Closure devices for metallurgical and like vessels

Claim 1

In a vessel for containing and discharging molten material, having a gas-tight annex chamber offset from but communicating laterally with the interior of the vessel, the bottom of which chamber being not substantially above the bottom of the vessel interior and being provided with a discharge orifice for the downward discharge of the molten material, and also having a refractory, or refractory-clad, stopper rod extending down through the chamber and movable in a substantially vertical direction between a lower closed position in which its lower end closes the orifice and an upper open position in which its lower end is spaced from the orifice, the rod extending slidably through the roof of the chamber so as to be capable of being raised and lowered by means external to the chamber and being provided with a gas-tight gland, the improvement comprising an enlarged recess formed in the roof of the chamber surrounding the stopper rod, the volume of the recess being substantially greater than the volume enclosed by the gland above the recess and communicating therewith, whereby gas trapped above the level of molten material in the annex chamber is compressed primarily within the enlarged recess as the level of vessel according to claim 1 wherein the gland comprises a bellows into which the upper end of the rod extends, said bellows being sealed to the rod and to the roof of the chamber.