aluminum reduction
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JOM ◽  
2022 ◽  
Author(s):  
Jing Shi ◽  
Yuchen Yao ◽  
Jie Bao ◽  
Maria Skyllas-Kazacos ◽  
Barry J. Welch ◽  
...  

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7419
Author(s):  
Pavel Arkhipov ◽  
Olga Tkacheva

A new way to reduce the energy consumption during the operation of powerful aluminum reduction cells is suggested via reducing the resistance of the electrolyte, i.e., increasing its electrical conductivity. The electrical conductivity of molten cryolite mixtures NaF-AlF3-CaF2-Al2O3 with cryolite ratio (CR) of 2.1–3.0 and content of CaF2 and Al2O3, up to 8 wt%, was measured at the temperatures from liquidus to 1300 K. Based on the experimental results, a multifunctional equation for the electrical conductivity of oxide-fluoride cryolite melts was evaluated. The experimental and calculated values of the electrical conductivity agree within 1.5%. The activation energy of the electrical conductivity of the NaF-AlF3-CaF2-Al2O3 melts was estimated. The activation energy of electrical conductivity for molten NaF-AlF3 mixtures with CR 3.0 and 2.1, determined by the most mobile cations Na+, increased from 15.8 kJ/mol up to 18.5 kJ/mol. It was found that CR had a greater impact on the activation energy than the changes in the Al2O3 or CaF2 concentrations. Based on the ratio of the activation energies of the electrical conductivity and the viscous flow, the correlation between the electrical conductivity and viscosity of molten cryolite mixtures NaF-AlF3-CaF2-Al2O3 was illustrated.


Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1431
Author(s):  
Andrey Yasinskiy ◽  
Sai Krishna Padamata ◽  
Srecko Stopic ◽  
Dominic Feldhaus ◽  
Dmitriy Varyukhin ◽  
...  

Electrochemical decomposition of spent catalyst dissolved in molten salts is a promising approach for the extraction of precious metals from them. This article reports the results of the study of aluminum electrowinning from the xLiF–(1-x)AlF3 melt (x = 0.64; 0.85) containing 0–5 wt.% of spent petroleum Pt/γ-Al2O3 catalyst on a tungsten electrode at 740–800 °C through cyclic voltammetry and chronoamperometry. The results evidence that the aluminum reduction in the LiF–AlF3 melts is a diffusion-controlled two-step process. Both one-electron and two-electron steps occur simultaneously at close (or same) potentials, which affect the cyclic voltammograms. The diffusion coefficients of electroactive species for the one-electron process were (2.20–6.50)∙10−6 cm2·s–1, and for the two-electron process, they were (0.15–2.20)−6 cm2·s−1. The numbers of electrons found from the chronoamperometry data were in the range from 1.06 to 1.90, indicating the variations of the partial current densities of the one- and two-electron processes. The 64LiF–36AlF3 melt with about 2.5 wt.% of the spent catalysts seems a better electrolyte for the catalyst treatment in terms of cathodic process and alumina solubility, and the range of temperatures from 780 to 800 °C is applicable. The mechanism of aluminum reduction from the studied melts seems complicated and deserves further study to find the optimal process parameters for aluminum reduction during the spent catalyst treatment and the primary metal production as well.


Author(s):  
Dmitry A. Balaev ◽  
Sergei V. Semenov ◽  
Sergei N. Varnakov ◽  
Evgeniy Yu. Radionov ◽  
Yaroslav Al. Tretyakov

The magnetic properties of steel of a structural element of an aluminum reduction cell have been investigated in the temperature range of 300–900 K. The analysis of the temperature dependence of the saturation magnetization MS(T) showed (i) the applicability of the Bloch’s 3=2 law and a reason- able value of the Bloch’s constant for steel and (ii) the quadratic dependence MS(T) (1 - T2) in the temperature range of 380–700 K.


Author(s):  
Yanfang Zhang ◽  
Qiaoyun Liu ◽  
Dengpeng Chai ◽  
Qingjie Zhao ◽  
Yueyong Wang ◽  
...  

2021 ◽  
Vol 54 (11) ◽  
pp. 49-54
Author(s):  
Jing Shi ◽  
Yuchen Yao ◽  
Jie Bao ◽  
Maria Skyllas-Kazacos ◽  
Barry J. Welch ◽  
...  

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