Metallurgical apparatus – Means for introducing fluent into vessel – e.g. – tuyere
Patent
1983-11-29
1985-09-03
Rosenberg, Peter D.
Metallurgical apparatus
Means for introducing fluent into vessel, e.g., tuyere
75 591, 266266, 266270, C22B 716
Patent
active
045390436
DESCRIPTION:
BRIEF SUMMARY
A first embodiment of the present invention relates to a molten metal refining nozzle which is mounted, for example, in the bottom of a molten metal refining furnace for blowing gas therethrough and its object is to increase the flow control range of the refining nozzle during the gas blowing and also to increase the service life of the nozzle itself.
It is well known in the art that for the purpose, for example, of refining, degassing or stirring molten metal, gas blowing refractory nozzles are mounted mainly in the bottom of a molten metal vessel and various kinds of gases are blown into the molten metal through the nozzles. Also, recently it has been made known to blow gas into a refining furnace, such as a converter, through its bottom by means of the gas blowing nozzles made of refractory material and the nozzles for this purpose have been proposed by the group of inventors, etc., in Japanese Patent Application No. 56-84321 and Japanese Utility Model Application No. 56-125950.
However, the later investigations of these proposed nozzles have shown that the following problems are encountered. holes therethrough, the melting loss of the nozzle refractory increases with decrease in the spacing between the holes. steel tube embedded in the refractory, the steel tubes will be crushed during the manufacture if the wall thickness is thin and the melting loss will be increased during the use if the wall thickness is large. part of the gas blowing refractory, the flow of the blown gas will be deteriorated and the melting loss will be increased if the distance between the upper and lower steel plates forming the pressure box is too small. adversely if the thickness of the metal cover enclosing the sides of the gas blowing refractory is not proper. proper, the penetration of the molten steel and slag will increase and also the damage due to thermal spalling will be increased.
The first embodiment of the invention is intended to solve the foregoing unsolved problems of the molten metal refining nozzles for gas blowing purposes and it provides a measure for overcoming each of these problems.
The subject matter of the first embodiment of the invention resides in a molten metal refining nozzle comprising a refractory having a plurality of holes extending from its working surface to its back, a metal cover enclosing the sides of the refractory, and a pressure box provided in the bottom of the refractory so as to communicate with the holes and define a gas reservoir space.
Another feature of the first embodiment of the invention is that the spacing between the plurality of holes in the refractory is selected not less than 3 mm and not greater than 150 mm.
Still another feature of the first embodiment of the invention is that each of the plurality of holes in the refractory is provided by a metal tube embedded in the refractory and the wall thickness of the metal tubes is selected as not less than 0.1 mm and not greater than 10 mm.
Still another feature of the first embodiment of the invention is that the metal cover comprises a steel plate having a thickness of not less than 0.1 mm and not greater than 5 mm.
Still another feature of the first embodiment of the invention is that the distance between the upper and lower metal plates defining the gas reservoir space of the pressure box is selected as not less than 2 mm and not greater than 50 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal view showing an example of a molten metal refining nozzle according to a first embodiment of the invention.
FIG. 2 is a plan view of the nozzle.
FIG. 3 is a graph showing a flow control characteristic of the nozzle according to the first embodiment of the invention.
FIG. 4 is a graph showing changes in the rate of melting loss of the nozzle.
FIG. 5 is a graph showing the relationship between the rate of melting loss of the nozzle and the tapping temperature.
FIG. 6 is a graph showing the bottom blowing pattern in the tests the data of which are shown in FIG. 4.
FIG. 7-1 is a longitudinal sectional view showing an examp
REFERENCES:
patent: 3330645 (1967-07-01), De Moustier
patent: 3971548 (1976-07-01), Folgero
patent: 4438907 (1984-03-01), Kimura
Hanmyo Masayuki
Hasegawa Teruyuki
Hiraga Noriyuki
Miyawaki Yoshiharu
Nimura Yoichi
Nippon Kokan Kabushiki Kaisha
Rosenberg Peter D.
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