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Method of recycling brazing sheet

Inactive Publication Date: 2005-12-01
ARCONIC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a method for recycling metallic clad materials made of two or more different metals or metal alloys. The method involves heating the clad materials in a furnace to melt the metal with the lowest melting temperature, resulting in a first molten metal and a second unmelted metal. The scrap feedstock is agitated while heating to separate the molten metal from the unmelted metal, and the molten metal is removed from the furnace. The method allows for the separation and recycling of both clad and core metals without contamination. The technical effect of the invention is the efficient recycling of metallic clad materials based on their temperature differences."

Problems solved by technology

Because the scrap contains both aluminum alloys with a high Si content and aluminum alloys with a low Si content, simple melting of the scrap is inadequate for recycling the metal materials, because this would result in an combined aluminum alloy having a raised Si content, too high to be used for producing similar type metallic core alloys, unless diluted with substantial amounts of pure (prime) aluminum or alloys having a very low Si content.
In all of the above methods, the focus is on recovery of the core alloy only, and the methods do not attempt to minimize contamination and / or oxidation of the clad alloy.

Method used

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  • Method of recycling brazing sheet
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  • Method of recycling brazing sheet

Examples

Experimental program
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examples

[0033] The following examples are intended to illustrate the invention and should not be construed as limiting the invention in any way.

[0034] Dual-sided clad brazing sheet hot mill edge trim pieces of varying clad compositions and different clad thickness were loaded in a batch lab-scale unit that provided hot gas (air plus nitrogen) to heat the scrap to the target set point. When the scrap material achieved the preheat set point, the shaking mechanism (vibration) was started to separate the clad from the core. A perforated plate in the heating chamber allowed the melted clad to drain from the heating chamber into a collection pot, where it was allowed to cool. The efficiency of the separation was measured in terms of weight distribution and composition analysis of the core and clad fractions.

example # 1

Example #1

[0035] Hot mill trim scrap was preheated, using the method of the present invention, to 1000° F. and agitation started. When the scrap achieved the target set point of 1160° F. a five-minute countdown was started. An analysis of the weight distribution and composition of separated core and clad materials is shown in Tables 1 and 2.

TABLE 1EXAMPLE #1 WEIGHT SEPARATIONRecoveredRecoveredCORECLADPercentPercentActualActualSeparationSeparationCORECLAD% CORE% CLADEfficiencyEfficiency86.813.283.916.1103.582.0

[0036] Lab-scale tests recovered about 86.4% of the metal load in the core “bin”, with a range between about 84.7 and 88.8%, indicating that clad separation was about 103% efficient when compared to the actual value. (Some of the core alloy dissolved into the clad upon melting). The amount of clad segregated was about 82% (100−(16.1−13.2) / 16.1×100). There are some “system losses” due to a) oxidation of the melted clad and b) material hang-up.

TABLE 2EXAMPLE #1 COMPOSITION AN...

example # 2

Example #2

[0037] Hot mill trim scrap was preheated, using the method of the present invention, to 1000° F. and agitation started. When the scrap achieved the target set point of 1150° F. a five-minute countdown was started. An analysis of the weight distribution and composition of separated core and clad materials is shown in Tables 3 and 4.

TABLE 3EXAMPLE #2 WEIGHT SEPARATIONCORECLADPercentPercentActualActualSeparationSeparationCORECLAD% CORE% CLADEfficiencyEfficiency77.222.879.620.497.0111.8

[0038] Lab-scale tests recovered about 77.2% of the metal load in the core “bin”, with a range between about 76.9 and 77.4%, indicating that clad separation was about 97% efficient when compared to the actual value. (Some of the clad alloy remained adhered to the clad upon melting). The amount of clad segregated was about 111% indicating that clad material hung-up in the system from previous trials was released into this sample.

TABLE 4EXAMPLE #2 COMPOSITION ANALYSISComposition of hotmill edg...

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Abstract

The present invention relates to a method of recycling aluminum clad materials. In particular, the method relates to recycling clad materials such as brazing sheet comprised of two or more aluminum alloys, by selective melting of one of the alloys. The feedstock is agitated during heating to allow separation of the molten alloy from the unmelted core, and the molten alloy is removed, such as by draining off during the process.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method of separating and recycling metallic clad materials. In particular, the method relates to recycling clad materials such as brazing sheet comprised of two or more aluminum alloys, by selective melting of one of the alloys. BACKGROUND INFORMATION [0002] Aluminum and aluminum alloys can be joined by a wide variety of brazing and soldering processes. Brazing, by definition, employs a filler material having a liquidus above 840° F. and below the solidus of the base metal. Brazing is distinguished from soldering by the melting point of the filler metal: solders melt below 840° F. [0003] Brazing differs from welding in that no substantial amount of the base metal is melted during brazing. Thus, the temperatures for brazing aluminum are intermediate between those for welding and soldering. [0004] Brazing sheet typically consists of a low melting brazable aluminum alloy roll bonded or clad with one or more aluminum brazi...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22B7/00C22B9/16C22B21/00
CPCC22B21/0069C22B7/004Y02P10/20
Inventor LEON, DAVID D.
Owner ARCONIC INC