Thermal Cleaning and Melting of Fine Aluminium Alloy Chips

Abstract

Production waste is one of the major sources of aluminium for recycling. Depending on the waste sources, it can be directly melted in furnaces, pre-cleaned and then melted, or due to the small size of the material (powder or dust) left without remelting. The latter form of waste includes chips formed during mechanical cutting (sawing) of aluminium and its alloys. In this study, this type of chips (with the dimensions not exceeding 1 mm) were melted. The obtained results of laboratory tests have indicated that even chips of such small sizes pressed into cylindrical compacts can be remelted. The high recovery yield (up to 94 %) and degree of metal coalescence (up to 100 %) were achieved via thermal removal of impurities under controlled conditions of a gas atmosphere (argon or/and air), followed with consolidation of chips at a pressure of minimum 170 MPa and melting at 750 o C with NaCl-KCl-Na 3 AlF 6 salt flux.