NOZZLE ASSEMBLY HAVING INERT GAS DISTRIBUTOR

摘要

A refractory nozzle assembly (1) is provided that effectively prevents the accumulation of alumina deposits around its upper edge where it receives a stopper rod. The nozzle assembly includes a refractory nozzle body (7) having an upper (9) and a lower portion (11). A bore (13) extends through both the upper and lower portions that has a receiving and a discharge end for receiving and discharging molten metal. An inert gas distributor (20) circumscribes the upper portion of the nozzle body. A sleeve (40) of gas-obstructing refractory material covers the walls of the bore, and defines a seat portion at an upper portion of the bore. A metal sheath (50) substantially surrounds the outer surface of the upper portion (9). Pressurized inert gas conducted to the upper, gas permeable portion of the nozzle body by the gas-distributing assembly is guided by the gas-obstructing sleeve and the metal sheath so that it flows predominantly through the top edge of the upper portion. The resulting inert gas flow shields the seat portion of the bore from ambient oxygen, thereby preventing the accumulation of alumina deposits on the seat portion that can interfere with the ability of the stopper rod to control the flow of molten metal.