Recycling of aerospace chips

Abstract

A method of recycling aerospace aluminum chips includes melting the aerospace aluminum chips to obtain an initial melt and subjecting the initial melt to a metal treatment to produce a cleaned melt. The metal treatment may include filtering the initial melt using an intermediate filter to produce an intermediate melt, cleaning the intermediate melt, and / or purifying the intermediate melt. The metal treatment may include conducting density separation of the intermediate melt, skimming the intermediate melt (by salt or gas treatment), and / or filtering the skimmed intermediate melt using a fine filter to produce a filtered melt. The metal treatment may be repeated until a chemistry or inclusion level of the filtered melt is at a desired level. After metal treatment, the method may include solidifying the cleaned melt into an intermediate sow and / or transferring the cleaned melt to a casting system.

Description

Patent Application Attorney Docket #: 108050-1483284 RECYCLING OF AEROSPACE CHIPS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 557,099, filed on February 23, 2024, and entitled RECYCLING OF AEROSPACE CHIPS, the content of which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION

[0002] This application relates to the systems and methods for cleaning and recycling metals scrap or chips (hereinafter “chips”), and more particularly to systems and methods for cleaning and recycling aerospace chips. BACKGROUND

[0003] Metal chips are generated in various industries during various manufacturing processes that produce various metal products. As an example, the aerospace industry generates a significant amount of metal chips by machining, cutting, and / or otherwise transforming an intermediate metal product of aluminum or an aluminum alloy to produce a finished metal product such as structural parts or components of an aircraft made of aluminum or an aluminum alloy. However, the chips generated by such manufacturing processes, particularly from the aerospace industry, are difficult to recycle because the chips are not adequately sorted and are commonly mixed with other material, which limits the recycling tolerance of a specific product. In addition, recycling of aerospace chips is difficult because the chips may have lubricant on their surface, and such lubricant may increase an amount of carbide when the chips are melted. Recycling of aerospace chips is additionally difficult because the chips have a high surface area and a low bulk density, which causes a high proportion of surface oxide layers and an increased amount of melting loss. Due to such difficulties, the quality of any intermediate metal product generated by the recycling of aerospace chips is below the quality required in the aerospace industry and thus are used in different industries, and no processes currently exist for recycling aerospace chips into aerospace material of the same quality. SUMMARY

[0004] Embodiments covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various embodiments and introduces some of the concepts that are further described in the Detailed Description section below. ThisPatent Application Attorney Docket #: 108050-1483284 summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings, and each claim.

[0005] According to certain embodiments, a method of recycling aerospace aluminum chips includes subjecting the aerospace aluminum chips to a pretreatment by drying the aerospace aluminum chips at a temperature at or below 400 °C for a duration of less than or equal to 60 minutes to produce pretreated chips. The method includes melting the pretreated chips to obtain an initial melt and subjecting the initial melt to a metal treatment to produce a cleaned melt. In certain embodiments, the metal treatment includes (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and (vi) filtering the skimmed intermediate melt using a fine filter. The method may include solidifying the cleaned melt into an intermediate sow.

[0006] According to various embodiments, a method of recycling aerospace aluminum chips includes melting the aerospace aluminum chips to obtain an initial melt and subjecting the initial melt to a metal treatment to produce a cleaned melt. In certain embodiments, the metal treatment includes filtering the initial melt using an intermediate filter to produce an intermediate melt, cleaning the intermediate melt, and purifying the intermediate melt. The metal treatment may further include conducting density separation of the intermediate melt, skimming the intermediate melt, and filtering the skimmed intermediate melt using a fine filter to produce a filtered melt. In some embodiments, the metal treatment includes determining an inclusion level of the filtered melt and repeating the metal treatment steps until the inclusion level is at a target level for the cleaned melt. The method may include solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

[0007] According to certain embodiments, a method of recycling aerospace aluminum chips includes subjecting the aerospace aluminum chips to a pretreatment to produced pretreated chips, melting the pretreated chips to obtain an initial melt, and subjecting the initial melt to a metal treatment to produce a clean melt. The metal treatment may include (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and (vi) filtering the skimmedPatent Application Attorney Docket #: 108050-1483284 intermediate melt using a fine filter. In some embodiments, the method includes solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

[0008] Various implementations described herein can include additional systems, methods, features, and advantages, which cannot necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The specification makes reference to the following appended figure, in which use of like reference numerals is intended to illustrate like or analogous components.

[0010] FIG. 1 illustrates a process for recycling aerospace aluminum chips according to embodiments. DETAILED DESCRIPTION

[0011] Described herein are systems and methods for the recycling of aerospace aluminum chips. In some embodiments, the systems and methods described herein may be closed-loop systems and methods. However, in other embodiments, the systems and methods described herein need not be closed-loop, and instead the systems and methods described herein may be applied for the recycling of aerospace aluminum chips from any source.

[0012] The systems and methods described herein may provide a sustainable way to recycle aerospace aluminum chips and transform them into high-quality aerospace products. In other words, unlike traditional recycling approaches in which recycled aerospace aluminum chips lack the quality to be re-used in the aerospace industry, the recycled aluminum produced by the systems and methods described herein may meet the quality requirements and therefore may be re-used within the same industry. The systems and methods described herein may require minimal prime aluminum to produce aerospace-grade aluminum products, may lower costs, and minimize waste. In some embodiments, the systems and methods described herein may produce ingots for aerospace applications with 10-100% recycled content, and in one non- limiting example, may produce an ingot with 70% recycled content. The systems and methods described herein may be useful for recycling various aluminum alloys used in the aerospacePatent Application Attorney Docket #: 108050-1483284 industry, and may be particularly useful for recycling and producing a recycled ingot of a 2xxx series aluminum alloy and / or 7xxx series aluminum alloy.

[0013] As a non-limiting example, the systems and methods described herein may produce an ingot of a 2xxx series aluminum alloy according to one of the following aluminum alloy designations: AA2001, A2002, AA2004, AA2005, AA2006, AA2007, AA2007A, AA2007B, AA2008, AA2009, AA2010, AA2011, AA2011A, AA2111, AA2111A, AA2111B, AA2012, AA2013, AA2014, AA2014A, AA2214, AA2015, AA2016, AA2017, AA2017A, AA2117, AA2018, AA2218, AA2618, AA2618A, AA2219, AA2319, AA2419, AA2519, AA2021, AA2022, AA2023, AA2024, AA2024A, AA2124, AA2224, AA2224A, AA2324, AA2424, AA2524, AA2624, AA2724, AA2824, AA2025, AA2026, AA2027, AA2028, AA2028A, AA2028B, AA2028C, AA2029, AA2030, AA2031, AA2032, AA2034, AA2036, AA2037, AA2038, AA2039, AA2139, AA2040, AA2041, AA2044, AA2045, AA2050, AA2055, AA2056, AA2060, AA2065, AA2070, AA2076, AA2090, AA2091, AA2094, AA2095, AA2195, AA2295, AA2196, AA2296, AA2097, AA2197, AA2297, AA2397, AA2098, AA2198, AA2099, or AA2199.

[0014] As another non-limiting example, the systems and methods described herein may produce an ingot of a 7xxx series aluminum alloy according to one of the following aluminum alloy designations: AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028, AA7030, AA7031, AA7033, AA7035, AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA7049, AA7049A, AA7149, AA7249, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7250, AA7055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099.

[0015] Various other benefits and advantages may be realized with the systems and methods described herein, and the aforementioned benefits and advantages should not be considered limiting.

[0016] FIG.1 illustrates a process 100 for recycling aerospace aluminum chips and to make ingots that can be used in the aerospace industry starting from such aluminum chips. In general,Patent Application Attorney Docket #: 108050-1483284 the process 100 includes the steps of: inputting or supplying the aluminum chips (step 102), optionally pretreating the aluminum chips (step 104), melting the aluminum chips into an initial melt (step 106), treating the initial melt to form a clean melt (step 108), holding and / or transferring the clean melt (step 110), and casting the clean melt into an ingot and producing a product (step 112). The various steps of the process may be implemented continuously, semi- continuously, and / or discontinuously. In certain embodiments, some steps may be performed in one manner (e.g., continuously), and other steps may be performed in another manner (e.g., semi-continuously) as desired. Each of the steps is described in greater detail below. Unless stated otherwise, the steps 102-112 illustrated in FIG.1 are implemented successively. Input Step

[0017] In the step 102, the process 100 includes supplying or collecting aerospace aluminum chips to be recycled. The aerospace aluminum chips collected in step 102 may be provided directly and / or indirectly from various sources (also referred to as machine or machining centers) and may come in various forms. As non-limiting examples, the process 100 may collect and / or supply aerospace aluminum chips directly from a manufacturer, machine, and / or machining center, and / or the process 100 may collect and / or supply aerospace aluminum chips from scrap dealers, scrap traders, and / or otherwise indirectly as desired.

[0018] In some embodiments, the aerospace aluminum chips may be collected in segregated form (e.g., based on aluminum alloys such as 7075 aluminum alloys and 7050 aluminum alloys), while in other embodiments the aerospace aluminum chips may be collected in mixed form (e.g., mixed with other alloy chips). In embodiments where the aluminum chips are mixed, step 102 may further include sorting the aluminum chips into various alloys using various techniques as desired. Sorting techniques may include, but are not limited to, optical- based sorting techniques, laser-induced breakdown spectroscopy (LIBS) techniques, x-ray fluorescence (XRF) sorting techniques, x-ray transmission (XRT) sorting techniques, combinations thereof, and / or other sorting techniques as desired.

[0019] In addition to be segregated or mixed, the aluminum chips may be wet (e.g., with moisture and / or oil on surfaces of the aluminum chips) or dry. Optionally, when the aluminum chips are wet, step 102 optionally includes drying the aluminum chips to remove water and / or oil from the surfaces of the aluminum chips. Various drying techniques may be utilized to remove water and / or oil from the surfaces of the aluminum chips, including but not limited toPatent Application Attorney Docket #: 108050-1483284 naturally drying the aluminum chips, heating the aluminum chips, centrifuging the aluminum chips, combinations thereof, and / or other techniques as desired.

[0020] In some embodiments, the collected aluminum chips may be collected in loose form or as compressed compacts. The compressed compacts may be in various shapes as desired, such as but not limited to cylindrical, rectangular, and / or square. Optionally, the compacts are high-density compacts with thickness from about 25 mm to about 70 mm, such as about 25 mm, about 30 mm, about 35 mm, about 40 mm, about 45 mm, about 50 mm, about 55 mm, about 60 mm, about 65 mm, and / or about 70 mm. In other embodiments, the thickness of the compacts may be less than 25 mm and / or may be greater than 70 mm. Optionally, the high- density compacts may have widths from about 50 mm to about 170 mm, such as about 50 mm, about 55 mm, about 60 mm, about 65 mm, about 70 mm, about 75 mm, about 80 mm, about 85 mm, about 90 mm, about 95 mm, about 100 mm, about 105 mm, about 110 mm, about 115 mm, about 120 mm, about 125 mm, about 130 mm, about 135 mm, about 140 mm, about 145 mm, about 150 mm, about 155 mm, about 160 mm, about 165 mm, and / or about 170 mm. In other embodiments, the widths of the compacts may be less than 50 mm and / or greater than 170 mm. In other embodiments, the compacts may be medium-density compacts and / or low density compacts of other dimensions as desired. As a non-limiting example, a medium density compact may have a thickness greater than 70 mm and / or a width greater than 170 mm, such as but not limited to a thickness of at least 600 mm and / or a width of at least 600 mm. In other embodiments, the dimensions of the compact may be provided and / or determined independent of the density of the compact.

[0021] In embodiments where the collected chips are in loose form, step 102 optionally includes compressing the aluminum chips into compacts of various densities and / or receiving compacts of chips having various densities. As non-limiting examples, loose aluminum chips may be compressed into medium density compacts, loose aluminum chips may be compressed into high density compacts, and / or the compacts received may be baled chips with a lower density, baled chips with a medium density, and / or baled chips with a high density as desired.

[0022] In summary, depending on the initial form and source of the aluminum chips, step 102 includes receiving the aerospace aluminum chips, optionally sorting the aluminum chips, and optionally compressing the aluminum chips into one or more compacts. The aluminum chips from step 102 generally may be considered to be wet compact chips, dry compact chips, wet loose chips, and dry loose chips.Patent Application Attorney Docket #: 108050-1483284 Pretreatment Step

[0023] In the optional step 104, the process 104 may include applying one or more pretreatments to the input aluminum chips from step 102 to form pretreated chips. In various embodiments, and as discussed in detail below, depending on the form of the input aluminum chips from step 102, various pretreatments may be applied, such as but not limited to a drying process, a breaking process, a sieving process, and / or a lubricant removal process to form the pretreated chips. In some embodiments, step 104 may be omitted from the process 100.

[0024] In embodiments where the input aluminum chips from step 102 are wet chips, step 104 may include performing a drying process to dry the chips. In some embodiments, the drying process may include naturally drying the aluminum chips. In one non-limiting example, naturally drying the aluminum chips may include storing the aluminum chips under a roof for at least seven days without cover. However, in other embodiments, other durations may be utilized as desired to naturally dry the aluminum chips. Optionally, the wet aluminum chips may be naturally dried until the chips lose 35 wt.% (e.g., due to the drying of lubrication and / or water). Additionally, or alternatively, the drying process may include artificially drying the aluminum chips using a heating or drying source. In certain embodiments, a temperature of the artificial drying process may be greater than a temperature of the natural drying process, and / or a duration of the artificial drying process may be less than a duration of the natural drying process. As one non-limiting example, artificially drying the aluminum chips may include drying the aluminum chips at a temperature at or below 400 °C for a duration of less than or equal to 60 minutes, such as a duration of 30 to 60 minutes. In such an example, the chips may be dried under a flow of hot air or gas, and the chips optionally may be moved and / or vibrated during drying to gradually heat the chips. In embodiments where the input aluminum chips from step 102 are dry, the dry aluminum chips may be subjected to one or more drying processes; however, in other embodiments, the dry aluminum chips need not be subjected to a drying process.

[0025] In some embodiments, the artificial drying process may also be considered a preheating process for preheating the chips before the melting step 106. In such an embodiment, the preheating process may include heating the chips to a preheat temperature from about 150 °C to about 400 °C, such as about 150 °C, about 155 °C, about 160 °C, about 165 °C, about 170 °C, about 175 °C, about 180 °C, about 185 °C, about 190 °C, about 195 °C,Patent Application Attorney Docket #: 108050-1483284 about 200 °C, about 205 °C, about 210 °C, about 215 °C, about 220 °C, about 225 °C, about 230 °C, about 235 °C, about 240 °C, about 245 °C, about 250 °C, about 255 °C, about 260 °C, about 265 °C, about 270 °C, about 275 °C, about 280 °C, about 285 °C, about 290 °C, about 295 °C, about 300 °C, about 305 °C, about 310 °C, about 315 °C, about 320 °C, about 325 °C, about 330 °C, about 335 °C, about 340 °C, about 345 °C, about 350 °C, about 355 °C, about 360 °C, about 365 °C, about 370 °C, about 375 °C, about 380 °C, about 385 °C, about 390 °C, about 395 °C, and / or about 400 °C. In one non-limiting example, preheating may include heating the chips to a preheat temperature of at least 150 °C.

[0026] In embodiments where the input aluminum chips from step 102 are compact chips, pretreatment in step 104 may include breaking the compact into pieces using various techniques as desired. As one non-limiting example, breaking the compact into pieces may include crushing the compact into pieces of broken compact.

[0027] In certain embodiments, the pieces of broken compact and / or the loose chips may undergo magnetic separation, shredding, and sieving as pretreatment in step 104.

[0028] In various embodiments, depending on the lubricant content, the sieved chips may be centrifuged, heat-treated, chemically washed, and / or otherwise treated to remove the lubricant. In certain embodiments, such lubricant removal processes may be performed on the input aluminum chips from step 102 that were wet, and need not be performed on the dry input aluminum chips from step 102.

[0029] Optionally, pretreatment step 104 includes extruding the pretreated chips to form a continuous extrusion as the pretreated chips. In such embodiments, forming the extrusion as the pretreatment may increase the density of the pretreated chips to improve submergence during melting in step 106. Such a pretreatment step may additionally allow for the extrusion and / or the pretreated chips to be continuously fed to a first furnace for the melting step 106.

[0030] In summary, depending on form of the input aluminum chips from step 102 (e.g., wet or dry, compact or loose, etc.), pretreatment step 104 of the input aluminum chips to form pretreated chips may include optionally drying the aluminum chips, optionally breaking compacts into pieces of broken compact, magnetic separation, shredding (e.g., magnetic shredding, mechanical shredding, etc.), sieving, and optionally lubricant removal. Melting StepPatent Application Attorney Docket #: 108050-1483284

[0031] The melting step 106 is utilized for melting the pretreated chips from step 104 and / or the input chips from step 102 (e.g., when pretreatment is omitted) to obtain an initial melt. In various embodiments, in addition to melting the chips and recovering aluminum, melting step 104 may include removing inert oxides, carbides, borides, and salt from any dross generated.

[0032] In various embodiments, melting step 106 may be implemented using various furnaces as desired, such as but not limited to a rotary furnace, a single crucible furnace, an induction furnace, and / or a sidewell furnace. Optionally, energy-efficient burners, such as but not limited to plasma, may be utilized.

[0033] In one non-limiting example, wet compact chips, wet loose chips, dry compact chips, and / or dry loose chips may be melted using a rotary furnace and / or a single crucible furnace. In such an example, lubricant and / or organic material on the surface of the chips optionally may be utilized as fuel to melt the chips, thereby reducing fuel usage by the first furnace. As a non-limiting example, off-gas may be analyzed and monitored for providing feedback to control an air-to-fuel ratio, thereby providing fuel and energy savings.

[0034] In yet another non-limiting example, dry loose chips may be melted using an induction furnace in which a vortex is generated. In a further non-limiting example, dry loose chips may be melting using a sidewell furnace in which a vortex is generated by mechanical and / or magnetic stirring. In these examples, the vortex may promote submersion of the chips and thereby melting of the chips.

[0035] In various embodiments, regardless of the type of furnace utilized for melting the chips, melting step 106 also may remove oxide layers from the surface of the chips during melting. In such embodiments, the oxide layers may be removed by adding salt flux to the first furnace and / or with the submersion of the chips within the first furnace. In various embodiments, once the chips are melted and the oxide layer is removed, the molten metal may be drained from the first furnace as the initial melt, thereby leaving behind the oxide and remnant melt, which is also known as white dross.

[0036] In certain embodiments, melting step 106 optionally includes processing the dross from the chips (e.g., to further recover aluminum and / or to remove salt from the dross). In various embodiments, processing the dross may include processing the white dross within the first furnace by adding salt flux and increasing the temperature of the first furnace. In some embodiments, processing the white dross may include increasing the temperature to be at orPatent Application Attorney Docket #: 108050-1483284 above 400 °C, such as at or above 700 °C, such as at or above 730 °C. The increased temperatures and the salt flux may separate the remnant melt from the oxide of the white dross. The remnant melt may be drained from the first furnace (and optionally provided with the initial melt), leaving behind a mixture of salt, oxides, and the metal, which is also known as black dross. In some embodiments, processing the dross may include processing the black dross by increasing the temperature of the first furnace above 1400 °C with excessive oxygen to evaporate the salt and to form inert oxides. In this example, the evaporated salt may be condensed from the off-gas and optionally collected for re-use, and the inert oxides in the first furnace may be reclaimed and / or transferred for other applications.

[0037] In summary, melting step 106 includes melting the chips in a first furnace and controlling salt flux to remove oxides and optionally process dross. Optionally, melting step 106 includes using organic material or lubricant on the chips as fuel for melting the chips.

[0038] Metal treatment step 108 is utilized to clean the initial melt from step 106 to achieve a desired metal quality and property specification for aerospace applications. As non-limiting examples, the initial melt from step 106 may include impurities such as solute elements and inclusions such as oxides, carbides, and borides, and metal treatment step 108 may remove such impurities and inclusions to provide the desired metal quality before casting.

[0039] Optionally, metal treatment step 108 includes transferring the initial melt from the first furnace used for melting step 106 to a second furnace such as but not limited to a transport crucible, melter, and / or other second furnace as desired. In certain embodiments, a volume of the second furnace may be less than a volume of the first furnace used for melting step 106, although it need not in other embodiments.

[0040] Metal treatment step 108 may include filtering the initial melt using an intermediate filter to produce an intermediate melt. In certain embodiments, the intermediate filter may remove coarse particles from the initial melt to produce the intermediate melt. Various filters may be utilized as the intermediate filter, such as but not limited to a ceramic foam filter. In various embodiments, the intermediate filter may have an intermediate porosity from about 10 ppi to about 30 ppi, such as about 10 ppi, about 15 ppi, about 20 ppi, about 25 ppi, and / or 30 ppi. In one non-limiting example, the intermediate filter may have a porosity of at least 10 ppi. Filters with other porosities may be utilized as desired as the intermediate filter.Patent Application Attorney Docket #: 108050-1483284

[0041] In various embodiments, metal treatment step 108 includes cleaning the intermediate melt. In certain embodiments, cleaning the intermediate melt may include using argon (Ar), nitrogen (N2), chlorine (Cl2), salt flux, or any combination thereof.

[0042] After cleaning of the intermediate melt, metal treatment step 108 may include purifying the intermediate melt to remove zirconium (Zr), vanadium (V), chromium (Cr), and / or titanium (Ti) elements. In some embodiments, purifying the intermediate melt may include adding boron (B) to the melt and precipitating the compounds. In other embodiments, other purifying techniques may be utilized as desired.

[0043] In certain embodiments, after cleaning and purifying the intermediate melt, metal treatment step 108 includes conducting density separation of the intermediate melt. In some embodiments, conducting density separation (also generally known as “settling”) may include holding the intermediate melt at a fixed temperature for a holding time such that particles less dense than molten aluminum or aluminum alloy (e.g., particles with a density less than from about 2. g / cm3to about 3 g / cm3, such as about 2.3 g / cm3to about 2.7 g / cm3, such as but not limited to dross, oxides, etc.) float while particles more dense than molten aluminum or aluminum alloy settle to at the bottom of the second furnace. In other words, heavier particles will settle to the bottom, and lighter particles will float to the surface, and the particular density may depend on the alloy.

[0044] Metal treatment step 108 may include skimming the surface of the intermediate melt after density separation to remove the floating particles, dross, and oxides. In certain embodiments, skimming the surface optionally may include utilizing a robotic arm, fork, or other suitable device or mechanism to remove the floating particles, dross, and oxides from the surface.

[0045] After skimming, metal treatment step 108 includes filtering the intermediate melt using a fine filter to produce a filtered melt. Similar to the intermediate filter, the fine filter may be various types of filters as desired, such as but not limited to a ceramic foam filter. In various embodiments, a porosity of the fine filter is smaller than that of the intermediate filter to remove finer particles compared to the intermediate filter. As non-limiting examples, the porosity of the fine filter may be about 30 ppi to about 80 ppi, such as about 30 ppi, about 35 ppi, about 40 ppi, about 45 ppi, about 50 ppi, about 55 ppi, about 60 ppi, about 65 ppi, about 70 ppi, about 75 ppi, and / or about 80 ppi. In one non-limiting example, the fine filter may have a porosity of at least 30 ppi. Filters with other porosities may be utilized as desired as the fine filter.Patent Application Attorney Docket #: 108050-1483284

[0046] In certain embodiments, the chemistry and / or inclusion level of the filtered melt may be monitored and / or determined. In some embodiments, the determined chemistry and / or inclusion level may be compared to a target or desired chemistry and / or inclusion level. In certain embodiments, the steps of intermediate filtering, cleaning, purifying, conducting density separation, skimming, and fine filtering may be repeated until the determined chemistry and / or inclusion level are acceptable and / or within thresholds of the target levels, thereby indicating that the filtered melt is a cleaned melt. Holding

[0047] After metal treatment step 108, the process 110 optionally includes holding step 110 in which the cleaned melt is maintained until it is turned into an ingot. In some embodiments, holding step 110 optionally includes transferring the cleaned melt to another melter or second furnace.

[0048] Holding step 110 may include casting the cleaned melt into a sow. In certain embodiments, casting the cleaned melt into the sow includes controlling a flow of metal during the transfer of the cleaned melt into a crucible or sow mold. Controlling the flow of metal during the transfer in turn may control turbulence, cold folds, cracks, shrinkage cavities, and / or additional inclusions. Optionally, controlling the flow of metal during the transfer includes utilizing a cover gas to prevent further oxidation during casting into the sow.

[0049] In various embodiments, holding step 110 includes skimming the surface of the cleaned melt after the transfer into the crucible or sow mold and controlling a cooling during solidification of the sow.

[0050] During the casting and product manufacturing step 112, recycled ingots and / or rolled products are produced from the sow of holding step 110 and / or directly from the cleaned melt of step 108. In certain embodiments, step 112 includes adding 10-100% of the cleaned melt to a fresh alloy made from prime aluminum by either remelting the sow or transferring the cleaned melt directly to a second furnace.

[0051] The casting step 112 may include conventional direct chill casting processes and / or product manufacture processes to produce aerospace rolled products and machined parts fromPatent Application Attorney Docket #: 108050-1483284 the recycled aerospace aluminum chips. As non-limiting examples, step 112 may include performing alloy correction after adding the cleaned melt to the fresh alloy, injecting gas or salt into the melt for further correction of sodium and hydrogen and / or removal of insoluble inclusions, skimming the melt surface, and transferring the melt to a trough. Casting step 112 may include adding grain refiner and oxide modifier during the metal transfer, degassing the melt with chlorine and / or argon gas, and filtering the melt with a ceramic foam filter before direct chill casting a recycled ingot. The aforementioned examples of processes that may be performed as part of step 112 should not be considered limiting, and various sub-combinations and / or additional processes may be utilized as desired

[0052] After casting step 112, various downstream processes and / or product manufacture processes may be performed in downstream processing step(s) 114 to produce aerospace rolled products and machined parts from the recycled aerospace aluminum chips. Thus, while a single downstream processing step 114 is illustrated, any number of downstream processing steps 114 may be utilized depending on a desired product. As non-limiting examples, downstream processing step 114 may include one or more of performing homogenization heat treatment, scalping, hot rolling cold rolling, stretching, solution heat treatment, and / or artificial aging of the recycled ingot, combinations thereof, and / or other processes as desired. The aforementioned examples of processes that may be performed as part of downstream processing step 114 should not be considered limiting, and various sub-combinations and / or additional processes may be utilized as desired to produce aerospace products and parts from the recycled chips.

[0053] The following Examples 1-3 are non-limiting examples recycling processes based on different input aerospace aluminum chips are provided below. Examples 1-3 are for illustrative purposes only, and other steps and / or combinations of steps may be utilized as desired to recycle the aerospace aluminum chips.

[0054] In a first non-limiting example, the input material received in step 102 includes wet compact chips.

[0055] In this example, the wet compact chips are subjected to a pretreatment step 104 that includes naturally drying the chips, breaking the compact into pieces of broken compact,Patent Application Attorney Docket #: 108050-1483284 magnetically separating the chips, shredding the chips (e.g., magnetically, mechanically, etc.), sieving the chips, and centrifuging, heating, or washing the chips.

[0056] After pretreatment step 104, the process includes melting the now-dry chips using a rotary furnace, crucible furnace, induction furnace, or sidewell furnace and removing oxides from the melt in melting step 106 to form the initial melt.

[0057] In this example, the process includes cleaning the initial melt in metal treatment step 108 by transferring the initial melt to a second furnace, filtering the initial melt with an intermediate filter having a porosity of 10 ppi to produce a filtered melt, cleaning the filtered melt, purifying the filtered melt, conducting density separation of the filtered melt, skimming the filtered melt, and filtering the filtered melt with a fine filter having a porosity of 30 ppi. Metal treatment step 108 may be repeated until the chemistry and / or inclusion level of the filtered melt is acceptable and the filtered melt is a cleaned melt.

[0058] The process include transferring the cleaned melt to sow mold, skimming the surface of the metal, and cooling the cast in a controlled manner in holding step 110.

[0059] In a second non-limiting example, the input material received in step 102 includes wet compact chips.

[0060] In this example, no pretreatment step 104 is performed, and the wet compact chips are provided directly into a first furnace in melting step 106. Melting step 106 may include melting the wet compact chips using a rotary furnace or a single crucible furnace. In this example, organic material and lubricant on the wet compact chips may be used as fuel to melt the chips. Melting during melting step 106 further includes removing oxides from the melt to form the initial melt.

[0061] In this example, the process includes cleaning the initial melt in metal treatment step 108 by transferring the initial melt to a second furnace, filtering the initial melt with an intermediate filter having a porosity of 30 ppi to produce a filtered melt, cleaning the filtered melt, purifying the filtered melt, conducting density separation of the filtered melt, skimming the filtered melt, and filtering the filtered melt with a fine filter having a porosity of 60 ppi. Metal treatment step 108 may be repeated until the chemistry and / or inclusion level of the filtered melt is acceptable and the filtered melt is a cleaned melt.Patent Application Attorney Docket #: 108050-1483284

[0062] The process include transferring the cleaned melt to sow mold, skimming the surface of the metal, and cooling the cast in a controlled manner in holding step 110. Example 3 – Dry Loose Chips with Pretreatment

[0063] In a third non-limiting example, the input material received in step 102 includes dry loose chips.

[0064] In this example, the dry loose chips are subjected to a pretreatment step 104 that includes magnetically separating the chips, shredding the chips, and sieving the chips.

[0065] After pretreatment step 104, the process includes melting the chips using a rotary furnace, crucible furnace, induction furnace, or sidewell furnace and removing oxides from the melt in melting step 106 to form the initial melt.

[0066] In this example, the process includes cleaning the initial melt in metal treatment step 108 by transferring the initial melt to a second furnace, filtering the initial melt with an intermediate filter having a porosity of 10 ppi to produce a filtered melt, cleaning the filtered melt, purifying the filtered melt, conducting density separation of the filtered melt, skimming the filtered melt, and filtering the filtered melt with a fine filter having a porosity of 30 ppi. Metal treatment step 108 may be repeated until the chemistry and / or inclusion level of the filtered melt is acceptable and the filtered melt is a cleaned melt.

[0067] The process include transferring the cleaned melt to sow mold, skimming the surface of the metal, and cooling the cast in a controlled manner in holding step 110. Illustrations

[0068] A collection of exemplary embodiments is provided below, including at least some explicitly enumerated as an “Illustration” providing additional description of a variety of example embodiments in accordance with the concepts described herein. These illustrations are not meant to be mutually exclusive, exhaustive, or restrictive; and the disclosure not limited to these example illustrations but rather encompasses all possible modifications and variations within the scope of the issued claims and their equivalents.

[0069] Illustration 1. A method of recycling aerospace aluminum chips, the method comprising: subjecting the aerospace aluminum chips to a pretreatment by drying the aerospacePatent Application Attorney Docket #: 108050-1483284 aluminum chips at a temperature at or below 400 °C for a duration of less than or equal to 60 minutes to produced pretreated chips; melting the pretreated chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a cleaned melt, wherein the metal treatment comprises one or more of (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and (vi) filtering the skimmed intermediate melt using a fine filter; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt in liquid state.

[0070] Illustration 2. The method of any preceding or subsequent illustration or combination of illustrations, further comprising at least one of sorting the compacted aerospace aluminum chips before the pretreatement, segregating the loose aerospace aluminum chips before the pretreatment, and / or compacting the loose aerospace aluminum chips before the pretreatment.

[0071] Illustration 3. The method of any preceding or subsequent illustration or combination of illustrations, wherein the pretreatment further comprises at least one of: breaking the aerospace aluminum chips into pieces by at least one of magnetic separation, magnetic shredding, or mechanical shredding; or treating the aerospace aluminum chips to remove lubricant from the aerospace aluminum chips.

[0072] Illustration 4. The method of any preceding or subsequent illustration or combination of illustrations, wherein melting the pretreated chips comprises melting the pretreated chips using at least one of a rotary furnace, a single crucible furnace, an induction furnace, or a sidewell furnace.

[0073] Illustration 5. The method of any preceding or subsequent illustration or combination of illustrations, wherein melting the pretreated chips further comprises removing oxide layers from the pretreated chips by controlling an addition of salt flux.

[0074] Illustration 6. The method of any preceding or subsequent illustration or combination of illustrations, wherein melting the pretreated chips further comprises: processing white dross from the pretreated chips by draining the initial melt from a first furnace, adding salt flux to the first furnace, and increasing a temperature of the first furnace to be at or above 400 °C, such as at least 700 °C, such as at or above 730 °C, to separate an aluminum melt and oxide from the white dross; and processing the resulting black dross by draining the aluminum melt fromPatent Application Attorney Docket #: 108050-1483284 the first furnace and increasing the temperature of the first furnace to be at or above 1400 °C to evaporate salt and form inert oxides.

[0075] Illustration 7. The method of any preceding or subsequent illustration or combination of illustrations, wherein: the intermediate filter comprises a porosity from 10 to or 30 ppi; cleaning the intermediate melt comprising using at least one of argon, nitrogen, chlorine, salt flux, or a combination thereof; purifying the intermediate melt comprises removing zirconium, vanadium, chromium, and / or titanium elements; and / or the file filter comprises a porosity from 30 ppi to 80 ppi, such as 30 ppi,, 60 ppi, and / or 80 ppi.

[0076] Illustration 8. The method of any preceding or subsequent illustration or combination of illustrations, further comprising remelting the intermediate sow to produce remelted clean melt and casting the remelted clean melt into an ingot.

[0077] Illustration 9. A method of recycling aerospace aluminum chips, the method comprising: melting the aerospace aluminum chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a cleaned melt, wherein the metal treatment comprises one or more of: filtering the initial melt using an intermediate filter to produce an intermediate melt; cleaning the intermediate melt; purifying the intermediate melt; conducting density separation of the intermediate melt; skimming the intermediate melt; filtering the skimmed intermediate melt using a fine filter to produce a filtered melt; determining an inclusion level of the filtered melt; and / or repeating one or more of the steps of metal treatment until the inclusion level is at a target level, wherein the cleaned melt comprises the target level; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

[0078] Illustration 10. The method of any preceding or subsequent illustration or combination of illustrations, wherein the metal treatment further comprises transferring the initial melt from a first furnace to a second furnace.

[0079] Illustration 11. The method of any preceding or subsequent illustration or combination of illustrations, wherein the intermediate filter comprises a porosity of at least 10 ppi and the fine filter comprises a porosity of at least 30 ppi, or wherein the intermediate filter comprises a porosity of at least 30 ppi and the fine filter comprises a porosity of at least 60 ppi.

[0080] Illustration 12. The method of any preceding or subsequent illustration or combination of illustrations, wherein cleaning the intermediate melt comprises using argon, nitrogen, chlorine, salt flux, or a combination thereof.Patent Application Attorney Docket #: 108050-1483284

[0081] Illustration 13. The method of any preceding or subsequent illustration or combination of illustrations, wherein purifying the intermediate melt comprises removing zirconium, vanadium, chromium, and / or titanium elements.

[0082] Illustration 14. The method of any preceding or subsequent illustration or combination of illustrations, wherein purifying the intermediate melt comprises adding boron to the intermediate melt and precipitating any compounds formed.

[0083] Illustration 15. The method of any preceding or subsequent illustration or combination of illustrations, wherein conducting density separation of the intermediate melt is based on a density of 2 g / cm3to 2.9 g / cm3, such as from 2.3 g / cm3to 2.7 g / cm3.

[0084] Illustration 16. A method of recycling aerospace aluminum chips, the method comprising: subjecting the aerospace aluminum chips to a pretreatment to produced pretreated chips; melting the pretreated chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a clean melt, wherein the metal treatment comprises one or more of (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and (vi) filtering the skimmed intermediate melt using a fine filter; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

[0085] Illustration 17. The method of any preceding or subsequent illustration or combination of illustrations, wherein the pretreatment comprises extruding the aerospace aluminum chips to form a continuous extrusion as the pretreated chips, and wherein the method comprises continuously feeding the continuous extrusion to a first furnace.

[0086] Illustration 18. The method of any preceding or subsequent illustration or combination of illustrations, further comprising casting the cleaned melt to an ingot by adding 10-100% of the cleaned melt to a direct chill casting system.

[0087] Illustration 19. The method of any preceding or subsequent illustration or combination of illustrations, wherein solidifying the cleaned melt comprises transferring the cleaned melt to a second furnace; casting the clean melt into the intermediate sow using a sow mold; and skimming after the transfer into the sow mold.

[0088] Illustration 20. The method of any preceding or subsequent illustration or combination of illustrations, wherein transferring the cleaned melt comprises controlling metal flow during transfer and using a cover gas to control oxidation.Patent Application Attorney Docket #: 108050-1483284

[0089] Illustration 21. An ingot produced by the method of any preceding or subsequent illustration or combination of illustrations.

[0090] Illustration 22. The ingot of any preceding or subsequent illustration or combination of illustrations, wherein the ingot is a 7xxx series aluminum alloy and / or a 2xxx series aluminum alloy.

[0091] The subject matter of embodiments of the present disclosure is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. Directional references such as “up,” “down,” “top,” “bottom,” “left,” “right,” “vertical,” “horizontal,” “lateral,” “longitudinal,” “front,” and “back,” among others, are intended to refer to the orientation as illustrated and described in the figure (or figures) to which the components and directions are referencing.

[0092] The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, or gradients thereof, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention, and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0093] The above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of the presentPatent Application Attorney Docket #: 108050-1483284 disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed herein, as well as in the claims that follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described embodiments, nor the claims that follow.

Claims

Patent Application Attorney Docket #: 108050-1483284 CLAIMS That which is claimed:

1. A method of recycling aerospace aluminum chips, the method comprising: subjecting the aerospace aluminum chips to a pretreatment by drying the aerospace aluminum chips at a temperature at or below 400 °C for a duration of less than or equal to 60 minutes to produced pretreated chips; melting the pretreated chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a cleaned melt, wherein the metal treatment comprises one or more of (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and / or (vi) filtering the skimmed intermediate melt using a fine filter; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt while the cleaned melt is in liquid state.

2. The method of claim 1, further comprising segregating the loose aerospace aluminum chips before the pretreatment.

3. The method of claim 1, further comprising compacting the aerospace aluminum chips before the pretreatment.

4. The method of claim 1, further comprising sorting the compacted aerospace aluminum chips before the pretreatment.

5. The method of claim 1, wherein the pretreatment further comprises at least one of: breaking the aerospace aluminum chips into pieces by at least one of magnetic separation, mechanical shredding, or magnetic shredding; or treating the aerospace aluminum chips to remove lubricant from the aerospace aluminum chips.Patent Application Attorney Docket #: 108050-1483284 6. The method of claim 1, wherein melting the pretreated chips comprises melting the pretreated chips using at least one of a rotary furnace, a single crucible furnace, an induction furnace, or a sidewell furnace.

7. The method of claim 1, wherein melting the pretreated chips further comprises removing oxide layers from the pretreated chips by controlling an addition of salt flux.

8. The method of claim 1, wherein melting the pretreated chips further comprises: processing white dross from the pretreated chips by draining the initial melt from a first furnace, adding salt flux to the first furnace, and increasing a temperature of the first furnace to be at or above 700 °C to separate an aluminum melt and oxide from the white dross; and processing resulting black dross by draining the aluminum melt from the first furnace and increasing the temperature of the first furnace to be at or above 1400 °C to evaporate salt and form inert oxides.

9. The method of claim 1, wherein: the intermediate filter comprises a porosity from 10 ppi to 30 ppi; cleaning the intermediate melt comprising using at least one of argon, nitrogen, chlorine, salt flux, or a combination thereof; purifying the intermediate melt comprises removing zirconium, vanadium, chromium, and / or titanium elements; and / or the file filter comprises a porosity from 30 ppi to 60 ppi.

10. The method of claim 1, further comprising remelting the intermediate sow to produce remelted clean melt and casting the remelted clean melt into an ingot.

11. A method of recycling aerospace aluminum chips, the method comprising: melting the aerospace aluminum chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a cleaned melt, wherein the metal treatment comprises one or more of: (i) filtering the initial melt using an intermediate filter to produce an intermediate melt; (ii) cleaning the intermediate melt;Patent Application Attorney Docket #: 108050-1483284 (iii) purifying the intermediate melt; (iv) conducting density separation of the intermediate melt; (v) skimming the intermediate melt; (vi) filtering the skimmed intermediate melt using a fine filter to produce a filtered melt; (vii) determining an inclusion level of the filtered melt; and / or (viii) repeating steps (i)-(vii), or a sub-combination thereof, until the inclusion level is at a target level, wherein the cleaned melt comprises the target level; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

12. The method of claim 11, wherein the metal treatment further comprises transferring the initial melt from a first furnace to a second furnace before step (i).

13. The method of claim 11, wherein the intermediate filter comprises a porosity of at least 10 ppi and the fine filter comprises a porosity of at least 30 ppi, or wherein the intermediate filter comprises a porosity of at least 30 ppi and the fine filter comprises a porosity of at least 60 ppi.

14. The method of claim 11, wherein cleaning the intermediate melt comprises using argon, nitrogen, chlorine, salt flux, or a combination thereof.

15. The method of claim 11, wherein purifying the intermediate melt comprises removing zirconium, vanadium, chromium, and / or titanium elements.

16. The method of claim 11, wherein purifying the intermediate melt comprises adding boron to the intermediate melt and precipitating any compounds formed.

17. The method of claim 11, wherein conducting density separation of the intermediate melt is based on a density from 2 g / cm3to 2.9 g / cm3.

18. A method of recycling aerospace aluminum chips, the method comprising:Patent Application Attorney Docket #: 108050-1483284 subjecting the aerospace aluminum chips to a pretreatment to produced pretreated chips; melting the pretreated chips to obtain an initial melt; subjecting the initial melt to a metal treatment to produce a clean melt, wherein the metal treatment comprises one or more of (i) filtering the initial melt using an intermediate filter to produce an intermediate melt, (ii) cleaning the intermediate melt, (iii) purifying the intermediate melt, (iv) conducting density separation of the intermediate melt, (v) skimming the intermediate melt, and (vi) filtering the skimmed intermediate melt using a fine filter; and solidifying the cleaned melt into an intermediate sow or transferring the cleaned melt to a casting system.

19. The method of claim 18, wherein the pretreatment comprises extruding the aerospace aluminum chips to form a continuous extrusion as the pretreated chips, and wherein the method comprises continuously feeding the continuous extrusion to a first furnace.

20. The method of claim 18, further comprising casting the cleaned melt to an ingot by adding 10-100% of the cleaned melt to a direct chill casting system.

21. The method of claim 18, wherein solidifying the cleaned melt comprises: transferring the cleaned melt to a second furnace; casting the clean melt into the intermediate sow using a sow mold; and skimming after the transfer into the sow mold.

22. The method of claim 21, wherein transferring the cleaned melt comprises controlling metal flow during transfer and using a cover gas to control oxidation.

23. An ingot produced by the method of claim 1, 11, or 18.

24. The ingot of claim 23, wherein the ingot is a 7xxx series aluminum alloy or a 2xxx series aluminum alloy.

Images