Dross Formation Mechanisms of Thermally Pre-Treated Used Beverage Can Scrap Bales with Different Density

摘要

Used beverage can scrap (UBC) bales can be remelted in state of the art multi-chamber furnaces. Following the recycling of baled UBC scrap in multi-chamber furnaces, a laboratory scale process route was developed for thermal pre-treatment and submerged melting of the scrap. In the present work, UBC scrap types with different densities and level of contamination are compared. The scrap types were thermally pre-treated in different atmospheres up to 823 K (550 ℃) and subsequently melted by submerging in a salt-free laboratory process. Melting was performed in pure aluminum at 1023 K (750 ℃) under protective argon atmosphere to exclude the influence of thermolysis gases and atmosphere. The impact of remaining organic contamination and oxidation products after thermal pre-treatment on dross formation were described. Results of SEM EDX analysis, as well as thermochemical calculations, were used to explain reactions between solid scrap and the liquid aluminium melt to improve recycling efficiency.