Process for maintaining open a throttled discharge passage of a sliding

Abstract

Molten metal is discharged from a metallurgical vessel through a discharge passage of a sliding closure unit into a continuous casting mold. The molten metal level in the mold is established within a predetermined range by throttling the passage by a sliding plate of the sliding closure unit, during which throttling operation deposits gradually form in the sliding closure unit to restrict the size of the throttle passage and thereby reduce the molten metal level. The molten metal level is maintained within the predetermined range by the controlled opening movement of the sliding plate to compensate for restriction of the throttle passage by the formation of the deposits. Such deposits periodically are removed from the sliding closure unit by, in a single and continuous operation, moving the sliding plate from a compensating throttling position to which the sliding plate previously has been moved due to the formation of deposits, through an open unthrottled position of the sliding plate during which a surge of molten metal through the discharge passage flushes away the deposits, to a throttling position necessary to maintain the molten metal level within the predetermined range without the presence of deposits. The speed of this moving operation is controlled to ensure that the molten metal level remains within the predetermined range.