Recovery of metallic aluminum from secondary aluminum dross by physical enrichment and molten salt electrolysis

Secondary aluminum dross is a kind of solid waste produced in the aluminum industrial production process, containing metallic aluminum, alumina, aluminum nitride and other substances. In this paper, we enriched metallic aluminum in aluminum dross by ball milling and screening, and study the particle size distribution of aluminum dross and the separation law of aluminum in the ball milling process. The results showed that ball milling made the metallic aluminum in aluminum dross larger in particle size, while other components became finer. The optimal conditions were ball milling for 3 h and screening. Material characterization studies have revealed that the metallic aluminum content in aluminum dross with a particle size range of 97~150 μm was 24.51%. In contrast, metallic aluminum's mass accounted for 41.40% of the aluminum's total mass in the as-received dross. The aluminum dross was electrolyzed under the optimal conditions of ball milling and screening in cryolite molten salt, and the mass fractions of Al and Si in the electrolysis products were 97.3% and 1.6% by XRF analysis, respectively. The metal yield of the aluminum alloy product obtained by the electrolysis was 45.89%, and the current efficiency was 46.06%.