Metallurgical apparatus – Process
Reexamination Certificate
1999-03-30
2001-04-17
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
C266S901000, C266S216000, C075S687000
Reexamination Certificate
active
06217823
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a scrap submergence system of the type typically employed in metal recycling processes, particularly, the recycling of aluminum. In the recycling of metals, it is necessary to melt scrap pieces for treatment and processing. A large portion of the aluminum scrap pieces are thin walled as a result of the mechanical shaping action from which they are formed, such as, shaving, boring and cold rolling. Melting thin walled scrap pieces is particularly difficult because, (i) extended exposure to the hostile atmosphere in a traditional melting furnace results in extremely high oxidation loss and, (ii) rapid submerging in molten metal is severely hampered by the fact that thin walled scrap pieces float on molten metal (“floating scrap”).
In a typical melting operation used to convert floating scrap to ingot, a melting furnace is provided with an enclosed hearth and a connected open sidewell. Usually the sidewell is divided into a pump well and a melting bay. A pump or other molten metal flow inducing apparatus is positioned externally to the melting bay (e.g., in the pump well), and causes molten metal to flow from the hearth to the melting bay. Typically the melting bay is further divided into a chargewell and a drosswell. Metal scrap pieces are fed into the melting bay, particularly the chargewell component thereof.
A variety of apparatus have been used in the melting bay (specifically in the chargewell) to facilitate the submergence of the scrap metal below the surface of the molten metal bath. Three major types of systems exist. The first type includes mechanical systems constructed primarily of a rotor which creates a molten metal flow from the top surface. Examples of these devices are shown in U.S. Pat. Nos. 3,873,305; 3,997,336; 4,128,415; and 4,930,986. The second type of system uses a mechanical device to physically push the scrap below the melt surface (elephant feet/well-walkers). The third type of system relies on the shape of the chamber without rotation of a rotor to create a metal flow which submerges scrap pieces in the chargewell. Particularly, the flow of molten metal into the chargewell is manipulated in such a manner to achieve a vortex which draws chips from the top surface into the bath. These systems include, for example, U.S. Pat. Nos. 3,955,970; 3,984,234; 4,286,985; and U.S. Ser. No. 08/784,832, each of which is herein incorporated by reference. The present invention is directed to this third type of scrap submergence system. However, the present invention is directed to a novel system which achieves a high charge rate and a high recovery rate with minimal maintenance requirements (three important requirements).
While the present invention is directed to the third class of submergence devices, the present invention contrasts the traditional design by achieving a vortex with an initially upward flow of metal adjacent the outer walls of the feed bay. In contrast, in U.S. Pat. No. 4,286,985, a chargewell includes a top inlet and a bottom outlet which are positioned to create a downward flow of molten metal adjacent the side walls of the well to form a vortex. Similarly, with reference to U.S. Ser. No. 08/784,832, a chargewell is designed to include a unique wedge positioned on one of the walls of the feed bay to create a downward flow of molten metal and the vortex. In both systems, the intention of the design is to create a downward flow in the molten metal pattern as it circles to form the vortex pattern within the charge well.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of this invention to provide a new and improved metal scrap submergence device.
It is an advantage of this invention to provide a new and improved scrap submergence system that can function without mechanically moving components.
A still further advantage of this invention is to provide a new and improved metal scrap submergence device that improves the efficiency of scrap submergence.
Another advantage of this invention is to provide a new and improved scrap submergence device that is effective with floating scrap pieces.
A further advantage of the invention is associated with the use of an easy to manufacture body without moving parts—which provides longevity. In addition, the invention is easy to maintain/clean and minimizes the required working depth of molten metal.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing objects and in accordance with the purpose of the invention as embodied and broadly described herein, the scrap submergence device of this invention comprises an open top chamber including walls constructed of a heat resistant material. The chamber includes an inlet positioned in a side wall and an outlet positioned in its base. Generally, the chamber can be described as a bottom inlet, bottom outlet arrangement. A ramp is formed adjacent the walls of the chamber, spiraling upwardly thereon.
Preferably, the metal scrap submergence device will be constructed in a manner which positions the bottom edge of the ramp on the base of the chamber adjacent the inlet. In a particularly preferred form of the invention, the ramp will spiral through at least 180°, and preferably 270°, of the chamber circumference. In a particularly preferred form of the invention, the ramp will include a portion having a slope of about 5°, and preferably 10° to 15°. However, it should be understood that the slope can vary throughout the dimensions of the ramp. In fact, the geometry of the preferred embodiment (cylindrical) is such that the outer edge of the ramp adjacent the wall and inner edge of the ramp have the same rise, but cover slightly different distance. Hence, the outer edge and the inner edge of the ramp will exhibit correspondingly different slopes—the outer edge being somewhat less than the inner edge. Accordingly, reference herein to slope can refer to the lesser point along the outer edge.
In a further preferred embodiment of the invention, a wall will extend from the inner edge of the ramp, helping to define an entrance to the outlet. Preferably, the top edge of the wall will be at approximately the same height as the terminal edge of the ramp.
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van Linden Jan H. L.
Vild Chris T.
Fay, Sharpe, Fagan, Minnich & McKee, LP
Kastler Scott
Metaullics Systems Co., L.P.
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