Systems and methods for refining aluminum

Abstract

The present application is directed to a system and method for aluminum refining, the system comprising a cell defining a chamber having an upper portion and a lower portion, the lower portion including a cathode melt collection area, an anode structure disposed within the upper portion vertically aligned above the lower portion, a cathode structure disposed within the upper portion vertically aligned above the cathode melt collection area, and a liquid electrolyte in the chamber in fluid communication with the anode structure and the cathode structure, the liquid electrolyte having an electrolyte density, the anode structure configured to receive impure aluminum having an impure aluminum density greater than the electrolyte density, and the cathode structure captures refined aluminum having a refined aluminum density greater than the electrolyte density, the cathode structure defining a cathode flow path through which the refined aluminum can flow.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Application No. 63 / 318,595, filed March 10, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Commercially available aluminum electrorefining cells can be based on three-layer Hoopes cells and can be used to produce high purity aluminum. A Hoopes cell is a horizontal electrorefining cell consisting of a molten electrolyte separating two molten electrodes: impure aluminum alloyed with copper as the anode, and pure aluminum acting as the cathode. The impure aluminum is alloyed with copper to make it denser, which causes the impure aluminum and copper alloy to form the anode layer at the bottom of the cell. Additionally, the Hoopes cell configuration requires an electrolyte with a density greater than that of pure aluminum so that the pure aluminum can form the top cathode layer floating in the electrolyte in the three-layer cell. During electrolysis, aluminum ions migrate from the electrolyte layer to the top cathode layer, replacing aluminum ions produced in the bottom anode layer and migrating to the electrolyte layer. Although the theoretical energy cost associated with operating a Hoopes cell is minimal, the actual operating energy cost is significant due primarily to the resistivity of the cell, which is a function of the distance between the electrodes and the conductivity of the electrolyte. It is difficult to reduce the distance between the electrodes of a HOOPS cell and / or to increase the conductivity of the electrolyte. For example, only electrolytes with the required density characteristics can be used, and dense electrolytes tend to have low conductivity. Furthermore, in HOOPS cell-based electrorefining processes, the aluminum in the anode layer at the bottom of the cell can become depleted over time, which can lead to HOOPS cell-based systems requiring periodic replacement of the aluminum-depleted anode layer with new impure aluminum and copper alloy material, reducing the efficiency of the system. Thus, there is a need in the art for electrorefining systems and methods for aluminum purification that are less energy intensive than systems and methods associated with HOOPS cells. There is also a need for electrorefining systems that are capable of continuous operation.

[0003] [Means for solving the problem]

[0013] The objects and advantages of the disclosed subject matter will be set forth in and become apparent from the following description, as well as learned by practice of the disclosed subject matter. By way of illustration and not limitation, the various embodiments described herein relate to systems and methods for refining aluminum. Additional advantages of the disclosed subject matter will be realized and attained by the systems and methods particularly pointed out in the written description and claims hereof, as well as the appended drawings.

[0004] To achieve these and other advantages, and in accordance with the objects of the disclosed subject matter as embodied and broadly described, the disclosed subject matter includes a system and method for aluminum refining. An aluminum refining system in accordance with the disclosed subject matter includes a cell defining a chamber having an upper portion and a lower portion. The lower portion includes a cathode melt collection area defined therein. The system in accordance with the disclosed subject matter further includes an anode structure disposed in the upper portion of the chamber and vertically disposed above the lower portion, and a cathode structure disposed in the upper portion of the chamber and vertically disposed above the cathode melt collection area. A liquid electrolyte is contained within the chamber in fluid communication with the anode structure and the cathode structure. The anode structure is configured to receive the impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density. Additionally, the cathode structure is configured to capture the refined aluminum in a molten state, the refined aluminum having a refined aluminum density greater than the electrolyte density, from the impure aluminum via the liquid electrolyte, the cathode structure further defining a cathode flow path through which the refined aluminum can flow from a top portion to the cathode melt collection area.

[0005] An interface may be defined between the liquid electrolyte and the molten aluminum contained in the cathode melt collection area, the interface may be below the cathode structure, and the liquid electrolyte may be free to flow between the anode structure and the cathode structure.

[0006] According to one aspect of the disclosed subject matter, the anode structure can include a first anode structure portion and a second anode structure portion with an anode reservoir therebetween, and the anode structure can be configured to receive the impure aluminum in the anode reservoir. For example, a first side of the second anode structure portion can be in fluid communication with the impure aluminum, and a second side of the second anode structure portion can be in fluid communication with the liquid electrolyte. The second anode structure portion can include pores. For example, the pores of the second anode structure portion can be sized to prevent the impure aluminum from passing through the pores and to allow aluminum ions to pass through the pores. Additionally or alternatively, the second anode structure portion can be configured to be impregnated with impure aluminum. Additionally or alternatively, the second anode structure portion can be configured to allow the impure aluminum to pass slowly through the anode surface.

[0007] The lower portion may include an anode melt collecting area. The anode structure may be vertically aligned above the anode melt collecting area. Additionally or alternatively, a cathode melt collecting area may be separated from the anode melt collecting area by a partition disposed therebetween. An interface may be defined between the liquid electrolyte and the molten aluminum contained in each of the anode melt collecting area and the cathode melt collecting area, and the partition may extend into the chamber from the bottom of the cell to a height above the interface. Additionally or alternatively, the liquid electrolyte may have a top surface, and the partition may not contact the top surface of the liquid electrolyte.

[0008] According to one aspect of the disclosed subject matter, the anode structure can define an anode flow path through which the impure aluminum in a molten state can flow from the top portion to the anode melt collection area. For example, the anode flow path can extend from the anode reservoir through the second anode structure portion to the anode melt collection area.

[0009] Additionally or alternatively, the anode structure may include an aluminum-wettable material. The anode flow channel may include a layer of impure aluminum molten along a surface of the anode structure. The aluminum-wettable material may include titanium diboride (TiB 2 ) can be included. For example, TiB 2 may be an electroplated layer on a surface of the anode structure. Additionally or alternatively, the anode structure may include graphite, TiB 2 A layer can be disposed thereon.

[0010] According to another aspect of the disclosed subject matter, the cathode structure may include the aluminum-wettable material. Additionally or alternatively, the cathode flow channel may include a layer of molten refined aluminum along a surface of the cathode structure. The aluminum-wettable material may include TiB 2 For example, TiB 2 may be an electroplated layer on the surface of the cathode structure. Additionally or alternatively, the cathode structure may include graphite, TiB 2 A layer can be disposed thereon. Additionally or alternatively, the cathode structure can include tungsten.

[0011] In accordance with another aspect of the disclosed subject matter, the anode structure and the cathode structure can both include an aluminum wettable material, for example, the anode structure and the cathode structure can both include the same wettable material.

[0012] According to another aspect of the disclosed subject matter, the liquid electrolyte is a mixture of lithium fluoride (LiF) and aluminum fluoride (AlF 3 The liquid electrolyte may include sodium fluoride (NaF), potassium fluoride (KF), calcium fluoride (CaF 2 ), and other metal fluorides that are in balance with the purification process. The liquid electrolyte may contain about 2.7 g / cm 3 The density may be less than 100 nm.

[0013] According to one aspect of the disclosed subject matter, the distance between the anode structure and the cathode structure can be about 2 mm to about 5 cm.

[0014] The disclosed subject matter further includes a method of aluminum refining. The method according to the disclosed subject matter includes the step of operating an aluminum refining system having any of the features described above. The method according to the disclosed subject matter further includes the step of introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into a chamber for receipt by an anode structure. As embodied herein, the anode structure can define an anode flow path through which the impure aluminum can flow from the top to an anode melt collection area. The method according to the disclosed subject matter further includes the step of capturing refined aluminum in a molten state having a refined aluminum density greater than the electrolyte density in a cathode structure through a liquid electrolyte from the impure aluminum, the cathode structure defines a cathode flow path through which the refined aluminum can flow from the top to a cathode melt collection area, and collecting the refined aluminum discharged from the cathode structure in a second melt collection area.

[0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the disclosed subject matter as claimed.

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to illustrate and provide a further understanding of the systems and methods of the disclosed subject matter and, together with the specification, serve to explain the principles of the disclosed subject matter. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional side view of an aluminum refining system in accordance with the disclosed subject matter; [Diagram 2] 1 is an exemplary method of aluminum refining in accordance with the disclosed subject matter. [Diagram 3] 1 is a schematic cross-sectional side view of an aluminum refining system in accordance with the disclosed subject matter. [Figure 3A] 1 is a schematic cross-sectional side view of an aluminum refining system in accordance with the disclosed subject matter. [Figure 4] 1 is a schematic partial cross-sectional side view of an aluminum refining system in accordance with the disclosed subject matter; [Diagram 5] 1 is a schematic partial cross-sectional side view of an aluminum refining system in accordance with the disclosed subject matter; Summary of the Invention [Problem to be solved by the invention]

[0018] Reference will now be made in detail to various exemplary embodiments of the disclosed subject matter, which are illustrated in the accompanying drawings. The structure and corresponding method of operation of the disclosed subject matter will be described in conjunction with a detailed system description. The accompanying drawings, in which like reference numerals refer to identical or functionally similar elements throughout the separate views, serve to further explain various embodiments in accordance with the disclosed subject matter, and to explain various principles and advantages thereof, all of which are incorporated herein by reference.

[0019] The disclosed subject matter is generally directed to systems and methods for aluminum refining. An aluminum refining system according to the disclosed subject matter generally includes a cell defining a chamber. The chamber includes an upper portion and a lower portion. The lower portion includes a cathode melt collection area defined therein.

[0020] The system according to the disclosed inventive subject matter further includes an anode structure and a cathode structure disposed in an upper portion of the chamber. The anode structure is vertically aligned above the lower portion. The cathode structure is vertically aligned above the cathode melt collection area. The system according to the disclosed inventive subject matter further includes a liquid electrolyte within the chamber and in fluid communication with the anode structure and the cathode structure. The liquid electrolyte has an electrolyte density.

[0021] In accordance with the disclosed subject matter, the anode structure is configured to receive impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density. The cathode structure is configured to capture refined aluminum in a molten state from the impure aluminum via the liquid electrolyte, the refined aluminum having a refined aluminum density greater than the electrolyte density. The cathode structure further defines a cathode flow passage through which the refined aluminum can flow from the top to a cathode melt collection area.

[0022] The disclosed subject matter further includes a method of refining aluminum. The method of refining aluminum according to the disclosed subject matter generally includes operating a refining system. The system includes a cell defining a chamber. The chamber includes an upper portion and a lower portion. The lower portion includes a cathode melt collection area defined therein. The system further includes an anode structure and a cathode structure disposed in an upper portion of the chamber. The anode structure is vertically aligned above the lower portion. The cathode structure is vertically aligned above the cathode melt collection area. A liquid electrolyte is within the chamber and in fluid communication with the anode structure and the cathode structure.

[0023] The method of aluminum refining in accordance with the disclosed inventive subject matter further includes introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into the chamber for receipt by the anode structure. The method in accordance with the disclosed inventive subject matter further includes capturing refined aluminum in a molten state having a refined aluminum density greater than the electrolyte density from the impure aluminum via the liquid electrolyte in a cathode structure, the cathode structure defining a cathode flow passage through which the refined aluminum can flow from the top to a cathode melt collection area, and collecting refined aluminum discharged from the cathode structure in the cathode melt collection area.

[0024] For purposes of explanation and illustration, but not limitation, an exemplary system and method for aluminum refining according to the disclosed subject matter is illustrated in FIG. 1 and FIG. 2. 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 based on additional factors not listed unless the context clearly dictates otherwise. Additionally, throughout this specification, the meanings of "a," "an," and "the" include plural references. The meaning of "in" includes "in" and "on." As used herein, the term "purified aluminum" is a broad and relative term and includes materials having a higher wt.% aluminum than the impure aluminum materials.

[0025] For purposes of explanation and not limitation, reference is made to an exemplary aluminum refining system 100 in FIG. 1. In accordance with the disclosed subject matter, the refining system 100 comprises a cell 101 defining a chamber 102. The chamber 102 has an upper portion 103 and a lower portion 104. The lower portion 104 includes a cathode melt collection region 106. As embodied herein, the lower portion 104 may further include an anode melt collection region 105. Additionally or alternatively, the anode melt collection region 105 may be separated from the cathode molten material collection region 106 by a divider 107 disposed therebetween. As embodied herein, the anode melt collection region 105 and the cathode molten material collection region 106 may define respective reservoirs separated by the divider 107, each configured to receive molten material. As further embodied herein, the divider 107 can extend along a centerline of the system 100, and the anode melt collection area 105 and the cathode molten material collection area 106 can define respective reservoirs having approximately the same volume. Alternatively, the anode melt collection area 105 and the cathode molten material collection area can have different dimensions and volumes.

[0026] In accordance with the disclosed subject matter, the anode structure 108 is disposed in the upper portion of the chamber such that it is vertically aligned above the lower portion 104. As embodied herein, the anode structure 108 can be vertically aligned above the anode melt collection area 105. The anode structure 108 is configured to receive impure aluminum in a molten state having an impure aluminum density greater than an electrolyte density. By way of example, as embodied herein, the anode structure 108 can define an anode flow path through which the impure aluminum can flow from the top portion 103 to the anode melt collection area 105, as further described herein. As embodied herein, the anode structure 108 can include an aluminum-wettable material. Suitable aluminum-wettable materials for the anode structure can include, for example, materials having a contact angle with molten aluminum of 90° or less measured in the presence of a fluoride electrolyte, although aluminum-wettable materials having a contact angle of greater than 90° can also be used. By way of example, as embodied herein, the aluminum-wettable material can be titanium diboride (TiB 2 ). The anode structure may be comprised solely of the aluminum-wettable material. Alternatively, a layer of the aluminum-wettable material may be provided on the surface of the anode structure. For example, as embodied herein, the anode structure may include a graphite body and titanium diboride may be electroplated onto the graphite to form a layer of titanium diboride on the surface of the anode structure. Additionally or alternatively, titanium diboride may be thermally sprayed onto the anode structure.

[0027] As embodied herein, the system 100 includes one anode structure 108, but may include additional anode structures. The number of anode structures may be selected based on the desired performance characteristics of the purification system. The anode structures may be used in parallel or in series. For example, molten aluminum may be collected in the cathode melt collection area 106 of the system 100 and transferred to an anode structure of another cell for further purification, as described further herein. Additionally or alternatively, impure aluminum may be collected in the anode melt collection area 105 and transferred to an anode structure of another cell for further purification. The molten aluminum may be processed through any desired number of cells in series, as described further herein, until the molten aluminum reaches a desired purity level. Additionally or alternatively, multiple anode structures may be included in a single cell.

[0028] According to the disclosed subject matter, the cathode structure 109 is disposed at the top of the chamber and vertically aligned above the cathode melt collection area 106. The cathode structure 109 defines a cathode flow path through which the refined aluminum can flow from the top to the cathode melt collection area 106, as described further herein. As embodied herein, the system 100 includes one cathode structure 109, but may include additional cathode structures. The number of cathode structures may be selected based on the desired performance characteristics of the purification system. For example, the cathode structures may be arranged in series or parallel, as described above. As embodied further herein, the cathode structure 109 may be disposed at the top 103 of the chamber opposite the anode structure 108, and may be spaced apart from the anode structure by an anode structure-cathode structure distance. The anode structure-cathode structure distance may be selected depending on the desired characteristics of the system. By way of example, the anode structure-cathode structure distance may be between 2 mm and 5 cm. As embodied herein, the anode structure-cathode structure distance may be about 4 cm.

[0029] As embodied herein, the cathode structure may include an aluminum-wettable material. Suitable aluminum-wettable materials for the cathode structure may include, for example, materials having a contact angle with molten aluminum of 90° or less, although aluminum-wettable materials having a contact angle of greater than 90° may also be used. As embodied herein, both the anode structure and the cathode structure may include an aluminum-wettable material. By way of example, an aluminum-wettable material for both the anode structure and the cathode structure may be titanium diboride (TiB 2 ). Additionally or alternatively, the anode structure and the cathode structure can have different aluminum-wettable materials. As discussed above, the cathode structure can be made entirely of the aluminum-wettable material. Alternatively, a layer of the aluminum-wettable material can be provided on the surface of the cathode structure. As embodied herein, the cathode structure can include a graphite body, and titanium diboride can be electroplated onto the graphite to form a layer of titanium diboride on the surface of the cathode structure.

[0030] Both the anode structure 108 and the cathode structure 109 are in fluid communication with a liquid electrolyte 110 in the chamber 102. As embodied herein, the liquid electrolyte may be disposed in the chamber 102 between the anode structure 108 and the cathode structure 109 and above the anode melt collection area 105 and the cathode melt collection area 106. As embodied herein, the electrolyte 110 may freely flow between the anode structure 108 and the cathode structure 109. The liquid electrolyte 110 has an electrolyte density. As described further herein, the impure aluminum added to the system 100 has an impure aluminum density greater than the electrolyte density. Additionally, the refined aluminum captured in the cathode structure has a refined aluminum density greater than the electrolyte density. As embodied herein, the liquid electrolyte has a top surface 111 at the top of the chamber, and the divider 107 is configured not to contact the top surface. As further embodied herein, an interface 117 can be defined between the liquid electrolyte 110 and the molten aluminum contained in the cathode melt collection region 106. The interface 117 can be below the cathode structure 109.

[0031] The liquid electrolyte can be any suitable medium in which the flow of electrical current is by the movement of ions / ionic species. By way of example and not limitation, the liquid electrolyte can include lithium fluoride, aluminum fluoride, and / or sodium fluoride. As embodied herein, the liquid electrolyte 110 can include lithium fluoride, aluminum fluoride, sodium fluoride, potassium fluoride, calcium fluoride, and other base metal fluorides, or combinations thereof that are balanced with the purification process. By way of example and not limitation, the liquid electrolyte can include sodium fluoride (NaF) and aluminum fluoride (AlF3). Additionally or alternatively, by way of example and not limitation, the liquid electrolyte can include lithium fluoride (LiF) and potassium fluoride (KF). As further described herein, the liquid electrolyte 110 can be selected to provide a desired electrolyte density and associated performance characteristics. For example, the liquid electrolyte can be about 2.7 g / cm3 The density may be less than 100 nm.

[0032] As embodied herein, the anode structure 108 can define an anode flow path through which impure aluminum 112 in a molten state, having an impure aluminum density greater than the electrolyte density, can flow from the top 103 to the anode melt collection area 105. The impure aluminum 112 can be heated to a molten state using any suitable means. By way of example and not limitation, the impure aluminum can be heated using waste heat from another manufacturing process, or the like.

[0033] As embodied herein, the anode structure 108 can include a wettable material as described above, and the anode flow path can include a thin layer of impure aluminum molten along the surface of the anode structure 108. For illustrative purposes, as embodied herein, the impure aluminum 112 can be introduced into the chamber 102 at the top of the anode structure 108, and the impure aluminum 112 can flow down the surface of the anode structure 108 opposite the cathode structure 109. As embodied herein, a thin film of impure aluminum 112 can be formed along the surface of the anode structure 108 as the impure aluminum flows from top to bottom along the surface of the anode structure 108. The anode structure 108 can be constructed of a non-conductive material, and the impure aluminum 112 can form a conductive anode of the system. The system 100 can further include one or more leads electrically connected to the conductive anode, as known in the art.

[0034] As embodied herein, the impure aluminum 112 can drip into the anode melt collection area 105 when the impure aluminum 112 reaches the lower end of the anode structure 108. Additionally or alternatively, the anode flow path can extend through the anode structure 108 or a portion thereof, as further described herein. The flow of the impure aluminum 112 from the top 103 to the anode melt collection area 105 is related, among other things, to the relative densities of the liquid electrolyte 110 and the impure aluminum 112. The impure aluminum 112 has a density greater than the electrolyte density and tends to flow down through the cell 101 and the liquid electrolyte 110. As further described herein, the system according to the disclosed subject matter can be used to purify said impure aluminum that is not alloyed with copper to increase its density, as is common in other aluminum refining systems such as HOOPS cells.

[0035] As mentioned above, the anode melt collecting area 105 can include an outlet 114 in fluid communication with the anode melt collecting area 105 for removing the impure aluminum 112 from the anode melt collecting area 105. As embodied herein, the impure aluminum 112 from the anode melt collecting area 105 can be recycled to the top of the system 100 and to the anode 108, for example, to maintain a thin film of impure aluminum 112 on the anode 108. For example, as embodied herein, the system 100 can include a pump 116 in fluid communication with the outlet 114, which can circulate the impure aluminum 112 from the anode melt collecting area 105 to the anode structure 108. Additionally or alternatively, the outlet 114 can be used to evacuate the impure aluminum 112 from the cell 101 and introduce new impure aluminum material into the cell. Additionally or alternatively, the impure aluminum 112 can be diverted through an outlet 114 to another cell.

[0036] In accordance with the disclosed subject matter, the cathode structure 109 is configured to capture molten refined aluminum 113 from the impure aluminum 112 via the liquid electrolyte 110, the refined aluminum having a density of the impure aluminum greater than the electrolyte density. The cathode structure 109 further defines a cathode flow path through which the refined aluminum 113 can flow from the top 103 to the cathode melt collection area 106. As discussed above with respect to the anode flow path, the flow of the refined aluminum 113 from the top 103 to the cathode melt collection area 106 is related to, among other things, the relative densities of the liquid electrolyte 110 and the refined aluminum 113. The refined aluminum 113 has a density greater than the electrolyte density and tends to flow down through the cell 101 and the liquid electrolyte 110. As further described herein, the system according to the disclosed subject matter can refine aluminum with greater efficiency than other systems, such as HOOPS cells, which require a liquid electrolyte having a density greater than that of the refined aluminum. For example, the system according to the disclosed subject matter can be used with electrolytes having higher electrical conductivity and lower density.

[0037] As embodied herein, the cathode structure 109 can include a wettable material as described above, and the cathode flow channels can include a thin layer of molten refined aluminum 113 along the surface of the cathode structure 109. As embodied herein, the refined aluminum 113 collected on the cathode structure 109 can flow along the vertically oriented cathode structure 109 and drip into the cathode melt collection area 106.

[0038] The cathode structure 109 can be constructed of a non-conductive material, and the refined aluminum 113 can form the conductive cathode of the system 100. The system 100 can further include one or more leads electrically connected to the conductive cathode, as known in the art. As embodied herein, a voltage and / or current can be applied across the anode and cathode, and aluminum ions from the thin film of aluminum on the surface of the anode structure 108 can migrate through the liquid electrolyte 110 to the cathode structure. As embodied herein, the aluminum ions can form a thin film of refined aluminum 113 on the surface of the cathode structure 109.

[0039] The cathode structure 109 may be configured to capture refined aluminum having a higher weight percent (wt.%) of aluminum than the impure aluminum introduced to the anode structure. By way of example and not limitation, impure aluminum having at least 80 wt.% aluminum may be introduced to the anode structure, and the refined aluminum captured in the cathode structure may have at least 99 wt.% aluminum. Additionally or alternatively, the refined aluminum captured in the cathode structure may have at least 99.5 wt.% aluminum. Additionally or alternatively, the refined aluminum captured in the cathode structure may have at least 99.9 wt.% aluminum.

[0040] The system 100 can include an outlet 115 in fluid communication with the cathode melt collection region 106. For example, as embodied herein, the outlet 115 can be in fluid communication with the cathode melt collection region 106 for removing refined aluminum 113 therefrom.

[0041] 3 illustrates another purification system 300 in accordance with the disclosed subject matter. In accordance with the disclosed subject matter, purification system 300 includes a cell 301 defining a chamber 302. Chamber 302 has an upper portion 303 and a lower portion 304. The lower portion includes a cathode melt collection area 306. As embodied herein, lower portion 304 can further include an anode melt collection area 305. Anode melt collection area 305 can be separated from cathode melt collection area 306 by a divider 307 disposed therebetween.

[0042] The system further includes an anode structure 308 disposed at the top of the chamber 302 and vertically aligned above the bottom portion 304. As embodied herein, the anode structure may be vertically aligned above the anode melt collection area 305. A cathode structure 309 is disposed at the top of the chamber 302 and vertically aligned above the cathode melt collection area 306. A liquid electrolyte 310 is disposed within the chamber 302 in fluid communication with the anode structure 308 and the cathode structure 309.

[0043] The anode structure 308 is configured to receive impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density. As embodied herein, the anode structure 308 can include a first anode structure portion 321 and a second anode structure portion 322 and an anode reservoir 323 therebetween. The anode structure 308 can receive impure aluminum 312 in the anode reservoir 323. As further embodied herein, a first side of the second anode structure portion 322 can be in fluid communication with the impure aluminum 312 and a second side of the second anode structure portion 322 can be in fluid communication with the liquid electrolyte 310. As embodied herein, the anode structure 308 can define an anode flow path through which the impure aluminum in a molten state 312 having an impure aluminum density greater than the electrolyte density can flow from the top portion 303 to the anode melt collection region 305. As embodied herein, the anode flow path can extend from the anode reservoir 323 through the second anode structure portion 322 to the anode melt collection area 305. For example, as further described herein, the second anode structure portion 322 can be porous and the impure aluminum 312 can flow from the anode reservoir 323 through the pores of the second anode structure portion 322 and drop into the anode melt collection area 305.

[0044] For purposes of illustration, as embodied herein, the walls of the cell 301 can define a first anode structure portion 321 and a second anode structure portion 322 can form a barrier that holds the impure aluminum 312 between the first anode structure portion 321 and the second anode structure portion 322. As described above, the system can incorporate multiple cells, and the walls of the cells can, for example, define a first anode structure portion for a first cell and a cathode structure portion for a second adjacent cell. The second anode structure portion can be positioned relative to the first anode structure portion 321 to achieve a desired thickness and volume of the impure aluminum 312 in the anode reservoir 323. As embodied herein, the anode reservoir 323 can reserve the impure aluminum 312. For example, as embodied herein, the anode reservoir 323 can reserve only impure aluminum and have no liquid electrolyte therein.

[0045] The second anode structure portion 322 can be constructed from any suitable material. By way of example and not limitation, for purposes embodied herein, the second anode structure portion 322 can be constructed from a porous material. For example, the second anode structure portion 322 can be constructed from graphite, carbon fiber cloth, porous TiB 2 and / or foam. For example, and as embodied herein, the second anode material 322 can include a porous carbon material. Additionally or alternatively, holes or passages can be defined in the second anode material 322.

[0046] The material of the second anode material 322 can be selected to provide a desired impure aluminum flow rate from the anode reservoir 323 to the anode melt collection area 305. For example, as embodied herein, the second anode structure portion 322 can be impregnated with impure aluminum 312 as the impure aluminum flows through the second anode structure portion 322. As embodied herein, a voltage and / or current can be applied between the impure aluminum 312 and the cathode, and aluminum ions from the impure aluminum 312 can migrate through the liquid electrolyte 110 to the cathode structure.

[0047] The porosity and / or ease with which the impure aluminum 312 may flow through the second anode structure portion 322 may be selected based on the desired system performance. For example, a more porous material and / or a material that allows for greater diffusion of the impure aluminum 312 may be used for the second anode structure portion 322 to support higher aluminum flow rates, higher current densities, and increased collection rates of refined aluminum at the cathode structure 309. Additionally or alternatively, a less porous material and / or a material that allows for less diffusion of the impure aluminum 312 may be used for the second anode structure portion 322 to support lower aluminum flow rates, lower current densities, and lower collection rates of refined aluminum at the cathode structure 309.

[0048] As will be further embodied herein, the anode structure 308 can include an anode reservoir bottom 325. By way of example, as will be embodied herein, the anode reservoir bottom portion 325 can prevent impure aluminum 312 from flowing through the anode reservoir bottom portion 325. For example, the anode reservoir bottom portion 325 can be constructed of a non-porous material. Additionally or alternatively, as will be further embodied herein, the anode reservoir bottom can separate and electrically insulate the anode from the anode melt collection region 305.

[0049] As embodied herein, the impure aluminum 312 can be the anode of the system 300. For example, the first anode structure portion 321 and the second anode structure portion 322 can be composed of a non-conductive material or a material having a lower conductance than the impure aluminum 312. Additionally or alternatively, leads in electrical communication with the impure aluminum 312 can be used to apply a voltage and / or current to the impure aluminum 312.

[0050] As discussed above, the liquid electrolyte 310 has an electrolyte density, and the impure aluminum 312 has an impure aluminum density that is greater than the electrolyte density. The flow of the impure aluminum 112 from the top 303 to the anode melt collection area 305 is related to, among other things, the relative densities of the liquid electrolyte 310 and the impure aluminum 312. As described further herein, the refined aluminum 313 captured in the cathode structure 309 has a refined aluminum density that is greater than the electrolyte density. As a result of the relative densities of the liquid electrolyte 310, the impure aluminum in the anode melt collection area 305, and the refined aluminum in the cathode melt collection area 306, the liquid electrolyte 310 can form a layer in the chamber 302 above the molten aluminum contained in the anode melt collection area 305 and the cathode melt collection area 306, respectively. As embodied herein, an interface 316 can be defined between the liquid electrolyte 310 and the molten aluminum contained in the anode melt collection area 305 and the cathode melt collection area 306, respectively. As further embodied herein, the divider 307 can be configured to extend from the bottom of the cell to a height above the interface 316 to maintain separation between the impure aluminum contained in the anode melt collection region 305 and the refined aluminum contained in the cathode melt collection region 306. As further embodied herein, the interface 316 can be below the cathode structure 309.

[0051] As embodied herein, the region of the chamber 302 between the anode structure 308 and the cathode structure 309 can be free of barriers or membranes or other structures that may impede the flow of electrolyte 310 between the anode structure 310 and the cathode structure 309. Having a free flow of liquid electrolyte 310 within the chamber 302 and between the anode structure 310 and the cathode structure 309 can be desirable for the steady state dynamics of the system 300.

[0052] The cathode structure 309 is configured to capture molten refined aluminum 313 having a refined aluminum density greater than the electrolyte density from the impure aluminum 312 via the liquid electrolyte 310. The cathode structure 309 further defines a cathode flow path through which the refined aluminum 313 can flow from the top 303 to the cathode molten material collection area 306. As described above, the cathode structure 309 is disposed at the top of the chamber 302 and vertically aligned above the cathode molten material collection area 306. The cathode structure 309 is configured to capture molten refined aluminum 313 having a refined aluminum density greater than the electrolyte density from the impure aluminum via the liquid electrolyte 310.

[0053] The cathode structure 309 may be constructed of any suitable material. By way of example and not limitation, the material of the cathode structure may include tungsten or graphite. Additionally or alternatively, as embodied herein, the cathode structure 309 may be constructed of aluminum. The cathode structure 309 may have any suitable shape and configuration. For purposes of example, as embodied herein, the surface of the cathode structure 309 may include one or more grooves defined therein, and the refined aluminum 313 may be deposited within the grooves of the cathode structure 309. For example, the cathode structure 309 may include vertically extending grooves defined in the surface of the cathode structure. The inclusion of grooves or channels in the cathode structure may provide additional stability to the layer of aluminum formed on the cathode structure during operation of the system. Additionally or alternatively, the inclusion of grooves or channels in the anode, cathode structure may reduce the possibility of aluminum bridging between the anode and the cathode. For example, but not by way of limitation, the inclusion of grooves or channels in the cathode structure can reduce the likelihood of aluminum bridging between the anode and cathode when the distance between the anode and cathode structures is reduced, as described further herein. As discussed above, the purified aluminum 313 can be collected on the cathode structure 309 and can flow along the vertically oriented cathode structure 309 and drip into the cathode melt collection area 306.

[0054] 3A illustrates another purification system 300a in accordance with the disclosed subject matter. In accordance with the disclosed subject matter, purification system 300a includes a cell 301a defining a chamber 302a. Chamber 302a has an upper portion 303a and a lower portion 304a. Lower portion 304a includes a cathode melt collection area 306a defined therein.

[0055] The chamber 302a further includes an anode structure 308a vertically aligned above the cathode melt collection area 306a. The cathode structure 309a is disposed at the top 303a of the chamber 302a and vertically aligned above the cathode melt collection area 306a. A liquid electrolyte 310a is disposed within the chamber 302a in fluid communication with the anode structure 308a and the cathode structure 309a. The liquid electrolyte 310a has an electrolyte density.

[0056] The anode structure 308a is configured to receive impure aluminum 312a in a molten state having an impure aluminum density greater than the electrolyte density. The cathode structure 309a is configured to capture refined aluminum 313a in a molten state having a refined aluminum density greater than the electrolyte density from the impure aluminum via the liquid electrolyte 310a. The cathode structure 309a further defines a cathode flow path through which the refined aluminum 313a can flow from the top 303a to the cathode melt collection area 306a. As embodied herein, the cathode flow path can include a layer of molten refined aluminum 313a along the surface of the cathode structure 309a. As embodied herein, the refined aluminum 313a collected on the cathode structure 309a can flow along the vertically oriented cathode structure 309a and drip into the cathode melt collection area 306a.

[0057] As embodied herein, the anode structure 308a can include a first anode structure portion 321a and a second anode structure portion 322a with an anode reservoir 323a therebetween. The anode structure 308a can receive impure aluminum 312a in the anode reservoir 323a. As further embodied herein, a first side of the second anode structure portion 322a can be in fluid communication with the impure aluminum 312a and a second side of the second anode structure portion 322a can be in fluid communication with the liquid electrolyte 310a. As embodied herein, the second anode structure portion 322a can be porous. For example, as embodied herein, the pores of the second anode structure portion 322a can be sized to prevent impure aluminum from flowing through the pores and to allow aluminum ions to pass through the pores.

[0058] For illustrative purposes and as embodied herein, the walls of the cell 301a can define a first anode structure portion 321a, and the second anode structure portion 322a can form a barrier between the first anode structure portion 321a and the second anode structure portion 322a to retain the impure aluminum 312a. As described above, the system can incorporate multiple cells, and the walls of the cells can, for example, define a first anode structure portion for a first cell and a cathode structure portion for a second adjacent cell. The second anode structure portion can be positioned relative to the first anode structure portion 321a to achieve a desired thickness and volume of the impure aluminum 312a in the anode reservoir 323a. As embodied herein, the anode reservoir 323a can reserve the impure aluminum 312a. For example, as embodied herein, the anode reservoir 323a may hold only impure aluminum and have no liquid electrolyte therein.

[0059] The second anode structure portion 322a can be composed of any suitable material. By way of example and not limitation, as embodied herein, the second anode structure portion 322a can be composed of a porous material.

[0060] As will be further embodied herein, the anode structure 308a can include an anode reservoir bottom 325a. For purposes of illustration, and as will be further embodied herein, the anode reservoir bottom portion 325a can prevent impure aluminum 312a from flowing through the anode reservoir bottom portion 325a. For example, the anode reservoir bottom portion 325a can be constructed of a non-porous material. Additionally or alternatively, as will be further embodied herein, the anode reservoir bottom portion 325a can separate and electrically insulate the anode structure 308a from the cathode melt collection region 306a.

[0061] As embodied herein, the system 300a may include a pump 316a. The pump 316a may be used to remove the impure aluminum material 312a from the reservoir 323a. By way of example and not limitation, transferring the impure aluminum 312a from the anode structure 308a may prevent the accumulation and / or concentration of impurities in the impure aluminum 312a received at the anode structure, as described further herein. For example, the impure aluminum 312a may be transferred from the anode structure 308a to a second cell, where the transferred impure aluminum is received by a second anode structure, as described further herein.

[0062] In accordance with one aspect of the disclosed subject matter, as embodied herein, an aluminum refining system may include one or more cells. For purposes of illustration and description, reference is made to an exemplary system 400 depicted in FIG. 4. In accordance with the disclosed subject matter, the refining system 400 comprises a cell defining a first chamber 402a. The chamber 402a has an upper portion 403 and a lower portion 404. The lower portion 404 includes a cathode melt collection area 406a. As embodied herein, the lower portion 404 may further include an anode melt collection area 405. The anode melt collection area 405 may be separated from the cathode melt collection area 406a by a partition 407a disposed therebetween. The system 400 further includes an anode structure 408 disposed at an upper portion of the chamber 402a and vertically aligned above the lower portion 404. As embodied herein, the anode structure 408 may be disposed at the top of the chamber 402a and vertically aligned above the anode melt collection area 405. The cathode structure 409a is disposed at the top portion of the chamber 402a and vertically aligned above the cathode melt collection area 406a. A liquid electrolyte 410 is disposed within the chamber 402a in fluid communication with the anode structure 408 and the cathode structure 409a. The cathode structure 409a is configured to capture refined aluminum 413 in a molten state, having a refined aluminum density greater than the electrolyte density, from the impure aluminum 412 via the liquid electrolyte 410. The cathode structure 409a further defines a cathode flow path through which the refined aluminum 413 can flow from the top 403 to the cathode melt collection area 406a. As embodied herein, the anode structure 408 can define an anode flow path through which molten impure aluminum 412, having an impure aluminum density greater than the electrolyte density, can flow from the top into the anode melt collection area 405.

[0063] For purposes of illustration, as embodied herein, the system 400 further includes a cell defining a second chamber 402b. The chamber 402b has an upper portion 403 and a lower portion 404. The lower portion 404 includes a cathode melt collection area 406b. As embodied herein, the lower portion 404 can further include an anode melt collection area 405. The anode melt collection area 405 can be separated from the cathode melt collection area 406b by a partition 407b disposed therebetween. The system 400 further includes an anode structure 408 disposed at the upper portion of the chamber 402b and vertically aligned above the lower portion 404. As embodied herein, the anode structure 408 can be disposed at the upper portion of the chamber 402b and vertically aligned above the anode melt collection area 405. The cathode structure 409b is disposed at the top of the chamber 402b and vertically aligned above the cathode melt collection area 406b. The liquid electrolyte 410 is disposed within the chamber 402b in fluid communication with the anode structure 408 and the cathode structure 409b. The cathode structure 409b is configured to capture refined aluminum 413 in a molten state having a refined aluminum density greater than the electrolyte density from the impure aluminum 412 via the liquid electrolyte 410. The cathode structure 409b further defines a cathode flow path through which the refined aluminum 413 can flow from the top 403 to the cathode melt collection area 406b. As embodied herein, the anode structure 408 defines an anode flow path through which the impure aluminum 412 in a molten state having an impure aluminum density greater than the electrolyte density can flow from the top to the anode melt collection area 405.

[0064] For purposes of illustration, the chambers 402a and 402b may include separate anode structures. Additionally or alternatively, as embodied herein, the anode structure 408 may be an anode structure common to the chambers 402a and 402b and the cathode structures 409a and 409b. For purposes of illustration and as embodied herein, the anode structure 408 may include a first anode structure portion 421 and a second anode structure portion 422 with an anode reservoir 423 therebetween. The anode structure 408 may be configured to receive impure aluminum 412 in the anode reservoir 423. As embodied herein, the anode flow path may extend from the anode reservoir 423 through both the first anode structure portion 421 and the second anode structure portion 422 to the anode melt collection region 405. For example, as embodied herein, the first anode structure portion 421 and the second anode structure portion 422 can be made of a porous material and the impure aluminum 412 can flow therethrough.

[0065] As further embodied herein, the anode structure 408 can include an anode reservoir bottom 425. By way of example, and as embodied herein, the anode reservoir bottom portion 425 can prevent impure aluminum 412 from flowing through the anode reservoir bottom portion 425. For example, the anode reservoir bottom 425 can be constructed from a non-porous material.

[0066] The inclusion of multiple chambers in system 400 provides benefits such as, for example, redundancy. For example, if chamber 402a and / or cathode 409a require maintenance, purification can continue in chamber 402b. Additionally or alternatively, both chambers 402a and 402b can be operated simultaneously, thereby increasing the aluminum purification rate of the system. It is understood that system 400 can include two or more chambers and / or anode structure / cathode structure pairs. Additionally or alternatively, chambers and / or anode structure / cathode structure pairs can be operated in series to achieve the desired aluminum purification, as described above. For example, but not limited to, purified aluminum 413 from cathode molten material collection area 406a and / or cathode molten material collection area 406b can be reintroduced to another anode structure in the system and subjected to further purification, as further described herein.

[0067] Additionally or alternatively, the impure aluminum from the anode structure can be transferred to another cell for further purification. For example, the impure aluminum can be transferred from the anode structure of the first cell to the anode structure of the second cell. By way of example and not limitation, the impure aluminum can be transferred from the anode reservoir. Additionally or alternatively, the impure aluminum can be transferred from the anode melt collection area. The impure aluminum can be transferred from the anode structure of the first cell to the anode structure of the second cell using standard metal transfer methods. For example, but not by way of limitation, the impure aluminum can be periodically siphoned from the anode structure using standard metal transfer methods. Additionally or alternatively, the impure aluminum can be constantly drained from the anode structure to a collection well and / or water tank for removal to another anode structure, etc. Transferring the impure aluminum from the anode structure can prevent accumulation and / or concentration of impurities in the impure aluminum received at the anode structure.

[0068] The aluminum refining cells can be operated in series at different temperatures. For example, as embodied herein, the temperature of the aluminum refining cells can be selected based on the aluminum concentration in the impure aluminum introduced to the cells. For purposes of illustration and not limitation, a first cell can have a first cell temperature, and the second cell can have a second cell temperature, and the second cell temperature can be higher than the first cell temperature. For example, and not by way of limitation, the cell temperature can be a temperature between about 640° C. and about 900° C., depending on the aluminum concentration in the impure aluminum introduced to the cells. As used herein, cell temperature refers to the temperature of the liquid electrolyte in the cell. A higher aluminum refining cell temperature can be beneficial for refining impure aluminum having a lower aluminum concentration (i.e., having a higher impurity concentration). For example, if the impure aluminum has a low aluminum concentration, a higher temperature can be used to keep the impure aluminum in a liquid state. As embodied herein, impure aluminum having a first concentration of aluminum can be introduced to a first cell and received by an anode structure of the first cell. As aluminum is extracted from the impure aluminum in the anode structure and captured in the cathode structure of the first cell, the concentration of aluminum in the impure aluminum in the anode structure of the first cell can be reduced to a second, lower concentration of aluminum. The impure aluminum having the second, lower concentration of aluminum can be transferred from the anode structure of the first cell to the second cell such that the second anode structure receives the impure aluminum. As embodied herein, the second cell can have a higher temperature than the first cell to further purify the impure aluminum having the second, lower concentration of aluminum.

[0069] For purposes of explanation and not limitation, reference is made to an exemplary aluminum refining system 500 depicted in FIG. 5. In accordance with the disclosed subject matter, the refining system 500 comprises a first cell defining a first chamber 502a. The chamber 502a has an upper portion 503 and a lower portion 504. The lower portion 504 includes a cathode melt collection area 506a. As embodied herein, the lower portion 504 may further include an anode melt collection area 505a. The anode melt collection area 505a may be separated from the cathode melt collection area 506a by a partition 507a disposed therebetween. The system 500 further includes an anode structure 508a disposed at the upper portion of the chamber 502a and vertically aligned above the lower portion 504. As embodied herein, the anode structure 508a may be disposed at the upper portion of the chamber 502a and vertically aligned above the anode melt collection area 505a. The cathode structure 509a is disposed at the top of the chamber 502a and vertically aligned above the cathode melt collection area 506a. A liquid electrolyte 510a is disposed within the chamber 502a in fluid communication with the anode structure 508a and the cathode structure 509a.

[0070] The anode structure 508a is configured to receive impure aluminum 512a in a molten state having an impure aluminum density greater than the electrolyte density. As embodied herein, the anode structure 508a can include a first anode structure portion 521a and a second anode structure portion 522a with an anode reservoir 523a therebetween. The anode structure 508a can receive the impure aluminum 512a in the anode reservoir 523a. As embodied herein, the anode structure 508a can define an anode flow path through which the impure aluminum 512a in a molten state having an impure aluminum density greater than the electrolyte density can flow from the top portion 503 to the anode melt collection area. As embodied herein, the anode flow path can extend from the anode reservoir 523a through the second anode structure portion 522a to the anode melt collection area 505a.

[0071] The cathode structure 509a is configured to capture refined aluminum 513a in a molten state, the refined aluminum having a density greater than the electrolyte density, from the impure aluminum 512a through the liquid electrolyte 510a. The cathode structure 509a further defines a cathode flow path through which the refined aluminum 513a can flow from the top 503 to the cathode melt collection area 506a.

[0072] As embodied herein, impure aluminum 512a having a first concentration of aluminum can be introduced into a first cell anode structure 508a. As aluminum is extracted from the impure aluminum 512a in the anode structure and captured in the first cell cathode structure 509a, the concentration of aluminum in the impure aluminum 512a in the first cell anode structure 508a can be reduced to a second, lower concentration of aluminum. As embodied herein, the impure aluminum 512a having the second, lower concentration of aluminum can be transported from the first cell anode structure 508a to a second cell where the impure aluminum is received by a second anode structure 508b.

[0073] As embodied herein, the system 500 further includes a second cell defining a second chamber 502b. The chamber 502b has an upper portion 503 and a lower portion 504. The lower portion 504 includes a cathode melt collection area 506b. As embodied herein, the lower portion 504 may further include an anode melt collection area 505b. The anode melt collection area 505b may be separated from the cathode melt collection area 506b by a partition 507b disposed therebetween. The system 500 further includes a second anode structure 508b disposed at the upper portion of the second chamber 502b and vertically aligned above the lower portion 504. As embodied herein, the second anode structure 508b may be disposed at the upper portion of the chamber 502a and vertically aligned above the anode melt collection area 505b. A cathode structure 509b is disposed at the top of the chamber 502b and vertically aligned above the cathode melt collection area 506b. A liquid electrolyte 510b is disposed within the chamber 502b in fluid communication with the anode structure 508b and the cathode structure 509b.

[0074] The anode structure 508b is configured to receive impure aluminum 512b in a molten state having an impure aluminum density greater than the electrolyte density. As embodied herein, the anode structure 508b can receive impure aluminum 512a having a second, lower aluminum concentration from the anode structure 508a of the first cell. The aluminum can be transferred from the first anode structure 508a to the second anode structure 508b using any suitable method. For purposes of illustration, as embodied herein, the pump 516 can transfer the aluminum from the first anode structure 508a to the second anode structure 508b, as indicated by arrow 541. As embodied herein, the anode structure 508b can include a first anode structure portion 521b and a second anode structure portion 522b with an anode reservoir 523b therebetween. The anode structure 508b can receive the impure aluminum 512b in the anode reservoir 523b. As embodied herein, the anode structure 508b can define an anode flow path through which the impure aluminum 512b in a molten state, having an impure aluminum density greater than the electrolyte density, can flow from the top portion 503 to the anode melt collection area. As embodied herein, the anode flow path can extend from the anode reservoir 523b through the second anode structure portion 522b to the anode melt collection area 505b.

[0075] The cathode structure 509b is configured to capture refined aluminum 513b in a molten state, having a refined aluminum density greater than the electrolyte density, from the impure aluminum 512b through the liquid electrolyte 510b. The cathode structure 509b further defines a cathode flow path through which the refined aluminum 513b can flow from the top 503 to the cathode melt collection region 506b.

[0076] As embodied herein, the first cell and first chamber 502a can be operated at a first cell temperature, and the second cell and second chamber 502b can be operated at a second cell temperature. As embodied herein, the second cell temperature can be higher than the first cell temperature. For example, as described above, the impure aluminum 512b received at the second anode structure 508b can have a lower aluminum concentration compared to the impure aluminum 512a received at the first anode structure 508a. The cell temperature can be selected based on the concentration of the impure aluminum to be purified, as described above.

[0077] Operating aluminum purification cells in series at temperatures selected according to the aluminum concentration in the impure aluminum is beneficial to system efficiency: for example, the first cell, with impure aluminum having a higher concentration of aluminum, can be operated at a lower temperature and require less energy.

[0078] The temperature of the aluminum refining cell can be controlled using any suitable method. For purposes of illustration and not limitation, the wall of the aluminum refining cell can include a heat transfer system for controlling the temperature of the aluminum refining cell. By way of example and not limitation, the wall of the aluminum refining cell can include two plates with a gap defined therebetween. The plate of the cell wall can include, for example, steel or a high temperature alloy. Additionally or alternatively, the plate of the cell wall can include a graphite layer facing the interstitial space. Additionally or alternatively, a coiled tube can be placed in the interstitial space. For example, the tube can be sinusoidally wound within the interstitial space. The remainder of the interstitial space can be filled with a conductive material, such as, for example, graphite powder. Air or other gas can be flowed through the tube to control the temperature of the cell. For example, heated air or other gas can be flowed through the tube to increase the temperature of the cell, and cooled air can be flowed through the tube to decrease the temperature of the cell. As embodied herein, the aluminum refining cell can be heated to a desired temperature for cell start-up. Additionally or alternatively, the aluminum refining cell may be cooled to maintain a desired operating temperature during steady-state operation of the aluminum refining cell.

[0079] The disclosed subject matter further includes a method for refining aluminum. The method according to the disclosed subject matter includes operating an aluminum refining system having any of the features described above. The method according to the disclosed subject matter further includes the step of introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into a chamber for receipt by an anode structure, the anode structure defining an anode flow path through which the impure aluminum can flow from the top to an anode melt collection area. The method further includes the step of capturing refined aluminum in a molten state having a refined aluminum density greater than the electrolyte density in a cathode structure via a liquid electrolyte, the cathode structure defining a cathode flow path through which the refined aluminum can flow from the top to a cathode melt collection area. The method further includes the step of collecting the refined aluminum discharged from the cathode structure in the cathode melt collection area.

[0080] For purposes of explanation and not limitation, reference is made to the exemplary aluminum refining method of FIG. 2. In accordance with the disclosed inventive subject matter, the method 200 includes step 201 of operating an aluminum refining system. For purposes of illustration, as embodied herein, the aluminum refining system may include the exemplary system 100 of aluminum refining as shown in FIG. 1. The method according to the disclosed inventive subject matter may be used with a system having any of the features described herein. The method further includes step 202, in which impure aluminum 112 having an impure aluminum density in a molten state greater than the electrolyte density is introduced into the chamber 102 and received by the anode structure 108. As shown in step 203, refined aluminum 113 is captured from the impure aluminum 112 via the liquid electrolyte 110 into the cathode structure 109. As embodied herein, a voltage and / or current can be applied between the impure aluminum 112 of the anode structure 108 and the refined aluminum 113 of the cathode structure 109, and aluminum ions can flow from the anode structure 108 to the cathode structure 109 via the liquid electrolyte 110. In step 204, the refined aluminum 113 is released from the cathode structure 109 and collected in the cathode molten collection area 106.

[0081] As described above, the system 100 may include an anode melt collection area 105 disposed below the anode structure 108. As embodied herein, the method may further include removing the impure molten aluminum 112 from the anode melt collection area 105 via an outlet 114 in fluid communication with the first molten material collection area 105. As described above, the removed impure molten aluminum 112 may be reintroduced into the chamber 102 and the anode structure 108, such as by using a pump 116. Additionally or alternatively, as described above, the system 100 may include two or more anode structures, and introducing the impure molten aluminum 112 into the chamber 102 may further include introducing the impure molten aluminum 112 into a second anode structure. As embodied herein, the system 100 includes one anode structure 108, but may also include additional anode structures. The number of cells and anode structures may be selected based on the desired performance characteristics of the purification system. In accordance with the disclosed subject matter, the cathode structure 109 is disposed at the top of the chamber in vertical alignment above the cathode melt collection area 106. As embodied herein, the system 100 includes one cathode structure 109, although additional cathode structures may be included. The number of cells and cathode structures may be selected based on the desired performance characteristics of the purification system.

[0082] As described above, the cathode structure 109 defines a cathode flow path through which the refined aluminum can flow from the top 103 to the cathode melt collection area 106. For example, as embodied herein, the refined aluminum can flow down the cathode structure 109 and drip into the cathode melt collection area 106. As embodied herein, the refined aluminum 113 can be removed from the cathode molten material collection area 106 via an outlet 115 in fluid communication with the second molten material collection area 106.

[0083] Systems and methods according to the disclosed subject matter can be used to collect high quality refined aluminum. By way of example, systems according to the disclosed subject matter can be used to process impure aluminum having at least 80 wt.% aluminum and produce aluminum having at least 99 wt.% aluminum. As embodied herein, refined aluminum can have 99.99 wt.% aluminum.

[0084] Additionally, systems and methods according to the disclosed subject matter can be used to efficiently refine aluminum. The energy consumption of an aluminum refining system can be expressed in kilowatt-hours per kilogram of aluminum produced (kWh / kg). By way of example, a system according to the disclosed subject matter can capture the refined aluminum with an energy consumption of about 1.5-7 kWh / kg of the refined aluminum captured at the cathode structure. A system according to the disclosed subject matter can provide improved efficiency. For example, a system according to the disclosed subject matter can include a more conductive electrolyte and the distance between the anode structure and the cathode structure can be smaller, improving system efficiency. For example, a liquid electrolyte having an electrolyte density less than the density of refined aluminum can be more conductive than a liquid electrolyte having an electrolyte density greater than the density of refined aluminum, such as, for example, a liquid electrolyte used in a HOOP cell configuration.

[0085] Example 1: Approximately 540 g of impurity Al was processed in a system having a configuration similar to that of the exemplary system 400 depicted in FIG. 4. In this test system, the anode reservoir bottom 435 extended to the bottom of the chamber to divide the anode melt collection area 405 into two separate collection areas, one for each of chambers 402a and 402b. The system included an anode structure having a porous second anode structure portion. The second anode structure portion was constructed of graphite felt. Additionally, the liquid electrolyte used was 66% LiF and 34% Na 3 AlF 6 The density of this liquid electrolyte was approximately 2.1 g / cm 3 The system included an anode-cathode distance of about 4 cm. The first chamber utilized a tungsten cathode structure on a first side of the anode structure, and the second chamber utilized a graphite cathode structure on a second side of the anode structure. The cell temperature in both chambers was about 700° C. Impure aluminum was added to the system and received at the anode structure. The impure aluminum was about 95.3% Al. Refined aluminum was collected at a molten material collection area. The refined aluminum collected at the molten material collection area contained fewer impurities compared to the impure aluminum received at the anode structure of the exemplary system. As embodied herein, the reduction in impurities was as follows: Cu was reduced by more than about 97%, Fe by about 93%, Mn by about 98%, Si by about 96%, and Zn by more than about 96%.

[0086] Additionally, the systems and methods according to the disclosed subject matter can be used without the need to modify the density of the impure aluminum feed material. For example, in a HOOP cell configuration, the impure aluminum feed material is often alloyed with another material, such as copper, to increase the density of the impure aluminum feed material. Alloying the impure aluminum may be required in a HOOP cell configuration that relies on a liquid electrolyte that has a density less than the impure aluminum feed material and greater than the density of refined aluminum. The systems and methods according to the disclosed subject matter include a liquid electrolyte that has a density less than the impure aluminum feed material and less than refined aluminum, which can alleviate the need to alloy the impure aluminum feed material or modify its density before introducing it into the refinery system.

[0087] Additionally, the systems and methods according to the disclosed subject matter can be configured for continuous operation. Systems and methods for continuous operation may provide advantages over other systems, such as HOOPS cells, which may require batch processing and associated interruptions in aluminum refining. For example, during operation of a system based on a HOOPS cell configuration, the aluminum of the anode layer at the bottom of the refining cell may become depleted over time, necessitating periodic replacement of the aluminum-depleted anode layer with new impure aluminum and copper alloy material. Replacement of the depleted aluminum anode layer may require a temporary suspension of aluminum refining, reducing the efficiency of the overall system.

[0088] The periodic replacement and / or batch operation of a HOOP cell-based system can be avoided using the system and method according to the disclosed inventive subject matter. For example, as embodied herein, the anode structure can be configured to continuously receive impure aluminum in a molten state, such that the impure aluminum can flow continuously along the anode flow path from the top to the anode melt collection area. As embodied herein, the impure aluminum can be continuously introduced and flowed along the anode flow path, thus avoiding replacement of depleted input material with new impure aluminum input material. As further embodied herein, the cathode structure can be configured to continuously capture the refined aluminum in a molten state. By avoiding periodic replacement and / or batch operation, the efficiency of the overall system can be increased.

[0089] It should be understood that the term "impure aluminum" as used herein can encompass a wide variety of feed materials that contain aluminum as well as other materials. By way of example, impure aluminum feed materials can include aluminum, magnesium, lithium, and other metallic materials. Described herein are systems and methods for recovering refined aluminum from impure aluminum feed materials. In addition to capturing refined aluminum from impure aluminum feed materials, it may be desirable to capture additional refined metals present in the feed material (e.g., capture refined magnesium or lithium). In this regard, for example, additional processing that can be performed before or after the impure aluminum material is introduced into the systems and methods described herein for capturing refined aluminum can be used to capture and separate the additional materials of interest from the impure aluminum feed material. Such additional processing can be performed, for example, using the chambers disclosed herein for capturing refined aluminum or the like.

[0090] In addition to the specific embodiments claimed below, the disclosed subject matter is also directed to other embodiments having any other possible combinations of the dependent features claimed below and the features disclosed above. Thus, the specific features presented in the dependent claims and disclosed above can be combined with each other in other manners within the scope of the disclosed subject matter, such that it should be recognized that the disclosed subject matter is also specifically directed to other embodiments having any other possible combinations. Thus, the foregoing description of specific embodiments of the disclosed subject matter has been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit the disclosed subject matter to the disclosed embodiments.

[0091] It will be apparent to those skilled in the art that various modifications and variations can be made in the method and system of the disclosed subject matter without departing from the spirit or scope of the disclosed subject matter. Thus, it is intended that the disclosed subject matter cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. 1. An aluminum refining system comprising: a cell defining a chamber having an upper portion and a lower portion, the lower portion including a cathode melt collection area defined therein; an anode structure disposed in the upper portion of the chamber and vertically disposed above the lower portion; a cathode structure disposed in the upper portion of the chamber and vertically disposed above the cathode melt collection area; and a liquid electrolyte in the chamber in fluid communication with the anode structure and the cathode structure, the liquid electrolyte having an electrolyte density; Equipped with the anode structure is configured to receive the impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density; and and wherein the cathode structure is configured to capture the refined aluminum in a molten state, the refined aluminum having a refined aluminum density greater than the electrolyte density, from the impure aluminum via the liquid electrolyte, the cathode structure further defining a cathode flow path through which the refined aluminum can flow from a top portion to the cathode melt collection area.

2. 2. The aluminum refining system of claim 1, wherein the anode structure includes a first anode structure portion and a second anode structure portion with an anode reservoir therebetween, the anode structure configured to receive the impure aluminum in the anode reservoir.

3. 3. The aluminum refining system of claim 2, wherein a first side of the second anode structure portion is in fluid communication with the impure aluminum and a second side of the second anode structure portion is in fluid communication with the liquid electrolyte.

4. 4. The aluminum refining system according to claim 2, wherein the second anode structure portion comprises pores.

5. 5. The aluminum refining system of claim 4, wherein the pores in the second anode structure portion are sized to prevent the impure aluminum from flowing through the pores and to allow aluminum ions to pass through the pores.

6. 6. The aluminum refining system of claim 1, wherein the lower portion further comprises an anode melt collecting area, and the anode structure is vertically aligned with an upper portion of the anode melt collecting area.

7. 7. The aluminum refining system of claim 6, wherein the cathode melt collection area is separated from the anode melt collection area by a partition disposed therebetween.

8. 8. The aluminum refining system of claim 6, wherein the anode structure defines an anode flow path through which the impure aluminum in a molten state can flow from the top to the anode melt collection area.

9. 9. An aluminium refining system according to any one of claims 2 to 8, wherein the second anode structure portion is configured to be impregnated with the impure aluminium.

10. 10. The aluminum refining system of claim 8, wherein the anode flow path extends from the anode reservoir through the second anode structure portion to the anode melt collection area.

11. 11. The aluminum refining system according to claim 2, wherein the second anode structure portion is made of a porous carbon material.

12. In the aluminum refining system according to any one of claims 2 to 11, the second anode structure part is made of graphite, carbon fiber cloth, porous TiB ２ and a foam.

13. 13. An aluminium refining system according to any one of the preceding claims, wherein the anode structure is made of an aluminium wettable material.

14. 14. The aluminum refining system of claim 13, wherein the aluminum-wetting material comprises TiB2 on at least a surface of the anode. ２ 1. An aluminum refining system comprising:

15. 15. The aluminum refining system of claim 14, wherein the TiB ２ is an electroplated layer on said surface of said anode structure.

16. 16. The aluminum refining system according to claim 14, wherein the anode structure is made of TiB ２ An aluminum refining system comprising a layer of graphite disposed thereon.

17. 17. An aluminium refining system according to any one of claims 1 to 16, wherein said cathode structure is made of said aluminium-wettable material.

18. 18. An aluminum refining system according to any one of the preceding claims, wherein the cathode structure includes one or more grooves defined therein.

19. 19. The aluminum refining system according to any one of claims 1 to 18, wherein the liquid electrolyte comprises LiF and AlF3.

20. In the aluminum refining system according to any one of claims 1 to 19, the liquid electrolyte further comprises NaF, KF, or CaF ２ 1. An aluminum refining system comprising:

21. 21. The aluminum refining system according to any one of claims 1 to 20, wherein the liquid electrolyte is about 2.7 g / cm ３ An aluminum refining system having a density of less than 1000 nm.

22. 22. The aluminum refining system of claim 1, wherein the cathode structure is configured to capture the refined aluminum having a higher wt. % Al than the impure aluminum introduced to the anode structure.

23. 23. The aluminum refining system of any one of claims 1 to 22, wherein the cathode structure is configured to capture the refined aluminum with an energy consumption of about 1.5 to 7 kWh / kg of the refined aluminum captured in the cathode structure.

24. 24. The aluminum refining system of any one of claims 1 to 23, further comprising an outlet in fluid communication with the anode melt collection area for removing impure molten aluminum.

25. 25. The aluminum refining system of any one of claims 1 to 24, further comprising an outlet in fluid communication with the cathode melt collection area for removing refined aluminum.

26. 26. The aluminum refining system of any one of claims 1 to 25, wherein the distance between the anode structure and the cathode structure is from about 2 mm to about 5 cm.

27. 27. The aluminum refining system according to claim 7, wherein an interface is defined between the liquid electrolyte and molten aluminum contained in each of the anode melt collection area and the cathode melt collection area, and the divider extends into the chamber from a bottom of the cell to a height above the interface.

28. 28. The aluminum refining system according to any one of claims 7 to 27, wherein the liquid electrolyte has a top surface, and the divider does not contact the top surface of the liquid electrolyte.

29. 29. The aluminum refining system of claim 1, wherein the interface is defined between the liquid electrolyte and molten aluminum contained in the cathode melt collection area, the interface being below the cathode structure.

30. 30. An aluminium refining system according to any one of claims 1 to 29, wherein the anode structure is configured to continuously receive the impure aluminium in a molten state and the cathode structure is configured to continuously capture the refined aluminium in a molten state.

31. 31. An aluminium refining system according to any preceding claim, wherein the liquid electrolyte is free to flow between the anode structure and the cathode structure.

32. 1. A method for refining aluminum, comprising the steps of: operating a purification system, said purification system comprising: a cell defining a chamber having an upper portion and a lower portion, the lower portion including a cathode melt collection area defined therein; an anode structure disposed in the upper portion of the chamber and vertically aligned above the lower portion; a cathode structure disposed in an upper portion of the chamber vertically disposed above a molten material collection area; and a liquid electrolyte in the chamber in fluid communication with the anode structure and the cathode structure, the liquid electrolyte having an electrolyte density; operating the purification system, introducing molten impure aluminum having an impure aluminum density greater than the electrolyte density into a chamber for receipt by the anode structure; capturing molten refined aluminum having a refined aluminum density greater than the electrolyte density from the impure aluminum via the liquid electrolyte in the cathode structure, the cathode structure defining a cathode flow path through which the refined aluminum can flow from the top to the cathode melt collection area; collecting the purified aluminum discharged from the cathode structure in the cathode melt collection area; A method for refining aluminum comprising the steps of:

33. 33. The aluminum refining method of claim 32, wherein the anode structure includes a first anode structure portion, a second anode structure portion, and an anode reservoir therebetween, the anode structure configured to receive the impure aluminum in the anode reservoir.

34. 34. The aluminum refining method of claim 33, wherein a first side of the second anode structure portion is in fluid communication with the impure aluminum and a second side of the second anode structure portion is in fluid communication with the liquid electrolyte.

35. The method of any one of claims 33 to 34, wherein the second anode structure portion comprises pores.

36. 36. The method of claim 35, wherein the pores in the second anode structure portion are sized to prevent the impure aluminum from flowing therethrough and to allow aluminum ions to pass therethrough.

37. 37. The method of refining aluminum according to any one of claims 32 to 36, wherein the lower portion further comprises an anode melt collecting area, and the anode structure is vertically aligned with an upper portion of the anode melt collecting area.

38. 38. The method of claim 37, wherein the cathode melt collection area is separated from the anode melt collection area by a partition disposed therebetween.

39. 8. The method of claim 6, wherein the anode structure defines an anode flow path through which the impure aluminum in molten form flows from the top to the anode melt collection area.

40. 40. A method for refining aluminium according to any one of claims 33 to 39, wherein the second anode structure portion is configured to be impregnated with the impure aluminium.

41. The method for refining aluminum according to any one of claims 33 to 40, wherein the second anode structure portion is made of a porous carbon material.

42. The aluminum refining method according to any one of claims 33 to 41, wherein the second anode structure part is made of graphite, carbon fiber cloth, porous TiB ２ and a foam.

43. The method for refining aluminium according to any one of claims 32 to 42, wherein the anode structure is made of an aluminium-wettable material.

44. 44. The aluminum refining method of claim 43, wherein the aluminum-wetting material comprises TiB2 on at least a surface of the anode structure. ２ 1. A method for refining aluminum comprising the steps of:

45. 45. The aluminum refining method according to claim 44, wherein the TiB ２ is an electroplated layer on said surface of said anode structure.

46. 32. The aluminum refining method of claim 31, wherein the anode structure is TiB ２ 13. A method of refining aluminum comprising the steps of: disposing a layer of graphite thereon.

47. The method for refining aluminum according to any one of claims 32 to 46, wherein the liquid electrolyte comprises LiF and AlF3.

48. 48. The aluminum refining method according to claim 47, wherein the liquid electrolyte further comprises NaF, KF, or CaF ２ 1. A method for refining aluminum comprising the steps of:

49. The aluminum refining method according to any one of claims 32 to 48, wherein the liquid electrolyte is about 2.7 g / cm ３ 1. A method for refining aluminum having a density of less than 1000 nm.

50. 50. The method of claim 32, further comprising: said cathode structure capturing said purified aluminum having a higher wt. % Al than said impure aluminum introduced to said anode structure.

51. 51. The method of any of claims 32-50, further comprising capturing the purified aluminum in the cathode structure at an energy consumption of about 1.5-7 kWh / kg.

52. 52. The method of claim 32, wherein the distance between the anode structure and the cathode structure is from about 2 mm to about 5 cm.

53. 53. A method for refining aluminium according to any one of claims 32 to 52, wherein the impure aluminium is not alloyed with copper before the impure aluminium is introduced into the chamber.

54. 54. A method for refining aluminium according to any one of claims 32 to 53, wherein the step of introducing impure aluminium comprises continuously introducing the impure aluminium received by the anode structure.

55. 55. A method for refining aluminium as claimed in any one of claims 32 to 54, further comprising the step of transferring the impure aluminium from the anode structure to a second cell, the transferred impure aluminium being received by the second anode structure.

56. 56. The method of claim 39, further comprising the step of transferring the impure aluminum from the anode melt collection area to the second cell, the transferred impure aluminum being received by the second anode structure.

57. 57. The method of any one of claims 55 to 56, wherein a first cell has a first cell temperature and the second cell has a second cell temperature, the second cell temperature being greater than the first cell temperature.

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