Transport numbers in the molten system NaF-KF-AlF3-Al2O3

被引:17
|
作者
Hives, Jan [1 ]
Fellner, Pavel [1 ]
Thonstad, Jomar [2 ]
机构
[1] Slovak Univ Technol Bratislava, SK-81237 Bratislava, Slovakia
[2] Norwegian Univ Sci & Technol, N-7034 Trondheim, Norway
关键词
Molten cryolite; Charge transport; Acid bath; BN cell; HITTORF METHOD; ALUMINUM; ELECTROLYSIS;
D O I
10.1007/s11581-012-0736-6
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Transport numbers in the molten system NaF-KF-AlF3 (Al2O3, CaF2) were investigated by the Hittorf method. It was confirmed that in molten cryolite, Na3AlF6, 1,010 A degrees C, the current is transported almost exclusively by the Na+ cations (t(Na+) = 0.99). When AlF3 was added to a Na3AlF6 melt, the transport number of sodium cations decreased to 0.74 at the composition corresponding to NaAlF4. In molten K3AlF6, the transport number of K+ cations equals 0.836 at 1,005 A degrees C. In melts containing both Na+ and K+, the cations contribute to the charge transport approximately in the ratio of the squares of their ionic radii. When 5 mass % of CaF2 was added to the molten NaF-KF-AlF3 system, it remarkably influenced the transport numbers of potassium and fluoride anions.
引用
收藏
页码:315 / 319
页数:5
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