Current efficiency of recycling aluminum from aluminum scraps by electrolysis
(1. School of Science, Northeastern University, Shenyang 110819, China;
2. Huatian Engineering and Technology Corporation, MMC, Maanshan 243005, China;
3. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China)
2. Huatian Engineering and Technology Corporation, MMC, Maanshan 243005, China;
3. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China)
Abstract: Extracting aluminum from aluminum alloys in AlCl3-NaCl molten salts was investigated. Al coating was deposited on the copper cathode by the method of direct current deposition using aluminum alloys as anode. The purity of the deposited aluminum is about 99.7% with the energy consumption of 3-9 kW·h per kg Al, and the current efficiency is 44%-64% when the deposition process is carried out under 100 mA/cm2 for 4 h at 170 °C. The effects of experimental parameters, such as molar ratio of AlCl3 to NaCl, cathodic current density and electrolysis time, on the current efficiency were studied. The molar ratio of AlCl3 to NaCl has little effect on the current efficiency, and the increase of deposition temperature is beneficial to the increase of current efficiency. However, the increase of current density or electrolysis time results in the decrease of current efficiency. The decrease of current efficiency is mainly related to the formation of dendritic or powder deposit of aluminum which is easy to fall into the electrolyte.
Key words: aluminum recycling; aluminum alloy; current efficiency; electrolysis; chlorides molten salts