Abstract: Over the past few decades, aluminium alloys have been used in a large number of applications in packaging, transport, aerospace and other areas, making them the second most important metallic material after steel. Because of their good corrosion resistance, aluminum alloys can be recycled after reaching the end of their useful life. The recycling of aluminum alloys has the double important significance of saving resources and environmental protection. The traditional cryolite electrolytic alumina process consumes a lot of energy and releases a lot of greenhouse gases. Remelting and recycling of end-of-life aluminum alloys can reduce energy consumption and carbon emissions, but this method affects the purity of the recycled aluminum. Recycling of scrap aluminum by molten salt electrolysis not only reduces energy consumption and carbon emissions, but also improves the purity of the recycled aluminum. In this work, AlCl3-NaCl-LiCl-KCl was used as the electrolyte for aluminum deposition on pure aluminum sheet with scrap aluminum alloy as the anode. The effect of experimental conditions such as current density, electrolysis temperature, and electrolysis time on the recovered metallic aluminum products were investigated, and the electrochemical mechanism of aluminum recovery in AlCl3-NaCl-LiCl-KCl molten salt was analyzed. It was shown that the current efficiency in scrap aluminum alloy could reach 97.3% and the purity of aluminum obtained was about 99.4wt% under the conditions of electrolysis temperature of 100℃, current density of 30 mA/cm2, and electrolysis for 3 h. The cyclic voltammetry curve indicated that only aluminum was involved in the reaction process, and the deposition potential of aluminum was about -0.3 V (vs. Al), and the scrap aluminum alloy dissolved under the action of the current and reacted with AlCl4- in the electrolyte to form Al2Cl7-, and Al2Cl7- near the cathode gained electrons to form an aluminum deposition layer on the cathode surface.

Key words: waste aluminum recycling, low temperature molten salt, aluminum electrodeposition, current efficiency

摘要： 铝合金的回收再利用具有节约资源和环境保护的双重重要意义。采用AlCl3-NaCl-LiCl-KCl作为电解质，以废旧铝合金为阳极，在纯铝片上进行铝的沉积，研究了电流密度、电解温度和电解时间等实验条件对回收金属铝产物的影响规律，并分析了AlCl3-NaCl-LiCl-KCl熔盐中铝回收的电化学机理。研究表明，废旧铝合金在电解温度为100℃，电流密度为30 mA/cm2，电解3 h条件下，电流效率可达97.3%，得到的铝纯度约为99.4wt%。循环伏安曲线表示，反应过程中仅有铝参与反应，铝的沉积电位为-0.3 V (vs. Al)左右，废旧铝合金在电流作用下发生溶解，与电解液中AlCl4-反应生成Al2Cl7-，阴极附近的Al2Cl7-得到电子，在阴极表面形成铝的沉积层。

关键词: 废铝回收, 低温熔盐, 铝电沉积, 电流效率