Novel Systems And Methods Of Reductive-Acid Leaching Of Spent Battery Electrodes To Recover Valuable Materials

Abstract

The present invention describes systems and methods of a novel hydrometallurgical process to perform reductive-acid leaching and separation of constituent compounds from solid material generated from the electrodes of lithium-ion batteries, or other source material containing target high-value materials. The process method involves the initial reductive-acid leaching with sulfur dioxide and sulfuric acid of the source material which may be performed in a single or a multi-step embodiment. In a single-step embodiment, the reductive-acid leaching results in two outlet streams, a leachate solution and a bulk solid, such as graphite. In a two-step embodiment, a dilute reductive-acid leaching results in a lithium brine that may be bled as a product stream. The resulting liquor, or leachate, can be subjected to precipitation and oxidation steps to remove other compounds except, for example lithium, cobalt, and nickel. Electrowinning may then be used to separate and recover cobalt and nickel alloys among other high value compounds from a lithium brine.

Claims

1. A method of extracting metals comprising the steps: depositing a first quantity of black mass derived from processed lithium-ion batteries in an acid-reduction reactor; reductive-acid leaching said black mass through the introduction of an acid solution causing the production of: a mother leachate containing a mixture of solubilized metals; a quantity of bulk solid material; increasing the pH of the mother leachate causing said solubilized metals to form metal hydroxides and further precipitating said metal hydroxides from the leachate; oxidizing aqueous manganese (Mn) present in the leachate forming insoluble manganese dioxide (MnO.sub.2) and precipitating said MnO.sub.2 from the leachate; electrowinning the leachate to form a quantity of cobalt/nickel alloy and extracting the cobalt/nickel alloy; increasing the pH of the leachate precipitating cobalt, nickel and other trace metals remaining in the leachate as hydroxides; generating a Lithium (Li) bleed stream; and extracting said Li Brine from the bleed stream, or recycling said Li Brine back into said acid-reduction reactor with an additional quantity of black mass.

2-61. (canceled)

62. A method of extracting metal alloys from a source material comprising the steps: depositing a first quantity of source material containing lithium, cobalt, nickel, manganese or graphite in an acid-reduction reactor; reductive-acid leaching said source material through the introduction of an acid solution, wherein said acid-reduction reactor maintains a pH of at least 6, causing the production of a first Lithium (Li) brine to be further concentrated through additional application of reductive-acid leaching steps, and wherein said reductive-acid leaching said source material through the introduction of an acid solution causing the production of: a mother leachate containing a mixture of solubilized metals; a quantity of bulk solid material; increasing the pH of the mother leachate causing said solubilized metals to form metal hydroxides and further precipitating said metal hydroxides from the leachate; oxidizing aqueous manganese (Mn) present in the leachate forming insoluble manganese dioxide (MnO.sub.2) and precipitating said MnO.sub.2 from the leachate; electrowinning the leachate to form a quantity of cobalt/nickel alloy and extracting the cobalt/nickel alloy; increasing the pH of the leachate precipitating cobalt, nickel and other trace metals remaining in the leachate as hydroxides; generating a Lithium (Li) bleed stream; and extracting said Li Brine from the bleed stream, or recycling said Li Brine back into said acid-reduction reactor with an additional quantity of black mass.

63-65. (canceled)

66. A method of extracting metal from a feed material comprising the steps in order: depositing a first quantity of nickel and/or cobalt rich feed material into an acid-reduction reactor; reductive-acid leaching said feed through the introduction of an acid and reducing agent solution causing the production of: a mother leachate containing a mixture of solubilized metals; a quantity of bulk solid material; increasing the pH of the mother leachate causing some of the impurity metals to form metal hydroxides and further separating said metal hydroxides from the leachate; oxidizing aqueous manganese (Mn) present in the leachate forming insoluble manganese dioxide (MnO.sub.2) and separating said MnO.sub.2 from the leachate; electrowinning the leachate to form a quantity of cobalt/nickel alloy and extracting the cobalt/nickel alloy; increasing the pH of the leachate to precipitate and separate residual cobalt, nickel and other trace metals remaining from the leachate as hydroxides; generating a lithium (Li) brine stream from the leachate

67. The method of claim 66, wherein said acid and reducing agent solution comprises a solution of sulfur dioxide (SO2) and/or a solution sulfuric acid (H.sub.2SO.sub.4), and/or an acid solution generated by said electrowinning step.

68. The method of claim 66, where the feed comprises black mass derived from lithium-ion batteries, a nickel or cobalt rich ore, a mixed hydroxide product (MHP), a raw or intermediate product containing nickel and/or cobalt, or a combination of the same.

69. The method of claim 66, wherein said solubilized metals are selected from the group consisting of: lithium (Li), cobalt (Co), nickel (Ni), and manganese (Mn).

70. The method of claim 67, wherein 0-2 mole of said SO2 is introduced into said acid-reduction reactor for each mole of Co, Ni and Mn in said feed.

71. The method of claim 66, wherein acid-reduction reactor maintains a pH between 1-4 during leaching.

72. The method of claim 66, further comprising the step of controlling the pH of the mother leachate by one or more of the following: recycling downstream produced metal hydroxides to increase or maintain the pH in said acid-reduction reactor; introducing a base compound to increase or maintain the pH in said acid-reduction reactor; and introducing an acid compound to reduce the pH in said acid-reduction reactor; and introducing an additional quantity of feed.

73. The method of claim 66, wherein said step of increasing the pH of the mother leachate compromises increasing the pH of the leachate to between 4-7.

74. The method of claim 66, wherein said step of oxidizing aqueous Mn is performed by an oxidant selected from the group consisting of: oxygen, air, SO.sub.2, ozone, permanganate, or a combination of the same.

75. The method of claim 66, wherein the Mn remaining in said leachate after oxidation is less than 2 g/l but not less than 0.5 g/l.

76. The method of claim 66, wherein said step of oxidizing aqueous Mn occurs prior to the step of precipitating said metal hydroxides from the leachate.

77. The method of claim 66, wherein said step of electrowinning is performed in an electrowinning cell where a bag is configured to separate the anodes and cathodes to concentrate the acid generated at the anode, wherein the concentrated acid solution is recycled into said acid-reduction reactor.

78. The method of claim 66, wherein the stream is recycled back into the process to concentrate said solubilized metals or change the leachate pH.

79. The method of claim 66, further comprising a two-step reductive-acid leach of said feed, wherein said acid-reduction reactor maintains a pH of at least 6, causing selective leaching of lithium producing a second Li brine stream to be further concentrated through application of multiple reductive-acid leaching steps.

80. The method of claim 66, further comprising the step of increasing the pH of the Li brine to precipitate remaining cobalt, nickel and other trace metals as hydroxides.

81. The method of claim 66, wherein said quantity of bulk solid material comprises a quantity of graphite, silicon, and/or other non-solubilized material.

82. The method of claim 81, further comprising the step of purifying said quantity of graphite.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] FIG. 1 displays the generalized process steps and resulting product streams in one embodiment thereof;

[0030] FIG. 2 displays a block diagram of a single reductive leaching step in one embodiment thereof;

[0031] FIG. 3 displays a block diagram of a two reductive leaching steps in one embodiment thereof; and

[0032] FIG. 4 displays a modified process where manganese is oxidized and removed prior to the formation and removal of other hydroxides in one embodiment thereof;

DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention includes a variety of aspects, which may be combined in different ways. The following descriptions are provided to list elements and describe some of the embodiments of the present invention. These elements are listed with initial embodiments; however, it should be understood that they may be combined in any manner and in any number to create additional embodiments. The variously described examples and preferred embodiments should not be construed to limit the present invention to only the explicitly described systems, techniques, and applications. Further, this description should be understood to support and encompass descriptions and claims of all the various embodiments, systems, techniques, methods, devices, and applications with any number of the disclosed elements, with each element alone, and also with any and all various permutations and combinations of all elements in this or any subsequent applications.

[0034] In one preferred embodiment, the invention includes novel systems and methods for the reductive-acid leaching and separation of constituent compounds from solid material generated from the electrodes of lithium-ion batteries (LIB). As shown generally in FIG. 1, in one embodiment the process method involves an initial reductive-acid leaching (101) step with sulfur dioxide and sulfuric acid of a black mass (1) solid which may be performed in a single (101) or a multi-step (101, 101A) embodiment. In a single-step embodiment shown in FIG. 2, the reductive-acid leaching (101) results in two outlet streams, a leachate solution (7) and a bulk solid such as graphite (3). In a two-step embodiment shown in FIG. 3, a dilute reductive-acid leaching (101) result results in a lithium brine (2) that may be bled as a product stream (12). The resulting liquor, or leachate (7), can be subjected to a precipitation (102) step, for example by the formation of hydroxides, and an oxidation (103) step, and preferably a manganese (Mn) oxidation step, to remove other compounds except lithium (Li), cobalt (Co), and nickel (Ni). Electrowinning (104) may then be used to separate and recover Co and Ni (6) from a Li brine. In this process, the acid produced in the electrowinning cell as may be used as primary acid source (13b) for the reductant/acid leaching of the Black Mass (1).

[0035] As noted above, the present invention includes a single and multiple-stage method for the reductive-acid leaching and separation of constituent compounds from solid material generated from the electrodes of lithium-ion batteries. In the first method shown in FIG. 2, single stage reductive-acid leaching (101) step occurs where Li, Co, Ni, and Mn are extracted at the same time. In a second method shown in FIG. 3, a portion of Li is selectively leached in one distinct step and then dissolved with the remaining Li, Co, Ni, Mn extracted in another step. As noted below, the invention include two methods to operate the electrowinning cell, namely a standard flow through cell and anode bags cell to produce a more concentrated acid stream (13b) that may be used as primary acid source for the reductant/acid leaching of the black mass (1).

EXAMPLE 1: SINGLE STATE METAL EXTRACTION

[0036] As generally shown in FIGS. 1-2, in one preferred embodiment a quantity of black mass (1) is mixed with the acid solution (8), which may be the anolyte or electrolyte of the electrowinning (104) step generated from the electrowinning cell (9), and preferably a concentrated acid stream (13b) generated by the electrowinning (104) step generated from the electrowinning cell (9). As shown in FIG. 2, an acid solution is introduced into an acid-reduction reactor (10) until a pH of between 1-4 is achieved to solubilize the Li, Co, Mn, and Ni in the reactor.

[0037] In one embodiment, 0.25-2 mole of SO2 may be added to the acid-reduction reactor (10) for each mole of Co, Ni and Mn in the black mass (2). Preferably, the end pH when 0.25-2 mole of SO2 to 1 mole Co, Ni, Mn is added can be between approximately pH 1-4. If the pH drops below 2 upon the addition of 0.25-2 mole SO2, then a base, such as either recycle slurry of Co/Ni hydroxide, or NaOH can be added to hold pH at approximately 2 while remaining SO2 is added. This step may ensure enough reductant is added to the acid-reduction reactor (10) to dissolve the metals. If pH is greater than 4 when SO2 is at 0.25-2 mole SO2 per mole Co, Ni, Mn, then an acid, such as sulfuric acid can be added to the acid-reduction reactor (10) until a pH of approximately 3-4 is reached. This ensures sufficient acid is available to the system to dissolve the target metals.

EXAMPLE 2: TWO-STAGE METAL EXTRACTION

[0038] In one preferred embodiment the invention includes a two-stage process for the reductive-acid leaching and separation of constituent compounds from solid material generated from the electrodes of lithium-ion batteries. As generally shown in FIGS. 1 and 3, in this two-stage process, a portion of Li, generally in the form a Lithium brine (2) is selectively leached from a first quantity of black mass (1) in one distinct step and then dissolved with the remaining Li, Co, Ni, Mn extracted in one or more separate step(s).

[0039] Referring again to FIG. 3, in this two-stage process a quantity of back mass (1) can be mixed with a hydroxide recycle stream (11) from this process in an acid-reduction reactor (10) while a small Lithium bleed stream (12) from the electrowinning loop can be used to control Li levels in the downstream electrowinning loop. SO2 is injected into an acid-reduction reactor (10) to pH of approximately 6 to facilitate the separation and extraction of Li present in the reactor, generally in the form of a Lithium brine (2). Moles of SO2 added to the acid-reduction reactor (10) are tracked and used in the calculation for stage 2 metals extract. Next, the pH is raised to approximately pH 9 to remove Co/Ni and other metals from Li product. The slurry is filtered and solids report to the second stage of the metal extraction process. The filtrate contains clean Li brine (2) for market. To optimize yields, the filtrate can be recycled back to acid-reduction reactor (10) and be mixed with a new quantity of black mass (1) to build Li concentration. The volume of the bleed stream (12) can be adjusted to maintain target product Li concentration.

[0040] Referring again to FIG. 3, solids from lithium brine (2), (also referred to as the Li extract) are mixed in an acid-reduction reactor (10) with the acid solution (13b) generated from the downstream electrowing process, and preferably a concentrated acid-solution (13b) from an anode bag used for electrowinning as described below. SO2 is injected until the combined SO2 from the Li extract (2) and this metals extract is approximately 0.25-2 mole SO2 to 1 mole Ni+Co+Mn. In this embodiment, the end pH when approximately 0.25-2 mole SO2 to 1 mole Co, Ni, Mn is added may be in the pH 1-4 range. If the pH drops below 2 upon the addition of 0.25-2 mole SO2, then a base, such as the recycled downstream slurry of Co/Ni hydroxide, or NaOH is added to hold pH at approximately 2 while remaining SO2 is added. This ensures enough reductant is added to dissolve the metals. If pH is greater than 4 when SO2 is at approximately 0.25-2 mole SO2 per mole Co, Ni, Mn then and acid, such as sulfuric acid is added until pH of approximately 3-4 is reached. This ensures enough acid is available to dissolve the target metals. The slurry produced is filtered and the extracted graphite (3) is washed prior to packaging. Next, the filtrate, generally referred to as the leachate (7) or mother leachate (7), undergoes a solution purification process.

EXAMPLE 3: SOLUTION PURIFICATION

[0041] In one preferred embodiment, the invention may include the downstream precipitation and extraction of certain metals, such as Cu, Fe, and Al from the mother leachate (7). Generally referring to FIG. 2-3, the pH of the Leachate (7) is raised with NaOH or recycle hydroxides (13) to a pH of approximately 6. A target pH, whether 4 or as high as 7 can be determined once the Co/Ni concentrations are selected that optimize cathode quality in electrowinning cell. At 50 g/l Co/Ni optimum pH may be closer to 5.8. At 20 g/l Co/Ni the optimum pH may be around 6.1. Typically, 20-40 g/l range may be preferred and a pH of this step when optimized can be between approximately 5.9 to 6.1. Notably, the optimum pH is where most of the Cu, Fe, and Al are removed with minimal loses of Co/Ni. The solution is filtered with solids going to a Al precipitate wash step and remaining solution going to Manganese precipitation (103) step.

EXAMPLE 4: MANGANESE PRECIPITATION

[0042] In one preferred embodiment, the invention may include the downstream precipitation and extraction of Mn (103), for example as a MnO.sub.2 (5). Generally referring to FIG. 2-3, after the removal of metal hydroxides (4), the solution is transmitted to a Mn precipitation reactor (14), where SO2 and O.sub.2 are added at published ratios to oxidize the Mn++ to its insoluble form of MnO.sub.2. In this step, the process reduces the Mn levels to less than 2 g/l but not less than 0.5 g/l. The electrowinning cell (9) can tolerate this level of Mn and if all or most the Mn is converted to MnO.sub.2 then the oxidant will start oxidizing Co++ to Co+++ and forming Co.sub.2O.sub.3 which is a loss of Co to the MnO.sub.2 product.

[0043] Ignoring the O.sub.2 that is added proportional to SO.sub.2, in this embodiment 1 mole of SO.sub.2 may be required to oxidize 1 mole Mn so the reaction is run at starvation levels of SO.sub.2 to hit the target 1 g/l Mn in the finish solution. Though any level between 0.5 and 2 g/l can be used. Next, the pH is raised to approximately pH 5 with a base, such NaOH or recycled metal hydroxides (4) generated from the process. The leachate solution is filtered and solids go to a MnO.sub.2 wash step while filtrate is passed to the electrowinning (104) step to further remove Co/Ni.

[0044] As noted in FIG. 4, the downstream precipitation and extraction of Mn (103), for example as a MnO.sub.2 (5) can occur upstream prior to the formation and removal of other hydroxides (102).

EXAMPLE 5: ELECTROWINNING

[0045] In one preferred embodiment, the invention may include a downstream electrowinning (104) step configured to remove certain additional metals, such as Co and Ni, for example as a Co/Ni alloy (6). As generally shown in FIGS. 2-3, as part of the single- or two-stage metal extraction process, the electrowinning (104) step may follow a standard flow through cell configuration, as opposed to an alternative anode bag. Using this operating design, the Co/Ni delta may need to be accounted for in the process. A standard operating design Co/Ni delta for a flow through cell is considered to be 5 g/l Co/Ni drop to maintain pH in the cell greater than 2.5 and more typically 3. The lower pH electrolyte can be recycled to the metals extract steps of the inventive process as an acid source (13b). With a flow through cell configuration, the metals extract step may be generally limited to 5 g/l Co/Ni delta.

[0046] In an alternative methods, the inventive process may utilize anode bags configured to perform the electrowinning (104) step. In this embodiment, the anode is surrounded by an anode bag. In one exemplary model, an anode bag produced by Filtaquip™ may be used as a representative device. From this anode bag anolyte can be recovered. Since acid is generated at the anode, the anolyte can contain 50 g/l sulfuric acid or more. In one embodiment, the process may utilize a general accepted anolyte strength of 50 g/l sulfuric acid which will then dissolve 30 g/l Co/Ni. This reduces the size of metal extract step by a factor of 6-30 g/l divided by 5 g/l for flow through cell.

EXAMPLE 5: LITHIUM BLEED

[0047] In one preferred embodiment, the invention may include a lithium bleed stream (12) from the electrowinning loop to control Li levels in the downstream electrowinning loop. Since the metal extract and electrowing cell are in a closed loop, lithium may need to be removed so a bleed stream (12) that is at desired Li extract (2) concentration and at daily lithium production rate is removed each day. The pH can raise to pH 9 to precipitate contained metals. This stream is filtered with the filtrate being the daily lithium product (2) for market and the solids cobalt and nickel hydroxide being used as bases to be recycled back into the process as outlined above.

TABLES

[0048]

TABLE-US-00001 TABLE 1 Representative composition of black mass, mother leachate, and product graphite Black Mass Concentration Extraction Graphite Product Constituent [dry wt %] Efficiency Composition Co 15.8% 99.92% 0.023% Li 3.89% 99.88% 0.008% Mn 9.82% 99.95% 0.009% Ni 12.3% 99.82% 0.038% Al 0.29% 84.21% 0.079% Cu 0.14% 60.17% 0.094% Fe 0.38% 96.80% 0.021% C(gr) 57.0% N/A 99.66% Others 0.35%  96.01%.sup.a 0.064% .sup.aaveraged extraction efficiency

TABLE-US-00002 TABLE 2 Representative composition of the solution after removal of manganese, and other undesired products as well as the solid manganese product. Constituent of Mn Mn-lean Solution Mn Product Removal Step [g/L] [dry wt %] Co 46.667 0.005% Li 24.884 0.005% Mn 1.000 61.84%.sup.a Ni 36.259 0.005% Al 0.000 0.00% Cu 0.0600 0.05% Fe 0.050 3.48% Others 1.611 0.00% .sup.abalance is oxygen

TABLE-US-00003 TABLE 3 Representative composition of the solution in and out of the electrowinning cell as well as the metal alloy product. Constituent of EW Feed EW Discharge Ni/Co Product EW Step [g/L] [g/L] [dry wt %] Co 26.880 10.00 56.13% Li 24.884 24.88 Trace Mn 1.000 1.00 Trace Ni 20.890 7.70 43.61% Al 0.001 0.001 Trace Cu 0.010 0.01 Trae Fe 0.010 0.01 Trace Others 1.611 1.52 <0.25%