Cadmium removal in lithium-ion battery recycling

Abstract

To provide a simplified hydrometallurgical LiB recycling process which efficiently removes impurities, including cadmium (Cd), to ensure production of battery-grade materials.SOLUTION: This method includes removing cadmium (Cd) from a pregnant leach solution before recovering valuable battery metals such as nickel (Ni), manganese (Mn), cobalt (Co), and lithium (Li). The removal of the Cd may be performed by precipitating an insoluble organo-complex by adding an organic compound material to the pregnant leach solution. The organic compound material may include one or more of organosulfur, organothiophosphate, benzothiazole compounds or derivatives, such as dithiophosphinate, dithiophosphate, and mercaptobenzothiazole, respectively.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. Patent Application No. 18 / 323,631, filed May 25, 2023, and a continuation-in-part of U.S. Patent Application No. 17 / 804,337, filed May 27, 2022. Additionally, this application claims priority to U.S. Provisional Patent Application No. 63 / 368,396, filed July 14, 2022, and U.S. Provisional Patent Application No. 63 / 365,422, filed May 27, 2022.

[0002] The entire disclosures of U.S. Patent Application Nos. 18 / 323,631 and 17 / 804,337, and U.S. Provisional Patent Application Nos. 63 / 368,396 and 63 / 365,422 are incorporated herein by reference. [Background technology]

[0003] Lithium-ion batteries (LiBs) are expected to have the greatest growth in several applications, especially in electric vehicles (EVs) in the coming years. The earliest generation of EV batteries are still in use as they typically reach their end of life (EOL) in 10-12 years. With the surge in demand for LiBs in the EV market, disposal of EOL batteries is expected to increase soon. With aggressive regulations on disposal and recovery of used batteries, recycling of LiB waste could provide a significant and reliable supply of valuable metals.

[0004] There are pyrometallurgical methods for processing EOL LiB, with smelting as the core process. Pyrometallurgical methods are disadvantageous in certain respects and present significant obstacles such as high energy consumption, expensive toxic gas disposal, and loss of lithium to slag. Furthermore, the recovered metals are in a form that may not be suitable for battery production, and additional processing may be required to separate the recovered materials into individual metal compounds.

[0005] The present disclosure is directed to a streamlined hydrometallurgical process that significantly overcomes the shortcomings of the prior art. Summary of the Invention

[0006] The present disclosure generally relates to a simplified or uncomplicated hydrometallurgical LiB recycling process that efficiently removes impurities, including cadmium (Cd), to ensure the production of battery-grade materials.

[0007] According to one embodiment of the present disclosure, a method for recovering valuable metals from black mass comprises removing Cd from pregnant leach solution (PLS) and then precipitating and recovering valuable metals from the PLS at a downstream location.

[0008] The present disclosure also relates to a method for recovering valuable metals from Cd-containing black mass, comprising the removal of Cd from the PLS and subsequent precipitation and recovery of valuable metals from the PLS, the valuable metals comprising one or more of nickel (Ni), manganese (Mn), cobalt (Co), and lithium (Li).

[0009] The present disclosure also relates to a method for recovering valuable metals from black mass, comprising removing Cd from the PLS and then precipitating and recovering valuable metals from the PLS downstream of Cd removal. The removal of Cd may include precipitating insoluble organic complexes by adding an organic compound material to the PLS. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a process flow diagram of an example of a streamlined hydrometallurgical process according to the present disclosure. [Diagram 2] FIG. 2 is a more detailed flow diagram for a portion of the process of FIG. [Diagram 3] FIG. 3 is a graph showing the precipitation of Cd using sodium-2-mercaptobenzothiazole (NaMBT) at different dosages, showing the concentration of critical metals remaining in solution at different NaMBT dosages. [Figure 4]FIG. 4 is a graph showing the precipitation of Cd using sodium-2-mercaptobenzothiazole (NaMBT) at different dosages, showing the concentrations of Cd and phosphorus (P) in solution at different NaMBT dosages. [Diagram 5] FIG. 5 is a graph showing the effect of retention time on the effectiveness of Cd removal using NaMBT (ie, removal of Cd from PLS). [Figure 6] FIG. 6 is a graph showing the effect of PLS ​​pH on the effectiveness of Cd precipitation with NaMBT, showing the concentrations of key metals remaining in solution at a NaMBT dose of about 400 mg / L and different pH values. [Figure 7] FIG. 7 is a graph showing the effect of PLS ​​pH on the effectiveness of Cd precipitation with NaMBT, showing copper (Cu) and Cd concentrations at a NaMBT dose of about 400 mg / L and different pH. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Recycling LiB waste through hydrometallurgical processes has many advantages but presents challenges, especially in the effective removal of impurities. One major obstacle is the complex composition of battery waste, which includes a diverse and numerous range of materials originating from electrodes, electrolytes, and separators. These components introduce a variety of contaminants, such as transition metals, organic solvents, and inorganic compounds, that may need to be separated and purified to ensure that the recovered materials meet quality standards for reuse.

[0012] Cross-contamination during the production of black mass from LiB waste is a key concern that further complicates the efficiency and sustainability of the recycling process. Due to the various chemicals and compositions of different battery types, there is a risk that undesirable elements and impurities will mix together, reducing the quality and value of the recovered materials. The inclusion of impurities as a result of mixing different types of LiB waste can impair the subsequent extraction process and pose challenges in achieving consistent product quality.

[0013] Cd, a toxic heavy metal, can be present in certain types of LiBs. Inclusion of Cd in black mass (inadvertently or otherwise) can lead to contamination of recovered materials. According to the present disclosure, the LiB recycling process can be simplified to facilitate the establishment of a sustainable LiB recycling ecosystem. Hence, the present disclosure describes an efficient process for the removal of Cd.

[0014] Referring now to the drawings, in which like reference numbers indicate like elements, an example of a process for recovering and purifying Ni, Mn, Co, and Li from black mass 100 is shown in Figure 1. In the illustrated example, the black mass 100 contains Cd as an impurity. If desired, the black mass 100 can be obtained from recycling LiB waste.

[0015] In the example illustrated in Figure 1, the black mass 100 is acid leached (S100) to form PLS containing valuable metals such as Ni, Mn, Co, and Li, impurities including Cd, and insoluble materials. In the illustrated example, the leaching process (S100) is a two-step process including (a) acid leaching (S102) with an acid (e.g., sulfuric acid (H2SO4)) under suitable conditions, and (b) reductive leaching (S104) with a reducing agent (e.g., hydrogen peroxide (H2O2)) under suitable conditions.

[0016] Next, in a separation step (S106), the acidic PLS 12 is separated from the insoluble material or acid leach residue 14. In a subsequent impurity removal step (S1080), the pH of the acidic PLS 12 is adjusted using a Li basic solution 16, and then Cd is removed from the PLS. The removal step (S1080) is described in more detail below in connection with FIG. 2.

[0017] The resulting pH adjusted slurry 18 is separated (S110) into an impurity precipitate 22 containing Cd and other impurities and a pH adjusted PLS 20 containing valuable metals such as Ni, Mn, Co, and Li.

[0018] 1 includes removing (S112) the remaining impurities from the pH-adjusted PLS 20 by adsorption using an ion exchange resin to form a purified PLS containing valuable metals such as Ni, Mn, Co, and Li. The removal step (S112) may include (a) eluting the adsorbed impurities from the ion exchange resin using a suitable eluent and (b) regenerating the ion exchange resin using a Li basic solution 16.

[0019] An adjustment step (S114) may then be performed to adjust the pH of the purified PLS containing valuable metals such as Ni, Mn, Co, and Li using Li basic solution 16 to form a mixed precipitate slurry. A separation step (S116) may be used to separate the mixed precipitate 24 containing Ni, Mn, and Co from the solution containing Li.

[0020] If desired, the mixed precipitate 24 can be of high purity (up to battery grade purity) for use as a precursor cathode active material. According to one aspect of the present disclosure, a battery manufacturer can adjust the concentration of any one or more of the valuable metals by adding corresponding battery grade metal sulfates prior to the conditioning step (S114), depending on the type of battery the manufacturer wishes to make.

[0021] Processing steps (S118, S120) may then be performed to produce Li basic solution 16. If desired, Li basic solution 16 may be an impure LiOH or Li2CO3 solution.

[0022] In the illustrated process, Li does not co-precipitate with Ni, Mn, and Co in step S114. Li can be recovered downstream of step S116 as Li2CO3 (by precipitation in step S118) or as LiOH.H2O (by crystallization downstream of step S120).

[0023] The feedstock to the process (i.e., black mass 100) can be a mixture of cathode and anode materials from recycling LiB waste or scrap, along with other materials. If desired, the LiB waste or scrap can include at least one of the LiB chemicals lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), and lithium titanate (LTO).

[0024] The black mass 100 may contain at least one of the valuable metals Ni, Co, Mn, and Li, impurities such as graphite (C), Cd, and at least one other impurity such as iron (Fe), aluminum (Al), Cu, phosphorus (P), calcium (Ca), magnesium (Mg), fluoride (F), zirconium (Zr), zinc (Zn), and rare earth elements (REE).

[0025] The method illustrated in Figure 1 includes a process for removing Cd as an impurity in step S1080, as described below in connection with Figure 2. If desired, the process of Figure 1 can be otherwise the same as that illustrated in Figure 1 of U.S. Patent Application No. 18 / 323,631, and can be operated under the same conditions to provide the same advantages as described in U.S. Patent Application No. 18 / 323,631.

[0026] Therefore, the present disclosure relates to a streamlined hydrometallurgical method for processing black mass 100 from LiB, which achieves efficient removal of Cd. As illustrated in Figure 1, the method begins with leaching (S100) the black mass 100 in acid to solubilize all metals of interest along with impurities such as Fe, Al, Cu, and Cd.

[0027] After removing the leaching residue 14, the acidic solution 12 proceeds to a series of impurity removal steps (S1080, S112). As illustrated in Figure 2, the first step (S200) of the series is impurity precipitation by pH adjustment. The first step (S200) is one of the impurity removal steps shown as "S1080" in Figure 1.

[0028] In the first step (S200 (FIG. 2)), most of the Fe, Al, and Cu are removed from the PLS12. The PLS then contains the critical metal Cd, as well as residual Al and Cu. In accordance with the present disclosure, Cd is removed prior to the precipitation of Ni, Mn, and Co under the conditions of the mixed precipitation or cathode precursor process (S114) (FIG. 1). Since Cd can be completely co-precipitated with Ni, Mn, and Co under the conditions of the mixed precipitation or cathode precursor process (S114), its prior removal (i.e., removal before step S114) is advantageous as a product impurity.

[0029] Thus, the second step (S202 (FIG. 2)) in the impurity removal process sequence is the removal of Cd from the PLS. The second step (S202) is one of the impurity removal steps (S1080) shown in FIG. 1. The second step (S202) is carried out by precipitating Cd as an insoluble organic complex by adding organic compound material 17 to the PLS.

[0030] The organic compound material may belong to a group including, but not limited to, organosulfur, organothiophosphate, and benzothiazole compounds or derivatives, or combinations thereof. The precipitate containing Cd and little or no critical metals may be removed by filtration and exit the process. The purified PLS20 then proceeds to the third step (S112) of impurity removal.

[0031] The third step (S112) in the impurity removal process sequence (S200, S202, S112) involves removal of residual Al and Cu impurities by ion exchange. After this third step (S112), the purified PLS proceeds to mixed precipitation (S114 (Figure 1)) for recovery of key metals as mixed metal hydroxides.

[0032] Test Data and Results Screening tests were conducted with several different organic-based reagents. An amount of reagent equivalent to approximately 400 mg / L in the resulting solution was added to the PLS, stirred at room temperature for at least 10 minutes, and then filtered. The filtrate was analyzed for metal content using inductively coupled plasma optical emission spectroscopy (ICP-OES), a known analytical technique for determining the amount of a particular element in a sample.

[0033] As shown in Table 1 (below), reagents containing dithiophosphinates, dithiophosphates, and / or mercaptobenzothiazole significantly reduced the concentration of Cd in solution with minimal precipitation of key metals. TIFF2025074009000001.tif193170

[0034] If Cd is not removed from the PLS containing a total of 90 g / L of Ni, Mn, and Co, the concentration of 30 mg / L will be converted to about 160 mg / kg in the mixed precipitation or cathode precursor product. Such a level is very high for a target of less than 5 ppm in the desired product. This means that to meet the desired specification for Cd, the PLS entering the mixed precipitation step (S114) should preferably contain a maximum Cd concentration of 0.3 mg / L.

[0035] Dose optimization studies were conducted using sodium 2-mercaptobenzothiazole (NaMBT) at different concentrations in PLS. Figures 3 and 4 are graphs of Cd precipitation using NaMBT at different doses showing (a) the profile of key metals in solution (Figure 3), and (b) the profile of Cd and P in solution (Figure 4). As shown in Figures 3 and 4, Cd was effectively removed at a dose of 400 mg / L with minimal precipitation of key metals. NaMBT is an aqueous solution of sodium 2-mercaptobenzothiazole.

[0036] To determine the effect of reaction time on the effectiveness of NaMBT in precipitating Cd from PLS, experiments were conducted comparing reaction times of 10 and 60 minutes. The same dose of NaMBT was used. As shown in Figure 5 (a graph showing the effect of retention time on the effectiveness of Cd removal using NaMBT), the 60 minute reaction time was found to be more effective than 10 minutes. These test results provide an opportunity to further reduce the effective dose of NaMBT.

[0037] To determine the effect of pH on the effectiveness of NaMBT in removing Cd from PLS, experiments were performed in which the same dose of NaMBT was added to solutions containing different levels of Cd at a retention time of 60 minutes. Figures 6 and 7 show that at the same dose of NaMBT, Cd was effectively removed from PLS with minimal or no co-precipitation of critical metals, even at pH 5. As also shown in Figure 7, NaMBT can precipitate significant amounts of Cu as well, providing an opportunity to eliminate what could otherwise be a subsequent Cu removal process step.

[0038] As used herein, the word "about" (or "approximately") modifies the associated value by plus or minus 10%. For example, in the present disclosure, "about" 100 units means not less than 90 units and not more than 110 units.

[0039] The present disclosure is not limited to the examples described herein. The claims which are desired to be protected by Letters Patent of the United States are as follows:

Claims

1. A method for recovering valuable metals from black mass, the black mass containing cadmium (Cd), the method comprising: removing said Cd from the pregnant leach solution (PLS); subsequently precipitating and recovering said valuable metals from the pregnant leach solution.

2. 2. The method of claim 1, wherein the valuable metals include one or more of nickel (Ni), manganese (Mn), cobalt (Co), and lithium (Li).

3. 2. The method of claim 1, wherein the removal of the Cd from the PLS comprises precipitating insoluble organic complexes by adding an organic compound material to the PLS.

4. The method of claim 3 , wherein the organic compound materials include organosulfur, organothiophosphate, and benzothiazole compounds or derivatives.

5. The method of claim 3 , wherein the organic compound material comprises a dithiophosphinate, a dithiophosphate, or a mercaptobenzothiazole.

6. 4. The method of claim 3, wherein the adding of the organic compound material comprises adding sodium 2-mercaptobenzothiazole (NaMBT) or an aqueous solution of NaMBT.

7. A method for recovering valuable metals from black mass, said black mass comprising Cd, said method comprising: removing the Cd from the PLS; and subsequently precipitating and recovering said valuable metals from the PLS, said valuable metals comprising one or more of Ni, Mn, Co, and Li.

8. 8. The method of claim 7, wherein the removal of the Cd comprises precipitating insoluble organic complexes by adding an organic compound material to the PLS.

9. A method for recovering valuable metals from black mass, said black mass comprising Cd, said method comprising: removing the Cd from the PLS, the removing of the Cd comprising precipitating insoluble organic complexes by adding an organic compound material to the PLS; and subsequently precipitating and recovering said valuable metals from the PLS.

10. 10. The method of claim 9, wherein the valuable metals include one or more of Ni, Mn, Co, and Li.

11. 10. The method of claim 9, wherein the organic compound materials include organosulfur, organothiophosphate, and benzothiazole compounds or derivatives.

12. The method of claim 9 , wherein the organic compound material comprises a dithiophosphinate, a dithiophosphate, or a mercaptobenzothiazole.

13. 10. The method of claim 9, wherein the adding of the organic compound material comprises adding sodium 2-mercaptobenzothiazole (NaMBT) or an aqueous solution of NaMBT.

14. The method of claim 9 , wherein the step of adding the organic compound material to the PLS causes precipitation of Cu.

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