Method for recycling aluminum alloys and method for purifying the same

Abstract

The present disclosure relates to a method of producing a purified aluminum alloy from aluminum alloy scrap by producing a melt of aluminum alloy scrap, adding one or more intermetallic compound forming agent materials, producing iron-containing intermetallic compound particles, removing the iron-containing intermetallic compound particles, and solidifying the low-iron melt.

Description

[0001] Case information

[0002] This application is a divisional application of the invention patent application filed on August 16, 2018, with application number 201880052664.9 and invention title "Method for Recycling Aluminum Alloy and Purification Method Thereof". Technical Field

[0003] This application relates to aluminum alloys, and more specifically to methods for recycling aluminum alloys and methods for purifying them. Background Technology

[0004] Aluminum alloys can be used in a variety of applications. Some aluminum alloys are also recyclable, and recycling those conserves energy. In the United States and Canada, more than 5 million tons of aluminum are recycled annually. Summary of the Invention

[0005] In general, this disclosure relates to a method for producing purified aluminum alloys from aluminum alloy scrap. In one embodiment, the produced aluminum alloy is a 3xx aluminum casting alloy. In another embodiment, the produced aluminum alloy is one of a 3xxx or 4xxx wrought aluminum alloy. Generally, the method described herein for producing purified aluminum alloys includes melting the aluminum alloy scrap, adding one or more intermetallic former materials to the melt, and reacting the intermetallic former material (such as Si and / or Mn) with elemental iron in the aluminum alloy scrap to produce iron-containing intermetallic compound particles. The resulting iron-containing intermetallic compound particles can then be removed (e.g., by filtration). The addition of the intermetallic former material Si and / or Mn can also result in the production of alloys with increased amounts of Si and / or Mn, resulting in a 3xx aluminum casting alloy, or resulting in one of a 3xxx or 4xxx wrought aluminum alloy. Adding intermetallic compound forming agents to the melt can increase the temperature window for removing intermetallic compound particles, which in turn can increase the volume fraction of removable iron-containing intermetallic compound particles. Therefore, adding intermetallic compound forming agents to the melt can facilitate the production of suitable end-use alloys, promote iron removal from aluminum scrap within an industrially applicable temperature window, and reduce the iron content in aluminum alloys.

[0006] In one implementation scheme and now referenced Figure 1aAluminum scrap is melted using conventional methods (120), and an intermetallic compound forming agent material (130) can be added to the melt. The addition of the intermetallic compound forming agent material can result in the formation of iron-containing intermetallic compound particles (140), for example, by reacting the intermetallic compound forming agent material with iron in the melt (141). After or during their formation, the iron-containing intermetallic compound particles can be removed by any suitable method (e.g., but not limited to filtration or sedimentation) (150). Finally, the melt is solidified (160), resulting in a purified aluminum alloy (161).

[0007] More specifically and now for reference Figure 1b The system can accept aluminum alloy scrap with an initial iron (Fe) content (111) for recycling (110). For example, the initial iron content may be at least 0.2 wt.% iron (Fe) (112). In one embodiment, the initial iron content is at least 0.3 wt.% iron (Fe). In another embodiment, the initial iron content is at least 0.4 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 0.5 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 0.6 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 0.7 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 0.8 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 0.9 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 1.0 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 1.5 wt.% iron (Fe). In another embodiment, the initial iron content is at least 2.0 wt.% iron (Fe). In another embodiment, the initial iron content is at least 2.5 wt.% iron (Fe). In yet another embodiment, the initial iron content is at least 3.0 wt.% iron (Fe).

[0008] Aluminum alloy scrap is melted using conventional methods (120), and intermetallic compound forming agents such as silicon (Si) and / or manganese (Mn) can be added to the melt (131). The addition of the intermetallic compound forming agent is sufficient to generate iron-containing intermetallic compound particles in the melt (140), for example, through the reaction between Si and / or Mn and iron in the melt (141). Production can occur by cooling the melt from a first temperature to a second temperature. In some embodiments, the first temperature is the liquidus temperature of the melt. In other embodiments, the first temperature is greater than the liquidus temperature of the melt. In some embodiments, the second temperature is greater than the solidification temperature of fcc aluminum. In some embodiments, the second temperature is lower than the solidification temperature of fcc aluminum and higher than the solidus temperature of the melt. The addition of the intermetallic compound forming agent (130) can be sufficient to increase the difference between the liquidus temperature of the melt and the solidification temperature of fcc aluminum (e.g., the purification temperature window ΔT) (132). In this respect, iron-containing intermetallic compound particles can be formed within the temperature window. Typically, due to the addition of intermetallic compound forming agent material (130), the temperature window between the first and second temperatures is at least 10ºC (133). Within this temperature window (and sometimes at or below the second temperature), intermetallic compound particles can be removed by methods including, but not limited to, filtration and sedimentation of the melt (150). After removal (150), the present low-iron melt is then solidified (160) (e.g., cooled below the solidus temperature of the low-iron melt). Due to the addition of intermetallic compound forming agent material (130), the generation of iron-containing intermetallic compound particles (140), and the removal of at least some of the iron-containing intermetallic compound particles (150), the low-iron melt solidifies (160) to produce a purified aluminum alloy (161). In one embodiment, one of 3xxx or 4xxx malleable aluminum alloys can be produced (162). In another embodiment, a 3xx cast aluminum alloy can be produced (163). Due to the removal of iron-containing particles (150), the iron content of the purified aluminum alloy can be less than the initial iron content (164). For example, the iron content of purified aluminum alloys can be no more than 0.5 wt.% iron (Fe) (165).

[0009] As described above, an intermetallic compound forming agent material (131) is added to the melt, and iron-containing intermetallic compound particles (140) are generated in the melt. In one embodiment, Al-containing intermetallic compound particles (140) can be formed in the melt. 15 The intermetallic compound particles are composed of (Fe:Mn)3Si2, and the temperature window can lie between the liquidus line of the melt and the solidification temperature of fcc aluminum. In this respect, Al 15 (Fe:Mn)3Si2 particles can solidify below the liquidus line (i.e., Al...). 15(Fe:Mn)3Si2 is the first solid to form below the liquidus line. In one embodiment, due to the addition of intermetallic compound forming agent materials Si and / or Mn, the iron-containing intermetallic compound particles Al... 15 (Fe:Mn)3Si2 is removed (150), and the temperature window between the liquidus line of the melt and the solidification temperature of fcc aluminum is at least 10ºC (133).

[0010] Aluminum alloy scrap can be received in various forms (110). For example, aluminum alloy scrap can be received in the form of automotive scrap, aerospace scrap, beverage can scrap, electronic scrap, municipal scrap, etc., wherein the aluminum alloy may have industrial applicability. In this respect, the aluminum alloy scrap can be aggregated from any type of scrap (e.g., mixed stream scrap). In one embodiment, the aluminum alloy scrap is mixed stream aluminum alloy scrap. Similarly, scrap aluminum alloy can be generated as part of the conventional production of ingots, billets, or forming castings of components. In this respect, the aluminum alloy scrap can consist of at least a first scrap and a second scrap, wherein the first scrap and the second scrap are heterogeneous (e.g., have relatively different compositions). In some embodiments, the aluminum alloy scrap at least comprises a first scrap and a second scrap having relatively different compositions.

[0011] Melting (120) can be accomplished by any suitable method (such as conventional methods known in the art). After melting (120), the addition of the intermetallic compound forming agent material can be carried out at any suitable time. For example, the addition can be carried out (a) before melting, (b) during scrap melting, or (c) after the scrap has risen above its liquidus temperature (e.g., after melting). Furthermore, the intermetallic compound forming agent material can be added in any suitable form. For example, one or more intermetallic compound forming agent materials can be added in relatively pure form. For example, silicon can be added in relatively pure form, and manganese can be added in relatively pure form. Additionally, alloys containing intermetallic compound forming agent materials can be used as a source of the intermetallic compound forming agent material. For example, silicon-containing aluminum alloys or manganese-containing aluminum alloys can be added to increase the silicon and / or manganese content of the melt. In one embodiment, the intermetallic compound forming agent material manganese can be added in the form of a manganese master alloy (e.g., Mn > 10 wt.%, the remainder being substantially aluminum).

[0012] In addition to intermetallic compound forming agent materials in their relatively pure form, intermetallic compound forming agent materials can also be added in the form of the waste itself. For example, aluminum alloy waste can include at least a first waste and a second waste. In this regard, the first waste can be aluminum alloy waste having an intermetallic compound forming agent material that is insufficient to achieve the removal of iron-containing intermetallic compound particles. The second waste can be aluminum alloy waste having an intermetallic compound forming agent material (when combined with at least the first waste) sufficient to achieve the removal of iron-containing intermetallic compound particles. Furthermore, the methods described herein are not limited to adding at least a first waste and a second waste. For example, the first waste and the second waste can include aluminum alloy waste, and additional intermetallic compound forming agent materials can be added in other forms to achieve the removal and / or increased removal of iron-containing intermetallic compound particles relative to at least the first waste and the second waste.

[0013] As noted above, the addition of an intermetallic compound forming agent (e.g., silicon (Si) and / or manganese (Mn) (131)) can be sufficient to increase the difference between the liquidus temperature of the melt and the solidification temperature of fcc aluminum (sometimes referred to herein as the “purification temperature window”) (132). Iron-containing intermetallic compound particles can be removed within a purification temperature window of at least 10ºC (133). In one embodiment, the purification temperature window is at least 15ºC. In another embodiment, the purification temperature window is at least 20ºC. In yet another embodiment, the purification temperature window is at least 30ºC. In another embodiment, the purification temperature window is at least 40ºC. In yet another embodiment, the purification temperature window is at least 50ºC. In yet another embodiment, the purification temperature window is at least 60ºC. In yet another embodiment, the purification temperature window is at least 70ºC. In yet another embodiment, the purification temperature window is at least 80ºC. In yet another embodiment, the purification temperature window is at least 100ºC.

[0014] After or during its formation, ferrous intermetallic compound particles (150) can be removed by suitable methods (e.g., but not limited to filtration or sedimentation and combinations thereof). For example, various filters (e.g., filters made of refractory filter materials) can be used to filter ferrous intermetallic compound particles. Suitable refractory filter materials may include, but are not limited to, alumina, silica, silicon carbide, silicon nitride, calcium oxide, graphite, carbon, etc. In some embodiments, ferrous intermetallic compound particles are removed by filtration, wherein the filtration includes at least one refractory filter material. In this regard, multiple refractory filter materials can be used in a single filter to facilitate the removal of ferrous intermetallic compound particles from the melt. Some suitable refractory filters are disclosed in U.S. Patent No. 5,126,047.

[0015] The methods described herein can generally result in a solidified (160) purified aluminum alloy (161) with a purified iron content less than the initial iron content of the aluminum alloy scrap (164). In one method, the method can result in a purified aluminum alloy with at least 10% less iron than the aluminum alloy scrap. By a non-limiting example, aluminum alloy scrap with an initial iron content of 0.8 wt.% can be purified to have less than 10% iron. Thus, in this non-limiting example, the purified iron content would be 0.8 wt.% * (100% - 10%) = 0.72 wt.% iron (Fe). In one embodiment, the purified iron content is 15% less than the initial iron content. In another embodiment, the purified iron content is 20% less than the initial iron content. In yet another embodiment, the purified iron content is 25% less than the initial iron content. In yet another embodiment, the purified iron content is 35% less than the initial iron content. In yet another embodiment, the purified iron content is 45% less than the initial iron content. In another embodiment, the purified iron content is 60% less than the initial iron content. In yet another embodiment, the purified iron content is 75% less than the initial iron content. In yet another embodiment, the purified iron content is 85% less than the initial iron content.

[0016] In another method, the purified aluminum alloy may contain no more than 1.80 wt.% iron (Fe) (165). In one embodiment, the purified aluminum alloy contains no more than 1.5 wt.% iron (Fe). In another embodiment, the purified aluminum alloy contains no more than 1.2 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 1.0 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.8 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.5 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.40 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.35 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.30 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.25 wt.% iron (Fe). In another embodiment, the purified aluminum alloy contains no more than 0.20 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.15 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.12 wt.% iron (Fe). In yet another embodiment, the purified aluminum alloy contains no more than 0.10 wt.% iron (Fe).

[0017] Regarding solidification (160), purified aluminum alloys (161) can be cast from a low-iron melt into shaped casting parts, or can be cast into ingots / bills. The cast ingots or billets can also be remelted at a later time for shaped casting. Alternatively, the cast ingots or billets can be remelted and combined with other materials to produce a target aluminum alloy composition. For example, relatively pure aluminum can be added, and / or other alloying additives can be added to produce the desired aluminum alloy. The cast ingots or billets can be processed, for example, by hot working and / or cold working via any of rolling, forging, extrusion, and stress relief via compression and / or stretching. Shape casting of purified aluminum alloys can include any suitable shaped casting method, including permanent mold casting, high-pressure die casting, sand casting, investment casting, squeeze casting, and semi-solid casting, etc.

[0018] The purified aluminum alloy can be a Si-based aluminum alloy. For example, Si-based aluminum alloys can include 3xx cast aluminum alloys or 4xxx malleable aluminum alloys. As part of the purification method described herein, silicon (Si) can be added to the melt, and subsequently, at least some of the silicon (Si) can be retained in the purified aluminum alloy. The purified aluminum alloy can contain at least 3.0 wt.% silicon (Si) in total. In one embodiment, the purified aluminum alloy contains at least 4.0 wt.% silicon (Si). In another embodiment, the purified aluminum alloy contains at least 5.0 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains at least 6.0 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains at least 6.5 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains at least 7.0 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains at least 7.5 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains at least 8.5 wt.% silicon (Si). In another embodiment, the purified aluminum alloy contains at least 9.0 wt.% silicon (Si). In one embodiment, the purified aluminum alloy contains no more than 23.0 wt.% silicon (Si). In another embodiment, the purified aluminum alloy contains no more than 20.0 wt.% silicon (Si). In yet another embodiment, the purified aluminum alloy contains no more than 15.0 wt.% silicon (Si).

[0019] As used in this article, “3xx aluminum alloy” refers to aluminum casting alloys that contain silicon (Si) as the main alloying component, as defined in the Aluminum Association document “Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot” (2009) (also known as “Pink Sheets”).

[0020] As used in this article, “4xxx aluminum alloy” refers to a malleable aluminum alloy containing silicon (Si) as the main alloying component, as defined in the Aluminum Institute document “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” (2015) (also known as “Teal Sheets”).

[0021] In one embodiment, the method described herein for producing purified aluminum alloys is used to produce aluminum alloys consistent with those disclosed in commonly owned U.S. Patent Publication No. 2013 / 0105045. In another embodiment, the method described herein for producing purified aluminum alloys is used to produce aluminum alloys consistent with those disclosed in commonly owned U.S. Patent Publication No. 2017 / 0016092. In yet another embodiment, the method described herein for producing purified aluminum alloys is used to produce aluminum alloys consistent with those disclosed in commonly owned WIPO International Publication No. 2017 / 027734.

[0022] The purified aluminum alloy can be a Mn-based aluminum alloy. For example, Mn-based aluminum alloys can include 3xxx wrought aluminum alloys. As part of the purification method described herein, manganese (Mn) can be added to the melt, and subsequently, at least some of the manganese (Mn) can be retained in the purified aluminum alloy. The purified aluminum alloy can contain at least 0.05 wt.% manganese (Mn) in total. In one embodiment, the purified aluminum alloy contains at least 0.10 wt.% manganese (Mn). In another embodiment, the purified aluminum alloy contains at least 0.20 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains at least 0.30 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains at least 0.40 wt.% manganese (Mn). In one embodiment, the purified aluminum alloy contains no more than 1.8 wt.% manganese (Mn). In another embodiment, the purified aluminum alloy contains no more than 1.5 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains no more than 1.2 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains no more than 0.9 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains no more than 0.8 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains no more than 0.7 wt.% manganese (Mn). In yet another embodiment, the purified aluminum alloy contains no more than 0.4 wt.% manganese (Mn).

[0023] As used in this article, “3xxx aluminum alloy” refers to a malleable aluminum alloy containing manganese (Mn) as the main alloying component, as defined in the Aluminum Institute document “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” (2015) (also known as “Blue Single”).

[0024] Additionally, as used herein, the terms “3xxx aluminum alloy” or “4xxx aluminum alloy” refer only to composition and not to any associated processing; that is, as used herein, 3xxx aluminum alloy or 4xxx aluminum alloy does not need to be a forgeable product considered to be composed of 3xxx or 4xxx aluminum alloy.

[0025] To facilitate the production of suitable aluminum alloy products, additional alloying additives can be added to the melt, such as (a) before the removal of ferrous intermetallic compound particles and / or (b) after the removal of ferrous intermetallic compound particles. Alternatively, additional alloying additives can be added during (c) or after (d) the remelting and purification of the aluminum alloy (e.g., before forming casting or casting into ingots / bills). Alloying additives can be added to tailor the physical properties of the purified aluminum alloy (e.g., tensile properties; toughness; corrosion resistance; others).

[0026] As used herein, "other alloying additives" or "alloying additives" means elements other than aluminum, silicon, iron, and manganese that can be intentionally added to a melt (e.g., to produce a pre-selected target composition and ultimately a pre-selected solidified alloy product). Other alloying additives can be added to promote the achievement of desired physical properties of the pre-selected target composition. Other alloying additive elements include chromium (Cr), nickel (Ni), zinc (Zn), titanium (Ti), tin (Sn), and strontium (Sr), etc. In one embodiment, the alloying additive comprises at least one of copper (Cu) or magnesium (Mg).

[0027] Components can be produced from purified aluminum alloys. For example, purified aluminum alloys can be used to form cast components. Components made from purified aluminum alloys can be used in any suitable application, such as automotive, aerospace, industrial, or commercial transportation applications. In one embodiment, the purified aluminum alloy component is an automotive part (e.g., body-in-white (BIW) part; suspension part). In one embodiment, the purified aluminum alloy component is included in an automobile. In one embodiment, the purified aluminum alloy component is an aerospace component. In one embodiment, the purified aluminum alloy component is included in an aerospace vehicle. In one embodiment, the purified aluminum alloy component is an industrial component. In one embodiment, the purified aluminum alloy component is a commercial transportation component. In one embodiment, the purified aluminum alloy component is included in a commercial transportation vehicle.

[0028] The custom addition of intermetallic compound forming agent materials (optionally together with other alloying additives) facilitates the production of predetermined low-iron aluminum alloys from aluminum alloy scrap. In one embodiment and now referenced... Figure 1cThe method described herein is used to preselect a target purified aluminum alloy composition (210) for production. In this regard, the preselected target composition may be one of 3xx cast aluminum alloys, or 3xxx or 4xxx malleable aluminum alloys. Based on the preselection step and the composition of the aluminum alloy scrap, a specific amount of intermetallic compound forming agent material may be added to the aluminum alloy scrap (220). The composition of the aluminum alloy scrap may be determined before adding the specific amount of intermetallic compound forming agent material and / or other alloying additives (221). In this way, the specific amount of intermetallic compound forming agent material may be sufficient to achieve the removal of iron-containing intermetallic compound particles (225). The specific amount of intermetallic compound forming agent material that can be added may be selected using any suitable method. In this regard, the addition of intermetallic compound forming agent material may be selected based on experimental results or based on recycling simulations (e.g., modeling). For example, a simulation database may be used to calculate an appropriate amount of intermetallic compound forming agent material sufficient to achieve the removal of iron-containing intermetallic compound particles. After removing iron-containing intermetallic compound particles (225) using the methods described herein and / or using any other alloying additives (222), a purified aluminum alloy with a preselected target composition can be produced. As will be understood, the target composition can be considered as a compositional range. Attached Figure Description

[0029] Figure 1a This is an implementation plan for producing purified aluminum alloy.

[0030] Figure 1b An implementation scheme for producing purified aluminum alloys using intermetallic compound forming agent materials silicon (Si) and / or manganese (Mn).

[0031] Figure 1c This is an implementation scheme for producing purified aluminum alloys with pre-selected target compositions.

[0032] Figure 2a The image is a MIC6 in as-cast state, taken at 300x magnification. ® Micrographs of the alloy.

[0033] Figure 2b The as-cast MIC6 was photographed at 3000x magnification. ® Micrographs of the alloy.

[0034] Figure 3a It is made by Pandat ® MIC6 generated in Example 1 ® Solidification path diagram of the alloy, where the solids fraction ranges from 0 to 1.

[0035] Figure 3b It is made by Pandat ®MIC6 generated in Example 1 ® Solidification path diagram of the alloy, where the solids fraction ranges from 0 to 0.2.

[0036] Figure 4a It is made by Pandat ® MIC6 generated in Example 1 ® Solidification path diagrams for Alloy 1 and Alloy 2, where the solid fraction ranges from 0 to 1.

[0037] Figure 4b It is made by Pandat ® MIC6 generated in Example 1 ® Solidification path diagrams for Alloy 1 and Alloy 2, where the solid fraction ranges from 0 to 0.2.

[0038] Figure 5 It is made by Pandat ® The generated solidification path diagram and the curve of liquid aluminum Mn and Fe composition in liquid aluminum, where the solid fraction ranges from 0 to 1.

[0039] Figure 6a It is a contour plot that shows the effect of adding intermetallic compound forming agents Si and Mn on the minimum possible iron content in the recycling simulation.

[0040] Figure 6b The plot shows the effect of adding intermetallic compound forming agents Si and Mn on the purification temperature window in the recycling simulation.

[0041] Figure 6c It is a contour plot that shows the effect of adding alloying additives Cu and Mg on the minimum possible iron content in the recycling simulation.

[0042] Figure 6d It is a contour plot that shows the effect of adding alloying additives Cu and Mg on the purification temperature window in the recycling simulation.

[0043] Figure 7 This is a data table of the recycling simulation of Example 3, which shows the solid fraction, liquid aluminum composition and precipitated phase.

[0044] Figure 8 This is a data table of the recycling simulation of Example 4, which shows the solid fraction, liquid aluminum composition and precipitated phase.

[0045] Figure 9 This is a data table of the recycling simulation of Example 5, which shows the solid fraction, liquid aluminum composition and precipitated phase.

[0046] Figure 10 This is a data table of the recycling simulation of Example 6, which shows the solid fraction, liquid aluminum composition and precipitated phase.

[0047] Figure 11 This is a data table of the recycling simulation of Example 7, which shows the solid fraction, liquid aluminum composition and precipitated phase. Detailed Implementation

[0048] Example 1

[0049] Recyclable MIC6 ® Aluminum alloys are cast into ingots. Table 1a lists the aluminum alloy MIC6. ® Typical components.

[0050] Table 1a: Aluminum Alloy MIC6 ® Composition

[0051]

[0052] Take microscopic photographs of cast aluminum alloys. Figure 2a and Figure 2b The images shown are micrographs taken at 300x and 3000x magnification. As shown, the as-cast microstructure of the aluminum alloy contains intermetallic compound phases. These intermetallic compound phases exhibit a Chinese script-like structure and were identified as Al using SEM-EDX analysis. 15 (Fe:Mn)3Si2. The composition of the intermetallic compound phase was further confirmed by constructing Pandat using the compositions given in Table 1. ® Phase diagrams and solidification pathway analysis. For example... Figures 3a to 3b The image shown is made by Pandat ® The constructed phase diagram illustrates the solidification path. For example... Figure 3b As shown, a small purification temperature window of 2.5ºC exists, in which solid intermetallic compounds Al, which do not contain solid aluminum, are formed. 15 (Fe:Mn)3Si2. In principle, the intermetallic compound Al can be separated from the liquid phase (e.g., by filtration) within a 2.5ºC temperature window. 15 (Fe:Mn)3Si2 particles. However, in practice, the temperature window (2.5ºC) is too small to achieve significant separation.

[0053] To MIC6 ® The addition of intermetallic compound forming agents silicon and manganese to alloys alters the solidification pathway. See Table 1b and... Figures 4a-4b As shown, the addition of manganese (“Alloy 1”) and the combination of silicon and manganese (“Alloy 2”) increased the purification temperature window (ΔT) and the intermetallic compound Al. 15 The solid fraction of (Fe:Mn)3Si2.

[0054] Table 1b: Intermetallic compound forming agents for alloy MIC6 ® Impact

[0055]

[0056] Figure 5 The solids fraction, iron and manganese composition in bulk aluminum, and phase transformation temperature of Alloy 2 are shown. As illustrated, the intermetallic compound Al... 15 (Fe:Mn)3Si2 begins to form at approximately 690ºC. At 592ºC, solid aluminum (fcc) reaches equilibrium with the intermetallic compound phase and the liquid phase. Therefore, there exists a temperature window of approximately 97ºC from 592ºC to 690ºC, during which the intermetallic compound Al... 15 (Fe:Mn)3Si2 particles can be separated from the liquid aluminum phase where solid aluminum is absent. This purification temperature window of approximately 97ºC is sufficient to separate intermetallic compound particles from bulk liquid aluminum. In one method, the purification temperature window is at least 10ºC to separate intermetallic compound particles from bulk liquid aluminum.

[0057] like Figure 5 As shown, this can be achieved by adding an intermetallic compound forming agent and removing the intermetallic compound Al. 15 (Fe:Mn)3Si2 particles are used to reduce iron in bulk aluminum. As shown, at the freezing point of fcc aluminum (592ºC), the iron concentration in aluminum decreases from 0.53 wt.% to approximately 0.05 wt.%. However, achieving the separation of 0.05 wt.% iron in bulk aluminum without removing solid aluminum is highly impractical. Therefore, in one method, intermetallic compound particles are removed at a temperature above the aluminum freezing temperature (e.g., 10ºC–20ºC higher) (e.g., by filtration), thereby avoiding the removal of solid aluminum.

[0058] Example 2

[0059] Aluminum alloy purification, which involves adding intermetallic compound forming agents and removing iron-containing intermetallic compound particles, can be performed on various aluminum alloys. In this regard, recyclability process models were constructed for other common aluminum alloy compositions. Thermodynamic simulation software Pandat was used. ® and the accompanying aluminum thermodynamics database PanAluminum ® To construct the process model. As described in more detail below, intermetallic compound forming agents are selected for each aluminum alloy composition. The mixture of intermetallic compound forming agents and aluminum alloys provides a process model with overall composition. Pandat ® The minimum iron concentration of the mixture and the corresponding purification temperature window (ΔT) are determined using the overall composition.

[0060] Intermetallic compound forming agents were selected for each recycling process. The mass of the intermetallic compound forming agent was selected using a Java script that matched the amount of the intermetallic compound forming agent with the composition in a simulation database that achieved good separation results. In this method, the mass of the intermetallic compound forming agent was selected based on maximizing ΔT and minimizing the iron concentration. The simulation database contained 11,520 simulations using each combination of elements and compositions provided in Table 2 below.

[0061] Table 2: Elements and Composition of the Simulation Database

[0062]

[0063] The 11,520 simulations were then used to construct contour maps. Figures 6a-6b A contour plot is shown for an aluminum alloy having 2.25 wt.% Cu, 0.7 wt.% Mg, and 0.5 wt.% Zn. The plot illustrates the effects of Mn and Si, as intermetallic compound forming agents, on iron concentration and purification temperature window. As shown, increasing Si and Mn content decreases iron concentration and increases the purification temperature window. For the shown range of Si and Mn content and given composition, the iron concentration varies from 0.10 wt.% to approximately 0.70 wt.%, and the purification temperature window varies from 20ºC to approximately 100ºC. Figures 6c-6d A contour plot is shown for an aluminum alloy having 2.0 wt.% Mn, 10.0 wt.% Si, and 0.5 wt.% Zn, illustrating the effects of Cu and Mg on the minimum possible iron concentration and the purification temperature window. As shown, increasing the Cu and Mg content decreases the iron concentration and increases the purification temperature window. For the indicated Cu and Mg content range and given composition, the iron concentration varies from 0.11 wt.% to approximately 0.14 wt.%, and the purification temperature window varies from 94ºC to approximately 104ºC.

[0064] Example 3

[0065] Using the simulation methodology of Example 2, an alloy (“Alloy 3”) having the composition shown in Table 3b below was simulated. (1) In the form of a manganese master alloy (85 wt.% Al and 15 wt.% Mn) and (2) in the form of pure silicon, an intermetallic compound forming agent with added manganese and silicon was simulated. The simulation yielded the lowest possible iron composition of about 0.10 wt.% at a temperature of 600.2ºC, providing a purification temperature window of about 77ºC. The simulation showed that when filtered at a temperature of about 10ºC-20ºC above the solidification temperature of aluminum, a final alloy composition of 0.13-0.17 wt.% iron was achieved by removing the intermetallic compound phase. The masses of Alloy 3 and the intermetallic compound forming agent are provided in Table 3a below. The composition of Alloy 3, the melt composition (overall composition of Alloy 3 and the intermetallic compound forming agent), and the final melt composition after purification are given in Table 3b. Figure 7 The complete dataset for the recirculation simulation is shown in the figure.

[0066] Table 3a: Mass of materials in Example 3

[0067]

[0068] Table 3b: Process Components of Example 3

[0069]

[0070] Example 4

[0071] Using the methodology of Example 2, a mixture of two alloys (“Alloy 4a” and “Alloy 4b”) having the compositions shown in Table 4b below was simulated. Alloy 4a is a typical 6061 aluminum alloy. (1) Manganese and silicon, intermetallic compound forming agents, were added in the form of a manganese master alloy (85 wt.% Al and 15 wt.% Mn) and (2) pure silicon. Pure copper was also added to increase the copper level in the alloy to about 1.0 wt.%. The simulation yielded the lowest possible iron composition of about 0.08 wt.% at a temperature of about 594.9ºC, providing a purification temperature window of about 105ºC. The simulation showed that a final alloy composition of 0.11–0.14 wt.% iron was achieved by removing the intermetallic compound phase when filtration was performed at a temperature of about 10ºC–20ºC above the solidification temperature of aluminum. The masses of Alloy 4a, Alloy 4b, Mn master alloy, pure Si, and pure copper are provided in Table 4a below. Table 4b shows the composition of alloys 4a and 4b, the melt composition (overall composition of alloys 4a, 4b, Mn master alloy, pure Si and pure copper), and the final melt composition after purification. Figure 8 A more complete dataset for the recirculation simulation is provided in the paper.

[0072] Table 4a: Mass of materials in Example 4

[0073]

[0074] Table 4b: Process Components of Example 4

[0075]

[0076] Example 5

[0077] Using the methodology of Example 2, a mixture of two alloys (“Alloy 5a” and “Alloy 5b”) having the compositions shown in Table 5b below was simulated. (1) In the form of a manganese master alloy (85 wt.% Al and 15 wt.% Mn) and (2) in the form of pure silicon, intermetallic compound forming agents manganese and silicon were added. The simulation produced the lowest possible iron composition of about 0.08 wt.% at a temperature of about 592.7ºC, providing a purification temperature window of about 84ºC. The simulation showed that when filtered at a temperature of about 10ºC-20ºC above the solidification temperature of aluminum, a final alloy composition of 0.10-0.13 wt.% iron was achieved by removing the intermetallic compound phase. The masses of Alloy 5a, Alloy 5b, Mn master alloy and pure Si are provided in Table 5a below. The compositions of Alloy 5a and Alloy 5b, the melt composition (overall composition of Alloy 5a, Alloy 5b, Mn master alloy and pure Si) and the final melt composition after purification are given in Table 5b. Figure 9 A more complete dataset for the recirculation simulation is provided in the paper.

[0078] Table 5a: Mass of materials in Example 5

[0079]

[0080] Table 5b: Process Composition of Example 5

[0081]

[0082] Example 6

[0083] Using the methodology of Example 2, a mixture of two alloys (“Alloy 6a” and “Alloy 6b”) having the compositions shown in Table 6b below was simulated. Silicon, an intermetallic compound forming agent, was added in the form of pure silicon. The simulation yielded a minimum possible iron composition of approximately 0.10 wt.% at a temperature of approximately 597.9ºC, providing a purification temperature window of approximately 67ºC. The simulation showed that when filtered at approximately 10ºC–20ºC above the solidification temperature of aluminum, a final alloy composition of 0.12–0.16 wt.% iron was achieved by removing the intermetallic compound phase. The masses of Alloy 6a, Alloy 6b, and pure Si are provided in Table 6a below. Table 6b shows the compositions of Alloy 6a and Alloy 6b, the melt composition (overall composition of Alloy 6a, Alloy 6b, and pure Si), and the final melt composition after purification. Figure 10 A more complete dataset for the recirculation simulation is provided in the paper.

[0084] Table 6a: Mass of materials in Example 6

[0085]

[0086] Table 6b: Process Components of Example 6

[0087]

[0088] Example 7

[0089] Using the methodology of Example 2, simulations were performed on an alloy (“Alloy 7”) having the composition shown in Table 7b below. Silicon, an intermetallic compound forming agent, was added in the form of pure silicon. Pure copper was also added to increase the copper level in the alloy to approximately 1.9 wt.%. The simulations yielded the lowest possible iron composition of approximately 0.09 wt.% at a temperature of approximately 595.1ºC, providing a purification temperature window of approximately 100ºC. The simulations showed that a final alloy composition of 0.12–0.15 wt.% iron was achieved by removing the intermetallic compound phase when filtration was performed at approximately 10–20ºC above the aluminum solidification temperature. The masses of Alloy 7, the Mn master alloy, and pure Si are provided in Table 7a below. The composition of Alloy 7, the melt composition (overall composition of Alloy 7, pure silicon, and pure copper), and the final melt composition after purification are given in Table 7b. Figure 11 A more complete dataset for the recirculation simulation is provided in the paper.

[0090] Table 7a: Mass of materials in Example 7

[0091]

[0092] Table 7b: Process Components of Example 7

[0093]

Claims

1. A method for producing an alloy from scrap, comprising: (a) Melting aluminum alloy scrap to produce a melt, wherein the aluminum alloy scrap contains an initial iron content, wherein the initial iron content is at least 0.20 wt.% iron; (b) Adding excess manganese to the melt, wherein the excess manganese is sufficient to produce (i) iron-containing intermetallic compound particles in the melt and (ii) manganese-based aluminum alloys from the melt; (c) Forming the iron-containing intermetallic compound particles in the melt, wherein a first amount of manganese reacts with the iron in the melt to form the iron-containing intermetallic compound particles, and wherein a second amount of manganese remains in the melt in an unreacted form, the second amount of manganese corresponding to the amount of excess manganese required to produce the manganese-based aluminum alloy from the melt in the addition step (b); (d) Remove at least some of the iron-containing intermetallic compound particles from the melt to produce a low-iron melt having the second amount of manganese therein; (e) Solidify the low-iron melt to produce the manganese-based aluminum alloy having the second amount of manganese, wherein the manganese-based aluminum alloy contains purified iron content, wherein the purified iron content is less than the initial iron content and not more than 0.5 wt.% of iron, and wherein the manganese-based aluminum alloy contains manganese as the main alloying component other than aluminum.

2. The method according to claim 1, wherein the manganese-based aluminum alloy is an Al-Si alloy containing at least 4.0 wt.% Si.

3. The method according to claim 1, wherein the manganese-based aluminum alloy is one of 3xx aluminum casting alloy or 4xxx malleable aluminum alloy.

4. The method according to claim 1, wherein the manganese-based aluminum alloy contains no more than 0.35 wt.% iron.

5. The method of claim 1, wherein the manganese-based aluminum alloy contains no more than 0.20 wt.% iron.

6. The method of claim 1, wherein the manganese-based aluminum alloy contains no more than 0.15 wt.% iron.

7. The method of claim 1, wherein the addition step (b) comprises adding sufficient amounts of silicon and manganese to produce the low-iron melt, wherein the low-iron melt contains no more than 1.8 wt.% manganese.

8. The method according to claim 1, wherein the purified aluminum alloy is a 3xxx malleable aluminum alloy.

9. The method according to claim 1, wherein the forming step comprises: (i) Cooling the melt from a first temperature to a second temperature to produce the iron-containing intermetallic compound particles.

10. The method of claim 9, further comprising: The removal step is completed at a temperature equal to or lower than the second temperature.

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