Abstract: An improved impeller head is provided for treating molten metals and other liquid systems with a gas. A multiple-vaned impeller head is adapted for mounting on a hollow impeller shaft for rotation within the liquid The edges of the impeller vanes are extended by an axial groove which intercepts the hub and the vanes of the impeller head. Extension of the trailing edge of the vanes creates greater turbulence in the liquid as the impeller is rotated in the liquid and increases the impeller's efficiency. The impeller vanes may also have canted leading surfaces which create an upward axial flow of liquid to discourage formation of a surface vortex. Multiple impellers may also be mounted on a shaft in the vessel and the gas may be introduced remotely.

Abstract: An improved impeller head is provided for treating molten metals and other liquid systems with a gas. A multiple-vaned impeller head is adapted for mounting on a hollow impeller shaft for rotation within the liquid. The edges of the impeller vanes are extended by an axial groove which intercepts the hub and the vanes of the impeller head. Extension of the trailing edge of the vanes creates greater turbulence in the liquid as the impeller is rotated in the liquid and increases the impeller's efficiency. The impeller vanes may also have canted leading surfaces which create an upward axial flow of liquid to discourage formation of a surface vortex. Multiple impellers may also be mounted on a shaft in the vessel and the gas may be introduced remotely.

Abstract: The filtration of molten metal is obtained by providing the filtration medium, which may, for example, be formed of a granulated material, with a conductive coating or conductive particles. Electrical energy is coupled across the filter to create a current flow through the conductive material. The magnitude of the current generates heat of a level sufficient to maintain the metallic material being filtered in the molten state as it passes through the filter medium. The granules may be covered with a conductive coating or conductive particles. In an alternative embodiment, the granules may be formed of a material, such as silicon carbide, which is capable of being inductively heating to maintain the metallic material being filtered in the molten state as it is passed through the filter medium.