Recovery of aluminum from waste aluminum alloy by low-temperature molten salt electrolysis

Large amounts of industrial waste discharge have serious implications for the environment. The production of coarse Al-Si alloy by carbothermal reduction is considered to be one potential method for making use of industrial aluminiferous waste slag. Here, we discuss the influence of different processing parameters on electrolytic refining of aluminum alloy and investigate the mechanism of extracting Al from coarse Al-Si alloy in a low-temperature molten salt system. Aluminum is obtained with the use of coarse Al-Si alloy as a soluble anode in the AlCl3-NaCl-KCl molten salt system. The current efficiency reached over 94% when the electrolysis temperature was 170 ℃, the current density was 30 mA/cm2 and electrolysis was performed for 1.5 h. In the electrolysis process, Al in the coarse Al-Si alloy was present in the form of Al2Cl7− and AlCl4−, which precipitated at the cathode. The purity of aluminum electrodeposited on the aluminum cathode was 99.3%.