Degreasing of aluminum turnings and implications for solid state recycling

Abstract

With the global warming being of concern, recycling of aluminum by new solid-state recycling techniques instead of conventional remelting and subsequent refining processing has been taken into account. Solid-state recycling processes such as extrusion and compaction at room or moderate temperature can result in significant energy savings. However, as aluminum scrap is normally contaminated by oil and/or organic coatings, decoating of scrap is an essential step for the solid-state recycling process. In the present study, degreasing of aluminum turnings with or without cold compaction was investigated by thermal methods and chemical treatment. A thermo-gravimetric furnace with a mass spectroscopy unit was utilized to understand the decomposing of machine oil on aluminum turnings in oxidizing atmospheres. For further comparison, degreasing of turnings by acetone followed by solid-state processing was also studied in the laboratory. The results may be used for choosing a suitable pre-treatment method for solid state recycling of aluminum scrap.