Method for lithium recovery from LFP black mass with enhanced impurity removal

Abstract

The present disclosure teaches a multi-stage process for treating phosphate-containing lithium-ion battery black mass, including LFP-derived black mass, to recover lithium and remove fluoride and metal impurities. The process comprises non-oxidizing acid leaching to maintain iron predominantly in the ferrous state, followed by staged impurity removal through controlled pH adjustment to selectively remove aluminum, copper, and fluoride species in a first impurity removal stage while maintaining iron in solution, and subsequent removal of alkaline earth metals and residual iron species in a second impurity removal stage. The process enables recovery of lithium as a high-purity lithium compound suitable for battery manufacturing.

Description

Method for Lithium Recovery from LFP Black Mass with Enhanced Impurity RemovalTECHNICAL FIELD

[0001] The present disclosure relates generally to lithium (Li) recovery, and in particular to a process for the recovery and purification of Li from lithium iron phosphate (LFP) battery waste with enhanced impurity removal.BACKGROUND

[0002] The global demand for lithium-ion batteries (LiBs) has skyrocketed due to their widespread use in electric vehicles (EVs), portable electronics, and renewable energy storage systems. LiBs are considered the most commercially viable energy storage solution due to their high energy density, long cycle life, and efficiency. However, as the use of LiBs continues to increase, so does the accumulation of battery waste, including manufacturing scrap and spent or end-of-life (EOL) batteries, that need to be recycled or safely disposed. Improper disposal of these batteries presents serious environmental hazards, as they contain a range of toxic and hazardous materials, which may include heavy metals such as cobalt (Co), nickel (Ni), and manganese (Mn) depending on battery chemistry, as well as lithium salts, electrolytes, and fluorinated compounds, which can lead to soil and water contamination.

[0003] The recycling of LiBs is of critical importance, not only for environmental reasons but also to recover critical metals. The mining of these materials is often concentrated in a few regions, and the extraction processes can be environmentally destructive and expensive. Given the geopolitical risks associated with the supply of these metals and their finite nature, recycling these metals from LiB waste offers a viable solution to mitigate supply chain risks and reduce reliance on primary mining operations.

[0004] Among the various chemistries available for LiBs, Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP) have emerged as two of the most prevalent and widely adopted options in current and emerging markets. These chemistries are expected to play a dominant role in the next generation of battery technologies, driven by their unique combinations of performance characteristics, cost-effectiveness, and sustainability. LFP1LEGAL 49149939.1 1023410-323725 KB / TTbatteries are gaining traction due to their exceptional safety, thermal stability, and long cycle life. LFP, which uses iron (Fe) and phosphate (PO4) as its key components, is inherently safer than other chemistries, with a lower risk of thermal runaway, which can lead to fires or explosions. While LFP batteries offer lower energy density compared to NMC, recent innovations have enhanced their performance, making their use a viable option for the manufacture of affordable electric vehicles and large-scale energy storage systems.

[0005] Li, in particular, is a critical raw material used in the production of new batteries, and its demand is expected to rise sharply over the coming decades. Conventional Li extraction processes, such as mining, are not only environmentally invasive but also characterized by long development timelines, high capital intensity, and geographically concentrated supply chains, which limit their ability to meet growing demand in a sustainable and timely manner. Recycling battery waste provides a concentrated, readily available source of Li with significantly shorter supply cycles and lower environmental footprint compared to primary mining, offering a more sustainable alternative to primary Li extraction, reducing the environmental impact and the need for new mining operations.

[0006] The efficient extraction and purification of Li from LFP black mass present unique challenges due to the complexity of separating Li from other materials, such as Fe, phosphorus (P), and common impurities such as aluminum (Al), fluoride (F"), calcium (Ca), and magnesium (Mg) in a selective and cost-effective manner. Current methods for recycling LFP black mass typically rely on hydrometa II urgica I processes, such as leaching, and pyrometallurgical methods like smelting, to recover Li. However, these processes often suffer from inefficiencies, high energy consumption, and incomplete separation of Li from impurities. Moreover, some techniques may not achieve the required high-purity Li that is needed for new battery production.

[0007] As presented in the study by Hongkai Li, et al. titled "Multi-perspective evaluation on spent lithium iron phosphate recycling process: For next-generation technology option" in 2024, there are four main routes that are technically feasible: (1) the pyrometallurgical recovery process, and (2) the direct regeneration process; (3) the hydrometa I lurgica I total leaching recovery process, (4) the hydrometallurgical selective lithium extraction recovery process. Pyrometallurgical recycling of LFP black mass faces significant challenges due to Li losses and phosphorus volatility. Li can volatilize at high temperatures, making recovery inefficient, or it may report to the slag phase, requiring additional processing to extract it.2LEGAL 49149939.1 1023410-323725 KB / TTIn some cases, Li forms undesirable alloys with Fe, complicating separation. Phosphorus volatility further complicates recovery, as it can be lost as gas emissions or require complex capture methods. These factors, combined with the high energy consumption and environmental concerns of pyro-processing, make it less favorable compared to hydrometallurgical approaches for high-purity Li recovery.

[0008] Direct recycling methods involve the reuse of battery materials without undergoing extensive chemical processing. These methods aim to preserve the structural integrity of the original cathode material, making it possible to regenerate the battery directly for reuse. However, challenges include material degradation, impurity accumulation, and variability in battery state-of- health, which complicate consistent recovery. Maintaining Li balance is crucial, as depletion during cycling affects performance, requiring controlled reintroduction. Additionally, binder degradation and electrode integrity pose technical hurdles, while variations in battery composition hinder standardization. Despite its promise, direct recycling remains an immature technology, needing further optimization for scalability, cost-effectiveness, and reliable electrochemical performance.

[0009] The hydrometallurgical method involves the leaching of black mass, followed by selective metal separation from the leaching solution. The solution is then purified to produce different valuable products. For example, in the paper by Cai, G., et al. titled "Process Development for the Recycle of Spent Lithium-Ion Batteries by Chemical Precipitation" published in 2014, it discusses complete dissolution of LFP. It is dissolved in an acidic solution, with a suggestion that it can be completely dissolved in 120 minutes using a mixture of 4 mol / L sulfuric acid (H2SO4) and 2% hydrogen peroxide (H2O2) at 60°C. The solvent mass is eight times greater than the mass of the cathode material to promote complete dissolution, with H2O2 acting as an oxidizing agent to convert Fe2+to Fe3+, enhancing the dissolution efficiency. After dissolution, Li and Fe are separated and recovered through selective precipitation. Since Li salts are more soluble than Fe3+salts, Fe is recovered first, followed by the recovery of Li in a second precipitation step. Aside from requiring excessive amounts of H2SO4 and H2O2, it requires excessive amounts of NaOH for neutralization, thus leading to high process chemical consumption and wastewater generation.

[0010] Other solvents such as HCI and H3PO4 were studied and proposed, such as that described by Shin, E. J., et al. entitled "A green recycling process designed for LiFeP043LEGAL 49149939.1 1023410-323725 KB / TTcathode materials for Li-ion batteries" in 2014. The researchers proposed a method for recycling and re-synthesizing Li FePCk / C electrode materials from commercially available LFP powders. The process begins by annealing the powders at 700°C to decompose carbon sources and oxidize Fe2+to Fe3+, followed by dissolving the powders in a 6 M HCI solution. After stirring the solution and adjusting the pH with NH4OH, amorphous FePCk-xHzO is formed, and further steps are taken to obtain crystalline FePO4-2H2O. The resulting material is then mixed with Li and carbon sources and subjected to heat treatment under reducing conditions at 700°C to produce LFP / C electrode materials. Aside from losing the valuable C in the process, HCI is highly corrosive and emits dangerous vapors, posing safety risks and requiring careful ventilation and protective measures. Both HCI and NH4OH are corrosive to equipment, leading to increased maintenance costs and potential damage to reactors and other equipment. Moreover, handling and disposing of these hazardous chemicals require specialized procedures to avoid environmental contamination and comply with regulatory standards.

[0011] In the hydrometallurgical selective Li extraction recovery process, the focus is on selectively extracting Li from LiB waste while minimizing the dissolution of other metals. This process typically involves oxidizing agents and acidic leaching solutions to break down the cathode materials, followed by a selective precipitation process to recover Li salts. By carefully controlling parameters like pH and temperature, this method can isolate Li from other elements, such as Fe and P, thus increasing the purity of the extracted Li. This process faces challenges related to the high consumption of chemicals, such as oxidants, higher impurities such as F“ to deal with, and the need for precise control of reaction conditions to ensure high recovery rates and minimize Fe and P contamination. One such process is described by Ji, et al. in their publication titled "Facile and efficient recovery of Li from spent LiFePO4 batteries via air oxidation-water leaching at room temperature" in 2022, which describes a method that combines air oxidation and water leaching at room temperature, allowing for selective Li extraction. The key highlights include the achievement of a 99.3% Li recovery under optimized conditions (pH 3.5, air flow rate of 600 mL / min, liquid-to-solid ratio of 10 mL / g, temperature of 25°C, and a 5-hour leaching time). The process selectively leaches Li while only dissolving minimal amounts of Fe and P. However, industrial scalability is uncertain due to the need for strict process control. Even small pH variations (e.g., shifting from 3.5 to 4) significantly reduce Li leaching efficiency, while lowering pH below 3.5 could increase Fe and P dissolution, compromising purity. Maintaining these exact conditions in4LEGAL 49149939.1 1023410-323725 KB / TTlarge-scale continuous operations with varying feed compositions is a major technical challenge, and process stability must be addressed before commercialization. Additionally, solid-liquid separation efficiency, reagent recycling strategies, and economic feasibility must be carefully optimized to make the process practical for industrial adoption.

[0012] Other approaches were studied wherein the reagent acts as both leaching and oxidizing agent. Such a method was proposed by Shentu, H., et al. in their paper "A fast and efficient method for selective extraction of lithium from spent lithium iron phosphate battery" published in 2021, wherein the reagent was ammonium persulfate. However, the cost of this reagent is 10-20 times higher than those of H2SO4, which hinders its application at large-scale.

[0013] A critical aspect that has not been addressed is the presence of impurities, more importantly, F" and its effective removal. In LFP materials, F" is commonly found as LiPFe, a highly reactive element that can form stable complexes with other metals during the leaching process. This leads to contamination of the leachate, complicating the subsequent recovery of Li and requiring additional purification steps. Without efficient F" removal, enabling battery-grade Li is difficult, as residual F" can degrade the purity of the final Li product, negatively impacting its usability in new battery manufacturing.

[0014] Similarly, Ca and Mg impurities, which are present due to the processing of the original LFP material or as trace elements in the battery, or as a result of crosscontamination, could complicate the purification of the Li. Removal of Ca and Mg to reduce their concentration to very low levels such that the Li product is of high purity is typically done through ion-exchange processes. However, due to the high concentration of Ca and Mg in the leachate, ion-exchange (IX) becomes cost-intensive, requiring large amounts of resin and frequent regeneration. This not only increases operating costs but also adds complexity to the overall process. If not efficiently removed, residual Ca and Mg can precipitate during Li recovery, further contaminating the final product and reducing its suitability for battery-grade applications. Addressing this issue in a cost-effective manner is essential to making LFP recycling economically viable.

[0015] Thus, although various processes for the recovery of lithium from lithium iron phosphate (LFP) battery waste are known, improvements are desired. In particular, there is a growing need for a more efficient, scalable, and sustainable method to recover and5LEGAL 49149939.1 1023410-323725 KB / TTpurify Li from LFP black mass. Such a process must increase Li recovery yield while enabling production of high-purity lithium suitable for reuse in battery materials.SUMMARY OF THE DISCLOSURE

[0016] In accordance with one aspect of the present invention, there is provided a method for processing lithium iron phosphate (LFP) black mass that includes the steps of: (a) leaching the LFP black mass in a solution comprising an acid and water, under nonoxidizing conditions such that iron (Fe) is maintained in a ferrous state (Fe2+); (b) separating carbon residue from the solution; and (c) removing fluoride ions from the solution, wherein removing the fluoride ions includes a first stage impurity removal step, followed by a second stage impurity removal step. The first stage impurity removal step includes: adjusting the solution using a first alkali to a first predetermined pH range to precipitate a first set of impurities as a first set of impurity precipitates, and separating the first set of impurity precipitates from the solution to form a Stage 1 solution. The second stage impurity removal step includes adjusting the Stage 1 solution using a second alkali to a second predetermined pH range to precipitate a second set of impurities as a second set of impurity precipitates, and separating the second set of impurity precipitates to form a Stage 2 solution. The first set of impurities is different from the second set of impurities.

[0017] Other technical advantages may become readily apparent to one of ordinary skill in the art after review of the following figures and description.BRIEF DESCRIPTIONS OF THE DRAWINGS

[0018] For a better understanding of the embodiments described herein and to show more clearly how the embodiments may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which:

[0019] FIG. 1 is a flow diagram of a conventional hydrometallurgical total leaching process for LFP black mass processing;

[0020] FIG. 2 is a flow diagram of a conventional hydrometallurgical selective leaching process for LFP black mass processing; and6LEGAL 49149939.1 1023410-323725 KB / TT

[0021] FIG. 3 is a flow diagram of a process for lithium recovery from LFP black mass with enhanced impurity removal, exemplary of an embodiment of the present invention.

[0022] Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale.DETAILED DESCRIPTION

[0023] The present disclosure introduces an approach to Li recovery and F" removal, from LFP black mass, enabling high-purity Li product while enhancing both economic feasibility and environmental sustainability. Embodiments of the present invention focus on the efficient recovery of Li while enabling the production of high-purity Li compounds suitable for use in the manufacturing of new batteries and other industrial applications.

[0024] In particular, at least one embodiment introduces a tailored leaching process configured to maintain phosphate (P043-) in solution, which in turn enables the selective separation of F", Ca, and Mg in subsequent purification steps. The disclosed process is designed to improve efficiency, cost-effectiveness, and environmental sustainability, contributing to the development of a circular economy for lithium-ion batteries (LiBs).

[0025] Directional terms such as "top," "bottom," "upwards," "downwards," "vertically," and "laterally" are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment. The use of the word "a" or "an" when used herein in conjunction with the term "comprising" may mean "one," but it is also consistent with the meaning of "one or more," "at least one" and "one or more than one." Any element expressed in the singular form also encompasses its plural form. Any element expressed in the plural form also encompasses its singular form. The term "plurality" as used herein means more than one, for example, two or more, three or more, four or more, and the like.

[0026] In this disclosure, the terms "comprising", "having", "including", and "containing", and grammatical variations thereof, are inclusive or open-ended and do not exclude additional, un-recited elements and / or method steps. The term "consisting essentially of" when used herein in connection with a composition, use or method, denotes7LEGAL 49149939.1 1023410-323725 KB / TTthat additional elements, method steps or both additional elements and method steps may be present, but that these additions do not materially affect the manner in which the recited composition, method, or use functions. The term "consisting of" when used herein in connection with a composition, use, or method, excludes the presence of additional elements and / or method steps.

[0027] For clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiment or embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. It should be understood at the outset that, although embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the implementations and techniques illustrated in the drawings and described in this disclosure.

[0028] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: "or" as used throughout is inclusive, as though written "and / or"; singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; "exemplary" should be understood as "illustrative" or as a non-limiting example, and not necessarily as "preferred" over other embodiments. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description. It will also be noted that the use of the term "a" or "an" will be understood to denote "at least one" in all instances unless explicitly stated otherwise or unless it would be understood to be obvious that it must mean "one".

[0029] Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For8LEGAL 49149939.1 1023410-323725 KB / TTexample, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

[0030] As used herein, the term "about" when referring to a number or a numerical range means that the number or numerical range referred to is an approximation within experimental variability (or within statistical experimental error), and thus the number or numerical range may vary from, for example, between 1% and 15% of the stated number or numerical range.

[0031] As used herein, the term "comprising" (and related terms such as "comprise" or "comprises" or "having" or "including") includes, but is not limited to, those embodiments, for example, an embodiment of any composition of matter, composition, method, or process, or the like, that "consist of" or "consist essentially of" the described features.

[0032] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of "from 2 to 10" is inclusive of the endpoints, 2 and 10, and all the intermediate values). The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and / or values. As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about," may not be limited to the precise value specified, in some cases. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. The modifier "about" should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression "from about 2 to about 4" also discloses the range "from 2 to 4." The term "about" may refer to plus or minus 10% of the indicated number. For example, "about 10%" may indicate a range of 9% to 11, and "about 1" may mean from 0.9-1.1. Other meanings of "about" may be apparent from the context, such as rounding off, so, for example "about 1" may also mean from 0.5 to 1.4.9LEGAL 49149939.1 1023410-323725 KB / TT

[0033] When amounts, concentrations, dimensions and other parameters are expressed in the form of a range, a preferable range, an upper limit value, a lower limit value or preferable upper and limit values, it should be understood that any ranges obtainable by combining any upper limit or preferable value with any lower limit or preferable value are also specifically disclosed, irrespective of whether the obtained ranges are clearly mentioned in the context.

[0034] FIG. 1 is a flow diagram of a conventional hydrometallurgical total leaching process 100 for LFP black mass processing. The depicted process flow diagram illustrates an existing hydrometallurgical total leaching process for LFP black mass processing.

[0035] In this process, LFP black mass 10 is leached (step 102) with a solution of H2SO4 11 and H2O (water) 12.

[0036] After the required reaction time has elapsed, the acid slurry is filtered (step 104) to separate the acidic solution containing Li, Fe2+, Fe3+, PO4, F", Ca, Mg, and other impurities from the carbon residue 13.

[0037] The acidic solution is then treated with hydrogen peroxide (H2O2) 14 as the oxidizing agent for Fe2+to Fe3+, then the pH is adjusted to 2.5 with ammonium hydroxide 15 to precipitate iron (step 106) as FePO4-2H2O.

[0038] After the required pH and reaction time are maintained, the pH-adjusted slurry is filtered (step 107) to separate the Li solution containing Al, some Fe3+, some PO4, F“, Ca, and Mg from the FePO4.2H2O 16.

[0039] The pH-adjusted solution is then treated with sodium hydroxide 17 solution for Al precipitation (step 108), then filtered (step 109) to separate the Li solution containing F", Ca, and Mg from the Al precipitate 18.

[0040] The Li solution is then treated with NaOH 19 to adjust (step 110) the pH to precipitate a portion of Ca, and Mg primarily as Ca(OH)2 and Mg(OH)2 with some CaF2 and MgF2. The slurry is then filtered (step 111) to separate the Ca / Mg precipitate (mostly as hydroxides) 20 from the Li solution containing a portion of F", Ca, and Mg.10LEGAL 49149939.1 1023410-323725 KB / TT

[0041] The Li solution containing a portion of F", Ca, and Mg is then further purified (step 112) to remove the said residual impurities. The purified Li solution thereby generated is then preconcentrated and treated with sodium carbonate (Na2CO3) 21 to precipitate (step 114) U2CO3.

[0042] The resulting slurry is then filtered (step 116) to separate U2CO3 22 from the solution containing sodium sulfate, which then goes to cooling crystallization (step 118). The Glauber's salt slurry is then filtered (step 120) to separate the Glauber's salt crystals 23.

[0043] FIG. 2 is a flow diagram of a conventional hydrometallurgical selective leaching process 200 for LFP black mass processing.

[0044] As shown, LFP black mass 30 is leached in oxidative conditions (step 302) with a solution of H2SO4 or sulfuric acid 31, water 32, and H2O2 33.

[0045] After the required reaction time has elapsed, the acid slurry is filtered (step 204) to separate the acidic solution containing Li, minimal Fe and PO4, F", Ca, Mg, and other impurities from FePO4.2H2O / carbon residue 34.

[0046] The resulting solution is then treated with sodium hydroxide 35 solution for Al precipitation (step 206) then filtered (step 208) to separate the Li solution containing F", Ca, and Mg from the Al precipitate 36.

[0047] The Li solution is then treated with NaOH 37 to adjust (step 210) the pH to precipitate a portion of Ca, and Mg therein as mostly Ca(OH)2 and Mg(OH)2 with some CaF2 and MgF2.

[0048] The slurry is then filtered (step 212) to separate the Ca / Mg precipitate (mostly as hydroxides) 38 from the Li solution containing a portion of F", Ca, and Mg.

[0049] The Li solution containing a portion of F", Ca, and Mg is then further purified (step 214) to remove the residual impurities. The purified Li solution thereby generated is then preconcentrated and treated with Na2CO3 or sodium carbonate 39 to precipitate (step 216) U2CO3.11LEGAL 49149939.1 1023410-323725 KB / TT

[0050] The resulting slurry is then filtered (step 218) to separate U2CO3 40 from the solution containing sodium sulfate, which then goes to cooling crystallization (step 220). The Glauber's salt slurry is then filtered (step 222) to separate the Glauber's salt crystals 41.

[0051] These existing processes involve oxidizing Fe2+to Fe3+to facilitate Fe removal by formation of FePO4 during pH adjustment at 2.5. While at this pH almost all of the PO4 is precipitated, most if not all of Al and F" stay in solution, which makes F" removal challenging.

[0052] In contrast, embodiments of the present disclosure maintain iron in its Fe2+state under non-oxidizing conditions, thereby preventing ferric phosphate formation and allowing phosphate to remain available in solution. This promotes preferential precipitation of aluminum fluorophosphate species prior to any ferrous phosphate precipitation and thus the removal of F". This is achieved by controlling leaching conditions to eliminate the need for an oxidant while maintaining a high Li leaching extent.

[0053] In existing processes where Fe2+is oxidized to Fe3+to facilitate Fe removal via FePO4 precipitation, the simultaneous removal of PO4 affects the behavior of other impurities. In addition to Al and F", high levels of Ca and Mg remain in solution, making their removal challenging. At high pH in the absence of PO4, Ca and Mg form insoluble hydroxide compounds, Ca(OH)2 and Mg(OH)2, respectively; however, their solubilities are significantly higher than their corresponding phosphate forms.

[0054] As a result, even at high pH, Ca and Mg removal remains inefficient, and it is difficult to achieve sufficiently low Ca and Mg concentrations for high-purity Li recovery resulting in the need for ion-exchange, which becomes costly at high Ca and Mg concentrations due to frequent resin regeneration and increased chemical consumption.

[0055] In contrast, embodiments of the present disclosure maintain Fe in its Fe2+state, preventing premature PO4 precipitation and enabling controlled Ca and Mg removal through the formation of Ca3(PO4)2 and Mgs(PO4)2 which have significantly lower solubility than their corresponding fluoride and hydroxide forms.

[0056] FIG. 3 is a flow diagram of a process 300 for lithium recovery from LFP black mass with enhanced impurity removal, exemplary of an embodiment of the present invention.12LEGAL 49149939.1 1023410-323725 KB / TT

[0057] The process starts with leaching LFP black mass 50 in a solution of H2SO451 and water 52, (step 302) under non-oxidizing conditions, for example, in the absence of an oxidizing agent, to maintain Fe as Fe2+state under non-oxidizing conditions, thereby preventing ferric phosphate formation and allowing phosphate to remain available in solution.

[0058] The next step is separating the carbon residue 53 from the acidic solution via a separation or filtering step (step 304).

[0059] The next task is to remove F" from the acidic solution. In the depicted embodiment, this involves a two-stage impurity removal and associated filtering steps.

[0060] The first stage includes an impurity removal (step 306) labelled ("Impurity Removal - Stage 1") that includes adjusting the pH of the acidic solution to a predetermined pH range in order to precipitate a first set of impurities using an alkali 54 such as NaOH. In the depicted embodiment of FIG. 3, the alkali used is NaOH but in other embodiments, other alkali such as lithium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, or combinations thereof may also be used. The illustrated use of NaOH is thus only by way of example and not limiting. The first set of impurities includes Al, F~ and PO4, which are removed through formation and precipitation of aluminum fluorophosphate compounds. The pH range may be about 2.0-8.0, about 3.0-7.0, or about 4.0-6.0.

[0061] The process 300 then proceeds to the next step in the first stage impurity removal to separate (step 308) a first set of impurity precipitates 55 (e.g., aluminum fluorophosphate compounds) from the Stage 1 solution using a conventional solid-liquid separation step, such as filtration, settling, thickening, or centrifugation

[0062] The process 300 then proceeds to a second stage that also includes an impurity removal step (step 310) labelled ("Impurity Removal - Stage 2") which involves adjusting the pH of the Stage 1 solution to precipitate a second set of impurities (i.e., Ca and Mg in this embodiment) using an alkali 56, such as NaOH, lithium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, or combinations thereof. As noted above for the first stage, the depicted use of NaOH in the second stage is also only an example of an alkali that may be used and not intended to be limiting. Under13LEGAL 49149939.1 1023410-323725 KB / TTthese conditions, Ca and Mg are preferentially precipitated as Ca3(PO4)2 and Mg3(PO4)2, respectively, resulting in a Stage 2 solution.

[0063] The second stage impurity removal also includes filtering to separate (step 312) Ca and Mg containing second set of impurities precipitates from the Stage 2 solution. As may be appreciated, Ca and Mg are precipitated mainly in the form of phosphates - i.e., Ca3(PO4)2and Mg3(PO4)2 respectively.

[0064] Crystallization (step 314) is then used to remove sulfate from the purified solution as a sulfate salt, such as sodium sulfate (Na2SO4) which is then separated (step 316) from the Li containing solution.

[0065] A precipitation step (step 318) is used to precipitate Li, which is then separated or filtered (step 320) from the solution and provided as high-purity Li product 59. The process 300 may then continue back to the precipitation step 318 for further Li precipitation.

[0066] In some embodiments, the acid leaching step 302 may also be configured in a co-current or countercurrent arrangement, operating either in a batch or continuous mode.

[0067] In one embodiment of process 300, the black mass 50 may be generated from recycling of LFP LiB waste. In another embodiment, the black mass may comprise a portion of at least one of the other LiB chemistries, lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), and lithium titanate (LTO). In yet another embodiment, the black mass is derived from one or more of: (i) recycling lithium iron phosphate (LFP) lithium-ion battery waste; and (ii) mixed lithium-ion battery black mass comprising lithium iron phosphate (LFP) in combination with one or more of lithium-ion battery chemistries selected from LCO, LMO, NMC, NCA, and LTO.

[0068] In a variation of an embodiment of process 300, the acid leaching step may be performed at a pulp density of about 50%, or about 40%, or about 30%.

[0069] In another embodiment, acid leaching may be performed at a temperature equal to or less than the boiling point of the slurry such as below about 100 °C, below about 80 °C, below about 60 °C, below about 40 °C.14LEGAL 49149939.1 1023410-323725 KB / TT

[0070] In one aspect of any of the exemplary embodiments of the processes described herein, acid leaching may be performed in less than about 4 hours, less than about 3 hours, less than about 2 hours.

[0071] In one aspect of any of the processes described herein, Stage 1 Impurity Removal may be performed at a pH of between about 2 and about 8, between about 3 and about 7, between about 4 and 6, using a precipitating agent including, but not limited to, lithium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, or combinations thereof;

[0072] In one aspect of any of the processes described herein, Stage 1 Impurity Removal may be performed at a temperature between about 20 °C and about 100 °C, such as between about 50 °C and about 80 °C, such as between about 30 °C and about 40 °C.

[0073] In one aspect of any of the processes described herein, Stage 1 Impurity Removal may be performed in less than about 4 hours, less than about 3 hours, or less than about 2 hours.

[0074] In one aspect of any of the processes described herein, Stage 2 Impurity Removal may be performed at a pH of greater than about 8, or greater than about 9, or greater than about 10, or greater than about 11, using a precipitating agent including, but not limited to, lithium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, or combinations thereof.

[0075] In one aspect of any of the processes described herein, Stage 2 Impurity Removal may be performed at a temperature between about 20 °C and about 100 °C, such as between about 50 °C and about 80 °C, or between about 30 °C and about 40 °C.

[0076] In some embodiments, Stage 2 Impurity Removal may be performed in less than about 4 hours, less than about 3 hours, or less than about 2 hours.

[0077] In some embodiments, sulfate may be removed as a sulfate salt, including, but not limited to, sodium sulfate, Glauber's salt, calcium sulfate, ammonium sulfate, or combinations thereof.15LEGAL 49149939.1 1023410-323725 KB / TT

[0078] In some embodiments, the Li product may comprise lithium hydroxide monohydrate or lithium carbonate with purity suitable for battery manufacture.

[0079] In some embodiments, the separation step in all stages mentioned above is performed by one or more suitable methods, including, but not limited to, gravity settling, decantation, thickening, centrifugation, or filtration.Advantages

[0080] Embodiments of the present invention not only enhance impurity removal efficiency but also eliminate or significantly reduce the need for IX, thereby reducing operating costs and simplifying the overall process while enabling high-purity Li recovery. This process is designed to offer a practical and cost-effective solution for Li recovery and purification, enabling the production of high-purity Li products suitable for reuse in nextgeneration applications including battery manufacturing. The method is tailored to overcome several key challenges faced by existing recycling techniques, particularly impurity removal and cost-efficiency, while maintaining high Li recovery extent, such as:

[0081] (1) Li recovery extent exceeding 95%; (2) practical and efficient F" removal; (3) practical and efficient Ca and Mg removal; (4) lower operating costs; and (5) environmental benefits.

[0082] The formation of aluminum fluorophosphates is the mechanism at which F" is removed. This is enabled by optimizing the leaching conditions to maintain Fe as Fe2+, thereby eliminating the need for an oxidizing agent.

[0083] The formation of Ca3(PO4)2 and Mg3(PO4)2 promotes effective Ca and Mg removal, respectively. This is enabled by optimizing the leaching conditions to maintain Fe in its Fe2+state, reducing premature P04 precipitation and enabling controlled Ca and Mg removal, thereby eliminating or reducing the need for additional purification steps.

[0084] Embodiments of the disclosed the process reduce operating costs by eliminating the need for H2O2, improving economic feasibility.

[0085] Embodiments of the disclosed process also reduced chemical consumption and generation of stable F“-containing solid waste make the process more environmentally sustainable and aligned with circular economy objectives.

[0086] EXAMPLES16LEGAL 49149939.1 1023410-323725 KB / TT

[0087] Example 1: Comparative Acid Leaching of LFP Black Mass Under Oxidizing and Non-Oxidizing Conditions

[0088] Two tests were conducted to evaluate the effect of oxidative versus non-oxidative acid leaching conditions on Li leaching efficiency, acid consumption, and oxidant demand during the leaching of LFP black mass. The tests were performed using the same equipment, leaching setup, temperature range, and acid system, with the primary distinction being the presence or absence of an oxidizing agent.

[0089] In each test, the initial pulp density was approximately 20 wt% solids. Sulfuric acid was added at an acid-to-solid basis of approximately 0.65 g of H2SO4 (100% basis) per g of black mass.

[0090] In the first test, Test 1A, an oxidative acid leaching procedure was carried out. Deionized water was added to a suitably sized reaction vessel and agitated. Concentrated sulfuric acid was then added gradually while maintaining the slurry temperature in the range of approximately 50-60°C. Once the acid addition was complete, LFP black mass was added to the slurry and allowed to react for approximately 1 hour.

[0091] Following the initial leaching period, a hydrogen peroxide solution was introduced into the slurry at a controlled rate to promote oxidation of dissolved iron species. The hydrogen peroxide was added at an F C -to-black mass basis of 0.1 (100% active basis). After completion of the oxidant addition, the slurry was maintained at temperature for an additional 1 hour. The slurry was then cooled, filtered to separate the leach solution from the solid residue, and the filtrate and residue were collected for analysis.

[0092] In the second test, Test IB, an acid leaching procedure was conducted under non-oxidizing conditions in accordance with the present disclosure. The same reaction vessel, acid system, black mass feed, temperature range, and leaching duration as in Test 1A were employed. However, no oxidizing agent was added during or after the acid leaching step.

[0093] The slurry was maintained under otherwise comparable conditions for approximately 1 hour, after which it was cooled and filtered to separate the leach solution from the solid residue. The filtrate and residue were collected for analysis.17LEGAL 49149939.1 1023410-323725 KB / TT

[0094] The filtrates and solid residues from Tests 1A and IB were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). Acid and hydrogen peroxide addition levels were controlled and recorded for each test. The extent of leaching for Li and selected elements was determined based on the measured concentrations in the filtrate and residue.

[0095] Table 1: Comparative Leaching Performance and Reagent ConsumptionH202(100%) Extent of Leaching Leaching / Black mass Li Fe P Cu Al Test 1A - Oxidative 0.1 -100% 99% 97% 86% 94% Test IB - Non- -100% 99% 68% <1% 70%oxidizing

[0096] The results from the comparative leaching tests demonstrate that both Test 1A and Test IB achieved effective Li leaching under the tested conditions, with Li exhibiting an extent of leaching of approximately 100% in both cases. Importantly, the amount of sulfuric acid used in Test 1A and Test IB was the same, thereby isolating the effect of the oxidizing agent on leaching behavior and reagent consumption.

[0097] In Test 1A, hydrogen peroxide was added in an amount calculated based on the stoichiometric requirement for oxidation of dissolved iron species from Fe2+to Fe3+. While this oxidative condition resulted in extensive dissolution of Li, it was also associated with increased dissolution of impurities. In contrast, Test IB achieved approximately complete Li extraction under non-oxidizing conditions while significantly reducing co-dissolution of impurities, thereby eliminating the need for hydrogen peroxide addition and reducing overall reagent consumption without compromising Li recovery.

[0098] These results indicate that oxidative conditions are not required to achieve effective Li leaching from LFP black mass and that non-oxidizing acid leaching, as disclosed herein, can provide approximately complete Li extraction while intentionally limiting impurity dissolution, reducing or eliminating oxidant demand and simplifying reagent usage.

[0099] Example 2: Comparative Impurity Removal Following Oxidizing and Non-Oxidizing Acid Leaching18LEGAL 49149939.1 1023410-323725 KB / TT

[0100] Two sets of impurity removal tests were conducted to evaluate the effect of oxidizing versus non-oxidizing acid leaching conditions on impurity behavior during subsequent purification stages. In particular, the tests were designed to assess F~, Al, Ca, and Mg behavior following Stage 1 and Stage 2 impurity removal. The tests were performed using the same equipment, reagents, and general operating conditions, with the primary distinction being the oxidation state of iron in solution following leaching, specifically Fe3+under oxidizing conditions and Fe2+under non-oxidizing conditions.

[0101] Leach filtrates obtained from oxidative acid leaching (Test 1A) and non-oxidizing acid leaching (Test IB) were first analyzed to establish baseline impurity concentrations prior to any impurity removal steps. The results are summarized in Table 2.

[0102] Table 2: Concentration in Leach FiltrateConcentration in Leach Filtrate (mg / L) LeachingFe P Cu Al F Ca Mg Test 1A - Oxidative 33,400 19,500 27,600 12,000 1500 780 170 Test IB - Non33,000 13,700 150 9,100 1400 530 170oxidizing

[0103] Leach filtrates from Tests 1A and IB were subjected to Stage 1 impurity removal by adjusting the pH to approximately about 4-5 using a base. The resulting slurries were reacted under controlled conditions and filtered to separate precipitated solids from the clarified filtrate. Stage 1 impurity removal is configured to selectively reduce Al, Cu, and F" concentrations while maintaining iron predominantly in solution.

[0104] Under non-oxidizing leaching conditions, iron remains predominantly in the ferrous (Fe2+) state and phosphate is retained in solution. This retained phosphate enables selective impurity partitioning during Stage 1 impurity removal, promoting the formation and precipitation of aluminum fluorophosphate species while limiting premature phosphate depletion. The comparative results below illustrate the effect of this redox-controlled chemistry on impurity removal behavior.

[0105] Table 3: Concentration in Stage 1 Impurity Removal Filtrate19LEGAL 49149939.1 1023410-323725 KB / TTConcentration in Stage 1 Impurity Removal Filtrate (mg / L) Stage 1 Impurity RemovalFe P Cu Al F Ca Mg Test 2A - Oxidative 75 16 8 400 420 330 130Test 2B - Non-oxidizing 21,000 350 <1 3 17 300 140

[0106] Under oxidative leaching conditions (Test 2A), iron and phosphate were substantially removed during Stage 1 impurity removal, thereby substantially depleting phosphate from solution, limiting fluoride removal and leaving elevated concentrations of Al and F~ in solution. In contrast, under non-oxidizing leaching conditions (Test 2B), iron remained predominantly in the ferrous state and phosphate was retained in solution, promoting the formation and removal of aluminum fluorophosphate species, resulting in significantly reduced aluminum and fluoride concentrations during Stage 1 impurity removal.

[0107] The clarified filtrates obtained after Stage 1 impurity removal from Tests 2A and 2B were subjected to Stage 2 impurity removal by further pH adjustment to promote precipitation of alkaline earth metal impurities and residual iron species. Following reaction and solid-liquid separation, the filtrates were analyzed by ICP-OES.

[0108] Table 4: Concentration in Stage 2 Impurity Removal FiltrateConcentration in Stage 2 Impurity Removal Filtrate (mg / L) Stage 2 Impurity RemovalFe P F Ca Mg Test 3A - Oxidative <1 15 400 270 110Test 3B - Non-oxidizing <1 30 <1 <1 <1

[0109] The results demonstrate that retention of phosphate following non-oxidizing leaching and Stage 1 impurity removal enabled effective removal of Ca and Mg during Stage 2 impurity removal, resulting in Ca, Mg, and F" concentrations below 1 mg / L, which is below the detection limit of the ICP-OES method. In contrast, filtrates derived from oxidative leaching conditions retained elevated concentrations of Ca, Mg, and F" following Stage 2 treatment.

[0110] Collectively, the results demonstrate that non-oxidizing acid leaching, as disclosed herein, enables staged impurity removal in which aluminum and fluoride are20LEGAL 49149939.1 1023410-323725 KB / TTpreferentially reduced during Stage 1 impurity removal, followed by effective Ca and Mg removal during Stage 2 impurity removal. As a result, the filtrate obtained following Stage 2 impurity removal under non-oxidizing conditions exhibited sufficiently low impurity concentrations such that additional ion-exchange or polishing steps typically required in conventional LFP recycling flowsheets were not required to achieve the reported impurity levels.

[0111] These results confirm that maintenance of iron in the ferrous state under nonoxidizing conditions enables staged, phosphate-mediated impurity removal, first reducing aluminum and fluoride during Stage 1 and subsequently reducing Ca and Mg during Stage 2. This mechanistic distinction from oxidizing leach systems underpins the reduced reliance on downstream ion-exchange or polishing steps.

[0112] Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages.

[0113] Persons skilled in the art will appreciate that there are yet more alternative implementations and modifications possible, and that the above examples are only illustrations of one or more implementations. The scope, therefore, is only to be limited by the claims appended hereto and any amendments made thereto.21LEGAL 49149939.1 1023410-323725 KB / TT

Claims

CLAIMSWhat is claimed is:

1. A method for processing lithium iron phosphate (LFP) black mass, the method comprising the steps of:(a) leaching the LFP black mass in a solution comprising an acid and water, under non-oxidizing conditions such that iron (Fe) is maintained in a ferrous state (Fe2+);(b) separating carbon residue from the solution; and(c) removing fluoride ions from the solution, said removing the fluoride ions comprising:(i) a first stage impurity removal step comprising:(1) adjusting the solution using a first alkali, to a first predetermined pH range, to precipitate a first set of impurities as a first set of impurity precipitates; and(2) separating the first set of impurity precipitates from the solution to form a Stage 1 solution;(ii) a second stage impurity removal step comprising:(1) adjusting the Stage 1 solution using a second alkali, to a second predetermined pH range, to precipitate a second set of impurities as a second set of impurity precipitates; and (2) separating the second set of impurity precipitates to form a Stage 2 solution;wherein the first set of impurities is different from the second set of impurities.

2. The method of claim 1, further comprising removing sulfate from the Stage 2 solution by crystallizing to form sodium sulfate crystals.

3. The method of claim 2, further comprising separating the sodium sulfate crystals to form a lithium-containing solution.

4. The method of claim 3, further comprising precipitating lithium from the lithium- containing solution to form a lithium product.22LEGAL 49149986.1 1023410-323725 KB / TT5. The method of claim 1, wherein the acid comprises sulfuric acid.

6. The method of claim 1, wherein the first predetermined pH range is 2.0-8.0.

7. The method of claim 6, wherein the first predetermined pH range is 3.0-7.0.

8. The method of claim 7, wherein the first predetermined pH range is 4.0-6.0.

9. The method of claim 1, wherein the first alkali comprises NaOH and the second alkali comprises NaOH.

10. The method of claim 1, wherein the first set of impurities comprises aluminum, fluoride, and phosphate.

11. The method of claim 10, wherein said aluminum, fluoride, and phosphate are precipitated as aluminum fluorophosphate compounds.

12. The method of claim 10, wherein the leaching under said non-oxidizing conditions maintains phosphate (PO43-) in the solution.

13. The method of claim 1, wherein the second predetermined pH range is 8.0-14.0.

14. The method of claim 13, wherein the second predetermined pH range is 9.0-14.0.

15. The method of claim 14, wherein the second predetermined pH range is 10.0-14.0.

16. The method of claim 15, wherein the second predetermined pH range is 11.0-14.0.

17. The method of claim 1, wherein the second set of impurities comprises one or more of calcium and magnesium.

18. The method of claim 17, wherein the second set of impurity precipitates comprises one or more of calcium phosphate and magnesium phosphate.

19. The method of claim 4, wherein the lithium product comprises one of LiOH.H2O and IJ2CO3.

20. The method of claim 1, wherein said leaching under said non-oxidizing conditions causes the iron to remain in a predominantly ferrous state and phosphate to be23LEGAL 49149986.1 1023410-323725 KB / TTretained in the solution, thereby promoting formation and removal of aluminum fluorophosphate species and reducing aluminum and fluoride concentrations during the first stage impurity removal step.

21. The method of claim 1, wherein the leaching is performed in a co-current or counter-current arrangement, operating either in batch or continuous mode.

22. The method of claim 1, wherein the LFP black mass is derived from one or more of:(a) recycling lithium iron phosphate (LFP) lithium-ion battery waste;(b) mixed lithium-ion battery black mass comprising lithium iron phosphate (LFP) in combination with one or more of lithium-ion battery chemistries selected from the group consisting of: lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), and lithium titanate (LTO).

23. The method of claim 1, wherein the leaching is performed at a pulp density of one of: 30%, 40% and 50%.

24. The method of claim 1, wherein said leaching is performed at a temperature equal to or less than about 100°C.

25. The method of claim 24, wherein the temperature is below 80°C.

26. The method of claim 25, wherein the temperature is below 60°C.

27. The method of claim 1, wherein at least one of: the leaching and the first stage impurity removal step is completed in a period of less than about 4 hours.

28. The method of claim 27, wherein the period is less than about 3 hours.

29. The method of claim 28, wherein the period is less than about 2 hours.

30. The method of claim 1, wherein one or more of the first stage impurity removal step and the second stage impurity removal step, uses a precipitating agent comprising one or more of: lithium hydroxide, potassium hydroxide, sodium24LEGAL 49149986.1 1023410-323725 KB / TTcarbonate, potassium carbonate, lithium carbonate, sodium hydroxide, and combinations thereof.

31. The method of claim 1, wherein each of the first stage impurity removal step and the second stage impurity removal step is performed at a temperature between about 20°C and about 100°C.

32. The method of claim 31, wherein the temperature is between about 50°C and about 80°C.

33. The method of claim 32, wherein the temperature is between about 30°C and about 40°C.

34. The method of claim 2, wherein said removing sulfate comprises crystallizing the sulfate as one or more of: sodium sulfate, Glauber's salt, calcium sulfate, ammonium sulfate, and combinations thereof.

35. The method of claim 4, wherein the lithium product is one of: lithium hydroxide monohydrate and lithium carbonate having a purity of at least 99%.

36. The method of claim 1, wherein each of: said separating carbon residue from the solution; said separating the first set of impurity precipitates; said separating the second set of impurity precipitates; and said separating sodium sulfate crystals is performed using one or more of: gravity settling, decantation, thickening, centrifugation, filtration, and combinations thereof.25LEGAL 49149986.1 1023410-323725 KB / TT

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