SYSTEMS AND METHODS OF PROTECTING ELECTROLYSIS CELLS

Abstract

Broadly, the present disclosure relates to sidewall features (e.g. inner sidewall or hot face) of an electrolysis cell, which protect the sidewall from the electrolytic bath while the cell is in operation (e.g. producing metal in the electrolytic cell).

Claims

1. An electrolysis cell, comprising: an anode; a cathode in spaced relation from the anode; a molten electrolyte bath in liquid communication with the anode and the cathode; a cell body comprising a sidewall and a bottom, wherein the cell body is configured to retain the molten electrolyte bath; wherein the sidewall comprises: a polarized sidewall portion, wherein the polarized sidewall portion is in liquid communication with the molten electrolyte bath.

2. The apparatus of claim 1, wherein the polarized sidewall portion is one of: an anodically polarized sidewall, a cathodically polarized sidewall, and combinations thereof.

3. The apparatus of claim 2, wherein the polarized sidewall portion comprises: a cathodically polarized sidewall, wherein the cathodically polarized sidewall is positioned below the bath-vapor interface and adjacent to the bottom of the cell body such that the cathodically polarized sidewall is in liquid communication with the bottom of the cell.

4. The apparatus of claim 1, wherein the polarized sidewall portion comprises: at least 50% of surface of the inner sidewall.

5. The apparatus of claim 1, further comprising: a non-polarized sidewall portion, wherein both the polarized sidewall portion and the non-polarized sidewall portion are adjacent to each other and in liquid communication with the molten electrolyte bath.

6. The apparatus of claim 5, wherein the non-polarized sidewall portion is positioned above the cathodically polarized sidewall and is in communication with the bath-air interface.

7. The apparatus of claim 5, wherein the non-polarized sidewall portion is selected from the group consisting of: a thermal conductor; a stable material; a frozen ledge device, and combinations thereof.

8. The apparatus of claim 7, wherein when the non-polarized sidewall portion comprises the thermal conductor, wherein the thermal conductor is adjacent to the polarized sidewall portion and in liquid communication with at least one of: (a) a metal pad and (b) a cell bottom, wherein the thermal conductor is configured to accept heat from the molten electrolyte bath adjacent to a thermal conductor contact point, wherein, via the thermal conductor, a frozen ledge is formed between the thermal conductor and molten electrolyte bath along the portion of the sidewall where the thermal conductor contacts the molten electrolyte.

9. The apparatus of claim 7, wherein the non-polarized sidewall is configured to extend from the cell bottom to a height above a metal-to-bath interface, further wherein the non-polarized sidewall portion is configured adjacent to and in communication with the anodically polarized sidewall.

10. The apparatus of claim 7, wherein the non-polarized sidewall portion is configured to extend out from the sidewall and provide a stepped configuration, wherein the non-polarized sidewall portion comprises a stable material.

11. The apparatus of claim 2, wherein the polarized sidewall portion comprises: an anodically polarized sidewall, wherein the anodically polarized sidewall is positioned above the bottom of the cell body and adjacent to the bath-vapor interface, such that the anodically polarized sidewall is in communication with the bath-vapor interface.

12. The apparatus of claim 1, wherein the cell is further comprises a feeder configured to provide a feed material into the bath, where the feeder is retained along at least a portion of the sidewall.

13. The apparatus of claim 7, wherein the non-polarized sidewall comprises the frozen ledge device, wherein the frozen ledge device is configured to attach to the sidewall and extract heat from the molten salt bath adjacent to the frozen ledge device to define a frozen ledge along a portion of the sidewall adjacent to the frozen ledge device.

14. An electrolysis cell sidewall, comprising: a cell body having a bottom and at least one sidewall, wherein the cell body is configured to retain a molten electrolyte bath, wherein the sidewall comprises: a first sidewall portion, configured to fit onto a thermal insulation package of the sidewall and retain the electrolyte, the first sidewall portion comprising an anodically polarized sidewall portion; and a second sidewall portion configured to extend up from the bottom of the cell body, wherein the second sidewall portion is longitudinally spaced from the first sidewall portion, such that the first sidewall portion, the second sidewall portion, and a base between the first portion and the second sidewall portion define a trough; wherein the trough is configured to receive a protecting deposit and retain the protecting deposit separate from the cell bottom.

15. The system of claim 14, wherein the second sidewall portion comprises a cathodically polarized sidewall.

16. The system of claim 14, wherein the second sidewall portion comprises a non-polarized sidewall including a stable material, wherein the stable material which includes a component of the bath chemistry further wherein, via the bath chemistry and percent saturation of the non-reactive material in the bath, the sidewall is substantially non-reactive in the molten salt electrolyte.

17. The system of claim 14, further comprising a directing member, wherein the directing member is positioned between the anodically polarized sidewall and the second sidewall portion, further wherein the directing member is laterally spaced above the base of the trough, such that the directing member is configured to direct a feed material into the trough, to be retained therein as protecting deposit in the trough.

18. The system of claim 17, wherein the directing member comprises: an anodically polarized material; a stable material; a cathodically polarized material; and combinations thereof.

19. The system of claim 14, wherein the lateral spacing is not greater than 6 inches.

20. An electrolysis cell sidewall is provided, comprising: a cell body having a bottom and at least one sidewall, wherein the cell body is configured to retain the molten electrolyte bath, wherein the sidewall comprises: a first sidewall portion, configured to fit onto a thermal insulation package of the sidewall and retain the electrolyte, the first sidewall portion comprising a non-polarized sidewall portion; and a second sidewall portion comprising a cathodically polarized sidewall, the second sidewall portion configured to extend up from the bottom of the cell body, wherein the second sidewall portion is longitudinally spaced from the first sidewall portion, wherein the first sidewall portion, the second sidewall portion, and a base between the first portion and the second portion define a trough; wherein the trough is configured to receive a protecting deposit and retain the protecting deposit separately from the cell bottom.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0108] FIG. 1 depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall in accordance with the instant disclosure.

[0109] FIG. 2 depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (thermal conductor with frozen ledge) in accordance with the instant disclosure.

[0110] FIG. 3A depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (stable sidewall/non-reactive material) in accordance with the instant disclosure.

[0111] FIG. 3B depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (stable sidewall in a stepped/extended configuration) in accordance with the instant disclosure.

[0112] FIG. 3C depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (stable sidewall in a stepped/extended configuration) having a feeder providing a protecting deposit to the non-polarized sidewall, in accordance with the instant disclosure.

[0113] FIG. 3D depicts another embodiment of a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (stable sidewall in a stepped/extended configuration) having a feeder providing a protecting deposit to the non-polarized sidewall, in accordance with the instant disclosure.

[0114] FIG. 3E depicts a partial cut-away side view of a cell body having an anodic sidewall and second sidewall portion including a non-polarized sidewall (stable sidewall in a stepped/extended configuration).

[0115] FIG. 3F depicts another embodiment of a partial cut-away side view of a cell body having an anodic sidewall and second sidewall portion including a non-polarized sidewall (stable sidewall in a stepped/extended configuration).

[0116] FIG. 4 depicts a partial cut-away side view of a cell body having an anodic sidewall and a non-polarized sidewall (frozen ledge device with a frozen ledge) in accordance with the instant disclosure.

[0117] FIG. 5 depicts a partial cut-away side view of a cell body having an anodic sidewall and a second sidewall portion which is a non-polarized sidewall (stable material), including a feeder providing a protecting deposit, in accordance with the instant disclosure.

[0118] FIG. 6 depicts a partial cut-away side view of a cell body having an anodic sidewall and a second sidewall portion which is a non-polarized sidewall (stable material), including a feeder providing a protecting deposit and a directing member, in accordance with the instant disclosure.

[0119] FIG. 7 depicts a partial cut-away side view of a cell body having an anodic sidewall and a second sidewall portion which is a non-polarized sidewall (stable material), including a thermal conductor material which provides a frozen ledge between the first sidewall portion and the second sidewall portion, in accordance with the instant disclosure.

[0120] FIG. 8 depicts a partial cut-away side view of a cell body having an anodic sidewall and a second sidewall portion which is a non-polarized sidewall (stable material), including a frozen ledge device which provides a frozen ledge between the first sidewall portion and the second sidewall portion, in accordance with the instant disclosure.

[0121] FIG. 9 depicts a partial cut-away side view of a cell body having a cathodic sidewall and a non-polarized sidewall in accordance with the instant disclosure.

[0122] FIG. 10A depicts a partial cut-away side view of a cell body having a cathodic sidewall and a non-polarized sidewall (stable sidewall/non-reactive material) in accordance with the instant disclosure.

[0123] FIG. 10B depicts another embodiment of a partial cut-away side view of a cell body having a cathodic sidewall and a non-polarized sidewall, in accordance with the instant disclosure.

[0124] FIG. 10C depicts another embodiment of a partial cut-away side view of a cell body having a first sidewall portion which is a non-polarized sidewall (stable sidewall) and a second sidewall portion which is a cathodic sidewall, in accordance with the instant disclosure.

[0125] FIG. 10D depicts another embodiment of a partial cut-away side view of a cell body having a first sidewall portion which is a non-polarized sidewall (stable sidewall) and a second sidewall portion which is a cathodic sidewall, including a feeder which provides a protecting deposit, in accordance with the instant disclosure.

[0126] FIG. 11 depicts a partial cut-away side view of a cell body having a cathodic sidewall and a non-polarized sidewall (frozen ledge device with a frozen ledge in accordance with the instant disclosure.

[0127] FIG. 12 depicts a partial cut-away side view of a cell body having a cathodic sidewall and a non-polarized sidewall (thermal conductor with a frozen ledge) in accordance with the instant disclosure.

[0128] FIG. 13 depicts a partial cut-away side view of a cell body having a first sidewall portion (stable sidewall) and a second sidewall portion (cathodic sidewall) with a feeder and a protecting deposit in accordance with the instant disclosure.

[0129] FIG. 14 depicts a partial cut-away side view of a cell body having a first sidewall portion (stable sidewall) and a second sidewall portion (cathodic sidewall) with a feeder and a protecting deposit, including a directing member in accordance with the instant disclosure.

[0130] FIG. 15 depicts a partial cut-away side view of a cell body having a first sidewall portion (stable sidewall) and a second sidewall portion (cathodic sidewall) with a thermal conductor therebetween defining a frozen ledge, in accordance with the instant disclosure.

[0131] FIG. 16 depicts a partial cut-away side view of a cell body having a first sidewall portion (stable sidewall) and a second sidewall portion (cathodic sidewall) with a frozen ledge device defining a frozen ledge, in accordance with the instant disclosure.

[0132] FIG. 17 depicts a partial cut-away side view of a cell body having a sidewall which includes an anodic sidewall portion, a cathodic sidewall portion, and an insulator (e.g. electrical insulator between the anodic and cathodic sidewall portions), in accordance with the instant disclosure.

[0133] FIG. 18 depicts a partial cut-away side view of a cell body having a sidewall which includes an anodic sidewall portion, a cathodic sidewall portion, and an electrical insulator (thermal conductor material with frozen ledge) between the anodic and cathodic sidewall portions), in accordance with the instant disclosure.

[0134] FIG. 19 depicts a partial cut-away side view of a cell body having a sidewall which includes an anodic sidewall portion, a cathodic sidewall portion, and an electrical insulator (frozen ledge device with a frozen ledge) between the anodic and cathodic sidewall portions), in accordance with the instant disclosure.

[0135] FIG. 20 depicts a partial cut-away side view of a cell body having a sidewall which includes an anodic sidewall portion, a cathodic sidewall portion, and an electrical insulator (stable sidewall material/non-reactive material) between the anodic and cathodic sidewall portions), in accordance with the instant disclosure.

[0136] FIG. 21 depicts a partial cut-away side view of a cell body having a first sidewall portion which is anodic and a second sidewall portion which is cathodic, with an electrical insulator spanning the distance between the first sidewall portion and the second sidewall portion, in accordance with the instant disclosure.

[0137] FIG. 22 depicts a partial cut-away side view of a cell body having a first sidewall portion which is anodic and a second sidewall portion which is cathodic, with an electrical insulator (protecting deposit provided via feeder) spanning the distance between the first sidewall portion and the second sidewall portion, in accordance with the instant disclosure.

[0138] FIG. 23 depicts a partial cut-away side view of a cell body having a first sidewall portion which is anodic and a second sidewall portion which is cathodic, with an electrical insulator (protecting deposit provided via feeder) spanning the distance between the first sidewall portion and the second sidewall portion including a directing member, in accordance with the instant disclosure.

[0139] FIG. 24 depicts a partial cut-away side view of a cell body having a first sidewall portion which is anodic and a second sidewall portion which is cathodic, with an electrical insulator (frozen ledge device with frozen ledge) spanning the distance between the first sidewall portion and the second sidewall portion including a directing member, in accordance with the instant disclosure.

[0140] FIG. 25 depicts a partial cut-away side view of a cell body having a first sidewall portion which is anodic and a second sidewall portion which is cathodic, with an electrical insulator (frozen ledge device with frozen ledge) spanning the distance between the first sidewall portion and the second sidewall portion including a directing member, in accordance with the instant disclosure.

[0141] FIG. 26 depicts a schematic side view of an electrolysis cell in operation in accordance with the instant disclosure, depicting an active sidewall (e.g. one or more sidewalls of the instant disclosure).

[0142] FIG. 27 is a chart depicting the alumina dissolution rate (m/s) in electrolytic bath per percent alumina saturation, plotted at five (5) different temperature lines (750 C., 800 C., 850 C., 900 C., and 950 C.).

[0143] FIG. 28 is a chart of temperature and heat flux of the bath, coolant, and outlet ledge as a function of time.

[0144] FIG. 29 depicts a schematic cut-away side view of a frozen ledge device (removable/adjustable) in accordance with the instant disclosure.

[0145] FIG. 30 depicts a schematic cut-away side view of a frozen ledge device which is configured to be retained at least partly through the sidewall, in accordance with the instant disclosure.

[0146] FIG. 31 depicts a partial cut away side view of a cell with a rotary feeder, in accordance with the Examples section.

[0147] FIG. 32 depicts a partial cut away side view of a cell having an anodic sidewall portion and a cathodic sidewall portion with a protecting deposit therebetween, in accordance with one of the experiments run for the Examples section.

[0148] FIG. 33A-H depicts a partial cut away side view of various angles of the protecting deposit and the trough bottom/base (sometimes called a feed block) beneath the protecting deposit. Various angles of the protecting deposit are depicted (angling towards the second sidewall portion, angled towards the first sidewall portion, flat, angled, and the like). Also, various angles of the trough bottom/base are depicted (angling towards the second sidewall portion, angled towards the first sidewall portion, flat, angled, and the like).

[0149] FIG. 34A-D depicts a partial cut-away side view of the various configurations of the shelf top and/or second sidewall portion. FIG. 34A depicts a transverse configuration, angled towards the center of the cell (to promote cell drain). FIG. 34B depicts a transverse configuration, angled towards the sidewall (to promote retention of the feed material in the protecting deposit). FIG. 34C depicts an angled configuration (e.g. pointed). FIG. 34D depicts a curved, or arcuate upper most region of the shelf or second sidewall portion.

[0150] FIG. 35 depicts a schematic cut away side view of a transverse sidewall portion (e.g. sloped anodically polarized sidewall, depicted with feed device, trough, and second sidewall portion.

[0151] FIG. 36 depicts a schematic cut away side view of a cathodically polarized sidewall of the present disclosure, wherein the cathodically polarized sidewall extends through the bath-metal interface and the bath-vapor (sometimes called air) interface.

DETAILED DESCRIPTION

[0152] Reference will now be made in detail to the accompanying drawings, which at least assist in illustrating various pertinent embodiments of the present invention.

[0153] As used herein, electrolysis means any process that brings about a chemical reaction by passing electric current through a material. In some embodiments, electrolysis occurs where a species of metal is reduced in an electrolysis cell to produce a metal product. Some non-limiting examples of electrolysis include primary metal production. Some non-limiting examples of electrolytically produced metals include: rare earth metals, non-ferrous metals (e.g. copper, nickel, zinc, magnesium, lead, titanium, aluminum, and rare earth metals). As used herein, electrolysis cell means a device for producing electrolysis. In some embodiments, the electrolysis cell includes a smelting pot, or a line of smelters (e.g. multiple pots). In one non-limiting example, the electrolysis cell is fitted with electrodes, which act as a conductor, through which a current enters or leaves a nonmetallic medium (e.g. electrolyte bath).

[0154] As used herein, electrode means positively charged electrodes (e.g. anodes) or negatively charged electrodes (e.g. cathodes).

[0155] As used herein, anode means the positive electrode (or terminal) by which current enters an electrolytic cell. In some embodiments, the anodes are constructed of electrically conductive materials. Some non-limiting examples of anode materials include: metals, metal alloys, oxides, ceramics, cermets, carbon, and combinations thereof.

[0156] As used herein, anode assembly includes one or more anode(s) connected with, a support. In some embodiments, the anode assembly includes: the anodes, the support (e.g. refractory block and other bath resistant materials), and the electrical bus work.

[0157] As used herein, support means a member that maintains another object(s) in place. In some embodiments, the support is the structure that retains the anode(s) in place. In one embodiment, the support facilitates the electrical connection of the electrical bus work to the anode(s). In one embodiment, the support is constructed of a material that is resistant to attack from the corrosive bath. For example, the support is constructed of insulating material, including, for example refractory material. In some embodiments, multiple anodes are connected (e.g. mechanically and electrically) to the support (e.g. removably attached), which is adjustable and can be raised, lowered, or otherwise moved in the cell.

[0158] As used herein, electrical bus work refers to the electrical connectors of one or more component. For example, the anode, cathode, and/or other cell components can have electrical bus work to connect the components together. In some embodiments, the electrical bus work includes pin connectors in the anodes, the wiring to connect the anodes and/or cathodes, electrical circuits for (or between) various cell components, and combinations thereof.

[0159] As used herein, cathode means the negative electrode or terminal by which current leaves an electrolytic cell. In some embodiments, the cathodes are constructed of an electrically conductive material. Some non-limiting examples of the cathode material include: carbon, cermet, ceramic material(s), metallic material(s), and combinations thereof. In one embodiment, the cathode is constructed of a transition metal boride compound, for example TiB.sub.2. In some embodiments, the cathode is electrically connected through the bottom of the cell (e.g. current collector bar and electrical buswork). As some non-limiting examples, cathodes and/or cathodically polarized sidewall portions are constructed of: TiB.sub.2, TiB.sub.2C composite materials, boron nitride, zirconium borides, hafnium borides, graphite, and combinations thereof.

[0160] As used herein, cathode assembly refers to the cathode (e.g. cathode block), the current collector bar, the electrical bus work, and combinations thereof.

[0161] As used herein current collector bar refers to a bar that collects current from the cell. In one non-limiting example, the current collector bar collects current from the cathode and transfers the current to the electrical buswork to remove the current from the system.

[0162] As used herein, electrolyte bath refers to a liquefied bath having at least one species of metal to be reduced (e.g. via an electrolysis process). A non-limiting example of the electrolytic bath composition includes: NaFAlF.sub.3 (in an aluminum electrolysis cell), NaF, AlF.sub.3, CaF.sub.2, MgF.sub.2, LiF, KF, and combinations thereofwith dissolved alumina.

[0163] As used herein, molten means in a flowable form (e.g. liquid) through the application of heat. As a non-limiting example, the electrolytic bath is in molten form (e.g. at least about 750 C.). As another example, the metal product that forms at the bottom of the cell (e.g. sometimes called a metal pad) is in molten form.

[0164] In some embodiments, the molten electrolyte bath/cell operating temperature is: at least about 750 C.; at least about 800 C.; at least about 850 C.; at least about 900 C.; at least about 950 C.; or at least about 975 C. In some embodiments, the molten electrolyte bath/cell operating temperature is: not greater than about 750 C.; not greater than about 800 C.; not greater than about 850 C.; not greater than about 900 C.; not greater than about 950 C.; or not greater than about 975 C.

[0165] As used herein, metal product means the product which is produced by electrolysis. In one embodiment, the metal product forms at the bottom of an electrolysis cell as a metal pad. Some non-limiting examples of metal products include: aluminum, nickel, magnesium, copper, zinc, and rare earth metals.

[0166] As used herein, sidewall means the wall of an electrolysis cell. In some embodiments, the sidewall runs parametrically around the cell bottom and extends upward from the cell bottom to defines the body of the electrolysis cell and define the volume where the electrolyte bath is held. In some embodiments, the sidewall includes: an outer shell, a thermal insulation package, and an inner wall. In some embodiments, the inner wall and cell bottom are configured to contact and retain the molten electrolyte bath, the feed material which is provided to the bath (i.e. to drive electrolysis) and the metal product (e.g. metal pad). In some embodiments, the sidewall (inner sidewall) includes a polarized sidewall portion. In some embodiments, the sidewall (inner sidewall) includes a non-reactive sidewall portion (e.g. stable sidewall portion). In some embodiments, the sidewall (inner sidewall) includes: a thermal conductor portion. In some embodiments, the sidewall (inner sidewall) includes: a frozen ledge device. In some embodiments, the sidewall (inner sidewall) is configured to accept and retain a protecting deposit along a portion thereof.

[0167] As used herein, transverse means an angle between two surfaces. In some embodiments, the surfaces make an acute or an obtuse angle. In some embodiments, transverse includes an angle at or that is equal to the perpendicular angle or almost no angle, i.e. surfaces appearing as continuous (e.g. 180). In some embodiments, a portion of the sidewall (inner wall) is transverse, or angled towards the cell bottom. In some embodiments, the entire sidewall is transverse to the cell bottom.

[0168] In some embodiments, the entire wall is transverse. In some embodiments, a portion of the wall (first sidewall portion, second sidewall portion, shelf, trough, directing member) is transverse (or, sloped, angled, curved, arcuate).

[0169] In some embodiments, the shelf is transverse. In some embodiments, the second sidewall portion is transverse. Without being bound by any particular theory or mechanism, it is believed that by configuring the sidewall (first sidewall portion, second sidewall portion, trough, or shelf) in a transverse manner, it is possible to promote certain characteristics of the cell in operation (e.g. metal drain, feed material direction into the cell/towards the cell bottom). As a non-limiting example, by providing a transverse sidewall, the sidewall is configured to promote feed material capture into a protecting deposit in a trough or shelf (e.g. angled towards/or is configured to promote metal drain into the bottom of the cell. an angle to the shelf,

[0170] In some embodiments, the first sidewall portion is transverse (angled/sloped) and the second sidewall portion is not sloped. In some embodiments, the first sidewall portion is not sloped and the second sidewall portion is sloped. In some embodiments, both the first sidewall portion and the second sidewall portion are transverse (angled/sloped).

[0171] In some embodiments, the base (or feed block) is transverse (sloped or angled). In some embodiments, the upper portion of the shelf/trough or second sidewall portion is sloped, angled, flat, transverse, or curved.

[0172] As used herein, wall angle, means the angle of the inner sidewall relative to the cell bottom measurable in degrees. For example, a wall angle of 0 degrees refers to a vertical angle(or no angle). In some embodiments, the wall angle comprises: an angle (theta) from 0 degrees to about 30 degrees. In some embodiments, the wall angle comprises an angle (theta) from 0 degrees to 60 degrees. In some embodiments, the wall angle comprises an angle (theta) from about 0 to about 85 degrees.

[0173] In some embodiments, the wall angle (theta) is: at least about 5; at least about 10; at least about 15; at least about 20; at least about 25; at least about 30; at least about 35; at least about 40; at least about 45; at least about 50; at least about 55; or at least about 60. In some embodiments, the wall angle (theta) is: not greater than about 5; not greater than about 10; not greater than about 15; not greater than about 20; not greater than about 25; not greater than about 30; not greater than about 35; not greater than about 40; not greater than about 45; not greater than about 50; not greater than about 55; or not greater than about 60.

[0174] As used herein, outer shell means an outer-most protecting cover portion of the sidewall. In one embodiment, the outer shell is the protecting cover of the inner wall of the electrolysis cell. As non-limiting examples, the outer shell is constructed of a hard material that encloses the cell (e.g. steel).

[0175] As used herein, frozen refers to something that is rigid and immobilized as a result of thermal energy.

[0176] As used herein, ledge refers to projecting member.

[0177] As used herein, frozen ledge refers to something that is rigid and immobilized in a projecting configuration. In some embodiments, the frozen ledge includes a portion of the electrolytic bath adjacent to the sidewall that freezes to form a rigid ledge along a portion of the sidewall (e.g. in a generally horizontal manner). In some embodiments, the frozen ledge is formed and/or maintained by the sidewall materials (e.g. frozen ledge device or thermal conductor material) which are configured to extract/transfer heat from the bath adjacent to the sidewall. In some embodiments, the frozen ledge is formed due to temperature differences in the bath (e.g. lower temperature along the sidewall as compared to the center of the cell).

[0178] As used herein, first sidewall portion means a portion of the inner sidewall.

[0179] As used herein, second sidewall portion means another portion of the inner sidewall. In some embodiments, the second portion is a distance (e.g. longitudinally spaced) from the first portion. As one non-limiting example, the second sidewall portion is an upright member having a length and a width, wherein the second portion is spaced apart from the first portion.

[0180] In some embodiments, the second portion cooperates with the first portion to retain a material or object (e.g. protecting deposit, portion of frozen ledge).

[0181] In some embodiments, the second portion is of a continuous height, while in other embodiments, the second portion's height varies. In one embodiment, the second portion is constructed of a material that is resistant to the corrosive environment of the bath and resistant to the metal product (e.g. metal pad), and thus, does not break down or otherwise react in the bath. As some non-limiting examples, the wall is constructed of: TiB.sub.2, TiB.sub.2C, SiC, Si.sub.3N.sub.4, BN, a bath component that is at or near saturation in the bath chemistry (e.g. alumina), and combinations thereof.

[0182] In some embodiments, the second portion is electrically conductive and assists in transferring current from the bath to the cathode(s). In some embodiments, the second portion is cast, hot pressed, or sintered into the desired dimension, theoretical density, porosity, and the like. In some embodiments, the second portion is secured to one or more cell components in order to keep the second portion in place.

[0183] As used herein, directing member means a member which is configured to direct an object or material in a particular manner. In some embodiments, the directing member is adapted and configured to direct a feed material into a trough (e.g. to be retained in the trough as protecting deposit.) In some embodiments, the directing member is suspended in the cell between the first sidewall portion and the second sidewall, and above the trough in order to direct the flow of the feed material into the trough. In some embodiments, the directing member comprises a polarized sidewall portion (e.g. cathodically polarized sidewall portion or anodically polarized sidewall portion). In some embodiments, the directing member is constructed of a material (at least one bath component) which is present in the bath chemistry at or near saturation, such that in the bath the directing member is maintained. In some embodiments, the directing member is configured to attach to a frame (e.g. of bath resistant material), where the frame is configured to adjust the directing member in the cell (i.e. move the directing member laterally (e.g. up or down relative to the cell height) and/or move the directing member longitudinally (e.g. left or right relative to the trough/cell bottom).

[0184] In some embodiments, the dimension of and/or the location of the directing member is selected to promote a certain configuration of the protecting deposit and/or a predetermined feed material flow pattern into the trough. In some embodiments, the directing member is attached to the anode assembly. In some embodiments, the directing member is attached to the sidewall of the cell. In some embodiments, the directing member is attached to the feed device (e.g. frame which holds the feed device into position. As non-limiting examples, the directing member comprises a plate, a rod, a block, an elongated member form, and combinations thereof. Some non-limiting examples of directing member materials include: anode materials; SiC; SiN; and/or components which are present in the bath at or near saturation such that the directing member is maintained in the bath.

[0185] As used herein, longitudinally spaced means the placement of one object from another object in relation to a length. In some embodiments, laterally spaced (i.e. the second sidewall portion from the first sidewall portionor the trough) means: at least 1, at least 1/, at least 2, at least 2 , at least 3, at least 3 at least 4, at least 4 , at least 5, at least 5 at least 6, at least 6 at least 7, at least 7 at least 8, at least 8 at least 9, at least 9 at least 10, at least 10 at least 11, at least 11 , or at least 12.

[0186] In some embodiments, laterally spaced (i.e. the second sidewall portion from the first sidewall portionor the trough) means: not greater than 1, not greater than 1/, not greater than 2, not greater than 2 1/2, not greater than 3, not greater than 3 , not greater than 4, not greater than 4 , not greater than 5, not greater than 5 , not greater than 6, not greater than 6 , not greater than 7, not greater than 7 , not greater than 8, not greater than 8 , not greater than 9, not greater than 9 , not greater than 10, not greater than 10 , not greater than 11, not greater than 11 , or not greater than 12.

[0187] As used herein, laterally spaced means the placement of one object from another object in relation to a width.

[0188] As used herein, at least means greater than or equal to.

[0189] As used herein, not greater than means less than or equal to.

[0190] As used herein, trough means a receptacle for retaining something. In one embodiment, the trough is defined by the first sidewall portion, the second sidewall portion, and the base (or bottom of the cell). In some embodiments, the trough retains the protecting deposit. In other embodiments, the trough retains a frozen ledge or frozen portion (e.g. defined via a thermal conductor or the frozen ledge device). In some embodiments the trough retains a feed material in the form of a protecting deposit, such that the trough is configured to prevent the protecting deposit from moving within the cell (i.e. into the metal pad and/or electrode portion of the cell).

[0191] In some embodiments, the trough further comprises a height (e.g. relative to the sidewall). As non-limiting embodiments, the trough height (as measured from the bottom of the cell to the bath/vapor interface comprises: at least , at least , at least , at least 1, at least 1 , at least 1 at least 1 3/4, at least 2, at least 2 at least 2 at least 2 , at least 3, 3 at least 3 at least 3 , at least 4, 4 at least 4 at least 4 , at least 5, 5 , at least 5 , at least 5 ,or at least 6. In some embodiments, the trough height comprises: at least 6 at least 12 at least 18, at least 24, or at least 30.

[0192] As non-limiting embodiments, the trough height (as measured from the bottom of the cell to the bath/vapor interface comprises: not greater than , not greater than , not greater than 3/4, not greater than 1, not greater than 1 , not greater than 1 , not greater than 1 3/4, not greater than 2, not greater than 2 , not greater than 2 , not greater than 2 3/4, not greater than 3, 3 , not greater than 3 , not greater than 3 , not greater than 4, 4 1/4, not greater than 4 , not greater than 4 , not greater than 5, 5 , not greater than 5 1/2, not greater than 5 ,or not greater than 6. In some embodiments, the trough height comprises: not greater than 6 not greater than 12 not greater than 18, not greater than 24, or not greater than 30.

[0193] In some embodiments, the trough comprises a polarized sidewall portion (e.g. cathodically polarized sidewall portion). In some embodiments, the trough is constructed of a material (at least one bath component) which is present in the bath chemistry at or near saturation, such that in the bath it is maintained.

[0194] As used herein, protecting deposit refers to an accumulation of a material that protects another object or material. As a non-limiting example, a protecting deposit refers to the feed material that is retained in the trough. In some embodiments, the protecting deposit is: a solid; a particulate form; a sludge; a slurry; and/or combinations thereof. In some embodiments, the protecting deposit is dissolved into the bath (e.g. by the corrosive nature of the bath) and/or is consumed through the electrolytic process. In some embodiments, the protecting deposit is retained in the trough, between the first sidewall portion and the second sidewall portion. In some embodiments, the protecting deposit is configured to push the metal pad (molten metal) away from the sidewall, thus protecting the sidewall from the bath-metal interface. In some embodiments, the protecting deposit is dissolved via the bath to provide a saturation at or near the cell wall which maintains the stable/non-reactive sidewall material (i.e. composed of a bath component at or near saturation). In some embodiments the protecting deposit comprises an angle of deposit (e.g. the protecting deposit forms a shape as it collects in the trough), sufficient to protect the sidewall and provide feed material to the bath for dissolution.

[0195] As used herein, feed material means a material that is a supply that assists the drive of further processes. As one non-limiting example, the feed material is a metal oxide which drives electrolytic production of rare earth and/or non-ferrous metals (e.g. metal products) in an electrolysis cell. In some embodiments, the feed material once dissolved or otherwise consumed, supplies the electrolytic bath with additional starting material from which the metal oxide is produced via reduction in the cell, forming a metal product. In some embodiments, the feed material has two non-limiting functions: (1) feeding the reactive conditions of the cell to produce metal product; and (2) forming a feed deposit in the channel between the wall at the inner sidewall to protect the inner sidewall from the corrosive bath environment. In some embodiments, the feed material comprises alumina in an aluminum electrolysis cell. Some non-limiting examples of feed material in aluminum smelting include: smelter grade alumina (SGA), alumina, tabular aluminum, and combinations thereof. In the smelting of other metals (non-aluminum), feed materials to drive those reactions are readily recognized in accordance with the present description. In some embodiments, the feed material is of sufficient size and density to travel from the bath-air interface, through the bath and into the trough to form a protecting deposit.

[0196] As used herein, average particle size refers to the mean size of a plurality of individual particles. In some embodiments, the feed material in particulate (solid) form having an average particle size. In one embodiment, the average particle size of the feed material is large enough so that it settles into the bottom of the cell (e.g. and is not suspended in the bath or otherwise float in the bath). In one embodiment, the average particle size is small enough so that there is adequate surface area for surface reactions/dissolution to occur (e.g. consumption rate).

[0197] As used herein, feed rate means a certain quantity (or amount) of feed in relation to a unit of time. As one non-limiting example, feed rate is the rate of adding the feed material to the cell. In some embodiments, the size and/or position of the protecting deposit is a function of the feed rate. In some embodiment, the feed rate is fixed. In another embodiment, the feed rate is adjustable. In some embodiments, the feed is continuous. In some embodiments, the feed is discontinuous.

[0198] As used herein, consumption rate means a certain quantity (or amount) of use of a material in relation to a unit of time. In one embodiment, consumption rate is the rate that the feed material is consumed by the electrolysis cell (e.g. by the bath, and/or consumed to form metal product).

[0199] In some embodiments, the feed rate is higher than the consumption rate. In some embodiment, the feed rate is configured to provide a protecting deposit above the bath-air interface.

[0200] As used herein, feeder (sometimes called a feed device) refers to a device that inputs material (e.g. feed) into something. In one embodiment, the feed device is a device that feeds the feed material into the electrolysis cell. In some embodiments, the feed device is automatic, manual, or a combination thereof. As non-limiting examples, the feed device is a curtain feeder or a choke feeder. As used herein, curtain feeder refers to a feed device that moves along the sidewall (e.g. with a track) to distribute feed material. In one embodiment, the curtain feeder is movably attached so that it moves along at least one sidewall of the electrolysis cell. As used herein, choke feeder refers to a feed device that is stationary on a sidewall to distribute feed material into the cell. In some embodiments, the feed device is attached to the sidewall by an attachment apparatus. Non-limiting examples include braces, and the like.

[0201] In some embodiments, the feed device is automatic. As used herein, automatic refers to the capability to operate independently (e.g. as with machine or computer control). In some embodiments, the feed device is manual. As used herein, manual means operated by human effort.

[0202] As used herein, feed block refers to feed material in solid form (e.g. cast, sintered, hot pressed, or combinations thereof). In some embodiments, the base of the trough comprises a feed block. As one non-limiting example, the feed block is made of alumina. In some embodiments, the feed block is a solid block (e.g. of any shape or dimension) of the feed material and/or another bath component.

[0203] As used herein, polarized means a material that has a positive or negative electric potential imparted in it.

[0204] As used herein, polarized sidewall refers to a wall portion that is polarized to have a charge. In one embodiment, polarized sidewall is a portion of the inner wall of the cell that has a positive polarization (e.g. anodic or anodically polarized), negative polarization (cathodic or cathodically polarized), or combination thereof. In some embodiments, the polarized sidewall assists in the electrolysis process. In some embodiments, the polarized sidewall portions include a first material and a second material, where the first material is different from the second material.

[0205] In some embodiments, the polarized sidewall comprises a percentage of the total sidewall/percentage of the total surface area of the sidewall (e.g. portion of the sidewall attached to the thermal insulation package). In some embodiments, the polarized sidewall is: at least about 1%; at least about 5%; at least about 10%; at least about 15%; at least about 20%; at least about 25%; at least about 30%; at least about 35%; at least about 40%; at least about 45%; at least about 50%; at least about 55%; at least about 60%; at least about 65%; at least about 70%; at least about 75%; at least about 80%; at least about 85%; at least about 90%; at least about 95%; or 100% of the surface area of the sidewall (i.e. sidewall configured to attach to the thermal insulation package, or second sidewall portion).

[0206] In some embodiments, the polarized sidewall is: not greater than about 1%; not greater than about 5%; not greater than about 10%; not greater than about 15%; not greater than about 20%; not greater than about 25%; not greater than about 30%; not greater than about 35%; not greater than about 40%; not greater than about 45%; not greater than about 50%; not greater than about 55%; not greater than about 60%; not greater than about 65%; not greater than about 70%; not greater than about 75%; not greater than about 80%; not greater than about 85%; not greater than about 90%; not greater than about 95%; or 100% of the surface area of the sidewall (i.e. sidewall configured to attach to the thermal insulation package, or second sidewall portion).

[0207] As used herein, anodic sidewall (also called an anodically polarized sidewall), means a sidewall material that has a positive charge on it (or through it) so that the sidewall acts in an anodic fashion in an electrolysis cell. In some embodiments, the anodic sidewall is located above the cell bottom. In some embodiments, the anodic sidewall is located at a height which is above the metal pad. In some embodiments, the anodic sidewall is located at a height above the bath-metal interface. In some embodiments, the electrically connected portion of the anodic sidewall is located in an elevated position along the inner sidewall, remote from the bottom.

[0208] As used herein, anodic sidewall electrical connection means the electrical connection which provides the positive charge to the surface of the anodic sidewall. In some embodiments, the electrical connection supplies current to the anodic sidewall. In some embodiments, the electrical connection includes a conductor pin. In some embodiments, the electrical connection includes a conductor bar. As one non-limiting example, the electrical connection is the collector bar and the conductor pin, which are embedded inside of the anodic sidewall.

[0209] As used herein, cathodic sidewall, means a sidewall that has a negative charge on it (or through it) so that it acts in a cathodic fashion in an electrolysis cell. In some embodiments, the cathodic sidewall is in communication with the cell bottom. In some embodiments, the cathodic sidewall is in communication with the metal product/metal pad. In some embodiments, the cathodic sidewall is at a height which is below the bath-air interface. In some embodiments, the cathodic sidewall is located in the electrolyte bath.

[0210] As used herein, cathodic sidewall electrical connection means the electrical connection which provides the negative charge to the surface of the anodic sidewall. In some embodiments, the electrical connection removes current from the cathodic sidewall. In some embodiments, the electrical connection includes a conductor bar. As one non-limiting example, the electrical connection is the collector bar, which is embedded inside of the cathodic sidewall. In some embodiments, the electrical connection is provided by contact of (e.g. mechanical connection/attachment) of the cathodic sidewall to the cathode. In some embodiments, the electrical connection is provided by the contact of the cathodic sidewall to the metal pad, which is cathodic due to its contact with the cathode.

[0211] As used herein, non-polarized means an object or material which is not configured to carry current (i.e. is not anodically or cathodically polarized). In some embodiments, the non-polarized sidewall is configured to provide electrical insulation to at least one (or two) polarized sidewall portions. Some non-limiting examples of a non-polarized material include: a thermal conductor material, a non-reactive material, and a frozen ledge device.

[0212] In some embodiments, the non-polarized sidewall comprises a percentage of the total sidewall/percentage of the total surface area of the sidewall (e.g. portion of the sidewall attached to the thermal insulation package). In some embodiments, the non-polarized sidewall is: at least about 1%; at least about 5%; at least about 10%; at least about 15%; at least about 20%; at least about 25%; at least about 30%; at least about 35%; at least about 40%; at least about 45%; at least about 50%; at least about 55%; at least about 60%; at least about 65%; at least about 70%; at least about 75%; at least about 80%; at least about 85%; at least about 90%; at least about 95%; or 100% of the surface area of the sidewall (i.e. sidewall configured to attach to the thermal insulation package, or second sidewall portion).

[0213] In some embodiments, the non-polarized sidewall is: not greater than about 1%; not greater than about 5%; not greater than about 10%; not greater than about 15%; not greater than about 20%; not greater than about 25%; not greater than about 30%; not greater than about 35%; not greater than about 40%; not greater than about 45%; not greater than about 50%; not greater than about 55%; not greater than about 60%; not greater than about 65%; not greater than about 70%; not greater than about 75%; not greater than about 80%; not greater than about 85%; not greater than about 90%; not greater than about 95%; or 100% of the surface area of the sidewall (i.e. sidewall configured to attach to the thermal insulation package, or second sidewall portion).

[0214] As used herein, thermal conductor refers to a substance (or medium) that conducts thermal energy (e.g. heat). In some embodiments, the thermal conductor material is a portion of the sidewall. In some embodiments, the thermal conductor material is configured to transfer heat from the molten electrolyte bath through its body, thus removing heat from the cell. In some embodiments, due to the heat transfer across the face of the thermal conductor, a frozen ledge portion is generated at the bath-thermal conductor interface. In some embodiments, the frozen ledge defined by the thermal conductor acts as an electrical insulator along a portion of the sidewall of the cell. Some non-limiting examples of thermal conductor materials include: SiC, graphite, metal, or metal alloys, Si.sub.3N.sub.4, BN, stainless steel, metal, and metal alloy, and combinations thereof.

[0215] As used herein, insulator, means a material or an object that does not easily allow electricity, to pass through it. As a non-limiting example, an insulator refers to a material that is resistant to the transfer of electricity. In some embodiments of the instant disclosure, insulators are provided along portions of the sidewall to electrically insulate one portion from another (e.g. an anodically polarized sidewall portion from a cathodically polarized sidewall portion; an anodically polarized sidewall portion from a cell bottom (or metal pad); or combinations thereof. Some non-limiting examples of insulators include: non-reactive (e.g. stable) sidewall materials, thermal conductor sidewalls, polarized sidewalls, and/or a frozen ledge device.

[0216] As used here, non-reactive sidewall refers to a sidewall which is constructed or composed of (e.g. coated with) a material which is stable (e.g. non-reactive, inert, dimensionally stable, and/or maintained) in the molten electrolyte bath at cell operating temperatures (e.g. above 750 C. to not greater than 960 C.). In some embodiments, the non-reactive sidewall material is maintained in the bath due to the bath chemistry. In some embodiments, the non-reactive sidewall material is stable in the electrolyte bath since the bath comprises the non-reactive sidewall material as a bath component in a concentration at or near its saturation limit in the bath. In some embodiments, the non-reactive sidewall material comprises at least one component that is present in the bath chemistry. In some embodiments, the bath chemistry is maintained by feeding a feed material into the bath, thus keeping the bath chemistry at or near saturation for the non-reactive sidewall material, thus maintaining the sidewall material in the bath.

[0217] Some non-limiting examples of non-reactive sidewall materials include: Al; Li; Na; K; Rb; Cs; Be; Mg; Ca; Sr; Ba; Sc; Y; La; or Ce-containing materials, and combinations thereof. In some embodiments, the non-reactive material is an oxide of the aforementioned examples. In some embodiments, the non-reactive material is a halide salt and/or fluoride of the aforementioned examples. In some embodiments, the non-reactive material is an oxofluoride of the aforementioned examples. In some embodiments, the non-reactive material is pure metal form of the aforementioned examples. In some embodiments, the non-reactive sidewall material is selected to be a material (e.g. Ca, Mg) that has a higher electrochemical potential than (e.g. cations of these materials are electrochemically more noble than) the metal product being produced (e.g. Al), the reaction of the non-reactive sidewall material is less desirable (electrochemically) than the reduction reaction of Alumina to Aluminum. In some embodiments, the non-reactive sidewall is made from castable materials. In some embodiments, the non-reactive sidewall is made of sintered materials.

Example: Bench Scale Study: Side Feeding

[0218] Bench scale tests were completed to evaluate the corrosion-erosion of an aluminum electrolysis cell. The corrosion-erosion tests showed that alumina, and chromia-alumina materials were preferentially attacked at the bath-metal interface. Also, it was determined that the corrosion-erosion rate at the bath-metal interface is accelerated dramatically when alumina saturation concentration is low (e.g. below about 95 wt. %). With a physical barrier of feeding materials, i.e. to feed increase the alumina saturation concentration, the barrier (e.g. of alumina particles) operated to keep alumina saturated at bath-metal interface to protect the sidewall from being dissolved by the bath. Thus, the sidewall at the bath-metal interface is protected from corrosive-erosive attack and the aluminum saturation concentration was kept at about 98 wt. %. After performing electrolysis for a period of time, the sidewall was inspected and remained intact.

Example: Pilot Scale Test: Automated Side feeding with Rotary Feeder

[0219] A single hall cell was operated continuously for about 700 hr with a trough along the sidewall around the perimeter of the cell (e.g. via a rotary feeder). The feeder included a hopper, and rotated along the sidewall to feed the entire sidewall (along one sidewall). A feed material of tabular alumina was fed into the cell at a location to be retained in the trough by an automatic feeder device. After electrolysis was complete, the sidewall was inspected and found intact (i.e. the sidewall was protected by the side feeding). The rotary feeder along the sidewall is depicted in FIG. 31.

Example: Full Pot Test Side Feeding (Manual)

[0220] A commercial scale test on sidewall feeding was operated continuously for a period of time (e.g. at least one month) with a trough along the sidewall via manual feeding. A feed material of tabular alumina was fed into the cell manually at a location adjacent to the sidewall such that the alumina was retained in a trough in the cell, located adjacent to the sidewall. Measurements of the sidewall profile showed minimum corrosion-erosion of the sidewall above the trough, and trough profile measurements indicated that the trough maintained its integrity throughout the operation of the cell. Thus, the manually fed alumina protected the metal-bath interface of the sidewall of the cell from corrosion-erosion. An autopsy of the cell was performed to conclusively illustrate the foregoing.

Example: Polarized Sidewalls with Side Feeding

[0221] Bench tests and pilot tests were performed (e.g. 100 A cell up to 25 kA cell), with some tests running for as long as nine months. the Sidewall included an anodic portion and a cathodic portion, with a feeder providing a protecting deposit to act as an insulator therebetween, as depicted in FIGS. 22 and 33. After the cell was run, the sidewalls were evaluated and confirmed to be intact.

Example: Frozen Ledge Device

[0222] A pilot scale test was performed with a frozen ledge device (e.g. frozen finger) due to the scale-down, in a crucible reactor. The frozen ledge device operated to form a frozen portion of bath along the surface of the frozen ledge device. FIGS. 29-30 depict the frozen ledge device and the experimental set up within the crucible reactor.

[0223] While various embodiments of the present invention have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention.

REFERENCE NUMBERS

[0224] Cell 10 [0225] Anode 12 [0226] Cathode 14 [0227] Electrolyte bath 16 [0228] Metal pad 18 [0229] Cell body 20 [0230] Electrical bus work 22 [0231] Anode assembly 24 [0232] Current collector bar 40 [0233] Active sidewall 30 [0234] Sidewall 38 (e.g. includes active sidewall and thermal insulation package) [0235] Bottom 32 [0236] Outer shell 34 [0237] Polarized sidewall 50 [0238] Feed block 60 [0239] Anodic sidewall 70 [0240] Cathodic sidewall 52 [0241] Bath-air (vapor) interface 26 [0242] Metal-bath interface 28 [0243] Frozen ledge device 80 [0244] Inlet 82 [0245] Outlet 84 [0246] Body 86 [0247] Outer wall 92 (contacts electrolyte) [0248] Heat absorption section 88 (comprising thermal conducting material e.g. steel, SiC, graphite sleeve) [0249] Channel 90 [0250] Pump 100 [0251] Energy output 102 [0252] Coolant 96 [0253] Expanded areas (e.g. fins) 104 [0254] Heat exchanger 98