DIRECT ELECTROCHEMICAL REDUCTION OF IMPURE METAL COMPOUNDS IN MOLTEN SALTS
20260043164 ยท 2026-02-12
Assignee
Inventors
- Sachin S. SHIRPURKAR (Beavercreek, OH, US)
- Badri Shyam (Bexley, OH, US)
- Joseph P. HARING (Grove City, OH, US)
- Richard J. ROBINSON (Dayton, OH, US)
- Heng Yang (Beavercreek, OH, US)
- John D. BUSBEE (Washington Township, OH, US)
- Mark DAROUX (Kettering, OH, US)
- Wyatt Norman LEE (Beavercreek, OH, US)
- Larry Alan SPICKARD (Dayton, OH, US)
- Martin RUCIDLO (Oregonia, OH, US)
Cpc classification
C25C3/34
CHEMISTRY; METALLURGY
International classification
C25C3/34
CHEMISTRY; METALLURGY
C25C7/00
CHEMISTRY; METALLURGY
Abstract
An apparatus and related methods for continuous electrodeposition of metals from impure metal feedstocks are provided. Elemental metals (e.g., Co, Cu) can be deposited from metal feedstocks (e.g., metal compounds such as hydroxides, oxyhydroxides, oxides, or sulfides; ores, including concentrates and mine wastes; tailings; alloys; recycled waste; or scrap metal) in a molten salt electrolyte. An apparatus for continuous electrodeposition comprises: a working electrode comprising a rotary drum having a central axis and a lateral surface, wherein the rotary drum is configured to rotate about the central axis; a counter electrode; and a vessel with an electrolyte bath disposed therein, the electrolyte bath comprising a molten salt electrolyte, wherein the lateral surface of the working electrode is configured to be at least partially submerged in the electrolyte bath. Methods of the present disclosure enable recovery of metals from low concentrations or via processing of ores or dilute waste streams.
Claims
1. An electrodeposition apparatus, comprising: a working electrode comprising a rotary drum having a central axis and a lateral surface, wherein the rotary drum is configured to rotate about the central axis; a counter electrode; and a vessel with an electrolyte bath disposed therein, the electrolyte bath comprising a molten salt electrolyte, wherein the lateral surface of the working electrode is configured to be at least partially submerged in the electrolyte bath.
2. The electrodeposition apparatus of claim 1, wherein the counter electrode is substantially concentric with the lateral surface of the working electrode.
3. The electrodeposition apparatus of claim 1, further comprising a scraping member configured to separate electrodeposited metal from the lateral surface of the rotary drum.
4. The electrodeposition apparatus of claim 1, further comprising a fluid flow apparatus configured to transport electrolyte bath into the vessel and/or out of the vessel.
5. The electrodeposition apparatus of claim 1, wherein the electrolyte bath is isolated from ambient atmosphere and is in contact with an inert atmosphere.
6. The electrodeposition apparatus of claim 1, further comprising: a potentiostat configured to control a voltage across the working electrode and the counter electrode; and/or a galvanostat configured to control a current flowing between the working electrode and the counter electrode.
7. The electrodeposition apparatus of claim 1, wherein the molten salt electrolyte comprises one or more of LiOH, NaOH, KOH, and CsOH.
8. The electrodeposition apparatus of claim 1, wherein the molten salt electrolyte comprises one or more molten salt halides, sulfates, carbonates, borates, or nitrates.
9. The electrodeposition apparatus of claim 1, wherein the electrolyte bath further comprises a feedstock comprising a first metal, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock.
10. A method for electrodeposition of a first metal onto an electrode from a feedstock comprising the first metal, the method comprising: providing the feedstock to a molten salt electrolyte, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock; contacting a working electrode and a counter electrode with the molten salt electrolyte comprising the feedstock; and applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, wherein: the working electrode comprises a rotary drum having a central axis and a lateral surface, wherein the rotary drum rotates about the central axis while the voltage is applied; and at least a portion of the lateral surface is submerged in the molten salt electrolyte while the rotary drum is rotated about the central axis.
11. The method of claim 10, wherein electrodeposited metal is removed from a portion of the lateral surface not submerged in the electrolyte bath before the portion is reintroduced into the electrolyte bath.
12. The method of claim 10, wherein the first metal has an average oxidation state of 1+ to 4+ in the feedstock.
13. The method of claim 10, wherein: the molten salt electrolyte comprises one or more of LiOH, NaOH, KOH, and CsOH; or the molten salt electrolyte comprises one or more molten salt sulfates, nitrates, halides, carbonates, or borates.
14. The method of claim 10, wherein the feedstock further comprises a second metal, wherein the second metal has an average oxidation state of 4+ or less in the feedstock.
15. The method of claim 14, wherein after the first metal is electrodeposited onto the working electrode in elemental form, a second voltage is applied across the working electrode and the counter electrode, wherein the second voltage is sufficient to electrodeposit the second metal onto the working electrode in elemental form.
16. The method of claim 14, wherein the voltage applied across the working electrode and the counter electrode is sufficient to co-deposit the first metal and the second metal onto the working electrode in elemental form.
17. The method of claim 10, wherein: the feedstock comprises one or more alloys, ores, concentrates, mine wastes, or tailings; or the feedstock comprises scrap comprising the first metal, and the counter electrode comprises a porous container in contact with the scrap, wherein the first metal is oxidized at the counter electrode via application of an oxidizing voltage before being electrodeposited in elemental form onto the working electrode via application of a reducing voltage.
18. The method of claim 10, wherein: the voltage applied across the working electrode and the counter electrode is held constant; or the voltage applied across the working electrode or the counter electrode is pulsed; or a current flowing between the working electrode and the counter electrode is held constant; or the current flowing between the working electrode and the counter electrode is pulsed.
19. The method of claim 10, wherein the molten salt electrolyte is in contact with an inert atmosphere and is isolated from ambient atmosphere.
20. A method of recycling a metal from a feedstock, the method comprising: (a) solubilizing a first metal from the feedstock to obtain a metal composition, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock; and (b) electrodepositing the first metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: providing the metal composition to a molten salt electrolyte comprising one or more molten salt hydroxides, sulfates, nitrates, halides, carbonates, or borates; contacting a working electrode and a counter electrode with the molten salt electrolyte; and applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, wherein: the working electrode comprises a rotary drum having a central axis and a lateral surface, wherein the rotary drum is rotated about the central axis; and at least a portion of the lateral surface is submerged in the molten salt electrolyte while rotary drum is rotated about the central axis.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Various objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the detailed description taken in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
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DETAILED DESCRIPTION
[0081] Reference will now be made in detail to some specific embodiments contemplated by the present disclosure. While various embodiments are described herein, it will be understood that it is not intended to limit the present technology to the described embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the technology as defined by the appended claims.
[0082] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present technology. Particular exemplary embodiments of the present technology may be implemented without some or all of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the present technologies.
[0083] Various techniques and mechanisms of the present technology will sometimes be described in singular form for clarity. However, it should be noted that some embodiments include multiple iterations of a technique or multiple instantiations of a mechanism unless noted otherwise.
[0084] Aspects of the present disclosure provide an electrochemical method and apparatus to extract and purify one or more metals from an electrolyte comprising a molten salt electrolyte (e.g., alkali hydroxide salts). The metals are obtained by electrochemical reduction at a working electrode at lower temperatures (typically below 500 C.) thereby reducing water consumption, energy consumption, and costs, when compared to traditional hydrometallurgy or pyrometallurgy routes. The apparatus and methods of the present disclosure are highly effective for several technologically important metals having favorable chemical and electrochemical behavior in molten salt electrolytes, and which are otherwise challenging to reduce to elemental form with good purity (e.g., greater than 90%) and yield due to their highly stable configurations in certain ores and feedstocks.
Continuous Electrodeposition Apparatus and Related Methods
[0085] In one aspect, this disclosure relates to an apparatus and related methods of operation for continuous electrodeposition of elemental metals from feedstocks (e.g., ores, metal compounds, mine wastes, electronic waste, spent batteries, etc.). The present disclosure introduces, for the first time, an apparatus and related electrodeposition methods that enable continuous electrodeposition of elemental metals at industrially relevant scales, directly from ores, concentrates, mine tailings, scrap metal, electronic waste, spent batteries, and other feedstocks, using a molten salt electrolyte. Coupling a continuous-flow electrochemical cell with molten salt electrolytes (e.g., molten hydroxide salts) was long considered impractical because of the extreme corrosivity of the molten salt electrolyte, elevated operating temperatures, and the attendant safety risks. For instance, the combination of corrosivity and high temperatures (e.g., above 30 C.) poses human health risks (e.g., vapors causing severe respiratory and ocular irritation), as well as the possibility of thermal stress, which can lead to cracking and distortion of containment vessels and seals. Moreover, the intense chemical corrosivity poses the risk that the electrolyte will attack metals and ceramics, thereby compromising piping, pumps, housings, causing equipment damage and corrosion products that can contaminate the electrolyte and deposit unpredictably on the electrodes, thereby degrading process control.
[0086] By employing corrosion-resistant construction materials and purpose-built pumps and seals that remain stable under prolonged exposure to molten salts, the disclosed system enables single-step metal recovery in a continuous mode at industrial scale, overcoming the simultaneous risks outlined above. Owing to the formidable technical and safety challenges posed by molten salts (e.g., hydroxide molten salts), no comparable continuous electrorefining process was previously known.
[0087] In one aspect, the present disclosure relates to use of a continuous electrochemical current in a molten caustic electrolyte at a rotating metal electrode to convert dissolved metal species to elemental metal via electrochemical reduction. In one aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to an electrodeposition apparatus, comprising: [0088] a working electrode comprising a rotary drum having a central axis and a lateral surface, wherein the rotary drum is configured to rotate about the central axis; [0089] a counter electrode; and [0090] a vessel with an electrolyte bath disposed therein, the electrolyte bath comprising a molten salt electrolyte, [0091] wherein the lateral surface of the working electrode is configured to be at least partially submerged in the electrolyte bath.
[0092] Referring now to
[0097] In some embodiments, the counter electrode 108 has an arc shape such that a surface of the counter electrode opposite the working electrode 102 is separated from the lateral surface 106 of the working electrode by a substantially uniform distance throughout the electrodeposition process. In some embodiments, the distance between counter electrode and working electrode may be adjustable. The working volume between the working electrode and counter electrode is filled with molten salt electrolyte. In some embodiments, the lateral surface 106 of the rotary drum is corrugated.
[0098] In some embodiments, the apparatus further comprises a scraping member 114 configured to separate electrodeposited metal from the lateral surface 106 of the rotary drum as the rotary drum rotates about the central axis 104. Electrodeposited material (e.g., metal in elemental form) may be separated from the lateral surface of the drum using the scraping member and directed to a collector 116 for further processing (e.g., drying, milling, further chemical treatment, storage, etc.).
[0099] In some embodiments, the apparatus further comprises a directed gas stream apparatus (air knife) 118 configured to remove residual molten salt electrolyte from the electrodeposited material as it emerges from the electrolyte bath on the lateral surface 106 of the working electrode. The air knife directs a stream of heated gas (e.g., air, inert gas) onto the newly emerged electrodeposited material. The heated gas is maintained at or above the melting point of the molten salt, thereby heating residual electrolyte and maintaining the electrolyte in a liquid state, which permits removal by gravity (i.e., the liquid molten salt electrolyte flows back down into the electrolyte bath). In some embodiments, the air knife is oriented such that the direction of the heated gas stream further directs the flow of liquid electrolyte from the electrodeposited material back down into the electrolyte bath. In some embodiments, the pressurized gas stream directed from the air knife has a pressure of 10 to 80 psi.
[0100] By continuously removing electrodeposited metal from the lateral surface of the rotary drum as the electrodeposited material is rotated out of the bath, the surface of the working electrode is continuously regenerated, thereby permitting continuous electrodeposition to take place on a clean electrode surface with a constant current density, thereby permitting continuous production of a uniform, high-purity metal product (e.g., in the form of a foil or powder). In effect, at all times, a portion of the lateral surface of the rotary drum is submerged in the molten salt electrolyte, undergoing electrodeposition, while a portion of the rotary drum is out of the electrolyte, undergoing separating of electrodeposited material via a scraping member, permitting continuous, industrial-scale electrodeposition of refined metals from impure feedstocks.
[0101] Thus, the continuous electrodeposition apparatus permits uninterrupted electrodeposition of material (e.g., elemental metals or metal compounds such as oxides, hydroxides, oxyhydroxides, and sulfides) by reducing one or more metals onto a working electrode from an impure feedstock in a molten salt electrolyte (e.g., comprising hydroxides) via: (1) continuous rotation of a rotary drum electrode through the electrolyte bath to permit electrodeposition onto one portion of the lateral surface of the working electrode; and (2) continuous removal of electrodeposited material from the lateral surface of the working electrode on a portion of the lateral surface that is not submerged in the electrolyte bath. This operation offers several advantages. For one, fresh working electrode surface is constantly submerged in the electrolyte bath, allowing for uniform deposition onto the same electrode surface, with the same electrode surface area and same electrode morphology, for the entirety of the electrodeposition operation. Moreover, removal of electrodeposited material using a scraping member permits removal of the electrodeposited material before further unwanted reactions with the molten salt electrolyte can occur, resulting in a known product of known composition and high purity.
[0102] Referring again to
[0103] In some embodiments, the apparatus further comprises a containment apparatus configured to isolate the electrolyte bath from the ambient atmosphere, wherein the electrolyte bath is in contact with an inert atmosphere. In some embodiments, the inert atmosphere comprises nitrogen gas or argon gas at a concentration of at least about 97 vol. %, at least about 97.5 vol. %, at least about 98 vol. %, at least about 98.5 vol. %, at least about 99 vol. %, at least about 99.1 vol. %, at least about 99.2 vol. %, at least about 99.3 vol. %, at least about 99.4 vol. %, at least about 99.5 vol. %, at least about 99.6 vol. %, at least about 99.7 vol. %, at least about 99.8 vol. %, at least about 99.9 vol. %. In some embodiments, the inert atmosphere comprises oxygen gas or water vapor at a concentration of no greater than about 0.01 vol. %, no greater than about 0.02 vol. %, no greater than about 0.03 vol. %, no greater than about 0.04 vol. %, no greater than about 0.05 vol. %, no greater than about 0.06 vol. %, no greater than about 0.07 vol. %, no greater than about 0.08 vol. %, no greater than about 0.09 vol. %, no greater than about 0.1 vol. %, no greater than about 0.15 vol. %, no greater than about 0.2 vol. %, no greater than about 0.25 vol. %, no greater than about 0.3 vol. %, no greater than about 0.35 vol. %, no greater than about 0.4 vol. %, no greater than about 0.45 vol. %, no greater than about 0.5 vol. %, no greater than about 0.6 vol. %, no greater than about 0.7 vol. %, no greater than about 0.8 vol. %, no greater than about 0.9 vol. %, no greater than about 1.0 vol. %, no greater than about 1.5 vol. %, no greater than about 2.0 vol. %, no greater than about 2.5 vol. %, or no greater than about 3.0 vol. %.
[0104] In some embodiments, the apparatus further comprises: a potentiostat configured to control a voltage across the working electrode and the counter electrode; and/or a galvanostat configured to control a current flowing between the working electrode and the counter electrode.
[0105] Continuous electrorefining offers several key advantages over batch processes, including: [0106] higher mass transfer and productivity (yield/throughput) than traditional electrowinning; [0107] lower operating temperature and energy utilization than other molten salt direct electrochemical reduction; [0108] broad solvency of molten salt electrolyte for dissolving a broad range of metal compounds; [0109] scalable and continuous processing; [0110] improved safety; and [0111] reduced environmental risk due to low CO.sub.2 footprint, low water consumption/waste, elimination of flammables, and reduced pressure.
[0112] Referring again to
[0113] The electrified components are isolated from the vessel, where needed, using insulators such as ceramic sheets, ceramic washers, or other insulating mechanisms.
[0114] The cathode (rotary drum) and the anode may comprise any suitable materials for facilitating efficient and continuous electrorefining of metal(s) from the impure metal feedstock(s). In some embodiments, the cathode and anode comprise stainless steel of any suitable grade for practicality, superior chemical and electrochemical stability, excellent corrosion resistance, and economic feasibility. For instance, in some embodiments, the cathode (rotary drum) and/or anode are both constructed using SS304.
[0115] Upon application of a voltage across the CERC, solvated raw materials are consumed from the molten salt electrolyte, leading to electroplating of products on the cathode. The plated product (reduced metal in the form of elemental metal or metal compounds such as oxides, hydroxides, oxyhydroxides, or sulfides) is collected using a scraping member contacting the drum surface, which delivers the product into the collection bin. (See
[0116] The CERC may operate at steady state to extract and harvest a metal product from a molten salt bath. In some embodiments, the molten salt batch comprises molten salt hydroxides (e.g., NaOHKOH) according to any of the embodiments disclosed above.
[0117] In some embodiments, the molten salt bath is maintained at a temperature of at least about 150 C., at least about 160 C., at least about 170 C., at least about 180 C., at least about 190 C., at least about 200 C., at least about 210 C., at least about 220 C., at least about 230 C., at least about 240 C., at least about 250 C., at least about 260 C., at least about 270 C., at least about 280 C., at least about 290 C., at least about 300 C., at least about 310 C., at least about 320 C., at least about 330 C., at least about 340 C., at least about 350 C., at least about 360 C., at least about 370 C., at least about 380 C., at least about 390 C., at least about 400 C., or any range or value including and/or in between any two of these values.
[0118] In some embodiments, the molten salt bath is maintained at a temperature of less than or equal to about 400 C., less than or equal to about 390 C., less than or equal to about 380 C., less than or equal to about 370 C., less than or equal to about 360 C., less than or equal to about 350 C., less than or equal to about 340 C., less than or equal to about 330 C., less than or equal to about 320 C., less than or equal to about 310 C., less than or equal to about 300 C., less than or equal to about 290 C., less than or equal to about 280 C., less than or equal to about 270 C., less than or equal to about 260 C., less than or equal to about 250 C., less than or equal to about 240 C., less than or equal to about 230 C., less than or equal to about 220 C., less than or equal to about 210 C., less than or equal to about 200 C., less than or equal to about 190 C., less than or equal to about 180 C., less than or equal to about 170 C., less than or equal to about 160 C., less than or equal to about 150 C., or any range or value including and/or in between any two of these values.
[0119] In some embodiments, the molten salt bath is maintained at a temperature of about 150 C. to about 400 C., about 170 C. to about 370 C., about 200 C. to about 350 C., about 230 C. to about 300 C., about 230 C. to about 260 C., or any range or value therein.
[0120] In some embodiments, the CERC is operated at a variable, uniform potential (12 V, 10 V, 8 V, 6 V, 5 V, 4 V, 3 V, 2 V, 1 V, 0.5 V) with high electrolyte flow between a cylindrical cathode and a sectioned cylinder anode. (See
[0121] The current density at the anode and/or the cathode may be selected to afford efficient and scalable electrorefining of metal(s) at the electrodes. In some embodiments, the current density may be at least about 1 mA/cm.sup.2, at least about 2 mA/cm.sup.2, at least about 3 mA/cm.sup.2, at least about 4 mA/cm.sup.2, at least about 5 mA/cm.sup.2, at least about 10 mA/cm.sup.2, at least about 15 mA/cm.sup.2, at least about 20 mA/cm.sup.2, at least about 25 mA/cm.sup.2, at least about 30 mA/cm.sup.2, at least about 35 mA/cm.sup.2, at least about 40 mA/cm.sup.2, at least about 45 mA/cm.sup.2, at least about 50 mA/cm.sup.2, at least about 100 mA/cm2, at least about 150 mA/cm.sup.2, at least about 200 mA/cm.sup.2, at least about 250 mA/cm.sup.2, or any range or value including and/or in between any two of these values.
[0122] In some embodiments, the current density is less than or equal to about 250 mA/cm.sup.2, less than or equal to about 200 mA/cm.sup.2, less than or equal to about 150 mA/cm.sup.2, less than or equal to about 100 mA/cm.sup.2, less than or equal to about 50 mA/cm.sup.2, less than or equal to about 45 mA/cm.sup.2, less than or equal to about 40 mA/cm.sup.2, less than or equal to about 35 mA/cm.sup.2, less than or equal to about 30 mA/cm.sup.2, less than or equal to about 25 mA/cm.sup.2, less than or equal to about 20 mA/cm.sup.2, less than or equal to about 15 mA/cm.sup.2, less than or equal to about 10 mA/cm.sup.2, less than or equal to about 5 mA/cm.sup.2, less than or equal to about 4 mA/cm.sup.2, less than or equal to about 3 mA/cm.sup.2, less than or equal to about 2 mA/cm.sup.2, less than or equal to about 1 mA/cm.sup.2, or any range or value including and/or in between any two of these values.
[0123] In some embodiments, the current density is about 1 mA/cm.sup.2 to about 250 mA/cm.sup.2, about 1 mA/cm.sup.2 to about 200 mA/cm.sup.2, about 1 mA/cm.sup.2 to about 150 mA/cm.sup.2, about 1 mA/cm.sup.2 to about 100 mA/cm.sup.2, about 1 mA/cm.sup.2 to about 50 mA/cm.sup.2, about 10 mA/cm.sup.2 to about 45 mA/cm.sup.2, about 20 mA/cm.sup.2 to about 40 mA/cm.sup.2, or any range or value therein.
[0124] Referring still to
[0125] In some embodiments, a CERC according to the present disclosure includes the following features: [0126] a stainless steel (SS304) cathode rotary drum, for which the rotation direction may be clockwise or counterclockwise; [0127] electrodeposition of the metal product occurs primarily on the lower half of the cathode (or working electrode) where the drum is immersed in the electrolyte with close proximity (e.g., having a 10-15 mm gap) relative to the anode (or counter electrode), which may exhibit a corresponding oxide or gas evolution reaction based on operating parameters; [0128] freshly extracted electrodeposited metal product leaves the bath and is carried past a heated air knife to mitigate electrolyte drag-out and enable easier product removal (described in next step below); [0129] metal product adhering to the surface of the drum is then carried around to the scraping member, where an angled knife edge removes the metal product and delivers it to a collector bin/system; [0130] an electroplating rectifier supplies precise and uniformly distributed electrical potential (up to 12 volts) between the cathode and the anode (not shown).
[0131] Alternative configurations and operating parameters are also possible.
[0132] In some embodiments, the molten salt electrolyte comprises one or more of LiOH, NaOH, KOH, and CsOH. In some embodiments, the electrolyte bath further comprises a feedstock comprising a first metal, wherein the first metal is in an average oxidation state of +3 or less, +2 or less, or +1 or less, in the feedstock.
[0133] In some embodiments, the method comprises electrochemical reduction from metal oxides and/or chalcogenides. Such embodiments enable recovery of metals from sulfur-containing ores, compounds and minerals in low concentrations or via processing of low-grade ores or dilute waste streams.
[0134] Thus, in another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a method for electrodeposition of a first metal onto an electrode from a feedstock comprising the first metal, the method comprising: [0135] providing the feedstock to a molten salt electrolyte, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock; [0136] contacting a working electrode and a counter electrode with the molten salt electrolyte comprising the feedstock; and [0137] applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, [0138] wherein: [0139] the working electrode comprises a rotary drum having a central axis and a lateral surface, wherein the rotary drum rotates about the central axis while the voltage is applied; and [0140] at least a portion of the lateral surface is submerged in the molten salt electrolyte while the rotary drum is rotated about the central axis.
[0141] Referring to
[0142] Thus in another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a method of separating a metal from a feedstock, the method comprising: [0143] (a) solubilizing a first metal from the feedstock to obtain a metal composition, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock; and [0144] (b) electrodepositing the first metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0145] providing the metal composition to a molten salt electrolyte comprising hydroxide-containing salts; [0146] contacting a working electrode and a counter electrode with the molten salt electrolyte; and [0147] applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, [0148] wherein: [0149] the working electrode comprises a rotary drum having a central axis and a lateral surface, wherein the rotary drum is rotated about the central axis; and [0150] at least a portion of the lateral surface is submerged in the molten salt electrolyte while the rotary drum is rotated about the central axis.
[0151] In some embodiments, the working electrode comprises a cathode electrode material comprising any one or more of the following: carbon, or a metal rod or foil composed of Pt, Ni, Co, Cu, Al or stainless steel (SS 304/316 grades).
[0152] In some embodiments, the continuous electrodeposition apparatus comprises a heater configured to heat the molten salt electrolyte in the molten electrolyte bath to a temperature that is between 170 C. and 370 C., between 200 C. and 350 C., or between 250 C. and 270 C.
[0153] In some embodiments, the voltage supply is configured to supply a voltage that provides a current density of the process that may range from 1-50 mA/cm.sup.2, and preferably from 5-25 mA/cm.sup.2, and most preferably from 25-50 mA/cm.sup.2.
Metals for Refinement and Feedstocks Comprising the Same
[0154] According to certain aspects, a molten salt electrolytic process may be capable of extracting certain alkali metals, alkaline earth metals, transition metals, including rare earth metals present in the form of oxides, hydroxides, oxyhydroxides, or sulfides. A molten salt electrolysis process is different from, e.g., metallothermic methods, because metallothermic methods are determined by standard free energy formation, melting point, boiling point, vapor pressure, viscosity, and density. In contrast, in the case of molten salt electrolysis, in addition to these factors just mentioned, a decomposition potential can also be involved and utilized (i.e., applied voltage). Furthermore, according to certain aspects, molten salts or fused salts are more advantageous than water as an electrolyte or solvent, because of their high chemical stability, excellent electrical conductivity, high reaction rate, broad temperature range of operation, low vapor pressure, and good heat capacity (or other thermal properties).
[0155] In some embodiments, the one or more metals may be extracted from feedstocks containing transition metals (e.g., Co, Cu, Ga, Mn, Pb, Zn Al, V, Cr, Sc, Ti, Cr, Fe, Ni, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ag, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, etc.), and introduced into the molten electrolyte salt bath as transition metal oxides and hydroxides (e.g., Co(OH).sub.2, Cu(OH).sub.2, GaO, MnO.sub.2, PbO, ZnO, AlO.sub.x, V.sub.2O.sub.5, Cr.sub.2O.sub.3, etc.), or transition metal chalcogenides (such as transition metal sulfides, e.g., CoS, NiS, PbS, CuFeS.sub.2, MoS.sub.2, etc.). In some embodiments, the first metal is selected from the group consisting of: Al, Sb, Be, Cd, Cr, Co, Cu, In Fe, Ga, Pb, Li, Mn, Mg, Mo, Nd, Ni, Pd, Pt, Na, Ag, Sr, Sn, W, and Zn. In some embodiments, the first metal is selected from Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd. In some embodiments, the first metal has an average oxidation state of 1+ to 4+ in the feedstock.
[0156] In some embodiments, the one or more metals may be extracted from feedstocks comprising an alkali metal (Li, Na, K, Rb, Cs, or any combination thereof). In some embodiments, the one or more alkali metals may be extracted from alkali metal feedstocks where the metal is in the +1 oxidation state such as a hydroxide (LiOH, NaOH, KOH, RbOH, CsOH, etc.), an alkali metal oxide (e.g., Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, Cs.sub.2O, Na.sub.2O.sub.2, K.sub.2O.sub.2, Rb.sub.2O.sub.2, Cs.sub.2O.sub.2, KO.sub.2, RbO.sub.2, CsO.sub.2, etc.), an alkali metal chalcogenide (e.g., Li.sub.2S, Na.sub.2S, K.sub.2S, Rb.sub.2S, Cs.sub.2S, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0157] In some embodiments, the one or more metals may be extracted from feedstocks comprising an alkaline earth metal (Be, Mg, Ca, Sr, Ba, or any combination thereof). Further, the one or more alkaline earth metals may be extracted from an alkaline earth metal feedstock where the metal is in the +2 oxidation state such as a hydroxide (e.g., Be(OH).sub.2, Mg(OH).sub.2, Ca(OH).sub.2, Sr(OH).sub.2, Ba(OH.sub.2), Ra(OH).sub.2, etc.), alkaline earth metal oxide (e.g., BeO, MgO, CaO, SrO, BaO, RaO, etc.), alkaline earth metal chalcogenide (e.g., MgS, CaS, SrS, BaS, RaS, BeSe, MgSe, CaSe, SrSe, BaSe, RaSe, BeTe, MgTe, CaTe, SrTe, BaTe, RaTe, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0158] In some embodiments, the one or more metals may be extracted from feedstocks comprising a Group 3B transition metal (e.g., Sc, Y, La, Ac, or any combination thereof). In some embodiments, the one or more Group 3B transition metals may be extracted from a hydroxide (e.g., Sc(OH).sub.3, Y(OH).sub.3, La(OH).sub.3, etc.), an oxide (e.g., Sc.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, etc.), or chalcogenide (e.g., Sc.sub.2S.sub.3, Sc.sub.2Se.sub.3, Y.sub.2S.sub.3, Y.sub.sSe.sub.3, La.sub.2S.sub.3, La.sub.2Se.sub.3, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0159] In some embodiments, the one or more metals may be extracted from feedstocks comprising a Group 4B transition metal (e.g., Ti, Zr, Hf, or any combination thereof). In some embodiments, the one or more Group 4B transition metals may be extracted from a hydroxide (e.g., Ti(OH).sub.4, Zr(OH).sub.4, Hf(OH).sub.4, etc.), an oxide (e.g., TiO.sub.2, ZrO.sub.2, HfO.sub.2, etc.), or chalcogenide (e.g., TiS.sub.2, TiSe.sub.2, TiTe.sub.2, ZrS.sub.2, ZrSe.sub.2, ZrTe.sub.2, ZrSeS, HfS.sub.2, HfSe.sub.2, HfTe.sub.2, etc.) a nitrate, a sulfate, a halide, or any combination thereof.
[0160] In some embodiments, the one or more metals may be extracted from feedstocks comprising a Group 5B transition metal (e.g., V, Nb, Ta, or any combination thereof). In some embodiments, the one or more Group 5B transition metals may be extracted from a hydroxide (e.g., V(OH).sub.2, V(OH).sub.3, VO(OH).sub.2, V(OH).sub.5, Nb(OH).sub.5, Ta(OH).sub.5, etc.), an oxide (e.g., V.sub.2O.sub.5, VO, VO.sub.2, VO.sub.3, Nb.sub.2O.sub.5, Ta.sub.2O.sub.5, etc.), or chalcogenide (e.g., VS.sub.2, VSe.sub.2, VTe.sub.2, NbS.sub.2, NbSe.sub.2, NbTe.sub.2, TaS.sub.2, TaSe.sub.2, TaTe.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0161] In some embodiments, the one or more metals may be extracted from feedstocks where one or more transition metals extracted comprise(s) a Group 6B transition metal (e.g., Cr, Mo, W, or any combination thereof). In some embodiments, the one or more Group 6B transition metals may be extracted from a hydroxide (e.g., Cr(OH).sub.2, Cr(OH).sub.3, Mo(OH).sub.4, W(OH).sub.6, etc.), an oxide (e.g., Cr.sub.2O.sub.3, CrO, CrO.sub.3, MoO.sub.2, MoO.sub.3, WO.sub.2, WO.sub.3, etc.), or chalcogenide (e.g., CrS, Cr.sub.2S.sub.3, CrSe.sub.2, CrTe.sub.2, MoS.sub.2, MoSe.sub.2, MoTe.sub.2, WS.sub.2, WSe.sub.2, WTe.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0162] In some embodiments, the one or more metals may be extracted from feedstocks where the extracted metal comprise(s) a Group 7B transition metal (e.g., Mn, Tc, Re, or any combination thereof). In some embodiments, the one or more Group 7B transition metals may be extracted from a hydroxide (e.g., Mn(OH).sub.2, Mn(OH).sub.3, MnO(OH), TcO.sub.2.Math.2H.sub.2O, etc.), an oxide (e.g., MnO, Mn.sub.2O.sub.3, MnO.sub.2, Mn.sub.2O.sub.7, TcO.sub.2, Tc.sub.2O.sub.7, TcO.sub.3, ReO.sub.2, ReO.sub.3, Re.sub.2O.sub.7, etc.), or chalcogenide (e.g., MnS, MnS.sub.2, MnSe, MnTe, TcS.sub.2, TcSe.sub.2, TcTe.sub.2, ReS.sub.2, Re.sub.2S.sub.3, ReSe.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0163] In some embodiments, the one or more metals may be extracted from feedstocks where the metal extracted comprise(s) a Group 8 transition metal (e.g., Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, or any combination thereof). In some embodiments, the one or more transition metals extracted comprise(s) a platinum group metal (PGM) (e.g., Rh, Pd, Os, Ir, Pt, or any combination thereof). In some embodiments, the one or more Group 8 transition metals may be extracted from a hydroxide (e.g., Fe(OH).sub.2, Fe(OH).sub.3, FeO(OH), Co(OH).sub.2, Ni(OH).sub.2, NiO(OH), Ru(OH).sub.3, OsO.sub.4.Math.4H.sub.2O, Rh(OH).sub.3, Ir(OH).sub.3, Pd(OH).sub.2, Pt(OH).sub.4, etc.), an oxide (e.g., FeO, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, Co.sub.2O.sub.3, Co.sub.3O.sub.4, NiO, RuO.sub.2, RuO.sub.4, OsO.sub.2, Rh.sub.2O.sub.3, RhO.sub.2, IrO.sub.2, IrO.sub.3, PdO, PdO.sub.2, PtO, PtO.sub.2 etc.), or chalcogenide (e.g., FeS, FeS.sub.2, FeSe, FeTe, CoS.sub.2, Co.sub.3S.sub.4, CoSe, CoSe.sub.2, CoTe, CoTe.sub.2, RuS.sub.2, RuSe.sub.2, RuTe.sub.2, OsS.sub.2, OsSe.sub.2, OsTe.sub.2, Rh.sub.2S.sub.3, RhSe.sub.2, RhTe.sub.2, IrS.sub.2, IrSe.sub.2, IrTe.sub.2, PdS, PdSe.sub.2, PdTe.sub.3, PtS, PtS.sub.2, PtSe.sub.2, PtTe.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0164] In some embodiments, the one or more metals may be extracted from feedstocks where the transition metals extracted comprise(s) a Group 1B transition metal (precious metal) (e.g., Au, Ag, Cu, or any combination thereof). In some embodiments, the one or more Group 1B transition metals may be extracted from a hydroxide (e.g., CuOH, Cu(OH).sub.2, AgOH, AuOH, Au(OH).sub.3, etc.), an oxide (e.g., CuO, Cu.sub.2O, AgO, Ag.sub.2O, etc.), or chalcogenide (e.g., CuS, Cu.sub.2S, CuSe, Cu.sub.2Se, CuTe, Cu.sub.2Te, Ag.sub.2S, Ag.sub.2Se, Ag.sub.2Te, Au.sub.2S, Au.sub.2S.sub.3, Au.sub.2Se, Au.sub.2Te, AuTe.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0165] In some embodiments, the one or more metals may be extracted from feedstocks where the metals extracted comprise(s) a Group 2B transition metal (e.g., Zn, Cd, Hg, or any combination thereof). In some embodiments, the one or more Group 2B transition metals may be extracted from a hydroxide (e.g., Zn(OH).sub.2, Cd(OH).sub.2, Hg(OH).sub.2, etc.), an oxide (e.g., ZnO, CdO, HgO, Hg.sub.2O, etc.), or chalcogenide (e.g., ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0166] In some embodiments, the one or more metals may be extracted from feedstocks where the metals extracted comprise(s) a post-transition metal (e.g., Al, Ga, In, Sn, Tl, Pb, Bi, Po, or any combination thereof). In some embodiments, the one or more post-transition metals may be extracted from a hydroxide (e.g., Al(OH).sub.3, Ga(OH).sub.3, In(OH).sub.3, InOH, Sn(OH).sub.2, Sn(OH).sub.4, TlOH, Tl(OH).sub.3, Pb(OH).sub.2, Bi(OH).sub.3, BiO(OH), etc.), an oxide (e.g., Al.sub.2O.sub.3, Ga.sub.2O.sub.3, In.sub.2O.sub.3, In.sub.2O, SnO, SnO.sub.2, Tl.sub.2O, Tl.sub.2O.sub.3, PbO, PbO.sub.2, Bi.sub.2O.sub.3, Bi.sub.2O.sub.5, PoO.sub.2, etc.), or chalcogenide (e.g., Al.sub.2S.sub.3, Al.sub.2Se.sub.3, Al.sub.2Te.sub.3, Ga.sub.2S.sub.3, In.sub.2S.sub.3, SnS, SnS.sub.2, SnSe, SnSe.sub.2, SnTe, Tl.sub.2S, Tl.sub.2Se, Tl.sub.2Te, PbS, PbSe, PbTe, Bi.sub.2S.sub.3, Bi.sub.2Se.sub.3, Bi.sub.2Te.sub.3, PoS, PoSe, PoTe, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0167] In some embodiments, the one or more metals may be extracted from feedstocks where the metals extracted comprise(s) a semi-metal (metalloid) (e.g., B, Si, Ge, As, Sb, Te, or any combination thereof). In some embodiments, the one or more semi-metals may be extracted from a hydroxide (e.g., As(OH).sub.3, As(OH).sub.5, Sb(OH).sub.3), Sb(OH).sub.5, H.sub.6TeO.sub.6 etc.), an oxide (e.g., B.sub.2O.sub.3, SiO.sub.2, GeO.sub.2, As.sub.2O.sub.3, As.sub.2O.sub.5, Sb.sub.2O.sub.3, Sb.sub.2O.sub.5, TeO.sub.2, TeO.sub.3, etc.), or chalcogenide (e.g., B.sub.2S.sub.3, B.sub.2Se.sub.3, B.sub.2Te.sub.3, SiS.sub.2, SiSe.sub.2, SiTe.sub.2, GeS, GeS.sub.2, GeSe, GeSe.sub.2, GETe, As.sub.2S.sub.3, As.sub.2S.sub.5, As.sub.2Se.sub.3, As.sub.2Te.sub.3, TeS, TeS.sub.2, etc.), a nitrate, a sulfate, a halide, or any combination thereof.
[0168] In some embodiments, the one or more metals may be extracted from feedstocks where the metals extracted comprise(s) a lanthanide (rare earth metal) (e.g., La, Ce, Pr, Nd, Sm, Eu, Dg, Tb, Dy, Ho, Er, Yb) or actinide (e.g., Th, U, Np, Pu, etc.). In some embodiments, the one or more lanthanides or actinides may be extracted from a hydroxide, oxide, sulfide, selenide, telluride, halide, nitrate, sulfate, or any combination thereof.
[0169] In some embodiments, the one or more metals may be extracted from feedstocks belonging to the one or more of the group of transition metals, alkali metals, alkaline earth metals, post-transition metals, semi-metals, lanthanides, or actinides may be extracted from a salt or alloy of any of the above metals or metal compounds.
[0170] In some embodiments, the one or more metals comprises at least one selected from the group consisting of Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr, Nd, Li, Be, Na, Si, Ti, V, W, Pd, Au, Ge, As, In, Hg, Sm, and Bi. In some embodiments, the one or more metals comprises at least one selected from the group consisting of Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd. In some embodiments, the metal comprises Mg. In some embodiments, the metal comprises Co. In some embodiments, the metal comprises Ni. In some embodiments, the metal comprises Ag. In some embodiments, the metal comprises Cu. In some embodiments, the metal comprises Cr. In some embodiments, the metal comprises Zn. In some embodiments, the metal comprises Ga. In some embodiments, the metal comprises Sn. In some embodiments, the metal comprises Al. In some embodiments, the metal comprises Sb. In some embodiments, the metal comprises Pb. In some embodiments, the metal comprises Fe. In some embodiments, the metal comprises Cd. In some embodiments, the metal comprises Mn. In some embodiments, the metal comprises Pt. In some embodiments, the metal comprises Sr. In some embodiments, the metal comprises Nd. In some embodiments, the metal comprises Li. In some embodiments, the metal comprises Be. In some embodiments, the metal comprises Na. In some embodiments, the metal comprises Si. In some embodiments, the metal comprises Ti. In some embodiments, the metal comprises V. In some embodiments, the metal comprises W. In some embodiments, the metal comprises Pd. In some embodiments, the metal comprises Au. In some embodiments, the metal comprises Ge. In some embodiments, the metal comprises As. In some embodiments, the metal comprises In. In some embodiments, the metal comprises Hg. In some embodiments, the metal comprises Sm. In some embodiments, the metal comprises Bi.
[0171] In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Co, Cu, and Ni. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Pb, Zn, and Co. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Ga and Zn. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Ag, Zn, and Pb. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Ga, Sn, and Al. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising mixed alkali silicates. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Mg and Fe. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Pb and Sb. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Ag and Cu. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising Pb and Sb. In some embodiments, the one or more metals comprises at least one element selected from feedstocks containing more than one element, such as feedstocks comprising scrap metal with various amounts of Cu, Ni, Fe, Mn, and/or Mo.
[0172] In some embodiments, the one or more metals (which may be any of the metals discussed above) has an average oxidation state in the feedstock of 4+ or less, 3+ or less, 2.5+ or less, 2+ or less, 1.5+ or less, or 1+ or less. For instance, in some embodiments, the one or more metals is Ga and has an average oxidation state of 3+ in the feed stock. In some embodiments, the one or more metals is Co and has an average oxidation state of 2+ in the feedstock. For purposes of the present disclosure, the average oxidation state (or average oxidation number) of a metal in a feedstock refers to the mean or effective oxidation state of that metal, calculated based on its oxidation states across all atoms of the metal in the feedstock.
[0173] In some embodiments, the electrodeposition comprises reducing the average oxidation state of one or more metals in the feedstock from a higher average oxidation state (e.g., 2+, 2.5+, 3+, 3.5+, 4+, 4.5+, 5+, 5.5+, 6+, 6.5+, or 7+) to a lower average oxidation state (e.g., 0, 1+, 1.5+, 2+, 2.5+, 3+, or 4+). In some embodiments, the electrodeposition comprises reducing the average oxidation state of one or more metals from a higher average oxidation state (e.g., in the range of 1+ to +4) to a lower average oxidation state (e.g., in the range of 0 to 2+). In some embodiments, the electrodeposition comprises reducing the average oxidation state of one or more metals to 0, such that the electrodeposited metal is in elemental form. In some embodiments, the electrodeposition comprises reducing the average oxidation state of one or more metals to a value above 0, such as 1+, 1.5+, or 2+, such that the electrodeposited metal is in the form of a compound, such as an oxide, hydroxide, oxyhydroxide, or sulfide.
[0174] The metal compounds containing metals to be extracted via methods of the present disclosure may be derived from one or more sources, including but not limited to mine tailings, metal waste piles, recycle streams, and low grade ores, among other potential sources. In some embodiments, the feedstock comprises one or more alloys, ores, concentrates, mine wastes, or tailings. Referring to
[0175] In some embodiments, e.g., where the metal(s) to be extracted are present in scrap or alloys, the metal may be present in the feedstock with an average oxidation state of 0.
[0176] For purposes of the present disclosure, the term oxidizing voltage refers to an electrode potential high enough to drive oxidation reactionsthat is, an electrode potential at which oxidation (removal of electrons from a species) occurs. For purposes of the present disclosure, the term reducing voltage refers to an electrode potential sufficient to drive a reduction reactionthat is, an electrode potential at which reduction (addition of electrons to a species) occurs.
Molten Salt Electrolytes
[0177] According to aspects described herein, some key advantages of molten salt electrochemistry aided extraction and/or separation are as follows: although single salts may be used, mixtures of molten salts can help reduce the melting point (by forming eutectics) by several hundred degrees. Unlike metallothermic processes, the electrolysis process can run continuously in a high volume of production, as well as continuous production, making it effective for scaling to large plants. Furthermore, unlike metallothermic process, the molten salt process is more straightforward in reducing the requirements for feedstock preparation by selection of specific molten salts which provide for high feedstock solubility.
[0178] In some embodiments, the molten salt electrolyte comprises alkali hydroxides. For example, in some embodiments, the molten salt electrolyte comprising any one of the following compounds: LiOH, KOH, NaOH or CsOH, in the fully molten state. In some embodiments, the molten salt electrolyte comprises halide, sulfate, carbonate, borate, or nitrate molten salts.
[0179] In some embodiments, the molten salt electrolyte comprises a binary molten salt system of type Salt1Salt2 where the mol. % of the mixture Salt1+Salt2=100% by weight of the total molten salt. In some embodiments, the mixture Salt1Salt2 is any one or more of the following: LiOHKOH, LiOHNaOH, LiOHCsOH, KOHNaOH, KOHCsOH, and NaOHCsOH. In some embodiments, in the binary molten salt system the mole percentage of Salt 1 in the mixture may vary from 1-100% and the mole percentage of Salt 2 is 100% Salt 1.
[0180] In some embodiments, in a binary molten salt system, any of the Salt 1, the Salt 2, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of at least about 0.01, at least about 0.02, at least about 0.03, at least about 0.04, at least about 0.05, at least about 0.10, at least about 0.15, at least about 0.20, at least about 0.25, at least about 0.30, at least about 0.35, at least about 0.40, at least about 0.45, at least about 0.50, at least about 0.55, at least about 0.60, at least about 0.65, at least about 0.70, at least about 0.75, at least about 0.80, at least about 0.85, at least about 0.90, at least about 0.95, at least about 0.96, at least about 0.97, at least about 0.98, at least about 0.99, or any range or value including and/or in between any two of these values.
[0181] In some embodiments, in a binary molten salt system, any of the Salt 1, the Salt 2, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of less than or equal to about 0.99, less than or equal to about 0.98, less than or equal to about 0.97, less than or equal to about 0.96, less than or equal to about 0.95, less than or equal to about 0.90, less than or equal to about 0.85, less than or equal to about 0.80, less than or equal to about 0.75, less than or equal to about 0.70, less than or equal to about 0.65, less than or equal to about 0.60, less than or equal to about 0.55, less than or equal to about 0.50, less than or equal to about 0.45, less than or equal to about 0.40, less than or equal to about 0.35, less than or equal to about 0.30, less than or equal to about 0.25, less than or equal to about 0.20, less than or equal to about 0.15, less than or equal to about 0.10, less than or equal to about 0.05, less than or equal to about 0.04, less than or equal to about 0.03, less than or equal to about 0.02, less than or equal to about 0.01, or any range or value including and/or in between any two of these values.
[0182] In some embodiments, in a binary molten salt system, any of the Salt 1, the Salt 2, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of about 0.01 to about 0.99, about 0.02 to about 0.98, about 0.03 to about 0.97, about 0.04 to about 0.96, about 0.05 to about 0.95, about 0.10 to about 0.90, about 0.20 to about 0.80, about 0.30 to about 0.70, about 0.40 to about 0.60, about 0.05 to about 0.15, about 0.10 to about 0.20, about 0.15 to about 0.25, about 0.20 to about 0.30, about 0.25 to about 0.35, about 0.30 to about 0.40, about 0.35 to about 0.45, about 0.40 to about 0.50, about 0.45 to about 0.55, about 0.50 to about 0.60, about 0.55 to about 0.65, about 0.60 to about 0.70, about 0.65 to about 0.75, about 0.70 to about 0.80, about 0.75 to about 0.85, about 0.80 to about 0.90, about 0.85 to about 0.95, or about 0.90 to about 0.99, or any range or value therein.
[0183] In some embodiments, the molten salt electrolyte comprises a ternary molten salt system of type Salt1Salt2Salt3 where the mol. % of Salt1+Salt2+Salt3=100% by weight of the total molten salt. In some embodiments, the ternary salt mixture may further be any one or more of LiOHKOHNaOH, LiOHKOHCsOH, KOHNaOHCsOH, and LiOHNaOHCsOH. In some embodiments, the mole percentage of Salt 1 and Salt 2 in the mixture may vary from 1-100% and the mole percentage of Salt 3 is [100(% Salt 1+% Salt2)].
[0184] In some embodiments, in a ternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of at least about 0.01, at least about 0.02, at least about 0.03, at least about 0.04, at least about 0.05, at least about 0.10, at least about 0.15, at least about 0.20, at least about 0.25, at least about 0.30, at least about 0.35, at least about 0.40, at least about 0.45, at least about 0.50, at least about 0.55, at least about 0.60, at least about 0.65, at least about 0.70, at least about 0.75, at least about 0.80, at least about 0.85, at least about 0.90, at least about 0.95, at least about 0.96, at least about 0.97, at least about 0.98, at least about 0.99, or any range or value including and/or in between any two of these values.
[0185] In some embodiments, in a ternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of less than or equal to about 0.99, less than or equal to about 0.98, less than or equal to about 0.97, less than or equal to about 0.96, less than or equal to about 0.95, less than or equal to about 0.90, less than or equal to about 0.85, less than or equal to about 0.80, less than or equal to about 0.75, less than or equal to about 0.70, less than or equal to about 0.65, less than or equal to about 0.60, less than or equal to about 0.55, less than or equal to about 0.50, less than or equal to about 0.45, less than or equal to about 0.40, less than or equal to about 0.35, less than or equal to about 0.30, less than or equal to about 0.25, less than or equal to about 0.20, less than or equal to about 0.15, less than or equal to about 0.10, less than or equal to about 0.05, less than or equal to about 0.04, less than or equal to about 0.03, less than or equal to about 0.02, less than or equal to about 0.01, or any range or value including and/or in between any two of these values.
[0186] In some embodiments, in a ternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of about 0.01 to about 0.99, about 0.02 to about 0.98, about 0.03 to about 0.97, about 0.04 to about 0.96, about 0.05 to about 0.95, about 0.10 to about 0.90, about 0.20 to about 0.80, about 0.30 to about 0.70, about 0.40 to about 0.60, about 0.05 to about 0.15, about 0.10 to about 0.20, about 0.15 to about 0.25, about 0.20 to about 0.30, about 0.25 to about 0.35, about 0.30 to about 0.40, about 0.35 to about 0.45, about 0.40 to about 0.50, about 0.45 to about 0.55, about 0.50 to about 0.60, about 0.55 to about 0.65, about 0.60 to about 0.70, about 0.65 to about 0.75, about 0.70 to about 0.80, about 0.75 to about 0.85, about 0.80 to about 0.90, about 0.85 to about 0.95, or about 0.90 to about 0.99, or any range or value therein.
[0187] In some embodiments, the molten salt electrolyte comprises a quaternary molten salt system wherein the mol. % of Salt1+Salt2+Salt3+Salt4=100% of the total molten salt. In some embodiments, the quaternary molten salt system is LiOHKOHNaOHCsOH.
[0188] In some embodiments, the molten salt electrolyte comprises a quaternary salt LiOHKOHNaOHCsOH where the mol. % of Salt1+Salt2+Salt3+Salt4=100% of the total molten salt.
[0189] In some embodiments, in a quaternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, the Salt 4, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of at least about 0.01, at least about 0.02, at least about 0.03, at least about 0.04, at least about 0.05, at least about 0.10, at least about 0.15, at least about 0.20, at least about 0.25, at least about 0.30, at least about 0.35, at least about 0.40, at least about 0.45, at least about 0.50, at least about 0.55, at least about 0.60, at least about 0.65, at least about 0.70, at least about 0.75, at least about 0.80, at least about 0.85, at least about 0.90, at least about 0.95, at least about 0.96, at least about 0.97, at least about 0.98, at least about 0.99, or any range or value including and/or in between any two of these values.
[0190] In some embodiments, in a quaternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, the Salt 4, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of less than or equal to about 0.99, less than or equal to about 0.98, less than or equal to about 0.97, less than or equal to about 0.96, less than or equal to about 0.95, less than or equal to about 0.90, less than or equal to about 0.85, less than or equal to about 0.80, less than or equal to about 0.75, less than or equal to about 0.70, less than or equal to about 0.65, less than or equal to about 0.60, less than or equal to about 0.55, less than or equal to about 0.50, less than or equal to about 0.45, less than or equal to about 0.40, less than or equal to about 0.35, less than or equal to about 0.30, less than or equal to about 0.25, less than or equal to about 0.20, less than or equal to about 0.15, less than or equal to about 0.10, less than or equal to about 0.05, less than or equal to about 0.04, less than or equal to about 0.03, less than or equal to about 0.02, less than or equal to about 0.01, or any range or value including and/or in between any two of these values.
[0191] In some embodiments, in a quaternary molten salt system, any of the Salt 1, the Salt 2, the Salt 3, the Salt 4, or the metal compound(s) present in the molten salt electrolyte may be present at a mass fraction, relative to the total mass of the molten salt electrolyte mixture (including any metal compounds), of about 0.01 to about 0.99, about 0.02 to about 0.98, about 0.03 to about 0.97, about 0.04 to about 0.96, about 0.05 to about 0.95, about 0.10 to about 0.90, about 0.20 to about 0.80, about 0.30 to about 0.70, about 0.40 to about 0.60, about 0.05 to about 0.15, about 0.10 to about 0.20, about 0.15 to about 0.25, about 0.20 to about 0.30, about 0.25 to about 0.35, about 0.30 to about 0.40, about 0.35 to about 0.45, about 0.40 to about 0.50, about 0.45 to about 0.55, about 0.50 to about 0.60, about 0.55 to about 0.65, about 0.60 to about 0.70, about 0.65 to about 0.75, about 0.70 to about 0.80, about 0.75 to about 0.85, about 0.80 to about 0.90, about 0.85 to about 0.95, or about 0.90 to about 0.99, or any range or value therein.
[0192] In some embodiments, the temperature of the molten salt electrolyte is between 170 C. and 370 C., between 200 C. and 350 C., or between 250 C. and 270 C.
Electrodeposited Material
[0193] Methods according to the present disclosure afford a continuous route to industrial-scale production of high-purity electrodeposited material. In some embodiments, the electrodeposited material may comprise an elemental metal. In some embodiments, the electrodeposited material may comprise an alloy comprising two or more metals. In some embodiments, the electrodeposited material may comprise a metal-containing compound (e.g., an oxide, hydroxide, oxyhydroxide, or sulfide). In some embodiments, the electrodeposited material may comprise a powder or foil.
[0194] In some embodiments, the purity of the electrodeposited material, as determined by energy dispersive x-ray spectroscopy (EDX) or inductively coupled plasma (ICP) optical emission spectroscopy (ICP-OES). In some embodiments, the electrodeposited metal has a purity of at least 85 at. %, at least 90 at. %, at least 91 at. %, at least 92 at. %, at least 93 at. %, at least 94 at. %, at least 95 at. %, at least 96 at. %, at least 97 at. %, at least 98 at. %, at least 99 at. %, at least 99.5 at. %, at least 99.6 at. %, at least 99.7 at. %, at least 99.8 at. %, at least 99.9 at. %, range or value including and/or in between any two of these values.
Methods of Separating or Recycling Metals from Feedstocks
[0195] In another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to methods of recycling or separating metals from feedstocks. In some embodiments, the feedstocks may comprise alloys, mine tailings, ores, electronic waste, scrap, or any combination thereof. Thus, separation methods disclosed herein may be useful in the context of recycling metals from electronic waste or scrap, which may comprise alloys or elemental metals.
[0196] As used herein, the term recycle or recycling refers to converting discarded or secondary metal-bearing materialssuch as scrap, electronic waste, used, end-of-life, or spent batteries, used or end-of-life magnets, or industrial residuesinto high-purity metal products by chemically or electrochemically dissolving the metal content into an electrolyte and selectively electrodepositing the target metal(s) onto electrodes, thereby enabling return of the recovered metal to the manufacturing supply chain.
[0197] In some embodiments, methods of recycling or separating a metal from a feedstock comprise: (a) solubilizing a metal from the feedstock to obtain a metal composition; and (b) electrodepositing the metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0198] providing the metal composition to a molten salt electrolyte; [0199] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0200] applying a first voltage to the working electrode and counter-electrode that is sufficient to electrodeposit a first metal in elemental form, from the feedstock onto the working electrode.
[0201] In some embodiments, methods of recycling or separating a metal from a feedstock comprise: (a) solubilizing a metal from the feedstock to obtain a metal composition; and (b) electrodepositing the metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0202] providing the metal composition to a molten salt electrolyte; [0203] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0204] applying a voltage to the electrodes that is sufficient to electrodeposit the metal from the molten salt electrolyte onto the working electrode in elemental form, [0205] wherein: [0206] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0207] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0208] In some embodiments, the solubilizing in (a) is carried out by way of, e.g., acid leaching (e.g., using HCl, H.sub.2SO.sub.4, HNO.sub.3, aqua regia, etc.), cyanide leaching (e.g., using NaCN or KCN in basic conditions), thiourea or thiosulfate leaching, ammoniacal leaching, chlorine gas or chloride leaching (e.g., using NaCl or CaCl.sub.2 and oxidants), ionic liquid leaching (e.g., using imidazolium salts), microbial leaching (e.g., using A. ferrooxidans, A. thiooxidans, L. ferrooxidans, S. thermosulidooxidans, F. acidarmanus, M. sedula, etc.).
[0209] The electrodepositing (b) may be performed using any of the methods of the present disclosure, as discussed herein.
[0210] In some embodiments, the recycling comprises purifying a metal (e.g., lead, samarium, neodymium or) from a previously used article (e.g., a used, spent, or end-of-life lead acid battery (LAB), a magnet, etc.). Thus, in some embodiments, the metal is recycled from a feedstock comprising a LAB or LAB component (e.g., one or more of a LAB anode, LAB cathode, LAB separator, or LAB electrolyte). In some embodiments, the metal is recycled from a magnet of the NdFeB or SmCo types.
[0211] In some embodiments, the present disclosure relates to a method of recycling lead from a feedstock, the method comprising: (a) solubilizing lead from the feedstock to obtain a lead composition; and (b) electrodepositing the lead in elemental form onto an electrode from the lead composition, the electrodepositing comprising: [0212] providing the lead composition to a molten salt electrolyte; [0213] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0214] applying a voltage to the electrodes that is sufficient to electrodeposit the lead from the molten salt electrolyte onto the working electrode in elemental form, [0215] wherein: [0216] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0217] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0218] In some embodiments, the feedstock comprises a lead-acid battery (LAB). In some embodiments, the feedstock comprises a component of a LAB, such a LAB cathode, a LAB anode, a LAB separator, or LAB electrolyte.
[0219] For instance, in some embodiments, the present disclosure relates to a method of recycling a metal from a feedstock, the method comprising: (a) solubilizing the metal from the feedstock to obtain a metal composition; and (b) electrodepositing the metal in elemental form onto an electrode from the lead composition, the electrodepositing comprising: [0220] providing the metal composition to a molten salt electrolyte; [0221] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0222] applying a voltage to the electrodes that is sufficient to electrodeposit the metal from the molten salt electrolyte onto the working electrode in elemental form, [0223] wherein: [0224] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0225] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0226] In some embodiments the metal is one or more of Nd, Sm, or Co. In some embodiments, the feedstock is a magnet comprising Sm, Co, Nd, Fe, B, or any combination thereof. In some embodiments, the feedstock is a NdFeB magnet. In some embodiments, the feedstock is a SmCo magnet.
Exemplary Use Case: Demonstration-Scale Electrorefinement of Cobalt and/or Copper
[0227] Accordingly, one aspect of the present disclosure is directed to a method for electrodeposition of elemental cobalt onto an electrode from a cobalt-containing ore or feedstock. In some embodiments, the method comprises: providing the cobalt-containing feedstock or ore, such as mine waste deposits or tailings, to a molten salt electrolyte (e.g., comprising hydroxide-containing salts); immersing a working electrode and a counter-electrode into the molten salt electrolyte; and applying a voltage to the electrodes that is sufficient to electrodeposit cobalt from the cobalt containing feedstock or ore or mine waste deposits or tailings onto the working electrode in elemental form. In some embodiments, the method further comprises immersing a third electrode (e.g., a reference electrode) into the molten salt electrolyte to ascertain the true thermodynamic potentials of the working and counter electrode.
[0228] In some embodiments, the working electrode is a cathode, and the cobalt is electrodeposited by reduction from a Co(II) oxidation form present in the cobalt-containing ore or feedstock onto the working electrode.
[0229] In some embodiments, the cobalt-containing ore or feedstock is obtained from a feedstock containing from 10% to 50% by weight of cobalt-containing compounds. In some embodiments, the cobalt-containing ore or feedstock comprises cobalt in the form of any one or more of Co(OH).sub.2, CoSO.sub.4, CoCl.sub.2, Co(NO.sub.3).sub.2. In some embodiments, the cobalt-containing ore or feedstock comprises impurities selected from the group consisting of any of nickel-containing, manganese-containing, or copper-containing compounds. In some embodiments, the cobalt-containing ore is from feedstock comprising less than 10% by weight of copper-containing compounds, such as 1% by weight or less of copper-containing compounds.
[0230] In some embodiments, the method comprises: applying a first voltage to the electrodes sufficient to electrodeposit copper from the cobalt-containing ore or feedstock onto the working electrode in elemental form, and applying a second voltage that is more negative than the first voltage and that is sufficient to electrodeposit cobalt from the cobalt-containing ore or feedstock onto the working electrode in elemental form.
[0231] In some embodiments, the second voltage is at least 100 mV more negative than the first voltage, but the first voltage and second voltage may be separated by as little as 10 mV difference.
[0232] In some embodiments, the copper that is electrodeposited in elemental form is removed from the working electrode before application of the second voltage to electrodeposit cobalt from the cobalt-containing ore or feedstock. In some embodiments, the first metal (copper) is removed from the working electrode (e.g., a lateral surface of a rotary drum electrode) using a scraping member (see
[0233] In some embodiments, the voltage is applied in the form of a steady state voltage. In some embodiments, the voltage is applied in the form of a pulsed wave, or a series or plurality of pulsed waves.
[0234] In some embodiments, the molten salt electrolyte is circulated via forced flow past the working electrode during application of the voltage to the electrodes.
[0235] Although the continuous electrodeposition apparatus disclosed above is preferred for achieving electrodeposition of cobalt and/or copper from a feedstock comprising these two metals, other electrodeposition cells may be used. Referring to
[0236] In some embodiments, the method comprises utilizing a plurality of working electrodes and/or counter-electrodes that are high surface area electrodes. In some embodiments, the plurality of working electrodes and/or counter-electrodes comprise a combination of electrodes in the form of a plurality of cylinders, and rectangularly shaped electrodes. In some embodiments, the plurality of working electrodes comprises electrodes in the form of a plurality of cylinders, and the plurality of counter electrodes comprise rectangularly shaped electrodes or electrodes in the form of a mesh to increase the surface area of the counter electrodes relative to the working electrode. Other combinations can also be provided.
[0237] In some embodiments, a flow of molten salt electrolyte is circulated past the working electrode by a pump capable of inducing a flow of the molten salt electrolyte in a bath in which the molten salt electrolyte is contained.
[0238] In some embodiments, the current density of the process may range from 1-50 mA/cm.sup.2, and preferably from 5-25 mA/cm.sup.2, and most preferably from 25-50 mA/cm.sup.2.
[0239] In some embodiments, the electrodeposit on the working electrode is cobalt metal or copper metal, and the Co purity or Cu purity so obtained is >98% pure as identified by EDX and/or ICP analysis.
[0240] Thus, another aspect of the present disclosure is directed to an apparatus for electrodeposition of elemental metal onto an electrode from a metal-containing feedstock (e.g., an ore, mine waste, tailings, metal compounds, etc.). The apparatus described herein is a demonstration-scale apparatus for demonstrating electrodeposition conditions appropriate for and transferable to continuous electrodeposition processes.
[0241] As shown in
[0242] In some embodiments, the molten electrolyte circulation system comprises one or more pumps configured to circulate the flow of molten electrolyte past the working electrode in the molten electrolyte bath. In some embodiments, the molten electrolyte circulation system provides a continuous flow of the molten electrolyte across a surface of the working electrode during electrodeposition of the metal.
[0243] In some embodiments, the metal that is electrodeposited is selected from the group consisting of: Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd. In some embodiments, the first metal has an average oxidation state of 4+ or less in the feedstock. In some embodiments, the first metal has an average oxidation state of 1+ to 4+ in the feedstock. In some embodiments, the metal is cobalt metal. In some embodiments, the metal in salt form is provided in the form of a metal-containing ore or feedstock. For instance, in some embodiments, the working electrode is a cathode, the metal is cobalt, and the cobalt is electrodeposited by reduction from a Co(II) oxidation form present in a cobalt-containing ore or feedstock onto the working electrode.
[0244] In some embodiments, the metal-containing ore is provided in the form of a feedstock containing from 10% to 50% by weight of metal-containing compounds. For example, in some embodiments, the metal is cobalt and is present in the form of a cobalt-containing ore or feedstock comprising cobalt in the form of any one or more of Co(OH).sub.2, CoSO.sub.4, CoCl.sub.2, Co(NO.sub.3).sub.2. In some other embodiments, the metal is cobalt and is present in the form of a cobalt-containing ore or feedstock comprising impurities selected from the group consisting of any of nickel-containing, manganese-containing, and copper-containing compounds. In some embodiments, the cobalt-containing ore is provided in the form of a feedstock that comprises less than 10% by weight of copper-containing compounds, or even 1% by weight or less of copper-containing compounds.
[0245] In some embodiments, the voltage supply is configured to: apply a first voltage to the electrodes that is sufficient to electrodeposit a first metal (e.g., copper) from an ore or feedstock comprising a second metal (e.g., Co) onto the working electrode in elemental form, and apply a second voltage that is more negative than the first voltage and that is sufficient to electrodeposit the second metal from the ore or feedstock comprising the second metal onto the working electrode in elemental form. In some embodiments, the second voltage is at least 100 mV more negative than the first voltage, but the first and second voltages may be separated from one another by as little as 10 mV. In some embodiments, a first metal (e.g., Cu) that is electrodeposited in elemental form is removed from the working electrode before application of the second voltage to electrodeposit the second metal (e.g., Co) form the feedstock.
[0246] In some embodiments, the voltage is applied in the form of a steady state voltage. In some embodiments, the voltage is applied in the form of a pulsed wave, or a plurality of pulsed waves.
[0247] In some embodiments, the working electrode is a high surface area electrode. In some embodiments, the working electrode comprises a plurality of cylinders extending into the molten salt electrolyte. In some other embodiments, the working electrode comprises a rectangularly shaped electrode with opposing faces each having a higher surface area than other faces of the working electrode.
[0248] In some embodiments, a flow of the molten salt electrolyte is circulated past the working electrode, and wherein the working electrode comprises a high surface area face that is parallel to a direction of flow of the molten salt electrolyte.
[0249] In some embodiments, the apparatus comprises a plurality of working electrodes and/or counter-electrodes that are high surface area electrodes. For example, in some embodiments, the plurality of working electrodes and/or counter-electrodes comprise a combination of electrodes in the form of a plurality of cylinders and rectangularly shaped electrodes. In some other embodiments, the plurality of working electrodes and plurality of counter electrodes each comprise a plurality of cylinders in alternating rows. In some embodiments, the plurality of working electrodes and plurality of counter electrodes each comprise a plurality of rectangularly shaped electrodes in alternating rows. In some embodiments, the plurality of working electrodes comprises electrodes in the form of a plurality of cylinders, and the plurality of counter electrodes comprise rectangularly shaped electrodes, and wherein the plurality of working electrodes and plurality of counter electrodes are provided in alternating rows.
[0250] In any of the above-discussed embodiments (continuous or demonstration scale), the minimum voltage to be applied across the cell can be identified by acquiring a cyclic voltammogram in the molten salt electrolyte. For example, in order to extract cobalt metal from crude cobalt hydroxide originating from the copper-cobalt mines of the central African copperbelt, the electrolyte can be prepared using a low melting eutectic mixture of NaOHKOH (mol NaOH/(NaOH+KOH)=0.515) as the solvent and adding the crude cobalt hydroxide to this mixture. A cyclic voltammogram obtained from this system, using a platinum working electrode, platinum reference electrode, and nickel counter electrode (
[0251] By way of non-limiting example, operation of a CERC according the present disclosure is described below for the electrorefining of Co metal from Co(OH).sub.2, using an electrolyte prepared using NaOH, KOH, and Co(OH).sub.2, by applying a voltage across the cell using a high current electroplating rectifier. For this exemplary embodiment, the following reactions occur in the CERC:
[0252] For cell voltage between 0.6V to 0.9V, at the cathode, reduction of cobalt metal occurs at a relatively slow rate, with a current density of roughly 20-40 mA/cm.sup.2, leading to the deposition of cobalt in the form of a film.
[0253] The reaction at the cathode proceeds as follows:
##STR00001##
[0254] At the anode, electroplating of cobalt oxides observed and proceeds according to the following equation:
##STR00002##
[0255] This provides an overall reaction represented as follows:
##STR00003##
[0256] In some embodiments, higher cell voltages may be employed to drive formation of gaseous products, rather than solid products, at the anode and reducing material build-up on the anode. This has implications for improving the process and reduces complexity of the equipment and apparatus to be used at full commercial scale. More importantly, cobalt consumption occurs only at the cathode, affording a higher overall process yield because cobalt is not lost by conversion to undesired cobalt oxide.
[0257] For instance, at cell voltage greater than 0.9V, in addition to the reduction of cobalt, hydrogen evolution is observed, according to the following equation:
##STR00004##
[0258] In this cell voltage regime, an oxygen evolution reaction (OER) is observed at the anode, proceeding according to the following equation:
##STR00005##
[0259] As a result, there can be a reduction in the current efficiencies at one or both electrodes.
[0260] In some embodiments, for ideal operation of the CERC to enhance metal extraction from feedstock, it is preferred to produce metal at the cathode and oxygen gas at the anode, such that metal consumption occurs only at the cathode, leading to higher process yield (i.e., reduced loss of metal to undesired oxides). For example, in some embodiments, for ideal operation of the CERC to enhance cobalt extraction from crude Co(OH).sub.2, it is preferred to produce cobalt metal at the cathode and oxygen gas at the anode, such that cobalt consumption occurs only at the cathode, leading to higher process yield (i.e., little or no loss of cobalt to undesired cobalt oxide). Therefore, the CERC may be operated at appropriate cell voltages to enhance metal extraction (e.g., for Co from Co(OH).sub.2 feedstock), one may use cell voltages above 0.9V.
[0261] For example, at small scale, using a three-electrode setup assembled using SS304 foil cathode and anode, it was observed that up to a cell voltage of 2.0V, very little bubbling is observed at the anode. This indicates that OER occurs, but cobalt oxide is still the preferred product. Above 2.0V, a stream of bubbles can be observed, showing that OER becomes the preferred reaction at the anode. At higher voltages up to 4.0V, the intensity of bubbling increases further. However, at this voltage regime, corrosion of the anode substrate (SS304) occurs via oxidation. Thus, by way of non-limiting example, for electrodeposition of Co from Co(OH).sub.2, it is advantageous to operate the CERC at a voltage of between 2.0 V to 4.0 V. One may select appropriate voltages based on the oxidation states and other properties of the metal(s) to be extracted from the feedstock.
[0262] One of ordinary skill in the art will recognize that the voltages required to drive gas evolution at the electrodes, thereby favoring metal deposition and suppressing oxide formation, will vary based on the metals being electrodeposited and the electrolyte system in use.
EXAMPLES
[0263] The present technology will now be described with respect to particular exemplary embodiments, which are not intended to limit the scope of the present disclosure. For all examples discussed below, persons of ordinary skill in the art will understand that other device constructions are possible and would not depart from the scope and spirit of this disclosure.
Example 1. Continuous Electrorefining of Cobalt from Cobalt Hydroxides
[0264] To demonstrate continuous extraction of cobalt metal from crude cobalt hydroxide (35-40 wt. % Co) obtained from the cobalt-copper mines of the central African copperbelt, a continuous electrodeposition process was performed using the continuous electrodeposition apparatus of the present disclosure. An electrolyte was prepared by mixing solid NaOH, solid KOH, and crude cobalt hydroxide to reach mass fractions of 0.25 to 0.50, 0.30 to 0.55, and 0.05 to 0.30, respectively. The mixture was added to a vessel for a CERC as disclosed in
[0265] The results show that the continuous refinement apparatus and method according to the present disclosure can be used to extract elemental metals that have been successfully demonstrated on the batch scale.
Example 2. Demonstration-Scale Refinement of Cobalt from Cobalt Hydroxides
[0266] To demonstrate that successful electrodeposition methods at the demonstration scale and laboratory scale can be translated to successful continuous electrodepositions using the continuous electrodeposition apparatus and methods according the present disclosure, refinement of cobalt from cobalt hydroxides was performed using a demonstration-scale apparatus (this Example) and a laboratory-scale apparatus (see Examples 3-4). Thus, one of ordinary skill in the art will recognize that the continuous electrodeposition apparatus may be used to refine a wide variety of metals from a broad range of potential feedstocks.
[0267] Electrorefining/electroplating/electrowinning experiments were performed in the demonstration scale setup described in
TABLE-US-00001 TABLE 1 Summary of data relating to four consecutive runs for Co extraction using the demonstration-scale prototype cell. Areal Mass Runtime Amp-Hours Cathode Area Mass Rate Run # (hr) (Ah) (m.sup.2) (kg) (kg/h-m.sup.2) 1 16 120 0.194 0.072 0.023 2 16 110 0.194 0.072 0.023 3 24 150 0.097 0.130 0.056 4 60 883 0.146 0.679 0.078
[0268] Table 2 provides the purity (wt. %) of select samples of copper and cobalt obtained from the two setups (lab-scale and demonstration scale). This shows the possibility of obtaining copper of >98% purity and cobalt of >99.5% purity with the methods disclosed herein.
TABLE-US-00002 TABLE 2 ICP data showing purity levels for the electrodeposited copper and cobalt samples. Purity from ICP-OES Sample (wt. %) Lab-scale Cu 98.49 Lab-scale Co 96.99 Demonstration scale Co (Run 4) 99.92
[0269] It is further possible to co-plate Cu and Co on the cathodes in a single experiment. This can be achieved by skipping the copper removal step, thereby maintaining a high copper concentration in the molten salt electrolyte. As a result of applying a more negative voltage to the cathode than required for electrodepositing copper (i.e., for the purpose of extracting cobalt metal), the product on the cathodes is a mixed copper-cobalt metallic film.
[0270] Table 3 provides a comparison of the electrical energy consumption for molten salt electrorefining methods, using both a small-scale setup and a demonstration scale setup, as compared to an aqueous sulfate solution electrorefining method. The results demonstrate significant improvements in energy consummation by embodiments using the molten salt electrorefining process.
TABLE-US-00003 TABLE 3 Electrical energy consumption for electrorefining of Co from CoSO.sub.4 Industrial Average Laboratory Scale Demonstration Scale (Aqueous Sulfate (Molten Salt (Molten Salt Solution Electrorefining) Electrorefining) Electrorefining) Average Current 300-400 300 100 Density (A/m.sup.2) Cell Voltage 4.0-4.5 ~0.8 ~0.8 (V) Energy/Mass Co 3.71-4.12 ~0.73 ~1.04 (kWh/kg)
*Laboratory-scale setup uses pulsed waveform (square voltage wave)calculations consider pulse on phase only (hours of pulse on time, average current during pulse on time).
[0271] Key advantages of the process described are as follows: [0272] Lower temperature process (200-500 C. vs. 800 C. or higher) [0273] Ability to use low-purity and low-cost precursors [0274] Cobalt purity is >98% [0275] Low water usagewater is used mainly for the rinsing step of the process [0276] Reduced water usage relative to hydrometallurgical metal refining processes. [0277] Reduced energy usage relative to pyrometallurgical metal refining processes. [0278] Low environmental impact relative to other metal refinement processes [0279] Does not generate CO.sub.2 emissions or greenhouse gases that are generated form the classical Hall-Heroult molten salt electrolysis process for aluminum oxide reduction to aluminum metal. [0280] No generations of byproduct hazardous chlorine gas from chloride-based molten salt electrolysis processes. [0281] No generation of byproduct perfluorocarbons where reaction between graphite-based electrodes and fluoride-based molten salts in metal purification molten salt processes. [0282] No use of toxic organics or large amounts of waste usually seen in hydrometallurgical processes. [0283] Ability to recycle and reuse molten saltsno loss of molten salts used in the process (unless due to degradation or decomposition at voltage stability limits)only consumes precursor ores for the salts that dissolve in the bath to produce Co(II) and Cu(II) ions [0284] Capability to electroplate low concentrations of metal oxide-containing feedstocks thus reducing the volume of potential residual waste streams, and tailing streams with residual low level metal contaminants. [0285] Post metal-plating, residual caustic-based molten salts are still useful for potential alternative uses.
Example 3. General Procedure for Laboratory-Scale Experiments
[0286] To test the electrodeposition method for various feedstocks containing metals to be extracted, electrodeposition experiments were formed on the laboratory scale according to the following general procedure. These experiments were carried out to demonstrate that successful electrodepositions carried out on the laboratory scale can be translated to the continuous electrodeposition apparatus and method of the present disclosure.
[0287] Electrochemical Setup. In an inert-atmosphere glove box a 50-mL alumina crucible (for chloride molten salts) or a 50-mL nickel crucible (for hydroxide molten salts) is fitted with a three-electrode setup for electrochemical testing. Platinum wires are typically used for the working and counter electrodes, as well as for the reference electrode. The Ni or alumina crucible is cleaned via sandblasting, followed by rinsing with water and ethanol, then is dried in an oven. The crucible is then wrapped in a ceramic fiber mat for insulation prior to electrochemical testing. The crucible is pre-heated on a hot plate before addition of a molten salt electrolyte mixture. This setup is shown in
[0288] Molten Salt Eutectic. A molten salt eutectic is prepared to provide the desired relative concentrations of the salts within the molten salt electrolyte. For instance, for a binary NaOHKOH molten salt system with 51.5 mol % NaOH, approximately 21.24 g NaOH (97 wt. %) and 32.01 g KOH (85 wt. %) are added to the pre-heated crucible to prepare approximately 36 mL of molten salt electrolyte. Once the salts have melted, the hotplate temperature is adjusted to achieve a temperature of about 300 C.
[0289] Cyclic Voltammetry. To obtain a background cyclic voltammogram (CV), the three-electrode setup is prepared using Pt working and counter electrodes. The reference electrode may be Pt or may be to metal to be extracted. After the electrodes are immersed in the molten salt electrolyte, a potentiostat is used to obtain a background CV over the bath electrochemical stability window using a scan rate of (e.g., 100 mV/s). Once the background CV is obtained, the three-electrode setup is removed and cleaned.
[0290] To obtain a CV of the metal feedstock, the metal compound is added to the molten salt eutectic at a concentration of about 0.1 M, and the three-electrode setup is immersed in the molten salt eutectic. A potentiostat is used to scan the voltage over the previously determined bath electrochemical stability window. The obtained CV is then compared to the background CV to identify peaks or redox couples attributable to the metal compound or any changes to the electrochemical stability window. If a reduction peak is identified, then this may indicate potential for the metal ions to reduce to the elemental metal on the working electrode.
[0291] If no new peaks are observed in the metal compound CV (e.g., reduction peaks), it is possible that the hydrogen evolution reaction (HER) in the cathodic region of the CV obscures the presence of metal reduction peaks that could exist at lower or more negative potentials. Under suitable experimental conditions specific to each element or feedstock, a negative shift in the onset potential for HER in the CV may be induced, permitting observation of previously obscured redox couples and reduction peaks (if present) in the CV.
[0292] Electrolytic Reduction. Electrolytic reduction of the metal species is achieved by immersing the three-electrode setup in the metal feedstock solution in molten salt eutectic. A potentiostat is used to hold the voltage (versus reference) at the reduction voltage identified in the CV or (if no reduction voltage is identified) at an arbitrary negative voltage beyond the electrochemical stability window. The reduction voltage is maintained long enough to permit accumulation of enough material for chemical analysis. The working electrode is rinsed with deionized water (or acidic solution) in a fume hood or glove box, then dried.
[0293] Material deposited onto the working electrode is then analyzed by SEM, EDS, ICP, XRD, or other suitable methods.
Example 4. Laboratory-Scale Refinement of Co from Cobalt Hydroxides
[0294] To demonstrate that successful electrodepositions carried out on the laboratory scale and/or demonstration scale can be translated to the continuous electrodeposition apparatus and method of the present disclosure, laboratory-scale experiments were conducted to show electrorefinement of Co from Co(OH).sub.2 feedstock.
[0295] For this experiment, crude Co(OH).sub.2 was obtained from copper-cobalt mines from the central African Copperbelt and contained a large fraction of impurities are related to ore processing, the major impurities being copper and magnesium salts and oxides. Other impurities include Mn and Ni salts. In order to produce pure cobalt metal, it is desired to selectively remove the copper content which will otherwise co-plate along with the electrochemically extracted cobalt metal.
[0296] A molten salt mixture (electrolyte) was prepared by mixing and melting 85% KOH flakes, 98% NaOH flakes and about 97% Co(OH).sub.2 powders. A cyclic voltammogram was recorded using a platinum working electrode, platinum reference electrode and nickel counter electrode. This CV is included in
[0297] Next, CuSO.sub.4.Math.5H.sub.2O was added to the mixture to reach an estimated concentration of 0.05M. A cyclic voltammogram was recorded in this mixture using a similar setup as described previously. This CV is also included in
[0298] A molten salt mixture (i.e. molten hydroxide electrolyte) was prepared by mixing and melting 85% KOH flakes, 98% NaOH flakes and crude Co(OH).sub.2 from the Central African Copperbelt. The mixture temperature was maintained between 250 C. and 300 C. An electroplating experiment was carried out by preparing flat rectangular electrodes from metal foils (Ni foil as anode and SS304 as cathode). A copper wire was used as a reference electrode.
[0299] The experiment is carried out in the molten salt electrolyte with a setup as shown in
TABLE-US-00004 TABLE 4 Energy dispersive x-ray spectroscopy (EDS) data showing composition of the electrodeposited copper in the purification step ahead of cobalt deposition. Element Atomic % Weight % Net Counts Ni 1.94 1.8 4963 Cu 98.06 98.2 250682
[0300] The resulting electrolyte which is now relatively copper-free was used to extract cobalt onto the cathode. A similar setup was used as described for the extraction of copper in the above paragraph. A nickel foil electrode was used as the anode, a SS304 foil electrode was used as the cathode and a cobalt wire is used as the reference. In order to extract cobalt, the voltage applied to the cathode was set to any negative voltage compared to a cobalt reference, however, to avoid hydrogen evolution (which would reduce the faradaic efficiency), the preferred range is 0 to 0.25V vs cobalt reference. The choice of voltage determines the morphology of the plated metallower magnitude results in the formation of a film, whereas, applying a higher magnitude results in the formation of dendrites. The applied voltage was tailored as required for the required morphology. For this particular example, the voltage applied was 0.100 V vs cobalt reference. The potentiostat was programmed to apply voltage pulses of 0.100V vs the cobalt reference to the working electrode (SS304 cathode). The on and off times for the pulses were tailored to our needs and our choice of desired morphology. At the end of the experiment, when the current response dropped to nearly 0 mA (indicating all of the cobalt has been reduced), the electrode was removed from the setup and the electroplated cobalt was recovered by rinsing in dilute citric acid to remove excess salts (from the electrolyte) and scraping off the highly pure cobalt film using tweezers or a spatula. The cobalt film or particles so generated were then rinsed in DI water and alcohol.
TABLE-US-00005 TABLE 5 Energy dispersive x-ray spectroscopy (EDS) data showing composition of the electrodeposited cobalt. Element Atomic % Weight % Net Counts Mn 0.40 0.37 1553 Fe 0.54 0.51 2101 Co 98.48 98.52 384120 Ni 0.32 0.32 1266 Cu 0.25 0.27 992
[0301] In sum, the data obtained from the laboratory-scale, demonstration-scale, and continuous deposition experiments evidence that metals can be successfully electrodeposited at the laboratory- and demonstration-scales, and the results can be translated to successful electrodepositions at in a continuous deposition apparatus.
[0302] Examples 5-30 are included to provide additional examples of laboratory scale electrodepositions that can be successfully translated to continuous electrodeposition processes using molten salt electrolytes.
Example 5. Laboratory-Scale Electrorefining of Cobalt from Cobalt Sulfide
[0303] To demonstrate that methods according to the present disclosure can extract purified cobalt from cobalt (II) sulfide, a 0.10 M solution of CoS in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 285 C. before obtaining a CV of the CoS mixture (
[0304] Next, to demonstrate that the methods according to the present disclosure can extract a range of purified transition metals, semi-metals, alkaline earth metals, and metalloids, laboratory-scale electrodepositions were performed using feedstocks containing a wide range of metals (Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd) present in a wide range of feedstocks (e.g., hydroxides, oxides, and sulfides). These experiments are described below.
Example 6. Laboratory-Scale Electrorefining of Gallium from Gallium Oxide and Bauxite
[0305] To demonstrate that methods according to the present disclosure can extract a purified gallium from gallium oxides, a 0.1 M solution of Ga.sub.2O.sub.3 in NaOHKOH (51.5 mol % NaOH) was prepared and heated at 350 C. overnight before obtaining a CV of the Ga.sub.2O.sub.3 mixture (
[0306] As further evidence that gallium can be extracted from naturally-occurring, oxide-containing impure feedstocks, a 4 wt. % composition comprising bauxite (sourced from Arkansas, United States) was prepared in NaOHKOH (51.5 mol. % NaOH) before obtaining a CV of the bauxite composition (
Example 7. Laboratory-Scale Electrorefining of Gallium from Gallium Sulfide
[0307] To demonstrate that methods according to the present disclosure can extract purified Ga (or Ga.sub.2O) from Ga.sub.2S.sub.3, a 0.1M solution of Ga.sub.2S.sub.3 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Ga.sub.2S.sub.3 mixture (
Example 8. Laboratory-Scale Electrorefining of Magnesium from Magnesium Hydroxide
[0308] To demonstrate that methods according to the present disclosure can extract purified magnesium from magnesium (II) hydroxide, a 0.4 M solution of Mg(OH).sub.2 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Mg(OH).sub.2 mixture (
Example 9. Laboratory-Scale Electrorefining of Aluminum from Aluminum Hydroxide
[0309] To demonstrate that methods according to the present disclosure can extract purified aluminum from aluminum (III) hydroxide, a 0.3 M solution of Al(OH).sub.3 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 310 C. before obtaining a CV of the Al(OH).sub.3 mixture (
Example 10. Laboratory-Scale Electrorefining of Tin from Tin Sulfide
[0310] To demonstrate that methods according to the present disclosure can extract purified tin from tin (II) sulfide, a 0.10 M solution of SnS in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 225 C. before obtaining a CV of the SnS mixture (
Example 11. Laboratory-Scale Electrorefining of Silver from Silver Sulfide
[0311] To demonstrate that methods according to the present disclosure can extract purified silver from silver (I) sulfide, a 0.10 M solution of Ag.sub.2S in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 310 C. before obtaining a CV of the Ag.sub.2S mixture (
Example 12. Laboratory-Scale Electrorefining of Copper from Copper Sulfide
[0312] To demonstrate that methods according to the present disclosure can extract purified copper from copper (I) sulfide, a 0.10 M solution of CuS in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the CuS mixture (
Example 13. Laboratory-Scale Electrorefining of Nickel from Nickel Sulfide
[0313] To demonstrate that methods according to the present disclosure can extract purified nickel from nickel (II) sulfide, a 0.10 M solution of NiS in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 320 C. before obtaining a CV of the NiS mixture (
Example 14. Laboratory-Scale Electrorefining of Nickel from Nickel Hydroxide Product
[0314] To demonstrate that methods according to the present disclosure can extract purified nickel from nickel hydroxide product (NHP), a crude product which majorly consists a mixture of Ni(OH).sub.2.Math.H.sub.2O, Ni.sub.5(OH).sub.6(CO.sub.3).sub.2 and NiSO.sub.4.Math.6H.sub.2O concentrated from nickel ores, a 1.8 wt. % solution of NHP in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 265 C. before obtaining a CV of the NHP mixture (
Example 15. Laboratory-Scale Electrorefining of Zinc from Zinc Sulfide
[0315] To demonstrate that methods according to the present disclosure can extract purified zinc from zinc (II) sulfide, a 0.10 M solution of ZnS in NaOHKOH (51.5 mol % NaOH) was prepared and heated at 320 C. before obtaining a CV of the ZnS mixture (
Example 16. Laboratory-Scale Electrorefining of Antimony from Antimony Sulfide
[0316] To demonstrate that methods according to the present disclosure can extract purified antimony from antimony (III) sulfide, a 0.10 M solution of Sb.sub.2S.sub.3 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 305 C. before obtaining a CV of the Sb.sub.2S.sub.3 mixture (
Example 17. Laboratory-Scale Electrorefining of Chromium from Chromium Oxide
[0317] To demonstrate that methods according to the present disclosure can extract purified chromium from chromium(III) hydroxide, a 0.4 M solution of Cr(OH).sub.3 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Cr(OH).sub.3 mixture (
Example 18. Laboratory-Scale Electrorefining of Manganese from Manganese Oxide
[0318] To demonstrate that methods according to the present disclosure can extract purified manganese from manganese (II) oxide, a 0.4 M concentration solution of MnO in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 350 C. to obtain a CV of the MnO mixture (
Example 19. Laboratory-Scale Electrorefining of Iron from Iron Oxide
[0319] To demonstrate that methods according to the present disclosure can extract purified iron from iron (III) oxide, a 0.5 M solution of Fe.sub.2O.sub.3 feedstock in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Fe.sub.2O.sub.3 mixture (
Example 20. Laboratory-Scale Electrorefining of Strontium from Strontium Hydroxide
[0320] To demonstrate that methods according to the present disclosure can extract purified strontium from strontium (II) hydroxide, a 0.20 M solution of Sr(OH).sub.2 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Sr(OH).sub.2 mixture (
Example 21. Laboratory-Scale Electrorefining of Cadmium from Cadmium Sulfide
[0321] To demonstrate that methods according to the present disclosure can extract purified cadmium from cadmium (II) sulfide, a 0.1 M concentration solution of CdS feedstock in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the CdS mixture (
Example 22. Laboratory-Scale Electrorefining of Neodymium from Neodymium Oxide
[0322] To demonstrate that methods according to the present disclosure can extract purified neodymium from neodymium (III) oxide, a 0.20 M solution of Nd.sub.2O.sub.3 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the Nd.sub.2O.sub.3 mixture (
Example 23. Laboratory-Scale Electrorefining of Platinum from Platinum Sulfide
[0323] To demonstrate that methods according to the present disclosure can extract purified platinum from platinum (IV) sulfide, a 0.10 M solution of PtS.sub.2 in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 300 C. before obtaining a CV of the PtS.sub.2 mixture (
Example 24. Laboratory-Scale Electrorefining of Lead from Lead Oxide
[0324] To demonstrate that methods according to the present disclosure can extract purified lead from lead (II) oxide, a 0.10M solution of PbO in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 250 C. before obtaining a CV of the PbO mixture (
Example 25. Laboratory-Scale Electrorefining of Lead from Lead Sulfide
[0325] To demonstrate that methods according to the present disclosure can extract purified lead from lead (II) sulfide, a 0.10 M solution of PbS in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 250 C. before obtaining a CV of the PbS mixture (
Example 26. Laboratory-Scale Recycling of Lead from Lead Acid Battery (LAB) Anode
[0326] To demonstrate that methods according to the present disclosure can extract purified lead from a lead acid battery (LAB) anode from a used (end-of-life) LAB, a concentrated solution mixture of crushed LAB anode materials (including electrode (Pb), anode material (PbO.sub.2) and electrolyte (PbSO.sub.4, H.sub.2SO.sub.4)) in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 255 C. before obtaining a CV of the LAB anode mixture (
Example 27. Laboratory-Scale Recycling of Lead from Lead Acid Battery (LAB) Cathode
[0327] To demonstrate that methods according to the present disclosure can extract purified lead from the components of a lead acid battery (LAB), an end-of-life LAB was disassembled, and components were individually tested with no post processing. A section of the cathode grid material was removed from the LAB and added to a solution of NaOHKOH (51.5 mol. % NaOH) which was heated at 250 C. Some of the cathode material was removed before obtaining a CV of the LAB cathode in the molten salt mixture (
Example 28. Laboratory-Scale Recycling of Lead from Lead Acid Battery (LAB) Electrolyte
[0328] To demonstrate that methods according to the present disclosure can extract purified lead from the electrolyte of a lead-acid battery (LAB), an end-of-life LAB was disassembled, and components were individually tested with no post processing. A dried sample of PbSO.sub.4 with a mass of 34 mg was removed from the LAB and added to a solution of NaOHKOH (51.5 mol. % NaOH) which was heated at 250 C. before obtaining a CV in the molten salt mixture (
Example 29. Laboratory-Scale Recycling of Lead from Lead Acid Battery (LAB) Separator
[0329] To demonstrate that methods according to the present disclosure can extract purified lead from the electrolyte-soaked separator of a lead-acid battery (LAB), an end-of-life LAB was disassembled, and components were individually tested with no post processing. A 225 mg piece of separator material was removed from the LAB and added to the solution of NaOHKOH (51.5 mol. % NaOH) which was used to test the PbSO.sub.4. This solution was heated at 250 C. for 1 hour. Then, the separator was removed before obtaining a CV of the mixture (
Example 30. Laboratory-Scale Recycling of Copper from Copper Metal Scrap
[0330] To demonstrate that methods according to the present disclosure can oxidize a copper metal counter electrode and subsequently reduce the oxidized copper again to copper metal on a working electrode from element feedstock, a concentration solution of feedstock chemical formula in NaOHKOH (51.5 mol. % NaOH) was prepared and heated at 310 C. for time before obtaining a CV of the feedstock chemical formula mixture (
[0331] The present disclosure has described the use of various features and methods for electrorefining metals from impure metal compounds. It should be understood that any combination of such features and methods are within the scope of the present disclosure. For example, an embodiment that describes the use of a CERC to electrodeposit cobalt metal may be modified to separate and refine different metals (e.g., Nd, Co and Cu, etc.), and such modification is intended to be within the scope of the present disclosure. Other permutations and combinations that utilize one or more of the features/methods described herein are also possible, and such permutations and combinations are also considered part of the present disclosure without enumerating them specifically (for instance extraction of Nd from a permanent magnet of the type NdFeB or the extraction of Co and/or Sm from permanent magnets (new or used or waste magnets) of the SmCo type).
NUMBERED EMBODIMENTS
[0332] 1. A method for electrodeposition of an elemental metal onto an electrode from a feedstock comprising the elemental metal, the method comprising: [0333] providing the feedstock to a molten salt electrolyte comprising hydroxide-containing salts; [0334] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0335] applying a first voltage to the working electrode and counter-electrode that is sufficient to electrodeposit a first metal in elemental form, from the feedstock onto the working electrode.
[0336] 2. The method of embodiment 1, wherein the first metal is an alkali metal, alkaline earth metal, transition metal, post-transition metal, or metalloid.
[0337] 3. In some embodiments, the first metal is selected from the group consisting of: Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd. In some embodiments, the first metal has an average oxidation state of 1+ to 4+ in the feedstock.
[0338] 4. The method of any one of embodiments 1-3, wherein the first metal is Co.
[0339] 5. The method of any one of embodiments 1-4, wherein the feedstock comprises a hydroxide, an oxide, a sulfide, a nitrate, a sulfate, or a halide of the first metal, or any combination thereof.
[0340] 6. The method of any one of embodiments 1-5, wherein the feedstock comprises a hydroxide, an oxide, or a sulfide of the first metal.
[0341] 7. The method according to any one of embodiments 1-6, wherein the working electrode is a cathode.
[0342] 8. The method according to any one of embodiments 1-7 wherein the first metal is cobalt and the cobalt is electrodeposited by reduction from a Co(II) oxidation form present in the feedstock onto the working electrode.
[0343] 9. The method according to any one of embodiments 1-8, wherein the feedstock comprises from 10 wt. % to 50 wt. %, relative to the total weight of the feedstock, of compounds comprising the first metal.
[0344] 10. The method according to any one of embodiments 1-9, wherein the feedstock comprises one or more of Co(OH).sub.2, CoSO.sub.4, CoCl.sub.2, and Co(NO.sub.3).sub.2.
[0345] 11. The method according to any one of embodiments 1-10, wherein the feedstock comprises impurities selected from the group consisting of nickel-containing, manganese-containing, and copper-containing compounds.
[0346] 12. The method according to any one of embodiments 1-11, wherein the feedstock comprises 10 wt. % or less of copper-containing compounds, relative to the total weight of the feedstock.
[0347] 13. The method according to any one of embodiments 1-12, wherein the feedstock comprises 1 wt. % or less of copper-containing compounds, relative to the total weight of the feedstock.
[0348] 14. The method according to any one of embodiments 1-13, wherein the method further comprises: [0349] applying a second voltage to the working electrode and the counter-electrode that is sufficient to electrodeposit a second metal in elemental form, from the feedstock onto the working electrode.
[0350] 15. The method according to embodiment 14, wherein the second voltage is at least 100 mV more negative than the first voltage.
[0351] 16. The method according to embodiment 14 or 15, wherein the first metal deposited in elemental form is removed from the working electrode before application of the second voltage to electrodeposit the second metal from the feedstock.
[0352] 17. The method according to any one of embodiments 14-16, wherein the first metal and the second metal are selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, or metalloids.
[0353] 18. The method according to any one of embodiments 14-17, wherein the first metal or the second metal is selected from the group consisting of: Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd.
[0354] 19. The method according to any one of embodiments 1-3 and 5-18, wherein the first metal is copper and the second metal is cobalt.
[0355] 20. The method according to any one of embodiments 1-19, wherein the first voltage or the second voltage is a steady state voltage.
[0356] 21. The method according to any one of embodiments 1-20, wherein the first voltage or the second voltage is applied in the form of a pulsed wave or a series or plurality of pulsed waves.
[0357] 22. The method according to any one of embodiments 1-21, wherein a flow of the molten salt electrolyte is circulated past the working electrode during application of the first voltage or the second voltage.
[0358] 23. The method according to any one of embodiments 1-22, wherein the working electrode is a high surface area electrode.
[0359] 24. The method according to any one of embodiments 1-23, wherein the working electrode comprises a plurality of cylinders extending into the molten salt electrolyte.
[0360] 25. The method according to any one of embodiments 1-23, wherein the working electrode comprises a rectangular electrode with opposing faces each having a higher surface area than other faces of the working electrode.
[0361] 26. The method according to any one of embodiments 1-25, wherein: [0362] a flow of the molten salt electrolyte is circulated past the working electrode; and [0363] the working electrode comprises the highest surface area face that is parallel to a direction of the flow of the molten salt electrolyte.
[0364] 27. The method according to any one of embodiments 1-26, wherein: [0365] the working electrode comprises a high surface area electrode; or [0366] the counter-electrode comprises a high surface area electrode.
[0367] 28. The method according to any one of embodiments 1-27, wherein the working electrode or counter-electrode comprises a plurality of cylindrical or rectangular electrodes.
[0368] 29. The method according to any one of embodiments 1-28, wherein: [0369] the working electrode comprises a plurality of cylindrical electrodes; and [0370] the counter-electrode comprises a plurality of rectangular electrodes.
[0371] 30. The method according to any one of embodiments 1-29, wherein a flow of molten salt electrolyte is circulated past the working electrode by a pump in a bath in which the molten salt electrolyte is contained.
[0372] 31. The method according to any one of embodiments 1-30, wherein the molten salt electrolyte comprises alkali hydroxides.
[0373] 32. The method according to any one of embodiments 1-31, wherein the molten salt electrolyte comprises one or more of the following compounds in a fully molten state: LiOH, KOH, NaOH and CsOH.
[0374] 33. The method according to any one of embodiments 1-32, wherein the molten salt electrolyte comprises a binary molten salt system of type Salt1Salt2, wherein: [0375] Salt1+Salt2=100% by weight of the total molten salt.
[0376] 34. The method according to embodiment 33, wherein the binary molten salt system of type Salt1Salt2 is selected from the group consisting of: [0377] LiOHKOH; [0378] LiOHNaOH; [0379] LiOHCsOH; [0380] KOHNaOH; [0381] KOHCsOH; and [0382] NaOHCsOH.
[0383] 35. The method according to embodiment 33 or 34, wherein: [0384] Salt 1 is present in the binary molten salt system at a molar concentration ([Salt1]) of 1 mol % to 100 mol %; and [0385] Salt 2 is present in the binary molten salt system at a molar concentration of (100 mol %[Salt1]).
[0386] 36. The method according to any one of embodiments 1-32, wherein: [0387] the molten salt electrolyte comprises a ternary molten salt system of type Salt1Salt2Salt3, wherein: [0388] Salt1+Salt2+Salt3=100% by weight of the total molten salt.
[0389] 37. The method of embodiment 36, wherein the ternary molten salt system is selected from the group consisting of: [0390] LiOHKOHNaOH; [0391] LiOHKOHCsOH; [0392] KOHNaOHCsOH; and [0393] LiOHNaOHCsOH.
[0394] 38. The method according to embodiment 36 or 37, wherein: [0395] Salt 1 is present in the ternary molten salt system at a molar concentration ([Salt1]) of 1 mol % to 100 mol %; [0396] Salt 2 is present in the ternary molten salt system at a molar concentration ([Salt2]) of 1 mol % to 100 mol %; and [0397] Salt 3 is present in the binary molten salt system at a molar concentration of (100 mol %([Salt1]+[Salt2])).
[0398] 39. The method according to any one of embodiments 1-32, wherein the molten salt electrolyte comprises a quaternary salt system LiOHKOHNaOHCsOH, wherein Salt1+Salt2+Salt3+Salt4=100% by weight of the total molten salt.
[0399] 40. The method according to any one of embodiments 1-39, wherein the working electrode comprises a cathode material comprising any one or more of the following: carbon, or a metal rod or foil comprising Pt, Ni, Co, Cu, Al or stainless steel.
[0400] 41. The method according to embodiment 40, wherein the working electrode comprises stainless steel, and the stainless steel is SS 304 or SS 316 grade stainless steel.
[0401] 42. The method according to any one of embodiments 1-41, wherein the molten salt electrolyte is at a temperature of 170 C. to 370 C.
[0402] 43. The method according to any one of embodiments 1-42, wherein the molten salt electrolyte is at a temperature of 200 C. to 350 C.
[0403] 44. The method according to any one of embodiments 1-43, wherein the molten salt electrolyte is at a temperature of 250 C. to 270 C.
[0404] 45. The method according to any one of embodiments 1-44, wherein the method achieves a current density of 1-50 mA/cm.sup.2.
[0405] 46. The method according to any one of embodiments 1-45, wherein the method achieves a current density of 5-25 mA/cm.sup.2.
[0406] 47. The method according to any one of embodiments 1-45, wherein the method achieves a current density of 25-50 mA/cm.sup.2.
[0407] 48. The method according to any one of embodiments 1-47, wherein cobalt metal is deposited on the working electrode, and the cobalt metal has a purity of greater than 98% as determined by EDX or ICP analysis.
[0408] 49. The method according to any one of embodiments 1-48, further comprising driving a counter-electrode reaction on the anode to produce a gaseous product, thereby increasing metal recovery from the process and reducing build-up of solid by-products on the anode.
[0409] 50. An apparatus for electrodeposition of an elemental metal onto an electrode from a feedstock comprising the metal, the apparatus comprising: [0410] a molten electrolyte bath configured to hold molten electrolyte salt comprising molten hydroxide salts; [0411] a heater configured to heat the molten hydroxide salts to a molten temperature in the molten electrolyte bath; [0412] a working electrode and a counter-electrode configured to be immersed in the molten electrolyte bath; [0413] a molten electrolyte circulation system configured to circulate a flow of molten electrolyte past the working electrode; and [0414] a voltage supply configured to apply a voltage to the working and counter electrodes, [0415] wherein: [0416] the voltage supply is configured to apply a voltage that is sufficient to electrodeposit a first metal provided in the feedstock into the molten electrolyte bath onto the working electrode in elemental form; and [0417] the molten electrolyte circulation system circulates the flow of molten electrolyte past the working electrode, during electrodeposition of the first metal onto the working electrode.
[0418] 51. The apparatus according to embodiment 50, wherein the voltage supply is configured to: [0419] apply a first voltage to the electrodes that is sufficient to electrodeposit the first metal in elemental form from a feedstock comprising the first metal and a second metal, onto the working electrode; and [0420] apply a second voltage that is more negative than the first voltage and that is sufficient to electrodeposit a second metal in elemental form from the feedstock, onto the working electrode.
[0421] 52. The apparatus according to embodiment 51, wherein the second voltage is at least 100 mV more negative than the first voltage.
[0422] 53. The apparatus according to any one of embodiments 50-52, wherein the apparatus is configured to drive a counter electrode reaction on the anode to produce a gaseous product, thereby increasing metal recovery from the process and reducing build-up of solid by-products.
[0423] 54. The apparatus according to any one of embodiments 50-53, wherein the molten electrolyte circulation system comprises one or more pumps configured to circulate the flow of molten electrolyte past the working electrode in the molten electrolyte bath.
[0424] 55. The apparatus according to any one of embodiments 50-54, wherein the molten electrolyte circulation system provides a continuous flow of the molten electrolyte across a surface of the working electrode during electrodeposition of the first metal or the second metal.
[0425] 56. The apparatus according to any of embodiments 50-55, wherein the first metal or the second metal is selected from alkali metals, alkaline earth metals, transition metals, post-transition metals, or metalloids.
[0426] 57. The apparatus according to any one of embodiments 50-56, wherein the first metal or the second metal is selected from the group consisting of: Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd.
[0427] 58. The apparatus according to embodiment 50, wherein the first metal is cobalt.
[0428] 59. The apparatus according to any one of embodiments 51-57, wherein: [0429] the first metal is copper; and [0430] the second metal is cobalt.
[0431] 60. The apparatus according to any one of embodiments 50-59, wherein the working electrode is a cathode.
[0432] 61. The apparatus according to any one of embodiments 50-60, wherein the apparatus is further configured to remove the first metal electrodeposited in elemental form from the working electrode before application of the second voltage to electrodeposit the second metal from the feedstock.
[0433] 62. The apparatus according to any of embodiments 50-61, wherein the voltage supply is configured to apply the first voltage or second voltage in the form of a steady state voltage.
[0434] 63. The apparatus according to any of embodiments 50-62, wherein the voltage supply is configured to apply the first voltage or the second voltage in the form of a pulsed wave, or a series or plurality of pulsed waves.
[0435] 64. The apparatus according to any one of embodiments 50-63, wherein the working electrode is a high surface area electrode.
[0436] 65. The apparatus according to any one of embodiments 50-64, wherein the working electrode comprises a plurality of cylinders extending into the molten salt electrolyte.
[0437] 66. The apparatus according any one of embodiments 50-64, wherein the working electrode comprises a rectangular electrode with opposing faces each having a higher surface area than other faces of the working electrode.
[0438] 67. The apparatus according to any of embodiments 50-66, wherein molten electrolyte circulation system is configured to circulate a flow of the molten salt electrolyte past the working electrode, and wherein the working electrode comprises a highest surface area face that is parallel to a direction of flow of the molten salt electrolyte.
[0439] 68. The apparatus according to any of embodiments 50-57, comprising a plurality of working electrodes and/or counter-electrodes that are high surface area electrodes.
[0440] 69. The apparatus according to embodiment 68, wherein the working electrode or counter-electrode comprises a plurality of cylindrical or rectangular electrodes.
[0441] 70. The apparatus according to embodiment 69, wherein the working electrode and counter-electrode each comprise a plurality of cylinders in alternating rows.
[0442] 71. The apparatus according to embodiment 69, wherein the working electrode and counter-electrode each comprise a plurality of rectangular electrodes in alternating rows.
[0443] 72. The apparatus according to embodiment 69, wherein: [0444] the working electrode comprises a plurality of cylinders; and [0445] the counter-electrode comprises a plurality of rectangular electrodes, [0446] wherein the plurality of cylinders and plurality of rectangular electrodes are arranged in alternating rows.
[0447] 73. The apparatus according to any one of embodiments 50-72, wherein the molten salt electrolyte comprises alkali hydroxides.
[0448] 74. The apparatus according to any one of embodiments 50-73, where the molten salt electrolyte comprises any one of the following compounds: LiOH, KOH, NaOH or CsOH, in the fully molten state.
[0449] 75. The apparatus according to any one of embodiments 50-74, wherein the molten salt electrolyte comprises a binary molten salt system of type Salt1Salt2, wherein: [0450] Salt1+Salt2=100% by weight of the total molten salt.
[0451] 76. The apparatus according to embodiment 75, wherein the binary molten salt system of type Salt1Salt2 is selected from the group consisting of: [0452] LiOHKOH; [0453] LiOHNaOH; [0454] LiOHCsOH; [0455] KOHNaOH; [0456] KOHCsOH; and [0457] NaOHCsOH.
[0458] 77. The apparatus according to embodiment 75 or 76, wherein: [0459] Salt 1 is present in the binary molten salt system at a molar concentration ([Salt1]) of 1 mol % to 100 mol %; and [0460] Salt 2 is present in the binary molten salt system at a molar concentration of (100 mol %[Salt1]).
[0461] 78. The apparatus according to any one of embodiments 50-74, wherein: [0462] the molten salt electrolyte comprises a ternary molten salt system of type Salt1Salt2Salt3, wherein: [0463] Salt1+Salt2+Salt3=100% by weight of the total molten salt.
[0464] 79. The apparatus of embodiment 78, wherein the ternary molten salt system is selected from the group consisting of: [0465] LiOHKOHNaOH; [0466] LiOHKOHCsOH; [0467] KOHNaOHCsOH; and [0468] LiOHNaOHCsOH.
[0469] 80. The apparatus according to embodiment 78 or 79, wherein: [0470] Salt 1 is present in the ternary molten salt system at a molar concentration ([Salt1]) of 1 mol % to 100 mol %; [0471] Salt 2 is present in the ternary molten salt system at a molar concentration ([Salt2]) of 1 mol % to 100 mol %; and [0472] Salt 3 is present in the binary molten salt system at a molar concentration of (100 mol %([Salt1]+[Salt2])).
[0473] 81. The apparatus according to any one of embodiments 50-74, wherein the molten salt electrolyte comprises a quaternary salt system LiOHKOHNaOHCsOH, wherein Salt1+Salt2+Salt3+Salt4=100% by weight of the total molten salt.
[0474] 82. The apparatus according to any of embodiments 50-81, wherein the working electrode comprises a cathode electrode material comprising any one or more of the following: carbon, or a metal rod or foil composed of Pt, Ni, Co, Cu, Al or stainless steel (SS 304/316 grades).
[0475] 83. The apparatus according to any of embodiments 50-82, wherein the heater is capable of heating the molten salt electrolyte in the molten electrolyte bath to a temperature that is between 170 C. and 370 C.
[0476] 84. The apparatus according to any of embodiments 50-83, wherein the voltage supply is configured to supply a voltage that provides a current density of the process that may range from 1 mA/cm.sup.2 to 50 mA/cm.sup.2.
[0477] 85. A method for electrodeposition of a first metal onto an electrode from a feedstock comprising the first metal, the method comprising: [0478] providing the feedstock to a molten salt electrolyte comprising hydroxide-containing salts; [0479] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0480] applying a voltage to the electrodes that is sufficient to electrodeposit the first metal from the feedstock onto the working electrode in elemental form, [0481] wherein: [0482] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0483] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0484] 86. The method according to embodiment 85, further comprising driving a counter electrode reaction to a gaseous product, thereby increasing recovery of the first metal and reducing build-up of solid by-products on the anode.
[0485] 87. The method according to embodiment 85 or 86, wherein the first metal is a transition metal.
[0486] 88. The method according to any one of embodiments 85-87, wherein the first metal is cobalt.
[0487] 89. The method according to any one of embodiments 85-88, wherein the feedstock comprises any one or more of the compounds: Co(OH).sub.2, CoSO.sub.4, CoCl.sub.2, Co(NO.sub.3).sub.2.
[0488] 90. The method according to any one of embodiments 85-89, wherein the molten salt electrolyte comprises alkali hydroxides.
[0489] 91. The method according to any one of embodiments 85-90, wherein the molten salt electrolyte comprises at least one of LiOH, KOH, NaOH, or CsOH in the fully molten state.
[0490] 92. The method according to any one of embodiments 85-91, wherein the molten salt electrolyte comprises a binary molten salt system of type Salt1Salt2, wherein: [0491] Salt1+Salt2=100% by weight of the total molten salt.
[0492] 93. The method according to embodiment 92, wherein the binary molten salt system of type Salt1Salt2 is selected from the group consisting of: [0493] LiOHKOH; [0494] LiOHNaOH; [0495] LiOHCsOH; [0496] KOHNaOH; [0497] KOHCsOH; and [0498] NaOHCsOH.
[0499] 94. The method according to embodiment 92 or 93, wherein: [0500] Salt 1 is present in the binary molten salt system at a molar concentration ([Salt1]) of 1 mol % to 100 mol %; and [0501] Salt 2 is present in the binary molten salt system at a molar concentration of (100 mol %[Salt1]).
[0502] 95. The method according to any one of embodiments 85-94, further comprising electrodepositing a second metal from the metal-containing ore or feedstock onto the counter electrode in elemental form.
[0503] 96. The method according to any one of embodiments 85-96, wherein the obtained metal in elemental form or second metal in elemental form is at least 95% pure, as determined by ICP analysis.
[0504] 97. A method of recycling a metal from an impure feedstock, the method comprising: [0505] (a) solubilizing a metal from the impure feedstock in an acidic solution to obtain a metal composition; and [0506] (b) electrodepositing the metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0507] providing the metal composition to a molten salt electrolyte comprising hydroxide-containing salts; [0508] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0509] applying a first voltage to the working electrode and counter-electrode that is sufficient to electrodeposit a first metal in elemental form, from the feedstock onto the working electrode.
[0510] 98. A method of recycling a metal from an impure feedstock, the method comprising: [0511] (a) solubilizing a metal from the impure feedstock in an acidic solution to obtain a metal composition; and [0512] (b) electrodepositing the metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0513] providing the metal composition to a molten salt electrolyte comprising hydroxide-containing salts; [0514] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0515] applying a voltage to the electrodes that is sufficient to electrodeposit the metal from the molten salt electrolyte onto the working electrode in elemental form, [0516] wherein: [0517] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0518] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0519] 99. A purified metal obtained by the method according to any one of embodiments 1-49 and 85-98.
[0520] 100. An electrodeposition apparatus, comprising: [0521] a working electrode comprising a rotary drum having a central axis and a lateral surface, wherein the rotary drum is configured to rotate about the central axis; [0522] a counter electrode, wherein a surface of the counter electrode opposite the working electrode is at least partially concentric with the lateral surface of the working electrode; and [0523] a vessel with an electrolyte bath disposed therein, the electrolyte bath comprising a molten salt electrolyte comprising hydroxide-containing salts, [0524] wherein the lateral surface of the working electrode is configured to be at least partially submerged in the electrolyte bath.
[0525] 101. The electrodeposition apparatus of embodiment 100, wherein the counter electrode has an arc shape.
[0526] 102. The electrodeposition apparatus of embodiment 100 or 101, further comprising a scraping member configured to separate electrodeposited metal from the lateral surface of the rotary drum as the rotary drum rotates about the central axis.
[0527] 103. The electrodeposition apparatus of any one of embodiments 100-102, further comprising a fluid flow apparatus configured to transport electrolyte bath into the vessel and/or out of the vessel.
[0528] 104. The electrodeposition apparatus of any one of embodiments 100-103, further comprising a containment apparatus configured to isolate the electrolyte bath from the ambient atmosphere, wherein the electrolyte bath is in contact with an inert atmosphere comprising at least about 99 vol. % nitrogen gas or argon gas.
[0529] 105. The electrodeposition apparatus of any one of embodiments 100-104, further comprising: [0530] a potentiostat configured to control a voltage across the working electrode and the counter electrode; and/or [0531] a galvanostat configured to control a current flowing between the working electrode and the counter electrode.
[0532] 106. The electrodeposition apparatus of any one of embodiments 100-105, wherein the lateral surface of the rotary drum is corrugated.
[0533] 107. The electrodeposition apparatus of any one of embodiments 100-106, wherein the molten salt electrolyte comprises one or more of LiOH, NaOH, KOH, and CsOH.
[0534] 108. The electrodeposition apparatus of any one of embodiments 100-107, wherein the electrolyte bath further comprises a feedstock comprising a first metal, wherein the first metal is in an average oxidation state of +3 or less in the feedstock.
[0535] 109. A method for electrodeposition of a first metal onto an electrode from a feedstock comprising the first metal, the method comprising: [0536] providing the feedstock to a molten salt electrolyte comprising hydroxide-containing salts, wherein the first metal is in an average oxidation state of +3 or less in the feedstock; [0537] contacting a working electrode and a counter electrode with the molten salt electrolyte comprising the feedstock; and [0538] applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, [0539] wherein: [0540] the working electrode comprises a rotary drum having a central axis and a lateral surface, wherein the rotary drum rotates about the central axis while the voltage is applied; and [0541] at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about the central axis.
[0542] 110. The method of embodiment 109, wherein the first metal is selected from the group consisting of: Mg, Co, Ni, Ag, Cu, Cr, Zn, Ga, Sn, Al, Sb, Pb, Fe, Cd, Mn, Pt, Sr and Nd.
[0543] 111. The method of embodiment 109 or 110, wherein the first metal has an average oxidation state of +2 or less in the feedstock.
[0544] 112. The method of any one of embodiments 109-111, wherein the molten salt electrolyte comprises one or more of LiOH, NaOH, KOH, and CsOH.
[0545] 113. The method of any one of embodiments 109-112, wherein the feedstock further comprises a second metal, wherein the second metal has an average oxidation state of +3 or less in the feedstock.
[0546] 114. The method of embodiment 113, wherein the voltage applied across the working electrode and the counter electrode is sufficient to co-deposit the first metal and the second metal onto the working electrode in elemental form.
[0547] 115. The method of embodiment 113, wherein after the first metal is electrodeposited onto the working electrode and the first metal is deposited onto the electrode in elemental form, a second voltage is applied across the working electrode and the counter electrode, wherein the second voltage is sufficient to electrodeposit the second metal onto the working electrode in elemental form.
[0548] 116. The method of any one of embodiments 109-115, wherein: [0549] the feedstock comprises one or more alloys, ores, concentrates, mine wastes, or tailings; or [0550] the feedstock comprises scrap comprising the first metal, and the counter electrode comprises a porous container in contact with the scrap, wherein the first metal is oxidized at the counter electrode before being electrodeposited in elemental form onto the working electrode.
[0551] 117. The method of any one of embodiments 109-116, wherein: [0552] the voltage applied across the working electrode and the counter electrode is held constant; or [0553] the voltage applied across the working electrode or the counter electrode is pulsed; or [0554] a current flowing between the working electrode and the counter electrode is held constant; or [0555] the current flowing between the working electrode and the counter electrode is pulsed.
[0556] 118. The method of any one of embodiments 109-117, wherein an atmosphere in contact with the molten salt electrolyte is isolated from ambient atmosphere and comprises at least about 99 vol. % nitrogen gas or argon gas.
[0557] 119. A method of recycling a metal from a feedstock, the method comprising: [0558] (a) solubilizing a first metal from the feedstock to obtain a metal composition, wherein the first metal is in an average oxidation state of 4+ or less in the feedstock; and [0559] (b) electrodepositing the first metal in elemental form onto an electrode from the metal composition, the electrodepositing comprising: [0560] providing the metal composition to a molten salt electrolyte comprising hydroxide-containing salts; [0561] contacting a working electrode and a counter electrode with the molten salt electrolyte; and [0562] applying a voltage across the working electrode and the counter electrode sufficient to electrodeposit the first metal onto the working electrode in elemental form, [0563] wherein: [0564] the working electrode comprises comprising a rotary drum having a central axis and a lateral surface, wherein the rotary drum is rotated about the central axis; and [0565] at least a portion of the lateral surface is submerged in the molten salt electrolyte while the rotary drum is rotated about the central axis.
[0566] 120. A method of recycling lead from a feedstock, the method comprising: (a) solubilizing lead from the feedstock to obtain a lead composition; and (b) electrodepositing the lead in elemental form onto an electrode from the lead composition, the electrodepositing comprising: [0567] providing the lead composition to a molten salt electrolyte; [0568] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0569] applying a voltage to the electrodes that is sufficient to electrodeposit the lead from the molten salt electrolyte onto the working electrode in elemental form, [0570] wherein: [0571] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0572] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0573] 121. The method of embodiment 120, wherein the feedstock comprises a lead-acid battery (LAB).
[0574] 122. In some embodiments, the feedstock comprises a LAB cathode, a LAB anode, a LAB separator, or LAB electrolyte.
[0575] 123. A method of recycling a metal from a feedstock, the method comprising: [0576] (a) solubilizing the metal from the feedstock to obtain a metal composition; and [0577] (b) electrodepositing the metal in elemental form onto an electrode from the lead composition, the electrodepositing comprising: [0578] providing the metal composition to a molten salt electrolyte; [0579] immersing a working electrode and a counter-electrode into the molten salt electrolyte; and [0580] applying a voltage to the electrodes that is sufficient to electrodeposit the metal from the molten salt electrolyte onto the working electrode in elemental form, [0581] wherein: [0582] the working electrode comprises a rotary drum having a substantially circular cross-section, and at least a portion of the working electrode is submerged in the molten salt electrolyte while the working electrode is rotated about a central axis; and [0583] the counter electrode surface opposite the working electrode is a stationary arc at least partially concentric with the working electrode, and the counter electrode is at least partially submerged in the molten salt electrolyte.
[0584] 124. The method of embodiment 123, wherein the metal is one or more of Nd, Sm, Co, Fe, and B.
[0585] 125. The method of embodiments 124 or 125, wherein the feedstock is a magnet comprising Sm, Co, Nd, Fe, B, or any combination thereof.
[0586] 126. The method of any one of embodiments, 123-125, wherein the feedstock is a NdFeB magnet.
[0587] 127. The method of any one of embodiments, 123-125, wherein the feedstock is a SmCo magnet.
DEFINITIONS AND EQUIVALENTS
[0588] Notwithstanding the embodiments described above and shown in the accompanying drawing figures, various modifications and inclusions to those embodiments are contemplated and considered within the scope of the present disclosure.
[0589] As utilized herein with respect to numerical ranges, the terms approximately, about, substantially, and similar terms generally mean +/10% of the disclosed values, unless specified otherwise. As utilized herein with respect to structural features (e.g., to describe shape, size, orientation, direction, relative position, etc.), the terms approximately, about, substantially, and similar terms are meant to cover minor variations in structure that may result from, for example, the manufacturing or assembly process and are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the disclosure as recited in the appended claims.
[0590] It should be noted that the term exemplary and variations thereof, as used herein to describe various embodiments, are intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (and such terms are not intended to connote that such embodiments are necessarily extraordinary or superlative examples).
[0591] The term coupled and variations thereof, as used herein, means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If coupled or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of coupled provided above is modified by the plain language meaning of the additional term (e.g., directly coupled means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of coupled provided above. Such coupling may be mechanical, electrical, or fluidic.
[0592] Connections between different components in communication with one another may be wired or wireless. In Figures referring to connectivity of two or more components in communication with one another show lines indicating the communication between components. By default, where these lines intersect, no contact is indicated, unless marked with a .
[0593] References herein to the positions of elements (e.g., top, bottom, above, below) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.
[0594] Although the figures and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above.
[0595] It is important to note that any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein. Although only one example of an element from one embodiment that can be incorporated or utilized in another embodiment has been described above, it should be appreciated that other elements of the various embodiments may be incorporated or utilized with any of the other embodiments disclosed herein.