The present invention relates to the field of devices used for conveying, containing, or filtering molten metals, such as aluminum. More particularly, it concerns a receptacle and an assembly for maintaining the temperature of the molten metal during handling. The present invention also relates to a casting assembly for casting the refractory of the receptacle or assembly, and to a manufacturing method.
In the metal industry, such as the aluminum industry, liquid metal is transferred from a location to another using heated trough or launder having a general U-shape cross-section, and including a castable refractory. An example of a prior art launder section 1 is shown in
Examples of such installations are described in patent applications WO 2004/082867 and US 2010/0109210 pertaining to the Applicant. While efficient, one drawback of the side-mounted heating troughs is that they are subject to infiltrations of liquid metal. In addition, their maintenance and replacement can be difficult. Heated covers are subject to metal splashing and mechanical abuse, shortening their useful life. Existing heated covers or side-mounted heating panels also tend to be rather cumbersome and expensive.
In light of the above, there is a need for improved devices that allow to maintain molten metal in a liquid state, and that also allow to be operated, maintained, and/or replaced in a simpler fashion. It would also be desirable if such devices or method had a lower cost than existing devices while remaining relatively easy to manufacture.
A receptacle for handling molten metal is provided. The receptacle has bottom and side walls which comprise a refractory. The refractory defines a cavity within which the molten metal is conveyed or contained. The receptacle comprises at least one channel extending within at least one of the walls. The channel has an inlet and an outlet. The inlet is connectable to a source for circulating a fluid within the channel. The outlet allows the fluid to be expelled from the channel. The channel allows, when the fluid is circulated therethrough, to regulate the temperature of the refractory and thereby of the metal conveyed or contained.
In an embodiment, the receptacle is for a launder section. The side walls comprise two opposed side walls, the two opposed side walls and the bottom wall provide the receptacle with a U-shape with two opened extremities. Each side wall has an inner surface facing toward the cavity, an opposed outer surface, a top surface and opposed end surfaces at the opened extremities.
In an embodiment, the receptacle for a filter box and comprises two pairs of opposed side walls, each side wall has an inner surface facing toward the cavity, and an opposed outer surface (20).
In an embodiment, an assembly is provided, which includes the receptacle and the source for circulating the fluid within the at least one channel.
In an embodiment, an assembly is provided, which includes the receptacle and a deflector connected to the outlet of the at least one channel, for directing the expelled fluid toward the refractory.
A casting assembly for casting the refractory is also provided. The casting assembly comprises a core for forming the at least one channel and a mold having a hollow shape.
A method for casting the refractory is also provided. The method comprises the steps of:
Advantageously, the receptacle can be heated by blowing a fluid (heated, ambient or cooled air, gas or liquid) which heats, maintains or cools the entire receptacle (or refractory), so that, when in use, the refractory in turns regulate the temperature of the molten liquid conveyed, contained or filtered. The receptacle and resulting assemblies are simpler and less cumbersome than existing solutions, yet they allow maintaining the molten metal in a liquid state, at a desired temperature. The manufacturing of the refractory remains relatively easy. Launders and filter box made with the receptacle of the present invention are also easy to install, operate, maintain and replace.
Other objects, advantages, and features of the present invention will become more apparent upon reading the following non-restrictive description of preferred embodiments thereof, given for the purpose of exemplification only, with reference to the accompanying drawings in which:
In the following description, similar features in the drawings have been given similar reference numerals. For the sake of clarity, certain reference numerals have been omitted from the figures when they have already been identified in a preceding figure.
Generally speaking, the present invention consists in providing at least one channel within a receptacle for conveying or containing molten metal, the receptacle including a refractory.
By refractory, it is understood to mean a composition that can be shaped or molded and then subsequently heated, fired, or calcined at a suitable temperature resulting in a hard, tough ceramic-like structure. Highly conductive refractory material such as silicon-carbide based, silica containing silicon carbide or alumina or a composition of these compounds can be used.
The channel(s) allow(s) blowing or pushing a fluid through it, which by conduction and/or convection will regulate the temperature of the refractory. The fluid pushed within the channel can be heated, cooled or at ambient temperature. Such receptacle is advantageously less subject to infiltrations of liquid metal. While the casting of the refractory may be slightly more complex than that for existing refractory bodies, the overall resulting receptacle and/or assembly, may it be the section of a trough, a launder, or a filter box, is likely to be easier to install, operate, maintain, and replace. The fluid source can advantageously be located outside or away from the portion of the receptacle conveying or containing the molten metal, and there are no mobile parts or electrical contraption likely to be in contact with the liquid metal.
Referring to
The receptacle 10 has two channels 22a, 22b extending within its respective walls 16a, 16b. The channels extend longitudinally within the side walls 16a, 16b. Of course, it can be considered to have a channel 20 extending transversally instead. Alternatively, it can also be considered to place a channel within the bottom wall 14 as well, or in replacement of the ones within the side walls 16a, 16b.
The channels 22a, 22b have an elongated cross-section, but of course, other shapes and configuration for the channels can be considered. For example, the wall defining a channel can be provided with ribs, riblets and/or grooves, for increasing the thermal exchange surface. Providing the refractory with long and narrow channel(s) advantageously allows increasing the transfer surface between the channel and the refractory, in turn increasing the transfer of heat from the fluid to the refractory.
In this preferred embodiment, the receptacle 10 is provided with a plurality of rods 25 extending transversally within the channels. The rods 25 help maintaining structural integrity of the refractory 12. The rods 25 also promote turbulence within the channels when fluid is circulated, for improving thermal exchanges with the body of the refractory. In the present case, the rods 25 are formed of the refractory material 12, during the casting process, as will be explained in more detail later on in the description.
Each channel 22a, 22b has an inlet 24a, 24b and an outlet 24a, 24b. The inlets 24a, 24b are connectable to a source for circulating a fluid, such as heated air, within the channels. The outlet 26a, 26b allow the fluid to be expelled from the channels. When the fluid is circulated within the channels, it modifies, regulates or maintains the temperature of the refractory 12 and, as a consequence, of the metal conveyed or contained within the receptacle. For example, heated air can be circulated within the channels, to increase the temperature of the refractory, such that when molten metal is circulated in it, the temperature of the metal is maintained. Alternatively, cooled or air at ambient temperature can be circulated within the channels, to cool down the refractory and at the same time, the molten metal handled in the receptacle.
In the present case, the refractory is a calcined castable refractory for use as part of a launder or trough, for conveying liquid metal. The receptacle 10 has a U-shape cross-section and two opened extremities 34a, 34b. Each side wall 16a, 16b has an inner surface 18 facing toward the cavity, an opposed outer surface 20, a top surface 32 and opposed end surfaces 28, 30 at the opened extremities 34a, 34b. The inner surface 18 defines the cavity 17 in which the molten metal is to be conveyed or contained, and the inlets 24a, 24b and outlets 26a, 26b open near the outer extremities 34a, 34b, either on the end or outer surfaces 20, 28, 30 of the refractory 12.
Still referring to
Now referring to
Referring to
Referring now to
The receptacle 10 has a first longitudinal collecting channel (27a) extending within the side wall (16a ), which connects to the inlet (24), and a second longitudinal collecting channel (27b) extending along another the side walls 27b, connected to the outlet 26. In the present case, the inlet has the shape of a longitudinal slot extending near the top end of the wall 16a.
Turning now to
The assembly 38 is supported by a structure (52) for supporting the launder sections 10i, 10ii, 10iii.
The assembly 38 preferably include channel sealing elements for sealingly connecting the channels of adjacent sections, such as RFM® bushings or the like. Optionally, access openings 64 are provided in the assembly, the openings 64 being located so as to face the connected extremities of the launder sections 10i, 10ii, 10iii, for facilitating maintenance or replacement operations.
Referring to
The receptacles 10i, 10ii of the assembly 39 are used in combination with deflectors 58, connected to the respective outlets 26 of the channels 22, for redirecting the expelled fluid toward the refractory 12 or elsewhere. Of course, it can be considered to provide only one of the receptacles with a deflector. The deflector 58 can take different shapes and form, but is preferably a tube. The tube can be made of one or several articulated segments.
The assembly can include the source 62 for circulating the fluid within the channel(s). The source can include an air blower, a heating element or a refrigerating or a combination of these elements. Alternatively, or in combination with an air blower, a heating or refrigerating element can be placed within the channel of the receptacle(s). The blower can be integrated with the heat source, or separated from it. An heat source 62 used for providing heated fluid can be for example a Leister or Farnham air heater of 15 kW coupled to a blower having a capacity of 1200 L/min, generating a source of hot air, having a temperature of around 900° C.
Referring to
Side wall 16b is provided with a U-shape inlet or entry 42 connectable to a launder or trough, by which molten metal is received. Side wall 16d is provided with an outlet or exit 44 by which filtered aluminum can be discharged. Sidewall 16a is provided with a drain 46. Filter boxes, similar to launders or troughs, also need to be heated in order to maintain the molten metal at a proper temperature. Providing channels within the side walls 16a, 16c, and bottom wall 14 allows not only to keep the refractory material at a proper temperature, but also to avoid having to provide the filter box with a cover provided with cumbersome electrical heating circuits as currently existing in the art.
Referring to
Referring to
Now turning to
The mold 74 has a hollow shape, and includes openings for receiving respective ends of the core 72. The openings can allow the creation of the inlet 24 and outlet 26 of the channel 22, or can be used for retaining the core in place within the mold.
As shown in
With reference to
The present invention also concerns a method for forming a refractory receptacle as described in the preceding figures. The method consists of providing a casting assembly comprised of at least a mold and a core for forming the channel. The core is inserted in the mold prior to pouring the refractory material such that the ends of the core exit through their respective openings of the mold. Preferably, the mold is placed upside down such that its openings are facing the ground. A castable composition of precursors of a refractory material is poured into the mold. The composition is left to rest until it sets, and it can then be unmolded. The composition can be left to rest for another predetermined period, such as 24 hours. This composition then is heated until the refractory material is obtained. Heat used for this process will result in burning the core, if made of wood. Other materials can be used for the core, such as polymeric core, and they can be removed from the refractory by being dissolved by an acid or similar substance.
As it can be appreciated, the receptacle, the casting assembly, and the manufacturing method of the present invention advantageously allow, by the use of channel(s) within the walls of the receptacle, to regulate the temperature of the refractory sufficiently, such as to maintain the molten metal conveyed, contained, or filtered in/through the receptacle in a liquid state.
This is a nonprovisional patent application of U.S. Provisional Patent Application No. 61/659,624, filed Jun. 14, 2012, and titled Receptacle for Handling Molten Metal, Casting Assembly and Manufacturing Method, which is incorporated herein by reference
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4508323 | Fleming | Apr 1985 | A |
20100109210 | Vincent | May 2010 | A1 |
20110140318 | Reeves et al. | Jun 2011 | A1 |
Number | Date | Country |
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1194695 | Oct 1985 | CA |
0581516 | Feb 1994 | EP |
0926248 | Jun 1999 | EP |
2004082867 | Sep 2004 | WO |
Number | Date | Country | |
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20130334744 A1 | Dec 2013 | US |
Number | Date | Country | |
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61659624 | Jun 2012 | US |