Metal recovery electrochemical cell and system

Abstract

A metal recovery electrochemical cell includes a metal-based anode; a metal-based cathode; and a metal-based housing with a conical shape and a draft angle of about 0.01 to about 1 degree, the draft angle of the metal-based housing being an angle between a vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle.

Description

ELECTROCHEMICAL DEVICE AND SYSTEM FOR METAL RECOVERY CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 633,309, filed on April 12, 2024, which is incorporated by reference herein in its entirety.BACKGROUND

[0002] The present disclosure relates to metal recovery from a liquid stream using an electrochemical device.

[0003] Electrowinning is an electrochemical process used to recover metals from concentrated solutions, typically for example, in a range of 30 to 50 grams / Liter (g / L) or 30,000 to 50,000 parts-per-million (ppm). In this process, a voltage is applied across two electrodes, the positively charged anode and the negatively charged cathode, which are submerged in the concentrated metal containing solution. The anode can be, for example, a mixed-metal oxide (MMO), and the cathode can be, for example, 316 stainless steel or titanium (Ti). As a result, the positively charged metal ions will electrodeposit or electroplate out of the solution onto the cathode as a solid. This process can be used to recover metals, including but not limited to, copper, zinc, nickel, cobalt, gold, and / or silver, from wastewater streams.SUMMARY

[0004] According to some embodiments, a metal recovery electrochemical cell includes comprising: a metal-based anode; a metal-based cathode; and a metal-based housing with a conical shape and a draft angle of about 0.01 to about 1 degree, the draft angle of the metal-based housing being an angle between a vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle.

[0005] In some embodiments, the draft angle of the metal-based housing is about 0.15 to about 0.60 degrees.

[0006] In other embodiments, the metal-based cathode further comprises a draft angle that is an angle between the vertical centerline of the metal-based cathode and an adjacent vertical side of the metal-based cathode, when both are extrapolated to form an angle.

[0007] In one or more embodiments, the metal-based cathode draft angle is about 0.01 to about 1 degree.

[0008] In some embodiments, the draft angle of the metal-based cathode is about 0.15 to about 0.60 degrees.

[0009] In other embodiments, the metal recovery electrochemical cell further comprises a cylindrical edge guard on a top of the metal-based cathode.

[0010] Yet in other embodiments, the metal recovery electrochemical cell further comprises a cylindrical edge guard on a bottom of the metal-based cathode.

[0011] In one or more embodiments, the metal-based anode is a titanium-coated mixed-metal oxide.

[0012] In some embodiments, the metal-based cathode is a 316 stainless steel sheet.

[0013] In other embodiments, the metal-based housing comprises a 316 stainless steel.

[0014] Yet, in other embodiments, the metal recovery electrochemical cell of further comprises a separator between the metal-based anode and the metal-based cathode.

[0015] In one or more embodiments, the metal recovery electrochemical cell of further comprises a membrane arranged on the metal-based anode and the metalbased cathode.

[0016] In some embodiments, inner diameter of a first end of the metal-based housing is different than an inner diameter of a second end of the metal-based housing.

[0017] In other embodiments, the metal-based cathode comprises a metal with a linear polarization resistance (LPR) of less than 0.1 millimeters per year (mmpy), as measured by ISO 17475 - Corrosion of Metals and Alloys.

[0018] In some embodiments, a metal recovery electrochemical system comprises a metal purification electrochemical cell comprising at least one carbonbased electrode and at least one metal-based electrode; and a metal recovery electrochemical cell comprising a metal-based cathode and a metal-based anode, and a metal-based housing with a conical shape and a draft angle of about 0.01 to about 1 degree, the draft angle of the metal-based housing being an angle between a verticalcenterline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle; wherein the metal recovery electrochemical cell is arranged downstream from the metal purification electrochemical cell.

[0019] In some embodiments, the at least one carbon-based electrode is a carbon felt, a woven carbon cloth, a carbon film, a non-woven, or an activated carbon material.

[0020] In other embodiments, the at least one metal-based electrode comprises a metal with one or more metal oxides arranged on the metal.

[0021] Yet in other embodiments, the system further comprises a regeneration tank arranged between the metal purification electrochemical cell and the metal recovery electrochemical cell.

[0022] In some embodiments, a metal recovery electrochemical cell includes a metal-based anode; a metal-based cathode surrounding the metal-based anode; and a cap covering an end of the metal-based cathode, the cap comprising a cylindrical edge guard with an internal cylindrical wall, a medial cylindrical wall, and a circumferential wall.

[0023] In other embodiments, the metal recovery electrochemical cell further comprises a metal-based housing with a cylindrical shape.

[0024] Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0025] FIG. 1 A is a schematic front view of a metal recovery electrochemical cell according to some embodiments;

[0026] FIG. 1 B is a schematic cross-sectional side view of a metal recovery electrochemical cell according to some embodiments;

[0027] FIG. 2A is a schematic perspective view of an edge guard used in a metal recovery electrochemical cell according to some embodiments;

[0028] FIG. 2B is a schematic perspective view of an edge guard used in a metal recovery electrochemical cell according to some embodiments;

[0029] FIG. 20 is a schematic side view of a bottom cap used in a metal recovery electrochemical cell according to some embodiments;

[0030] FIG. 2D is a schematic cross-sectional side view of a bottom cap used in a metal recovery electrochemical cell according to some embodiments;

[0031] FIG. 3A is a process flow of a system for metal purification and recovery from a liquid stream with electrochemical cells according to some embodiments;

[0032] FIG. 3B is a process flow of a system for metal purification and recovery from a liquid stream with electrochemical cells according to some embodiments; and

[0033] FIG. 4 is a schematic of a housing with a draft angle less than 1 degree according to some embodiments.DETAILED DESCRIPTION

[0034] Electrowinning for metal recovery was established in the 1800s. The standard method has largely remained unchanged; however, the applications have greatly increased. This electrochemical technology can be used to recover metals from wastewater and / or contaminants from process water in a variety of industries, including but not limited to, metal finishing, printed circuit board (PCB) manufacturing, semiconductor manufacturing, mining, lithium-ion battery recycling, medical device manufacturing, and electronics recycling (i.e., E-waste).

[0035] Conventional electrowinning cells encounter several challenges, including but not limited to, low current efficiency, high energy consumption, non-uniform metal deposition, and difficulties harvesting the deposited metal. Cell designs and electrode configurations vary from a design as simple as two rectangular electrodes facing one another and submerged in an open tank to more sophisticated cylindrical cells. In the latter case, a solid cylindrical anode is surrounded by a cylindrical cathode and enclosed in a housing. The cell is filled with a metal-containing feed stream. When a voltage is applied across the electrodes, metal is deposited from the liquid stream onto the interior surface of the cathode to form a solid metal cylinder or tube of the deposited metal. As the metal in the liquid stream is depleted, the deposition rate decreases. When most of the metal is recovered, the tube is harvested by extracting it from thehousing. The deposited metal risks bending, breaking, or warping upon extraction, or worse, remaining stuck inside the housing and unable to be extracted.

[0036] Accordingly, described herein are devices, systems, and methods that address the foregoing challenges. In some embodiments, devices, systems, and methods include a conical metal recovery electrochemical cell comprising a metalbased housing / current collector with a draft angle of less than 1 degree, a metal-based cathode / shim, a metal-based anode, and at least one edge guard surrounding at least one end of the cathode / shim to provide advantages of uniform metal deposition on the entire interior surface of the cathode / shim and ease of extraction of the final metal tube, overcoming the foregoing challenges.

[0037] FIGs. 1A and 1 B illustrate the metal recovery electrochemical cell 100 according to some embodiments. The metal recovery electrochemical cell 100 includes a feed stream inlet 106 and a feed stream outlet 107, shown in FIG. 1 A. FIG. 1 B illustrates an optional handle 109, a top cap 108 (or first cap), a bottom cap 110 (or second cap), a housing 101 (also functioning as a current collector), a cathode shim 102 (also functioning as a shim), an anode 103, and optional edge guards 105, 104 on the top and / or bottom (or first end and / or second end), respectively, of the cathode 102 (shim). The metal recovery electrochemical cell 100 further includes electrical contacts (or electrical connections) and associated wiring to provide the necessary electrical connections to the electrical power supply (not shown).

[0038] In some embodiments, the metal recovery electrochemical cell 100 includes a metal-based housing 101 . Metal-based housing 101 is an outer shell or enclosure of the electrochemical cell, protecting internal components. The metal-based housing 101 can vary in shape and material.

[0039] In one or more embodiments, the housing 101 is cylindrical shaped, conical shaped, contoured, or any combination thereof.

[0040] Housing 101 also serves the function of a current collector. As the current collector, the housing 101 is a conductive component that transfers electrons between the active material and the external circuit and improves charge / discharge efficiency.

[0041] Non-limiting examples for the housing 101 include 304 stainless steel, 316 stainless steel, titanium, copper, aluminum, or a combination thereof. 316 stainlesssteel includes iron plus 16-18% chromium, 10-14% nickel, and 2-3% molybdenum. 304 stainless steel includes iron plus 18-20% chromium, and 8-10.5% nickel. In other embodiments, the housing 101 is a metal sheet. In some embodiments, housing 101 is a 316 stainless steel sheet.

[0042] In some embodiments, the housing 101 has a thickness of at least 0.105 inches. In other embodiments, the housing 101 has a thickness of about 0.059to about 0.140 inches. Yet, in other embodiments, the housing 101 has a thickness of about or in any range between about 0.059, 0.069, 0.079, 0.089, 0.099, 0.109, 0.119, 0.129, 0.139, 0.140, 0.149, 0.159, 0.169, 0.179, 0.189, 0.199, 0.209, 0.219, 0.229, 0.239, 0.249,0.259, 0.269, 0.279, 0.289, 0.299, 0.309, 0.319, 0.329, 0.339, 0.349, 0.359, 0.369,0.379, 0.389, 0.399, 0.409, 0.419, 0.429, 0.439, 0.449, 0.459, 0.469, 0.479, 0.489,0.499, and 0.500 inches.

[0043] In some embodiments, as shown in FIG. 4, the electrochemical device 100 includes a housing 101 with a draft angle 401 . In embodiments, the draft angle 401 is less than 1 degree. In other embodiments, the metal recovery electrochemical cell 100 includes a housing 101 that has a conical shape, with an inner diameter of a first end being different than an inner diameter of a second end.

[0044] As used herein, reference to the “draft angle” with respect to the housing or cathode means the angle between a vertical centerline 405 of the housing or cathode and an adjacent vertical side of the housing or cathode, when both are extrapolated to form an angle. When used in reference to the housing, the draft angle is an angle between the vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle. When used in reference to the cathode, the draft angle is an angle between the vertical centerline of the cathode and an adjacent vertical side of the cathode, when both are extrapolated to form an angle.

[0045] A draft angle is a taper applied to the vertical walls of a mold, which allows for easier release / removal / extraction of the plated metal part from the shim and housing, and for the finished metal tube (housing or cathode) in the instant application. In conventional injection molding and die casting methods, molten material, often metal, is disposed into a mold, also often metal, to fabricate parts. For these applications, asmall draft angle of about 1 .5 to 2 degrees is generally used for metal-on-metal molding functions, and typically, 3 degrees is used to ensure the mold can separate properly.

[0046] In contrast to these conventional processes, for electrowinning used in the instant application, the draft angle need only be large enough to not require a crane for part removal and is therefore less than 1 degree. A minimal amount of force can then be used to extract the finished metal tube.

[0047] Electroforming is another process that can be used to fabricate metal parts. Electroforming is a metal forming process that uses electrodeposition to form or grow metal parts onto a model, known as a mandrel. The purpose of electroforming is to fabricate a specific part, not to recover a metal. In contrast to electrowinning, electroformers would not use a draft angle because it would mar the surface of the part, unlike the instant application, where the draft angle is critical for extraction of the finished metal tube.

[0048] In some embodiments, the draft angle 401 of the housing 101 is about 0.01 to about 1 degree. In other embodiments, the draft angle 401 of the housing 101 is about 0.2 to about 0.8 degree. In embodiments, the housing 101 has a draft angle of about 0.15 to about 0.60 degrees. Still yet, in other embodiments, the draft angle 401 of the housing 101 is about or in any range between about 0.01 , 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1 .00 degree.

[0049] In one or more embodiments, the metal-based housing 101 has a conical shape and a draft angle of about 0.01 to about 1 degree, with the draft angle of the metal-based housing being an angle between the vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle.

[0050] In some embodiments, the metal-based housing 101 has a cylindrical shape and a draft angle of about 0 degree, with the draft angle of the metal-based housing being an angle between the vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle.

[0051] FIG. 4 illustrates housing 101 with a draft angle 401 less than 1 degree according to some embodiments. The metal recovery electrochemical cell 100 includes a conical housing 101 that is 2 feet in height 402 with inner diameters at the top 403 and bottom 404 being different, and in certain embodiments, being 6.35 inches and 5.95 inches, respectively, yielding a cone half angle (CHA) of 0.48 degrees. The CHA corresponds to the draft angle 401 . In one or more embodiments, the draft angle 401 of the housing 101 is at least 0.48 degrees.

[0052] In one or more embodiments, the housing 101 has a height 402 of about 3 feet with inner diameters at the top 403 (first end) and bottom 404 (second end) being different, and in certain embodiments, being 6.35 inches and 5.95 inches, respectively, yielding a cone half angle (CHA) of 0.32 degrees. The CHA corresponds to the draft angle 401 . In one or more embodiments, the draft angle 401 of the housing 101 is 0.32 degrees.

[0053] In some embodiments, the housing 101 has a height 402 of about 1 to about 4 feet. In some embodiments, the housing 101 has a height 402 about or in any range between about 1 .0, 1 .1 , 1 .2, 1 .3, 1 .4, 1 .5, 1 .6, 1 .7, 1 .8, 1 .9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1 , 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, and 4.0 feet.

[0054] In other embodiments, the housing 101 has an inner diameter at the top 403 (first end) of about 4 to about 8 inches. In other embodiments, the housing 101 has an inner diameter at the top 403 (first end) of about or in any range between about 4.0,4.1 . 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0,6.1 . 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1 , 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, and 8.0 inches.

[0055] In some embodiments, the housing 101 has an inner diameter at the bottom 404 (second end) of about 3.8 to about 7.8 inches. Yet, in other embodiments, the housing 101 has an inner diameter at the bottom 404 (second end) about or in any range between about 3.8 4.0, 4.1 , 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1 , 5.2, 5.3,5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1 , 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1 , 7.2, 7.3,7.4, 7.5, 7.6, 7.7, and 7.8 inches.

[0056] In some embodiments, the cathode 102 within the housing 101 also serves as a shim, and is also referred to herein as a mandrel / starter sheet. In one ormore embodiments, the housing 101 is cylindrical shaped, conical shaped, contoured, or any combination thereof.

[0057] The cathode 102 is placed on the inner wall of housing 101 and makes direct contact with the inner wall of the housing 101 , such that there is no space between the inner wall of the housing 101 and the cathode 102. The cathode 102 is in a form of a metal sheet, a foil sheet, a mesh sheet, a metal rod, and / or a metal tube.

[0058] Non-limiting examples of materials for the metal cathode 102 include one or more conductive metals, for example, aluminum, copper, graphite, titanium, 316 stainless steel, 304 stainless steel, or a combination thereof. The metal cathode 102 is a solid (i.e., non-porous) 316 stainless steel sheet in some embodiments.

[0059] In one or more embodiments, the metal cathode 102 includes a metal with a conductivity range of about 1 .0 x 106to about 6.5 x 107S / m, as measured by ASTM E1004 test method at room temperature. In other embodiments, the metal cathode 102 includes a metal with a conductivity range of about or in any range between about 1.0 x 106, 2.5 x 106, 4.0 x 106, 5.5 x 106, 7.0 x 106, 9.0 x 106, 1 .2 x 107, 1 .6 x 107, 2.1 x 107, 2.7 x 107, 3.4 x 107, 4.2 x 107, 5.1 x 107, 5.8 x 107, and about 6.5 x 107S / m, as measured by ASTM E1004 test method at room temperature.

[0060] In some embodiments, the metal cathode 102 includes a metal with a tensile strength range of about 20,000 to about 95,000 pounds per square inch (PSI), as determined by the ASTM E8 standard test method for tension testing of metallic materials. In other embodiments, the metal cathode 102 includes a metal with a tensile strength range of about or in any range between about 20,000; 25,000; 30,000; 35,000; 40,000; 45,000; 50,000; 55,000; 60,000; 65,000; 70,000; 75,000; 80,000; 82,500;85,000; 87,500; 90,000; 92,500; and about 95,000 PSI , as determined by the ASTM E8 standard test method for tension testing of metallic materials.

[0061] In one or more embodiments, the cathode 102 has a draft angle of about 0.01 to about 1 degree. In other embodiments, the cathode 102 has a draft angle of about 0.2 to about 0.8 degree. In embodiments, the cathode 102 has a draft angle of about 0.15 to about 0.60 degrees. Still yet, in other embodiments, the cathode 102 has a draft angle of about or in any range between about 0.01 , 0.05, 0.10, 0.15, 0.20, 0.25,0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00 degree.

[0062] In one or more embodiments, the draft angle 401 of the cathode 102 is at least 0.48 degrees. In some embodiments, the metal-based cathode draft angle is about 0.01 to about 1 degree.

[0063] In one or more embodiments, the cathode 102 is longer than the housing 101 , providing overhang at the top (first end) and bottom (second end) of the housing. In some embodiments, the cathode 102 is about 2 to about 10 inches longer than the length of the housing 101 itself, providing about 1 to about 5 inches of overhang at the top and bottom of the housing 101 . In other embodiments, the cathode 102 is also 6 inches longer than the length of the housing 101 itself, providing 3 inches of overhang at the top and bottom of the housing 101 . In other embodiments, the cathode 102 is also about 4.5 inches longer than the length of the housing 101 itself, providing about 2.25 inches of overhang at the top and bottom of the housing 101 . In one or more embodiments, the cathode 102 is longer than the length of the housing 101 by about or in any range between about 2, 3, 4, 5, 6, 7, 8, 9, and 10 inches, providing an overhang at the top and bottom of the housing 101 that is about or in any range ween about 1 , 2, 3, 4, and 5 inches.

[0064] In some embodiments, the cathode 102 has a thickness of at least 0.024 inches. In one or more embodiments, the cathode 102 has a thickness of about 0.001 to about 0.06 inches. In other embodiments, the cathode 102 has a thickness of about or in any range between about 0.001 , 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011 , 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021 , 0.022, 0.023, 0.024, 0.025, 0.026, 0.027, 0.028, 0.029, 0.030, 0.031 , 0.032, 0.033, 0.034, 0.035, 0.036, 0.037, 0.038, 0.039, 0.040, 0.041 , 0.042, 0.043, 0.044, 0.045, 0.046, 0.047, 0.048, 0.049, 0.050, 0.051 , 0.052, 0.053, 0.054, 0.055, 0.056, 0.057, 0.058, 0.059, and 0.060 inches.

[0065] In some embodiments, the cathode 102 includes a plurality of holes close to the top (first end), which are used to provide grips to an extraction tool that is used to remove the final plated metal cathode tube after metal recovery. In one or more embodiments, the plurality of holes (e.g., two or more holes) are arranged within about0.5 to about 6 inches from the top (first end) of the cathode 102. In other embodiments, the extraction tool includes hooks that fit into the holes in the cathode 102 and a handle to apply an upward force to remove the cathode tube from the housing 101 .

[0066] FIG. 2A is a schematic of an edge guard 105 (see also FIG. 1 B) used in a metal recovery electrochemical cell 100 according to some embodiments. The edge guard 105 is a cylindrical or conical protective covering applied to one or more ends (first end, second end, or both first and second ends) or edges of the cathode 102. In one or more embodiments, the top (first end) of the cathode 102 is covered with a cylindrical edge guard 105 to prevent overgrowth of the metal being deposited behind the cathode 102, while also flaring out the terminal end of the cathode 102 to provide close and direct contact with the housing 101 .

[0067] In other embodiments, the bottom (second end) of the cathode 102 is covered with a cylindrical edge guard 104. Edge guard 104 may be a separate component like edge guard 105 in one or more embodiments. In some embodiments, the edge guard 104 is a contiguous part of the bottom cap 110 or the housing 101 , as shown in FIGs. 2B, 2C, 2D. The edge guard 104 is a cylindrical or conical protective covering applied to one or more ends (first, second end, or both first and second ends) or edges of the cathode 102 (also functioning as a shim). In one or more embodiments, the bottom (second end) of the cathode 102 is covered with a cylindrical edge guard 104 within the bottom cap 110 to prevent overgrowth of the metal being deposited behind the cathode 102, while also flaring out the terminal end of the cathode 102 to provide close and direct contact with the housing 101 .

[0068] The edge guard 104 of the bottom cap 110 includes an internal cylindrical wall 202, a medial cylindrical wall 204, and a circumferential wall 206. The internal cylindrical wall 202 is a central cup that covers and surrounds the anode 103. The internal cylindrical wall 202 limits the active area of the anode 103 to a defined region of the cathode 102 and thereby prevents the cathode 102 (shim) from being stuck and fused to the housing 101 , as well as prevents dendrite formation and shorting that can occur as a result of higher current density at the edges.

[0069] The medial cylindrical wall 204 covers and surrounds the cathode 102. The medial cylindrical wall 204 blocks and prevents metal overgrowth on the bottomedge of the cathode 102 (shim). Without the medial cylindrical wall 204 of the edge guard 104, the cathode 102 (shim) becomes attached to the housing 101 due to the metal overgrowth on the bottom edge, causing the cathode 102 (shim) to remain fused inside the housing 101 and thereby difficult to remove.

[0070] The cathode 102 arranged between the medial cylindrical wall 204 and the circumferential wall 206.

[0071] The edge guard 104 further includes a tangential inlet, or feed stream inlet 106 as shown in FIG. 1 A, which provides vortex fluid flow through the device. The tangential inlet, which allows fluid to flow into the housing, is positioned below the edge guard to direct fluid flow tangentially into the cylindrical I conical device chamber, creating a swirling motion within. The swirling flow prevents stagnant water movement in any given area of the housing 101 and removes the “no slip boundary condition” at the electrode surface, which refers to the zero relative velocity of the aqueous solution immediately adjacent to the electrode is zero relative to the electrode’s surface. As a result, metal deposition is more uniform.

[0072] The bottom cap 110 with the edge guard 104 further includes a housing recess 208 (FIG. 2C), in which the housing is arranged.

[0073] Including the edge guard 104 as a permanent and contiguous part of the cap 110 is advantageous because it does not fall off during device assembly or disassembly. The edge guard 104 portion of the bottom cap 110 prevents recovered metal overgrowth which leads to the collected metal tube to stick to the end cap 110.

[0074] In even other embodiments, the top and bottom (first and second ends) of the cathode 102 are both covered with cylindrical edge guards 105 and 104.

[0075] In some embodiments, the electrochemical cell 100 includes a cylindrical edge guard on the top of the metal-based cathode 102. In other embodiments, the electrochemical cell 100 includes a cylindrical edge guard on the bottom of the metalbased cathode 102.

[0076] In some embodiments, the edge guards 104 and 105 may be made from a polyester, for example, polylactic acid (PLA). In other embodiments, the edge guards 104 and 105 are made from a polymeric material. Non-limiting examples of materials for the edge guards 104 and 105 include acrylonitrile butadiene styrene (ABS),polyvinylidene fluoride (PVDF), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), chlorinated polyvinyl chloride CPVC, polyethylene (PE), polypropylene (PP), thermoplastic polyurethane (TPU), or any combination thereof. In other embodiments, the edge guard 104 may be made from an epoxy coating, vinyl adhesive tape, or electroplating tape.

[0077] The metal recovery electrochemical cell 100 further includes a metalbased anode 103 concentrically located within the housing 101 . The metal-based anode 103 is a cylindrical metal rod in some embodiments.

[0078] In some embodiments, the metal-based anode 103 is a cylindrical metal anode with a diameter of less than 2.875 inches. In other embodiments, the metalbased anode 103 is a cylindrical metal anode with a diameter of about 0.5 to about 5.0 inches. Yet, in other embodiments, the metal-based anode 103 is a cylindrical metal anode with a diameter of about or in any range between about 0.5, 1 .0, 1 .5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 inches.

[0079] The metal-based cathode 102 includes a metallic composition with high enough corrosion resistance to survive a regeneration process in the presence of an oxidizer. Corrosion resistance of the metal-based cathode 102 is measured by linear polarization resistance (LPR) described in ISO 17475 - Corrosion of Metals and Alloys. In some embodiments, the metal-based anode 103 has a corrosion resistance of less than 5 millimeters per year (mmpy), as measured by ISO 17475 - Corrosion of Metals and Alloys. In other embodiments, the metal-based anode 103 has a corrosion resistance of about 0.001 to about 5 millimeters per year (mmpy), as measured by ISO 17475 - Corrosion of Metals and Alloys.

[0080] In some embodiments, the metal-based anode 103 includes a metal substrate with a metal oxide coating. The metal substrate is any coatable metal or metal alloy. The metal substrate can include plates, rods, tubes, wires or knitted wires, and / or expanded meshes of metals or metal alloys. Non-limiting examples of metals for the metal substrate include titanium, tantalum, lead, zirconium, niobium, or any combination or alloy thereof. Non-limiting examples of metal alloys for the metal substrate include titanium nickel alloys, titanium, cobalt alloys, titanium iron alloys, titanium copper alloys,or any combination thereof. According to some embodiments, the metal substrate is a titanium mesh.

[0081] In some embodiments, the metal-based anode 103 is a titanium-coated mixed-metal oxide.

[0082] In one or more embodiments, the metal-based anode 103 includes about 5 grams per square meter (g / m2) of precious metal, but not limited to this amount. For example, the metal-based anode 103 includes less than 2 g / m2, or greater than 8 g / m2of precious metal. In some embodiments, the metal-based anode includes about 1 g / m2to about 10 g / m2precious metal, about 2 g / m2to about 8 g / m2precious metal, about 3 g / m2to about 7 g / m2precious metal, or about 4 g / m2to about 6 g / m2precious metal. Non-limiting examples of the precious metal include platinum, gold, or any combination or alloy thereof.

[0083] In one or more embodiments, the metal oxide coating on the metal substrate includes ruthenium oxide, iridium oxide, titanium oxide, or a combination thereof. Ruthenium chloride (RuCh), iridium chloride (IrCh or FNrCIs), and titanium isopropoxide (Ti{OCH(CHs)2}4), commonly referred to as titanium tetraisopropoxide or TTIP, are combined as precursors in a coating composition, which are deposited on the surface of the metal substrate to form the metal-based anode 103.

[0084] In embodiments, the metal-based anode is a rod structure with a diameter of about 1 to about 6 inches, that forms the core. In one or more embodiments, the metal-based anode is a hollow rod. In other embodiments, the metalbased anode is a solid rod.

[0085] In some embodiments, the metal-based anode has a diameter of about 25 to about 152 millimeters. In other embodiments, the metal-based anode has a diameter of about or in any range between about 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, and 152 millimeters. The size of the metal-based anode can be represented as a ratio of its radius to that of the housing with the following equation:R — r Radius ratio (%) = — - — x 100 R where the radius of the housing is R, and the radius of the metal-based anode is r. In some embodiments, this ratio is about 80%. In other embodiments, the ratio is in anyrange between about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, and 90%.

[0086] In some embodiments, the liquid feed stream enters at the bottom (second end) of the metal recovery electrochemical cell 100 through a tangential inlet 106, generating radial flow as the liquid moves axially up and out of the cell through an outlet 107. However, the liquid flow and cell configuration is not limited to that shown in the figures. In other embodiments, the liquid feed stream enters at the top (first end) of the metal recovery electrochemical cell 100 through a tangential inlet, generating radial flow as the liquid moves axially down and out of the cell through an outlet.

[0087] Non-limiting examples of the liquid feed stream include wastewater and / or process water streams from industries including, but not limited to, metal finishing, printed circuit board (PCB) manufacturing, semiconductor manufacturing, mining, lithium-ion battery recycling, medical device manufacturing, electronics recycling (i.e., E-waste), or any combination thereof.

[0088] The liquid feed stream includes one or more metals of interest for recovery, including but not limited to, copper, zinc, nickel, cobalt, gold, silver, or any combination thereof.

[0089] In some embodiments, the metal of interest in the liquid feed stream that is processed in the metal recovery electrochemical cell is recovered as a solid on the metal-based cathode. A recovered metal, as used herein, means that the metal ions of interest in solution are reduced and electrodeposited or electroplated onto the cathode. The recovered metal is deposited onto the cathode and therefore assumes the shape of the cathode, a tube.

[0090] A voltage is applied across the electrodes, the metal of interest is deposited on the cathode until it is depleted from the feed stream, the housing 101 is opened, and the cathode 102 is removed, for example by an extraction tool. The metal tube is removed, or harvested, from the cathode 102, which serves as a starter sheet, and the cathode 102 is placed back into the housing to be reused.

[0091] Non-limiting examples of metals that can be recovered from the liquid stream include ferrous metals and metal alloys (e.g., stainless steel), non-ferrous metalsand metal alloys (e.g., copper, zinc, nickel, cobalt, tin, chromium, alloys), precious metals (e.g., gold and silver), or any combination thereof.

[0092] When either a current or a voltage is applied to the electrochemical cell, the metal ions in the liquid feed stream are reduced at the cathode (negative electrode) with electrons from the anode (positive electrode). Provided the relationship, i.e., V = IR, either a voltage or current can be applied to control the metal plating. The reduced metal is plated onto the cathode, forming a pure layer of metal. The recovered metal can then be further melted and refined.

[0093] In some embodiments, the applied current is about 100 Amperes (A). In other embodiments, the applied current is about 150 A. In other embodiments, the applied current is about 10 to about 250 A. In some embodiments, the applied current is about or in any range between about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and 250 A. The current efficiency is greater than 95% for all applied currents.

[0094] In other embodiments, the applied voltage is about 0.1 to about 5.0 V. In other embodiments, the applied voltage is about 1 .0 to about 4.0 V. Still yet, in other embodiments, the applied voltage is about or in any range between about 0.1 , 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 .0, 1 .2, 1 .4, 1 .6, 1 .8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, and about 5.0 V.

[0095] In some embodiments, the constant current or voltage is applied (electrowinning) until a final recycle stream concentration of about 3 g / L is achieved. In other embodiments, a final cathode mass or run time is selected. Run times are not limited to 2 hours and may be shorter or longer to achieve the desired outcome.

[0096] In some embodiments, the metal (e.g., copper) is recovered from the liquid feed stream as a solid deposited on the cathode. A current is applied across the electrodes, copper is deposited on the cathode 102 until it is depleted from the feed stream, the housing 101 is opened, and the cathode 102 is removed with the extraction tool. The finished copper tube is then removed, or harvested, from the cathode 102, which serves as a starter sheet, and the cathode 102 is placed back into the housing to be reused.

[0097] In some embodiments, the final recovered metal (e.g., copper) tube has a purity of about 99% to about 100% as measured by optical emission spectroscopy (OES). In other embodiments, the final copper tube has a purity of about, or in any range between about 99.00, 99.10, 99.15, 99.20, 99.25, 99.30, 99.35, 99.40, 99.45, 99.50, 99.55, 99.60, 99.65, 99.70, 99.75, 99.80, 99.85, 99.90, 99.95, and 100.00%.

[0098] In some embodiments, the metal recovery electrochemical cell 100 further includes a separator between the metal-based cathode 102 and the metal-based anode 103 (not shown FIG. 1 ). The separator is a dielectric material that is permeable to ions in solution, but facilitates ion transport across it, preventing physical contact between the electrodes and acts as an electrical insulator. Non-limiting examples of dielectric materials for the separator include cellulosic-based materials, silica-based materials, ion exchange membranes, or any combination thereof.

[0099] In some embodiments, the separator is a planar structure arranged in a cylindrical shape with a thickness of about 1 to about 1000 micrometers. In some embodiments, the separator 103 has a thickness of about 50 to about 250 micrometers. In other embodiments, the separator 103 has a thickness of about, or in any range between about 1 , 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950, 975, and 1000 micrometers.

[0100] In one or more embodiments, the metal recovery electrochemical cell 100 includes a separator between the metal-based anode and the metal-based cathode.

[0101] In some embodiments, the metal recovery electrochemical cell 100 further includes a membrane (not shown), on the metal-based cathode 102 and / or the metal-based anode 103. The membrane may be a cation exchange membrane or an anion exchange membrane, depending on which electrode the membrane is arranged on. The membrane is in a form of a film, a layer, a sheet, a coating, or a combination thereof, and the membrane is arranged on a surface of an electrode or is free-standing. The membrane is on, directly on, or in contact with the electrode in some embodiments. In other embodiments, the membrane surrounds the electrode. In other embodiments, the ion exchange membrane is a bipolar membrane.

[0102] In some embodiments, silver is recovered from the liquid feed stream as a powder.

[0103] FIGs. 3A and 3B are process flows illustrating a metal recovery electrochemical system 300 which includes two electrochemical cells, a metal purification electrochemical cell and a metal recovery electrochemical cell, which recover a metal of interest from a liquid stream according to some embodiments. In some embodiments, the system 300 includes a metal purification electrochemical cell 301 and a metal recovery electrochemical cell 100 arranged downstream from the metal purification electrochemical cell 301 .

[0104] The metal purification electrochemical cell 301 is used to first purify a liquid stream containing dissolved metal(s) to meet discharge compliance or to be reused as process water. A wastewater stream, or Feed Stream, enters and a Purified Stream is formed. A voltage or current is applied to the Feed Stream within the metal purification electrochemical cell 301 , and the target metal is removed from the Feed Stream. The resulting Purified Stream thus includes a reduced concentration of the target metal in solution. The purification process can continue (in batch mode) until the desired final concentration of the metal in the purified stream is achieved, which can be close to zero.

[0105] In some embodiments, a fixed volume of the Feed Stream with the target metal is treated in a single operation cycle, which includes loading the metal purification electrochemical cell 301 with a specific volume of the Feed Stream, running the electrochemical process for a set duration of time, and removing the treated stream once the desired level of metal removal is achieved, which is referred to as batch mode. The removed metal ions from the Feed Stream accumulate on the surface of the carbon-based electrode from being electroplated or reduced following the application of the voltage or current, and the Purified Stream is formed. As shown in FIG. 3A, the Feed Stream enters the metal purification electrochemical cell 301 , and a Concentrated Stream exits. The Feed Stream is the aqueous stream to be treated, such as a wastewater or other aqueous stream with one or more target metals at a first concentration. Initially, a Purified Stream is formed in the metal purification electrochemical cell 301 , which is formed into a Concentrated Stream by a regenerationprocess described below, which exits. The Purified Stream includes a lower concentration of the one or more target metals (second concentration) in solution.

[0106] In order to form the Concentrated Stream in the metal purification electrochemical cell 301 , the accumulated metal on the carbon-based electrode is desorbed into a regeneration solution in a regeneration process. The regeneration process includes electrochemical desorption and acid-assisted dissolution. A regeneration solution including an acid is flowed into electrochemical cell via the Regeneration Stream (see FIG. 3A). The regeneration solution includes an acid and optionally an oxidizing agent. The Regeneration Stream is flushed through the system by backflushing or reversing the flow direction relative to the flow used to remove the metal from the Feed Stream. A reverse or negative potential, in the form of current or voltage, is applied, inducing electrostatic repulsion of adsorbed metal ions on the carbon-based electrode. The regeneration solution also reactivates the electrode surface. The Concentrated Stream that results includes the concentrated metal removed from the Feed Stream in the acidic Regeneration Stream.

[0107] In some embodiments, the Concentrated Stream includes a concentrated metal and a strong acid. Non-limiting examples of strong acids include sulfuric acid (H2SO4), hydrochloric acid (HCI), nitric acid (HNO3), hydrobromic acid (HBr), hydroiodic acid (HI), perchloric acid (HCIO4), and chloric acid (HCIO3).

[0108] The metal recovery electrochemical cell 100 is subsequently used to recapture the metal that was removed by the metal purification electrochemical cell 301 . Rather than disposing of the spent electrodes, the metal can be recycled and re-used. As described above, the Concentrated Stream enters the metal recovery electrochemical cell 100 and a solid metal tube of Recovered Metal is formed, as described above.

[0109] In some embodiments, each of the systems 300 in FIGs. 3A and 3B includes a regeneration tank 302 arranged between the metal purification electrochemical cell 301 and the metal recovery electrochemical cell 100. The regeneration tank 302 restores or regenerates the Concentrated Stream, initially formed in the metal purification electrochemical cell 301 , by removing impurities or rebalancing the chemical composition.

[0110] Initially, the regeneration tank 302 contains the regeneration solution. The regeneration solution includes a strong acid. Non-limiting examples of strong acids include sulfuric acid (H2SO4), hydrochloric acid (HCI), nitric acid (HNO3), hydrobromic acid (HBr), hydroiodic acid (HI), perchloric acid (HCIO4), and chloric acid (HCIO3).

[0111] As the regeneration solution in the regeneration tank is periodically back- flushed through the carbon-based electrode in the metal purification electrochemical cell 301 , the concentrated metal collects in the regeneration tank. The Concentrated Stream flows between the two electrochemical cells.

[0112] Non-limiting examples of materials for the regeneration tank 302 include polypropylene (PP) or polyethylene (PE).

[0113] In some embodiments, the Feed Stream containing dissolved metal(s) is first treated with the metal purification electrochemical cell 301 to produce a Purified Stream with decreased metal(s) concentration. A regeneration solution is circulated in a Regeneration Stream, in a batch mode operation, from the regeneration tank 302 to remove metal(s) from the electrode surfaces to form a Concentrated Stream of metal(s) as shown in FIG. 3A. The Concentrated Stream then flows into the metal recovery electrochemical cell 100 and is circulated in a Recycle Stream, in a batch mode operation, to produce a metal tube as shown in FIG. 3B.

[0114] The metal purification electrochemical cell 301 further includes electrical contacts (or electrical connections) and associated wiring to provide the necessary electrical connections to the electrical power supply (not shown). The power supply is used to control the applied voltage for both electrochemical cells 301 and 100.

[0115] In some embodiments, the system 300 further includes a storage tank, a pump, and a filter upstream of the metal purification electrochemical cell 301 . The storage tank may be used to hold the feed stream before treatment, the pump is used to flow the feed stream through the various stages of treatment, and the filter removes any particulates, peroxide, or other contaminants before treatment.

[0116] In some embodiments, the metal purification electrochemical cell 301 includes a stack of a plurality of cathodes and anodes, each made of different materials and having different properties. In one or more embodiments, the metal purificationelectrochemical cell 301 includes at least one carbon-based electrode (i.e. , an anode or cathode), and at least one metal-based cathode (i.e., an anode or cathode).

[0117] In some embodiments, metal purification electrochemical cell 301 includes an asymmetric electrode configuration, including at least one carbon-based (i.e., carbonaceous) cathode, and at least one non-carbon anode, or in particular, a metal-based (i.e., metal-containing) anode. In some embodiments, the metal-based anode includes a metal substrate with a metal oxide coating as described above. In other embodiments, the electrochemical cell further includes a membrane on the carbon-based cathode and / or on the metal-based anode. The membrane may be a cation exchange membrane or an anion exchange membrane, depending on which electrode the membrane is arranged on. The membrane is in a form of a film, a layer, a sheet, a coating, or a combination thereof, and the membrane is arranged on a surface of an electrode (thus, the metal-based anode and / or the carbon-based cathode) or is free-standing. The membrane is on, directly on, or in contact with the electrode in some embodiments. In other embodiments, the membrane surrounds the electrode. In other embodiments, the ion exchange membrane is a bipolar membrane.

[0118] In some embodiments, metal purification electrochemical cell 301 includes a carbon-based cathode surrounding a metal-based anode and a separator arranged between the metal-based anode and the carbon-based cathode. In embodiments, the electrochemical cell further includes either one of: a conductive cathode current collector housing on the carbon-based cathode or a non-conductive cathode current collector housing on the carbon-based cathode. The conductive cathode current collector housing includes at least one inlet and outlet for the liquid stream, and a metal shim arranged between the carbon-based cathode and the conductive cathode current collector housing. The non-conductive cathode current collector housing includes at least one inlet and outlet for the liquid stream, and a metal shim arranged between the carbonaceous cathode and the non-conductive cathode current collector housing.

[0119] In some embodiments, metal purification electrochemical cell 301 further includes one or more optional current collectors attached to or in contact with one or both of the carbon-based cathode and the metal-based anode. The current collectorsare solid or porous materials. Non-limiting examples of the current collectors are films, layers, metal sheets, foil sheets, or mesh sheets. Non-limiting examples of materials for the current collectors for the carbon-based cathode include graphite, titanium, stainless steel, or a combination thereof. Non-limiting examples of materials of current collectors for the metal-based anode include graphite, titanium, stainless steel, aluminum, copper, nickel, or a combination thereof. In some embodiments, the current collector is a planar structure with a thickness of about 0.01 to about 500 millimeters. In some embodiments, the current collector has a thickness of about 0.1 to about 0.4 millimeters.

[0120] In one or more embodiments, metal purification electrochemical cell 301 further includes a separator arranged between the carbon-based cathode and the metal-based anode. The separator is a dielectric material and prevents physical and electrical contact between the electrodes. Non-limiting examples of dielectric materials for the separator include polymeric materials, cellulosic-based materials, silica-based materials, or any combination thereof. In some embodiments, the separator includes polyethylene. In some embodiments, the separator is a planar structure with a thickness of about 1 to about 5000 micrometers. In some embodiments, the separator has a thickness of about 50 to about 250 micrometers.

[0121] The at least one carbon-based cathode is a carbon-based material. In some embodiments, the at least one carbon-based cathode consists of carbon. In other embodiments, the at least one carbon-based cathode consists essentially of carbon. Non-limiting examples of the carbon-based material include a woven carbon cloth, a carbon film, or a non-woven (e.g. carbon felts, carbon aerogels, etc.), an activated carbon material, or any combination thereof. Carbon cloths are woven, conductive, porous materials that either consist of or consist essentially of carbon. Woven cloths are textiles formed by weaving.

[0122] In some embodiments, the woven cloths have a high surface area of about 700 to about 2300 square meters per gram. In other embodiments, the woven cloths have a high surface area of about 1200 to about 2300 square meters per gram. In other embodiments, the woven cloths have a low surface area of about 0.1 to about 5 square meters per gram.

[0123] Carbon felts are non-woven porous materials that consist of or consist essentially of carbon. In some embodiments, the carbon felts are activated carbon felts. In other embodiments, the carbon felts are thermally treated or surface oxidized carbon felts. In some embodiments, the carbon felt has a low surface area of less than 5 square meters per gram. In some embodiments, the carbon felt has a high surface area of about 1200 to about 2300 square meters per gram.

[0124] Carbon films are carbon composites that consists of or consists essentially of carbon particles and a carbon binder. In one or more embodiments, the carbon film is an activated carbon film that is microporous and includes a binder. Nonlimiting examples of the binder of the activated carbon film include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium alginate, sodiumcarboxymethyl cellulose, an ion exchange polymer, or a combination thereof. In some embodiments, the activated carbon film has a surface area of about 1200 to about 1400 square meters per gram.

[0125] In some embodiments, a metal recovery electrochemical cell comprises a metal-based anode; a metal-based cathode; and a metal-based housing with a conical shape and a draft angle of about 0.01 to about 1 degree, the draft angle of the metalbased housing being an angle between a vertical centerline of the metal-based housing and an adjacent vertical side of the metal-based housing, when both are extrapolated to form an angle.

[0126] In other embodiments, wherein the draft angle of the metal-based housing is about 0.15 to about 0.60 degrees; an inner diameter of a first end of the metal-based housing is different than an inner diameter of a second end of the metalbased housing; or a combination thereof.

[0127] In one or more embodiments, the metal-based cathode further comprises a draft angle that is an angle between a vertical centerline of the metal-based cathode and an adjacent vertical side of the metal-based cathode, when both are extrapolated to form an angle, wherein optionally, the draft angle of the metal-based cathode is about 0.01 to about 1 degree, or about 0.15 to about 0.60 degrees.

[0128] In some embodiments, the metal recovery electrochemical cell further comprises a cylindrical edge guard on a top of the metal-based cathode, or a cylindrical edge guard on a bottom of the metal-based cathode.

[0129] In other embodiments, the metal-based anode is a titanium-coated mixed-metal oxide, the metal-based cathode is a 316 stainless steel sheet, and / or the metal-based housing comprises a 316 stainless steel.

[0130] In one or more embodiments, the metal recovery electrochemical cell further comprises a separator between the metal-based anode and the metal-based cathode, a membrane arranged on the metal-based anode and the metal-based cathode, or a combination thereof.

[0131] In some embodiments, the metal-based cathode comprises a metal with a linear polarization resistance (LPR) of less than 0.1 millimeters per year (mmpy), as measured by ISO 17475 - Corrosion of Metals and Alloys.

[0132] In one or more embodiments, a metal recovery electrochemical system comprises a metal purification electrochemical cell comprising at least one carbonbased electrode and at least one metal-based electrode; the metal recovery electrochemical cell; wherein the metal recovery electrochemical cell is arranged downstream from the metal purification electrochemical cell; and optionally, a regeneration tank arranged between the metal purification electrochemical cell and the metal recovery electrochemical cell.

[0133] In some embodiments, at least one carbon-based electrode is a carbon felt, a woven carbon cloth, a carbon film, a non-woven, or an activated carbon material; and / or the at least one metal-based electrode comprises a metal with one or more metal oxides arranged on the metal.

[0134] In other embodiments, a metal recovery electrochemical cell includes a metal-based anode; a metal-based cathode surrounding the metal-based anode; a cap covering an end of the metal-based cathode, the cap comprising a cylindrical edge guard with an internal cylindrical wall, a medial cylindrical wall, and a circumferential wall; and optionally, a metal-based housing with a cylindrical shape.EXAMPLES

[0135] An electrowinning trial was conducted on a liquid stream containing copper. A 316 SS cathode and a mixed metal oxide (MMO) anode were used in a two- foot high metal recovery electrochemical cell. A constant current of 75 A (2.6 volts (V)) was applied for 2 hours, with a flow rate of 10 gallons-per-minute (gpm). The final recovered copper mass was 4.073 kilograms (kg), equivalent to approximately 97% of the theoretical maximum copper of 4.31 kg (or 97% current efficiency).

[0136] An electrowinning trial was conducted on a liquid stream containing copper. A 316 SS cathode and a MMO anode were used in a one-foot high metal recovery electrochemical cell. A constant current of 40 A (3.05-3.2 V) was applied for 24 hours, with a flow rate of 10 gpm. The final recovered copper mass was 1112 grams (g), equivalent to approximately 98% of the theoretical maximum copper of 1136 g (or 98% current efficiency).

[0137] An electrowinning trial was conducted on a liquid stream containing copper. A 316 SS cathode and a MMO anode were used in a two-foot high metal recovery electrochemical cell. A constant current of 115 A (3.6 V) was applied for 24 hours, with a flow rate of 10 gpm. The final recovered copper mass was 3262 g, equivalent to approximately 96% of the theoretical maximum copper of 3403 g (or 96% current efficiency).

[0138] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0139] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt.%, or, more specifically, 5 wt.% to 20 wt.%”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt.% to 25 wt.%,” etc.). “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do notdenote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and / or” unless clearly stated otherwise. As used herein, the terms “comprising” “including,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, i.e., to mean “including” but not limited to, unless otherwise noted. “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ± 10% or ± 5% of the stated value. The use of any and all examples, or exemplary language (e.g., “such as”), is intended merely to better illustrate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention as used herein.

[0140] Reference throughout the specification to “an aspect”, “an embodiment”, and so forth, means that a particular element described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. A “combination thereof” is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property.

[0141] Various embodiments of the present invention are described herein with reference to the related drawings. Alternative embodiments can be devised without departing from the scope of this invention. Although various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings, persons skilled in the art will recognize that many of the positional relationships described herein are orientation-independent when the described functionality is maintained even though the orientation is changed. These connections and / or positional relationships, unless specified otherwise, can be direct orindirect, and the present invention is not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship. As an example of an indirect positional relationship, references in the present description to forming layer “A” over layer “B” include situations in which one or more intermediate layers (e.g., layer “C”) is between layer “A” and layer “B” as long as the relevant characteristics and functionalities of layer “A” and layer “B” are not substantially changed by the intermediate layer(s).

[0142] The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0143] Additionally, the term “exemplary” is used herein to mean “serving as an example, instance or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “at least one” and “one or more” are understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms “a plurality” are understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc. The term “connection” can include an indirect “connection” and a direct “connection.”

[0144] References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may or may not include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature,structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0145] For purposes of the description hereinafter, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” and derivatives thereof shall relate to the described structures and methods, as oriented in the drawing figures. The terms “overlying,” “atop,” “on top,” “positioned on” or “positioned atop” mean that a first element, such as a first structure, is present on a second element, such as a second structure, wherein intervening elements such as an interface structure can be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary conducting, insulating or semiconductor layers at the interface of the two elements.

[0146] The terms “about,” “substantially,” “approximately,” and variations thereof, are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ± 8% or 5%, or 2% of a given value.

[0147] The flowchart and block diagrams in the Figures illustrate possible implementations of fabrication and / or operation methods according to various embodiments of the present invention. Various functions / operations of the method are represented in the flow diagram by blocks. In some alternative implementations, the functions noted in the blocks can occur out of the order noted in the Figures. For example, two blocks shown in succession can, in fact, be executed substantially concurrently, or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved.

[0148] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

[0149] While the preferred embodiments to the invention have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.

Claims

CLAIMSWhat is claimed is:1 . A metal recovery electrochemical cell comprising: a metal-based anode; a metal-based cathode; and a metal-based housing with a conical shape and a draft angle of about 0.01 to about 1 degree, the draft angle of the metal-based housing being an angle between a vertical centerline of the metal-based housing and an adjacent vertical side of the metalbased housing, when both are extrapolated to form an angle.

2. The metal recovery electrochemical cell of claim 1 , wherein the draft angle of the metal-based housing is about 0.15 to about 0.60 degrees; an inner diameter of a first end of the metal-based housing is different than an inner diameter of a second end of the metal-based housing; or a combination thereof.

3. The metal recovery electrochemical cell of claim 1 , wherein the metal-based cathode further comprises a draft angle that is an angle between a vertical centerline of the metal-based cathode and an adjacent vertical side of the metal-based cathode, when both are extrapolated to form an angle, wherein optionally, the draft angle of the metal-based cathode is about 0.01 to about 1 degree, or about 0.15 to about 0.60 degrees.

4. The metal recovery electrochemical cell of claim 1 , further comprising a cylindrical edge guard on a top of the metal-based cathode, or a cylindrical edge guard on a bottom of the metal-based cathode.

5. The metal recovery electrochemical cell of claim 1 , wherein the metal-based anode is a titanium-coated mixed-metal oxide, the metal-based cathode is a 316 stainless steel sheet, and / or the metal-based housing comprises a 316 stainless steel.

6. The metal recovery electrochemical cell of claim 1 , further comprising a separator between the metal-based anode and the metal-based cathode, a membrane arranged on the metal-based anode and the metal-based cathode, or a combination thereof.

7. The metal recovery electrochemical cell of claim 1 , wherein the metal-based cathode comprises a metal with a linear polarization resistance (LPR) of less than 0.1millimeters per year (mmpy), as measured by ISO 17475 - Corrosion of Metals and Alloys.

8. A metal recovery electrochemical system comprising: a metal purification electrochemical cell comprising at least one carbon-based electrode and at least one metal-based electrode; the metal recovery electrochemical cell of claim 1 ; wherein the metal recovery electrochemical cell is arranged downstream from the metal purification electrochemical cell; and optionally, a regeneration tank arranged between the metal purification electrochemical cell and the metal recovery electrochemical cell.

9. The system of claim 8, wherein the at least one carbon-based electrode is a carbon felt, a woven carbon cloth, a carbon film, a non-woven, or an activated carbon material; and / or the at least one metal-based electrode comprises a metal with one or more metal oxides arranged on the metal.

10. A metal recovery electrochemical cell comprising: a metal-based anode; a metal-based cathode surrounding the metal-based anode; a cap covering an end of the metal-based cathode, the cap comprising a cylindrical edge guard with an internal cylindrical wall, a medial cylindrical wall, and a circumferential wall; and optionally, a metal-based housing with a cylindrical shape.

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