Rotary degasser and rotor therefor

摘要

A device for dispersing gas into molten metal includes an impeller, a drive shaft having a gas-transfer passage therein, and a first end and a second end, and a drive source. The second end of the drive shaft is connected to the impeller and the first end is connected to the drive source. The impeller includes a first portion and a second portion with a plurality of cavities. The first portion covers the second portion to help prevent gas from escaping to the surface without entering the cavities and being mixed with molten metal as the impeller rotates. When gas is transferred through the gas-transfer passage, it exits through the gas-release opening(s) in the bottom of the impeller. At least some of the gas enters the cavities where it is mixed with the molten metal being displaced by the impeller. Also disclosed are impellers that can be used to practice the invention.

主权项

1. A device for releasing and mixing gas into molten metal, the device comprising:
(a) a motor; (b) a drive shaft having a first end connected to the motor and a second end, the drive shaft having a passage through which gas can travel and opening at the second end through which the gas is released; and (c) an impeller for dispersing gas into the molten metal and being connected to the second end of the drive shaft, the impeller having:
(i) a gas-release opening through which gas from the second end of the drive shaft is released;(ii) a top portion having a lower surface;(iii) a second portion below the lower surface of the top portion and connected to the lower surface, the second portion including a lower surface, a plurality of cavities and a protrusion between each of the plurality of cavities, wherein each protrusion has an edge for shearing gas as the impeller rotates, and the cavities, protrusions and edges are covered by the lower surface of the top portion; and(iv) a third portion below and connected to the lower surface of the second portion, the third portion including a plurality of second cavities and a second protrusion separating each pair of juxtaposed second cavities, wherein each second protrusion has an edge for shearing gas as the impeller rotates, and the second cavities are at least partially offset from the cavities of the second portion so that the second cavities are at least partially covered by the lower surface of the second portion; and wherein at least some of the gas released from the opening rises into the plurality of second cavities and the edges of the second protrusions shear the gas into smaller bubbles to assist in mixing the gas into the molten metal, and at least some of the gas entering the second cavities rises and enters the cavities;wherein when gas is released from the gas-release opening it rises into the plurality of cavities and the lower surface of the top portion helps to retain the gas in the plurality of cavities to help mix the gas and molten metal, and the edges of the protrusions shear the gas into smaller bubbles to assist in mixing the gas with the molten metal.