The effects of LiF, MgF₂ and KF additions to the electrolyte on current efficiency were investigated during aluminium electrolysis using base NaF−AlF₃−Al₂O₃ system with a cryolite ratio of 2.5, 4% Al₂O₃ and 5% CaF₂ at 980°C in laboratory scale. The duration of each electrolysis experiment was 4 h with a graphite anode and a cathodic current density of 0.85 Acm⁻². The influences of various additives on the current efficiency of the aluminium electrolysis are compared. Additions of LiF up to 5 wt % were found to improve the current efficiency of aluminium deposition. Additions of MgF₂ had a positive effect on current efficiency and KF addition was harmful for the current efficiency. Current efficiencies for aluminium deposition were obtained when the additions of LiF mixed together with the additions of KF and MgF₂. The concentration of the alkali metals including K, Na and Li in deposited aluminium were analyzed as a function of the additives. Results are presented from a study of the influence of the additions on the cathode process. Correlations between the sodium content in aluminium with different additions and the current efficiency are discussed.

中文翻译：

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LiF，MgF2和KF添加剂对铝电解电流效率的影响

在铝电解过程中，使用冰晶比为2.5，Al ₂ O _3为4％和CaF为5％的基础NaF-AlF ₃ -Al ₂ O ₃体系研究了向电解液中添加LiF，MgF ₂和KF对电流效率的影响。₂在980°C的实验室规模下。每个电解实验的持续时间为4小时，带有石墨阳极，阴极电流密度为0.85 Acm ^-2。比较了各种添加剂对铝电解电流效率的影响。发现添加至多5wt％的LiF改善了铝沉积的电流效率。MgF _2的添加对电流效率有积极影响，而添加KF则对电流效率有害。当LiF的添加与KF和MgF ₂的添加混合时，可获得铝沉积的当前效率。分析了沉积铝中碱金属（包括K，Na和Li）的浓度与添加剂的关系。研究结果来自于添加剂对阴极工艺的影响。讨论了铝中钠含量与电流效率之间的关系。