Device and method for melt treatment of aluminium alloys having excessive inclusions, impurities and unwanted gases to be removed, by (a) cooling the melt at an appropriate cooling rate to a temperature below the liquidus by shearing the melt associated with the introduction of at least one type of inert gases into the melt to form fine bubbles and high shear in the melt, and (b) purifying inclusions in the melt by floating them to the top surface, degassing the undesirable gases by reacting with the inert gas, and forming solid intermetallics containing impurity elements and transferring the melt mixture by the shearing device into a holding furnace, and (c) maintaining the melt in the holding furnace at a temperature below the liquidus and above the solidus temperature to settle the solid intermetallics formed by impurity elements as sediment at the bottom of the holding furnace while flowing the melt with much reduced inclusions, impurities and unwanted gases out of the holding furnace as applicable materials. The method is advantageously applicable for upgrading aluminium alloys from recycled and/or scrapped materials.