The present invention relates to a system for adding powder to molten metal and for mixing the powder into the molten metal. The system includes a powder tank and a mixing chamber (4) with a varying cross section in a direction of flow. The Mixing chamber includes a powder inlet, a molten metal inlet, an outlet (14) providing a flow path for a mixture for molten metal and powder between the mixing chamber (4) and a crucible (5). At least one deflecting portion is located opposed the inlet. A flow path between the powder tank (1) and the powder inlet leads the powder into the mixing chamber (4). Furthermore, the invention relates to a system for the production of aluminium, including a crucible (5) and a crucible cover (7) defining a crucible cavity and a drain pipe (8). The system includes the powder tank (1), the mixing chamber (4) inside the crucible cavity, the mixing chamber (4) including a powder inlet, a molten metal inlet, an outlet (14) providing a flow path for a mixture for molten metal and powder between the mixing chamber (4) and the crucible (5). At least one deflecting portion is opposing the inlet. A flow path between the powder tank (1) and the powder inlet leads powder into the mixing chamber (4).