Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1996-07-01
1998-09-08
Kastler, Scott
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
266217, 266265, C21C 700
Patent
active
058039481
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a process for introducing gases into a metal melt contained in metallurgical vessels via ducts arranged in the refractory lining of the vessel, and a device for carrying out this purpose.
2. Description of Prior Art
Such a process and device are generally known from "Patent Abstracts of Japan" (Vol. 15, No. 76, C-809, Feb. 21, 1991) by JA-A 02 301 525.
In general, various gas flushing systems are known in steel mills for introducing gases into metallurgical melts which serve primarily for homogenizing and cleaning the melts. In general, the gas used is argon or nitrogen. Another field of use is the bottom-blown process with oxygen in metal treatment vessels such as furnace ladles, desulfurizing pans, etc. In this connection the gases are blown into the metal bath through the bottom of the vessel and the lining of the vessel walls.
The gas is ordinarily conducted through gas flushing stones, whether permeable or dense. In the case of the permeable flushing stones, the gas flows directly through the stone structure which has a capillaries system on the order of magnitude of 10 to 20.
The capillary or duct system of gas flushing stones has great resistance to flow. Upon the discharge of gas from the known gas flushing stones, particularly with a high rate of gas flow, bubbles of large size are formed as a result of the mixing together of small bubbles.
Furthermore, the existing embodiments of permeable gas flushing stones show low intensity upon the mixing of the metal melt and a low factor of utilization of the energy of flow.
Upon the use of slit ducts, longitudinal eddy structures arise during the flow of the gases through the ducts, with the result that the jet of gas is impeded and does not have sufficient intensity upon the mixing of the metal melt. This has the result, even when several ducts are used alongside each other, that the jets separate into a number of thin unstable jets, which in turn reduces the mixing of the melt.
SUMMARY OF THE INVENTION
The object of the present invention is to avoid the above-mentioned disadvantages and to provide a process and an apparatus corresponding to it in which, with only slight losses of energy, a deeper penetration of the jet of gas into the liquid melt and better mixing with the liquid melt are made possible, and in which the time for the homogenizing and cleaning of the melt is reduced.
In the process proposed, the gas, before being introduced into the metal melt, is fed into a gas distributor in which acoustic generators for the exciting of oscillations of the gas are provided. Depending on the properties of the flushing gas in the gas line and the development of the acoustic generators, the behavior of the gas oscillations and their frequency can be varied in regions. Upon the exciting of the gas by the acoustic generators, shock waves are produced which propagate themselves through the gas distributor and enter the ducts.
The oscillations of the gas jet, the interaction of the flows, and the formation of the shock waves within the acoustic generator are controlled, as a function of the properties of the flushing process and the environment into which the gas enters, in a frequency and amplitude which can be predetermined.
The excited gas is fed to the melt by ducts which are combined in a bundle. The thin jets flowing out of the bundle of ducts attract each other behind the mouth of the nozzle and thus stabilize the discharging total gas jet. This stable gas system produces an eddy system of high intensity in the metal melt and exerts a high positive influence on the mixing process of the metal melt in the metallurgical vessel. The eddy system here protects the metal melt not only kinetically but also with respect to the oscillation. The interaction between the flow of gas and the metal melt has a jet-like character. An eddy system with longitudinal and transverse waves is produced in the metallurgical vessel.
The ducts of the gas flushing stone have a triangular cross-
REFERENCES:
patent: 4392636 (1983-07-01), Clumpner
patent: 4438907 (1984-03-01), Kimura et al.
patent: 5312092 (1994-05-01), Decker et al.
Meyer Ulrich
Scholer Horst-Dieter
Sizov Anatoly
Kastler Scott
Mannesmann Aktiengesellschaft
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