Metallurgical vessel with tapping device and method of controlled slag-free removal of molten metal from molten metal bath contained in this vessel

摘要

The present invention relates to a metallurgical vessel (1) having a tapping apparatus (5) for controlled slag-free withdrawal of liquid metal (3) from a molten metal bath in a lower vessel portion (2), wherein the tapping apparatus (5) includes a discharge duct (10), which is surrounded by refractory material, the discharge duct including first and second downwardly facing legs (11, 12) with respective tops at which said legs are connected to define a connecting region of said first and second legs (11, 12), the first leg (11) passes through a side wall of the vessel (1) and has an inlet opening (17) for liquid metal, the inlet opening including an upper edge (18), the second leg (12) has a lower outlet opening (20) for the liquid metal (3), which can be closed by a closure device (19). The discharge duct (10) includes an overflow edge (14) for the liquid metal (3) in the connecting region (13) of the first and second legs (11, 12). The overflow edge (13) is disposed at a height (h2) being greater than a height (H0) of the upper edge (18) of the inlet opening (17) of the discharge duct (10). The invention is characterized in that the first leg (11) of the discharge duct (10) passes through a refractory cladding of a side wall (15) of the lower vessel portion (2) and is integrated therewith. In the working position of the invented metallurgical vessel, the overflow edge (14) is arranged lower than an upper edge of the refractory cladding of the side wall (15) but at a maximum at a height (h3) defined by the maximum permissible bath level of the molten metal (3). A heating device, particularly of induction type, is provided for heating at least a portion of the discharge duct (10) or a molten metal (3) in the discharge duct (10). After tapping, said inlet opening (17) closes to thereby causing increase of molten metal (3) level in the vessel (1) up to the tapping height whereby the tapping is induced after closure of a ventilation valve (33) arranged in the connecting region (13) branch by opening the closure device (19).