JPS6314055B2 - - Google Patents

Description

Claim 1: It has a closed heating tank and an open tank in which scrap is charged into the molten metal and transported by the action of a molten metal circulator, and a partition is provided between the closed heating tank and the open tank, and the partition wall is integral with a wall section extending into the open tank, said partition wall being provided with two openings, one of the openings being on one side of said wall section, and a molten metal circulator on one side of said wall section; In a method of melting metal scrap in a recirculating device provided, the scrap is fed into an open tank near the molten metal circulator to begin melting the scrap in the molten metal, and at the same time as the scrap is melted, the closed heating tank is molten metal is continuously circulated from the closed heating tank into the open tank by drawing the molten metal through an opening in the wall immediately adjacent to the molten metal circulator; Scrap melting and withdrawal is conducted directly by a molten metal circulator having spaced apart bottom and top plates, the top plate having a centrally located circular aperture, and the bottom plate being aligned with the central axis of the circular aperture in the top plate. A frusto-conical boss having a concentric center axis is integrally fixedly disposed in the center, and the drive shaft is fixedly attached to the boss, and the boss and the bottom plate are fixedly arranged in a radial direction along the entire radial length. the circular opening in the center of the top plate has an inner diameter larger than the diameter of the frusto-conical boss, the vane is secured to the top plate at the end, and the drive shaft is connected to the circulatory blade and the frusto-conical boss. The shaped boss rotates the molten metal together with the top and bottom plates, and the gentle vortex in the molten metal transports the scrap into the central opening of the top plate and fills the void between the top and bottom plates. The molten metal is pumped vertically downwardly through the molten metal circulator to draw molten metal from the closed heating tank into the open tank and from the open tank into the closed heating tank through the opening remote from the molten metal circulator. A method of melting metal scrap produced in

2. A closed heating tank, an open tank charged with molten metal at a predetermined height, which is integral with a wall portion that separates the closed heating tank from the open tank and extends into the open tank, and one of the two openings is connected to the wall. partitions located on either side of the section and always below the surface of the molten metal; submerged in the molten metal and located on one side of the wall section below the opening in the partition; molten metal circulator,
in the openings near the submerged molten metal circulator for circulating molten metal from the closed heating tank to the open tank by drawing the molten metal from the closed heating tank through the opening in the bulkhead immediately adjacent to the molten metal circulator. the molten metal circulator has a spaced-apart bottom plate and a top plate, the top plate being centrally located; the bottom plate has a truncated conical boss integrally fixed at the bottom, the truncated conical boss has a central axis concentric with the central axis of the top plate circular opening; a drive shaft is secured and a radially extending vane is secured to the boss along the entire radial length relative to the bottom plate, the central opening in the top plate having an inner diameter greater than the diameter of the frusto-conical boss; The vanes are fixed at their ends to the top plate, and the drive shaft is an arrangement consisting of a circulator vane, a frusto-conical boss, and a non-self-submersible piece adapted to rotate the molten metal together with the top and bottom plates. A recirculation device that submerges and conveys the contents into molten metal.

TECHNICAL FIELD This invention relates to an improved method and apparatus for submerging, transporting, melting and recycling metal charges in a melting medium.

BACKGROUND OF THE INVENTION In the recycling of scrap aluminum having a large surface area to volume ratio, the scrap becomes suspended on the surface of the molten aluminum. The presence of scrap that resists settling poses major and minor inconveniences to aluminum reprocessing equipment. Large manufacturers with limited financial resources to invest in improved aluminum reprocessing processes have increasingly complex feed systems for pumping molten aluminum through the heating and melt phase of the reprocessing equipment. Such a supply device appears in a simple drawing with a functional design sense. It is very important to construct a pump of refractory material that is precisely constructed to cooperate with specially shaped walls surrounding the pump impeller or forming a volume through which the scrap along with the molten metal is conveyed to the pump. It is said that it can be expensive. The walls surrounding and housing the pump are made of refractory material. The fabrication, formation and maintenance of such walls is quite expensive. In management, it should be noted that as long as the material charged into the furnace is handled roughly, the environment in the factory where the regeneration is carried out will not be improved. Loading the processing equipment and subsequent cleaning can cause damage to the walls. . This damage is particularly expensive to replace when it involves precisely constructed walls at the pump. This expensive arrangement and the replacement just described are not cost effective for small volume reprocessing operations.

If non-aluminum scrap, such as steel, is inadvertently included in the scrap charged to the processing equipment, problems such as pump clogging may occur.
The non-aluminum scrap becomes interposed between the pump impeller and a cooperating wall surrounding the pump impeller to stop the impeller. When such impeller stoppages occur, the walls and pump impellers are often damaged.

Examples of how technology has advanced in the design of pump impellers and surrounding walls of the type just described are provided by Van Linden, U.S. Pat. No. 3,997,336;
4128415, Claxton et al. U.S. Patent No. 3984234
can be found in the specification. These patents recognize and address the problem of sinking scrap that is essentially not self-sinking. Additionally, these patents acknowledge and attempt to address the problem of skim appearing on the surface of molten aluminum. The formation of skims in aluminum melt processing is particularly disadvantageous because the skim, which is primarily aluminum oxide, forms rapidly due to the highly reactive nature of aluminum and the atmosphere accentuated by the presence of hot molten metal. That's a problem. The pump impeller in each of the above-mentioned US patents is located close to a wall that cooperates with the pump impeller to enhance the pumping action or to guide the molten aluminum carrying scrap to the pump. Problems such as clogging of the pump impeller and occurrence of skimming, which were also considered in the above-mentioned patents, were unavoidable. This actually occurs when pieces of non-melting material, such as refractory materials having the same specific gravity as aluminum, flow into the molten metal and are fed into the pumping section of the processing equipment.

DISCLOSURE OF THE INVENTION In particular, the present invention provides for submerging and conveying aluminum scrap consisting of non-self-sinking pieces;
It relates to a method and apparatus for melting and circulating. The melting apparatus of the present invention comprises a molten metal scrap conveying circulator submerged below the surface of the molten metal at a point below the surface of the molten metal. Means is provided for feeding and guiding the scrap into an open tank into which heated molten metal is drawn. The circulator continuously draws heated molten metal containing scrap into the circulator in which the scrap is completely entrained within the molten metal and then delivered to the molten metal circulation path. This molten metal circulation path delivers the scrap entrained into the molten metal to a circulator for subsequent heating, melting, and recirculation.

The present invention, which will be fully described below, completely eliminates the need for walls proximate to the impeller in the prior art and simultaneously provides for conveyance of scrap to molten metal with a simultaneous reduction in skim formation. .

The main object of the invention is therefore to provide an inexpensive method and apparatus for sinking, conveying, melting and circulating aluminum scrap which is characterized by its inability to self-sink. be.

Another object of the invention is to provide a molten metal circulator which cooperates with the molten metal medium to draw non-self-sedimenting scrap into the molten metal and into melting conditions.

Another object of the present invention is to provide a fluid flow path in the molten metal medium that cooperates with the molten metal medium and a vertical wall to provide a fluid flow path for moving the molten metal through the melting apparatus. An object of the present invention is to provide a melting apparatus equipped with a molten metal circulator for forming a molten metal.

Yet another object of the invention is to provide a furnace and molten metal holding tank that is simple in construction and easy to clean and maintain.

Other objects and advantages of the present invention will become apparent from the detailed description below, taken in conjunction with the accompanying drawings.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a recirculating scrap melting apparatus embodying the present invention, FIG. 2 is a plan view of the melting apparatus in a preferred embodiment of the invention, and FIG. The cross-sectional view, Figure 4, is 4- in Figure 2.
5 is a perspective view of the molten metal scrap conveying circulator, and FIG. 6 is a sectional view taken along line 4, 6-6 in FIG.
7 is a plan view of a furnace, a maintenance tank, and a molten medium circulation device embodying the present invention; FIG. 8 is a sectional view taken along line 8-8 in FIG. 7; FIG. 7 is a sectional view taken along line 9-9 in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown in block diagram form a recirculating scrap melting apparatus embodying the present invention. The recirculating scrap melting apparatus has a closed heating tank 11 and an open tank 12. Scrap and flux are introduced into the open tank 12. A scrap conveying molten metal circulator, which will be described in more detail later, is provided in the open tank 12 from the closed heating tank 11 to the open tank 12 as indicated by the arrow 13.
to circulate molten metal within. The molten metal is then transferred to a closed heating tank 1 as indicated by arrow 14.
It is circulated within 2. Scrap and flux are introduced into one end of open tank 12 as shown by arrow 16 and skim is removed from the opposite end of open tank 12 as shown by arrow 17. The final product of the recirculating scrap melter is skimless molten aluminum discharged from closed heating vessel 11 as indicated by arrow 15.

Referring now to FIGS. 2 and 3, there are shown top and front views detailing a preferred embodiment of the invention.

The following description will simultaneously describe the melting apparatus of FIGS. 2 and 3. Figure 2 shows a closed heating tank 11 and an open heating tank 1.
2 is shown. The closed heating tank 11 and its detailed structure are conventional in that a cover 18 is provided on the closed heating tank 11. The closed tank 11 and the open tank 12 are made of refractory material. As clearly shown in FIG. 3, the refractory material is covered with a metal coating 19. metal coating 1
9 is heat-resistant steel. A pair of burners 21, 21a are shown facing downward within the heating tank 11. The nature and operation of the burners 21, 21a are the same as those used today by those skilled in the art. Only two burners are shown. It should be understood that the location and number of burners is a matter of design based on the nature of the fuel used in the combustion process and the types of burners available. Closed heated tank 11 and open tank 12 are shown filled with molten metal medium 20, which in the preferred embodiment is aluminum.

The open tank 12 has a wall portion 22 made of fireproof material.
is provided, and this wall portion 22 is integrally connected to a partition wall 23 extending in the longitudinal direction of the closed heating tank 11 and the open tank 12. The open tank 12 has an end wall 24 and a front wall 27. The closed heating tank 11 has a rear wall 28.

The partition wall 23 has two openings 29 and 31. The location of the septum 23 and openings 29, 31 is important to the operation of the recirculating scrap melter and the method encompassing this invention. The molten metal scrap transport circulator 32 is connected to a motor 34 by a drive shaft 33. Motor 34 may be an electric motor with selectable speeds or any other suitable motor. It can be seen that the circulator 32 is provided intermediate between the wall section 22 and the end wall 26. In addition, the opening 31 is also connected to the circulatory system 3.
2 and below the surface 35 of the molten metal medium 20 midway between the wall portion 22 and the end wall 26 . The relative positions of circulator 32, opening 31, and wall portion 22 provide optimal implementation of the method of the invention as shown. A circulator 32 driven by a motor 34 provides a fluid flow path for molten metal. This molten metal flow path, shown only by arrows, sucks molten metal through opening 31 and circulates the molten metal through open tank 12 and then through opening 29 and back into closed heating tank 11. Although not shown in the drawings, it will be appreciated that the surface of the molten metal within the closed heating vessel 11 is substantially free of skim. Of course, closed heating tank 1
There is a very thin layer of oxide film on the surface of the molten metal. It will be noted that all walls of the closed heating tank 11 and the open tank 12 are simple straight vertical walls made easily and inexpensively of refractory material. The term inexpensive is intended to be a relative term in view of the worst wall-shaped scrap recirculation devices available today as previously noted.
The dynamic operation of the molten metal scrap transport circulator 32 will now be described in detail. Opening 29 in partition wall 23
The lower side is the floor 36 of the closed heating tank 11 and the open tank 12.
installed so that it is at the same height as the The location of the opening 29 is a large and easily submerged scrap 37.
This is important in that it sinks to the bottom of the open tank 12 and is trapped in the molten metal fluid flow path created by the circulator 32, feeding the closed heated tank 11 where large chunks are melted. Practically speaking, scrap 3
7 sinks to the bottom and most of it is melted at this stationary position.

In FIG. 3, it can be easily seen that the scraps 37, 41 are fed into the open tank 12 at one end by conveyors 38, 39. As already noted, the scrap 37 on the conveyor 38 is large and tends to sink on its own due to its weight and shape.

However, the conveyor 39 conveys scrap 41 having a large surface area to volume ratio.
This cannot subside on its own. Segmented aluminum cans, whole cans, and small pieces collected during the manufacturing process are typical non-self-sinking scraps.

Non-self-sinking scrap to be placed into the molten metal 20 must overcome the surface tension of the layer of skim 40 formed over the molten metal 20.

The scrap 41 that cannot self-sink is the circulatory system 32.
A gentle vortex 42 created by Vigorous vortices should be avoided because when drawing non-self-sinking scrap into the molten metal, the surrounding atmosphere is also drawn into the vortex, greatly promoting the formation of skim, which is a very undesirable by-product. The gentle vortex 42 cooperates with the molten metal drawn through the opening 31 to cause the non-self-sinking scrap 41 to sink into the molten metal 20. The circulator 32, by the described dynamic action, carries the scrap 41 completely into the molten metal 20 and the scrap begins to melt. The circulator 32 supplies molten metal to the fluid flow path along with the entrained scrap. The scrap is then melted by the heat extracted from the subsequent molten metal medium in the flow path through the open tank 12 and becomes part of the circulating molten medium.

The closed heating tank 11 has an opening 30 in the rear wall 28 through which the skim free of molten aluminum is discharged. In FIG. 3 it can be seen that the opening 30 in the rear wall 28 is located at a point below the surface of the molten metal 20 so that the skim in the closed heating vessel 11 does not enter the final molten metal 15. Final molten metal 15
leaves the closed heating tank 11 through a specially formed opening 30 in an amount commensurate with the supply of solid scrap to the open tank 12.

The removal of skim and the supply of fluxing agent to the melting apparatus can be understood by the design of FIG. Flux feeder 44 is shown feeding fluxing agent to gentle vortex 42 as shown.

Skimming is accomplished as shown in FIG. 3 by providing an angled top surface 25 at the top of the end wall 24. As the skim 40 is formed and moved by the action of the moving molten metal 20, it becomes built up on the sloped top surface 25 for removal by hand or by automatic equipment not shown.

Referring to FIG. 4, the same reference numerals used in FIGS. 1 and 3 are used to represent the same parts. Molten metal scrap conveyor circulator 32
To facilitate the explanation of the dynamic action of the circulator 32 on the molten metal 20 such that the molten metal is drawn from the closed heating tank 11 through the opening 31 into the central portion 50 of the circulator 32. is shown in cross section. The fluid flow path of molten metal from closed heating vessel 11 is indicated by dotted arrows 51, 52.

The self-non-sinking scrap 41, which is shown entering the gentle vortex 42 from above, is caught in the reflux and sucked into the opening in the central part 50 of the circulator 32, where it is suspended in the moving molten metal. completely drawn in. The circulator 32 has vanes 53, 54 connected at their inner ends to a frusto-conical boss 47, shown in cross section. Scrap 41 drawn into the molten metal is forced outward by vanes 53,54. Details of the circulator 32 and its particular operation will be fully explained in the discussion of FIGS.

Reference will now be made to FIG. 5, which is a three-dimensional representation of the molten metal scrap conveying circulator 32. Circulatory system 3
2 is made of refractory material and constructed using conventional techniques. Circulator 32 has what may be referred to as a bottom plate 45 and a top plate 46. The bottom plate 45 and the top plate 46 are spaced apart as shown and have a plurality of radially extending vanes 53, 5 integrally secured thereto.
4, 55, 56, 57, and 58. A frustoconical boss 47 is integrally fixed to the center of the bottom plate 45. The drive shaft 33 is fixed to the truncated conical boss 47 by means not shown. The height of the boss 47 is lower than the distance between the bottom plate 45 and the top plate 46. Feathers 53, 54, 55, 5
6, 57, and 58 have inner ends in the radial direction fixed integrally to the boss 47 at a point on the outer surface of the boss 47 between the bottom plate 45 and the top plate 46 of the illustrated frustoconical boss 47. . Feathers 53, 54, 55, 56,
The bottom radially extending edges of the blades 57, 58 are fixed to the bottom plate 45, and the blades 53, 54, 55, 56,
The outer ends of 57 and 58 are secured to the top plate 46 as shown. The top plate 46 has a circular opening 48 in the center, and this opening 48 is coaxial with the axis of the drive shaft 33. It is important for the operation of the circulator 32 that the inner diameter of this central opening 48 is larger than the outer diameter of the base of the frusto-conical boss 47. Downwardly sloping sides 59, 60, 61, 62, 6 of vanes 53, 54, 55, 56, 57, 58 cooperating with frusto-conical boss 47 and bottom plate 45 and top plate 46
3,64 serves to create a wide suction section (shown in dotted lines) extending over and around the circulator 32. The strong fluid flow indicated by arrow 68 is such that the molten metal supplied from the closed heating tank 11 flows into the circulator 32 together with the self-sinking scrap as previously described.
The scrap is drawn in, where it is completely sucked in and forced outwardly towards the peripheral wall of the open tank 12 mentioned above.

Returning to FIG. 2, clockwise rotation of the circulator 32 causes the side portion 71 of the wall portion 22, the partition wall 23, the end wall 2
6. A radial outward flow can be seen as evidenced by the arrows 65, 66, 67, 68, 69, 70 to create a pressure build-up against the front wall 27. The only release of this pressure is through an opening formed between the end 72 of the wall section 22 and the front wall 27. A melting process that supplies scrap and molten metal conveyed through open tank 12 and then supplies molten metal based on the combination of newly melted scrap and surrounding molten metal via opening 29 and closed heating tank 11 to opening 31. There is a constant release of this pressure which achieves a strong fluid reflux through which the metal medium flows. At opening 31, circulator 32 draws molten metal into circulator 32 to begin the cycle again. It is important to note that the circulator 32 is spaced from the wall surrounding the circulator 32 to prevent large pieces of insoluble scrap from becoming stuck between the circulator 32 and the wall. Damage to the circulator 32 and the walls caused by blockages of this type are thus eliminated.

Referring now to FIG. 6, which shows a cross section of the circulatory system 32 of FIG. 5, it will be explained. As previously noted, insoluble scrap and pieces of refractory material may become mixed into the molten metal medium and come into contact with any equipment provided for flow through the melting equipment. .
In FIG. 6, an object 73 is shown stuck in the opening in the central section 50. Removing the object 73 is a simple matter, after stopping the motor, temporarily lifting the circulator 32 from the molten metal and removing the object 73 with scissors. If such a foreign object were to strike the top plate 46 without entering the central opening, the object would fall close to the circulator 32 between the circulator 32 and the spaced wall. Furthermore, it should be noted that the circulator 32 in FIG. 6 has a groove 47a formed in the bottom plate 45 as shown. This groove 47a
This prevents cracking due to different hardening rates of the refractory castings of different cross sections of the circulator 32.

The cross section of FIG. 6 clearly shows the flow paths 74, 74b, 74c of molten metal fluid flowing through the circulator 32.

Reference will now be made to FIG. 7, which shows a top view of a furnace, maintenance tank, and molten medium circulation system embodying the present invention. A description of the relationship of the molten metal or medium to the circulator and the manner in which the circulator preferably operates to accommodate and melt scrap has been provided above. Figures 7, 8 and 9 detail further features of the invention so that it finds utility in a complete system.

In particular, closed heating tank 75 and maintenance tank 85 are shown. The heating tank 75 and the maintenance tank 85 are connected to the front wall 7
6, a rear wall 77, a cover 78, a first end wall 79, a second end wall 80, and a floor 81. Cover 78 is not shown in FIG. The partition wall 82 separates the heating portion of the heating tank 75 from the maintenance portion of the maintenance tank 85. The partition wall 82 has a large number of passages 83, 84, 86, which are provided to communicate between the heating tank 75 and the maintenance tank 85.
87.

As best seen in FIG. 7, passages 83 and 84 allow the melting medium to freely flow from heating tank 75 to maintenance tank 85. As shown in FIGS. 7 and 8, passages 86a, 86, 87 allow combustion gases from oil or gas treaters 88, 89 to flow freely over the surface of the melting medium from heating tank 75 to maintenance tank 85. I try to keep it flowing. Combustion or flue gases are exhausted through chimney 91, as it is called.

The heating tank 75 is provided with a purification slope 92 and has a closure in the form of a guillotine-shaped door 93 at its upper end. The maintenance tank 85 has a purification slope 94 and a guillotine-shaped door 95.

In the front wall 76 there are openings 96, 97 through which the melting medium circulates by a schematically illustrated melting medium circulator 98. The circulator 98 is provided within the open tank 100. The open tank 100 has a scooping slope 101 and a wall 102 as shown.

An inlet 105 for molten metal or medium is in the seventh
Provided as shown in the figure. Rail 107,1
The injection port 105 for injecting into the furnace is arranged so that the molten metal train 106 supported by the molten metal train 106 can transport the molten metal, that is, the molten metal, in the next process. Out-of-furnace discharge inlets 109 for the heating tank and maintenance tank are provided as shown.

Containers 110, 111, 112 are connected to rails 113,
114.

When the guillotine-shaped door 93 is opened, the opening 9
6, 97 and passages 83, 84, 86, 87 are important for the location of the guillotine door 93 in this invention.

In view of the foregoing description, it is highly apparent that the melting apparatus and method of operating the melting apparatus of the present invention represents a distinct improvement over those previously available in a simpler and less expensive manner.

Although one embodiment of the invention has been illustrated and described,
It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the invention.