The present invention relates generally to an impact pad for a metallurgical vessel, and more particularly to an impact pad that reduces wear to the wall of a metallurgical vessel by controlling the flow of an incoming stream of molten metal to minimize splashing and turbulence. The present invention is particularly applicable for use in ladles used in handling molten steel, and will be described with particular reference thereto.
Molten metal, in particular molten steel, is often poured from one metallurgical vessel to another. For example, molten metal may be poured from a furnace into a ladle, and then from a ladle into a tundish and from a tundish into a mold. Ladles typically have a generally horizontal or flat circular bottom with a vertically arranged side wall, sometimes referred to as a “barrel.” The bottom and side wall have a lining made of refractory materials. It is known to use impact pads to try to control the incoming stream of molten metal to reduce erosion of the lining, and to effect certain desirable flow patterns inside the ladle. Accordingly, an impact pad may be located in the bottom lining to receive the impact of the stream of molten metal as it is being poured into the ladle.
The worst wear to ladles is often observed in the region where the bottom meets the side wall proximate to the impact pad. High wear occurs in this region due to splashing and turbulence of the molten metal as it hits the impact pad.
Prior efforts to reduce wear to the ladle include the following: providing a raised or thicker impact area in the bottom of the ladle; casting wall protectors proximate to the impact pad; using domed or pyramid shaped impact pads to divide liquid flow; using higher quality and/or thicker bricks for the side wall of the ladle proximate to the impact area; and combinations thereof.
Each of the foregoing approaches has drawbacks. In this regard, providing a raised or thicker impact area in the bottom of the ladle may increase the life of the impact pad, but it does not provide protection for the ladle side wall. Casting wall protectors requires significant labor and downtime to set a form, cast and set the castable material, and remove the form following setting of the castable material. Domed and pyramid shaped impact pads may redirect flow of the molten metal to other regions of the ladle, but do not minimize turbulence. Consequently, wear may simply occur in a different region of the ladle. Using higher quality and/or thicker bricks for the side wall requires additional expense that does not address the underlying cause of the wear problem.
The present invention overcomes these and other problems and provides an impact pad that controls the flow of the molten metal to reduce wear to a metallurgical vessel caused by splashing and turbulence of the molten metal.
In accordance with the present invention, there is provided an impact pad for receiving a stream of molten metal in a ladle. The impact pad comprises: (a) a bottom wall portion with an upper surface against which the molten metal is intended to impact, said bottom wall portion comprised of a plurality of refractory bricks; and (b) a frame portion surrounding the bottom wall portion and comprised of a cast refractory material. The frame portion includes first and second side walls extending in an upward direction along the periphery of the bottom wall portion, and a rear wall extending in an upward direction along the periphery of the bottom wall portion.
In accordance with another aspect of the present invention, there is provided a lining for a bottom of a ladle. The lining comprises: (1) an impact pad comprised of: (a) a bottom wall portion with an upper surface against which the molten metal is intended to impact, said bottom wall portion comprised of a plurality of refractory bricks; (b) a frame portion surrounding the bottom wall portion and comprised of a cast refractory material, said frame portion having: first and second side walls extending in an upward direction along the periphery of the bottom wall portion, and a rear wall extending in an upward direction along the periphery of the bottom wall portion; and (2) a monolithic slab of a high-temperature refractory material encasing said impact pad.
In accordance with yet another aspect of the present invention, there is provided a lining for a bottom of a ladle. The lining comprises: (1) an impact pad comprised of: (a) a bottom wall portion with an upper surface against which the molten metal is intended to impact; (b) a frame portion surrounding the bottom wall portion and comprised of a cast refractory material, said frame portion integrally cast with said bottom wall portion, said frame portion having: first and second side walls extending in an upward direction along the periphery of the bottom wall portion, and a rear wall extending in an upward direction along the periphery of the bottom wall portion; and (2) a monolithic slab of a high-temperature refractory material encasing said impact pad. The first and second side walls and said rear wall of the impact pad extend above an upper surface of said monolithic slab.
An advantage of the present invention is the provision of an impact pad for controlling the flow of molten metal poured into a metallurgical vessel to reduce wear to the vessel.
Another advantage of the present invention is the provision of an impact pad that minimizes splashing of molten metal poured into a metallurgical vessel.
A still further advantage of the present invention is the provision of an impact pad that minimizes turbulence in molten metal poured into a metallurgical vessel.
Still another advantage of the present invention is the provision of an impact pad that eliminates the need to use higher quality and/or thicker bricks in the lining of a metallurgical vessel in order to reduce wear thereto.
Yet another advantage of the present invention is the provision of an impact pad that reduces wear to a metallurgical vessel at less cost and with less time consumption than prior art approaches for reducing wear.
These and other advantages will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims.
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:
Referring now to the drawings wherein the showings are for the purposes of illustrating a preferred embodiment of the invention only and not for the purposes of limiting same,
A refractory lining 52, comprised of two layers of refractory brick 54, is disposed along the inner surface of side wall 46. In the embodiment shown, refractory lining 52 of refractory bricks 54 extends along the entire side of shell 42 from bottom 44 to the open upper end of ladle 40, as best seen in
A bottom lining 60 (best seen in
U.S. Pat. No. 6,673,306 entitled “Refractory Lining For Metallurgical Vessel” and U.S. Pat. No. 6,787,098 entitled “Refractory Lining For Metallurgical Vessel,” which are expressly incorporated herein by reference, describe bottom linings for ladles that are both pre-formed and cast-in-place.
Refractory material 72 used to form slab 70 is selected based upon the desired operating characteristics and performance parameters of bottom lining 60. Various high-temperature refractory castables may find advantageous application in the present invention. In one embodiment of the present invention, a low-moisture, high alumina castable, manufactured and sold by North American Refractories Co. under the trade designations D-CAST 85 GOLD or HP-CAST ULTRA is used. Castables having 80% alumina content or higher are preferred.
Slab 70 is essentially circular in shape, and is dimensioned to match the circular opening in the bottom of ladle 40. It should be appreciated that ladle 40 may have an oval shape in which case bottom lining 60 would have an oval configuration to conform with the same. Slab 70 is formed to have a recess 76, best seen in
Multiple embodiments of an impact pad according to the present invention are disclosed herein. In the drawings of each embodiment, similar components bear the same reference numbers.
Impact pad 100, illustrating a first embodiment of the present invention, is positioned within ladle 40 to receive a stream of molten metal (not shown). As best seen in
Frame portion 122 has a pair of side walls 130, a rear wall 150 and a front wall 160. Each side wall 130 has an inwardly extending lower section 132 and an upper section 136. One or more openings 138 extend through upper section 136 of side walls 130, as best seen in
Frame portion 122 of impact pad 100 is formed by conventional molding techniques, known to those skilled in the art. Frame portion 122 may be formed of many different types of refractory materials, but in a preferred embodiment, is formed of a high alumina refractory manufactured and sold by North American Refractories Co., Pittsburgh, Pa., under the trade designations D-CAST 85 GOLD, HP-CAST ULTRA or HP-CAST 94MA-C.
As best seen in
In the embodiment shown, bottom wall portion 102 is comprised of a plurality of tightly packed high-density and high-temperature refractory bricks 110 arranged in an upright, soldiered configuration. As used herein, the term “high density” refers to a refractory brick having an initial density of at least 180 lb/ft3. The term “high temperature” refers to a brick capable of withstanding at least 2,900° F., the approximate melting temperature of steel.
Walls 130, 150, 160 and bottom wall portion 102 collectively define an interior cavity 115 of impact pad 100. Walls 130, 150 and 160 extend above refractory slab 70 and upper surface 106 of bottom wall portion 102. Molten metal is captured inside interior cavity 115. The inward projecting ledge formed by wall 170 helps maintain molten metal within interior cavity 115 .
As discussed above, and illustrated herein, bottom lining 60 may be formed as a pre-assembled, unitary bottom lining. Accordingly, frame portion 122 of impact pad 100 is cast around refractory bricks 110 in a first mold, and then impact pad 100 is placed into a second mold (not shown) to cast slab 70 in place around frame portion 122 of impact pad 100. As shown in
In an alternative method of assembly, bottom lining 60 is cast-in-place. Accordingly, frame portion 122 is cast around refractory bricks 110 in a mold, and then placed within ladle 40, where slab 70 is cast in place around frame portion 122. It should be understood that U-shaped slots 78 and 158, and gap 82 will not be present when bottom lining 60 is cast-in-place, since refractory material will fill any existing gaps during casting. It should be appreciated that bricks 110 of bottom wall portion 102 may be located within frame portion 122 at any suitable time during assembly of bottom lining 60.
Anchors or clips (not shown) may be embedded in frame portion 122 and slab 70 to reinforce the secure engagement of impact pad 100 with slab 70.
In the embodiment of the present invention shown in
Further embodiments of an impact pad according to the present invention will now be described with reference to
Referring now to
In the embodiment of the present invention shown in
In the embodiment of the present invention shown in
Referring now to
It should be understood that an impact pad, according to the present invention, may assume other shapes and configurations, and may be disposed in other regions of bottom lining 60, without deviating from the present invention. Furthermore, in an alternative embodiment of the present invention all or at least a portion of the refractory cast material of slab 70 may be substituted with refractory bricks. It should be further appreciated that each embodiment of the impact pad described above may be modified to incorporate one or more features of the other embodiments.
Other modifications and alterations will occur to others upon their reading and understanding of the specification. 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.
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