. Deo, W.F. Santos Jr., S.L. de Andrade, GS. Mahobia, T. Usui, J. Antrekowitsch, A. Charitos, C. Oosterhof, M. Stelter, Z. Wang, A. Dmitriev, M.C. Gomez Marroquin, Y. Gordon, M. Naimanbayev, S. Prakash, V. Tsepelev |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2025 |
| Pages: | 298 pages |
| ISBN: | 978-1-998384-58-7 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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ELECTRICAL CONDUCTIVITY OF SOME MOLTEN CHLORIDES WITH NEGATIVE TEMPERATURE COEFFICIENTS
Alexander Salyulev1; Alexei Potapov2;1INSTITUTE OF HIGH TEMPERATURE ELECTROCHEMISTRY, URAL BRANCH OF RUSSIAN ACADEMY OF SCIENCE, Ekaterinburg, Russian Federation; 2INSTITUTE OF HIGH TEMPERATURE ELECTROCHEMISTRY, Ekaterinburg, Russian Federation;
Type of Paper: Regular
Id Paper: 141
Topic: 13
Abstract:
The electrical conductivity of the majority of molten salts increases with temperature. However, the rate of conductivity growth decreases with temperature. It is hypothesized that the electrical conductivity polytherms of all molten salts pass through their maximums in the temperature range from the melting point to the critical point [1–3]. For the majority of molten salts, the maximum of electric conductivity is difficult to achieve experimentally, because, as a rule, it is reached at the temperature when the value of the salt vapor pressure is equal to tens of atmospheres.
It is known that there is a very small number of halides that have negative temperature coefficients of electrical conductivity, starting from the melting point of salt [1–4]. One such salt is InCl3. According to Klemm et al. [4], the electrical conductivity of molten InCl3 decreases with increasing temperature in the studied range of 867–967 K (i.e., immediately after melting). Our experimental data on the electrical conductivity of molten InCl3, obtained using a specially designed hermetically sealed quartz cell of capillary type [5], in the temperature range of 862–1009 K confirm the Klemm’s information [4] on the negative temperature coefficient conductivity of the melt, but deviate by 2–7% at higher values:
k(S·cm–1) = –5.408 + 5.2114·10–2∙T – 5.6407·10–5∙T2 + 2.0028·10–8·T3.
In addition to InCl3, we have measured the electrical conductivity of molten ZrCl4 and HfCl4 for the first time. These salts exist in a liquid state only in narrow temperature ranges (68 or 17 K, respectively, from their melting points to the critical points):
ZrCl4: k·104/S·cm–1 = –2.0970·103 + 8.7463∙T – 1.2119·10–2∙T2 + 5.5819·10–6·T3
(in the temperature range studied 710–744.5 K the electrical conductivity decreases 1.8 times),
HfCl4: k·106/S·cm–1 = 735.06 – 1.9473∙T + 1.2966·10–3∙T2
(in the temperature range studied 704.5–713.5 K the electrical conductivity decreases by about 1.17 times).
The following InCl3, ZrCl4 and HfCl4 chlorides have a high vapor pressure already at the melting point (13–46 atm). These three salts form melts, which electrical conductivity falls on the descending branch of the general curve of electrical conductivity immediately after the melting [1, 2]. Possible causes of the anomalous dependence of electrical conductivity of molten salts on temperature are discussed.