Vortex well inerting

Abstract

A method of providing an inerting atmosphere to the surface of molten aluminum in a vortex charge well of a reverberatory melting furnace is provided. The purpose is to improve aluminum recovery (reduce aluminum oxidation melt loss) by displacing the ambient atmosphere above the molten vortex with an inert gas. The method includes introducing a flow of an inerting gas into an inerting region immediately above the surface of the vortex charge well. The inerting gas may be selected from the group consisting of nitrogen, argon, or a mixture thereof. The inerting gas may be introduced into the charge inlet chute, through a diffuser, or a ring manifold. The vortex charge well may include a lid.

Claims

1. A method of providing an inerting atmosphere to the surface of molten aluminum in a vortex charge well of a reverberatory melting furnace, the method comprising: introducing a flow of an inerting gas into an inerting region immediately above the surface of the vortex charge well.

2. The method of claim 1, wherein the inerting gas is selected from the group consisting of nitrogen, argon, or a mixture thereof.

3. The method of claim 1, wherein the inerting gas is introduced into the inerting region through a diffuser.

4. The method of claim 3, wherein the diffuser is positioned proximate to the surface of the vortex charge well.

5. The method of claim 1, wherein the vortex charge well further comprises a lid.

6. The method of claim 1, wherein the inerting gas is introduced into the inerting region thorough a ring manifold.

7. The method of claim 6, wherein vortex charge well comprises a vortex headspace comprising a top circumference, and wherein the ring manifold is positioned near the top circumference of the vortex headspace.

8. The method of claim 1, wherein the inerting gas is introduced into the inerting region thorough a partial ring manifold.

9. The method of claim 8, wherein vortex charge well comprises a vortex headspace comprising a top circumference, and wherein the ring manifold is positioned near the top circumference of the vortex headspace.

10. The method of claim 1, wherein the inerting gas is introduced into the inerting region through both a diffuser and a ring manifold.

11. The method of claim 6, wherein the vortex charge well further comprises a lid.

12. A method of providing an inerting atmosphere to the surface of molten aluminum in a vortex charge well of a reverberatory melting furnace, the method comprising: introducing a flow of an inerting gas into a charge inlet chute, whereby the inerting gas travels with a stream of aluminum charge pieces and into an inerting region immediately above the surface of the vortex charge well.

13. The method of claim 12, wherein the inerting gas is selected from the group consisting of nitrogen, argon, or a mixture thereof.

14. The method of claim 12, wherein the charge inlet chute further comprises a lid.

15. The method of claim 12, wherein the vortex charge well further comprises a lid.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

(2) FIG. 1 is a schematic representation (top view) of a side well-charged aluminium melting furnace with a vortex charge well.

(3) FIG. 2 is a schematic representation (end view . . . view AA) of a side well-charged aluminium melting furnace with a vortex charge well.

(4) FIG. 3 is a schematic representation (end view . . . view AA) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with a inert gas diffuser, in accordance with one embodiment of the present invention.

(5) FIG. 4 is a schematic representation (side view . . . view BB) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with a inert gas diffuser, in accordance with one embodiment of the present invention.

(6) FIG. 5 is a schematic representation (end view . . . view AA) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with a inert gas ring manifold, in accordance with one embodiment of the present invention.

(7) FIG. 6 is a schematic representation (top view) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with a inert gas ring manifold, in accordance with one embodiment of the present invention.

(8) FIG. 7 is a schematic representation (side view . . . view BB) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with the inert gas introduced with the charge, in accordance with one embodiment of the present invention.

(9) FIG. 8 is a schematic representation (side view . . . view BB) identical to FIG. 7, except illustrating optional lids on the charge chute and/or the vortex well, in accordance with one embodiment of the present invention.

(10) FIG. 9 is a schematic representation ((end view . . . view AA) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with the inert gas introduced with the charge, in accordance with one embodiment of the present invention.

(11) FIG. 10 is a schematic representation (end view . . . view AA) identical to FIG. 9, except illustrating optional lids on the charge chute, in accordance with one embodiment of the present invention.

(12) FIG. 11 is a schematic representation ((end view . . . view AA) of a side well-charged aluminium melting furnace with a vortex charge well, focusing on the vortex well, with the inert gas introduced with the charge through a diffuser, in accordance with one embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

(13) Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

(14) It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure

(15) FIGS. 3 and 4 show an embodiment for gas inerting the area 104 immediately above the vortex charge well 101. Gaseous nitrogen or argon 105 can be injected through a single diffuser 106, to disperse the inert gas 105 in a low velocity, uniform and non-turbulent manner. It is advantageous to inject this inert gas 105 as low as practically possible, near the bottom of the V-shaped vortex, since the gas will become heated and rise, and if starting low near the molten vortex surface it can act to push away or displace ambient air. High inert gas velocity or turbulence is not desired, since higher inert gas velocities can tend to infiltrate ambient air, and higher gas velocities could cause turbulence to agitate the molten metal surface. Uniform distribution of the inert gas (nitrogen or argon) is best, to spread in all directions so as to cover the entire V-shaped vortex, at low velocity to minimize turbulence.

(16) A lid 107 can be utilized to improve the gas surface inerting effect. Since the inert gas 104 will become heated and rise away from the vortex surface, a lid 107 can help to contain the inert gas over the molten vortex. Ideally a slightly positive pressure can be formed under the lid 107, within the vortex surface headspace 108, to more effectively push ambient air (21% O2) away from the vortex surface and maintain the inert gas 104 cover. The lid 107 will be positioned to allow the gases to escape through a relatively small channel(s) 109, to maintain the desired atmosphere within the vortex head space 108.

(17) As discussed above, while these vortex charge wells improve aluminum recovery by more quickly and effectively submerging the light gauge solid aluminum charge pieces 110, they also contribute to some additional aluminum oxidation by virtue of their configuration. In order to create the molten aluminum vortex shape, molten aluminum is continuously exposed and re-exposed to the ambient atmosphere. The present invention reduces or eliminates this exposure to the ambient atmosphere by forming the gas inerting area 104, directly above the surface of the vortex.

(18) As shown in FIGS. 5 and 6, in another embodiment it is advantageous to utilize a ring-manifold 111, or partial-ring manifold (not shown), mounted near the top circumference of the vortex head space 108, to direct the inert gas 104 downward along the surface of the vortex. This ring manifold 111 could be used alone, or in combination with a single center diffuser (not shown), and either with or without a lid 107.

(19) It is estimated that the required flow rate of nitrogen or argon will be roughly 20 SCFM, for a vortex bowl of roughly 48 ID; flow rates can be adjusted for varying sizes and varying configurations, and to achieve the desired results. It is expected that the value of the improved aluminum yield (reduced aluminum melt loss) will significantly exceed the cost of the inert gas required (nitrogen or argon); this can be measured at any particular site by conducting a relatively short term trial or test.

(20) FIGS. 7-11 show an embodiment for gas inerting the area 104 immediately above the vortex charge well 101. Gaseous nitrogen or argon 105 can be injected through an orifice 112, or a diffuser 106, to disperse the inert gas 105 in a low velocity, uniform and non-turbulent manner into the charge inlet chute 113. The inert gas 105 will be carried along with the incoming, finely divided charge material 110, especially in cases where the charged materials 110 are conveyed through an enclosed chute 114, or a partially enclosed U-shaped chute 113.

(21) Some air can be entrained with the incoming finely divided charge materials 110, such as machine chips or shreds, which can have a void fraction when loosely packed, which is how they are typically conveyed in these charging mechanisms. In certain cases, including inert gas with the incoming charge materials 110 may improve the inerting effect, by displacing ambient air that can be entrained within the loosely packed, finely-divided incoming charge materials.

(22) A lid 107 can be utilized to improve the gas surface inerting effect. Since the inert gas 104 will become heated and rise away from the vortex surface, a lid 107 can help to contain the inert gas over the molten vortex. Ideally a slightly positive pressure can be formed under the lid 107, within the vortex surface headspace 108, to more effectively push ambient air (21% 02) away from the vortex surface and maintain the inert gas 104 cover. The lid 107 will be positioned to allow the gases to escape through a relatively small channel(s) 109, to maintain the desired atmosphere within the vortex head space 108.

(23) The skilled artisan will recognize that these embodiments may be combined as desired.

(24) It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.