Black mass lithium recovery

Abstract

The present invention concerns a process for recycling lithium batteries, said process comprising: a. providing one or more lithium batteries; b. dry shredding the one or more lithium batteries; d. separating copper and aluminium foils from the shredded lithium batteries to obtain a black mass; c. subjecting the black mass to a first temperature treatment to remove electrolyte, volatile organics and PVDF to obtain a first temperature treated black mass, said first temperature treatment has a temperature of at most 480°C; e. subjecting the first temperature treated black mass to a second temperature treatment to liberate Li from the cathode active material (CAM) and obtain a second temperature treated black mass, said second temperature treatment has a temperature of at least 500°C; f. leaching the second temperature treated black mass with CO2 and water to obtain an aqueous LiHCO3 solution and a residue comprising graphite.

Description

Black mass lithium recoveryField of the invention

[0001] The present invention is in the field of lithium battery recycling, in particular it relates to a process for black mass production and recovery from lithium from said black mass.Background of the invention

[0002] The production of black mass, a critical intermediate in the recycling of spent batteries, has garnered significant attention due to the increasing demand for sustainable and efficient methods to recover valuable metals. Black mass typically contains a mixture of critical metals such as lithium, cobalt, nickel, manganese, and graphite, which are essential for manufacturing new batteries. Various methods have been developed to process black mass, each aiming to optimize the recovery and purity of these metals. In hydrometallurgical routes, black mass is often leached in a combination of an inorganic acid, e.g. sulfuric acid, and a reducing agent to dissolve the soluble elements after which the insoluble elements (e.g. graphite) are separated by filtration. Metals are then separated from each other and / or purified using pH adjustment, or with solvent extraction technologies. These standard methods have the disadvantage that lithium is then only recovered ‘end of pipe’ (i.e. in the raffinate stream of the last solvent extraction unit) where it is already diluted to a certain extent due to the addition of reagents during previous process steps. This leads to lower lithium recovery yields as this final solution often contains lithium levels of arounds the solubility limit, which means that precipitation of lithium as a carbonate will not be effective.

[0003] Currently, industrial recycling technology primarily focuses on nickel-cobalt-based batteries such as NMC due to the high economic value of lithium, nickel and cobalt while neither graphite nor Li are recovered due to their perceived lower economic value. Graphite represents 14 to 22 % of a LIBs weight and therefore, it should be recovered to satisfy the expected EU recycling requirements. In addition, the EU considers Ni and Cu as strategic raw materials while Co, Li, Mn, natural graphite, and bauxite are categorized as critical raw materials highlighting the importance of developing viable recycling strategies for these elements. However, this process typically relies on strong acids for metal extraction and a lot of other chemicals which pose environmental risks and involve complex waste management. More sustainable alternative technologies have been explored to offer a more environmentally friendly approach to recycle the batteries, including lithium recovery from NMC or LFP type batteries using water and CO2 as an extraction agent.

[0004] Recycling of lithium without complete dissolution of black mass (e.g. using a selective and simple mild-acid leaching with CO2) usually leads to low lithium recovery yields as it depends on how the black mass was produced or pretreated before the leaching occurs. A portion of this lithium might get lost during the different pretreatment steps or cannot be made available for leaching.

[0005] A battery consists of a cathode, anode and electrolyte, but also contains a separator, carrier, binders, casing poles, wiring and possibly a printed circuit board.

[0006] LiPFe is the most used salt in the electrolyte for commercial Li-ion cells; if a wet shredding of the batteries will be performed, some Li will be lost due to solubility of LiPFe in water. The electrolyte is dissolved in an organic solvent that is usually a mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate and solvent can be evaporated to separate it from black mass.

[0007] Polyvinyl difluoride (PVDF) is the organic component that acts as a binder to bond the cathode powder to the aluminium foil. To a certain extent, its degradation is required to obtain a good separation between the cathode material and the aluminium layer. However, at high temperature, PVDF starts todecompose and LiF can be formed, which is due to its low solubility detrimental for lithium removal without complete dissolution of the black mass.

[0008] During battery production, the active materials are coated on a carrier film. For Li-ion batteries, this is a copper foil for the graphite anode and an aluminium foil for LiMeC>2 (with Me = Nickel, Cobalt and / or Manganese) at the cathode. A high-temperature pyrolysis of black mass can lead to the generation of LiAIC>2 as a by-product; during downstream lithium recovery, LiAIC>2 will not dissolve, lowering the overall Lithium recovery yield.

[0009] On the other hand, a high temperature treatment of black mass is required if an upfront removal of lithium from black mass is targeted. In battery recycling, optimal carbothermal conditions can convert lithium compounds in the black mass into water-soluble forms that promote selective and complete lithium leaching. The recovery of lithium in the leaching process is influenced by the solubility of the lithium compounds formed during the heat treatment of black mass. At 25 °C, Li2COs has a solubility of 1.3 g / 100 mL, while Li2O is highly soluble at 201 g / 100 mL, and metallic Li reacts directly with water. Above 718 °C, Li2CC>3 becomes thermodynamically unstable and decomposes into Li2O.

[0010] The target temperature is a critical factor in the pyrolysis process and complex transformations occur in the NMC black mass during pyrolysis. The NMC cathode undergoes partial reduction, with some elements fully reduced to metals or alloys, while the others remain as lower oxidation state metal oxides. In the cathode, metals are initially present in oxidized states such as Li+1, Ni27Ni3+, Co3+, and Mn4+. During pyrolysis, transition metals like Ni, Co, and Mn are reduced, while lithium (as Li2<D) reacts with CO2 to form Li2CC>3. A portion of Li2COs thermally decomposes again at higher temperatures into Li2<D. Nickel and Cobalt are reduced and form a Ni-Co alloy whereas Manganese is partially reduced and remains as MnO.

[0011] Document FI127830B discloses a method for preprocessing the alkaline black mass derived from spent alkaline batteries. The process involves a heat treatment that reduces the pH of the black mass, facilitating subsequent leaching processes for metal recovery. By heating the black mass in oxidative conditions, substances such as humidity, ammonia, carbon, paper, and plastics are removed, resulting in a more homogeneous material suitable for efficient leaching. This approach enhances the recovery rates of metals like manganese and zinc.

[0012] Document FI20236120A1 describes a method for selective leaching of lithium from lithium-ion battery waste, using CO2, maintaining the temperature in the mixture in the range of 120-250°C, requiring pressure vessels.

[0013] International patent application WO2022219221A1 describes a method for extracting metals from pretreated black mass, including an acid leaching step carried out in a solution containing sulfuric acid. This method aims to improve the efficiency and environmental sustainability of recycling lithium-ion batteries using pretreated black mass wherein a fraction of non-metallic material is separated from the black mass and a pretreated black mass containing anode and cathode materials is recovered.

[0014] Document EP4245869 describes a process to leach black mass in sulfuric acid, whereby graphite does not dissolve and is separated by filtration. After removal of impurities, the resulting lithium sulfate solution is converted into lithium hydroxide by electrolysis.

[0015] Document CN112591773 describes a method for preparing battery-grade lithium carbonate, starting from pretreated black mass which is leached in water and whereby the resulting lithium sulfate solution is treated with sodium carbonate to precipitate a crude lithium carbonate. This crude product isreslurried and treated with CO2 to obtain a lithium bicarbonate solution which is subjected to ultrasonic crystallization to obtain a battery-grade lithium carbonate product.

[0016] Document CN118109687 describes a method for recovering nickel, cobalt, manganese and lithium from reduced black mass. The grinded, calcined material is soaked in water and filtered. The filtrate is treated with hydrogen peroxide, sodium carbonate and sodium hydroxide to adjust the pH to 11 , filtered and subsequently treated with sodium carbonate, evaporated and concentrated at 90° C to produce crude lithium carbonate.

[0017] US patent application US20240344174 focuses on the recovery of lithium from lithium iron phosphate black mass, roasting the black mass in a controlled environment to facilitate the extraction of lithium.

[0018] European patent application EP4372113A1 discloses a method for lithium recovery from recycled streams of lithium-ion batteries, including roasting a black mass in a partial oxygen environment, facilitating the extraction of lithium in water. This lithium leach solution is subsequently heated to recover the lithium as a precipitate.Summary of the invention

[0019] The present inventors found that the lithium recovery from black mass can be optimized by using a very specific sequence of process steps, in particular by introducing a lower temperature treatment step prior to the pyrolysis. Advantageously, the process of the present invention can be used on both lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxides (NMC) batteries, and even combinations thereof. Accordingly, the invention concerns a process for recycling lithium batteries, said process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;c. subjecting the dry shredded lithium batteries to a first treatment to remove volatile organics and to obtain a first temperature treated black mass, said first temperature has a temperature of at most 200°C;d. separating the copper and aluminium foils from the first temperature treated black mass to obtain a clean black mass;e. subjecting the clean black mass to a second temperature treatment to liberate Li from the cathode (CAM) and obtain a second temperature treated black mass, wherein the second temperature has a temperature of at least 500°C;f. leaching the second temperature treated black mass with CO2 and water to separate the lithium from a residue comprising graphite.

[0020] The inventors also found an alternative process, which also optimizes the recovery from lithium of black mass, said alternative process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;d. separating copper and aluminium foils from the dry shredded lithium batteries to obtain a black mass;c. subjecting the black mass to a first temperature treatment to remove electrolyte, volatile organics and PVDF to obtain a first temperature treated black mass, said first temperature treatment has a temperature of at most 480°C;e. subjecting the first temperature treated black mass to a second temperature treatment to liberate Li from the cathode active material (CAM) and obtain a second temperature treated black mass, said second temperature treatment has a temperature of at least 500°C;f. treating the second temperature treated black mass with CO2 and water to separate the lithium from a residue comprising graphite, the treatment involving either the reaction step:Li2CO3(s) + CO2(g) + H2O (I) 2 LiHCO3(aq);or the reaction steps:U2CO3 + H2O (I) ->• LiOH (aq) + LiHCO3(aq)Li2CO3(s) + 2 NaOH (aq) + H2O (I) ->• 2 LiOH (aq) + Na2CO3(aq)2 LiOH (aq) + CO2(g) ->• Li2CO3(s) + H2O (I).

[0021] Herein, steps c and d are performed in reverse order compared to the first described process.

[0022] Although, the inventors do not wish to be bound by theory, it is believed that both processes prevent the formation of LiAIO2, which ensures a higher yield of lithium during the extraction process.Brief description of the Figures

[0023] Figure 1 depicts the thermal stability of LiP4(C2C>4) and LiPFe.

[0024] Figure 2 depicts a schematic overview of a typical lithium battery.Detailed descriptionDefinitions

[0025] The verb “to comprise”, and its conjugations, as used in this description and in the claims is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded.

[0026] Reference to an element by the indefinite article “a” or “an” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there is one and only one of the elements. The indefinite article “a” or “an” thus usually means “at least one”.

[0027] Reference to certain metals, e.g. nickel and cobalt, is not limited to any oxidation state. For instance, a reference to cobalt may refer to Co(V), Co(IV), Co(lll), Co(ll), Co(l) and Co(l).

[0028] LFP battery is the abbreviation for lithium iron phosphate battery. A LFP battery typically comprises a cathode of lithium iron phosphate, i.e. LiFePC , and an anode comprising graphite.

[0029] NMC battery is the abbreviation for lithium nickel manganese cobalt oxides. A NMC battery typically comprises an anode comprising graphite and a cathode comprising mixed metal oxides of lithium, nickel, manganese and cobalt, typically of the formula LiNixMnyCoi-x-y02.

[0030] NMC may also be followed with a number, said number indicates the molar composition nickel, manganese and cobalt respectively. NMC111 or NMC333 thus refers to LiNio 33Mno 33C0033O2 and NM622 toLiNio eMno 2Mno 2O2. In case a single digit is not sufficient to describe the ratios between the metals, the 7” may be placed between the numbers. For instance, a NMC battery having a Ni:Co:Mn ratio of 90:5:5 can be depicted as NMC90 / 5 / 5 or as NMC9 / 0.5 / 0.5. In the context of the present application, NMC also include NMC100 which is known as lithium nickel dioxide (LNO) and NMC001 which is known as lithium cobalt oxide (LCO).

[0031] The term “metal” refers to element groups alkali metals, alkaline earth metals, transition metals, post-transition metals, lanthanides and actinides. It is not only limited to metals in their unoxidized state, but also includes metals as cations. E.g. both Li+and Li(s) are encompassed by the term metal.

[0032] The term “battery-grade”, as used in “battery grade lithium” refers to the quality, i.e. the level of impurities. Frequently, >99% purity is required. The exact specifications may very depending on the intended use and the specifications of the batteries, but this term is nevertheless well understood by a person skilled in the art.The process of the invention

[0033] The present invention concerns a process for recycling lithium batteries, said process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;c. subjecting the dry shredded lithium batteries to a first treatment to remove volatile organics and to obtain a first temperature treated black mass, said first temperature has a temperature of at most 200°C;d. separating the copper and aluminium foils from the first temperature treated black mass to obtain a clean black mass;e. subjecting the clean black mass to a second temperature treatment to liberate Li from the cathode (CAM) and obtain a second temperature of at least 500°C;f. leaching the second temperature treated black mass with CO2 and water to separate the lithium from a residue comprising graphite.

[0034] Alternatively, the process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;d. separating copper and aluminium foils from the dry shredded lithium batteries to obtain a black mass;c. subjecting the black mass to a first temperature treatment to remove electrolyte, volatile organics and PVDF to obtain a first temperature treated black mass, said first temperature treatment has a temperature of at most 480°C;e. subjecting the first temperature treated black mass to a second temperature treatment to liberate Li from the cathode active material (CAM) and obtain a second temperature treated black mass, said second temperature treatment has a temperature of at least 500°C;f. treating the second temperature treated black mass with CO2 and water to separate the lithium from a residue comprising graphite, the treatment involving either the reaction step:Li2CO3(s) + CO2(g) + H2O (I) 2 LiHCO3(aq);or the reaction steps:U2CO3 + H2O (I) ->• LiOH (aq) + LiHCO3(aq)Li2CO3(s) + 2 NaOH (aq) + H2O (I) ->• 2 LiOH (aq) + Na2CO3(aq)2 LiOH (aq) + CO2(g) ->• Li2CO3(s) + H2O (I).Step a: The lithium batteries

[0035] A typical battery comprises an anode, cathode, electrodes, electrolyte, separator, carrier, binders, casing, poles, wiring and sometimes a printed circuit board. All these components have a differentcomposition which provides a challenge to separate efficiently. An example of a Lithium battery has been depicted in Figure 2.

[0036] Typically, the lithium batteries are LFP batteries, NMC batteries or combinations thereof, herein LFP and NMC are the type of cathode that is used in the lithium battery. In a preferred embodiment, the lithium batteries are LFP batteries. In some embodiments, the cathode may be a lithium nickel cobalt aluminium oxide cathode, which is also known as a LNCA or a NCA cathode.

[0037] In another preferred embodiment, the lithium batteries are NMC batteries. More preferably, the NMC batteries are selected from NMC111 , NMC532, NMC622, NMC811 , NMC9 / 0.5 / 0.5.

[0038] The anode of a lithium battery typically comprises graphite. Wherein Li+is deposited on graphite as CeLi during charging, and Li+is released from the graphite during charging. Hence, the anode typically comprises lithium, wherein the quantity of lithium is dependent on the charge of the battery.

[0039] The electrodes of a lithium battery typically comprise a copper foil and an aluminium foil, wherein the copper foil is attached to the anode and the aluminium foil is attached to the cathode. Typically a binder may be used for connecting the foils with the anode and cathode. Herein, polyvinyl difluoride (PVDF) is preferably used to bond the cathode to the aluminium foil. Similarly, it is preferred that PVDF is used to bond the anode to the copper foil.

[0040] Lithium batteries typically comprise an electrolyte comprising LiPFe in an organic solvent. Alternatively, LiPF4(C2C>4) is used as lithium salt in the electrolyte. It is thus especially preferred that the lithium batteries of step a comprise LiPFe and / or LiPF4(C2C>4). Other preferred lithium salts that the electrolyte may comprise are LiCIO4, LiAsFe and LiCFeSOe. Typically the organic solvent is a non-aqueous solvent such as an alkyl carbonate. More preferably, organic solvents in the electrolyte include ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethyl acetate (EA), propylene carbonate (PC) and diethyl carbonate (DEC), and combinations thereof. The organic solvents may also refer to as volatile organics.

[0041] The separator separates the anode and cathode but allows for ion transport of Li+. Preferred separators comprise polyolefins, polyvinyl chloride, polymethylmethacrylate, siloxanes, polyvinylidene fluoride, polytriphenylamine and combinations thereof. More preferably, the separator comprises polyethylene or polypropylene.

[0042] Typical casing materials include plastic, steel and aluminium. In some embodiments, the battery is a pouch cell, herein the casing comprises of a thin aluminium laminated film wrapped around the battery cell, said film typically comprising polyamide, polyester-polyurethane or polypropylene.

[0043] The terminals or poles typically comprise nickel. More preferably, the terminals are an alloy of nickel, stainless steel and copper. The wiring is typically copper.

[0044] In an especially preferred embodiment, the lithium batteries are dismantled before step b. Dismantling typically involves separation of the outer casing, wires, jackets etc through physical means.

[0045] In an especially preferred embodiment, the lithium batteries are discharged prior to step a / b. Discharging is well known to the skilled person and includes chemical discharge methods such as immersing the batteries in a brine solution, simply discharging the battery by using the battery, connecting the battery to an external load, e.g. halogen bulb or resistor, to drain the battery. Discharging is beneficial as it can help to prevent short-circuiting, burning, explosions or spontaneous combustion. Preferably, the discharge method does not include an aqueous solution such as a brine solution. In other words, it is preferred that the discharge method is dry. Using a dry discharge method has the advantage that lesslithium is lost as the highly soluble LiPFe of the electrolyte will not dissolve in the aqueous discharge medium.

[0046] In another preferred embodiment, the lithium batteries are not discharged. Overcoming the hazards associated with the use of non-discharged batteries is known in the art, and can be used by using an inert atmosphere during the dry shredding and preferably also during the first temperature treatment.

[0047] Preferably, the lithium batteries are at least partly discharged, for partly discharged lithium batteries it is also preferred that dry shredding and more preferably also the first temperature treatment is under inert atmosphere.Step b: Dry shredding

[0048] Step b of the process of the present invention concerns dry shredding. Preferably dry shredding involves hammer mills or impact crushers, knife or cutting mills, jaw crushers, ball mills and combinations thereof.

[0049] In a preferred embodiment, the lithium batteries were not discharged and dry shredding occurs in an inert atmosphere. Inert atmospheres are known to the skilled person and include any inert gas such as N2, He, Ar and CO2, preferably the inert gas is N2.

[0050] Preferably step b also concerns the separation of plastics.Step c: The first temperature treatment

[0051] The first temperature treatment of step c removes the volatile organics and electrolyte salt, and may also be referred to as a low temperature treatment. These compounds are inherently present in a lithium battery. In the state of the art, volatile organics are typically concomitantly removed when the batteries are subjected to pyrolysis. The present inventors found that it is advantageous to remove the aforementioned compounds in a separate step prior to pyrolysis. As a mild temperature treatment effectively removes them while avoiding the formation of LiF and IJAIO2. LiF and IJAIO2 are insoluble which means that the leaching step f with CO2 does not effectively leach all available lithium if these salts are present. Hence, the prevention of the formation of these salts is highly beneficial for effectively recycling lithium.

[0052] In one embodiment, IJAIO2 and LiF formation is prevented by using a low temperature treatment of at most 200 °C. On the other hand, enough heat should be applied to evaporate the electrolyte and / or organics. Preferably, the temperature of the first treatment step is thus in the range of 75°C to 190 °C, more preferably 125°C to 180 °C, even more preferably 150 °C to 175 °C, most preferably 160 °C to 165 °C. Furthermore, the low temperature treatment avoids degradation of LiPFe and LiPF4(C2C>4) which is shown in Figure 1.

[0053] In another embodiment, LiAIC>2 and LiF formation is also prevented by using a low temperature treatment. Surprisingly, the inventors found that by removing the foils (step d) prior to the low temperature treatment, these effects can be achieved at a slightly higher temperature. In this embodiment, the temperature is at most 480 °C. Preferably, the temperature is in the range of 200 to 460 °C, more preferably in the range of 250 to 455 °C, most preferably in the range of 400 to 450°C.

[0054] Although LiPF6may undergo partial degradation at these temperatures, LiF formation remains minimal because the generated PFSevaporates and is removed from the material, thereby suppressing HF formation and preventing secondary LiF-forming reactions. Preferably, evaporation of PFSis accelerated by operating under reduced pressure. Although, the inventors do not wish to be bound by theory it isbelieved that the formation of LiF and IJAIO2 is prevented despite degradation of PVDF, as at this temperature in the absence of the Cu an Al foils, HF is formed instead.

[0055] Evaporation can also be promoted by lowering the pressure. Thus, in a preferred embodiment, the pressure in step c is in the range of 0 to 1 bar, preferably 0.01 to 0.9 bar, more preferably 0.1 to 0.8 bar, most preferably 0.3 to 0.6 bar. Evaporation is in particular useful for organics with a boiling point slightly higher than 200 °C.

[0056] In a preferred embodiment, the first temperature treatment is under an inert atmosphere, preferably the inert gas is selected from N2, He, Ar, CO2 and combinations thereof, more preferably the inert gas is N2.

[0057] Preferably, the first temperature treatment takes at least 30 minutes, more preferably 40 to 120 minutes, most preferably 45 to 80 minutes.Step d: Copper and aluminium foil removal

[0058] Removal of copper and aluminium foils before the high temperature treatment is highly advantageous as it avoids the formation of the insoluble salt LiAIC>2.

[0059] Removal of copper and aluminium foil is known to the skilled person and includes eddy current separation, gravity separation, sieving thermal treatment, electrical disintegration, mechanical separation, ultrasonic treatment, solvent delamination and combinations thereof.

[0060] In the embodiment of the present invention in which step c is prior to step d, the process has the advantage that the separation of the copper and aluminium foils is more facile, due to a very subtle degradation of PVDF and the plastics in the first temperature treatment, i.e. the plastics and PVDF are not chemically degraded or only marginally, but the bonding of the plastics and PVDF to aluminium / copper and the NMC / graphite has been weakened due to first temperature treatment.

[0061] This separation step preferably occurs at a temperature lower than 600 °C such that IJAIO2 formation is prevented, more preferably the separation step occurs at a temperature lower than 200 °C, most preferably at a temperature lower than 165 °C. Typically, no heat is supplied during the step d.

[0062] Preferably, step d also involves the separation of plastics from the black mass. Preferably, step d involves the separation of at least a part of the PVDF from the black mass. More preferably, step d concerns both the separation of plastics and the separation of at least part of the PVDF. Separation of PVDF or at least a part of the PVDF in step d is especially advantageous as this result in a lower level of PVDF in the clean black mass. Hence, pyrolysis of a clean black mass with reduced levels of PVDF in step e results in reduced LiF formation, which increases the yield of lithium leaching in step f.

[0063] Preferably step d is a combination of multiple separation techniques, more preferably step d is a combination of drum separation, cyclone separation, vibratory screen separation, vibratory separation and grinding, wherein each step may be individually occurred more than once.

[0064] The black mass obtained from step d is referred to as clean black mass, as this black mass has low levels of plastics, copper and aluminium.Step e: Pyrolysis

[0065] The second temperature treatment, or high temperature treatment, liberates Li from the cathode (CAM). In a preferred embodiment, this second temperature treatment step is pyrolysis. Pyrolysis is known to the skilled person, and involves heating under inert conditions.

[0066] The second temperature step is at least 500°C to liberate Li from the CAM. Typically 500°C to 1000°C, preferably the temperature is in the range of 550 °C to 900 °C, more preferably in the range of 580 °C to 800 °C, most preferably 600 to 750 °C. As aluminium foil has already been removed in the step d, the process avoids the formation of aluminium and copper oxides. This is highly advantageous as the lack of aluminium oxides also means that no LiAIC>2 will be formed, which means that the subsequent leaching step f has a higher yield of lithium. Similarly, the low levels of binder mean that less side reaction occur which results in a cleaner product and more efficient separation.

[0067] The second temperature treatment preferably takes 30 to 180 minutes, more preferably 40 to 120 minutes, most preferably 60 to 90 minutes.Step f: Leaching

[0068] In step f of the present invention, lithium is separated from a residue comprising graphite with water and CO2.

[0069] In a specially preferred embodiment, step f of the present invention involves the leaching of the high temperature treated black mass with CO2. CO2 promotes the formation of LiHCCh which is soluble in water, contrary to remaining metals that are present as stable alloys or stabile oxides, e.g. nickel, manganese and cobalt oxides that are hardly soluble in water or insoluble in water. Hence, leaching with CO2 enables selective removal of lithium. The chemical reaction of the leaching step is given below:Li2CO3(s) + CO2(g) + H2O (I) 2 LiHCO3(aq)

[0070] In a preferred embodiment, the black mass is milled before the leaching step. Milling has the advantage that it decreases the particle grain size, which means that the surface to volume ratio is increased and therefore results in improved leaching. Preferably, the milling results in a black mass having at least 90 wt.%, more preferably at least 95 wt.%, most preferably 99.5 to 100 wt.% of black mass with a particle grain size lower than 120 pm, more preferably 1 to 80 pm, most preferably 10 to 65 pm.

[0071] In a preferred embodiment, this step is performed under pressure, said pressure is preferably in the range of 1 to 50 bar, more preferably 1.5 to 4 bar, even more preferably 2 to 3 bar, most preferably 2.2 to 2.5 bar. The pressure can be controlled by controlling the temperature in the reactor, and the CO2 input.

[0072] In a preferred embodiment, the pressure relative to the atmospheric pressure is preferably < 1 barg, more preferably the pressure is in the range of 0.1 to 0.9 barg, even more preferably the pressure is in the range of 0.2 to 0.8 barg, most preferably the pressure is in the range of 0.4 to 0.7 barg.

[0073] Preferably, the temperature during leaching is 20 to 100°C, more preferably 30 to 90, even more preferably 40 to 80 °C, most preferably 45 to 60°C.

[0074] Water is necessary in this step in orderto produce the HCCh' ions from CO2. HCCh' is in equilibrium with carbonate and CO2. Therefore, it is preferred that the pH shifts the equilibrium in favour of HCCh' as LiHCCh has a higher solubility than L2CO3; similarly the equilibrium should not be in favour of CO2 or H2CO3. Thus, it is preferred that the pH is 6.35 to 10.33, preferably the pH is in the range of 7 to 9.5, more preferably the pH is in the range of 7.5 to 9.0, most preferably in the range of 8.2 to 9.0. Furthermore, at these pH ranges the solubility of nickel, cobalt and manganese is low, resulting in effective selective removal of lithium.

[0075] The amount of water should be in a sufficient quantity to dissolve most of the lithium, yet at the same time it is preferred to not use too much water for a more efficient overall process in terms of waste and energy need. Hence, it is preferred that the aqueous LiHCCh solution has a concentration of at least2 g / l of LiHCO3, preferably at least 10 g / L of LiHCO3, more preferably in the range of 15 to 60 g / L, even more preferably in the range of 20 to 58 g / L, even more preferably more preferably in the range of 30 to 57 g / L, even more preferably in the range of 45 to 58 g / L, most preferably aqueous solution is saturated with LiHCO3.

[0076] Preferably, the aqueous LiHCO3solution comprises at least 2 g / L of Li, more preferably 3 to 6 g / L of Li, even more preferably 4 to 5.8 g / L of Li, most preferably 4.5 to 5.44 g / L of Li.

[0077] Alternatively, the aqueous LiHCO3solution has a concentration of at least 2 g / L of LiHCO3, more preferably 10 g / L, even more preferably 20 g / L, even more preferably 30 g / L, even more preferably 40 g / L, even more preferably, 50 g / L, most preferably the LiHCO3solution is saturated with LiHCO3

[0078] Preferably, the total concentration of Ni, Co and Mn in the aqueous LiHCO3solution is at most 1 g / L, more preferably at most 100 mg / L, even more preferably at most 50 mg / L, even more preferably 0 to 10 mg / L, most preferably 1 ng / L to 1 mg / L.

[0079] After the leaching step an aqueous LiHCO3solution is obtained and a residue comprising graphite. If a NMC battery is used, the residue typically further comprises nickel, manganese and cobalt. In an especially preferred embodiment, the lithium batteries are NMC batteries and the process further comprises a step of refining nickel, manganese and / or cobalt from the residue of step f.

[0080] In an alternative embodiment, the high temperature black mass is leached with an aqueous solution having a pH in the range of 7 to 10, most preferably a diluted sodium hydroxide solution. Herein, lithium carbonate is converted into lithium hydroxide and lithium bicarbonate which are highly soluble in the aqueous solution, whereas the other remaining metals such as nickel, manganese and cobalt, are either present as alloys and / or oxides which are not highly soluble or insoluble in aqueous solutions. The obtained aqueous solution comprising lithium hydroxide is subsequently treated with carbon dioxide to re-precipitate the lithium as lithium carbonate. Accordingly, this leaching step can be represented by the following reactions:U2CO3 + H2O (I) ->• LiOH (aq) + LiHCO3(aq)Li2CO3(s) + 2 NaOH (aq) + H2O (I) ->• 2 LiOH (aq) + Na2CO3(aq)2 LiOH (aq) + CO2(g) ->• Li2CO3(s) + H2O (I)Step q: Flotation

[0081] In a preferred embodiment, the process of the invention further comprises step g, the separation of graphite from the residue by flotation. Flotation is known to the skilled person and is a separation technique that utilizes the degree of floatability of graphite as the hydrophobic graphite adheres to air bubbles and thus float to the surface of the liquid phase, while hydrophilic materials such as metal oxides remain in the liquid phase. Typically, flotation is enhanced by the addition of agents such as collectors, frothers and / or regulators.

[0082] Collectors include kerosene, diesel, liquid heavy oil, Escaid TM110, xanthates, amines and other hydrocarbon oils. Collectors are in particularly preferred for LFP batteries. If the residue in step g is derived from NMC batteries, it is preferred that no collector is used, as oils may interact with NMC as well.

[0083] A frother stabilizes the air bubbles and include compounds such as pine oil, isoamyl alcohol and methyl isobutyl carbinol (MIBC). MIBC is preferably used as frother. In a preferred embodiment, the liquid phase comprises 0.1 to 100 ppm of frother, more preferably 0.5 to 50 ppm of frother, most preferably 1 to 10 ppm of frother.

[0084] Regulators include pH regulars, dispersants, inhibitors and flocculants.

[0085] Step g thus results in a froth phase (graphite) and a liquid phase comprising the remaining metals of the black mass. Herein, the liquid phase has minimal impurities.

[0086] Preferably 50 to 500 g of residue is used per litre of liquid phase, more preferably the 100 to 400 g / L, most preferably 150 to 300 g / L.

[0087] Typically flotation is performed in a flotation cell. Herein, it is preferred that the impeller speed is 100 to 2000 rpm, more preferably 500 to 1500 rpm, most preferably 800 to 1100 rpm. Air is preferably fed to the flotation cell at a flow of 0.1 to 10 L / min, more preferably 0.5 to 5 L / min, most preferably 1 to 3 L / min.

[0088] The liquid phase is typically an aqueous liquid, more preferably the aqueous liquid is water, most preferably the liquid phase is deionized water or ultra-high purity water.

[0089] Typically a base is present, which helps to improve the segregation between phases. Preferably, the pH is in the range of 6.5 to 10, more preferably the pH is in the range of 7 to 9.5, most preferably the pH is in the range of 8 to 9.

[0090] Typically the froth is collected by filtration and subsequently dried. Preferably, drying occurs at an elevated temperature, but not so high that the graphite combusts. Hence, preferred temperatures are in the range of 30 to 500 °C, more preferably 35 to 100 °C, most preferably 40 to 50 °C.

[0091] Drying may also be accelerated by reduced pressure. Preferably, the pressure is 0 to 1 bar, preferably 0.01 to 0.9 bar, more preferably 0.1 to 0.8 bar, most preferably 0.3 to 0.6 bar.ExamplesExample 1

[0092] The present invention is exemplified by the following Example.

[0093] Black mass can be obtained from dismantled and discharged end-of-life NMC batteries. During the pretreatment process to produce this black mass, volatile organic compounds were removed during a heat treatment at 150°C. Crushing and separating separates black mass from copper and aluminium foils.

[0094] The clean black mass can be subjected to a pyrolysis step at 600°C with a heating rate of 15°C / min.

[0095] After pyrolysis, 500 g of black mass with the following composition can be taken for the CO2 / water leaching process. The obtained black mass can be milled to reduce the particle grain size less than 63pm to enhance the lithium recovery yield.

[0096] The table below depicts the weight percentages of the obtained black mass composition.

[0097] Herein, C represents the graphite content.

[0098] The low temperature heat treatment (150°C) allows for a better separation of cathode materials from foils and avoids generation of LiF. Lithium compounds in this black mass dissolve as LiHCCh using CO2 and water.

[0099] Leaching can be performed at 50°C for 180 min with a solid : liq u id weight ratio 2:10; the equilibrium pH reached during CO2 addition is 8.27.

[0100] The lithium-depleted black mass can be separated by filtration through a qualitative filter paper, washed and dried. The remaining LiHCCh solution can be collected for analysis and contained 25.2 g of Li, which represents a 95% leaching efficiency.

[0101] The LiHCO3 containing solution can be heated to 95°C where thermal decomposition of LiCCh into IJ2CO3 occurs; solid IJ2CO3 is separated on a qualitative filter paper. The filtrate obtained from this thermal decomposition step can be recycled to the CO2 leaching step to recover lithium.

[0102] 429.5 g of lithium-depleted black mass can be recovered, containing 2,5 g of Li containing compounds; this residue is forwarded to the graphite recovery setup.

[0103] Organic compounds such as the binder and electrolyte residue present in spent lithium ion batteries can form hydrophobic coatings on the lithium metal oxide particles, thereby reducing their hydrophobic differences versus graphite. The different pretreatment steps in the claimed process effectively remove these compounds, resulting in a complete liberation of the particles and rendering the flotation more effective.

[0104] Methyl isobutyl carbinol (MIBC) can be used as the frother as it absorbs on the surfaces of the graphite particles, increasing their hydrophobicity and promoting their attachment to air bubbles.

[0105] Oily collectors can interact with both NMC and graphite particles; therefore, no collector can be used. The flotation experiments were performed using a 1 -litre flotation cell; 40 g of lithium-depleted black mass can be mixed with 1 -litre of ultra-high purity water. The pulp can be mixed in the flotation cell with an impeller speed of 1000 rpm for 3 min and MIBC frother can be added to the flotation cell at a concentration of 8 ppm. After mixing for another 2 min, the impeller speed can be reduced to 850 rpm and air can be fed at a flow of 2 l / min, to initiate flotation, and froth can be scooped and collected for a total of 25 min. During the flotation experiment, the atmosphere can be monitored with a portable HF detector. The absence of HF peaks would suggest that the majority of the electrolyte can be effectively removed during the pretreatment process.

[0106] The collected froth can be filtered and dried for 48h in a convection oven at 40°C; graphite recovery yield can be 80% from this experiment.Example 2

[0107] End-of-life lithium-ion battery modules comprising NMC-type cathode active material were mechanically treated to obtain a black mass fraction. The mechanical treatment comprised dismantling, crushing, and physical separation steps configured to separate metallic fractions from active materials.

[0108] The table below depicts the weight percentages of the input feed at module level:

[0109] During the mechanical treatment step, aluminum and copper were selectively recovered to metallic fractions with efficiencies of 96% and 96%, respectively. Iron-containing components were recovered at 98% efficiency, yielding to a clean black mass. The clean black mass was subjected to a temperature thermal treatment at 450 °C followed by 600°C under inert atmosphere. This treatment removes residual organic compounds and promotes transformation of lithium species into lithium carbonate. The pyrolyzed black mass has the following composition:

[0110] After thermal treatment, 500 g of the black mass can be milled to a particle size below 63 pm to enhance lithium conversion kinetics.

[0111] The thermally treated black mass can be subjected to alkaline leaching in an aqueous medium at a pH between 7 and 10, preferably using a diluted sodium hydroxide solution. Leaching can be performed at 50°C for 180 minutes at a solid-to-liquid weight ratio of 5:10.

[0112] Under these alkaline conditions, lithium carbonate present in the black mass can be converted into soluble lithium hydroxide species, while nickel, cobalt, and manganese remained predominantly in the solid phase as stable oxides and / or metallic alloys that are sparingly soluble in alkaline media.

[0113] After completion of the leaching step, the slurry can be filtered to separate 423 g of lithium-depleted black mass and a solution containing 14 g / L Li at pH 8.5. The residue can be washed and dried for further downstream processing.

[0114] Lithium recovery into solution exceeded 90% of the lithium present in the thermally treated black mass.

[0115] Carbon dioxide gas can subsequently be introduced into the lithium hydroxide-containing solution to precipitate lithium carbonate selectively according to the reaction:2 LiOH (aq) + CO2(g) Li2CO3(s) + H2O

[0116] 64 g of Li2COs can be recovered by filtration and drying. The remaining sodium bicarbonate-containing solution can be recycled to the leaching step.List of embodiments1. A process for recycling lithium batteries, said process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;c. subjecting the dry shredded lithium batteries to a first temperature treatment to remove electrolyte and / or volatile organics and to obtain a first temperature treated black mass, said first temperature treatment has a temperature of at most 200°C;d. separating copper and aluminium foils from the first temperature treated black mass to obtain a clean black mass;e. subjecting the clean black mass to a second temperature treatment to liberate Li from the cathode active material (CAM) and obtain a second temperature treated black mass, said second temperature treatment has a temperature of at least 500°C;f. leaching the second temperature treated black mass with CO2 and water to obtain an aqueous LiHCCh solution and a residue comprising graphite.2. The process according to claim 1 , wherein the one or more lithium batteries were discharged prior to the dry shredding.3. The process according to claim 1 or 2, wherein the process further comprises:g. separating the graphite from the residue by flotation.4. The process according to any one of the preceding claims, wherein the first temperature treatment of step c is in the range of 75°C to 190 °C, preferably 125°C to 180 °C, even more preferably 150 °C to 175 °C.5. The process according to claim 4, wherein in the first temperature treatment of step c is in the range of 160 to 165°C.6. The process according to any one of the preceding claims, wherein the pressure during step c is in the range of 0 to 1 bar, preferably 0.01 to 0.9 bar, more preferably 0.1 to 0.8 bar, most preferably 0.3 to 0.6 bar.7. The process according to any one of the preceding claims, wherein the copper and aluminium foils are separated by eddy current separation, gravity separation, sieving, thermal treatment, electrical disintegration, mechanical separation, ultrasonic treatment, solvent delamination and combinations thereof, provided that the temperature does not exceed 500°C in this step.8. The process according to any one of the preceding claims, wherein the second temperature treatment of step e is in the range of 510 °C to 1000°C, preferably in the range of 550 °C to 900 °C, more preferably in the range of 600 °C to 800 °C, most preferably 650 to 750 °C.9. The process according to any one of the preceding claims, wherein the aqueous LiHCCh solution has a concentration of at least 2 g / L of LiHCCh, more preferably 10 g / L, even more preferably 20 g / L, even more preferably 30 g / L, even more preferably 40 g / L, even more preferably, 50 g / L, most preferably the LiHCCh solution is saturated with LiHCCh10. The process according to any one of the preceding claims, wherein the total concentration of Ni, Co and Mn in the aqueous LiHCCh solution of step f is at most 1 g / L, preferably at most 100 mg / L more preferably at most 0 to 50 mg / L, even more preferably 0 to 10 mg / L, most preferably 1 ng / L to 1 mg / L.11. The process according to any one of the preceding claims, wherein the aqueous LiHCCh solution has a pH in the range of 6.35 to 10.33, preferably the pH is in the range of 7 to 9.5, more preferably the pH is in the range of 8.2 to 9.0.12. The process according to any one of the preceding claims, wherein the one or more lithium batteries are selected from lithium nickel manganese cobalt oxides (NMC) batteries, lithium iron phosphate (LFP) batteries, and combinations thereof.13. The process according to claim 12, wherein the lithium batteries are NMC batteries and the process further comprises a step of refining nickel, manganese and / or cobalt from the residue of step f.14. The process according to claim 12, wherein the lithium batteries are LFP batteries.15. The process according to any one of the preceding claims, wherein step d also concerns the separation of plastics.

Claims

CLAIMS1. A process for recycling lithium batteries, said process comprising:a. providing one or more lithium batteries;b. dry shredding the one or more lithium batteries;d. separating copper and aluminium foils from the dry shredded lithium batteries to obtain a black mass;c. subjecting the black mass to a first temperature treatment to remove electrolyte, volatile organics and PVDF to obtain a first temperature treated black mass, said first temperature treatment has a temperature of at most 480°C;e. subjecting the first temperature treated black mass to a second temperature treatment to liberate Li from the cathode active material (CAM) and obtain a second temperature treated black mass, said second temperature treatment has a temperature of at least 500°C;f. treating the second temperature treated black mass with CO2 and water to separate the lithium from a residue comprising graphite, the treatment involving either the reaction step:Li2CO3(s) + CO2(g) + H2O (I) 2 LiHCO3(aq);or the reaction stepsU2CO3 + H2O (I) ->• LiOH (aq) + LiHCO3(aq)Li2CO3(s) + 2 NaOH (aq) + H2O (I) ->• 2 LiOH (aq) + Na2CO3(aq)2 LiOH (aq) + CO2(g) ->• Li2CO3(s) + H2O (I).

2. The process according to claim 1 , wherein the one or more lithium batteries were discharged prior to the dry shredding.

3. The process according to claim 1 or 2, wherein the process further comprises:g. separating the graphite from the residue by flotation.

4. The process according to any one of the preceding claims, wherein the first temperature treatment of step c is in the range of 200°C to 460 °C, preferably 250°C to 455 °C.

5. The process according to claim 4, wherein in the first temperature treatment of step c is in the range of 400 to 450°C.

6. The process according to any one of the preceding claims, wherein the pressure in step c is in the range of 0 to 1 bar, preferably 0.01 to 0.9 bar, more preferably 0.1 to 0.8 bar, most preferably 0.3 to 0.6 bar.

7. The process according to any one of the preceding claims, wherein the copper and aluminium foils are separated by eddy current separation, gravity separation, sieving, thermal treatment, electrical disintegration, mechanical separation, ultrasonic treatment, solvent delamination and combinations thereof, provided that the temperature does not exceed 500°C in this step.

8. The process according to any one of the preceding claims, wherein the second temperature treatment of step e is in the range of 510 °C to 1000°C, preferably in the range of 550 °C to 900 °C, more preferably in the range of 580 °C to 800 °C, most preferably 600 to 750 °C.

9. The process according to any one of the preceding claims, wherein the aqueous LiHCCh solution has a concentration of at least 2 g / L of LiHCCh, more preferably 10 g / L, even more preferably 15 g / L, even more preferably 20 g / L, even more preferably 30 g / L, even more preferably 40 g / L, even more preferably 50 g / L, most preferably the LiHCCh solution is saturated with LiHCCh10. The process according to any one of the preceding claims, wherein the total concentration of Ni, Co and Mn in the aqueous LiHCCh solution of step f is at most 1 g / L, preferably at most 100 mg / L more preferably in the range of 0 to 50 mg / L, even more preferably in the range of 0 to 10 mg / L, most preferably in the range of 1 ng / L to 1 mg / L.

11. The process according to any one of the preceding claims, wherein the aqueous LiHCCh solution has a pH in the range of 6.35 to 10.33, preferably the pH is in the range of 7 to 9.5, more preferably the pH is in the range of 7.5 to 9.0.

12. The process according to any one of the preceding claims, wherein the one or more lithium batteries are selected from lithium nickel manganese cobalt oxides (NMC) batteries, lithium iron phosphate (LFP) batteries, and combinations thereof.

13. The process according to claim 12, wherein the lithium batteries are NMC batteries and the process further comprises a step of refining nickel, manganese and / or cobalt from the residue of step f.

14. The process according to claim 12, wherein the lithium batteries are LFP batteries.

15. The process according to any one of the preceding claims, wherein steps b and d also concern the separation of plastics.

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