Patent ID: 7481964

Claim:
A gas discharge impeller for supplying a gas to a molten metal within a container, said impeller comprising: a rotatable hollow shaft having a bore, a first end connected to a gas supply and a second end extending upwardly into said container through an opening in the bottom of said container; the second end of said shaft including a gas discharge nozzle in fluid communication with said bore, the nozzle being adapted to be submersed in said molten metal when in use; and a drive means for rotating the shaft about its longitudinal axis; characterised in that: the rotatable shaft includes a seal for preventing leakage of said fluid through said opening in the container bottom, said seal being in direct sealing engagement with said rotatable shaft and said container to form a liquid seal there-between; and wherein said seal comprises a generally annular support and a generally annular bushing, said support including a lower portion extending through said container opening and an upper portion extending into said container, the support upper portion including a support surface to support said bushing and wherein said support and bushing are coaxially provided around the circumference of said shaft second end and wherein said bushing sealingly engages said shaft circumference.