Dispensing – Processes of dispensing – Molten metal
Patent
1988-10-20
1990-03-20
Kastler, S.
Dispensing
Processes of dispensing
Molten metal
222594, 222602, B72D 1110
Patent
active
049094211
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an installation for casting liquid metal comprising a metallurgical receptacle adapted to contain liquid metal, provided with a casting orifice and comprising below this orifice a principal device for closing and opening said orifice.
The invention relates also to the process for using this installation.
It is known that all metallurgical receptacles such as a casting ladle or a tundish for continuous casting, principally for slabs or blooms, comprise a device for closing the casting orifice to permit the closing of this latter before and during the beginning of the casting of the liquid metal in this receptacle, then the opening of this orifice to permit the casting of liquid metal into a second metallurgical receptacle, for example into a continuous casting mold.
Such an apparatus should also permit the partial or total closing of this orifice if it is necessary to limit the flow rate or interrupt the flow of the liquid metal.
The most common closure devices are stopper rods provided with a known refractory cladding requiring heating before the casting of the metal to avoid any risk of solidification of the latter in contact with its surface. The stopper rods are moreover heavy and difficult to manipulate.
Closure devices used at present are sliding nozzles. These are quite satisfactory as to a closing operation before and during casting and at the end of the latter. On the other hand, it can happen that in spite of care taken to prepare the casting receptacle before casting, there will form in the casting orifice a plug of various debris, slag and/or solidified metal preventing the casting of the liquid metal or greatly limiting it.
Such an incident can seriously upset the use of the liquid metal casting room, by retarding the meal casting for the time necessary to clean the obstructed casting orifice, or by prolonging the length of casting as for example in the case of an installation for the continuous casting of liquid metal on several lines, if the casting director decides to avoid use of the obstructed line and use only the other available lines.
If all the lines are obstructed, it can happen that the metal must be cast into holding molds permitting the solidification of ingots which will then be remelted.
Non-opening therefore always generates supplemental costs by loss of production.
The solution consists generally in trying to burn with oxygen the incandescent magma forming the plug which obstructs the casting orifice. To do that, one introduces into this orifice through the lower part of the metallurgical receptacle, a metallic tube through which is supplied a jet of oxygen. It forms on contact with the magma a flame whose heat will melt the latter. This operation is always very delicate. Thus, it frequently happens that in melting the magma the casting orifice and/or the sliding device are damaged. Moreover, this operation is dangerous for the personnel who perform it.
Such a clearing operation is rendered even more delicate when one uses beneath the metallurgical receptacle a casting tube adapted to prevent contact between the liquid metal and the air and the risk of oxidation, while limiting splash. It has been attempted to develop casting tubes provided substantially along their axis with a metallic nozzle by which oxygen can be supplied if the liquid metal does not flow through the casting orifice upon opening the slide device. But cleaning from below the metallic receptacle has never been entirely satisfactory.
Another solution is also proposed in U.S. Pat. No. 4,667,858 to avoid plugging the casting orifice of a metallic receptacle provided with a closure device of the type of a slide nozzle. This solution consists in placing sand in the casting orifice above the slide. However, when the slide is opened, the sand flows and pollutes the metal in the lower receptacle.
It is also known in the steel art to use stopper rods for metallurgical receptacles constituted by a hollow central metallic tube covered with a refractory protection. These stopper rods are a
REFERENCES:
patent: 3200457 (1965-08-01), Wagstaff et al.
patent: 4508247 (1985-04-01), Mills et al.
patent: 4667858 (1987-05-01), Nishio et al.
patent: 4791978 (1988-12-01), Fishler
Daussan Andre P.
Daussan Gerard
Daussan Jean C.
Daussan et Compagnie
Kastler S.
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