Abstract: A refractory plate-frame assembly for use in a sliding closure unit includes a frame having therein a recess and a refractory plate positioned within the recess. A flexible band is mounted within the recess about the periphery of the refractory plate. A tightening device is mounted in the frame and is selectively operable from the exterior thereof to tighten the band about the periphery of the plate and thereby securely mount the plate within the recess, and alternatively for loosening the band from the periphery of the plate, whereby the plate may be removed from the band and the frame.

Abstract: A sliding closure unit includes at least two refractory plates having therethrough discharge openings, the plates abutting on respective planar sliding surfaces. A generally U-shaped recess is formed in each sliding surface, each recess including a pair of free arms extending toward the other recess. The recesses are dimensioned such that, when the plates are in the open position thereof, the arms of the recesses overlap, thereby forming a connected recessed area encircling the discharge openings. One of the plates has therethrough a channel opening into the recessed area and adapted to be connected to a vacuum source, thereby making it possible to prevent air from contacting molten metal being discharged through the discharge openings.