Abstract: A rotary sliding closure unit for use in a liquid melt container extends inwardly through the jacket of the container and into the lining thereof to selectively block and unblock a pouring opening of the container. The unit includes a stationary refractory plate positioned within the lining and having therethrough a flow passage in communication with the pouring opening, and a rotary refractory plate positioned in sliding abutting contact with the stationary refractory plate and having therethrough at least one flow passage to be selectively moved into and out of alignment with the flow passage of the stationary refractory plate. The two refractory plates have complementary abutting relative sliding surfaces located within the interior of the jacket of the container. A stationary tube member extends through the jacket and into the lining and has an inner end grasping the stationary refractory plate.