To completely separate and recover high purity primary crystal Al particles from Al alloy melt by giving a specified vibration while cooling Al alloy melt containing impurities with coolers.
Melt A of Al alloy scrap containing impurities such as Fe, Si or the like is charged into a vessel 2 within a resistance furnace 1 and plural water cooled coolers 3 having different extraction calories are dipped and then the Al alloy melt A is cooled to the intermediate temperature between liquidus and solidus, and thereby the primary crystal Al not containing any impurities are precipitated and adhered in particulate on a surface of the coolers 3. In this case, oscillation frequency or one side during oscillation of the coolers 3 is made fluctuated timewisely by a vibrator 4, or the long-period aperiodic interval and short-period aperiodic interval are alternately arranged, or a group assigning a long period intermittent oscillation and a group assigning a short period intermittent oscillation are separately set up. By such a method, the Al alloy melt having increased impurities concentrations is prevented from adherence to the high purity primary crystal Al shaken off and fallen down from the coolers 3. Thus, the high purity primary crystal Al precipitate is separated from the cooling bodies 3 and is recovered.
OTAKI MITSUHIRO
OHARA KOICHI
