Recycling of Oxide from Dross into Aluminum Electrolysis Cells

Abstract

Today, aluminium dross is normally recycled by melting in a gas fired rotary furnace. Salt is partly used for protection against oxidation of aluminium metal and partly to enhance agglomeration of molten aluminium drops by breaking the oxide layers between them. The separated aluminium metal is then either retuned to the supplier of the dross, or sold to another costumer. The oxide on the other hand, which is mixed with salt and has to be further processed before it is sold as a low grade oxide. This paper describes how aluminum metal and oxide is separated in a plasma heated rotary furnace without the use of salt. The clue is that the plasma gas is a mixture of Ar + H2 and hence giving a reducing conditions. The oxides separated from the dross have been characterized with respect to chemical purity and physical properties, and compared to required properties for use in electrolysis.