Information
-
Patent Grant
-
6763981
-
Patent Number
6,763,981
-
Date Filed
Monday, April 29, 200222 years ago
-
Date Issued
Tuesday, July 20, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 222 591
- 222 594
- 222 597
-
International Classifications
-
Abstract
A well block for use in a refractory lining in a metallurgical vessel for holding molten metal. The well block is comprised of a body formed of a refractory material. The body has a top surface, a bottom surface, an inner surface defining a bore that extends through the body from the top surface to the bottom surface, and a double-curved outer surface having at least one peak or valley formed thereon.
Description
FIELD OF THE INVENTION
The present invention relates to refractory components, and more particularly to well blocks and pocket blocks for use in metallurgical vessels for conveying molten metals.
BACKGROUND OF THE INVENTION
The handling of high-temperature liquids, such as molten steel, requires special materials and techniques. Ladles used for handling molten steel are comprised of an outer metallic shell that is lined with a refractory material. The inner surface of the metallic shell is typically lined with one or more layers of a refractory brick that can withstand extremely high temperatures and harsh, abrasive conditions. A “well block” is disposed within the refractory lining of the metallurgical vessel. A well block is a refractory component having a bore therethrough to allow molten metal within the vessel to exit therefrom. The well block must be fixedly secured within the refractory lining to prevent the block from separating, i.e., floating, from the refractory lining on the bottom of the vessel during operation. To this end, it has been known to form well blocks having a step at the bottom thereof or to taper the well block from top to bottom to prevent the aforementioned floating or separation. It is also important that the well block be designed to retard penetration of molten metal along the interface between the well block and the refractory lining.
Steel ladles of the type heretofore described have a limited service life, after which the ladle must be relined. Advances in refractory brick technology have increased the service life of the refractory linings to where a brick lining may undergo 80 to 120 “heats,” i.e., use, before it is necessary to reline the ladle. However, conventional well blocks cannot withstand the repeated heating cycles of such a level of many ladle bricks now available. In this respect, conventional well blocks are formed by casting a refractory material, or by an air-ramming process. Air-rammed well blocks have a limited service life because it is difficult to obtain a block with good density by this process. A cast well block provides substantially better performance than an air-rammed block, but even a cast well block cannot provide the service life of newer refractory linings. As a result, multiple well block changes are typically required during the life of the refractory lining.
The present invention provides a well block having a service life that exceeds those of cast or rammed well blocks, and provides a well block that is designed to lock into a refractory lining and reduce metal penetration along the block-refractory lining interface.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention, there is provided a well block for use in a refractory lining in a metallurgical vessel for holding molten metal. The well block is comprised of a body formed of a refractory material. The body has a top surface, a bottom surface, an inner surface defining a bore that extends through the body from the top surface to the bottom surface, and a double-curved outer surface having at least one peak or valley formed thereon.
In accordance with another aspect of the present invention, there is provided an isopressed well block for use in a refractory lining in a metallurgical vessel for holding molten metal. The well block has a body having a top surface, a bottom surface, an inner surface defining a bore that extends through the body from the top surface to the bottom surface. The refractory material is comprised of 5 to 95% by weight of a material selected from the group consisting of alumina in the form of tabular alumina, white fused alumina, brown fused alumina, bauxite or combinations of those materials, magnesium oxide (MgO), silica (SiO
2
), zirconium oxide (ZrO
2
), mullite (3 Al
2
O
3
.2 SiO
2
) and combinations thereof, 1 to 25% by weight carbon, and 0 to 15% of an antioxidant.
It is an object of the present invention to provide a well block for use in a refractory lining in a metallurgical vessel.
It is another object of the present invention to provide a well block as described above that has a service life exceeding conventional, cast or air-rammed well blocks.
It is another object of the present invention to provide a well block as described above that is isopressed.
It is another object of the present invention to provide a well block as described above that is less susceptible to separation from the refractory lining during use.
Another object of the present invention is to provide a well block as described above that minimizes penetration of molten metal along the refractory block-refractory lining interface.
Another object of the present invention is to provide a well block as described above having a bore diameter that minimizes turbulence and reduces wear from the flow of molten metal therethrough.
These and other objects will become apparent from the following description of a preferred embodiment and invention, taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in the specification and illustrated in the accompanying drawings which form a part hereof, and wherein:
FIG. 1
is a sectional view of the bottom portion of a steel ladle, showing a well block illustrating a preferred embodiment of the present invention;
FIG. 2
is a partially sectioned, elevational view of the well block shown in
FIG. 1
; and
FIG. 3
is a partially sectioned, top plan view of the well block shown in FIG.
1
.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, the present invention relates generally to a refractory well block for use in a metallurgical vessel used in handling molten metal, and will be described with particular reference thereto. It would be appreciated from a further reading of the specification, that the invention is not limited to a particular design or use, but may find advantageous application for use in metallurgical vessels handling many types of molten metal.
FIG. 1
shows the bottom end of a conventional steel ladle
10
having an outer metallic shell
12
and an inner refractory lining
22
. Outer metallic shell
12
is comprised of a cup-shaped bottom
14
having an opening
16
therein, and a slightly conical side wall
18
. Refractory lining
22
is comprised of a bottom refractory lining
24
and a side refractory lining
26
. In the embodiment shown, bottom refractory lining
24
is a cast monolith. Side refractory lining
26
is comprise of two layers of refractory brick
28
that rest upon bottom refractory lining
24
. Disposed within bottom refractory lining
24
in registry with opening
16
is a well block
30
, best illustrated in
FIGS. 2 and 3
.
Well block
30
is generally tubular in shape and has a top surface
32
, a bottom surface
34
, an inner surface
36
and an outer surface
38
. In the embodiment shown, top and bottom surfaces
32
,
34
are flat and parallel to each other. Inner surface
36
is comprised of a first surface portion
36
a
that defines a bore
42
that extends through well block
30
. Bore
42
is tapered from top surface
32
to bottom surface
34
. Bore
42
may be circular in cross-section, but in accordance with one aspect of the present, preferably has an oval or elliptical cross-section to facilitate smooth laminar flow of molten metal therethrough. A second surface portion
36
b
defines a shallow, annular recess
44
at the top end of well block
30
.
In accordance with one aspect of the present invention, outer surface
38
is comprised of first “ruled surface portions”
38
a
-that are disposed at the ends of well block
30
. As used herein, the term “ruled surface” shall refer to a surface generated by a straight line. Disposed between ruled surface portion
38
a
is a double-curved surface portion
38
b
. As used herein the term “double curved surface portion” shall refer to a surface that has no straight line elements and that is curved in every direction. In the embodiment shown, ruled surface portion
38
a
and double curved surface portion
38
b
are surfaces of rotation defined by rotation of a straight line and a curved line, respectively, about an axis designated “A.” In this respect, ruled surface portions
38
a
are cylindrical in shape, and well block
30
, as a whole, has a generally cylindrical configuration. Block
30
is generally symmetrical about axis A. As will be appreciated from a further reading of the specification, surface portions
38
a
,
38
b
may also be generated by revolving straight and curved lines about a non-circular, closed path, such as by way of example and not limitation, an elliptical path and an oval path. In the embodiment shown, double curved surface portion
38
b
is a surface revolution generated by revolving a smooth, curved, serpentine line having peaks and valley about axis A, wherein a plurality of annular ridges and recesses that extend around well block
30
are formed. Ruled surface portions
38
a
join double curved surface portion
38
b
without any sharp corners. In other words, outer surface
38
b
has a continuous, smooth profile from top surface
32
to bottom surface
34
.
A well block
30
of the type heretofore described may be formed of a conventional, high temperature refractory material typically used in such applications and find advantageous application in a steel ladle. However, in accordance with another aspect of the present invention, refractory block
30
is formed by an isopressing process. Isopressing refractory block
30
facilitates use of certain refractory materials that do not lend themselves to casting or air-ramming techniques. Moreover, isopressing block
30
provides a denser structure than could be obtained by casting or air-ramming.
Broadly stated, an isopressed refractory block
30
according to the present invention is comprised of:
5 to 95% by weight of a refractory aggregate;
1 to 25% by weight carbon;
0 to 15% by weight of an antioxidant; and
a resin binder.
By way of example, and not limitation, the refractory aggregate may be formed of alumina in the form of tabular alumina, white fused alumina, brown fused alumina, bauxite or combinations of those materials, magnesium oxide (MgO), silica (SiO
2
), zirconium oxide (ZrO
2
), mullite (3 Al
2
O
3
.2 SiO
2
) and combinations thereof. As will be appreciated by those skilled in the art, other types of refractory material may also be used.
The carbon may take the form of graphite. In this respect, isopressing facilitates the use of graphite, which cannot be cast into a well block without the use of high water contents that would result in low density shapes. Additionally, it is appreciated by those skilled in the art that shapes containing carbon such as flake graphite are not easily air-rammed, and that air-rammed shapes containing such materials also have low density.
Conventional antioxidants, such as aluminum, silicon and boron or boron compounds such as boron carbide, are suitable for use in forming block
30
.
Resin binders that may be used to form refractory block
30
are epoxies, urethanes, phenolic resins or other thermosetting resins.
It will be appreciated that other materials can be substituted without departing from the spirit of the invention.
In a preferred embodiment, isopressed refractory block
30
is comprised of about 73% alumina, about 16% magnesia, about 4% flake graphite, about 6% antioxidants and carbon filler, along with a phenolic resin binder.
Referring now to use of well block
30
, well block
30
is adapted to be placed on cup-shaped bottom
14
of ladle
10
with bore
42
aligned with opening
16
. Bottom refractory lining
24
is cast around well block
30
, wherein well block
30
is locked into position within bottom refractory lining
24
filling valleys
54
. Annular ridges
52
essentially lock the well block within bottom refractory lining
24
. Any tendency to move or float from bottom refractory lining
24
is prevented by ridges
52
and recesses
54
interlocking with corresponding ridges and recesses formed by the surrounding refractory forming bottom refractory lining
24
. In one respect, corrugated or serpentine shape of double curved surface portion
38
b
reduces the likelihood of molten metal penetrating along the interface between well block
30
and bottom refractory lining
24
as compared to a cylindrical well block in that the curving corrugated surface area of well block
30
creates a longer path for molten metal to penetrate as compared to a straight, cylindrical surface in conventional well blocks. Further, a smooth, contoured outer surface
38
of well block
30
reduces the likelihood of stress fractures occurring at stress concentration points typically found in shelved or stepped well blocks.
Still further, isopressing refractory block
30
provides a well block capable of utilizing some refractory materials not suitable for a casting process, and a well block that is denser than could be obtained by a ramming or casting process. The present invention thus provides an isopressed well block
30
that has a service life that exceeds a conventional cast or rammed well block, in that isopressing allows for use of materials (e.g., graphite) not suitable for casting or ramming techniques in a well block that is denser than could be obtained in a casting or ramming process. Moreover, a well block
30
according to the present invention has an outer contour that facilitates locking well block
30
within bottom refractory lining
24
and that reduces the likelihood of metal penetration along the block/lining interface.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purposes of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. For example, while the outer surface of well block
30
has been described with annular ridges and recesses, any other double curved surfaces may find advantageous application in the present invention. The outer surface of well block
30
may have a plurality of smoothly curved, individual dimples that are randomly spaced along the outer surface thereof. Likewise, ridges may be staggered, serpentine, set at an angle relative to axis A or be intersecting. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
Claims
- 1. A well block for use in a refractory lining in a metallurgical vessel for holding molten metal, said well block comprised of: a body formed of a refractory material, said body having a top surface, a bottom surface, an inner surface defining a bore that extends through said body form said top surface to said bottom surface, and a double-curved outer surface having a plurality of separate annular ridges and valleys formed thereon that extend around said well block.
- 2. A well block as defined in claim 1, wherein said double-curved outer surface is a surface defined by revolving a curved surface about an axis through said body.
- 3. A well block as defined in claim 2, wherein said bore is symmetrical to said axis.
- 4. A well block as defined in claim 3, wherein said curved surface is a serpentine line that defines said plurality of annular ridges and valleys.
- 5. A well block as defined in claim 4, wherein said well block is isopressed.
- 6. A well block as defined in claim 5, wherein said bore tapers inwardly from said top surface to said bottom surface.
- 7. A well block as defined in claim 6, wherein said bore has a non-circular cross-section.
- 8. A well block as defined in claim 7, wherein said bore is elliptical in cross-section.
- 9. A well block as defined in claim 4, wherein said well block is formed from a cast refractory.
- 10. A well block for use in a refractory lining in a metallurgical vessel for holding molten meta wherein said metallurgical vessel includes a bottom refractory lining, said well block comprised of:a body formed of a refractory material, said body having a top surface, a bottom surface, and an inner surface defining a bore that extends through said body from said top surface to said bottom surface, and a double-curved outer surface having a plurality of separate annular ridges and valleys formed thereon, wherein said bottom refractory lining is cast around said body.
- 11. A well block as defined in claim 10, wherein said double-curved outer surface is defined by revolving a curved surface about an axis through said body.
- 12. A well block as defined in claim 11, wherein said bore is symmetrical to said axis.
- 13. A well block as defined in claim 12, wherein said curved surface is a serpentine line that defines a plurality of annular ridges and valleys that extend around said block.
- 14. A well block as defined in claim 13, wherein said well block is isopressed.
- 15. A well block as defined in claim 14, wherein said bore tapers inwardly from said top su face to said bottom surface.
- 16. A well block as defined in claim 15, wherein said bore has a non-circular cross-section.
- 17. A well block as defined in claim 16, wherein said bore is elliptical in cross-section.
- 18. A well block as defined in claim 13, wherein said well block is formed from a cast refractory.
US Referenced Citations (18)