CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application Serial No. 63/318,595 filed March 10, 2022, the entire contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

Commercial aluminum electrorefining cells can be based on the three-layer Hoopes cell and can be used to make high purity aluminum. The Hoopes cell is a horizontal electrorefining cell consisting of molten electrolyte which separates 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 increase its density so that the impure aluminum and copper alloy forms the anode layer at the bottom of the cell. Additionally, an electrolyte with a density greater than the density of pure aluminum is required for Hoopes cell configurations so that the pure aluminum can form the topmost cathode layer, floating on the electrolyte, of the three-layer cell. During electrolysis, aluminum ions move from the electrolyte layer into the upper cathode layer and are replaced by aluminum ions produced in the lower anode layer, which migrate into the electrolyte layer. Although the theoretical energy costs associated with the operation of the Hoopes cell are minimal, the actual operational energy costs are significant, due mainly to the resistivity of the cell, which is a function of the distance between electrodes and the conductivity of the electrolyte. Reducing the distance between electrodes and/or increasing the conductivity of the electrolyte in a Hoopes cell can be challenging. For example, only electrolytes having the necessary density properties can be used and higher density electrolytes tend to have lower conductivity. Additionally, in Hoopes-cell based electrorefining processes, the aluminum in the anode layer at the bottom of the cell can become depleted over time, and as such, Hoopes-cell based systems can require periodic exchanges of the aluminum-depleted anode layer with new impure aluminum and copper alloy material, which can reduce system efficiency. Therefore, there is a need in the art for electrorefining systems and methods of aluminum purification that are not as energy intensive as the systems and methods associated with the Hoopes cell. Additionally, there is a need for electrorefining systems capable of continuous operation.

SUMMARY

The purpose and advantages of the disclosed subject matter will be set forth in and apparent from the description that follows, as well as will be learned by practice of the disclosed subject matter. For purpose of illustration and not limitation, the various embodiments described herein relate to systems and methods for purifying 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 from the appended drawings.

To achieve these and other advantages, and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes systems and methods of aluminum purification. Aluminum purification systems in accordance with the disclosed subject matter include a cell defining a chamber having an upper portion and a lower portion. The lower portion includes a cathode molten material collection area defined therein. Systems in accordance with the disclosed subject matter further include an anode structure disposed in the upper portion of the chamber vertically aligned above the lower portion and a cathode structure disposed in the upper portion of the chamber vertically aligned above the cathode molten material collection area. A liquid electrolyte is included within the chamber in fluid communication with the anode structure and the cathode structure. The anode structure is configured to receive impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density. Further, the cathode structure is configured to capture purified aluminum in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum through the liquid electrolyte, the cathode structure further defining a cathode flow path along which purified aluminum can flow from the upper portion to the cathode molten material collection area.

An interface can be defined between the liquid electrolyte and molten aluminum contained in the cathode molten material collection area, and the interface can be below the cathode structure. The liquid electrolyte can flow freely between the anode structure and the cathode structure.

In accordance with an aspect of the disclosed subject matter, the anode structure can include a first anode structure portion and a second anode structure portion and an anode reservoir therebetween, and the anode structure can be configured to receive 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 can include pores. For example, the pores in the second anode structure can be sized to prevent impure aluminum from flowing 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 become impregnated with impure aluminum. Additionally or alternatively, the second anode structure portion can be configured to slowly allow the impure aluminum to transit through the anode face.

The lower portion can include an anode molten material collection area.

The anode structure can be vertically aligned above the anode molten material collection area. Additionally or alternatively, the cathode molten material collection area can be separated from the anode molten material collection area by a partition disposed therebetween. An interface can be defined between the liquid electrolyte and molten aluminum contained in each of the anode molten material collection area and the cathode molten material collection area, and the partition can extend within the chamber from a bottom of the cell to a height above the interface. Additionally or alternatively, the liquid electrolyte can have an upper surface and the partition can not contact the upper surface of the liquid electrolyte.

In accordance with an aspect of the disclosed subject matter, the anode structure can define an anode flow path along which impure aluminum in a molten state can flow from the upper portion to the anode molten material collection area. For example, the anode flow path can extend from the anode reservoir through the second anode structure portion to the anode molten material collection area.

Additionally or alternatively, the anode structure can include an aluminum- wettable material. The anode flow path can include a layer of molten impure aluminum along the surface of the anode structure. The aluminum-wettable material can include titanium diboride (TiB2) at least on a surface of the anode. For example, the TiB2 can be an electroplated layer on the surface of the anode structure. Additionally, or alternatively, the anode structure can include graphite and the TiB2 layer can be disposed thereon.

In accordance with another aspect of the disclosed subject matter, the cathode structure can include an aluminum-wettable material. Additionally or alternatively, the cathode flow path can include a layer of molten purified aluminum along the surface of the cathode structure. The aluminum-wettable material can include TiB2 at least on a surface of the cathode structure. For example, the TiB2 can be an electroplated layer on the surface of the cathode structure. Additionally, or alternatively, the cathode structure can include graphite and the TiB2 layer can be disposed thereon. Additionally or alternatively, the cathode structure can include tungsten.

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 cathode structure can both include the same wettable material.

In accordance with another aspect of the disclosed subject matter, the liquid electrolyte can include lithium fluoride (LiF) and aluminum fluoride (A1F3). The liquid electrolyte can further include sodium fluoride (NaF), potassium fluoride (KF), calcium fluoride (CaF2), and other metal fluorides which will obtain an equilibrium with the refining process. The liquid electrolyte can have a density of less than about 2.7 g/cm ³ .

In accordance with an aspect of the disclosed subject matter, the distance between the anode structure and cathode structure can be between about 2mm and about 5 cm.

The disclosed subject matter further includes methods of aluminum purification. Methods in accordance with the disclosed subject matter include operating an aluminum purification system having any of the features described above. Methods in accordance with the disclosed subject matter further include introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into the chamber to be received by the anode structure. As embodied herein, the anode structure can define an anode flow path along which the impure aluminum can flow from the upper portion to the anode molten material collection area. Methods in accordance with the disclosed subject matter further include capturing purified aluminum in a molten state having a purified aluminum density greater than the electrolyte density at the cathode structure from the impure aluminum through the liquid electrolyte, the cathode structure defining a cathode flow path along which the purified aluminum can flow from the upper portion to the cathode molten material collection area and collecting in the second molten collection area purified aluminum released from the cathode structure.

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 claimed.

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. l is a schematic side cross-sectional view of an aluminum purification system in accordance with the disclosed subject matter.

FIG. 2 is an exemplary method of aluminum purification in accordance with the disclosed subject matter.

FIG. 3 is a schematic side cross-sectional view of an aluminum purification system in accordance with the disclosed subject matter.

FIG. 3 A is a schematic side cross-sectional view of an aluminum purification system in accordance with the disclosed subject matter.

FIG. 4 is a schematic partial side cross-sectional view of an aluminum purification system in accordance with the disclosed subject matter.

FIG. 5 is a schematic partial side cross-sectional view of an aluminum purification system in accordance with the disclosed subject matter. DETAILED DESCRIPTION

Reference will now be made in detail to the 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 the detailed description of the system. The accompanying drawings, where like reference numerals refer to identical or functionally similar elements throughout the separate views, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the disclosed subject matter.

The disclosed subject matter is generally directed to systems and methods for aluminum purification. Aluminum purification systems in accordance with the disclosed subject matter generally include a cell defining a chamber. The chamber includes an upper portion and a lower portion. The lower portion includes a cathode molten material collection area defined therein.

Systems in accordance with the disclosed subject matter further include an anode structure and a cathode structure disposed in the upper portion of the chamber. The anode structure is vertically aligned above the lower portion. The cathode structure is vertically aligned above the cathode molten material collection area. Systems in accordance with the disclosed subject matter further include 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.

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 purified aluminum in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum through the liquid electrolyte. The cathode structure further defines a cathode flow path along which purified aluminum can flow from the upper portion to the cathode molten material collection area.

The disclosed subject matter further includes methods of aluminum purification. Methods of aluminum purification in accordance with the disclosed subject matter generally include operating a purification 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 molten material collection area defined therein. The system further includes an anode structure and a cathode structure disposed in the upper portion of the chamber. The anode structure is vertically aligned above the lower portion. The cathode structure is vertically aligned above the cathode molten material collection area. A liquid electrolyte is within the chamber and is in fluid communication with the anode structure and the cathode structure.

Methods of aluminum purification in accordance with the disclosed subject matter further include introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into the chamber to be received by the anode structure. Methods in accordance with the disclosed subject matter further include capturing purified aluminum in a molten state having a purified aluminum density greater than the electrolyte density at the cathode structure from the impure aluminum through the liquid electrolyte, the cathode structure defining a cathode flow path along which the purified aluminum can flow from the upper portion to the cathode molten material collection area, and collecting in the cathode molten material collection area purified aluminum released from the cathode structure.

For purpose of explanation and illustration, and not limitation, exemplary systems and methods of aluminum purification in accordance with the disclosed subject matter are shown in FIGS. 1 and 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 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.” As used herein, the term “purified aluminum” is a broad and relative term and includes material having a higher wt. % aluminum than impure aluminum material.

For purpose of illustration and not limitation, reference is made to the exemplary aluminum purification system 100 of Fig. 1. In accordance with the disclosed subject matter, the purification 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 molten material collection area 106. As embodied herein, the lower portion 104 can further include an anode molten material collection area 105. Additionally or alternatively, the anode molten material collection area 105 can be separated from the cathode molten material collection area 106 by a partition 107 disposed therebetween. As embodied herein, the anode molten material collection area 105 and cathode molten material collection area 106 can define respective reservoirs separated by the partition 107, and each can be configured to receive molten material. As further embodied herein, the partition 107 can extend along a centerline of the system 100 and the anode molten material collection area 105 and cathode molten material collection area 106 can define respective reservoirs having approximately the same volume. Alternatively, the anode molten material collection area 105 and cathode molten material collection area can have different dimensions and volumes. In accordance with the disclosed subject matter, an 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 molten material collection area 105. The anode structure 108 is configured to receive impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density. For purpose of example and as embodied herein, the anode structure 108 can define an anode flow path along which impure aluminum can flow from the upper portion 103 to the anode molten material collection area 105, as described further 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 not greater than 90 degrees measured in the presence of fluoride electrolytes, although aluminum-wettable materials having a contact angle greater than 90 degrees can also be used. For purpose of example and as embodied herein, the aluminum-wettable material can include titanium diboride (TiB2). The anode structure can be made entirely of the aluminum-wettable material. Alternatively, a layer of aluminum-wettable material can be provided on the surface of the anode structure. For example and as embodied herein, the anode 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 anode structure. Additionally or alternatively, titanium diboride can be thermal sprayed onto the anode structure.

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

In accordance with the disclosed subject matter, a cathode structure 109 is disposed in the upper portion of the chamber and vertically aligned above the cathode molten material collection area 106. The cathode structure 109 defines a cathode flow path along which purified aluminum can flow from the upper portion to the cathode molten material collection area 106, as described further herein. As embodied herein, the system 100 includes one cathode structure 109; however, additional cathode structures can be included. The number of cathode structures can be selected based on the desired performance properties of the purification system. For example, cathode structures can be placed in series or in parallel, as described above. As further embodied herein, the cathode structure 109 can be disposed in the upper portion 103 of the chamber opposite to the anode structure 108 and spaced from the anode structure by an anode structure-cathode structure distance. The anode structure-cathode structure distance can be selected according to the desired properties of the system. For purpose of example, the anode structure-cathode structure distance can be between 2mm and 5 cm. As embodied herein, the anode structure-cathode structure distance can be approximately 4 cm.

As embodied herein, the cathode structure can include an aluminum- wettable material. Suitable aluminum-wettable materials for the cathode structure can include, for example, materials having a contact angle with molten aluminum of not greater than 90 degrees, although aluminum-wettable materials having a contact angle greater than 90 degrees can also be used. As embodied herein, both the anode structure and cathode structure can include a aluminum-wettable materials. As an example, the aluminum-wettable material for both the anode structure and the cathode structure can be titanium diboride (TiB2). Additionally or alternatively, the anode structure and cathode structure can have different aluminum-wettable materials. As described above, the cathode structure can be made entirely of the aluminum-wettable material. Alternatively, a layer of 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.

Both the anode structure 108 and cathode structure 109 are in fluid communication with an liquid electrolyte 110 within the chamber 102. As embodied herein, the liquid electrolyte can be disposed in the chamber 102 between the anode structure 108 and the cathode structure 109 and above the anode molten material collection area 105 and cathode molten material collection area 106. As embodied herein, the electrolyte 110 can flow freely between the anode structure 108 and the cathode structure 109. The liquid electrolyte 110 has an electrolyte density. As described further herein, impure aluminum added to the system 100 has an impure aluminum density greater than the electrolyte density. Additionally, purified aluminum captured at the cathode structure has a purified aluminum density greater than the electrolyte density. As embodied herein, the liquid electrolyte has an upper surface 111 in the upper portion of the chamber, wherein the partition 107 is configured so as not to contact the upper surface. As further embodied herein, an interface 117 can be defined between the liquid electrolyte 110 and molten aluminum contained in the cathode molten material collection area 106.

The interface 117 can be below the cathode structure 109.

The liquid electrolyte can be any suitable medium in which the flow of electrical current is carried out by the movement of ions/ionic species. For purpose 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, which will obtain an equilibrium with the refining process. For purpose of example and not limitation, the liquid electrolyte can include sodium fluoride (NaF) and aluminum fluoride (A1F3). Additionally or alternatively, and for example and not limitation, the liquid electrolyte can include lithium fluoride (LiF) and potassium fluoride (KF). As described further herein, the liquid electrolyte 110 can be selected so as to provide the desired electrolyte density and related performance characteristics. For example, the liquid electrolyte can have a density of less than about 2.7 g/cm ³ .

As embodied herein, the anode structure 108 can define an anode flow path along which impure aluminum 112 in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion 103 to the anode molten material collection area 105. The impure aluminum 112 can be heated to a molten state using any suitable means. For purpose of example and not limitation waste heat, such as from another manufacturing process, can be used to heat the impure aluminum.

As embodied here, the anode structure 108 can include a wettable material as described above, and the anode flow path can include a thin layer of molten impure aluminum along the surface of the anode structure 108. For purpose of example and as embodied herein, impure aluminum 112 can be introduced in the chamber 102 at an upper portion of the anode structure 108, and the impure aluminum 112 can flow down a surface of the anode structure 108 opposite to the cathode structure 109. As embodied herein, a thin film of impure aluminum 112 can be created along the surface of the anode structure 108 as the impure aluminum flows along the surface of the anode structure 108 from the upper portion to the lower portion. The anode structure 108 can be comprised of non- conductive materials, and the impure aluminum 112 can form the electrically conductive anode for the system. The system 100 can further include one or more leads electrically connected to the conductive anode, as is known in the art.

As embodied herein, the impure aluminum 112 can drip into the anode molten material collection area 105 when the impure aluminum 112 reaches the lower edge of the anode structure 108. Additionally or alternatively, the anode flow path can extend through the anode structure 108 or a portion thereof, as described further herein. The flow of impure aluminum 112 from the upper portion 103 to the anode molten material collection area 105 is related to, among other things, the relative density of the liquid electrolyte 110 and the impure aluminum 112. The impure aluminum 112 has a greater density than the electrolyte density and tends to flow down within the cell 101 and the liquid electrolyte 110. As described further herein, systems in accordance with the disclosed subject matter can be used to purify impure aluminum that has not been alloyed with copper to increase its density, as is common in other aluminum purification systems, such as the Hoopes cell.

As described above, the anode molten material collection area 105 can include an outlet 114 in fluid communication with the anode molten material collection area 105 for removal of impure aluminum 112 from the anode molten material collection area 105. As embodied herein, impure aluminum 112 from the anode molten material collection area 105 can be recirculated to the top of the system 100 and the anode 108, for example, to maintain a thin film of impure aluminum 112 on the anode 108. For example, and as embodied herein, the system 100 can include a pump 116 in fluid communication with the outlet 114, and the pump 116 can circulate impure aluminum 112 from the anode molten collection area 105 to the anode structure 108. Additionally, or alternatively, the outlet 114 can be used to bleed impure aluminum 112 from cell 101 and new impure aluminum material can be introduced to the cell. Additionally or alternatively, impure aluminum 112 can be transferred to another cell through the outlet 114.

In accordance with the disclosed subject matter, the cathode structure 109 is configured to capture purified aluminum 113 in a molten state having an impure aluminum density greater than the electrolyte density from the impure aluminum 112 through the liquid electrolyte 110. The cathode structure 109 further defines a cathode flow path along which purified aluminum 113 can flow from the upper portion 103 to the cathode molten material collection area 106. As described above with respect to the anode flow path, the flow of purified aluminum 113 from the upper portion 103 to the cathode molten material collection area 106 is related to, among other things, the relative density of the liquid electrolyte 110 and the purified aluminum 113. The purified aluminum 113 has a greater density than the electrolyte density and tends to flow down within the cell 101 and the liquid electrolyte 110. As described further herein, systems in accordance with the disclosed subject matter can purify aluminum at higher efficiencies than other systems, such as Hoopes cells, which require liquid electrolyte with a density greater than that of purified aluminum. For example, systems in accordance with the disclosed subject matter can be used with electrolytes having higher conductivity and lower density.

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

The cathode structure 109 can be comprised of non-conductive material, and the purified aluminum 113 can form the electrically conductive cathode for the system 100. The system 100 can further include one or more leads electrically connected to the conductive cathode, as is 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 move to the cathode structure through the liquid electrolyte 110. As embodied herein, the aluminum ions can form a thin film of purified aluminum 113 on the surface of the cathode structure 109.

The cathode structure 109 can be configured to capture purified aluminum having a higher weight percent (wt. %) aluminum than the impure aluminum introduced to the anode structure. For purpose of example and not limitation, impure aluminum having at least 80 wt. % aluminum can be introduced to the anode structure, and the purified aluminum captured at the cathode structure can have at least 99 wt. % aluminum. Additionally or alternatively, the purified aluminum captured at the cathode structure can have at least 99.5 wt. % aluminum. Additionally or alternatively, the purified aluminum captured at the cathode structure can have at least 99.9 wt. % aluminum.

The system 100 can include an outlet 115 in fluid communication with the cathode molten material collection area 106. For example and as embodied herein, outlet 115 can be in fluid communication with the cathode molten material collection area 106 for removal of purified aluminum 113 therefrom.

FIG. 3 depicts another purification system 300 in accordance with the disclosed subject matter. In accordance with the disclosed subject matter, the purification system 300 comprises a cell 301 defining a chamber 302. The chamber 302 has an upper portion 303 and a lower portion 304. The lower portion includes a cathode molten material collection area 306. As embodied herein, the lower portion 304 can further include an anode molten material collection area 305. The anode molten material collection area 305 can be separated from the cathode molten material collection area 306 by a partition 307 disposed therebetween.

The system further includes an anode structure 308 disposed in the upper portion of the chamber 302 and vertically aligned above the lower portion 304. As embodied herein, the anode structure can be vertically aligned above the anode molten material collection area 305. A cathode structure 309 is disposed in the upper portion of the chamber 302 and vertically aligned above the cathode molten material 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.

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 liquid electrolyte 310. As embodied herein, the anode structure 308 can define an anode flow path along which impure aluminum 312 in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion 303 to the anode molten material collection area 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 molten material collection area 305. For example, and as described further herein, the second anode structure portion 322 can be porous, and impure aluminum 312 can flow from the anode reservoir 323 through the pores of the second anode structure portion 322 and fall into the anode molten material collection area 305.

For purpose of example, and as embodied herein, a wall of the cell 301 can define the first anode structure portion 321 and the second anode structure portion 322 can form a barrier to retain the impure aluminum 312 between the first anode structure portion 321 and the second anode structure portion 322. As described above, systems can incorporate multiple cells, and a wall of the cell can, for example, define a first anode structure portion for a first cell and define a cathode structure for a second, adjacent, cell. The second anode structure portion can be positioned relative to the first anode structure portion 321 to achieve the desired thickness and volume of impure aluminum 312 within the anode reservoir 323. As embodied herein, the anode reservoir 323 can be filed with impure aluminum 312. For example, and as embodied herein, the anode reservoir 323 can be filed with only impure aluminum and have no liquid electrolyte therein.

The second anode structure portion 322 can comprise any suitable material. For purpose of example and not limitation, and as embodied herein, the second anode structure portion 322 can comprise a porous material. For example, the second anode structure portion 322 can include graphite, carbon fiber cloth, porous TiB2 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 pathways can be defined in the second anode material 322.

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 molten material collection area 305. For example, and as embodied herein, the second anode structure portion 322 can become impregnated with the 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 move to the cathode structure through the liquid electrolyte 110.

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

As further embodied herein, the anode structure 308 can include a anode reservoir bottom portion 325. For purpose of example and as 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 comprise a nonporous material. Additionally or alternatively, and as further embodied herein, the anode reservoir bottom portion can separate and electrically insulate the anode from the anode molten material collection area 305.

As embodied herein, the impure aluminum 312 can be the anode in the system 300. For example, the first anode structure portion 321 and second anode structure portion 322 can be comprised of non-conductive materials, or materials with lower conductance than the impure aluminum 312. Additionally or alternatively, a lead can be used in communication with the impure aluminum 312 to apply a voltage and/or current thereto.

As described above, the liquid electrolyte 310 has an electrolyte density and the impure aluminum 312 has an impure aluminum density greater than the electrolyte density. The flow of impure aluminum 112 from the upper portion 303 to the anode molten material collection area 305 is related to, among other things, the relative density of the liquid electrolyte 310 and the impure aluminum 312. As described further herein, purified aluminum 313 captured at the cathode structure 309 has a purified aluminum density greater than the electrolyte density. As a result of the relative densities of the liquid electrolyte 310, impure aluminum in the anode molten material collection area 305, and purified aluminum in the cathode molten material collection area 306, the liquid electrolyte 310 can form a layer within the chamber 302 above the molten aluminum contained in the anode molten material collection area 305 and cathode molten material 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 molten material collection area 305 and cathode molten material collection area 306, respectively. As further embodied herein, the partition 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 in the anode molten material collection area 305 and the purified aluminum contained in the cathode molten material collection area 306. As further embodied herein, the interface 316 can be below the cathode structure 309.

As embodied herein, the area of the chamber 302 between the anode structure 308 and the cathode structure 309 can be free of barriers or membranes or other structures which could otherwise impede the flow of electrolyte 310 between the anode structure 310, 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 steady state kinetics of the system 300.

The cathode structure 309 is configured to capture purified aluminum 313 in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum 312 through the liquid electrolyte 310. The cathode structure 309 further defines a cathode flow path along which the purified aluminum 313 can flow from the upper portion 303 to the cathode molten material collection area 306. As described above, cathode structure 309 is disposed in the upper portion of the chamber 302 and is vertically aligned above the cathode molten material collection area 306. The cathode structure 309 is configured to capture purified aluminum 313 in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum through the liquid electrolyte 310.

The cathode structure 309 can be comprised of any suitable material. For purpose of example and not limitation the material of the cathode structure can include tungsten or graphite. Additionally or alternatively, and as embodied herein, the cathode structure 309 can be comprised of aluminum. The cathode structure 309 can have any suitable shape and structure. For purpose of example, and as embodied herein, the surface of the cathode structure 309 can include one or more grooves defined therein and purified aluminum 313 can be deposited in the grooves of the cathode structure 309. For example, the cathode structure 309 can include grooves defined in the surface of the cathode structure and extending vertically. Including grooves or channels in the cathode structure can provide further stability to the layers of aluminum that form on the cathode structure during operation of the system. Additionally or alternatively, including grooves or channels in the anode the cathode structure can reduce the likelihood of aluminum bridging between the anode and cathode. For example and not limitation, including 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 structure and cathode structure is reduced, as described further herein. As described above, 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 molten material collection area 306.

FIG. 3A depicts another purification system 300a in accordance with the disclosed subject matter. In accordance with the disclosed subject matter, the purification system 300a comprises a cell 301a defining a chamber 302a. The chamber 302a has an upper portion 303a and a lower portion 304a. The lower portion 304a includes a cathode molten material collection area 306a defined therein.

The system further includes an anode structure 308a disposed in the upper portion 303 a of the chamber 302a and vertically aligned above the lower portion 304a. A cathode structure 309a is disposed in the upper portion 303a of the chamber 302a and vertically aligned above the cathode molten material 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.

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 purified aluminum 313a in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum through the liquid electrolyte 310a. The cathode structure 309a further defines a cathode flow path along which purified aluminum 313a can flow from the upper portion 303a to the cathode molten material collection area 306a. As embodied here, the cathode flow path can include a layer of molten purified aluminum 313a along the surface of the cathode structure 309a. As embodied herein, the purified aluminum 313a collected on the cathode structure 309a can flow along the vertically oriented cathode structure 309a and drip into the cathode molten material collection area 306a.

As embodied herein, the anode structure 308a can include a first anode structure portion 321a and a second anode structure portion 322a and 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 liquid electrolyte 310a. As embodied herein, the second anode structure portion 322a can be porous. For example and as embodied herein, the pores in 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.

For purpose of example, and as embodied herein, a wall of the cell 301a can define the first anode structure portion 321a and the second anode structure portion 322a can form a barrier to retain the impure aluminum 312a between the first anode structure portion 321a and the second anode structure portion 322a. As described above, systems can incorporate multiple cells, and a wall of the cell can, for example, define a first anode structure portion for a first cell and define a cathode structure for a second, adjacent, cell. The second anode structure portion can be positioned relative to the first anode structure portion 321a to achieve the desired thickness and volume of impure aluminum 312a within the anode reservoir 323a. As embodied herein, the anode reservoir 323a can be filed with impure aluminum 312a. For example, and as embodied herein, the anode reservoir 323a can be filed with only impure aluminum and have no liquid electrolyte therein.

The second anode structure portion 322a can comprise any suitable material. For purpose of example and not limitation, and as embodied herein, the second anode structure portion 322a can comprise a porous material.

As further embodied herein, the anode structure 308a can include an anode reservoir bottom portion 325a. For purpose of example and as 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 comprise a nonporous material. Additionally or alternatively, and as further embodied herein, the anode reservoir bottom portion 325a can separate and electrically insulate the anode structure 308a from the cathode molten material collection area 306a.

As embodied herein, system 300a can include a pump 316a. Pump 316a can be used to remove impure aluminum material 312a from the reservoir 323a. For purpose of example and not limitation, transferring impure aluminum 312a from the anode structure 308a can prevent build up and/or concentration of impurities in the impure aluminum 312a received at the anode structure, as described further herein. For example, impure aluminum 312a can be transferred from the anode structure 308a to a second cell, the transferred impure aluminum to be received by a second anode structure, as described further herein.

In accordance with an aspect of the disclosed subject matter, and as embodied herein, aluminum purification systems can include more than one cell. For purpose of example and illustration reference is made to the exemplary system 400 depicted in FIG. 4. In accordance with the disclosed subject matter, the purification 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 molten material collection area 406a. As embodied herein, the lower portion 404 can further include an anode molten material collection area 405. The anode molten material collection area 405 can be separated from the cathode molten material collection area 406a by a partition 407a disposed therebetween. The system 400 further includes an anode structure 408 disposed in the upper portion of the chamber 402a and vertically aligned above the lower portion 404. As embodied herein, the anode structure 408 can be disposed in the upper portion of the chamber 402a and vertically aligned above the anode molten material collection area 405. A cathode structure 409a is disposed in the upper portion of the chamber 402a and vertically aligned above the cathode molten material 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 purified aluminum 413 in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum 412 through the liquid electrolyte 410. The cathode structure 409a further defines a cathode flow path along which the purified aluminum 413 can flow from the upper portion 403 to the cathode molten material collection area 406a. As embodied herein, the anode structure 408 can define an anode flow path along which impure aluminum 412 in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion to the anode molten material collection area 405.

For purpose of example and 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 molten material collection area 406b. As embodied herein, the lower portion 404 can further include an anode molten material collection area 405. The anode molten material collection area 405 can be separated from the cathode molten material collection area 406b by a partition 407b disposed therebetween. The system 400 further includes an anode structure 408 disposed in 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 in the upper portion of the chamber 402b and vertically aligned above the anode molten material collection area

405. A cathode structure 409b is disposed in the upper portion of the chamber 402b and vertically aligned above the cathode molten material collection area 406b. A 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 purified aluminum 413 in a molten state having a purified aluminum density greater than the electrolyte density from the impure aluminum 412 through the liquid electrolyte 410. The cathode structure 409b further defines a cathode flow path along which the purified aluminum 413 can flow from the upper portion 403 to the cathode molten material collection area 406b. As embodied herein, the anode structure 408 defines an anode flow path along which impure aluminum 412 in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion to the anode molten material collection area 405.

For purpose of example, chambers 402a and 402b can include separate anode structures. Additionally or alternatively, and as embodied herein, anode structure 408 can be a common anode structure for chambers 402a and 402b and for cathode structures 409a and 409b. For purpose of example and as embodied herein, the anode structure 408 can include a first anode structure portion 421 and a second anode structure portion 422 and an anode reservoir 423 therebetween. The anode structure 408 can be configured to receive the impure aluminum 412 in the anode reservoir 423. As embodied herein, the anode flow path can extend from the anode reservoir 423 through both the first anode structure portion 421 and the second anode structure portion 422 to the anode molten material collection area 405. For example and as embodied herein, the first anode structure portion 421 and the second anode structure portion 422 can comprise porous material and the impure aluminum 412 can flow therethrough.

As further embodied herein, the anode structure 408 can include a anode reservoir bottom portion 425. For purpose 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 portion 425 can comprise a nonporous material. Additionally or alternatively, and as further embodied herein, the anode reservoir bottom portion can separate and electrically insulate the first anode structure portion 421 and the second anode structure portion 422 from the anode molten material collection area 405.

The inclusion of multiple chambers in system 400 can provide advantages, such as for example, redundancy. For example, if chamber 402a and/or cathode 409a requires maintenance, purification can continue in chamber 402b. Additionally or alternatively, both chambers 402a and 402b can operate simultaneously, which can increase the rate of aluminum purification of the system. It is to be understood that system 400 can include more than two chambers and/or anode structure/cathode structure pairs. Additionally or alternatively, and as described above chambers and/or anode structure/cathode structure pairs can be operated in series to achieve desired aluminum purification. For example and not limitation, 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 within the system and subject to further purification, as described further herein. Additionally or alternatively, impure aluminum from the anode structure can be transferred to another cell for further purification. For example, impure aluminum can be transferred from the anode structure of a first cell to the anode structure of a second cell. For purpose of example and not limitation, impure aluminum can be transferred from anode reservoir. Additionally or alternatively, impure aluminum can be transferred from anode molten material collection area. Impure aluminum can be transferred from the anode structure of the first cell to the anode structure of a second cell using standard metal transfer methods. For example and not limitation, impure aluminum can be syphoned periodically from the anode structure using standard metal transfer methods. Additionally or alternatively, impure aluminum can be allowed to steadily drain from the anode structure into a collection trough and/or sump for removal, such as to another anode structure. Transferring impure aluminum from the anode structure can prevent build up and/or concentration of impurities in the impure aluminum received at the anode structure.

Aluminum purification cells can be operated in series at different temperatures. For example and as embodied herein, the aluminum purification cell temperature can be selected based on the concentration of aluminum in the impure aluminum to be introduced into the cell. For purpose of example and not limitation, a first cell can have a first cell temperature, a 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 limitation, cell temperature can be between temperatures of about 640°C to about 900°C depending on the concentration of aluminum in the impure aluminum to be introduced into the cell. Cell temperature as used herein refers to the temperature of liquid electrolyte in the cell. Higher aluminum purification cell temperatures can be beneficial for purifying impure aluminum having a lower concentration of aluminum, (i.e., having a higher concentration of impurities). For example, higher temperatures can be used to keep the impure aluminum liquid when the impure aluminum has a lower concentration of aluminum. As embodied herein, impure aluminum having a first concentration of aluminum can be introduced to a first cell and received by the anode structure of the first cell. As aluminum is extracted from the impure aluminum at the anode structure and captured at the cathode structure of the first cell, the concentration of aluminum in the impure aluminum at the anode structure of the first cell can decrease 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 a second cell where the impure aluminum can be received by a second anode structure. 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.

For purpose of illustration and not limitation, reference is made to the exemplary aluminum purification system 500 depicted in FIG. 5. In accordance with the disclosed subject matter, the purification 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 molten material collection area 506a. As embodied herein, the lower portion 504 can further include an anode molten material collection area 505a. The anode molten material collection area 505a can be separated from the cathode molten material collection area 506a by a partition 507a disposed therebetween. The system 500 further includes an anode structure 508a disposed in the upper portion of the chamber 502a and vertically aligned above the lower portion 504. As embodied herein, the anode structure 508a can be disposed in the upper portion of the chamber 502a and vertically aligned above the anode molten material collection area 505a. A cathode structure 509a is disposed in the upper portion of the chamber 502a and vertically aligned above the cathode molten material 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.

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 and an anode reservoir 523a therebetween. The anode structure 508a can receive impure aluminum 512a in the anode reservoir 523a. As embodied herein, the anode structure 508a can define an anode flow path along which impure aluminum 512a in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion 503 to the anode molten material 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 molten material collection area 505a.

The cathode structure 509a is configured to capture purified aluminum 513a in a molten state having a purified aluminum 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 along which the purified aluminum 513a can flow from the upper portion 503 to the cathode molten material collection area 506a.

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

As embodied herein 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 molten material collection area 506b. As embodied herein, the lower portion 504 can further include an anode molten material collection area 505b. The anode molten material collection area 505b can be separated from the cathode molten material collection area 506b by a partition 507b disposed therebetween. The system 500 further includes a second anode structure 508b disposed in the upper portion of the second chamber 502b and vertically aligned above the lower portion 504. As embodied herein, the second anode structure 508b can be disposed in the upper portion of the chamber 502a and vertically aligned above the anode molten material collection area 505b. A cathode structure 509b is disposed in the upper portion of the chamber 502b and vertically aligned above the cathode molten material 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.

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 the second, lower, concentration of aluminum from the anode structure 508a of the first cell. Aluminum can be transferred from the first anode structure 508a to the second anode structure 508b using any suitable method. For purpose of example and as embodied herein, a pump 516 can transfer aluminum from the first anode structure 508a to the second anode structure 508b as denoted 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 and an anode reservoir 523b therebetween. The anode structure 508b can receive impure aluminum 512b in the anode reservoir 523b. As embodied herein, the anode structure 508b can define an anode flow path along which impure aluminum 512b in a molten state having an impure aluminum density greater than the electrolyte density can flow from the upper portion 503 to the anode molten material 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 molten material collection area 505b.

The cathode structure 509b is configured to capture purified aluminum 513b in a molten state having a purified 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 along which the purified aluminum 513b can flow from the upper portion 503 to the cathode molten material collection area 506b.

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, and as described above, the impure aluminum 512b received at the second anode structure 508b can have a lower concentration of aluminum as compared to the impure aluminum 512a received at the first anode structure 508a. The cell temperature can be selected based on the concentration of impure aluminum to be purified, as described above.

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

The temperature of aluminum purification cells can be controlled using any suitable method. For purpose of example and not limitation, walls of the aluminum purification cell can include heat transfer systems to control the temperature of the aluminum purification cell. For example and not limitation, walls of the aluminum purification cell can include two plates with an interstitial space defined therebetween. The plates of the cell wall can include, for example, steel or high temperature alloy. Additionally or alternatively, the plates of the cell wall can include a graphite layer facing the interstitial space. Additionally or alternatively, coiled tubes can be included in the interstitial space. For example, tubes can be coiled in a sinusoidal pattern within the interstitial space. The remainder of the interstitial space can be filled with conductive material, such as for example, graphite powder. Air or other gas can be flowed through the tubes to control the temperature of the cell. For example, heated air or other gas can be flowed through the tubes to raise the temperature of the cell and cooled air can be flowed through the tubes to lower the temperature of the cell. As embodied herein, the aluminum purification cell can be heated to desired temperature for cell startup. Additionally or alternatively, the aluminum purification cell can be cooled to maintain desired operating temperatures during steady-state operation of the aluminum purification cell.

The disclosed subject matter further includes methods for purifying aluminum. Methods in accordance with the disclosed subject matter include operating an aluminum purification system having any of the features described above. Methods in accordance with the disclosed subject matter further include introducing impure aluminum in a molten state having an impure aluminum density greater than the electrolyte density into the chamber to be received by the anode structure, the anode structure defining an anode flow path along which the impure aluminum can flow from the upper portion to the anode molten material collection area. Methods further include capturing purified aluminum in a molten state having a purified aluminum density greater than the electrolyte density at the cathode structure from the impure aluminum through the liquid electrolyte, the cathode structure defining a cathode flow path along which the purified aluminum can flow from the upper portion to the cathode molten material collection area. Further, methods include collecting in the cathode molten material collection area purified aluminum released from the cathode structure.

For purpose of illustration and not limitation, reference is made to the exemplary method of aluminum purification of Fig. 2. In accordance with the disclosed subject matter, method 200 includes step 201 of operating an aluminum purification system. For purpose of example, and as embodied herein, the aluminum purification system can include exemplary system 100 of aluminum purification, as shown in Fig. 1. Methods in accordance with the disclosed subject matter can be used with systems having any of the features described herein. The method further includes step 202 in which impure aluminum 112 in a molten state and having an impure aluminum density greater than the electrolyte density is introduced into the chamber 102 and received by the anode structure 108. Purified aluminum 113 is captured at the cathode structure 109 from the impure aluminum 112 through the liquid electrolyte 110, as shown in step 203. As embodied herein, a voltage and/or current can be applied across the impure aluminum 112 at the anode structure 108 and the purified aluminum 113 at the cathode structure 109, and aluminum ions can flow from the anode structure 108 to the cathode structure 109 through the liquid electrolyte 110. At step 204, purified aluminum 113 is released from the cathode structure 109 and collected in the cathode molten collection area 106.

As described above, the system 100 can inlcude an anode molten material collection area 105 disposed underneath the anode structure 108. As embodied herein, methods can further include removing impure molten aluminum 112 from the anode molten material collection area 105 through outlet 114 in fluid communication with the first molten material collection area 105. As described above, the removed impure molten aluminum 112 can be reintroduced into the chamber 102 and the anode structure 108, such as by using pump 116. Additionally, or alternatively, and as described above, the system 100 can include more than one anode structure and introducing impure molten aluminum 112 into the chamber 102 can further include introducing the impure molten aluminum 112 to a second anode structure. As embodied herein, the system 100 includes one anode structure 108; however, additional anode structures can be included. The number of cells and anode structures can be selected based on the desired performance properties of the purification system. In accordance with the disclosed subject matter, a cathode structure 109 is disposed in the upper portion of the chamber such that it is vertically aligned above the cathode molten material collection area 106. As embodied herein, the system 100 includes one cathode structure 109; however, additional cathode structures can be included. The number of cells and cathode structures can be selected based on the desired performance properties of the purification system.

As described above, the cathode structure 109 defines a cathode flow path along which purified aluminum can flow from the upper portion 103 to the cathode molten material collection area 106. For example, and as embodied herein, purified aluminum can flow down the cathode structure 109 and drip into the cathode molten material collection area 106. As embodied herein, the purified aluminum 113 can be removed from the cathode molten material collection area 106 through outlet 115 in fluid communication with the second molten material collection area 106.

Systems and methods in accordance with the disclosed subject matter can be used to collect purified aluminum of high quality. For purpose of example, systems in accordance with 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. % of aluminum. As embodied herein, the purified aluminum can have 99.99 wt. % aluminum.

Additionally, systems and methods in accordance with the disclosed subject matter can be used to efficiently purify aluminum. The energy consumption of an aluminum purification system can be expressed in kilowatt hours/kilogram of aluminum produced (kWh/kg). For purpose of example, systems in accordance with the disclosed subject matter can produce purified aluminum at an energy consumption of from about 1.5 to 7 kWh/kg of purified aluminum captured at the cathode structure. Systems in accordance with the disclosed subject matter can provide improved efficiency. For example, systems in accordance with the disclosed subject matter can include more conductive electrolyte and a smaller distance between the anode structure and cathode structure, which can improve system efficiency. For example, liquid electrolytes having electrolyte density less than the density of purified aluminum can be more conductive than, for example, liquid electrolytes having electrolyte density greater than the density of purified aluminum, such as liquid electrolytes used in Hoopes cell configurations. Example 1:

About 540 g of impure Al was processed on a system having a configuration similar to the configuration of exemplary system 400 depicted in FIG. 4. In the test system the anode reservoir bottom portion 435 extended all the way to the bottom of the chamber to divide the anode molten material collection area 405 into two separate collection areas, one for each of chamber 402a and chamber 402b, respectively. The system included an anode structure having a porous second anode structure portion. The second anode structure portion comprised a graphite felt. Additionally, the liquid electrolyte used was 66% LiF and 34% NasAlFe. The liquid electrolyte had a density of about 2.1 g/cm ³ . The system included an anode-cathode distance of about 4 cm. A Tungsten cathode structure was used on a first side of the anode structure for the first chamber, and a graphite cathode structure was used on a second side of the anode structure for the second chamber. Both chambers were operated cell temperatures of about 700°C. Impure aluminum was added to the system and received at the anode structure. The impure aluminum was about 95.3% Al. Purified aluminum was collected at the molten material collection area. The purified aluminum collected at the molten material collection area included fewer impurities as compared to the impure aluminum received at the anode structure of the exemplary system. As embodied herein, the impurity reduction was as follows: Cu greater than about 97% reduction, Fe about 93% reduction, Mn about 98% reduction, Si about 96% reduction, Zn greater than about 96% reduction.

Additionally, systems and methods in accordance with the disclosed subject matter can be used without the need to modify the density of the impure aluminum feed material. For example, in a Hoopes cell configuration, impure aluminum feed material is frequently alloyed with another material, such as copper, to increase the density of the impure aluminum feed material. Alloying the impure aluminum can be required in Hoopes cell configurations, which rely on a liquid electrolyte having a density less than the impure aluminum feed material, and greater than the density of purified aluminum. Systems and methods in accordance with the disclosed subject matter include liquid electrolyte having a density less than the impure aluminum feed material and less than purified aluminum, which can alleviate the need to alloy the impure aluminum feed material or otherwise alter its density prior to introduction to the purification system.

Additionally, systems and methods in accordance with the disclosed subject matter can be configured for continuous operation. Systems and methods for continuous operation can provide advantages over other systems, such as the Hoopes cell, which can require batch processing and associated interruptions in aluminum purification. For example, during operation of systems based on the Hoopes cell configuration, the aluminum in the anode layer at the bottom of the refining cell can become depleted over time and can require periodic exchanges of the aluminum-depleted anode layer with new impure aluminum and copper alloy material. Exchanging the depleted aluminum anode layer can require pauses in aluminum purification and can reduce overall system efficiency.

The periodic exchanges and/or batch operation of Hoopes cell-based systems can be avoided using systems and methods in accordance with the disclosed subject matter. For example and as embodied herein, the anode structure can be configured to continuously receive impure aluminum in a molten state such that impure aluminum can continuously flow along the anode flow path from the upper portion to the anode molten material collection area. As embodied herein, as impure aluminum can be continuously introduced and flown along the anode flow path, exchanging depleted input material with new impure aluminum input material can be avoided. As further embodied herein, the cathode structure can be configured to continuously capture purified aluminum in a molten state. By avoiding periodic exchanges and/or batch operation, overall system efficiency can be increased.

It is to be understood that the term “impure aluminum” as used herein can encompass a wide variety of feed materials which contain aluminum as well as other materials. For purpose of example, impure aluminum feed materials can include aluminum, magnesium, lithium, and other metal materials. Systems and methods have been described herein for capturing purified aluminum from impure aluminum feed materials. In addition to capturing purified aluminum from impure aluminum feed material, it can be desirable to capture additional purified metals present in the feed material (e.g., capture purified magnesium or lithium). In this regard, additional materials of interest can be captured and separated from the impure aluminum feed material using additional processing, which can occur, for example, before or after introducing the impure aluminum material into systems and methods described herein for capturing purified aluminum. Such additional processing can be performed, for example, using chambers disclosed herein for capturing purified aluminum or similar.

In addition to the specific embodiments claimed below, the disclosed subject matter is also directed to other embodiments having any other possible combination of the dependent features claimed below and those disclosed above. As such, the particular 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 the disclosed subject matter should be recognized as 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 those embodiments disclosed.

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 include modifications and variations that are within the scope of the appended claims and their equivalents.