An Inverted Aluminum Electrolysis Cell Using a High Density Electrolyte and an Inert Anode - A Test of the Concept

Rolseth, Sverre; Gudbrandsen, Henrik; Thonstad, J.

doi:10.1149/05011.0251ecst

Cited by 2 publications

(1 citation statement)

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“…To reduce the liquidus temperature and gain a better operation, the electrolyte is modified by addition of aluminum fluoride, calcium fluoride and in some case other additives (2)(3)(4)(5)(6)(7)(8)(9). NaCl has been not used in industry production yet and there are fewer studies on addition of NaCl.…”

Section: Introductionmentioning

confidence: 99%

Liquidus Temperature of Molten Cryolite-Based Aluminum Electrolyte

et al. 2007

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Liquidus temperature is one of important parameters for aluminum electrolysis. In this study, a new method is introduced; the liquidus temperature is measured with one Agilent 34401A meter connected to a computer. The whole process is controlled by computer software. Firstly, liquidus temperature of NaF and NaCl are measured for comparison. The result is proved to be convenient and accurate. The range of error is ±1~1.5 at 801 to 995 . ℃ ℃ ℃ Furthermore low temperature aluminum electrolyte composition is related. The liquidus temperature measurement of the system is NaF·AlF 3 (R=2.25)-Al 2 O 3 (3%)-CaF 2 (4%)-LiF(0~6%)-NaCl(0~6%). The result showed that the liquidus temperature is reduced greatly by adding NaCl and LiF. The mathematical model obtained is T( )=947.588 ℃ -5.907×LiF(wt/%)-6.223×NaCl(wt/%). The authors expected these data are useful for industry production of aluminum electrolysis, since it can provide a scientific basis for choosing suitable low temperature aluminum electrolyte composition. IntroductionLow temperature aluminum electrolysis has been one of the most active research fields in recent years. By the introduction of low-melting baths, one might expect the increase in the current efficiency, lower energy consumption and, possibly, prolonged cell life and easier adaptation of inert electrode materials (1). The research on the liquidus temperature is one of the important premises for realization of low-melting baths.Liquidus temperature and bath temperature are important parameters in controlling an electrolytic aluminum reduction cell because their values determine the performance of the cell. The bath temperature and liquidus temperature (i.e., superheat) determine current efficiency. Although a lower superheat results in higher current efficiency, the decreased alumina solubility and alumina-solution rates occur when the superheat is too low. Operating the cell at superheats that are too low may also lead to instabilities because of metal rolling; the density difference between bath and metal decreases with decreasing temperature. Furthermore, a superheat that is too high leads to a decrease in current efficiency. Too much energy is wasted as thermal losses and anode carbon consumption increases. It is necessary to measure the liquidus temperature of cryolite-based electrolyte.To reduce the liquidus temperature and gain a better operation, the electrolyte is modified by addition of aluminum fluoride, calcium fluoride and in some case other additives (2-9). NaCl has been not used in industry production yet and there are fewer studies on addition of NaCl. The studies show that NaCl not only reduces the freezing point of cryolitic melt greatly but also increases the electrical conductivity (10, 11). In this work, the systems with NaCl were studied. ECS Transactions, 3 (38) 7-12 (2007) 10.1149/1.2806945, copyright The Electrochemical Society 7 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 192.231.202.250 Downloade...

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Section: Introductionmentioning

confidence: 99%