CA2006351C - Purifying molten metal - Google Patents
Purifying molten metalInfo
- Publication number
- CA2006351C CA2006351C CA 2006351 CA2006351A CA2006351C CA 2006351 C CA2006351 C CA 2006351C CA 2006351 CA2006351 CA 2006351 CA 2006351 A CA2006351 A CA 2006351A CA 2006351 C CA2006351 C CA 2006351C
- Authority
- CA
- Canada
- Prior art keywords
- baffles
- tundish
- array
- metal
- molten metal
- Prior art date
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Abstract
The invention relates to a means of purifying molten metal, particularly steel, by the removal of impurities/inclusions during continuous casting. The molten metal (3) is passed in a tundish (1) through an array of vertical baffles (8) that are spaced apart transversely across the tundish to provide restricted flow channels (12). The baffles (8) may be flat boards or tiles (9a,9b) and are preferably used in contact with a weir (7) and dam (10), upstream and downstream respectively of the baffles. The speed and direction of flow of the molten metal can thereby be controlled and directed to give more effective dwell time in contact with a surface covering layer (11) of flux.
Description
- 2atC36351 PURIFYING MOLTEN METAL
This invention relates to a method and apparatus for purifying molten metal and is particularly applicable to purifying molten steel during the continuous casting process. For convenience the invention will hereafter be described with reference to steel only.
In the continuous casting of steel, molten steel is poured from a ladle into a continuous casting mould via an intermediate vessel which acts as a constant head reservoir and is called a tundish.
It is usual to treat the steel as initially produced at a stage before it is in the ladle and/or whilst it is in the ladle in order to remove undesired impurities or inclusions prior to pouring the steel into a tundish. These treatments are generally referred to collectively as secondary steelmaking processes, which include ladle slag removal, vacuum treatment, inert gas stirring, fluxing treatments or inert gas injection of powder reagents.
Furthermore, two or more of these processes may be combined in order to achieve high quality steels having particular regard for steel cleanness. However, a proportion of impurities, whether solid or liquid, always pass from the ladle to the tundish. In addition further inclusions e.g. oxide inclusions, may result from atmospheric oxidation of the molten steel as it flows from a ladle to a tundish.
This invention relates to a method and apparatus for purifying molten metal and is particularly applicable to purifying molten steel during the continuous casting process. For convenience the invention will hereafter be described with reference to steel only.
In the continuous casting of steel, molten steel is poured from a ladle into a continuous casting mould via an intermediate vessel which acts as a constant head reservoir and is called a tundish.
It is usual to treat the steel as initially produced at a stage before it is in the ladle and/or whilst it is in the ladle in order to remove undesired impurities or inclusions prior to pouring the steel into a tundish. These treatments are generally referred to collectively as secondary steelmaking processes, which include ladle slag removal, vacuum treatment, inert gas stirring, fluxing treatments or inert gas injection of powder reagents.
Furthermore, two or more of these processes may be combined in order to achieve high quality steels having particular regard for steel cleanness. However, a proportion of impurities, whether solid or liquid, always pass from the ladle to the tundish. In addition further inclusions e.g. oxide inclusions, may result from atmospheric oxidation of the molten steel as it flows from a ladle to a tundish.
There is also a tendency for the steel to pick up further impurities in the tundish and it has generally proven difficult and also rather costly to remove impurities from steel in a tundish although cover slags are of some use in this respect. Moreover once the steel has passed from the tundish into the mould it is difficult to remove impurities despite the limited effect that may be achieved by use of suitable mould fluxes.
It is understood that the expression "inclusions" includes indigenous and exogenous inclusions and furthermore the inclusions may be separate or in clusters. In any event, inclusions in the steel in the tundish can be harmful as a result of being deposited in the bore of the outlet nozzles including any extension thereof below the tundish extending towards the moulds or as a result of being transferred into the moulds where they may cause a deterioration in surface and internal quality and adversely affect the metallurgical properties of the steel being cast.
The present invention provides an effective means of reducing the inclusion content of steel leaving a tundish.
Accordingly, the invention provides in a first aspect, a method of purifying metal comprising passing the molten metal in a tundish past and between an array of vertical baffles located between the zone of arrival of the metal in the tundish from the ladle-and an outlet from the tlln~ish, the baffles of the array being spaced apart transversely across the tundish whereby flow of the molten metal is restricted to channels between the baffles, whereby removal of inclusions in the molten metal is enhanced.
In a second aspect the invention provides a tlln~; ch cont~i n i ng an array of vertical baffles between the arrival zone for molten metal and an outlet, the baffles of the array being spaced apart transversely across the tundish to provide flow channels between the baffles.
The baffles may be formed from any refractory or ceramic materials which are suitable for use in contact with molten steel e.g. formed from a high alumina containing particulate refractory bonded by e.g. a refractory cement. Alternatively, the baffles may be formed from suitable refractory materials and fired at high temperature prior to use.
.
The ceramic of the baffles may be a porous or cellular ceramic e.g. in the form of a cellular ceramic foam or in the form of an extruded cellular ceramic.
In another embodiment of the invention the ceramic of the baffles may be substantially solid or they may be a combination of cellular and solid ceramic.
The baffles may be flat e.g. boards, or tiles or, for example, shaped so as to define a tortuous, e.g. zig-zag, path. The tiles are preferably generally parallel and equidistant one to another which arrangement is particularly effective in controlling the flow velocity of the steel which in turn, enhances the separation of the inclusions passing through and between the baffles and subsequently when the steel contacts an inclusion absorbing flux.
In an altern,,ative 'embodiment the array of b~es~ybe fnrm~ ofor mayc~ ;~ oneor more portions o~ an extruded tubular or cellular body extending substantially from the floor of a tundish to the surface of any molten steel contained therein.
Each tubular body may have one or more bores extending therethrough. The cross sectional area of the bores may be circular, square or any other suitable geometric shape. Thus in this embodiment the array of baffles may be provided not as a series of separate articles but by a unitary body suitably constructed to provide the required flow channels.
The steel passes through and/or between the baffles which can themselves be valuable in picking up and retaining inclusions from the steel. The molten steel-contacting surfaces of the baffles may be smooth.
More preferably, however, their surfaces may be roughened or suitably shaped to enhance the absorption of impurities.
The inclusions which may be removed include, for example, aluminates, silicates, other oxides, sulphides, nitrides and carbides or combinations thereof.
A
It is understood that the expression "inclusions" includes indigenous and exogenous inclusions and furthermore the inclusions may be separate or in clusters. In any event, inclusions in the steel in the tundish can be harmful as a result of being deposited in the bore of the outlet nozzles including any extension thereof below the tundish extending towards the moulds or as a result of being transferred into the moulds where they may cause a deterioration in surface and internal quality and adversely affect the metallurgical properties of the steel being cast.
The present invention provides an effective means of reducing the inclusion content of steel leaving a tundish.
Accordingly, the invention provides in a first aspect, a method of purifying metal comprising passing the molten metal in a tundish past and between an array of vertical baffles located between the zone of arrival of the metal in the tundish from the ladle-and an outlet from the tlln~ish, the baffles of the array being spaced apart transversely across the tundish whereby flow of the molten metal is restricted to channels between the baffles, whereby removal of inclusions in the molten metal is enhanced.
In a second aspect the invention provides a tlln~; ch cont~i n i ng an array of vertical baffles between the arrival zone for molten metal and an outlet, the baffles of the array being spaced apart transversely across the tundish to provide flow channels between the baffles.
The baffles may be formed from any refractory or ceramic materials which are suitable for use in contact with molten steel e.g. formed from a high alumina containing particulate refractory bonded by e.g. a refractory cement. Alternatively, the baffles may be formed from suitable refractory materials and fired at high temperature prior to use.
.
The ceramic of the baffles may be a porous or cellular ceramic e.g. in the form of a cellular ceramic foam or in the form of an extruded cellular ceramic.
In another embodiment of the invention the ceramic of the baffles may be substantially solid or they may be a combination of cellular and solid ceramic.
The baffles may be flat e.g. boards, or tiles or, for example, shaped so as to define a tortuous, e.g. zig-zag, path. The tiles are preferably generally parallel and equidistant one to another which arrangement is particularly effective in controlling the flow velocity of the steel which in turn, enhances the separation of the inclusions passing through and between the baffles and subsequently when the steel contacts an inclusion absorbing flux.
In an altern,,ative 'embodiment the array of b~es~ybe fnrm~ ofor mayc~ ;~ oneor more portions o~ an extruded tubular or cellular body extending substantially from the floor of a tundish to the surface of any molten steel contained therein.
Each tubular body may have one or more bores extending therethrough. The cross sectional area of the bores may be circular, square or any other suitable geometric shape. Thus in this embodiment the array of baffles may be provided not as a series of separate articles but by a unitary body suitably constructed to provide the required flow channels.
The steel passes through and/or between the baffles which can themselves be valuable in picking up and retaining inclusions from the steel. The molten steel-contacting surfaces of the baffles may be smooth.
More preferably, however, their surfaces may be roughened or suitably shaped to enhance the absorption of impurities.
The inclusions which may be removed include, for example, aluminates, silicates, other oxides, sulphides, nitrides and carbides or combinations thereof.
A
Cellular ceramic baffles provide a relatively large surface area contacted by the steel and are particularly effective for removing alumina inclusions.
By use of an array of baffles according to the present invention, molten steel passing through the restricted width of the tundish between the baffles is thereby forced to increase its speed and this, particularly in conjunction with constraints to move the flow upwardly into contact with a surface-covering flux layer, can greatly improve the removal of inclusions. It will be appreciated that the speed of flow having increased through the baffles will gradually decrease and the direction of flow will change to horizontal and then downward, giving a more effective dwell time in contact with a surface covering layer of flux.
Preferably, the array of baffles is used in conjunction with a dam and weir arrangement and, preferably, this arrangement is in contact with or is in close proximity to the array.
Thus, in a preferred embodiment, there is positioned immediately downstream, of, and preferably in contact with the lower portions of, the baffles, a dam extending transversely across the floor of the tundish and over which the molten steel flows. The dam may extend across the entire width or a substantial portion of the width of the tundish.
2~;35~ ~
By use of an array of baffles according to the present invention, molten steel passing through the restricted width of the tundish between the baffles is thereby forced to increase its speed and this, particularly in conjunction with constraints to move the flow upwardly into contact with a surface-covering flux layer, can greatly improve the removal of inclusions. It will be appreciated that the speed of flow having increased through the baffles will gradually decrease and the direction of flow will change to horizontal and then downward, giving a more effective dwell time in contact with a surface covering layer of flux.
Preferably, the array of baffles is used in conjunction with a dam and weir arrangement and, preferably, this arrangement is in contact with or is in close proximity to the array.
Thus, in a preferred embodiment, there is positioned immediately downstream, of, and preferably in contact with the lower portions of, the baffles, a dam extending transversely across the floor of the tundish and over which the molten steel flows. The dam may extend across the entire width or a substantial portion of the width of the tundish.
2~;35~ ~
Additionally, there may be positioned immediately upstream of, and preferably in contact with the upper portions of, the baffles, a weir under which the molten steel flows. The weir may extend across the entire width or a substantial portion of the width of the tundish.
As indicated above, these arrangements are particularly advantageous in further increasing the velocity of the steel as it travels through the baffles since the effective cross-sectional area is reduced which in turn imparts an increase in steel velocity.
The increase in velocity together with the change in flow direction produced are particularly beneficial in ensuring that any inclusions are directed towards the covering flux.
Known methods of removing inclusions in a tundish e.g. using dams and weirs, are not wholly effective and generally are only capable of removing those inclusions greater than about 100 ~m. However, this performance is inadequate for steels destined for use in, for example, the manufacture of drawn and wall-ironed products for which case the inclusion size limit is generally about 50 ~m.
The method and apparatus of the present invention is able to reduce inclusions exceeding 10 ~m, which is a most satisfactory result.
As indicated above, these arrangements are particularly advantageous in further increasing the velocity of the steel as it travels through the baffles since the effective cross-sectional area is reduced which in turn imparts an increase in steel velocity.
The increase in velocity together with the change in flow direction produced are particularly beneficial in ensuring that any inclusions are directed towards the covering flux.
Known methods of removing inclusions in a tundish e.g. using dams and weirs, are not wholly effective and generally are only capable of removing those inclusions greater than about 100 ~m. However, this performance is inadequate for steels destined for use in, for example, the manufacture of drawn and wall-ironed products for which case the inclusion size limit is generally about 50 ~m.
The method and apparatus of the present invention is able to reduce inclusions exceeding 10 ~m, which is a most satisfactory result.
The improvements achieved by the arrangement of baffles of the invention serve to separate the inclusions from the steel in the follo~ing manner:
i) surface adsorption or filtration of inclusions onto the surface of the baffle boards, tiles or other shapes.
ii) formation of a generally upward flow of steel having a higher velocity initially and having a lower velocity at the covering flux/liquid steel interface together with a substantially horizontal steel flow at said interface, maximises the inclusion separation by flotation and subsequent capture by the inclusion-absorbing flux.
In the method and apparatus of the invention means may be incorporated for introducing inert and/or non-oxidising gases into the steel integrally with the array or adjacent thereto. For; ~'.c ~ m~ybe achieved by means of the array having a gas-permeable portion through which gas can pass outwardly into the steel and ducting for the supply of gas to the gas-permeable portion. Alternatively, known gas-purging means used in tundishes may be employed.
In addition to the arrangements described above, one or more baffles, dams and/or weirs may, if desired, be positioned in the downstream zone of a tundish.
~4 The invention is further described with reference to the accompanying drawings in which:
Figure 1 is half of a symmetrical tundish, sectioned along its length, in accordance with one embodiment of the invention.
Figure 2 is an enlarged Yertical section viewed from the downstream side of an array of ceramic baffles schematically indicated in Figure 1.
Figure 3 is a schematic vertical section along the length of part of a tundish to show the velocity vectors produced in the tundish.
Figure 4 is a graphical representation illustrating the relationship between the maximum inclusion size passing through a tundish and the free flow area defined by the array of Figure 2.
Figure 5 is a diagram showing the inclusion size distribution at the inlet and the outlet from a tundish equipped in accordance with the invention.
Referring now to Figure 1 a tundish assembly 1 has an outer metal casing 2 and an inner refractory lining (not shown) containing molten steel 3. A stream 4 of molten steel 3 is introduced to the tundish 1 via an impact zone 5.
.
`
i) surface adsorption or filtration of inclusions onto the surface of the baffle boards, tiles or other shapes.
ii) formation of a generally upward flow of steel having a higher velocity initially and having a lower velocity at the covering flux/liquid steel interface together with a substantially horizontal steel flow at said interface, maximises the inclusion separation by flotation and subsequent capture by the inclusion-absorbing flux.
In the method and apparatus of the invention means may be incorporated for introducing inert and/or non-oxidising gases into the steel integrally with the array or adjacent thereto. For; ~'.c ~ m~ybe achieved by means of the array having a gas-permeable portion through which gas can pass outwardly into the steel and ducting for the supply of gas to the gas-permeable portion. Alternatively, known gas-purging means used in tundishes may be employed.
In addition to the arrangements described above, one or more baffles, dams and/or weirs may, if desired, be positioned in the downstream zone of a tundish.
~4 The invention is further described with reference to the accompanying drawings in which:
Figure 1 is half of a symmetrical tundish, sectioned along its length, in accordance with one embodiment of the invention.
Figure 2 is an enlarged Yertical section viewed from the downstream side of an array of ceramic baffles schematically indicated in Figure 1.
Figure 3 is a schematic vertical section along the length of part of a tundish to show the velocity vectors produced in the tundish.
Figure 4 is a graphical representation illustrating the relationship between the maximum inclusion size passing through a tundish and the free flow area defined by the array of Figure 2.
Figure 5 is a diagram showing the inclusion size distribution at the inlet and the outlet from a tundish equipped in accordance with the invention.
Referring now to Figure 1 a tundish assembly 1 has an outer metal casing 2 and an inner refractory lining (not shown) containing molten steel 3. A stream 4 of molten steel 3 is introduced to the tundish 1 via an impact zone 5.
.
`
In relation to the general direction of flow of steel through the tundish, X signifies the upstream side i.e. the side nearer the zone of entry of steel into the tundish and Y the downstream side i.e. the side nearer an outlet nozzle 6 from which the steel exits the tundish.
A refractory board 7 serves as a partition or weir which is suspended between the upstream and downstream zones of the tundish and which in addition acts as a partial barrier of the upper part of the upstream side of baffles 8. The baffles consist of a plurality of equidistant vertically disposed ceramic tiles 9 (only the side of one tile being visible.) The lower part of the array 8 on the downstream side has a barrier wall or dam 10. In use this arrangement produces an upward flow of steel passing between the ceramic tiles 9 and directs the steel towards a surface layer of inclusion-absorbing flux 11 prior to the steel leaving the tundish via a nozzle 6.
The array 8 comprising a plurality of ceramic tiles 9 indicated only schematically in Figure 1 is an array having the structure shown diagramatically in Figure 2. Thus, the array 8 has nine vertically disposed ceramic tiles 9a, 9b placed substantially equidistantly apart across the width of a tundish. The total area of the channels 12 formed between the tiles 9a, 9b, define the free flow area of the tundish through the array.
n D - :
2~ s~
A refractory board 7 serves as a partition or weir which is suspended between the upstream and downstream zones of the tundish and which in addition acts as a partial barrier of the upper part of the upstream side of baffles 8. The baffles consist of a plurality of equidistant vertically disposed ceramic tiles 9 (only the side of one tile being visible.) The lower part of the array 8 on the downstream side has a barrier wall or dam 10. In use this arrangement produces an upward flow of steel passing between the ceramic tiles 9 and directs the steel towards a surface layer of inclusion-absorbing flux 11 prior to the steel leaving the tundish via a nozzle 6.
The array 8 comprising a plurality of ceramic tiles 9 indicated only schematically in Figure 1 is an array having the structure shown diagramatically in Figure 2. Thus, the array 8 has nine vertically disposed ceramic tiles 9a, 9b placed substantially equidistantly apart across the width of a tundish. The total area of the channels 12 formed between the tiles 9a, 9b, define the free flow area of the tundish through the array.
n D - :
2~ s~
Referring now to Figure 3, the velocity vectors produced in a tundish according to this invention are shown by long-tailed arrows 13 and shorter-tailed arrows 14. The optional use of a down-stream dam 15 is also shown. The arrows 13 depict zones of increased velocity and arrows 14 show zones of lower velocity.
In use the lower velocity is particularly advantageous as indicated at the interface between the molten steel 3 and the inclusion absorbing flux 11 as the change of velocity accompanied by a change in direction enables significant amounts of sub 100 ~m inclusions to be removed.
As can be seen from Figure 4, the ability of the system to remove inclusions at first increases with decrease of free flow area through the baffles and then passes an optimum point after which the ability decreases and, clearly, the best arrangement for any particular embodiment of the invention will be determinable by the skilled man of the art.
EXAMPLE
In a large scale laboratory experimental evaluation a tundish having a capacity of 600 kg was used. The exit nozzle had a nominal diameter of 26 mm.
A vertical array of ceramic tiles was introduced into the tundish and arranged substantially in the manner as illustrated in Figure 1. This assembly was used to cast an ingot weighing approximately 3500 kg. A series of dip samples were taken at regular intervals from both the upstream and downstream zones of the tundish throughout the duration of the casting cycle which lasted for 330 seconds. The results from these samples are shown in Figure 5 which relates to an alumina cluster count for each sample from the inlet (unfiltered) and outlet (filtered) zones of the tundish. The total alumina (Al203) cluster area was Galculated for each sample and the mean value determined.
The filtered results are significantly better than the unfiltered (inlet) ones showing that the tundish assembly of the present invention and its methods of its use are most satisfactory.
In use the lower velocity is particularly advantageous as indicated at the interface between the molten steel 3 and the inclusion absorbing flux 11 as the change of velocity accompanied by a change in direction enables significant amounts of sub 100 ~m inclusions to be removed.
As can be seen from Figure 4, the ability of the system to remove inclusions at first increases with decrease of free flow area through the baffles and then passes an optimum point after which the ability decreases and, clearly, the best arrangement for any particular embodiment of the invention will be determinable by the skilled man of the art.
EXAMPLE
In a large scale laboratory experimental evaluation a tundish having a capacity of 600 kg was used. The exit nozzle had a nominal diameter of 26 mm.
A vertical array of ceramic tiles was introduced into the tundish and arranged substantially in the manner as illustrated in Figure 1. This assembly was used to cast an ingot weighing approximately 3500 kg. A series of dip samples were taken at regular intervals from both the upstream and downstream zones of the tundish throughout the duration of the casting cycle which lasted for 330 seconds. The results from these samples are shown in Figure 5 which relates to an alumina cluster count for each sample from the inlet (unfiltered) and outlet (filtered) zones of the tundish. The total alumina (Al203) cluster area was Galculated for each sample and the mean value determined.
The filtered results are significantly better than the unfiltered (inlet) ones showing that the tundish assembly of the present invention and its methods of its use are most satisfactory.
Claims (30)
1. A method of purifying metal in a tundish comprising passing said metal in molten form between a zone of arrival and an outlet and past baffles located between said zone of arrival and the outlet, in which the metal is passed past and between an array of said baffles, the baffles of the array extending vertically and being spaced apart transversely across the tundish whereby flow of the molten metal is restricted to channels between the baffles, whereby removal of inclusions in the molten metal is enhanced.
2. A method according to claim 1, in which there is positioned immediately downstream of the array of baffles a dam extending transversely across the floor of the tundish for at least a substantial portion of its width and over which the metal must flow.
3. A method according to claim 1 or 2, in which there is positioned immediately upstream of the array of baffles a weir extending transversely across the tundish for at least a substantial portion of its width and under which the metal must flow.
4. A method according to claim 1, in which the baffles are flat tiles.
5. A method according to claim 1, in which the baffles are tiles shaped to define a tortuous path.
6. A method according to claim 4 or 5, in which the tiles are positioned parallel to each other.
7. A method according to claim 4 or 5, in which the tiles are equidistant from each other.
8. A method according to claim 1, in which the array of baffles is in the form of a unitary body of extruded tubular or cellular form extending from the floor of the tundish to the surface of any molten metal contained therein.
9. A method according to claim 1, in which at least one further baffle, dam or weir is positioned downstream from the array of baffles.
10. A tundish having a floor and sidewalls and an arrival zone and outlet for molten metal, the tundish containing an array of vertical baffles located between said arrival zone and the outlet, the baffles of the array being spaced apart transversely across the tundish to provide flow channels between the baffles.
11. A tundish according to claim 10, in which the baffles are of a high alumina ceramic material containing refractory particulates bonded by refractory cement.
12. A tundish according to claim 10 or 11, in which immediately on the downstream side of the array of baffles is a dam extending transversely across the floor of the tundish for at least a substantial portion of its width.
13. A tundish according to claim 10 or 11, in which immediately on the upstream side of the array of baffles is a weir extending transversely across the tundish for at least a substantial portion of its width.
14. A tundish according to claim 10, in which the baffles are flat tiles which are parallel to each other.
15. A tundish according to claim 10 or 14, in which the baffles are tiles which are equidistant from each other.
16. A method of purifying metal in a tundish having a zone of arrival and an outlet, with an array of vertical baffles located between the zone of arrival and the outlet, the baffles of the array being spaced apart transversely across the tundish so that flow of the molten metal is restricted to channels between the baffles; said method comprising the steps of passing molten metal between the zone of arrival and the outlet past and between the baffles so that the metal increases its speed as it moves past the baffles, the speed increase enhancing the removal of inclusions from the molten metal.
17. A method according to claim 16, in which there is positioned immediately downstream of the array of baffles a dam extending transversely across the floor of the tundish for at least a substantial portion of its width and over which the metal must flow.
18. A method according to claim 16, in which the baffles are tiles shaped to define a tortuous path.
19. A method according to claim 16, in which at least one further baffle, dam or weir is positioned downstream from the array of baffles.
20. A tundish comprising:
a floor and sidewalls, an arrival zone and outlet for molten metal; and an array of vertical baffles located between said arrival zone and the outlet, the baffles of the array being spaced apart transversely across the tundish to provide flow channels between the baffles;
said array of baffles being in the form of a unitary body of extruded tubular or cellular form extending from the floor of the tundish.
a floor and sidewalls, an arrival zone and outlet for molten metal; and an array of vertical baffles located between said arrival zone and the outlet, the baffles of the array being spaced apart transversely across the tundish to provide flow channels between the baffles;
said array of baffles being in the form of a unitary body of extruded tubular or cellular form extending from the floor of the tundish.
21. A tundish comprising:
a floor and sidewalls, an arrival zone and outlet for molten metal; and an array of vertical baffles located between said arrival zone and said outlet, the baffles of the array being spaced apart transversely across the tundish to provide restricted flow channels between the baffles, and comprising means for increasing the velocity of molten metal flowing therepast and therebetween.
a floor and sidewalls, an arrival zone and outlet for molten metal; and an array of vertical baffles located between said arrival zone and said outlet, the baffles of the array being spaced apart transversely across the tundish to provide restricted flow channels between the baffles, and comprising means for increasing the velocity of molten metal flowing therepast and therebetween.
22. A tundish according to claim 21, in which the baffles are of a high alumina ceramic material containing refractory particulates bonded by refractory cement.
23. A tundish according to claim 21 in which immediately on the downstream side of the array of baffles is a dam extending transversely across the floor of the tundish for at least a substantial portion of its width.
24. A tundish according to claim 21, in which the baffles are flat tiles which are parallel to each other.
25. A tundish according to claim 21, in which the baffles are tiles which are equidistant from each other.
26. A tundish according to claim 21, which contains at least one further baffle, dam or weir downstream from the array of baffles.
27. A method of purifying metal in a tundish comprising passing said metal in molten form between a zone of arrival and an outlet and past baffles located between said zone of arrival and the outlet, in which the metal is passed past and between an array of said baffles, the baffles of the array extending vertically and being spaced apart transversely across the tundish whereby flow of the molten metal is restricted to channels between the baffles and wherein the baffles are flat tiles, whereby removal of inclusions in the molten metal is enhanced.
28. A method according to claim 27, in which the tiles are positioned parallel to each other.
29. A method according to claim 27, in which the tiles are equidistant from each other.
30. A method of purifying metal in a tundish comprising passing said metal in molten form between a zone of arrival and an outlet and past baffles located between said zone of arrival and the outlet, in which the metal is passed past and between an array of said baffles, the baffles of the array extending vertically and being spaced apart transversely across the tundish whereby flow of the molten metal is restricted to channels between the baffles and wherein the array of baffles is in the form of a unitary body of extruded tubular or cellular form extending from the floor of the tundish to the surface of any molten metal contained therein, whereby removal of inclusions in the molten metal is enhanced.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8829918 | 1988-12-22 | ||
| GB888829918A GB8829918D0 (en) | 1988-12-22 | 1988-12-22 | Purifying steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2006351A1 CA2006351A1 (en) | 1990-06-22 |
| CA2006351C true CA2006351C (en) | 1995-09-26 |
Family
ID=10648933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2006351 Expired - Fee Related CA2006351C (en) | 1988-12-22 | 1989-12-21 | Purifying molten metal |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2006351C (en) |
| GB (1) | GB8829918D0 (en) |
| ZA (1) | ZA899516B (en) |
-
1988
- 1988-12-22 GB GB888829918A patent/GB8829918D0/en active Pending
-
1989
- 1989-12-13 ZA ZA899516A patent/ZA899516B/en unknown
- 1989-12-21 CA CA 2006351 patent/CA2006351C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2006351A1 (en) | 1990-06-22 |
| ZA899516B (en) | 1991-03-27 |
| GB8829918D0 (en) | 1989-02-15 |
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