GB2145740A - Immersion tube for vacuum- refining molten steel - Google Patents
Immersion tube for vacuum- refining molten steel Download PDFInfo
- Publication number
- GB2145740A GB2145740A GB08421294A GB8421294A GB2145740A GB 2145740 A GB2145740 A GB 2145740A GB 08421294 A GB08421294 A GB 08421294A GB 8421294 A GB8421294 A GB 8421294A GB 2145740 A GB2145740 A GB 2145740A
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- United Kingdom
- Prior art keywords
- bricks
- cylinder
- molten steel
- immersion tube
- inner bore
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Furnace Housings, Linings, Walls, And Ceilings (AREA)
Abstract
The immersion tube has an inner bore for passing molten steel therethrough and comprises: a steel cylinder (1); a plurality of high- alumina fired radial bricks (2); a plurality of magnesia-chrome fired radial bricks (9) of which the ratio of length of two adjacent sides of a rectangular face which forms the inner bore (9b) is within the range of from 0.8 to 1.2; and a high- alumina castable layer (4) lined over the entire outer surface of the cylinder. <IMAGE>
Description
SPECIFICATION
Immersion tube for vacuum-refining molten steel
The present invention relates to, in the RHtype vacuum-refining process of molten steel, a pair of immersion tubes for vacuum-refining molten steel, which are to be vertically connected to a bottom wall of a vacuum tank for refining molten steel equipped with a vacuum pump, so as to project downwardly from the bottom wall, for circulating molten steel received in a ladle located below the vacuum tank through the pair of immersion tubes between the vacuum tank and the ladle.
As one of the vacuum-refining processes of molten steel, the RH-type vacuum-refining process is known, which comprises immersing a pair of immersion tubes vertically connected to a bottom wall of a vacuum tank for refining molten steel equipped with a vacuum pump so as to project downwardly from the bottom wall into molten steel received in a ladle located below the vacuum tank, blowing an inert gas from one of the pair of immersion tubes while reducing the pressure in the vacuum tank by means of the vacuum pump to suck up molten steel received in the ladle through the one of the immersion tubes into the vacuum tank, and returning molten steel sucked up into the vacuum tank through the other one of the immersion tubes into the ladle to cause molten steel received in the ladle to circulate between the ladle and the vacuum tank, thereby degassing, in the vacuum tank, molten steel received in the ladle to refine molten steel.
In the above-mentioned RH-type vacuumrefining process, each of the pair of immersion tubes vertically connected to the bottom wall of the vacuum tank so as to project downwardly therefrom has an inner bore made of a refractory material for passing molten steel therethrough, and each of the pair of immersion tubes has a length sufficient to allow at least the lower end portion thereof to be immersed into molten steel received in a ladle located below the vacuum tank. Such an immersion tube has a length of from about 700 to about 1,000 mm, the inner bore of the immersion tube has a diameter of from about 300 to about 700 mm, and from about 4 to about 1 6 inert gas blowing through-holes are provided in the lower portion of the inner bore.
The inner bore made of the refractory material of the immersion tube is susceptible to a serious erosion because molten steel vigorously flows therethrough. The portion of the inner bore, which is in contact with molten steel flow largely disturbed by the blowing of inert gas, is particularly seriously eroded under the effect of a large mechanical friction.
To avoid this inconvenience, the upper portion of-the inner bore of the immersion tube, which is above the portion having the inert gas blowing through-holes, is usually formed with the use of magnesia-chrome fired bricks excellent in erosion resistance against molten steel.
Fig. 1 is a schematic longitudinal sectional view illustrating a conventional immersion tube used for the RH-type vacuum-refining process of molten steel. As shown in Fig. 1, the conventional immersion tube comprises: a steel cylinder 1; a plurality of high-alumina fired radial bricks 2 piled up in a horizontal annular row, in contact with the inner surface of the cylinder 1, over the entire circumference of the lower portion of the inner surface of the cylinder 1, so as to form, in the cylinder 1, the lower portion of an inner bore for passing molten steel therethrough; a plurality of magnesia-chrome fired radial bricks 3 piled up in a plurality of horizontal annular rows which are arranged one on the other, in contact with the inner surface of the cylinder 1, over the entire circumference of the remaining portion of the inner surface of the cylinder 1, on the horizontal annular row of the plurality of high-alumina bricks 2, so as to form the upper portion of the inner bore in the cylinder 1, in cooperation with the plurality of high-alumina bricks 2; and a highalumina castable layer 4 lined over the entire outer surface of the cylinder 1 and over the entire lower surface of the horizontal annular row of the plurality of high-alumina bricks 2.
A steel flange 5 for connecting the immersion tube to the bottom wall of the vacuum tank is fixed by welding for example, to the outer periphery of the upper end of the cylinder 1. An inwardly bent rim 6 for hooking the high-alumina fired radial bricks 2 is provided at the lower end of the cylinder 1.
The horizontal side of a rectangular face which is in contact with the inner surface of the cylinder 1, of each of the high-alumina fired radial bricks 2, is longer than the horizontal side of a rectangular face which forms the inner bore of the immersion tube. The vertical side of the rectangular face which is in contact with the inner surface of the cylinder 1 and the vertical side of the rectangular face which forms the inner bore of the immersion tube, of each of the high-alumina bricks 2, are longer than the respective horizontal sides. An offset portion 2a for being hooked on the rim 6 of the cylinder 1 is formed at the lower portion of the rectangular face which is in contact with the inner surface of the cylinder
1, of each of the high-alumina bricks 2.The high-alumina bricks 2 are piled up in a horizontal annular row, in contact with the inner surface of the cylinder 1 through a joint of a high-alumina castable, over the entire circumference of the lower portion of the inner surface of the cylinder 1, with the offset portions 2a of the high-alumina bricks 2 hooked on the rim 6 of the cylinder 1.
As shown in Fig. 2(a), the horizontal side of a rectangular face 3a which is in contact with the inner surface of the cylinder 1. of each of the magnesia-chrome fired radial bricks 3, is longer than the horizontal side of a rectangular face 3b which forms the inner bore of the immersion tube. The vertical side of the rectangular face 3a which is in contact with the inner surface of the cylinder 1 and the vertical side of the rectangular face 3b which forms the inner bore, of each of the magnesiachrome bricks 3, are longer than the respective horizontal sides.The magnesia-chrome bricks 3 are piled up in a plurality of horizon tal annular rows which are arranged one on the other, in contact with the inner surface of the cylinder 1 through a joint of a highalumina castable, over the entire circumference of the remaining portion of the inner surface of the cylinder 1, on the horizontal annular row of the plurality of high-alumina bricks 2. Among the plurality of magnesiachrome bricks 3 piled up in the plurality of horizontal annular rows, at least one of those arranged in the lowermost horizontal annular row has an inert gas blowing through-hole 7 as shown in Fig. 2(b), which passes through from the face 3a which is in contact with the inner surface of the cylinder 1 to the face 3b which forms the inner bore of the immersion tube.A steel pipe 8 is connected to the inert gas blowing through-hole 7, which steel pipe 8 passes through the cylinder 1. Inert gas such as argon gas is blown through the steel pipe 8 and the inert gas blowing through-hole 7 into the inner bore of the immersion tube.
The magnesia-chrome fired radial brick 3 of the conventional immersion tube has, for example, a length of 80 mm of the horizontal side of the rectangular face 3a which is in contact with the inner surface of the cylinder 1, a length of 70 mm of the horizontal side of the rectangular face 3b which forms the inner bore, a length of 230 mm of the vertical side of each of the face 3a and the face 3b, and a length of 1 20 mm of the distance between the face 3a and the face 3b. In the conventional immersion tube, for example, two horizontal annular rows each comprising 24 piledup magnesia-chrome bricks 3 having the above-mentioned size are arranged one on the other on the horizontal annular row of the high-alumina bricks 2.
The high-alumina castable layer 4 is lined over the entire outer surface of the cylinder 1 and over the entire lower surface of the horizontal annular row of the plurality of highalumina bricks 2 by casting for example.
However, the above-mentioned conventional immersion tube has the following drawbacks. The magnesia-chrome fired radial bricks 3 which form the upper portion of the inner bore of the immersion tube, while being excellent in erosion resistance against molten steel, are inferior in thermal spalling resistance because of the high thermal expansion. Therefore, when immersing the immersion tube into molten steel in the ladle or when taking it up from molten steel in the ladle, a sudden thermal variation applied to the immersion tube causes thermal spalling in the magnesiachrome fired radial bricks 3 and thus largely reduces the thickness of the magnesia-chrome bricks 3. This makes it impossible to use the immersion tube after only a limited number of vacuum-refining cycles of molten steel.
Under such circumstances, there is a strong demand for development of an immersion tube for vacuum-refining molten steel, which.
when vacuum-refining molten steel by the RHtype vacuum-refining process, is capable of withstanding the use for more cycles of vacuum-refining, but an immersion tube for vacuum-refining molten steel provided with such a property is not as yet proposed.
An object of the present invention is therefore to provide an immersion tube for vacuum-refining molten steel, which, when vacuum-refining molten steel by the RH-type vacuum-refining process, is capable of withstanding the use for more cycles of vacuumrefining.
A principal object of the present invention is to provide an immersion tube for vacuumrefining molten steel, in which, when vacuumrefining molten steel by the RH-type vacuumrefining process, thermal spalling resistance of a plurality of magnesia-chrome fired radial bricks which form the upper portion of an inner bore of the immersion tube for passing molten steel therethrough is improved.
In accordance with one of the features of the present invention, there is provided a pair of immersion tubes for vacuum-refining molten steel, which are to be vertically connected to a bottom wall of a vacuum tank for refining molten steel equipped with a vacuum pump so as to project downwardly from said bottom wall, each of said pair of immersion tubes having an inner bore made of a refractory material for passing molten steel therethrough each of said pair of immersion tubes having a length sufficient to allow at least the lower end portion thereof to be immersed into molten steel received in a ladle located below said vacuum tank;
said immersion tube comprising: :
a steel cylinder;
a plurality of high-alumina fired radial bricks piled up in a horizontal annular row, in contact with the inner surface of said cylinder, over the entire circumfference of the lower portion of the inner surface of said cylinder, so as to form the lower portion of said inner bore in said cylinder, the horizontal side of a rectangular face which is in contact with the inner surface of said cylinder, of each of said plurality of high-alumina bricks, being longer than the horizontal side of a rectangular face which forms said inner bore;;
a plurality of magnesia-chrome fired radial bricks piled up in a plurality of horizontal annular rows which are arranged one on the other, in contact with the inner surface of said cylinder, over the entire circumference of the remaining portion of the inner surface of said cylinder, on said horizontal annular row of said plurality of high-alumina bricks, so as to form the upper portion of said inner bore in said cylinder in cooperation with said plurality of high-alumina bricks, the horizontal side of a rectangular face which is in contact with the inner surface of said cylinder, of each of said plurality of magnesia-chrome bricks, being longer than the horizontal side of a rectangular face which forms said inner bore, at least one of said plurality of magnesia-chrome bricks and the portion of said cylinder corresponding thereto having an inert gas blowing through-hole; and
a high-alumina castable layer lined over the entire outer surface of said cylinder and over the entire lower surface of said horizontal annular row of said plurality of high-alumina bricks;
said immersion tube being characterized in that:
the ratio of length of two adjacent sides of said rectangular face which forms said inner bore, of each of said plurality of magnesiachrome fired radial bricks is within the range of from 0.8 to 1.2.
Fig. 1 is a schematic longitudinal sectional view illustrating a conventional immersion tube used for the RH-type vacuum-refining process of molten steel;
Fig. 2(a) is a perspective view illustrating a magnesia-chrome fired radial brick which forms the upper portion of an inner bore for passing molten steel therethrough, of the conventional immersion tube as shown in Fig. 1;
Fig. 2(b) is a perspective view illustrating a magnesia-chrome fired radial brick provided with an inert gas blowing through-hole, which forms the upper portion of the inner bore for passing molten steel therethrough, of the conventional immersion tube as shown in Fig. 1;
Fig. 3 is a schematic longitudinal sectional view illustrating an embodiment of the immersion tube of the present invention used for the
RH-type vacuum-refining process of molten steel;;
Fig. 4(a) is a perspective view illustrating a magnesia-chrome fired radial brick which forms the upper portion of an inner bore for passing molten steel therethrough, of the immersion tube of the present invention as shown in Fig. 3; and
Fig. 4(b) is a perspective view illustrating a magnesia-chrome fired radial brick provided with an inert gas blowing through-hole, which forms the upper portion of the inner bore for passing molten steel therethrough, of the immersion tube of the present invention as shown in Fig. 3.
From the above-mentioned point of view, we carried out extensive studies to develop an immersion tube for vacuum-refining molten steel, which, when vacuum-refining molten steel by the RH-type vacuum-refining process, is capable of withstanding the use for more cycles of vacuumrefining with an improved thermal spalling resistance of a plurality of magnesia-chrome fired radial bricks which form the upper portion of an inner bore of the immersion tube for passing molten steel therethrough.
As a result, we found that it is possible to obtain an immersion tube for vacuum-refining molten steel, which, when vacuum-refining molten steel by the RH-type vacuum-refining process, is capable of withstanding the use for more cycles of vacuum-refining with an improved thermal spalling resistance of a plurality of magnesia-chrome fired radial bricks, by limiting the ratio of length of two adjacent sides of the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesia-chrome bricks, within the range of from 0.8 to 1.2.
The reason for limiting the ratio of length within the range of from 0.8 to 1.2 of two adjacent sides of the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesia-chrome fired radial bricks is as follows. The distribution of thermal stress produced in each of the plurality of magnesia-chrome bricks by a sudden thermal variation applied to the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesia-chrome bricks when immersing the immersion tube into molten steel in the ladle or when taking it up from molten steel in the ladle, becomes more uniform according as the shape of the above-mentioned rectangular face which forms the inner bore of the immersion tube is closer to a square.Thereffore, if the shape of the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesia-chrome bricks is substantially square, then the above-mentioned distribution of thermal stress becomes uniform, and a serious thermal stress never occurs locally in the brick, thus allowing to improve thermal spalling resistance of the brick.
On the other hand, if the ratio of length of two adjacent sides of the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesiachrome bricks, is under 0.8 or over 1.2, a large thermal stress is locally caused in the brick when a sudden thermal variation is applied to the rectangular face, thus leading to a lower thermal spalling resistance.
Therefore, the ratio of length of two adjacent sides of the rectangular face which forms the inner bore of the immersion tube, of each of the plurality of magnesia-chrome bricks should be limited within the range of from 0.8 to 1.2 in order to improve thermal spalling resistance of the brick.
Fig. 3 is a schematic longitudinal sectional view illustrating an embodiment of the immersion tube of the present invention used for the
RH-type vacuum-refining process of molten steel. As shown in Fig. 3, the immersion tube of the present invention comprises: a steel cylinder 1; a plurality of high-alumina fired radial bricks 2 piled up in a horizontal annular row, in contact with the inner surface of the cylinder 1, over the entire circumference of the lower portion of the inner surface of the cylinder 1, so as to form, in the cylinder 1, the lower portion of an inner bore for passing molten steel therethrough; a plurality of magnesia-chrome fired radial bricks 9 piled up in a plurality of horizontal annular rows which are arranged one on the other, in contact with the inner surface of the cylinder 1, over the entire circumference of the remaining portion of the inner surface of the cylinder 1, on the horizontal annular row of the plurality of highalumina bricks 2, so as to form the upper portion of the inner bore in the cylinder 1, in cooperation with the plurality of high-alumina bricks 2; and a high-alumina castable layer 4 lined over the entire outer surface of the cylinder I and over the entire lower surface of the horizontal annular row of the plurality of high-alumina bricks 2.
A steel flange 5 for connecting the immersion tube to the bottom wall of the vacuum tank is fixed by welding for example, to the outer periphery of the upper end of the cylinder 1. An inwardly bent rim 6 for hooking the high-alumina fired radial bricks 2 is provided at the lower end of the cylinder 1.
The horizontal side of a rectangular face which is in contact with the inner surface of the cylinder 1, of each of the high-alumina fired radial bricks 2, is longer than the horizontal side of a rectangular face which forms the inner bore of the immersion tube. The vertical side of the rectangular face which is in contact with the inner surface of the cylinder 1 and the vertical side of the rectangular face which forms the inner bore of the immersion tube, of each of the high-alumina bricks 2, are longer than the respective horizontal sides. An offset portion 2a for being hooked on the rim 6 of the cylinder 1 is formed at the lower portion of the rectangular face which is in contact with the inner surface of the cylinder 1, of each of the high-alumina bricks 2.The high-alumina bricks 2 are piled up in a horizontal annular row, in contact with the inner surface of the cylinder 1 through a joint of a high-alumina castable, over the entire circumference of the lower portion of the inner surface of the cylinder 1, with the offset portions 2a of the high-alumina bricks 2 hooked on the rim 6 of the cylinder 1.
As shown in Fig. 4(a), the horizontal side of a rectangular face 9a which is in contact with the inner surface of the cylinder 1, of each of the magnesia-chrome fired radial bricks 9, is longer than the horizontal side of a rectangular face 9b which forms the inner bore of the immersion tube. With a view to improving thermal spalling resistance of the magnesiachrome bricks 9 against a sudden thermal variation applied to the rectangular face 9b, the ratio of length of two adjacent sides of the rectangular face 9b is limited within the range of from 0.8 to 1.2.The magnesia-chrome bricks 9 are piled up in a plurality of horizontal annular rows which are arranged one on the other, in contact with the inner surface of the cylinder 1 through a joint of a highalumina castable, over the entire circumference of the remaining portion of the inner surface of the cylinder 1, on the horizontal annular row of the plurality of high-alumina bricks 2.
It is the widely applied practice to use an immersion tube having a length of from 700 to 1 ,000 mm, with an inner bore for passing molten steel therethrough having a diameter of from 300 to 700 mm and a length of the upper portion of the inner bore formed by a plurality of magnesia-chrome fired radial bricks of from 400 to 600 mm. In order to form the upper portion of the inner bore of such an immersion tube, it is desirable to use from 60 to 1 80 magnesia-chrome fired radial bricks in which two adjacent sides of the rectangular face which forms the inner bore of the immersion tube have a ratio of length within the range of from 0.8 to 1.2. The reason is as follows.A joint of a magnesia mortar in thickness of from about 1 to about 2 mm is applied between the magnesiachrome fired radial bricks 9 and between these bricks and the high-alumina fired radial bricks 2. When the number of the magnesiachrome bricks 9 is under 60, the amount of the joint is smaller. It is therefore impossible for such a small amount of the joint to sufficiently absorb the expansion of the bricks 9 caused by heating by molten steel during refining molten steel, thus causing a considerable thermal stress in these bricks, and hence thermal spalling in the bricks 9. On the other hand, when the number of the magnesiachrome bricks 9 is over 180, there are too many amount of the joint to disregard erosion of the joint, and this may cause these bricks 9 to fall down.
Among the plurality of magnesia-chrome fired radial bricks 9 piled up in the plurality of horizontal annular rows, at least one of those arranged in the lowermost horizontal annular row has an inert gas blowing through-hole 7 as shown in Fig. 4(b), which passes through from the face 9a which is in contact with the inner surface of the cylinder 1 to the fare 9iv which forms the inner bore of the immersion tube. A steel pipe 8 is connected to the inert gas blowing through-hole 7, which steel pipe 8 passes through the cylinder 1. Inert gas such as argon gas is blown through the steel pipe 8 and the inert gas blowing through-hole 7 into the inner bore of the immersion tube.
The high-alumina castable layer 4 is lined over the entire outer surface of the cylinder 1 and over the entire lower surface of the horizontal annular row of the plurality of highalumina fired radial bricks 2 by casting for example.
Now, the immersion tube for vacuum-refining molten steel of tHe present invention is described in more detail by means of an example.
Example
The RH-type vacuum-refining of molten steel was carried out using the pair of immersion tubes for vacuum-refining molten steel of the present invention, which have been described with reference to Fig. 3, each having a length of 770 mm and an inner bore diameter of 540 mm, to research the service life of the immersion tube. For comparison purposes, the RH-type vacuum-refining of molten steel was carried out using the pair of conventional immersion tubes for vacuum-refining molten steel, which have been described with reference to Fig. 1, each having a length of 790 mm and an inner bore diameter of 540 mm, to research the service life of the immersion tube.
As the magnesia-chrome fired radial bricks 9 which form the upper portion of the inner bore of the immersion tube of the present invention, the bricks of the dimensions and in the number as shown under 1 below, which have been described with reference to Fig.
4(a) and Fig. 4(b) were used. As the magnesia-chrome fired radial bricks 3 which form the upper portion of the inner bore of the conventional immersion tube, on the other hand, the bricks of the dimensions and in the number as shown under 2 below, which have been described with reference to Fig. 2(a) and
Fig. 2(b) were used.
1. Magnesia-chrome fired radial brick 9 used for the immersion tube of the present invention:
(1) Length of the horizontal side of the face 9a which is in contact with the inner surface of the steel cylinder 1: 1 39 mm,
(2) Length of the horizontal side of the face 9b which forms the inner bore of the immersion tube: 87 mm,
(3) Length of the vertical side of each of the face 9a and the face 9b: 87 mm,
(4) The ratio of length of the vertical side to the horizontal side of the face 9b which forms the inner bore of the immersion tube: 1.0,
(5) Distance between the face 9a and the face 9b: 1 20 mm,
(6) Number of magnesia-chrome bricks 9: 95 bricks piled up in five horizontal annular rows each comprising 1 9 bricks, and
(7) Number of magnesia-chrome bricks 9 each provided with the inert gas blowing through-hole 7: 10.
2. Magnesia-chrome fired radial brick 3 used for the conventional immersion tube:
(1) Length of the horizontal side of the face 3a which is in contact with the inner surface of the steel cylinder 1: 1 10 mm,
(2) Length of the horizontal side of the face 3b which forms the inner bore of the immersion tube: 70 mm,
(3) Length of the vertical side of each of the face 3a and the face 3b: 230 mm,
(4) The ratio of length of the vertical side to the horizontal side of the face 3b which forms the inner bore of the immersion tube: 3.3,
(5) Distance between the face 3a and the face 3b: 1 20 mm,
(6) Number of magnesia-chrome bricks 3: 48 bricks piled up in two horizontal annular rows each comprising 24 bricks, and
(7) number of magnesia-chrome bricks 3 each provided with the inert gas blowing through-hole 7: 10.
Vacuum-refining was carried out for molten steel received in a 250-ton ladle under the following conditions:
(1) pressure in the vacuum tank: 0.2 Torr,
(2) Volume of blown argon gas: 1,000
N1 /minute
(3) Flow rate of molten steel: 80 tons/minute
(4) Amount of molten steel refined per cycle: 250 tons, and
(5) Refining period of time per cycle: 20 minutes.
Argon gas was first blown through the inert gas blowing through-holes 7 of one of the pair of immersion tubes for half the total number of refining cycles, and then through the inert gas blowing through-holes 7 of the other one of the pair of immersion tubes for the remaining cycles.
As a result, the immersion tube of the present invention withstood from 1 80 to 200 cycles of refining since thermal spalling did not occur in the magnesiachrome bricks 9 and there was only a small decrease in the thickness of the bricks 9. The conventional immersion tube became in contrast unusable after refining of only 1 20 cycles since thermal spalling occurred considerably in the magnesia-chrome bricks 3 and there was a large decrease in the thickness of the bricks 3.
According to the present invention, as described above in detail, it is possible to obtain an immersion tube for vacuum-refining molten steel, in which, when vacuum-refining molten steel by the RH-type vacuum-refining process, thermal spalling resistance of a plurality of magnesia-chrome fired radial bricks which form the upper portion of the inner bore of the immersion tube for passing molten steel therethrough are remarkably improved, and the service life of the immersion tube is extended to from 1.5 to 1.7 time as long as compared with the conventional immersion tube for vacuum-refining molten steel, thus providing industrially useful effects.
Claims (3)
1. A pair of immersion tubes for vacuumrefining molten steel, which are to be vertically connected to a bottom wall of a vacuum tank for refining molten steel equipped with a vacuum pump so as to project downwardly from said bottom wall, each of said pair of immersion tubes having an inner bore made of a refractory material for passing molten steel therethrough, each of said pair of immersion tubes having a length sufficient to allow at least the lower end portion thereof to be immersed into molten steel received in a ladle located below said vacuum tank;
said immersion tube comprising::
a steel cylinder;
a plurality of high-alumina fired radial bricks piled up in a horizontal annular row, in contact with the inner surface of said cylinder, over the entire circumference of the lower portion of the inner surface of said cylinder, so as to form the lower portion of said inner bore in said cylinder, the horizontal side of a rectangular face which is in contact with the inner surface of said cylinder, of each of said plurality of high-alumina bricks, being longer than the horizontal side- of a rectangular face which forms said inner bore;;
a plurality of magnesia-chrome fired radial bricks piled up in a plurality of horizontal annular rows which are arranged one on the other, in contact with the inner surface of said cylinder, over the entire circumference of the remaining portion of the inner surface of said cylinder, on said horizontal annular row of said plurality of high-alumina bricks, so as to form the upper portion of said inner bore in said cylinder in cooperation with said plurality of high-alumina bricks, the horizontal side of a rectangular face which is in contact with the inner surface of said cylinder, of each of said plurality of magnesia-chrome bricks, being longer than the horizontal side of a rectangular face which forms said inner bore, at least one of said plurality of magnesia-chrome bricks and the portion of said cylinder corresponding thereto having an inert gas blowing through-hole; and
a high-alumina castable layer lined over the entire outer surface of said cylinder and over the entire lower surface of said horizontal annular row of said plurality of high-alumina bricks;
said immersion tube being characterized in that:
the ratio of length of two adjacent sides of said rectangular face (9b) which forms said inner bore, of each of said plurality of magnesia-chrome fired radial bricks (9) is within the range of from 0.8 to 1.2.
2. The immersion tube for vacuum-refining molten steel, as claimed in Claim 1, characterized by.:
said immersion tube having a length within the range of from 700 to 1 ,000 mm, said inner bore of said immersion tube having a diameter within the range of from 300 to 700 mm, and the number of said magnesiachrome fired radial bricks (9) being within the range of from 60 to 1 80.
3. A pair of immersion tubes for vacuumrefining molten steel, substantially as hereinbefore described with reference to, and as illustrated in, Figures 3 and 4 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15825283A JPS6050111A (en) | 1983-08-29 | 1983-08-29 | Immersion pipe for rh |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8421294D0 GB8421294D0 (en) | 1984-09-26 |
| GB2145740A true GB2145740A (en) | 1985-04-03 |
| GB2145740B GB2145740B (en) | 1986-07-09 |
Family
ID=15667564
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08421294A Expired GB2145740B (en) | 1983-08-29 | 1984-08-22 | Immersion tube for vacuum-refining molten steel |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS6050111A (en) |
| DE (1) | DE3431787C2 (en) |
| GB (1) | GB2145740B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5024421A (en) * | 1990-05-08 | 1991-06-18 | Usx Corporation | Interlocking snorkel refractory |
| WO1996003530A1 (en) * | 1994-07-26 | 1996-02-08 | Veitsch-Radex Aktiengesellschaft Für Feuerfeste Erzeugnisse | Gas flushing device in the blowpipe of a vacuum degassing vessel |
| FR2728589A1 (en) * | 1994-12-27 | 1996-06-28 | Lorraine Laminage | Device for treating liq. steel under vacuum |
| GB2299344A (en) * | 1995-03-30 | 1996-10-02 | Veitsch Radex Ag | Snorkel for a degassing vessel |
-
1983
- 1983-08-29 JP JP15825283A patent/JPS6050111A/en active Granted
-
1984
- 1984-08-22 GB GB08421294A patent/GB2145740B/en not_active Expired
- 1984-08-29 DE DE19843431787 patent/DE3431787C2/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5024421A (en) * | 1990-05-08 | 1991-06-18 | Usx Corporation | Interlocking snorkel refractory |
| WO1996003530A1 (en) * | 1994-07-26 | 1996-02-08 | Veitsch-Radex Aktiengesellschaft Für Feuerfeste Erzeugnisse | Gas flushing device in the blowpipe of a vacuum degassing vessel |
| US5853658A (en) * | 1994-07-26 | 1998-12-29 | Veitsch-Radex Aktiengesellschaft Fur Feuerfeste Erzeugnisse | Gas purging device in the blowpipe of a degassing vessel |
| FR2728589A1 (en) * | 1994-12-27 | 1996-06-28 | Lorraine Laminage | Device for treating liq. steel under vacuum |
| GB2299344A (en) * | 1995-03-30 | 1996-10-02 | Veitsch Radex Ag | Snorkel for a degassing vessel |
| GB2299344B (en) * | 1995-03-30 | 1999-02-03 | Veitsch Radex Ag | Snorkel for a degassing vessel |
| US5911946A (en) * | 1995-03-30 | 1999-06-15 | Veitsch-Radex Aktiengesellschaft Fur Feuerfeste Erzeugnisse | Snorkel for a degassing vessel |
| ES2145645A1 (en) * | 1995-03-30 | 2000-07-01 | Veitsch Radex Ag | Snorkel for a degassing vessel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6050111A (en) | 1985-03-19 |
| DE3431787C2 (en) | 1986-04-10 |
| DE3431787A1 (en) | 1985-05-02 |
| JPH0135891B2 (en) | 1989-07-27 |
| GB8421294D0 (en) | 1984-09-26 |
| GB2145740B (en) | 1986-07-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19980822 |