Abstract: A method of preventing slag from escaping when emptying a pouring vessel with a bottom outlet. The vessel contains steel and slag. During the end phase of the emptying of the pouring vessel, between the discharge opening and the interior space of the vessel a barrier of liquid steel is built up by passing the steel through a system of communicating flow paths surrounding the discharge opening. Thus the steel is caused with the remainder of its content in the vessel prior to the discharge of this remainder from the vessel, due to its greater specific weight automatically to prevent the lighter slag from entering the system and to reach the discharge opening. The vessel for practicing the above mentioned method has its discharge opening surrounded by a groove-shaped recess, the lowermost portion of which is located below the level of the upper edge of the discharge opening. A wall annularly extends from above into the recess without contacting the lowermost portion of the recess.