Method for treating a liquid with a gas using an impeller

摘要

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.