Improved aluminum purification cells

Abstract

New aluminum purification cells are disclosed. An aluminum purification cell may include at least one cathode partially positioned within an electrolyte that is disposed above a molten metal pad. Aluminum ions may be produced within the electrolyte from aluminum of the molten metal pad and metallic aluminum may be produced from the aluminum ions at a surface of the at least one cathode. The metallic aluminum may be collected as purified aluminum metal within a liquid metal collector that at least partially surrounds a portion of the at least one cathode. The liquid metal collector may include at least one collector wall that defines a recessed collection region for collecting the purified aluminum metal.

Description

Attorney Ref. No.: 169593.120020 / WOIMPROVED ALUMINUM PURIFICATION CELLSCROSS REFERENCE TO RELATED APPLICATION|0001] This application claims priority to U. S. Provisional Patent Application No.63 / 723,483, entitled "‘Improved Aluminum Purification Cells,” filed November 21, 2024, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] Aluminum metal has been traditionally made by converting alumina (AI2O3), which typically originates from bauxite ore. The conversion of alumina to aluminum is typically carried out in an electrolytic cell by passing an electric current through an electrolyte having alumina and cry olite. Carbon from the carbon anode reacts with the oxygen component in the alumina to produce carbon dioxide, which is expelled from the cell, leaving molten aluminum. The molten aluminum gathers on the bottom of the electrolytic cell and is subsequently removed as relatively pure metallic aluminum. Various efforts have been made to purify metallic aluminum, including the “Hoopes process” (see U. S. Patent No. 1,534,315) as well as those methods described in commonly owned International Patent Application Publication No. WO2016 / 130823.SUMMARY OF THE DISCLOSURE

[0003] Broadly, the present disclosure relates to aluminum purification cells and methods pertaining to the same. The aluminum purification cell may be useful, for instance, in purifying a feedstock comprising metallic aluminum or aluminum alloys. In one embodiment, the feedstock may comprise aluminum scrap, which scrap may include metallic aluminum and / or one or more aluminum alloys. In one embodiment, an aluminum purification cell includes (a) an electrolyte disposed above a molten metal pad, (b) at least one cathode partially positioned within the electrolyte and a purified aluminum metal disposed on the electrolyte, and (c) a liquid metal collector surrounding at least a portion of the at least one cathode and configured to collect, within a collection region comprising the purified aluminum metal, metallic aluminum produced at a surface of the at least one cathode. Due to the collection of the purified aluminum metal, the liquid metal collector may restrict metallic aluminum metal from a sidewall and other regions of the aluminum purification cell outside the liquid metal collector.

[0004] These and other aspects, advantages, and novel features of this new technology are set forth in part in the description that follows and will become apparent to those skilled inAttorney Ref. No.: 169593.120020 / WQthe art upon examination of the following description and figures, or may be learned by practicing one or more embodiments of the technology provided for by the present disclosure.BRIEF DESCRIPTION OF DRAWINGS

[0005] FIG. l is a process flow diagram illustrating one embodiment of a method for purifying aluminum in accordance with the present disclosure.

[0006] FIG. 2 is a cross-sectional side view of one embodiment of an aluminum purification cell in accordance with the present disclosure.

[0007] FIG. 3 is a cross-sectional side view of one embodiment of an aluminum purification cell in accordance with the present disclosure.

[0008] FIG. 4 is a cross-sectional side view of one embodiment of an aluminum purification cell in accordance with the present disclosure.

[0009] FIG. 5 is a cross-sectional side view of one embodiment of an aluminum purification cell in accordance with the present disclosure.

[0010] FIG. 6 is a cross-sectional side view of one embodiment of an aluminum purification cell in accordance with the present disclosure.DETAILED DESCRIPTION OF DRAWINGS

[0011] As noted above, the present disclosure relates to aluminum purification cells and methods pertaining to the same, and, in particular, metal collection features relating to aluminum purification cells and methods of collecting metal in aluminum purification cells.I. Methods of Making Purified Aluminum

[0012] In one approach, an aluminum purification cell includes at least one cathode in fluid communication with an electrolyte and at least one anode in spaced relation from the at least one cathode and also in fluid communication with the electrolyte. In one embodiment, the electrolyte includes aluminum ions. The aluminum ions may be reduced, resulting in formation of molten metallic aluminum. Due to a density difference between the electrolyte and the metallic aluminum, a molten metal layer of metallic aluminum may form proximal the electrolyte. In one embodiment, the molten metal layer is less dense than the electrolyte and thus forms above or on top of the electrolyte. In another embodiment, the molten metal layer is denser than the electrolyte and thus forms below or under the electrolyte. The molten metal layer may be periodically removed from the aluminum purification cell, such as by tapping.

[0013] One non-limiting embodiment of an exemplary’ method for purifying aluminum is illustrated in FIG. 1. In the illustrated embodiment, the method comprises producing (1000) aluminum ions in an electrolyte from aluminum-based feedstock. The aluminum ions may beAttorney Ref. No.: 169593.120020 / WQformed in an aluminum purification cell that includes at least one cathode. The aluminum purification cell may include a molten aluminum pad that includes molten aluminum along with impurities and / or densifying aids. The aluminum purification cell may also include at least one anode that is positioned in the molten aluminum pad and extends into the electrolyte, which is located above the molten aluminum pad. The at least one anode may partially overlap the at least one cathode in the electrolyte. The aluminum ions may be produced in the electrolyte by supplying an electric current to the anodes, with the electric current being removed at the cathodes of the aluminum purification cell. Without being bound by any particular mechanism or theory, it is believed that the anode facilitates an electrochemical reaction, such that the aluminum metal with impurities is anodized to aluminum ions Al3+(transported to the electrolyte) such that impurities are left behind on the anode. Then, the aluminum ions are reduced on the cathode surface and form aluminum metal, where the metal is in purified form, since the impurities remained on the anode surface and / or were collected in the metal pad (e.g. given density of the impurities vs. the electrolyte / bath components).

[0014] The method additionally comprises forming (2000) metallic aluminum at a cathode in the electrolyte. The metallic aluminum may be formed on at least one cathode, where the aluminum ions are reduced onto a surface of the at least one cathode and form aluminum metal, the aluminum metal being in purified form. Metallic aluminum may remain on or near a surface of the at least one cathode and / or may be present within the electrolyte in regions separate from the at least one cathode.

[0015] The method further comprises collecting (3000) metallic aluminum in a collection region above the electrolyte. The aluminum purification cell may include a liquid metal collector that at least partially surrounds a portion of the at least one cathode. The liquid metal collector may be disposed at least partially in the electrolyte and may include collector walls that surround a recessed collection region for collecting metallic aluminum produced in the electrolyte. In one embodiment, the metallic aluminum may move in an upward direction along the at least one cathode and / or through the electrolyte due to a buoyancy of the metallic aluminum in the electrolyte. The metallic aluminum may be collected in a layer of purified aluminum metal that is located above the electrolyte. The collector walls of the liquid metal collector may separate the collected purified aluminum metal from regions of the aluminum purification cell surrounding the liquid metal collector to restrict accumulation of metallic aluminum in the surrounding regions. By restricting accumulation of metallic aluminum in a region between the cathode and a “hot” sidewall (i.e., a sidewall that carries an anodic charge) of the aluminum purification cell, the liquid metal collector may prevent the formation of aAttorney Ref. No.: 169593.120020 / WQdirect electrical path between the cathode and the sidewall that could produce an electrical short in the aluminum purification cell. Additionally, the liquid metal collector may restrict or prevent molten aluminum from being oxidized by the atmosphere and may facilitate extraction of purified aluminum metal from the aluminum purification cell by collecting the purified aluminum metal in the collection region.

[0016] In one embodiment, the collecting step (3000) comprises conveying at least a portion of the metallic aluminum along a surface, such as an inner collector wall surface, of the liquid metal collector toward the collection region. In one embodiment, at least a portion of the metallic aluminum is conveyed along a sloped portion of the surface of the liquid metal collector that slopes toward the collection region. In one embodiment, at least a portion of the metallic aluminum is conveyed along a vertical portion of the surface of the liquid metal collector. In one embodiment, the method comprises restricting, by the liquid metal collector, migration of the metallic aluminum from the electrolyte to a region surrounding an outer surface of the liquid metal collector. In one embodiment, the method comprises wetting a surface of a wettable element with metallic aluminum, wherein the wettable element is located on a peripheral portion of the liquid metal collector between the collection region and the sidewall of the aluminum purification cell. In one embodiment, the method comprises removing at least a portion of the purified aluminum metal from the collection region to a location outside the aluminum purification cell. In one embodiment, the method comprises adding additional aluminum-based feedstock to a region of the aluminum purification cell near the molten pad.II. Aluminum Purification Cells

[0017] Referring now to FIG. 2, one embodiment of an aluminum purification cell is illustrated. In the illustrated embodiment, the aluminum purification cell (100) includes a cell bottom (104) and sidewalls (106), In some embodiments, the aluminum purification cell (100) may include thermal insulation (not shown) surrounding at least a portion of cell bottom (104) and / or sidewalls (106) to facilitate high energy efficiency of the aluminum purification cell (100) and / or to decrease heat loss from interior regions of the aluminum purification cell (100).

[0018] The aluminum purification cell (100) includes at least one anode (112), such as first and second anodes (112i) and (112.2). In the illustrated embodiment of FIG. 2, first and second anodes (112₁) and (112₂) comprise elongate vertical anodes extending upward from the cell bottom (104). Any other suitable shape, size, configuration, and / or number of anodes (112) may be included in the aluminum purification cell (100). In one embodiment, an end of theAttorney Ref. No.: 169593.120020 / WOfirst anode (112i) and / or the second anode (1122) may be connected to an upper surface of the cell bottom (104) and / or may be at least partially embedded in the cell bottom (104), e.g., via one or more holes or apertures located in the cell bottom (104). One or more of the first anode (1121) and / or the second anode (112?.) may extend through a molten metal pad (108). In some embodiments, the first anode (112i) and / or the second anode (112s) may partially extend into an electrolyte (110) disposed above the molten metal pad (108). In one embodiment, the first anode (112i) and / or the second anode (1122) may be monolithic.

[0019] In some embodiments, the first and second anodes (112i) and (112?.) are electrically connected to an external power source that supplies an anodic current (e.g., a positively charged current) to the first and second anodes (112i) and ( 1122). For example, one end of an anode connector may be coupled to the external power source and an opposite end of the anode connector may be in electrical communication with the first and second anodes (112i) and (1122) either directly or through the cell bottom (104). Accordingly, the cell bottom (104) may include an electrically conductive material (e.g., graphite) configured to transmit electrical current to the first and second anodes (112i) and (1122.) and or to the molten metal pad (108).

[0020] In some embodiments, the first anode (112i) and the second anode (1122) are aluminum-wettable. As used herein, “aluminum-wettable” means having a contact angle with molten aluminum of not greater than 90 degrees. In some embodiments, the first anode (112i) and / or the second anode (1122) may comprise a boride material (e.g., one or more of borides of titanium, zirconium, and / or hafnium), a carbonaceous material, tungsten (W), molybdenum (Mo), steel, and combinations thereof. In some embodiments, the first anode (112i) and / or the second anode (112.2) comprises or consists essentially of titanium diboride (TiB2). In some embodiments, the first anode (112i) and / or the second anode (1122) is non-consumable (e.g., when made of a non-carbonaceous material, such as a boride material). In some embodiments, the first anode (112₁) and / or the second anode (112₂) is consumable (e.g., when made of a carbonaceous material). In one embodiment, an elongate vertical anode is configured to be wettable by tire molten metal pad (108). In one embodiment, the wetting metal comprises aluminum. In one embodiment, the first anode (112i) and / or the second anode (112?.) may include a base material (e.g., graphite or carbon) coated with an aluminum wettable material (e.g. a boride of titanium, zirconium, and / or hafnium). The aluminum wettable coating may cover a portion of (e.g., a majority of) or all of the base material.

[0021] In some embodiments, the aluminum purification cell (100) may include at least one cathode, such as cathode (114) illustrated in FIG. 2. The cathode (114) may comprise anAttorney Ref. No.: 169593.120020 / WQelongate vertical cathode extending downward from an upper portion of the aluminum purification cell (100). Any other suitable shape, size, configuration, and / or number of cathodes (114) may be included in the aluminum purification cell (100). In the illustrated embodiment, the cathode (114) may extend through a layer of purified aluminum metal (116) disposed on top of the electrolyte (110). In some embodiments, the cathode (114) may partially extend into the electrolyte (110) disposed below the purified aluminum metal (116). In one embodiment, the cathode (114) may be monolithic. In some embodiments, the cathode (114) is electrically connected to an external power source that supplies a cathodic current (e.g., a negatively charged current) to the cathode (114). For example, one end of a cathode connector may be coupled to the external power source and an opposite end of the cathode connector may be in electrical communication with the cathode (114). At least one of the cathode and the cathode connector may pass through a portion of the liquid metal collector (120), such as through the collector top (122).

[0022] In some embodiments, tire cathode (114) comprises a solid material that is aluminum-wettable. In some embodiments, the cathode (114) may comprise a non-carbonaceous material, such as a boride material (e.g., one or more borides of titanium, zirconium, and / or hafnium), a carbonaceous material, and combinations thereof. In some embodiments, the cathode (114) comprises or consists essentially of titanium diboride (TiB₂). In some embodiments, the cathode (114) is non-consumable (e.g., when made of a boride material). In some embodiments, the cathode (114) is consumable (e.g., when made of a carbonaceous material). In one embodiment, the cathode (114) is configured to be wettable by metal. In one embodiment, the wetting metal comprises aluminum. In one embodiment, the cathode (114) comprises a base material (e.g., graphite or carbon) coated with an aluminum wettable material (e.g. a boride of titanium, zirconium, and / or hafnium). The aluminum wettable coating may cover a portion of (e.g., a majority of) or all of the base material.

[0023] In the illustrated embodiment of FIG. 2, the cathode (114) comprises an elongate vertical cathode that overlaps at least one an elongate vertical anode (112), such as the first and second anodes (112i) and (1122). In some embodiments, the anode-cathode overlap (ACO) betw een the at least one anode (112) and the at least one cathode (114) is configured to lower the voltage requirements of the cell, lower tire energy consumption of the cell, and / or achieve a proper thermal balance of the cell. As used herein, "‘anode-cathode overlap” (ACO) means the vertical distance from a distal end of an anode (e.g., an elongate vertical anode) and a distal end of a respective cathode (e.g., an adjacent elongate vertical cathode). In some embodiments, the ACO between the at least one anode (112) and the at least one cathode (114)Attorney Ref. No.: 169593.120020 / WOis from 0 to 50 inches. In some embodiments, the ACO is from 1 to 50 inches. In some embodiments, the ACO is from 5 to 50 inches. In some embodiments, the ACO is from 10 to 50 inches. In some embodiments, the ACO is from 20 to 50 inches. In some embodiments, the ACO is from 25 to 50 inches. In some embodiments, the ACO is at least some overlap up to 12 inches of overlap. In some embodiments, the ACO is at least 2 inches of overlap to 10 inches of overlap. In some embodiments, the ACO is at least 3 inches of overlap to 8 inches of overlap. In some embodiments, the ACO is at least 3 inches of overlap to 6 inches of overlap.

[0024] One or more inert spacers (not illustrated) may be located proximal (e.g., in between) one or more cathode(s) (114) and one or more anode(s) (112) to maintain a desired anode to cathode distance (ACD), The inert spacers may be of any suitable inert material (e.g., alumina, nitrides, carbonaceous materials, such as graphite) and may be of any suitable size and shape. The inert spacers may be placed as necessary in the cell to achieve the appropriate ACD. As used herein, "‘anode to cathode distance” (ACD) means the horizontal distance separating an anode (e.g., an elongate vertical anode) from a respective cathode (e.g., an adjacent elongate vertical cathode). In some embodiments, the ACD may be from 1 / 8 inch to 3 inches. In some embodiments, tire ACD may be from 1 / 8 inch to 2 inches. In some embodiments, the ACD may be from 1 / 8 inch to 1 inch. In some embodiments, the ACD may be from 1 / 8 inch to 1 / 4 inch. In some embodiments, the ACD may be from 1 / 4 inch to 1 / 2 inch. In some embodiments, the ACD may be from 1 / 8 inch to 3 / 4 inch. In some embodiments, the ACD may be from 1 / 8 inch to 1 inch. In some embodiments, the ACD may be from 1 / 8 inch to 1 / 2 inch.

[0025] The cell side walls (106) and the cell bottom (104) at least partially define a cell chamber (118) within the aluminum purification cell (100). In some embodiments, the cell sidewalls (106) may be made of a heat-stable material (e.g., a refractory material) that is generally inert to the liquid / molten conditions of the aluminum purification cell (100). In some embodiments, the cell chamber (118) contains: a molten metal pad (108) or zone, an electrolyte (110) layer or zone, and a purified aluminum metal (116) layer or zone. The molten metal pad (108) may be in con tact with the cell bottom (104) of the aluminum purification cell (100). In the illustrated embodiment, the electrolyte (110) separates the purified aluminum metal (116) from the molten metal pad (108). In the illustrated embodiment, one or more of the anodes (112) extend upward from the cell bottom (104), through the molten metal pad (108) and terminate in the electrolyte (110). The at least one cathode (114) extends downward through the purified aluminum metal (116) and terminates in the electrolyte (110). In tire illustrated embodiment, the at least one cathode (114) overlaps with one or more of the anodes (112)Attorney Ref. No.: 169593.120020 / WOwithin the electrolyte (110). Thus, the at least one cathode (114) is separated from the at least one anode (112) by the electrolyte (110).

[0026] As described above, in the illustrated embodiment, the electrolyte (110) separates the purified aluminum metal (116) from the molten metal pad (108). As used herein, “electrolyte” means a medium in which the flow of electrical current is carried out by the movement of ions / ionic species. In one embodiment, an electrolyte may comprise one or more molten salts. In one embodiment, a composition of the electrolyte (110) may be selected such that the electrolyte (110) has a lower density than the molten metal pad (108) and a higher density than tire purified aluminum metal (116). In some embodiments, the electrolyte (110) may comprise salts of at least one fluoride and / or chloride. In one embodiment, a cation of fluoride salts and / or chloride salts includes at least one of lithium (Li), sodium (Na), potassium (K), aluminum (Al), barium (Ba), calcium (Ca), magnesium (Mg), cerium (Ce), lanthanum (La), cesium (Cs), rubidium (Rb), and combinations thereof, among others. In one embodiment, the electrolyte (110) comprises at least one of BaF₂ and AlF₃. In one embodiment, the electrolyte (110) comprises from 5 wt. % to 70 wt. % BaF₂. In another embodiment, the electrolyte (110) comprises from 0.5 to 30 wt. % AlF₃. In yet another embodiment, the electrolyte (110) comprises from 5 to 70 wt. % BaF₂ and from 0.5 to 30 wt. % AlF₃. In one embodiment, the electrolyte (110) also includes at least one of LaF₃, KF, MgF₂, and NaF in addition to at least one of BaF₂ and AlF₃.

[0027] The aluminum purification cell (100) may be operated at any suitable temperature. In one embodiment, a temperature of the electrolyte is from 700 to 980 degrees Celsius. In one embodiment, a temperature of the electrolyte (110) is at least 750 degrees Celsius. In another embodiment, a temperature of the electrolyte (110) is at least 800 degrees Celsius, In another embodiment, a temperature of the electrolyte (110) is at least 850 degrees Celsius. In another embodiment, a temperature of the electrolyte (110) is at least 900 degrees Celsius. In one embodiment, a temperature of the electrolyte (110) is not greater than 970 degrees Celsius. In another embodiment, a temperature of the electrolyte (110) is not greater than 960 degrees Celsius. In another embodiment, a temperature of the electrolyte (110) is not greater than 950 degrees Celsius. In one embodiment, a temperature of the electrolyte (110) is from 900 to 950 degrees Celsius.

[0028] As used herein, “purified aluminum” means a material having at least 95.0 wt, % aluminum, which aluminum is in metallic or alloyed form. In one embodiment, a purified aluminum material includes at least 96.0 wt. % aluminum. In another embodiment, a purified aluminum material includes at least 97.0 wt. % aluminum. In yet another embodiment, aAttorney Ref. No.: 169593.120020 / WQpurified aluminum material includes at least 97.5 wt. % aluminum. In another embodiment, a purified aluminum material includes at least 98.0 wt. % aluminum. In yet another embodiment, a purified aluminum material includes at least 98.5 wt. % aluminum. In another embodiment, a purified aluminum material includes at least 99.0 wt. % aluminum. In yet another embodiment, a purified aluminum material includes at least 99.5 wt. % aluminum. In another embodiment, a purified aluminum material includes at least 99.6 wt, % aluminum. In yet another embodiment, a purified aluminum material includes at least 99.7 wt. % aluminum. In another embodiment, a purified aluminum material includes at least 99.8 wt. % aluminum. In yet another embodiment, a purified aluminum material includes at least 99.9 wt. % aluminum, or more. In one embodiment, the purified aluminum is in the form of a molten metal layer of an aluminum purification cell. In one embodiment, the purified aluminum is in the form of a solid material, e.g., a material formed due to extraction of the molten metal layer of the aluminum purification cell.

[0029] In some embodiments, the purified aluminum metal (116) has 99.5 wt. % to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.6 wt. % to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99,7 wt, %to 99.999 wt, % aluminum. In some embodiments, the purified aluminum metal (116) has 99.8 wt. %to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.9 wt. % to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.95 wt. % to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.98 wt. % to 99.999 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.5 wt. % to 99.99 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.5 wt. % to 99.95 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.5 wt. % to 99.9 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99,5 wt. %to 99.8 wt. % aluminum. In some embodiments, the purified aluminum metal (116) has 99.5 wt. %to 99.7 wt, % aluminum,

[0030] As noted previously, a molten metal pad may be located within an aluminum purification cell. In one embodiment, a molten metal pad (108) may include aluminum and impurities (e.g., from 1-80 wt. % impurities, or more). In one embodiment, the impurities of the molten metal pad at least partially assist in providing a suitable density to the molten metal pad (e.g., so the molten metal pad is located below an electrolyte). A molten metal pad may comprise any suitable elements as impurities, including, by way of example, silicon (Si), copper (Cu), iron (Fe), antimony (Sb), gadolinium (Gd), cadmium (Cd), tin (Sn), lead (Pb),Attorney Ref. No.: 169593.120020 / WOmagnesium (Mg), zinc (Zn), titanium (Ti), and / or boron (B). A molten metal pad may be located near or below an electrolyte of an aluminum purification cell. In one embodiment, an aluminum purification cell includes a top layer, a middle layer, and a bottom layer. In one embodiment, the top layer is a purified aluminum metal (116) layer, the middle layer is an electrolyte (110) layer, and the bottom layer is a molten metal pad (108). The top layer is generally less dense than the middle layer, and the middle layer is generally less dense than the bottom layer.

[0031] In one embodiment, the molten metal pad (108) comprises aluminum. In one embodiment, the molten metal pad (108) comprises at least 20 wt. % Al. In one embodiment, the molten metal pad (108) comprises at least 25 wt. % Al. In another embodiment, the molten metal pad (108) comprises at least 30 wt. % Al. In yet another embodiment, the molten metal pad (108) comprises at least 35 wt. % Al. In another embodiment, the molten metal pad (108) comprises at least 40 wt. % Al, In yet another embodiment, the molten metal pad (108) comprises at least 45 wt. % Al. In another embodiment, the molten metal pad (108) comprises at least 50 wt. % Al. In yet another embodiment, the molten metal pad (108) comprises at least 55 wt. % Al. In another embodiment, the molten metal pad (108) comprises at least 60 wt. % Al, In yet another embodiment, the molten metal pad (108) comprises at least 65 wt. % Al. In another embodiment, the molten metal pad ( 108) comprises at least 70 wt. % Al. In yet another embodiment, tire molten metal pad (108) comprises at least 75 wt. % Al. In another embodiment, the molten metal pad (108) comprises at least 80 wt. % Al. In one embodiment, the molten metal pad (108) comprises copper (Cu), which may be present in aluminum feedstock used to produce the molten metal pad (108) and / or which may be added to the molten metal pad (108) as a densifying aid. In one embodiment, the molten metal pad (108) comprises at least 0.3 wt. % Cu, In one embodiment, the molten metal pad (108) comprises from 1 to 60 wt.% Cu.

[0032] In some embodiments, the aluminum purification cell (100) may include an outer shell (not shown), which may comprise steel or other suitable materials. In some embodiments, the outer shell may include a shell floor located beneath the cell bottom (104) and / or shell sidewalls spaced apart from and at least partially surrounding the cell sidewalls (106). Thermal insulation may be located in a region between the outer shell and cell bottom (104) and / or cell sidewalls (106). The thermal insulation may facilitate high electrical and heat transfer efficiency of the aluminum purification cell (100).

[0033] One embodiment of a method for purifying aluminum includes supplying an electric current to the at least one anode (112) and to the molten metal pad (108). MoltenAttorney Ref. No.: 169593.120020 / WOmaterial (including molten aluminum) from the molten metal pad (108) may move along the vertical surfaces of the vertical anodes (112i and 1122) in an upward direction. In some embodiments, the upward movement of the mol ten material from the mol ten metal pad (108) may occur continuously during operation of the aluminum purification cell (100). in some embodiments, molten material from the molten metal pad (108) may cover some, all, or essentially all of the exposed surfaces of the anodes ( 112i and 1122), Molten aluminum on the surface of the anodes (112: and 1122) may be oxidized thereby producing aluminum ions (i.e., Al3+). In some embodiments, molten aluminum at the surface of the molten metal pad (108) contacting the electrolyte (110) may also be oxidized so as to produce aluminum ions in the electrolyte (110). At least some of the aluminum ions may be transported through the electrolyte (110) onto surfaces of the cathode(s) (114) positioned within the electrolyte (110). At least some of the aluminum ions in the electrolyte (110) may be reduced via electrical current at the cathode(s) (114), thereby producing metallic aluminum (i.e., purified aluminum metal) on the surfaces of the cathode(s) (114) and / or within the electrolyte (110). Without being bound by a particular mechanism or theory, it is hypothesized that at least some of the metallic aluminum moves along surface(s) of the cathode(s) (114) in an upward direction due to a buoyancy of the purified aluminum metal in the electrolyte (110), In some embodiments, at least some of the purified metallic aluminum within the electrolyte (110) may also collect in droplets that move upward through electrolyte (110) to the layer of purified aluminum metal (116) due to buoyancy of the metallic aluminum in the electrolyte (110). Thus, the purified aluminum metal (116) may tend to collect as atop layer above the electrolyte (110). Based on differences in density between the purified aluminum metal (116), the electrolyte (110), and the molten metal pad (108) (e.g., including feedstock with aluminum metal, impurities, and / or densifying aids, such as Cu and / or other additives included to increase density), the molten metal pad (108) is configured to have a density greater than the electrolyte (110), with the molten metal pad (108) disposed below the electrolyte (110).

[0034] In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 1 to 15 kWh / kg of purified aluminum metal (116). As used herein, "‘energy efficiency” means the amount of energy (in kilowatt hours) consumed by an aluminum purification cell per kilogram of purified aluminum metal produced by the aluminum purification cell. In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 1 to 10 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at anAttorney Ref. No.: 169593.120020 / WQenergy efficiency of 1 to 8 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 1 to 6 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 1 to 4 kWh / kg of purified aluminum metal (116).

[0035] In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 5 to 15 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 10 to 1 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 12 to 15 kWh / kg of purified aluminum metal (116).

[0036] In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 2 to 10 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may be produced via the aluminum purification cell (100) at an energy efficiency of 2 to 8 kWh / kg of purified aluminum metal (116). In some embodiments, the purified aluminum metal (116) may¬ be produced via the aluminum purification cell (100) at an energy efficiency of 2 to 6 kWh / kg of purified aluminum metal (116).

[0037] In some embodiments, aluminum feedstock may be added to the molten metal pad (108) continuously, essentially continuously, or periodically during operation of the aluminum purification cell (100). As used herein, “-aluminum feedstock” means a feedstock having metallic aluminum and / or one or more aluminum alloys. The aluminum feedstock may include, for instance aluminum scrap, primary aluminum, and / or secondary aluminum. In one embodiment, an aluminum feedstock comprises at least 25 wt. % aluminum. In another embodiment, an aluminum feedstock comprises at least 30 wt, % aluminum. In yet another embodiment, an aluminum feedstock comprises at least 35 wt. % aluminum. In another embodiment, an aluminum feedstock comprises at least 40 wt. % aluminum. In yet another embodiment, an aluminum feedstock comprises at least 45 wt. % aluminum. In another embodiment, an aluminum feedstock comprises at least 50 wt. % aluminum. In yet another embodiment, an aluminum feedstock comprises at least 55 wt. % aluminum. In another embodiment, an aluminum feedstock comprises at least 60 wt. % aluminum. In yet another embodiment, an aluminum feedstock comprises at least 65 wt. % aluminum. In anotherAttorney Ref. No.: 169593.120020 / WQembodiment, an aluminum feedstock comprises at least 70 wt. % aluminum. In yet another embodiment, an aluminum feedstock comprises at least 75 wt. % aluminum. In another embodiment, an aluminum feedstock comprises at least 80 wt. % aluminum. In one embodiment, an aluminum feedstock comprises not greater than 98 wt. % aluminum, in another embodiment, an aluminum feedstock comprises not greater than 95 wt. % aluminum. In yet another embodiment, an aluminum feedstock comprises not greater than 90 wt. % aluminum.

[0038] In one embodiment, the aluminum feedstock is substantially free of alumina (AI2O3) having not greater than 5 wt. % alumina therein. In another embodiment, the aluminum feedstock comprises not greater than 4 wt. % alumina. In yet another embodiment, the aluminum feedstock comprises not greater than 3 wt. % alumina. In another embodiment, the aluminum feedstock comprises not greater than 2 wt. % alumina. In yet another embodiment, the aluminum feedstock comprises not greater than 1 wt. % alumina. In another embodiment, the aluminum feedstock comprises not greater than 0.5 wt. % alumina. In yet another embodiment, the aluminum feedstock comprises not greater than 0.1 wt. % alumina.

[0039] In some embodiments, at least some of the purified aluminum metal (116) may be removed from the aluminum purification cell (100). In some embodiments, the purified aluminum metal (116) may be removed continuously, essentially continuously, or periodically during operation of the aluminum purification cell (100). In some embodiments, the removing step is completed with equipment configured to remove the purified aluminum metal (116) without contaminating the purified aluminum metal product (e.g., using alumina, graphite, and / or boride-based tapping equipment).

[0040] In some embodiments, an inert atmosphere may be introduced to the cell chamber (118) via, for example, a gas inlet. In this regard, the cell chamber (118) may be sealed from the ambient atmosphere by, for example, a top cover positioned over the upper portion of the cell chamber (118). Examples of inert gases include helium, argon, and nitrogen, among others.zzz. Metal Collector

[0041] Referring to FIG. 2, in one embodiment, the aluminum purification cell (100) includes a liquid metal collector (120). In one embodiment, the liquid metal collector (120) is located at an upper portion of the aluminum purification cell (100) and surrounds at least a portion of the at least one cathode (114). In some embodiments, the liquid metal collector ( 120) may have an inverted cup or funnel shape and may comprise a collector top (122) and at least one collector wall (124) at or near a periphery of the collector top (122). The liquid metalAttorney Ref. No.: 169593.120020 / WQcollector (120) may have any suitable shape and size. For example, the liquid metal collector (120) may comprise one or more collector walls (124) having planar, arcuate, and / or other suitably shaped exterior and / or interior surfaces. An inner surface (126) of the at least one collector wall (124) may extend vertically, as illustrated in FIG. 2, or may extend in a non¬ vertical direction, as discussed below. An inner surface (123) of tire collector top (122) may extend horizontally or in any other suitable direction and may have any suitable planar, arcuate, and / or other suitable surface shape. The inner surface (126) of the at least one collector wall (124) and the inner surface (123) of the collector top (122) may define a recessed collection region (128) for collecting purified aluminum metal (116) within the liquid metal collector (120). The inner surface (126) of the at least one collector wall (124) may face the collection region (128). A lower portion of the liquid metal collector (120) opposite the collector top (122) may define an opening (129) that is open to the electrolyte (110) to enable metallic aluminum in the electrolyte (110) to pass into the interior of the liquid metal collector (120) as the metallic aluminum moves upward under buoyant forces exerted on the metallic aluminum by the electrolyte (110), which has a higher density than the metallic aluminum. As shown in FIG. 2, the cathode (114) may pass from the collector top (122) through the interior of the liquid metal collector (120) and the opening (129).

[0042] As shown in FIG. 2, the cathode (114) may extend through the collection region (128) (e.g., through a central portion of the collection region (128)) such that metallic aluminum collected on the surface of the cathode (114) may move upward along the surface of the cathode (114) from a portion of the cathode (114) immersed in the electrolyte (110) to the collection region (128) via the opening (129). In some embodiments, at least a portion of metallic aluminum present in the electrolyte (110) may also move upward through the electrolyte (110) into the collection region (128) within the liquid metal collector (120) without first passing along a surface of the cathode (114). The metallic aluminum may be collected in the layer of purified aluminum metal (116) in the collection region (128). As shown in FIG. 2, the layer of purified aluminum metal (116) is disposed at an upper region of the liquid metal collector (120) above a zone of the electrolyte (110) located within the liquid metal collector (120).

[0043] The liquid metal collector (120) may be spaced apart from the cell sidewall (106) of the aluminum purification cell (100) such that collector walls (124) and / or other portions of the liquid metal collector (120) do not contact the cell sidewall (106). Additionally, the liquid metal collector (120) may restrict (e.g., prevent) the purified aluminum metal (116) from contacting the cell sidewall (106) of the aluminum purification cell (100) and / or fromAttorney Ref. No.: 169593.120020 / WOother regions of the aluminum purification cell (100) located outside the liquid metal collector (120). In some embodiments, the purified aluminum metal (116) accumulated within the collection region (128) within the liquid metal collector (120) may be held within the collection region (128) by the at least one collector wall (124) and / or the collector top (122). A substantial proportion of metallic aluminum produced within the electrolyte (110) may be collected within collection region (128) of the liquid metal collector (120), For example, metallic aluminum wetted on surfaces of the cathode (114) may move primarily along the cathode (114) surfaces into the collection region (128). Additionally, opening (129) of liquid metal collector (120) may be sufficiently wide to facilitate collection of a substantial proportion of metallic aluminum produced within the electrolyte (110). In some embodiments, inner surface(s) (126) of the at least one collector wall (124) may guide metallic aluminum toward the purified aluminum metal (116) within the collection region (128). In some embodiments, collecting the purified aluminum metal (116) within the collection region (128) of the liquid metal collector (120) may also facilitate extraction of the purified aluminum metal (116) from the aluminum purification cell (100) by collecting the purified aluminum metal (116) within the defined collection region (128), which is narrower than the cell chamber (118).

[0044] In one embodiment, a majority of purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120). In another embodiment, not less than 60% of the purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120). In yet another embodiment, not less than 70% of the purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120). In another embodiment, not less than 80% of the purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120). In another embodiment, not less than 90% of the purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120). In another embodiment, not less than 95% of the purified aluminum metal produced within the aluminum purification cell (100) is collected within the interior of the liquid metal collector (120).

[0045] The liquid metal collector (120) may thus restrict purified aluminum metal from accumulating in regions of the aluminum purification cell (100) outside the liquid metal collector (120). Accordingly, problems associated with accumulation of conductive metallic aluminum in regions of the aluminum purification cell (100) at or near the cell sidewall (106) may be prevented. For example, in some embodiments, the cell sidewall (106) may be a “hotAttorney Ref. No.: 169593.120020 / WOwall” that is electrically connected to the anodic current source. For example, the cell side wall (106) may comprise a conductive material (e.g., graphite) that is electrically connected to the anodic current source via the cell bottom (104) and / or the molten metal pad (108) contacting the cell sidewall (106). A layer of purified aluminum metal contacting both the negatively charged cathode (114) and the positively charged cell sidewall (106) may undesirably create a direct electrical path (i.e., a short) between the oppositely charged regions, reducing or eliminating the electrolytic functionality of the aluminum purification cell (100). Because the liquid metal collector (120) may assume a negative charge from contact with the cathode (114) and / or the purified aluminum metal (116), buildup of a layer of metallic aluminum outside the liquid metal collector (120) could also lead to electrical shorting between the liquid metal collector (120) and the cell sidewall (106) via a conductive metallic aluminum layer formed outside the liquid metal collector (120). Accordingly, by restricting the amount of metallic aluminum migrating to regions of the aluminum purification cell (100) outside the liquid metal collector (120), the collector (120) may preven t an electrical short due to formation of a direct electrical connection via a layer of metallic aluminum developed in a region between the cathode (114) and the cell sidewall (106) and / or between the liquid metal collector (120) and the cell sidewall (106). In some embodiments, metallic aluminum that migrates to regions of the aluminum purification cell (100) outside the liquid metal collector (120) may primarily accumulate in a zone on top of the electrolyte (110). Metallic aluminum disposed on the electrolyte (110) in regions outside the liquid metal collector (120) may be removed as needed from the aluminum purification cell (100) to prevent accumulation of the metallic aluminum in an amount sufficient to cause an electrical short between the cathodic and anodic regions of the aluminum purification cell (100).

[0046] In some embodiments, an amount of the electrolyte (110) within the liquid metal collector (120) may decrease as the amount of purified aluminum metal (116) accumulated within the liquid metal collector (120) increases and displaces the electrolyte (110). The at least one collector wall (124) may extend to a sufficient distance from the collector top (122) to allow for increasing thickness of the layer of purified aluminum metal (116) within the liquid metal collector (120) as metallic aluminum accumulates within the layer of purified aluminum metal (116) during operation. At least part of the purified aluminum metal (116) may be removed continuously, essentially continuously, or periodically so that the level of the purified aluminum metal (116) layer accumulated within the liquid metal collector (120) does not reach the opening (129) of the liquid metal collector (120). Accordingly, removal of the purified aluminum metal (116) may prevent the purified aluminum metal (116) within tire liquid metalAttorney Ref. No.: 169593.120020 / WOcollector (120) from spilling from the bottom opening (129) of the liquid metal collector (120) to regions of the aluminum purification cell (100) outside the liquid metal collector (120).

[0047] The liquid metal collector (120) may comprise any suitable material or combination of materials. In one embodiment, the liquid metal collector (120) may comprise an electrically conductive material, such as graphite, titanium diboride (Tifh), zirconium diboride (ZrB2), and / or hafnium diboride (HfB2). In one embodiment, the liquid metal collector (120) may comprise an insulator material, including at least one of an electrically insulative ceramic and / or cermet material, such as an oxide, a boride, a nitride, and / or a carbide. In one embodiment, the liquid metal collector (120) may include an insulator material that includes at least one of alumina and boron nitride. In one embodiment, the liquid metal collector (120) may comprise an alumina material, such as a fused cast alumina.

[0048] In one embodiment, and with reference now to FIG. 3, an aluminum purification cell (200) may include a liquid metal collector (220) having at least one collector wall (224) with a sloped inner surface (226). As shown in this embodiment, the inner surface (226) of the at least one collector wall (224) may slope from an opening (229) defined at a distal end of the at least one collector wall (224) toward the collection region (228). In one embodiment, the inner surface (226) of the at least one collector wall (224) may extend in a non-vertical direction between the opening (229) and a collector top (222) of the liquid metal collector (220). In some embodiments, the inner surface (226) of the at least one collector wall (224) may slope inward from the opening (229) toward the collection region (228), which is narrower than the opening (229) (i.e., a horizontal cross-sectional area of the collection region (228) may be smaller than the horizontal cross-sectional area of the opening (229)). Accordingly, metallic aluminum may be tunneled by the liquid metal collector (220) from a broader region of the electrolyte (110) toward the purified aluminum metal (116) in the narrower collection region (228). Collecting the purified aluminum metal (116) in the narrower collection region (228) may facilitate removal of the purified aluminum metal (116) by consolidating the purified aluminum metal (116) in a smaller zone within the liquid metal collector (220).

[0049] In one embodiment, and with reference now to FIG. 4, an aluminum purification cell (300) may include a liquid metal collector (320) having at least one collector wall (324) and at least one wettable element (330) disposed on a surface of the at least one collector wall (324). An outer surface (331) of the at least one collector wall (324) may face the cell sidewall (106) of the aluminum purification cell (100). As illustrated, the wettable element (330) may¬ be disposed on at least a portion of the outer surface (331) of the at least one collector wall (32.4) so that the wettable element (330) is exposed to the electrolyte (110), including regionsAttorney Ref. No.: 169593.120020 / WQof the electrolyte (110) outside the liquid metal collector (320). The wettable element (330) may comprise an aluminum-wettable surface that may be wetted with metallic aluminum within electrolyte (110). Accordingly, metallic aluminum within electrolyte (110) may selectively accumulate as an aluminum layer (332) on the wettable element (330) so as liquid metal collector to restrict the metallic aluminum from pooling on regions of the electrolyte (110) outside the liquid metal collector (320) (i.e., within regions of the aluminum purification cell (300) between the liquid metal collector (320) and the cell sidewall (106)). As such, the wettable element (330) may prevent electrical shorting between the liquid metal collector (120) and the cell sidewall (106) due to development of a conductive metallic aluminum layer.

[0050] The wettable element (330) may be any suitable shape and size and may be disposed on any suitable portion of the at least one collector wall (324) and / or other suitable portions of the liquid metal collector (320), such as a portion of a collector top (322) of liquid metal collector (320). In some embodiments, the wettable element (330) may comprise a wettable plate that is positioned along at least a portion of the outer surface (331) of the at least one collector wall (324). In one embodiment, multiple wettable elements (330) may be disposed at various positions on the at least one collector wall (324). The wettable element (330) may comprise any suitable aluminum wettable material, such as a material that is essentially the same as or different than a material of the collector wall (324). In one embodiment, the wettable element (330) may comprise a boride material, such as TiB2, ZrB2, and / or HfB2.

[0051] In one embodiment, and with reference now to FIG. 5, an aluminum purification cell (400) may include a liquid metal collector (420) having an extraction port (434) for extracting purified aluminum metal (416) from a collection region (428) surrounded by at least one collector wall (424). In the illustrated embodiment, the extraction port (434) may extend through a portion of the liquid metal collector (420), such as a collector top (422). The extraction port (434) may extend between the collection region (428) and an exterior of the aluminum purification cell (400), As shown, the collector top (422) may pass through a top cover (436) of the aluminum purification cell (400) so that the port is accessible from an exterior of the aluminum purification cell (400). The purified aluminum metal (416) may be continuously, essentially continuously, or periodically extracted from the collection region (428) via the extraction port (434), In some embodiments, the purified aluminum metal (416) may be extracted with equipment configured to remove the purified aluminum product without contaminating the product (e.g., using alumina, graphite, and / or boride-based tapping equipment). In some embodiments, the extraction port (434) may be sealed (e.g., by a portAttorney Ref. No.: 169593.120020 / WQcover) between periodic extractions. In one embodiment, purified aluminum metal (416) may migrate at least partially up a channel of the extraction port (434) under a buoyant force exerted on the purified aluminum metal (416) by the electrolyte (110) below the purified aluminum metal (416) so as to facilitate extraction of the purified aluminum metal (416).

[0052] In one embodiment, and with reference now to FIG. 6, an aluminum purification cell (500) may have a plurality of cathodes (514i)-(514m) that are at least partially surrounded by a liquid metal collector (520). The plurality of cathodes (514i)-(514m) may overlap a corresponding plurality of anodes (512j )-(512n) in an alternating manner. The aluminum purification cell (500) may include any suitable number (m) of cathodes (5141)-(514m) and any suitable number (n ) of anodes (512i)-(512n) in any suitable configuration. For example, a single aluminum purification cell (500) may include tens, hundreds, or thousands of anodes and cathodes. As shown, the cathodes (514i)-(514m) may be surrounded by at least one collector wall (524) such that the cathodes ( 14i)-(514m) all pass through a collection region (528) of the liquid metal collector (520), which includes a layer of purified aluminum metal (516) in the collection region (528).

[0053] In some embodiments, the aluminum purification cell (500) includes a cell bottom (504). In some embodiments, the upper surface of the cell bottom (504) is sloped. In some embodiments, the slope comprises an angle of less than 10 degrees. In some embodiments, the slope comprises an angle of about 3 to 5 degrees. In some embodiments, the aluminum purification cell (500) includes a cathode connector (544) proximal the liquid metal collector (520). The cathode connector (544) may be configured to connect to an external power source. At least a portion of the cathode connector (544) and / or one or more of the cathodes (5141)~(514m) may pass through a collector top (522) or other suitable portion of the liquid metal collector (520).

[0054] In some embodiments, the cell sidewalls (506), the cell bottom (504), and the top cover (536) of the aluminum purification cell (500) at least partially define a cell chamber (518) within the aluminum purification cell (500). The cell sidewalls (506), the top cover (536), and the cell bottom (504) may be made of a stable material (e.g., a refractory material) that is generally inert to the liquid / molten conditions of the aluminum purification cell (500). The cell chamber (518) may include a molten metal pad (508), an electrolyte (510) disposed on the molten metal pad (508), and a zone of purified aluminum metal (516) disposed above the electrolyte (510) within the liquid metal collector (520).

[0055] In some embodiments, the aluminum purification cell (500) may include a cell access channel (538) penetrating the cell chamber (518), thereby providing access to the lowerAttorney Ref. No.: 169593.120020 / WQportion of the cell chamber (518). The cell access channel (538) may have an access port (540). Aluminum feedstock (542) may be added to the aluminum purification cell (500) via the access port (540). The aluminum feedstock may include, for instance aluminum scrap, primary aluminum, and / or secondary aluminum. In some embodiments, the aluminum purification cell (500) may include an aluminum extraction port (not shown) penetrating the liquid metal collector (520) (see, e.g., FIG. 5), thereby providing access to purified aluminum metal (516) within the collection region (528) of the liquid metal collector (520). Purified aluminum metal (516) may be extracted from the aluminum purification cell (500) via the extraction port. In some embodiments, the aluminum purification cell (500) may also include an inert gas inlet (not shown) formed, for example, in the top cover (536) to provide an inert atmosphere to the cell chamber (518). Examples of inert gases include helium, argon, and nitrogen, among others. In some embodiments, a method includes purging the cell chamber (518) with an inert gas.

[0056] In some embodiments, the method may include adding aluminum feedstock (542) into the cell chamber (518) via the cell access port (540). In some embodiments, the aluminum feedstock (542) may be added continuously, essentially continuously, or periodically during operation of the aluminum purification cell (500). In some embodiments, the aluminum feedstock (542) may be added by metering the aluminum feedstock (542) at a first feed rate. In some embodiments, the aluminum feedstock (542) may be added periodically.

[0057] In some embodiments, sludge (546) may be produced as a by-product of the aluminum purification. As used herein, “sludge” means waste material precipitated during aluminum purification. In some embodiments, sludge (546) comprises highly viscous or solid material. The sludge (546) may have a higher density than the molten metal pad (508). As described above, an upper surface of the cell bottom (504) may be sloped. In some embodiments, the slope may run from a cell sidewall (506) down towards the cell access channel (538). Thus, the sludge (546) may drain along the upper surface of the cell bottom (504) towards the cell access channel (538). In some embodiments, the sludge may be removed from the cell chamber (518) via the cell access channel (538). In some embodiments, impurities may tend to collect in the molten metal pad (508). Thus, the cell access channel (538) may facilitate removal of at least a portion of the molten metal pad (508).zv, Miscellaneous

[0058] The present disclosure is explained with reference to the attached drawings, wherein like structures may be referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed uponAttorney Ref. No.: 169593.120020 / WOillustrating the principles of the present disclosure. Further, some features may be exaggerated to show details of particular components.

[0059] The figures constitute a part of this specification and include illustrative embodiments of the present disclosure and illustrate various objects and features thereof. In addition, any measurements, specifications and the like shown in the figures are intended to be illustrative, and not restrictive. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

[0060] Among those benefits and improvements that have been disclosed, other objects and advantages of this disclosure will become apparent from the following description taken in conjunction with the accompanying figures. Detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that tire disclosed embodiments are merely illustrative of the disclosure that may be embodied in various forms.

[0061] Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrases "‘in one embodiment” and “in some embodiments” as used herein do not necessarily refer to tire same embodiment(s), although they may. Furthermore, the phrases “in another embodiment,” “in yet another embodiment,” and “in some other embodiments” as used herein do not necessarily refer to a different embodiment, although they may. Thus, as described below, various embodiments of the disclosure may be readily combined, without departing from the scope or spirit of the disclosure.

[0062] In addition, as used herein, the term "or" is an inclusive "or" operator, and is equivalent to the term "and / or," unless the context clearly dictates otherwise. The term "based on" is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on.

[0063] While various embodiments of the present disclosure have been described in detail, it is apparent that modifications and adaptations of those embodiments -will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present disclosure.

Claims

Attorney Ref. No.: 169593.120020 / WQCLAIMSWhat is claimed is:

1. An aluminum purification cell, comprising:(a) an electrolyte disposed above a molten metal pad;(b) at least one cathode partially positioned within the electrolyte and a purified aluminum metal disposed on the electrolyte; and(c) a liquid metal collector surrounding at least a portion of the at least one cathode configured to collect, within a collection region comprising the purified aluminum metal, metallic aluminum produced at a surface of the at least one cathode.

2. Tlie aluminum purification cell of claim 1, wherein the liquid metal collector restricts the metallic aluminum from contacting a side wall of the aluminum purification cell.

3. The aluminum purification cell of claim 1 or 2, wherein the liquid metal collector comprises a collector wall at least partially surrounding a portion of the electrolyte and the collection region disposed above the portion of the electrolyte.

4. Tire aluminum purification cell of claim 3, wherein the collector wall is configured to guide the metallic aluminum to the collection region.

5. The aluminum purification cell of claim 3 or 4, wherein the collector wall is configured to at least partially separate the collected metallic aluminum from a region of the aluminum purification cell surrounding the collector wall.

6. Tire aluminum purification cell of any of claims 3-5, wherein the collector wall is spaced apart from a sidewall of the aluminum purification cell.

7. The aluminum purification cell of any of claims 3-6, wherein the liquid metal collector comprises a collector top disposed above the collection region.

8. The aluminum purification cell of claim 7, wherein the collector wall extends downward from the collector top.Attorney Ref. No.: 169593.120020 / WQ9. The aluminum purification cell of claim 7 or 8, wherein the at least one cathode passes at least partially through the collector top.

10. The aluminum purification cell of claim 9, wherein the at least one cathode is electrically coupled to a power source at location above the collection region.

11. The aluminum purification cell of any of claims 7-10. wherein the at least one cathode extends from the collector top through the collection region into the electrolyte.

12. Tire aluminum purification cell of any of claims 7-11, wherein an inner surface of the collector top faces the collection region.

13. The aluminum purification cell of any of claims 7-12, wherein an inner surface of the collector top extends horizontally.

14. Hie aluminum purification cell of any of claims 7-13, wherein the collector top defines an extraction port for accessing the collection region from an exterior of the aluminum purification cell.

15. The aluminum purification cell of any of claims 3-14, wherein an inner surface of the collector wall faces the collection region and an outer surface of the collec tor wall faces a sidewall of the aluminum purification cell.

16. Tire aluminum purification cell of claim 15, wherein the inner surface of the collector wall slopes toward the collection region.

17. The aluminum purification cell of claim 15 or 16, wherein the inner surface of the collector wall slopes in a non-vertical direction.

18. Hie aluminum purification cell of claim 15, wherein the inner surface of the collector wall extends vertically.

19. The aluminum purification cell of any of claims 3-18, wherein:a first portion of the collector wall is disposed within the electrolyte; andAttorney Ref. No.: 169593.120020 / WQa second portion of the collector wall is disposed above the electrolyte.

20. Tire aluminum purification cell of any of claims 3-19, comprising a wettable element disposed on at least a portion of an outer surface of the collector wall, wherein the wettable element comprises an aluminum-wettable surface.

21. The aluminum purification cell of claim 20, wherein the wettable element comprises a different material than the collector wall.

22. Tire aluminum purification cell of claim 20 or 21, wherein the wettable element comprises a boride material.

23. The aluminum purification cell of claim 22, wherein the boride material comprises at least one of TiB2, ZrB2, and HfB2.

24. The aluminum purification cell of any of claims 20-23, wherein the wettable element comprises a wettable plate attached to the outer surface of the collector wall.

25. The aluminum purification cell of any of the preceding claims, comprising a cell cover, wherein the liquid metal collector passes through at least a portion of the cell cover,26. The aluminum purification cell of any of the preceding claims, wherein a portion of at least one of the at least one cathode and a connector electrically coupling the at least one cathode to a power source passes through a portion of the liquid metal collector,27. The aluminum purification cell of any of the preceding claims, wherein the at least one cathode extends through an upper surface of the of the liquid metal collector.

28. The aluminum purification cell of any of the preceding claims, wherein the liquid metal collector comprises an electrically conductive material.

29. Tire aluminum purification cell of claim 28, wherein the electrically conductive material comprises a carbonaceous material.Attorney Ref. No.: 169593.120020 / WQ30. The aluminum purification cell of claim 28 or 29, wherein the electrically conductive material comprises at least one of graphite, TiB2, ZrB2, and HfB2.

31. The aluminum purification cell of any of the preceding claims, wherein the liquid metal collector comprises an insulator material.

32. The aluminum purification cell of claim 31, wherein the insulator material comprises at least one of a cermet and a ceramic.

33. Tire aluminum purification cell of claim 31, wherein the insulator material comprises at least one of alumina and boron nitride.

34. The aluminum purification cell of claim 33, wherein the alumina comprises fused cast alumina.

35. The aluminum purification cell of any of the preceding claims, wherein the at least one cathode comprises a solid material.

36. The aluminum purification cell of any of the preceding claims, wherein the at least one cathode composes a non -carbonaceous material.

37. The aluminum purification cell of claim 36, wherein the non-carbonaceous material comprises at least one of TiB2, ZrB2, and HfB2.

38. Tire aluminum purification cell of any of the preceding claims, wherein the at least one cathode is electrically coupled to a cathodic current source.

39. The aluminum purification cell of claim 38, wherein the at least one cathode comprises a plurality of cathodes electrically coupled to the cathodic current source via a cathode connector.

40. Tire aluminum purification cell of any of the preceding claims, wherein the electrolyte comprises a density greater than the purified aluminum metal.Attorney Ref. No.: 169593.120020 / WQ41. The aluminum purification cell of any of the preceding claims, wherein the electrolyte comprises at least one of fluoride salts and chloride salts.

42. The aluminum purification cell of claim 41, wherein a cation of the fluoride salts or the chloride salts is one or more of Li, Na, K, Al, Ba, Ca, Mg, Ce, La, Cs, Rb, and combinations thereof,43. The aluminum purification cell of any of the preceding claims, wherein the electrolyte comprises both (a) at least one of BaFT and LaFs, and (b) at least one of AlFs, KF, MgF2, and NaF.

44. lire aluminum purification cell of any of the preceding claims, wherein a temperature of the electrolyte is from 700 to 980 degrees Celsius,45. The aluminum purification cell of any of the preceding claims, wherein the molten metal pad comprises at least one of Al, Si, Cu, Fe, Sb, Gd, Cd, Sn, Pb, Mg, Zn, Ti, and B.

46. The aluminum purification cell of any of the preceding claims, wherein the molten metal pad comprises aluminum.

47. The aluminum purification cell of any of the preceding claims, wherein the molten metal pad comprises at least 20 wt. % Al.

48. A method, comprising:(a) producing aluminum ions from an aluminum-based feedstock, wherein the aluminum ions are produced in an electrolyte disposed above a molten metal pad in an aluminum purification cell;(b) forming metallic aluminum by reducing the aluminum ions on at least one cathode partially positioned in the electrolyte; and(c) collecting the metallic aluminum in a purified aluminum metal disposed within a collection region located above the electrolyte, wherein the purified aluminum metal in the collection region is restricted from a sidewall of tire aluminum purification cell by a liquid metal collector surrounding the purified aluminum metal.Attorney Ref. No.: 169593.120020 / WQ49. The method of claim 48, wherein the collecting step (c) comprises conveying at least a portion of the metallic aluminum along a surface of the liquid metal collector toward the collection region.

50. The method of claim 49, wherein the surface of the liquid metal collector comprises an inner surface of a collector wall of the liquid metal collector.

51. The method of claim 49 or 50, wherein the surface of the liquid metal collector is disposed at least partially in the electrolyte.

52. The method of any of claims 49-51, wherein the conveying step comprises conveying at least the portion of tire metallic aluminum along a portion of the surface of the liquid metal collector that slopes toward the collection region.

53. The method of any of claims 48-52, comprising restricting, by the liquid metal collector, migration of the metallic aluminum from the electrolyte to a region surrounding an outer surface of the liquid metal collector.

54. The method of any of claims 48-53, comprising wetting a surface of a wettable element with metallic aluminum, wherein the wettable element is located on a peripheral portion of the liquid metal collector between the collection region and the sidewall of the aluminum purification cell.

55. The method of any of claims 48-54, wherein the collecting step (c) comprises conveying at least a portion of the metallic aluminum along a surface of a liquid metal collector, wherein the surface is disposed at least partially in the electrolyte.

56. The method of claim 55, wherein the conveying step comprises conveying at least the portion of the metallic aluminum along a vertical portion of the surface of the liquid metal collector.

57. The method of claim 55 or 56, wherein the conveying step comprises conveying at least the portion of the metallic aluminum along a sloped portion of the surface of the liquid metal collector.Attorney Ref. No.: 169593.120020 / WQ58. The method of any of claims 55-57, wherein the surface of the liquid metal collector surrounds at least a portion of the at least one cathode.

59. Hie method of any of claims 55-58, wherein the surface of the liquid metal collector comprises an inner surface of a collector wall of the liquid metal collector.

60. Tlie method of claim 59, wherein a portion of the inner surface of the collector wall surrounding the electrolyte is wider than an inner surface of the collector wall surrounding the collection region.

61. The method of any of claims 48-60, comprising removing at least a portion of the purified aluminum metal from the collection region.

62. The method of claim 61, wherein the removing step comprises extracting at least the portion of the purified aluminum metal from the collection region to a location outside aluminum purification cell.

63. Hie method of any of claims 48-62, comprising adding additional aluminum-based feedstock to a region of the aluminum purification cell near the molten metal pad.

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