Patent EA-003075-B1 (EA)
Title: Metallurgical vessel comprising a tapping device and method for the controlled, slag-free extraction of molten metal from said vessel
Inventor: FUCHS GERHARD
IPC: B22D41/14
Filed: 2000-03-31
Abstract: 1. A metallurgical vessel (1, 101) having a tapping apparatus (5, 105) for controlled slag-free withdrawal of liquid metal (3, 103) from a molten metal bath (3, 103) in the lower vessel portion (2, 102), wherein the tapping apparatus (5, 105) includes a discharge duct (10, 110) which is surrounded by refractory material and which has two downwardly facing legs (11, 12, 111, 112) which are connected at the top and of which the first (11, 111) passes through the vessel at an inlet opening (17, 117) with an upper edge (18) and the second (12, 112) has a lower outlet opening (20, 120) for the liquid metal (3, 103), which can be closed by a closure device (19, 119), and moreover an overflow edge (14, 114) for the liquid metal is defined within the closure duct in the connecting region (13, 113) of the two legs (11, 12, 111, 112) at a height (h2) greater than the height (h0) of the upper edge of the inlet opening of the discharge duct, characterised in that the first leg (11, 111) of the discharge duct (10, 110) passes through the refractory cladding of the vessel wall (15, 115) of the lower vessel portion (2) and is integrated into same, in the working position of the vessel the overflow edge (14, 114) is arranged lower than the upper edge of the refractory cladding of the vessel wall (15, 115) but at a maximum at a height (h3) defined by the maximum permissible bath level (h3) of the molten metal (3), and at least a part of the refractory material surrounding the discharge duct (10) or a molten metal (3) in the discharge duct is heatable by means of a heating device (24, 25, 144). 2. A metallurgical vessel according to claim 1 characterised in that arranged in the connecting region (13) of the two legs (11, 12) of the discharge duct (10) is at least one pipe connection (27, 28) which is lined with refractory material and which by means of a flange (29, 30) can be gas-tightly closed and/or can be connected to at least one external device. 3. A metallurgical vessel according to claim 2 characterised in that at least one of the two legs (11, 12) of the discharge duct (10) has a pipe connection (29, 30) which is aligned with the respective leg. 4. A metallurgical vessel according to claim 2 or claim 3 characterised in that the flange (30) is provided with a connecting pipe (31) to which a vacuum device (39) can be connected, as an external device, by way of a first valve (32). 5. A metallurgical vessel according to one of claims 2 to 4 characterised in that the flange (30) is provided with a connecting pipe (31) which can be communicated with the free atmosphere by way of a second ventilation valve (33). 6. A metallurgical vessel according to one of claims 1 to 5 characterised in that there is provided a device (40) for detecting and possibly controlling the height of the level of the bath (h4) in the connecting region (13) of the two legs (11, 12) of the discharge duct (10). 7. A metallurgical vessel according to claim 6 characterised in that provided in conjunction with a vacuum device (39) which can be set to a constant pressure is a level sensor which detects the height of the bath level (h4) in the connecting region (13) of the two legs (11, 12) of the discharge duct (10) and which supplies control signals to a regulating valve (38) which is disposed in a gas conduit communicating the connecting region (13) with the free atmosphere. 8. A metallurgical vessel according to one of claims 1 to 7 characterised in that at least one porous flushing or scavenging brick (36, 37) which can be connected to a pressurised gas source by way of a pressurised gas line opens in the proximity of the inlet opening (17) of the discharge duct for the introduction of a gas into the interior of the vessel (1) or the discharge pipe (10). 9. A metallurgical vessel according to claim 8 characterised in that the flushing or scavenging brick (36, 37) opens into the through-flow duct of the discharge duct (10) at the underside and/or at the top side of the first leg (11). 10. A metallurgical vessel according to one of claims 2 to 9 characterised in that in the working position of the vessel, the flange (29, 30) of the pipe connection is higher than the height (h3) defined by the maximum permissible level of the molten metal bath. 11. A metallurgical vessel according to one of claims 1 to 10 characterised in that in the working position of the vessel (1), the overflow edge (14) is higher than the level (h7) of the level of the molten metal bath, at which slag is drawn into the discharge pipe from the layer of slag (41) floating on the molten metal (13), said slag being drawn into the discharge pipe by intake eddies above the upper edge (18) of the inlet opening (17) of the discharge duct. 12. A metallurgical vessel according to one of claims 1 to 11 characterised in that in the working position of the vessel (1), the overflow edge (14) is lower than the level (h5) of the bottom (42) of a slag discharge opening (7) which is provided in the vessel wall (15). 13. A metallurgical vessel according to claim 12 characterised in that in the working position of the vessel (1), the overflow edge (14) is approximately at a height (h3) which is defined by the maximum permissible level (h3) of the molten metal bath (3). 14. A metallurgical vessel according to one of claims 1 to 13 characterised in that the first leg (11) of the discharge duct (10) passes through the refractory vessel wall (15), rising inclinedly as viewed from the interior of the furnace. 15. A metallurgical vessel according to one of claims 1 to 13 characterised in that the first leg (111) of the discharge duct (110) includes a horizontal first portion (111a) and a vertical second portion (111b) which is connected to the second leg (112) by way of the connecting region (113). 16. A metallurgical vessel according to one of claims 1 to 15 characterised in that the second leg (12) of the discharge duct (10) is arranged within a bay-like projection of the furnace vessel (1). 17. A metallurgical vessel according to one of claims 1 to 16 characterised in that a portion (23) of reduced through-flow cross-section, for restricting the through-flow, is provided in the second leg (12) of the discharge duct (10). 18. A metallurgical vessel according to claim 17 characterised in that the portion (23) of reduced through-flow cross-section is arranged just in front of the outlet opening (20) of the discharge duct (10). 19. A metallurgical vessel according to claim 17 or claim 18 characterised in that the portion (23) of reduced through-flow cross-section is replaceable. 20. A metallurgical vessel according to one of claims 1 to 19 characterised in that the through-flow cross-section of the discharge duct (10), at least in the region of the inlet opening (17) of the first leg (11), is of a rectangular configuration or an oval configuration of greater width than its height. 21. A metallurgical vessel according to one of claims 1 to 20 characterised in that the ratio between the cross-section of the discharge duct outlet opening (17, 117) and the cross-section of the portion (23, 123) limiting the through-flow is about 4:1. 22. A metallurgical vessel according to one of claims 2 to 21 characterised in that the heating device can be connected to the pipe connection (27). 23. A metallurgical vessel according to one of claims 2 to 22 characterised in that a container with granular refractory material can be connected by way of a metering device to a pipe connection (28) which is aligned with the second leg (12) of the discharge duct (10). 24. A metallurgical vessel according to one of claims 1 to 23 characterised in that the heating device has at least one induction coil (24, 25) which surrounds the first and/or second leg of the discharge duct (10). 25. A metallurgical vessel according to one of claims 1 to 24 characterised in that the closure device (19) of the outlet opening (20) of the discharge duct (10) includes a closure plate member (21) which is movable repeatedly by means of a drive from a closing position of bearing against the edge of the outlet opening (20) into an open position of opening the outlet opening (20), and from the open position into the closing position. 26. A metallurgical vessel according to one of claims 1 to 25 characterised in that the inlet opening (17, 117) of the discharge pipe is arranged adjacent to the vessel bottom (8). 27. A metallurgical vessel according to one of claims 1 to 26 characterised in that the vessel (101) is adapted to be tiltable in the direction of the tapping apparatus (110). 28. A metallurgical vessel according to one of claims 1 to 27 characterised in that the height (h2) of the overflow edge (14, 114) is higher and preferably only slightly higher than the height of the surface of the bed (h7) of molten metal (3, 103) present in the vessel (1), in which intake eddies cause slag (41, 141) floating on the molten metal (3, 103) to be drawn into the discharge duct (10, 110) over the overflow edge (18, 118) of the inlet opening (17, 117) of the discharge duct. 29. A process for the controlled slag-free withdrawal of liquid metal from a molten metal bath in a vessel, on the basis of the principle of a liquid siphon, by means of an apparatus according to one of claims 1 to 29, wherein after a tapping operation the outlet opening of the discharge duct is closed, possibly the level of the molten bath in the vessel is increased to a tapping height, in particular by melting metal into the bath, and the tapping operation is initiated after closure of a ventilation valve provided in a branch from the connecting region of the two legs, by opening of the closure device of the second leg and drawing off a residual amount retained in the second leg from the preceding tapping operation and/or an overflow amount of the molten metal, which has previously been supplied by flowing over the overflow edge of the connecting region of the two legs, whereby further molten metal