Method for lithium battery recycling

Abstract

This disclosure provides methods for recycling material from lithium iron phosphate batteries. One aspect of this disclosure is a method for recycling lithium iron phosphate battery material. The method comprises a contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1: 1 to 1 :20, to form a black mass mixture; and b) leaching the black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer.

Description

METHOD FOR LITHIUM BATTERY RECYCLING

[0001] This disclosure relates to methods for recycling useful materials from used lithium batteries, especially lithium iron phosphate batteries.CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application Serial Number 63 / 568,495, filed March 22, 2024, the entire content of which is incorporated by reference herein.BACKGROUND

[0003] Lithium-ion batteries (LIBs) are being used in an increasing number of applications. Lithium iron phosphate (LiFePO4, abbreviated as LFP) batteries are preferred for certain applications because LFPs possess a high theoretical specific capacity (170 mAh / g), affordability, structural stability, safety, and environmentally friendly performance than other battery types. Among the various cathode materials, olivine-structured lithium iron phosphate has gained recognition as a promising cathode material for LIBs. Disposal of the high number of LFP batteries poses an environmental challenge due to potentially harmful chemical substances. Spent end-of-life LFP batteries have a high metal content that may exceed a level indicating profitability for recycling. Lithium in the batteries is recoverable for reuse.

[0004] Thus, there is an ongoing need to develop new processes for more efficient and more cost-effective methods for useful materials recycling of lithium iron phosphate batteries.BRIEF SUMMARY

[0005] This summary lists several embodiments of the presently disclosed subject matter, and in many cases lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. The mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this Summary does not list or suggest all possible combinations of such features.

[0006] This disclosure provides methods for recycling lithium batteries, especially material from lithium iron phosphate batteries.

[0007] One aspect of this disclosure is a method for recycling lithium iron phosphate battery material. The method comprises a contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1:1 to 1:20, to form a black mass mixture; and b) leaching the black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer. In the method, the black mass mixture and aqueous medium together form a black mass leaching mixture comprising solid residues in a lithium-containing solution. In another aspect, the method further includes measuring an oxidation-reduction potential of the lithium-containing solution and stopping the addition of the hydrogen peroxide when the oxidation-reduction potential is below 600 mV.

[0008] These and other steps will be discussed in detail below. Thus, the conduct of one or more additional steps beyond those described herein in performing a multi-step process of the invention falls within the scope of the claim coverage of this invention.

[0009] The above and other embodiments, objectives, features, and advantages of this invention will become still further apparent from the ensuing description, appended claims, and accompanying drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010] The presently disclosed subject matter can be better understood by referring to the following example figures. The components in the figure are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the presently disclosed subject matter (often schematically). In the figures, like reference numerals designate corresponding parts throughout the different views. A further understanding of the presently disclosed subject matter can be obtained by reference to an embodiment set forth in the illustrations of the accompanying drawing. Although the illustrated embodiment is merely for purposes of example of systems for carrying out the presently disclosed subject matter, both the organization and method of operation of the presently disclosed subject matter, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawings are not intended to limit the scope of this presently disclosed subject matter, which is set forth withparticularity in the claims as appended or as subsequently amended, but merely to clarify and provide examples of the presently disclosed subject matter.

[0011] FIG. 1 is a block flow diagram illustrating three method options to incorporate LFP BM into a spodumene conversion process in accordance with one embodiment.

[0012] FIG. 2 is a graph illustrating a comparison of lithium recovery after the leaching step after different process variations in accordance with one embodiment.

[0013] FIG. 3 is a graph illustrating a thermodynamic simulation of leach solutions as pH changes in accordance with one embodiment.DETAILED DESCRIPTION

[0014] Following the Definitions provided below, illustrative aspects of the subject matter claimed even further below will be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve one of ordinary skill in the art’s specific goals, such as compliance with application-related, system-related and / or business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0015] Definitions

[0016] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the presently disclosed subject matter.

[0017] While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0018] All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0019] Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and / or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and / or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus, the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and / or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and / or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

[0020] In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques.

[0021] Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims.

[0022] Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to "a cell" includes a plurality of such cells, and so forth.

[0023] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximationsthat can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0024] As used herein, the term “about,” when referring to a value or to an amount of a composition, dose, mass, weight, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions.

[0025] The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim.

[0026] As used herein, the phrase “consisting of’ excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0027] As used herein, the phrase “consisting essentially of’ limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.

[0028] With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0029] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

[0030] As used herein, the term “concentrated” when used in connection with a solution or in connection with a brine is meant to include a solution or brine that is saturated.

[0031] The disclosure may comprise, consist, or consist essentially of the materials and / or procedures recited herein.

[0032] As used herein, the term “about” modifying the quantity of an ingredient in the compositions of the disclosure or employed in the methods of the disclosure refers to variationin the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or use solutions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like. The term about also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term “about”, the claims include equivalents to the quantities.

[0033] As used throughout this document, the terms “room temperature” and “ambient temperature” are used herein to describe any temperature from 15° C to 35° C in which no external heat or cooling source is directly applied to the reaction vessel. Accordingly, the terms “room temperature” and “ambient temperature” encompass the individual temperatures and any and all ranges, subranges, and combinations of subranges of temperatures from 15°C to 35°C wherein no external heating or cooling source is directly applied to the reaction vessel.

[0034] As used throughout this document, the terms "atmospheric pressure" and "ambient pressure" are used herein to describe an earth air pressure wherein no external pressure modifying means is utilized. Generally, unless practiced at extreme earth altitudes, "atmospheric pressure" is about 1 atmosphere (alternatively, about 14.7 psi or about 101 kPa).

[0035] Throughout this document, the abbreviation LFP refers to lithium iron phosphate batteries, and the abbreviation CAM refers to cathode active material. Battery black mass is abbreviated as BM.

[0036] General Procedure

[0037] One conventional solution for treating spent LFP batteries involves the extraction of precious metals from used materials through hydro metallurgy, employing mineral acids such as H2SO4, HC1, or organic acids as leaching agents. Given the stability of LFP and its olivine structure, the volume of acid required significantly surpasses the stoichiometric consumption, resulting in substantial wastewater production and increased recycling costs.

[0038] An improved method provides selective leaching of Li from spent LFP, which enables the concurrent enrichment of an Li-rich solution and FePO4 precipitate. However, the reagents involved in selective leaching, such as organic acids and H2O2, are relatively costly. Furthermore, users may desire higher Li recovery rate than is achieved in existing selective leaching methods. The methods of this disclosure provide an improved, cost- effective process for recycling LFP from the spent batteries.

[0039] FIG. 1 is a block flow diagram illustrating three method options to incorporate LFM BM into a spodumene conversion process in accordance with one embodiment. The block flow diagram illustrates a LFP BM Production Process 101 and a Spodumene Conversion Process 102. Three options to combine portions of these two processes are illustrated.

[0040] The methods described are typically applied to disused or end-of-life lithium batteries, normally after discharging and dismantling the batteries. Battery black mass is typically formed from at least lithium-ion disused or end-of-life batteries. Battery black mass (BM) comprises one or more metal-containing compounds, generally selected from the group consisting of lithium and iron, although one or more other metals, such as manganese, cobalt, nickel, copper, zinc, and / or aluminum, may be present as well.

[0041] As illustrated in FIG. 1, in the LFP BM Production Process 101, a first block includes battery dismantling and discharging 104. As part of the dismantling process, the process often includes a pretreatment to remove the electrolyte solution, typically by evaporation. Then the battery is subjected to a process comprising shredding, crushing, and / or sieving, preferably shredding, crushing, and sieving, along with separations of metal casings and plastic components, to form a battery black mass.

[0042] In block 104, the method evaporates electrolytes and separates metals from the black mass. In some embodiments of this disclosure, the battery black mass is pre-treated to remove copper (Cu), unless the battery black mass is known to be devoid of copper, so that copper is not present in any material amount in the methods according to the disclosure.

[0043] Sulfates present in the process can include sulfates from sulfuric acid, an alkali metal hydrogen sulfate (such as, e.g., sodium hydrogen sulfate or potassium hydrogen sulfate), an alkali metal sulfate (such as, e.g., sodium sulfate or potassium sulfate), or a mixture of any two or more of these.

[0044] The battery black mass is generally in the form of a powder 108, preferably a granular powder. The battery black mass powder 108 is preferably a granular powder, and preferably has an average particle size of about 500 microns or less, more preferably about 300 microns or less. The battery black mass can be subjected to particle size reduction techniques such as grinding or milling to achieve the desired particle sizes.

[0045] The black mass powder 108 may be treated to separate a graphite product 110. Often, battery black mass contains graphite from the lithium battery. In some preferred embodiments of this disclosure, the battery black mass is subjected to an optional process to remove the graphite. The process for removal of graphite from the battery black mass isfrequently a flotation process. The flotation process can have more than one stage. Typical flotation procedures for graphite removal from battery black mass include froth flotation. In froth flotation, the foaming agent can be 4-methyl-2-pentanol (methyl isobutyl carbinol), and the graphite collector can be kerosene. The product of the flotation procedure is a “clean” battery black mass preferably containing little or no graphite. After removal of graphite, battery black mass is considered to be a cathode active material (CAM) such as clean LFP CAM 112.

[0046] The Spodumene Conversion Process 102 illustrates the process to convert the crystal structure of spodumene from the natural monoclinic a-form to the tetragonal P-form.

[0047] A spodumene concentrate 114 is provided. Spodumene is a lithium aluminum silicate ore. The spodumene concentrate 114 may be in the form of a powder or a slurry. Generally, a solvent is a polar protic solvent; water is a preferred polar protic solvent. Preferably, the spodumene concentrate 114 comprises sulfate ions; the source of the sulfate ions in the spodumene composition is typically sulfuric acid, an alkali metal hydrogen sulfate (such as sodium hydrogen sulfate or potassium hydrogen sulfate), an alkali metal sulfate (such as sodium sulfate or potassium sulfate), or a mixture of any two or more of these. More preferably, the spodumene concentrate 114 is a powder comprising sulfate ions or an aqueous slurry comprising sulfate ions. The concentration of spodumene in the spodumene concentrate 114 is generally about 0.2 mol / L or more, preferably about 0.45 mol / L or more.

[0048] The spodumene concentrate 114 is treated in a calcination 116 process. The calcination 116 may be at 1000 degrees C or higher to transform the natural monoclinic a- form to the tetragonal P-form. The process of calcination makes spodumene more brittle and reactive for subsequent acid roasting.

[0049] Next, the transformed spodumene is milled in a milling process 118. The spodumene may be milled or ground in any suitable grinding or milling process 118. In an example, the spodumene is milled in a ball mill or a hammer mill.

[0050] The ground spodumene is treated in an acid roasting 120 process. In an example, the spodumene is acid roasted at 250 degrees C using sulfuric acid. During acid roasting, the spodumene is converted to an acidified spodumene ore (ASO). Finally, the ASO is treated in a Li digestion 122 process. The Li digestion 122 occurs through water leaching and pH adjustment. The product of the Li digestion 122 is further processed in a Li purification and conversion 124 process.

[0051] The method of this disclosure comprises three options to introduce the LFP BM to the Spodumene Conversion Process 102. The three options represent three different points in the Spodumene Conversion Process 102 at which to combine the LFP BM with the spodumene being processed. The three options are illustrated as Option 1, Option 2, and Option 3.

[0052] In Option 1, the black mass powder 108 is introduced to the spodumene at the calcination 116 stage. The black mass powder 108 is used before the flotation or other process that removes the graphite product 110. Therefore, the graphite product 110 is still in the black mass powder 108 when the black mass powder 108 is combined with the spodumene.

[0053] The calcination 116 process will burn off the graphite, organic solvents, and any binders such as polyvinylidene fluoride (PVDF) which is commonly found in lithium-ion batteries. The calcination 116 process will decompose complex electrolytes. In the process of Option 1, attention must be paid to the handling of additional combustion byproducts. For example, PVDF or any other perfluoroalkylated substances (PFAS) materials may emit hydrofluoric acid. These materials may accumulate in the calciner’s scrubber. The organic material and graphite would likely burn off into carbon dioxide gas in an oxidizing atmosphere. Further efforts may be required to ensure that explosive levels are not attained. Another risk that may be encountered in Option 1 is if the calciner contains a nonoxidizing atmosphere, the excess graphite could encourage carbothermic reductions to occur. Unfavorable byproducts could result from this, such as oxygenated anions (PO43-, SO42) being reduced into their elemental forms (P4, Ss).

[0054] In Option 2, clean LFP CAM 112 is added to the spodumene during or before the acid roasting 120 process. To obtain the LFP CAM 112, flotation or other processing steps are performed on the black mass powder 108 to remove the graphite product 110. After graphite removal, the LFP CAM 112 is introduced to the spodumene during or before the acid roasting 120. Option 2 uses the LFP CAM 112 instead of the black mass powder 108 because the graphite in the black mass powder 108 would consume sulfuric acid at the temperature of the acid roasting 120 process. The consumption of sulfuric acid, which is an oxidizing agent, would yield carbon dioxide and sulfur dioxide. These compounds would require a scrubber for removal.

[0055] PFAS compounds, such as bis-perfluoroalkyl sulfonimides (bis-FASIs) and PVDF, can undergo thermal decomposition and chemical degradation. The high temperature and acidic conditions of the acid roasting 120 process may break down these compounds into smaller, potentially toxic byproducts. The degradation process may release variousfluorinated byproducts, which may include perfluoroalkyl acids (PFAAs) and other persistent organic pollutants. The release of these byproducts may pose environmental and health risks.

[0056] In Option 3, the clean LFP CAM 112 is introduced to the spodumene at the Li digestion 122 process. By using LFP CAM 112 instead of the black mass powder 108, Option 3 can effectively prevent the introduction of graphite into the spodumene tailings. Option 3 poses a decreased processing risk compared to Options 1 and 2. The acidified P-spodumene ore (ASO) is introduced into a pH neutralization tank before further processing. This approach adds value to LFP CAM 112 beyond just the lithium content, as its alkalinity reduces the need for additional CaCOs for neutralization. Additionally, this method is advantageous from an atom economy perspective, as the excess sulfuric acid from acid roasting is utilized more effectively, performing useful work rather than being neutralized.

[0057] In the event that some amount of graphite is not successfully removed through flotation, at least a portion of the remaining graphite will be subsequently eliminated after the Li digestion process. This elimination will occur during the pH neutralization step, in which a filtration step is incorporated before the addition of Ca(OH)2 and CaCCh. This additional filtration step ensures the complete removal of graphite and other solids, thereby maintaining the purity of the final product. Another consideration is the presence of PFAS. Should PFAS regulations pose a compliance issue, the process may remove PFAS from the LFP BM before it is introduced into the Spodumene Conversion Process 102. This preemptive removal ensures that the process adheres to all regulatory requirements and maintains the highest standards of environmental safety.

[0058] In an example of Option 3, the system contacts a LFP BM, such as LFP CAM, from a lithium iron phosphate battery material and a spodumene composition at the Li digestion 122 process in a weight ratio of spodumene composition to LFP BM of about 1:1 or more, to form a black mass mixture. Preferably, the weight ratio of spodumene composition to battery black mass is about 2:1 or more, more preferably about 5:1 or more, even more preferably about 7.5:1 or more. In other examples, the weight ratio of spodumene composition to LFP BM is 10:1 or more, 15:1 ormore, or 20:1. For the weight ratio of the spodumene composition to battery black mass, the spodumene composition weight does not include the weight of any solvent that is present in the spodumene composition.

[0059] The contacting of the LFP BM and the spodumene composition can occur at room temperature or at elevated temperatures, or the contacting can be initiated at room temperature and then the temperature can be raised to any desired elevated temperature(s). Elevatedtemperatures often include temperatures in the range of about 30°C to about 300°C, preferably about 30°C to about 60°C.

[0060] In the method of this disclosure, the LFP BM is leached with an aqueous medium in a weight ratio of aqueous medium to black mass mixture of about 5:1 or more, preferably about 10:1 or more, to form a leached mixture containing solid residues. The aqueous medium is either water or an aqueous acidic medium, in which the acid is usually an inorganic acid, typically selected from hydrochloric acid, nitric acid, and sulfuric acid, preferably sulfuric acid. The black mass mixture and aqueous medium together form a black mass leaching mixture.

[0061] The black mass leaching mixture has a pH in the range of about 2.5 to about 3.0, generally provided and / or maintained by adding an acid, usually an inorganic acid, typically selected from hydrochloric acid, nitric acid, and sulfuric acid, preferably sulfuric acid. In a preferred embodiment, the pH is 2.7 to 2.9 or about 2.8. The leaching is normally performed with agitation, preferably at speeds of about 100 rpm or more, preferably about 200 rpm or more, more preferably about 300 rpm or more.

[0062] The leaching of the black mass leaching mixture can occur at room temperature or at elevated temperatures, or the contacting can be initiated at room temperature and then the temperature can be raised to any desired elevated temperature(s). Elevated temperatures often include temperatures in the range of about 30°C to about 100°C, preferably about 30°C to about 60°C.

[0063] In some preferred embodiments of the leaching of the black mass mixture with an aqueous medium, an oxidant such as oxygen, ozone, or hydrogen peroxide, is added to the combination of the black mass mixture and the aqueous medium. One preferred oxidant includes hydrogen peroxide. The oxidant is preferably used in about stoichiometric amounts or less relative to the Fe2+from the LFP (LiFePO4). In an example, amounts of oxidant greater than stoichiometric can be used. When hydrogen peroxide and / or sulfuric acid are used as oxidants, organic matter that is present will be oxidized and produce carbon dioxide gas. Option 3 accounts for this effect by subjecting the LFP BM to a graphite removal process before combining the clean LFP CAM 112 with the spodumene composition.

[0064] In some embodiments of this disclosure, the contacting step and the leaching step are carried out in the same temperature range, and the temperatures are typically about 25 °C to about 60°C, preferably about 25°C to about 55°C, more preferably about 35°C to about 50°C.

[0065] The method of this disclosure also comprises separating the solid residues from the leached mixture containing solid residues to form an initial lithium-containing solution. Separation can be carried out by methods known in the art, such as decantation, centrifugation, or filtration; filtration is often preferred.

[0066] The pH of the initial lithium-containing solution being controlled to be about 2.8 causes precipitates and a clarified lithium-containing solution to form. In some embodiments, the adjusting of the pH is carried out by combining a base with the initial lithium-containing solution; preferably, at least a portion of the base is in the form of an aqueous solution. The base is preferably calcium hydroxide, calcium carbonate, sodium hydroxide, or any combination of two or more of the foregoing. In some embodiments, the adjusting of the pH is carried out by combining an acid with the initial lithium-containing solution; preferably, at least a portion of the acid is sulfuric acid.

[0067] The identity of the precipitates formed depends on what species are soluble or insoluble at the pH value of the solution. By adjusting the pH, specific compounds or species can be induced to precipitate from the solution. Precipitates formed in this step often comprise one or more of FePCH, Al(0H)3, CaSCh, AkSiCh, and xAHCh^ySiCh^zH’O. In one aspect of the disclosure, pH is adjusted into the range of about 2.5 to about 3.5, about 2.0 to about 3.0, or about 2.0 to about 3.5. Various acids and bases may be employed to adjust the pH. In some aspects, sodium hydroxide or sulfuric acid, for example, may be employed to adjust the pH, in order to avoid introducing various other compounds or species into the system. A buffer such as glycine-HCl can be added to the solution containing acidified spodumene ore and the LFP BM to hold the pH between 2.2 to 3.6. Particularly at larger scales, such as at an industrial level, the buffer facilitates easier pH control.

[0068] In a further step, the method of this disclosure can comprise separating the precipitates from the clarified lithium-containing solution to form a lithium sulfate solution. Separation can be carried out by methods known in the art, such as decantation, centrifugation, or filtration; filtration is often preferred. When sulfate ions are not present in the clarified lithium-containing solution, a sulfate-containing reagent is introduced to the clarified lithium-containing solution. Sulfate-containing reagents include sulfuric acid, an alkali metal hydrogen sulfate (such as sodium hydrogen sulfate or potassium hydrogen sulfate), an alkali metal sulfate (such as sodium sulfate or potassium sulfate), or a mixture of any two or more of these; preferably, the sulfate-containing reagent comprises sulfuric acid.

[0069] The following examples are presented for purposes of illustration and are not intended to impose limitations on the scope of this disclosure. In the examples, the conventional hydrometallurgy process was examined as a reference and compared to the technologies described herein. The conventional acid leaching method utilizes inorganic acids to extract lithium and remove graphite in a single step. This is followed by a pH adjustment to 7 to precipitate FePCH- While this technique can achieve high lithium recovery rates, the conventional process necessitates a substantial initial investment, resulting in high capital expenditures that is not required with the methods described herein.EXAMPLE 1

[0070] The experimental setup used included a 4 neck round bottom reactor, pH probe, oxidation-reduction potential (ORP) probe, thermometer probe, heating mantle, and stir plate. The pH probe, thermometer probe, and ORP probe were inserted into a neck of the 4-neck flask; the remaining neck of the flask was used for reagent introduction and sampling.

[0071] A study was performed to compare how adding battery black mass from a lithium iron phosphate battery to spodumene powder containing sulfuric acid changed the amount of Li obtained over 5 days from the leaching of the black mass mixture in an aqueous medium, where the aqueous medium was water. Three runs were performed; in one run, no spodumene composition was used, and in another run, no battery black mass was present. The runs in which no spodumene composition was present and in which no battery black mass was present are comparative runs. In the remaining run, both an aqueous slurry of spodumene containing sulfuric acid and battery black mass from a lithium iron phosphate battery. The ratio of LFP BM to ASO was 1:5. A volume of water was added to the mixture to create a liquid to solid ratio of 10:1. The resulting was stirred continuously at a speed exceeding 300 RPM throughout the process to ensure thorough mixing.

[0072] The pH and oxidation-reduction potential (ORP) were recorded at the onset of the experiment and subsequently at specific intervals, ranging from every 15 to 60 minutes, depending on the duration of the experiment. Daily samples were collected and filtered using a 0.25 (im filter syringe tip, with duplicate samples of 2 ml each.

[0073] FIG. 2 is a graph illustrating a comparison of lithium recovery after the leaching step after different process variations in accordance with one embodiment. As shown graphically in Figure 1 , lithium recovery from battery black mass in the absence of a spodumene composition is minimal (diamonds), lithium recovery from an aqueous slurry of spodumenecontaining sulfuric acid in the absence of battery black mass is measurable (squares), and lithium recovery from a combination of 1:5 ratio of ASO to LFP BM containing sulfuric acid (triangles) is higher than the combined amount recovered from battery black mass alone and a spodumene composition alone. These results are summarized below in Table 1.TABLE 1

[0074] * Comparative run.EXAMPLE 2

[0075] The experimental setup used included a 4 neck round bottom reactor, pH probe, oxidation reduction potential (ORP) probe, thermometer probe, heating mantle, and stir plate. Each probe was inserted into a neck of the 4-neck flask; the neck for the thermometer probe was be used alternatively for reagent introduction and sampling.

[0076] In this experiment, H2O2 is used as an oxidizer to determine the effect on a speed of the reaction. In each experimental run, an LFP BM and a spodumene composition, which was a powder formed from a roasted mixture of spodumene and sulfuric acid, were added to the flask in order to place sulfate into the black mass mixture. The contacting of the LFP BM and the spodumene composition formed a black mass mixture. Water was added to the flask to achieve or maintain the desired liquid to solid ratio, and the pH was maintained at 2.00 to 2.30 by adding concentrated 93-98% H2SO4 (aq.) as needed during the leaching of the black mass (leaching) mixture. The pH and oxidation-reduction potential (ORP) of the solution were monitored, and recorded at the beginning of the contacting and at various intervals (every 15to 60 minutes). Samples (duplicate samples of 2 mL) were taken and filtered using a 0.25- pm filter syringe tip before analysis.

[0077] HzC was added dropwise while monitoring the ORP and the pH. Whenever necessary, H2SO4 was added dropwise to maintain the pH within the desired range (2.00 to 2.30). H2O2 was added until the desired ORP (<600 mV vs. Ag / AgCl) was reached. The temperature of the black mass leaching mixture was increased to 45 °C, and the temperature was maintained at 45 °C with stirring at a constant speed of 500 rpm for 1 hour. After 1 hour, the solution of black mass leaching mixture was filtered using a vacuum filtration system.

[0078] Leachate from the black mass leaching mixture solution was separated from the solid residue present therein, which solid residue was collected from 3 consecutive washes using a liquid to solid ratio of 2: 1 for each wash (for example, if the total solid added to the system at the beginning of the experiment was 30 g, we added 60 g water for each wash). During the washes, 30 to 45 g of water was added initially to dissolve a major part of the filtered solid residue, which solid residue was filtered using a Buchner filter funnel. The remaining 15 to 30 g of water (from total of 60 g used for the wash) was then added to dissolve the remaining solid residue. Leachate from each wash was collected in a separate bottle and analyzed using Li NMR and ICP-MS, and the Li content results from each bottle were added up to obtain the amount of Li recovered from the initial leachate.

[0079] The experimental conditions are summarized in Table 2.TABLE 2

[0080] The addition of the H2O2 as an oxidizing agent decreased the recovery time from 4- 5 days to 1-2 hours. The Li recovery was higher (83-95% vs. 73%).EXAMPLE 3 - DETERMINING THE PH WINDOW

[0081] In experiments, OLI simulation software was used to identify the optimal pH range for recovering Lithium (Li) while simultaneously precipitating iron phosphate (FePO4). The simulation software allowed for conducting experiments across every pH range to determine the best conditions for optimal lithium recovery from the ASO / LFP BM mixture.

[0082] FIG. 3 is a graph illustrating a thermodynamic simulation of leach solutions as pH changes in accordance with one embodiment. FIG. 3 illustrates the concentration of various ions contributing to the reactions during the leaching process across a pH range of 0 to 7. At a pH of approximately 2.8, both iron (Fe3+) and phosphorus (P5+) exhibit the lowest solubility. In contrast, lithium (Li+) remains soluble in the solution. This difference in solubility enables the separation of the lithium stream, in the form of LiSO4, from the precipitated FePO4.

[0083] Table 2 illustrates example elemental compositions of LFP CAM, LFP BM, and acidified spodumene ore. The LFP CAM contains the highest amount of Li at 4.7%, compared to 2.25% in the LFP BM and 2.1% in the acidified spodumene ore (ASO). In this study, the LFP CAM represents the clean LFP BM after the flotation process that removes graphite content from the LFP BM. The LFP CAM contains only 1.5% carbon, in contrast to the LFP BM, which has a carbon content exceeding 45%.TABLE 3TABLE 3 continued

[0084] Table 4 presents a detailed comparison between the co-feed with spodumene method as described herein and a conventional hydrometallurgical (acid leaching) method, focusing on Li recovery and FePCL removal efficiencies.

[0085] For the LFP CAM, the co-feed with spodumene method of Option 3 achieves a Li recovery rate of approximately 91%. In contrast, the acid leaching method achieves nearly 100% lithium recovery. Despite the slight difference in lithium recovery rates, the efficiency of FePO4 removal is found to be comparable for both methods, with each exceeding 98%.

[0086] When examining the LFP BM, the co-feed with spodumene as in Option 1 results in a Li recovery rate of approximately 83%, which is significantly higher than the approximately 44% achieved through the acid leaching process.TABLE 4

[0087] The lower-than-expected lithium recovery rate for the acid leaching process in the case of LFP BM may be attributed to multiple factors. For example, each LFP BM, depending on its composition, will have slightly different pH requirements for optimal lithium recovery. Based on the experiments conducted, the composition of LFP BM necessitates slightly elevated pH levels for optimal lithium recovery. A set of experiments was conducted to study how pH elevation can affect lithium recovery for the LFP BM, as shown in Table 5. Additionally, the efficiency of FePCL removal slightly improves with increasing pH.

[0088] Based on the experiments, an increase in pH, from 1.66 + 0.25 to 2.76 + 0.18 corresponds to an improvement in lithium recovery, from approximately 30% to 50%. This result indicates that a higher pH in the range of 2.5 to 3.0 is required for the optimal recovery of lithium from the LFP BM.TABLE 5TABLE 5 ContinuedEXAMPLE 4 - CHEMIAL CONSUMPTION COMPARISON

[0089] As illustrated in Table 6, when a comparison is drawn between the co-feed process with spodumene described herein and the conventional hydrometallurgical process, the results indicate that the co-feed process significantly reduces the need for various chemicals and reagents. For example, for LFP CAM the co-feed process used only 15% of the sulfuric acid (H2SO4) and 18% of the hydrogen peroxide (H2O2) required by the acid leaching method. Similarly, for the LFP BM, the co-feed process used only 2% of the sulfuric acid (H2SO4) and 16% of the hydrogen peroxide (H2O2) required by the acid leaching method. For the LFP BM, adjusting the pH to higher values required the use of sodium hydroxide in both the co-feed and acid leaching processes. However, a notable trend was observed: the co-feed process with spodumene used only 20% of the sodium hydroxide compared to the acid leaching process. This result further illustrates the efficiency and environmental benefits of the cofeeding method described herein, making the method a more sustainable and cost-effective choice.

[0090] These calculations do not take into account the amount of sulfuric acid used during the acid roasting process to acidify the -spodumene.TABLE 6EXAMPLE 5 - LFP CAM LI STREAM QUALITY

[0091] When evaluating the quality of the lithium stream, the use of LFP CAM as in Option 3 provides a result with reduced impurities in the final lithium stream. This result is illustrated in Table 7. In the examples illustrated in Table 7, the pre-processing described in Option 3 is recommended to achieve optimal results. In contrast, the LFP BM process described in Option 1 shows lower Li recovery.

[0092] Additionally, LFP BM contains higher levels of impurities, including fluorine, which is likely derived from the binder and electrolyte used in the process. The sodium present in the lithium stream primarily originates from the addition of sodium hydroxide (NaOH) to adjust the pH levels.TABLE 7TABLE 7 Continued

[0093] One aspect of this disclosure is a method for recycling lithium iron phosphate battery material. The method comprises a contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1: 1 to 1:20, to form a black mass mixture; and leaching the black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer. In the method, the black mass mixture and aqueous medium together form a black mass leaching mixture comprising solid residues in a lithium-containing solution.

[0094] In another aspect, the method further includes measuring an oxidation-reduction potential of the lithium-containing solution and stopping the addition of the hydrogen peroxide when the oxidation-reduction potential is below 600 mV. In another aspect, the method includes separating the solid residues from the leached mixture containing solid residues to form an initial lithium-containing solution. In another aspect, the spodumene composition, before contacting the lithium iron phosphate battery material in step a), is acid roasted with sulfuric acid.

[0095] In another aspect, the method includes shredding, crushing, and / or sieving the lithium iron phosphate battery material to form the battery black mass prior to contacting the battery black mass and the spodumene composition, optionally wherein the battery black mass formed is a granular powder that is 500 microns or less. In another aspect, removing graphite from the battery black mass prior to contacting the battery black mass and the spodumene composition. In another aspect, the graphite is removed by using a flotation process, such as a froth flotation process.

[0096] In another aspect, the weight ratio of the battery black mass to the spodumene composition in a) is about 1:5, and the weight ratio of the black mass mixture to the aqueous medium is about 1:5 or more. In another aspect, the aqueous medium to form the leached mixture in b) is either water or an aqueous acidic solution.

[0097] In another aspect, during the leaching step, the black mass leaching mixture is agitated at a speed of about 300 rpm or more. In another aspect, the separating of the solid residues from the mixture containing solid residues is carried out by filtration. In another aspect, the adjusting of the pH is carried out by combining a base with the initial lithium- containing solution, optionally wherein at least a portion of the base is in the form of an aqueous solution.

[0098] In another aspect, the base is calcium hydroxide, calcium carbonate, sodium hydroxide, or any combination of two or more of the foregoing. In another aspect, the adjusting of the pH is carried out by combining an acid with the initial lithium-containing solution, optionally wherein at least a portion of the acid is sulfuric acid.

[0099] In another aspect, the method includes separating the precipitates from the clarified lithium-containing solution to form a lithium sulfate solution; when sulfate ions are not present in the clarified lithium-containing solution, a sulfate-containing reagent is introduced to the clarified lithium-containing solution. In another aspect, a sulfate-containing reagent is introduced, optionally wherein the sulfate-containing reagent comprises sulfuric acid.

[0100] In another aspect, a method for recycling lithium iron phosphate battery material is characterized by contacting a battery black mass from the lithium iron phosphate battery material and a spodumene composition in a weight ratio of spodumene composition to battery black mass of about 1:1 or more, to form a black mass mixture, and leaching the black mass mixture with an aqueous medium in the presence of hydrogen peroxide, to form a leached mixture comprising solid residues in a lithium-containing solution.

[0101] In another aspect, the weight ratio of the black mass mixture to the aqueous medium is about 1:5 or more. In another aspect, the amount of sulfates present is at least stoichiometric relative to lithium content of the black mass mixture. In another aspect, the black mass leaching mixture has a pH in the range of about 2.5 to about 3.0.

[0102] This disclosure is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the disclosure to the particular exemplifications presented hereinabove.

[0103] While the present invention has been described in terms of one or more preferred embodiments, it is to be understood that other modifications may be made without departing from the scope of the invention, which is set forth in the claims below.

Claims

CLAIMSThat which is claimed is:

1. A method for recycling lithium iron phosphate battery material, the method comprising: a) contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1:1 to 1:20, to form a black mass mixture; and b) leaching the black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture to between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer, wherein the black mass mixture and aqueous medium together form a black mass leaching mixture comprising solid residues in a lithium-containing solution.

2. The method of claim 1, further comprising measuring an oxidation-reduction potential of the lithium-containing solution.

3. The method of claim 2, stopping the addition of the hydrogen peroxide when the oxidationreduction potential is below 600 mV.

4. The method of claim 1, further comprising separating the solid residues from the leached mixture containing solid residues to form an initial lithium-containing solution.

5. The method of claim 1, wherein the spodumene composition, before contacting the lithium iron phosphate battery material in step a), is acid roasted with sulfuric acid.

6. The method of claim 1, further comprising shredding, crushing, and / or sieving the lithium iron phosphate battery material to form the battery black mass prior to contacting the battery black mass and the spodumene composition, optionally wherein the battery black mass formed is a granular powder.

7. The method of claim 1, wherein the battery black mass formed is a granular powder optionally having an average particle size of about 500 microns or less at the time of contacting in step a).

8. The method of claim 1, comprising removing graphite from the battery black mass prior to contacting the battery black mass and the spodumene composition in step a).

9. The method of claim 8, wherein the removing of graphite from the battery black mass is carried out using a flotation process.

10. The method of claim 9, wherein the flotation process is a froth flotation process, optionally wherein i) 4-methyl-2-pentanol (methyl isobutyl carbinol) is a foaming agent and / or ii) kerosene is a graphite collector.

11. The method of claim 1, wherein the weight ratio of the battery black mass to the spodumene composition in a) is about 1:5.

12. The method of claim 1, wherein the weight ratio of the black mass mixture to the aqueous medium is about 1:5 or more.

13. The method of claim 1, wherein the aqueous medium to form the leached mixture in b) is either water or an aqueous acidic solution.

14. The method of claim 1, wherein during the leaching step b), the black mass leaching mixture is agitated at a speed of about 300 rpm or more.

15. The method of claim 4 wherein the separating of the solid residues from the mixture containing solid residues is carried out by filtration.

16. The method of claim 1, wherein the adjusting of the pH is carried out by combining a base with the initial lithium-containing solution, optionally wherein at least a portion of the base is in the form of an aqueous solution.

17. The method of claim 16, wherein the base is calcium hydroxide, calcium carbonate, sodium hydroxide, or any combination of two or more of the foregoing.

18. The method of claim 4, wherein the adjusting of the pH is carried out by combining an acid with the initial lithium-containing solution, optionally wherein at least a portion of the acid is sulfuric acid.

19. The method of claim 4, comprising separating the precipitates from the clarified lithium- containing solution to form a lithium sulfate solution; when sulfate ions are not present in the clarified lithium-containing solution, a sulfate-containing reagent is introduced to the clarified lithium-containing solution.

20. The method of claim 19, wherein a sulfate-containing reagent is introduced, optionally wherein the sulfate-containing reagent comprises sulfuric acid.

21. A method for recycling lithium iron phosphate battery material, characterized by contacting a battery black mass from the lithium iron phosphate battery material and a spodumene composition in a weight ratio of spodumene composition to battery black mass of about 1: 1 or more, to form a black mass mixture, and leaching the black mass mixture with an aqueous medium in the presence of hydrogen peroxide, to form a leached mixture comprising solid residues in a lithium-containing solution.

22. The method of claim 21, wherein the weight ratio of the black mass mixture to the aqueous medium is about 1:5 or more.

23. The method of claim 21, wherein an amount of sulfates present during the leaching is at least stoichiometric relative to lithium content of the black mass mixture.

24. The method of claim 21, wherein the black mass mixture has a pH in the range of about 2.5 to about 3.0.

25. The method of claim 21, wherein the spodumene composition, before contacting the lithium iron phosphate battery material, is acid roasted with sulfuric acid.

26. A method for recycling lithium iron phosphate battery material, the method comprising: a) contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1: 1 or more, to form a black mass mixture; and b) treating the black mass mixture in a calcination process; c) acid roasting the treated black mass mixture; d) leaching the treated black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture to between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer, wherein the treated black mass mixture and aqueous medium together form a treated black mass leaching mixture comprising solid residues in a lithium-containing solution.

27. The method of claim 26, wherein graphite in the battery black mass is burned off in the calcination process.

28. A method for recycling lithium iron phosphate battery material, the method comprising: a) contacting a battery black mass from a lithium iron phosphate battery material and a spodumene composition in a weight ratio of battery black mass to spodumene composition of about 1:1 or more, to form a black mass mixture; and b) acid roasting the treated black mass mixture; c) leaching the treated black mass mixture with an aqueous medium by: adjusting a pH of the black mass mixture to between 2.5 and 3.0; and adding hydrogen peroxide as an oxidizer, wherein the treated black mass mixture and aqueous medium together form a treated black mass leaching mixture comprising solid residues in a lithium-containing solution.

29. The method of claim 28, comprising removing graphite from the battery black mass prior to contacting the battery black mass and the spodumene composition in step a).

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