LFP battery recycling equipment and method

Abstract

The present disclosure relates to an apparatus for recycling old batteries, in particular lithium iron phosphate (LFP) batteries, and to a method for recovering valuable materials from old batteries.

Description

Technical Field

[0001] The present disclosure relates to an apparatus for recycling used batteries, particularly lithium iron phosphate (LFP) batteries, and to a method for recovering valuable materials from used batteries. Background Art

[0002] Lithium-ion battery materials are a complex mixture of various elements and compounds. For example, lithium iron phosphate battery materials contain valuable metals such as lithium, aluminum, copper, and / or others. It may be desirable to recover various elements and compounds from lithium iron phosphate battery materials. For example, it may be advantageous to recover lithium and / or copper.

[0003] Lithium iron phosphate battery (LiFePO 4 4) or LFP battery (lithium iron phosphate) is a lithium-ion battery that uses lithium iron phosphate (LiFePO 4 4) as the cathode material and a graphite carbon electrode with a metal backing as the anode. Due to its low cost, high safety, low toxicity, long cycle life, and other factors, LFP batteries are playing many roles in vehicle use, utility-scale stationary applications, and backup power supplies. Therefore, there is a need for devices and methods for recycling used LFP batteries.

[0004] CN 112 768 800 A discloses a method for recycling lithium iron phosphate cathode materials. The recycling method includes dissolving the lithium iron phosphate cathode materials in an acid solution and adding an oxidant to oxidize the undissolved copper in the recovered materials to obtain filtrate I; adding reduced iron powder to the filtrate I to obtain filtrate II; adding lithium carbonate and / or lithium hydrogencarbonate to the filtrate II to completely precipitate aluminum ions to obtain filtrate III; adding a ferric salt or phosphoric acid to the filtrate III to adjust the molar ratio of iron to phosphorus in the filtrate III such that the molar ratio of iron to phosphorus in the filtrate III is (0.9 - 1.2):1, and simultaneously adding an oxidant and an acid solution to oxidize the ferrous salt in the filtrate III to ferric iron without producing ferric phosphate precipitate; and heating the reaction liquid obtained in step 4 to 60°C - 100°C and adding lithium carbonate and / or lithium hydrogencarbonate to completely precipitate ferric phosphate to obtain ferric phosphate solid and filtrate 4; wherein the fourth filtrate is used to prepare lithium carbonate, and the prepared lithium carbonate is used in the third step or the fifth step.

[0005] CN 108 110 357A discloses a method for recovering valuable metals from waste lithium iron phosphate battery cathode materials. The method specifically includes the following steps: (1) completely roasting and oxidizing the disassembled, cracked, and ground lithium iron phosphate battery cathode materials such that the Fe and Li metal elements in the battery cathode materials are generated into Fe 2 2O3 , FePO 4 and Li 3 PO 4 ; (2) Immerse the calcined material that has been completely calcined and oxidized in step (1) in a dilute acid solution, so that Li 3 PO 4 dissolves completely and is filtered to separate Li 3 PO 4 from Fe 2 O 3 and FePO 4 in the calcined material; (3) Take the filtrate obtained in step (3) and adjust the filtrate to be alkaline, so that Li 3 PO 4 is directly separated into a precipitate.

[0006] CN 114 044 503 A discloses a method for the separation, impurity removal and regeneration of lithium iron phosphate waste electrodes, which includes the following steps: grinding, crushing and screening the lithium iron phosphate waste electrodes to obtain lithium iron phosphate waste powder with an aluminum content of less than 0.2% by mass and aluminum particles, mixing the obtained lithium iron phosphate waste powder with zinc oxide (preferably activated zinc oxide), performing negative pressure calcination at a temperature of 650°C - 675°C to remove PVDF and F, demagnetizing and decarbonizing to obtain a mixture of iron(III) oxide and lithium iron(III) phosphate with a relatively low content of Al and F, and using the mixture of iron(III) oxide and lithium iron(III) phosphate as a raw material to obtain lithium iron phosphate.

[0007] CN 107 785 571 A discloses a method for recycling and reusing the cathode material of lithium iron phosphate batteries. The method includes the following steps: 1) heating the waste lithium iron phosphate in an air atmosphere at 500°C to 800°C to completely oxidize the material; 2) adding a carbon source and a dispersion medium to the material obtained in step 1, performing ball milling, completely mixing, and then drying the obtained mixture in a drying oven; 3) keeping the mixture obtained in step 2 at a certain temperature for 6 to 8 hours.

[0008] CN 112 661 130 A discloses a method for recycling the cathode of lithium iron phosphate batteries. The method includes the following steps: crushing the cathode of the lithium iron phosphate battery to obtain cathode fragments with a size of 3 - 6 cm, roasting the cathode fragments in a rotary kiln in an air atmosphere, where the rotary kiln includes a preheating section and a roasting section, the temperature of the roasting section is 400°C - 650°C, and the temperature difference between roasting and preheating is 200°C - 300°C; and finally screening to obtain active cathode powder.

[0009] CN 111 924 817 A discloses a method for comprehensively utilizing waste lithium iron phosphate cathode materials. The method includes the following steps: leaching the waste lithium iron phosphate cathode materials with an acid solution, adjusting the iron-phosphorus ratio of the leachate and adjusting the pH value to strong acidity, converting ferrous ions into ferric ions through an oxidation reaction to form iron phosphate precipitates, and performing liquid-solid separation to obtain hydrated iron phosphate and a lithium-containing solution; removing heavy metal ions from the lithium-containing solution by a precipitation method, and performing liquid-solid separation to obtain heavy metal precipitation residues and a purified lithium-containing solution; and adding a lithium ion precipitant to the purified lithium-containing solution, adjusting the pH value to weak acidity or alkalinity, performing a lithium ion precipitation reaction, and performing liquid-solid separation to obtain a lithium salt product.

[0010] CN 109 852 807 A discloses a method for oxidizing waste lithium ion batteries. The method includes adding waste lithium ion battery powder to an acidic aqueous solution to obtain a mixed slurry; inputting an oxidation gas into the mixed slurry with an aeration device and performing oxidative leaching; after the reaction is completed, adjusting the pH of the reaction slurry with an acid adjustment reagent to remove less valuable metal ions, and then performing solid-liquid separation to obtain a lithium-rich purified liquid and reaction tailings; and then performing lithium precipitation and solid-liquid separation on the purified liquid to obtain a lithium carbonate product or a lithium phosphate product.

[0011] CN 109 921 087 A discloses a method for comprehensively treating waste lithium iron phosphate batteries. The comprehensive treatment method includes: manual disassembly; drying and pyrolysis; crushing and separation; heat treatment, acid leaching; pressure filtration and washing; conversion; alkalization and impurity removal; and preparation of magnesium chloride.

[0012] CN 111 187 913 A discloses a method for selectively recovering lithium and copper from waste lithium iron phosphate batteries. The method includes mixing waste lithium iron phosphate batteries with inorganic acid and oxygen to react at 96°C - 150°C, and then performing solid-liquid separation to obtain a leachate and iron phosphate leaching residues, mixing the leachate with a separating agent to separate copper in the leachate, and then adding an alkaline substance to adjust the pH to remove impurity iron and aluminum to obtain a purified liquid; and precipitating the purified liquid and a sodium salt to obtain a lithium product.

[0013] KIM, Seoa et al.: "A comprehensive review on the pretreatment process in lithium-ion battery recycling", Journal of cleaner production, Vol. 294 (2021) 126329 provides an investigation of the pretreatment processes used in the recycling of Li-ion batteries. These processes include discharging, disassembly, shredding, sorting, separation, dissolution, and heat treatment.

[0014] TANAKA, Futoshi et al.: "Dehydrofluorination behavior of poly(vinylidene fluoride) during thermal treatment using calcium carbonate", Thermochimica Acta, Vol. 702 (2021) 178977 studied the HF emission behavior of poly(vinylidene fluoride) used as a binder in Li-ion batteries during heat treatment. Calcium carbonate was added to suppress the emission of HF.

[0015] The purpose of the present disclosure is to provide an improved recycling device for used LFP batteries and an improved recycling method for used LFP batteries. Summary of the Invention

[0016] There is provided a device for recycling lithium iron phosphate (LFP) battery materials, such as used LFP batteries, the device including a shredding device for shredding the LFP battery materials in a shredding space. The device includes a heat treatment device arranged downstream of the shredding device to dry and heat the shredded LFP battery materials. The device includes an intermediate storage device arranged between the shredding device and the heat treatment device. The device includes an oxidation device for oxidizing the heat-treated shredded LFP battery materials. In some embodiments, the device further includes a reactor for recovering valuable materials from the oxidized LFP battery materials.

[0017] Also provided is a method for recycling lithium iron phosphate battery materials (such as used LFP batteries). The method includes crushing the LFP battery materials, drying the crushed LFP battery materials and heating the crushed LFP battery materials at a temperature in the range of 250°C to 500°C, and subsequently oxidatively roasting the LFP battery materials at a temperature in the range of 500°C to 700°C. In some embodiments of the method, the obtained oxidized LFP battery materials are then leached with sulfuric acid, and valuable materials are recovered from the obtained solution.

[0018] Detailed description

[0019] An apparatus for recycling LFP battery materials (such as used LFP batteries) is provided. The apparatus includes a crushing device for crushing the LFP battery materials. The apparatus includes a heat treatment device disposed downstream of the crushing device to dry the crushed LFP battery materials and subject them to heat treatment in an inert or reducing atmosphere. The apparatus includes an oxidation device disposed downstream of the heat treatment device to oxidize the crushed and heat-treated LFP battery materials at an elevated temperature in an oxidizing atmosphere.

[0020] In some embodiments, the apparatus provides a first crushing of the used LFP battery materials and a second crushing of the LFP battery materials. The apparatus includes a first crushing device for crushing the LFP battery materials to a first degree of crushing in a first crushing space. The apparatus includes a heat treatment device disposed downstream of the first crushing device to dry the crushed LFP battery materials and subject them to heat treatment. The apparatus includes a second crushing device disposed downstream of the first crushing device and configured to further crush the heat-treated crushed LFP battery materials to a second degree of crushing in a second crushing space, the second degree of crushing being greater than the first degree of crushing. In some embodiments, the apparatus further includes at least one separation device to separate particles of the crushed LFP battery materials having different particle sizes or particle size ranges from each other, i.e., to separate LFP battery material particles having different particle sizes or particle size ranges into two or more fractions having correspondingly two or more different particle size ranges, for example, to separate LFP battery material particles of a small particle size fraction from LFP battery material particles of a large particle size fraction. Preferably, the LFP battery material particles are separated by screening.

[0021] In some embodiments, the second comminution device is arranged downstream of the heat treatment device to further comminute the heat-treated comminuted LFP battery material to a second degree of comminution. The second degree of comminution is greater than the first degree of comminution provided by the first comminution device. In some embodiments, a particle size of less than 20 mm is achieved in the first comminution device, and a particle size in the range of 0.5 - 3 mm is achieved in the second comminution device. In the context of the present disclosure, the particle size refers to the maximum particle size of all particles, i.e., all particles will pass through a sieve having a sieve aperture size corresponding to the respective particle size.

[0022] It should be noted that the cathode active material (CAM) of the LFP battery detached from the current collector foil disintegrates as a black substance into particles <250 μm. However, the disintegration of the cathode active material is not actually comminution but depolymerization. In the second comminution device, the comminuted and heat-treated LFP battery material fed to the second comminution device is subjected to mechanical pulping by comminution and then granulation, such that a second black substance fraction having particles with a size range of <250 μm is obtained, and the foil is present as granulated particles having a size of 1 - 5 mm, preferably 0.5 - 3 mm.

[0023] In some embodiments, some or all components of the device that are subject to a possible explosion (such as the first and / or second comminution devices, the heat treatment device, the intermediate storage device, and / or the separation device) are designed to be explosion-proof. In some embodiments, at least the second comminution device is designed to be explosion-proof.

[0024] To reduce the risk of spontaneous combustion, in some embodiments, an inert gas is supplied to at least some of the first comminution device, the intermediate storage device, the heat treatment device, the second comminution device, and the at least one separation device. The inert gas is a gas that at least hinders (if not even prevents) the spontaneous combustion of the comminuted battery during an electrochemical reaction. For example, nitrogen and / or carbon dioxide gas can be used as the inert gas. The inert gas reduces the oxygen concentration sufficiently. Thus, explosion protection can be achieved.

[0025] Regarding the mechanical design of the components of the device that are affected by a possible explosion, some embodiments provide corresponding components with a larger wall thickness and / or thicker bolts and nuts that prevent the walls of the corresponding components from rupturing, such that they can withstand greater pressure in the case of a dust explosion hazard, for example up to 10 bar above atmospheric pressure. Thus, these corresponding components are designed to be shock pressure resistant. Depending on the corresponding dimensions of the corresponding components, their walls and the tools provided for their cohesion (such as bolts, nuts, etc.) are selected to be suitably stable in order to withstand the pressure occurring in the event of a possible explosion in a calculable or evaluable manner. In the case where the shock pressure resistant components are connected to non-shock pressure resistant components via valves (especially rotary valves) / feeders, these valves are also designed to be shock pressure resistant. Thereby, the entire device area including the components affected by a possible explosion can be designed to be shock pressure resistant and still be connected to the remaining device components by means of these shock pressure resistant valves. Such an entire device area can be designed for a shock pressure above atmospheric pressure up to 10 bar in the case of a dust explosion hazard.

[0026] In some embodiments, at least the second comminution device and its inlets and outlets (including the corresponding valves arranged at these inlets and outlets) are designed to be shock pressure resistant.

[0027] In some embodiments, when a rotor impact mill is used as the second comminution device, the peripheral speed or tip speed of the mill is controlled and adjusted in a suitable manner, for example in the range of 20 - 120 m / s (20 m / s - 120 m / s), preferably 30 - 80 m / s, and even more preferably 40 - 60 m / s. However, it should be noted that the power impact depends on the construction size and peripheral speed of the rotor impact mill as well as the material fed into the mill.

[0028] In still further embodiments, shut-off valves, especially quick-closing valves, are provided in some or each exhaust duct / vent line of the device. Alternatively or additionally, the length of some or all of the exhaust duct lines is selected in such a way that the pressure can be released along the length of the corresponding exhaust duct line. It should be noted that at least some of the first comminution device, the heat treatment device, the second comminution device, and the pyrolysis device include at least one exhaust duct line. Pressure measuring tools can be provided to detect the pressure present in the device, especially in the corresponding components of the device affected by a possible explosion and / or the corresponding exhaust ducts, and to control the corresponding one or more quick-closing valves / dampers.

[0029] The device includes an intermediate storage device arranged between the (first) comminution device and the heat treatment device. The volume of the intermediate storage space of the intermediate storage device is at least five times, preferably at least ten times, the volume of the comminution space of the comminution device. The intermediate storage device further includes a stirring tool configured to keep the comminuted LFP battery material received in the intermediate storage space in motion. The intermediate storage device performs multiple functions in the device according to the present disclosure.

[0030] First, the intermediate storage allows the electrochemical reactions occurring in the comminuted LFP battery material to weaken to such an extent that they do not cause problems when the comminuted LFP battery material is supplied to the heat treatment device.

[0031] Furthermore, the intermediate storage device serves as a temporary reservoir for the comminuted LFP battery material. In this way, the device according to the present disclosure can be operated in a batch mode, such that in each batch only a small amount of LFP battery material (e.g., old LFP batteries) needs to be supplied to the comminution device, while a larger amount of comminuted LFP battery material can be supplied to the heat treatment device in one go. Since the amount of material to be comminuted in one step is small, the risk of spontaneous combustion can be practically excluded. This is particularly advantageous in the device according to the present disclosure when the old LFP batteries supplied to the comminution device have not been pre-discharged or at least not fully pre-discharged, and the residual charge driving the electrochemical reactions of the LFP batteries is unknown.

[0032] And finally, the freshly comminuted LFP battery material entering the intermediate storage space from the comminution device is mixed by the stirring tool with the comminuted LFP battery material previously introduced into the intermediate storage space (in which the electrochemical reactions have at least partially weakened). This helps to avoid the formation of local volumes with inadmissible high temperatures and an increased risk of spontaneous combustion.

[0033] All these measures ensure that in the device according to the present disclosure, essentially unprepared old LFP batteries, in particular old LFP batteries that have not been or at least not fully pre-discharged and disassembled, can be recycled in a substantially automated and thus cost-effective process.

[0034] In an exemplary device, 1 ton of LFP battery material can be recycled per hour. LFP battery material such as old LFP batteries is supplied to the comminution device in the form of ten 100 kg batches and is temporarily stored in the intermediate storage device before being transferred to the heat treatment device. In one embodiment, the volume of the comminution space of the comminution device is approximately 0.5 m 3 and / or the volume of the intermediate storage space of the intermediate storage device is approximately 6.0 m 3 and / or the volume of the heat treatment space of the heat treatment device is approximately 3.0 m 3It must be considered that the comminuted LFP battery material is compacted by a conveying device (such as a pipe screw conveyor) that conveys the material from an intermediate storage device to a heat treatment device.

[0035] In order to prevent environmentally incompatible or even dangerous gases from escaping from the LFP battery recycling equipment, in another embodiment of the equipment, it is proposed that the comminution space and / or the intermediate storage space and / or the heat treatment space are airtight.

[0036] In another embodiment, the transfer device for transferring the comminuted LFP battery material from the comminution device to the intermediate storage device and / or the transfer device for transferring the comminuted LFP battery material from the intermediate storage device to the heat treatment device are airtight and are connected to the adjacent devices in an airtight manner.

[0037] In another embodiment, an exhaust gas treatment device is provided, which is connected to the comminution space and / or the intermediate storage space and / or the heat treatment space via a gas supply pipeline and is configured to treat the gases formed in the comminution space and / or in the intermediate storage space and / or in the heat treatment space. Those skilled in the art are familiar with the components that the exhaust gas treatment device may or should include depending on the gas components generated. For this reason, a detailed discussion of the design and function of the exhaust gas treatment device can be omitted at this point.

[0038] In order to prevent oversized fragments of the comminuted LFP battery material from leaving the comminution device in the direction of the intermediate storage device, in another embodiment of the equipment, a sieve unit, such as a perforated sieve, is arranged at the outlet of the comminution device. In one embodiment, the openings of the sieve unit have a diameter of 20 mm. For example, a universal shredder of type NGU 0513 sold by BHS Sonthofen GmbH of Germany can be used as the comminution device.

[0039] The heat treatment device is configured to receive the comminuted LFP battery material and subject it to heat treatment in a heat treatment space provided within the heat treatment device. In some embodiments, the heat treatment device includes a supply pipeline for supplying an inert gas to the heat treatment space of the heat treatment device. In some embodiments of the equipment, the heat treatment device includes an oven, such as an electric oven.

[0040] In some embodiments of the equipment, the heat treatment device includes a rotary kiln. A rotary kiln is a cylindrical container that is slightly inclined with respect to the horizontal plane and slowly rotates about its longitudinal axis. The process raw material is fed into the upper end of the cylinder. As the kiln rotates, the material gradually moves downward towards the lower end and may undergo a certain amount of agitation and mixing.

[0041] In some embodiments of the device, the kiln has a length in the range of 12 to 18 m. In some embodiments of the device, the kiln has a length in the range of 15 to 17 m. The kiln length refers to the length of the heating zone of the kiln. Additional elements will make the entire kiln slightly longer. In some embodiments of the device, the inner diameter of the cylindrical tube is in the range of 1.5 to 2.1 m, such as 1.7 to 1.9 m.

[0042] In some embodiments of the device, the rotary kiln is characterized by external heating elements that use electricity. In some embodiments, the kiln includes a number of heating zones. In some embodiments, thermoelectric elements are provided in each heating zone for measuring the temperature in the corresponding zone. In one embodiment, each heating zone has a length in the range of 0.5 m to 6 m, such as 1 m to 4 m, such as 1.5 to 3 m. In some embodiments, the heating zones of the kiln near the inlet are shorter than those near the outlet.

[0043] In some embodiments of the device, the kiln is connected at the lower end with a material discharge hood and a conduit for the exhaust gas, and is characterized by being hermetically sealed at both ends of the kiln. Mounting equipment is used to eliminate hydrocarbons from the exhaust gas stream of the kiln before transferring the exhaust to the atmosphere.

[0044] The oxidation device is arranged downstream of the heat treatment device. The oxidation device is configured to receive the heat-treated LFP battery material from the heat treatment device and subject it to oxidative roasting in an oxidation space provided within the oxidation device. In some embodiments, the oxidation device includes a supply line for supplying an oxygen-containing gas to the oxidation space of the oxidation device. In some embodiments of the device, the oxidation device includes an oven, such as a furnace or a kiln.

[0045] In some embodiments of the device, the oxidation device includes at least one rotary kiln. In some embodiments of the device, the rotary kiln is characterized by internal heating including at least one burner. In some embodiments of the device, the at least one rotary kiln is a directly heated kiln that includes at least one burner arranged inside the kiln.

[0046] In some embodiments, at least one separation device is arranged downstream of the pulverizing device. In this separation device, the components of the pulverized LFP battery material can be separated from each other and thus supplied for more targeted processing. In some embodiments, at least one separation device is arranged upstream of the heat treatment device. In this separation device, the pulverized LFP battery material obtained from the pulverizing device can be separated into fractions with different particle sizes, and these fractions can be supplied for more targeted downstream processing. For example, the coarse materials including parts of the battery housing or metal foils can be removed from the pulverized and dried LFP battery material to reduce the energy consumption in the heat treatment and oxidation steps respectively.

[0047] In some embodiments, at least one separation device is arranged downstream of the oxidation device. In this separation device, the oxidized LFP battery material obtained from the oxidation device can be separated into fractions with different particle sizes, and these fractions can be supplied for more targeted downstream processing.

[0048] In some embodiments of the device, a filling device is arranged downstream of the oxidation device. The filling device provides the oxidized LFP battery material for further processing. In some embodiments, in this filling device, the oxidized LFP battery material is filled into a transport container. In some embodiments, at least one separation device is arranged upstream of the filling device and downstream of the oxidation device.

[0049] This disclosure also provides a method for recycling LFP battery materials. The method includes:

[0050] a) Providing LFP battery material to a comminution device,

[0051] b) Comminuting the LFP battery material in the comminution device to produce comminuted LFP battery material,

[0052] c) Transferring the comminuted LFP battery material to a heat treatment device,

[0053] d) Drying the comminuted LFP battery material and heating it to a temperature in the range of 250 °C to 500 °C, while contacting the comminuted and dried LFP battery material with an inert gas and with a reducing gas in-situ generated by the thermal decomposition of the comminuted LFP battery material,

[0054] e) Transferring the heat-treated comminuted LFP battery material to an oxidation device,

[0055] f) Oxidizing the heat-treated comminuted LFP battery material at a temperature of 500 °C to 700 °C, while contacting the heat-treated comminuted LFP battery material with an oxygen-containing gas to obtain oxidized LFP battery material.

[0056] In some embodiments, the method further includes the following steps:

[0057] g) Leaching the oxidized LFP battery material with sulfuric acid to obtain a solution containing lithium ions and copper ions,

[0058] h) Recovering copper from the solution obtained in step g), and

[0059] i) Removing impurities from the solution obtained in step h) to obtain a solution containing lithium ions.

[0060] At the beginning of the method, an LFP battery material (such as an old LFP battery) is provided to a comminution device and then comminuted in the comminution device.

[0061] In some embodiments of the method, the LFP battery material is at least one selected from the following: lithium iron phosphate batteries, lithium iron phosphate battery waste, lithium iron phosphate battery production waste, lithium iron phosphate battery cell production waste, lithium iron phosphate cathode active material, and combinations thereof.

[0062] The lithium iron phosphate battery can be disassembled, stamped, milled (e.g., in a hammer mill, a rotary mill), and / or shredded (e.g., in an industrial shredder). The active material of the battery electrode can be obtained through such mechanical processing. Light fractions (such as the housing parts made of organic plastics and aluminum foil or copper foil) can be removed, for example, by forced air flow, air separation or classification or screening.

[0063] The battery waste can originate from, for example, old batteries or production waste such as defective materials. In some embodiments, the material is obtained from mechanically treated battery waste, for example, from battery waste treated in a hammer mill, a rotary mill or an industrial shredder. Such a material can have an average particle size (D 50 ) ranging from 1 μm to 1 cm, such as 1 μm to 500 μm, and further, for example, 3 μm to 250 μm.

[0064] A larger portion of the battery waste, such as the housing, wiring and electrode carrier film, can be mechanically separated so that the corresponding materials can be excluded from the old batteries used in the method of the present disclosure. In some embodiments, the separation is accomplished by manual or automatic sorting. For example, the magnetic portion can be separated by magnetic separation, and non-magnetic metals can be separated by an eddy current separator. Other techniques can include air jigs and wind shakers.

[0065] The comminuted LFP battery material is transferred to a heat treatment device. In some embodiments of the method, the comminuted LFP battery material contains aluminum foil and cathode active material. In some embodiments, the comminuted LFP battery material contains copper, aluminum, lithium, iron, phosphorus, or combinations thereof.

[0066] In the heat treatment device, the comminuted LFP battery material is dried and heated to a temperature of 250 °C to 500 °C while contacting the comminuted LFP battery material with an inert gas and with a reducing gas in-situ generated by the thermal decomposition of the comminuted LFP battery material to obtain a heat-treated LFP battery material.

[0067] In some embodiments of the method, step b) includes the following steps:

[0068] I. Feed the material into a first comminution device and comminute the material to obtain first particles having a maximum diameter of 50 mm or less;

[0069] II. Feed the first particles obtained in step I) into a second comminution device and comminute the first particles to obtain second particles having a maximum diameter of 20 mm or less;

[0070] III. Feed the second particles obtained in step II) into a first separation device to remove a first fine fraction consisting of particles having a size of <500 μm from the second particles;

[0071] IV. Feed the second particles obtained in step III) into a third comminution device and comminute the second particles to generate a second fine fraction consisting of particles having a size of <500 μm;

[0072] V. Combine the first fine fraction and the second fine fraction.

[0073] The first and second fine fractions each consist of particles having a size of <500 μm. In other words, all the particles of the first and second fine fractions respectively pass through a sieve having a sieve aperture width of 500 μm.

[0074] In some embodiments, step V. involves sieving the first fine fraction and the second fine fraction through a sieve having a sieve aperture width of not more than 500 μm (e.g., 250 μm or less). In some embodiments, the particles remaining on the sieve are washed with water to remove the residual fine fraction adhering to the particles remaining on the sieve.

[0075] In some embodiments of the method, calcium carbonate is added to the comminuted LFP battery material before transferring the comminuted LFP battery material to a heat treatment device. In some embodiments, a stoichiometric amount of calcium carbonate relative to the total fluorine content of the comminuted LFP battery material is added. For every mol of fluorine present, 0.5 mol of calcium carbonate is added. During the heat treatment of the comminuted LFP battery material, calcium carbonate reacts with the fluorine present in the comminuted LFP battery material, thereby capturing the fluorine and preventing the formation of corrosive and toxic gases (such as hydrogen fluoride).

[0076] In some embodiments of the method, a mixture of calcium carbonate and magnesium carbonate is added to the comminuted LFP battery material before transferring the comminuted LFP battery material to a heat treatment device. In some embodiments, a stoichiometric amount of the calcium carbonate / magnesium carbonate mixture relative to the total fluorine content of the comminuted LFP battery material is added. For every mol of fluorine present, the total molar amount of calcium carbonate and magnesium carbonate added is 0.5 mol (x mol CaCO 3 + y mol MgCO 3= 0.5 mol (CaCO 3 + MgCO 3 ))。In some embodiments, before transferring the crushed LFP battery material to the heat treatment device, dolomite (CaMg(CO 3 )) 2 ) is added to the crushed LFP battery material. During the heat treatment of the crushed LFP battery material, the calcium carbonate / magnesium carbonate mixture reacts with the fluorine present in the crushed LFP battery material, thereby capturing the fluorine and preventing the formation of corrosive and toxic gases (such as hydrogen fluoride). It has been found that using a mixture of calcium carbonate and magnesium carbonate further improves the leaching efficiency of lithium and reduces the amount of iron in the leaching solution.

[0077] In some embodiments, the method disclosed herein includes providing a crushed LFP battery material at a first temperature; heating the crushed LFP battery material at a second temperature in the range of 250 °C to 500 °C, contacting the crushed LFP battery material with an inert gas and with a reducing gas in-situ generated by the thermal decomposition of the crushed LFP battery material to obtain a heat-treated LFP battery material.

[0078] In some embodiments, the method disclosed herein includes providing a crushed LFP battery material at a first temperature. In some embodiments of the method, the first temperature ranges from -50 °C to 50 °C, for example, from -10 °C to 40 °C, for example, from 0 °C to 30 °C. In a specific embodiment, the first temperature is the ambient temperature.

[0079] In some embodiments of the method, the heat treatment step includes a temperature ramp from the first temperature to the second temperature over a period of 10 minutes to 2 hours. In some embodiments of the method, the heat treatment step includes a temperature ramp from the first temperature to the second temperature over a period of 30 minutes to 1.5 hours.

[0080] In some embodiments, the temperature ramp has an average temperature increase rate of at least 5 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate of at least 10 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate of at least 15 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate of at least 20 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate of at least 25 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate of up to 50 K per minute.

[0081] In some embodiments, the temperature ramp has an average temperature increase rate ranging from 5 K to 50 K per minute. In some embodiments, the temperature ramp has an average temperature increase rate ranging from 10 K to 50 K per minute.

[0082] In some embodiments of the method, the heat treatment step includes dwelling for a period ranging from 0 minutes to 1 hour, such as 10 minutes to 45 minutes, or 15 minutes to 30 minutes, at a second temperature.

[0083] In some embodiments of the method, the heat treatment step includes dwelling at one or more intermediate temperatures ranging from a first temperature to a second temperature.

[0084] In some embodiments, the method of the present disclosure includes: providing a comminuted LFP battery material at a first temperature ranging from -50 °C to 50 °C; heating the comminuted LFP battery material at a second temperature ranging from 250 °C to 500 °C; wherein the heating step includes a temperature ramp from the first temperature to the second temperature over a period ranging from 10 minutes to 1 hour; and dwelling at the second temperature for a time ranging from 0 minutes to 1 hour.

[0085] The method of the present disclosure includes contacting the comminuted LFP battery material with an inert gas and with a reducing gas in-situ generated by thermal decomposition of the comminuted and dried battery to obtain a pyrolyzed battery material.

[0086] In some embodiments, the flow rate of the inert gas is in the range of 100 to 300 Sm 3 / h, such as 150 to 250 Sm 3 , for example 200 Sm 3 / h (standard cubic meters per hour).

[0087] In some embodiments, the inert gas comprises at least one gas selected from argon (Ar), nitrogen (N 2 ), helium (He), and mixtures thereof.

[0088] In some embodiments, the reducing gas comprises at least one gas selected from the group consisting of hydrocarbons, hydrogen (H 2 ), carbon monoxide (CO), and mixtures thereof.

[0089] In some embodiments of the method, the reducing gas comprises: 5 vol% to 70 vol% of C 1 to C 10 hydrocarbons, 5 vol% to 95 vol% of carbon dioxide (CO 2 ), 0.1 vol% to 10 vol% of carbon monoxide (CO), and 0.1 vol% to 15 vol% of H 2 ; where each vol% is based on the total volume of the reducing gas, and the vol% of C 1 to C 10 hydrocarbons plus the vol% of CO 2 plus the vol% of H 2 is less than or equal to 100%.

[0090] In some embodiments of the method, the reducing gas comprises: 5 vol% to 70 vol% of C 1 to C 10 hydrocarbons, 5 vol% to 45 vol% of C 1 to C 10 oxohydrocarbons, and 0.1 vol% to 15 vol% of H 2 ; where each vol% is based on the total volume of the reducing gas, and the vol% of C 1 to C 10 hydrocarbons plus the vol% of C 1 to C 10 oxohydrocarbons plus the vol% of H 2 is less than or equal to 100%.

[0091] In some embodiments of the method, the heat treatment step is carried out in a rotary kiln. In some embodiments of the method, the kiln is filled with 5% to 20% of the total volume of the kiln, such as 7% to 16%, such as 8% to 12% of the crushed LFP battery material.

[0092] In some embodiments of the method, at least one screw conveyor is used to feed the crushed LFP battery material into the kiln.

[0093] In some embodiments of the method, the kiln rotates at 0.5 to 3 rpm. In some embodiments of the method, the kiln rotates at 1.4 to 2.6 rpm. In some embodiments of the method, the kiln rotates at 1.8 to 2.2 rpm.

[0094] In some embodiments of the method, an overpressure is maintained in the kiln during operation to prevent air from entering the kiln.

[0095] In some embodiments of the method, the hot gas passes through the kiln in the same direction as the process material (cocurrent). In some embodiments of the method, the crushed LFP battery material and the inert gas are fed into the rotary kiln in cocurrent flow. Cocurrent flow ensures that no dust escapes from the upper end of the kiln.

[0096] In some embodiments of the method, the rotary kiln is heated by an external heating element using electricity. In some embodiments of the method, the kiln includes a number of heating zones.

[0097] Transfer the heat-treated LFP battery material to an oxidation device and then heat it at a temperature of 500 °C to 700 °C, such as 550 °C to 650 °C, such as 580 °C to 600 °C, while bringing the heat-treated LFP battery material into contact with an oxygen-containing gas to obtain an oxidized LFP battery material. In some embodiments of the method, the oxidation step includes a residence time at this temperature in the range of 0 minutes to 2 hours, such as 15 minutes to 105 minutes, or 30 minutes to 90 minutes.

[0098] In the oxidation device, bring the heat-treated LFP battery material into contact with an oxygen-containing gas. In some embodiments of the method, the oxygen-containing gas is air. In some embodiments of the method, the oxygen-containing gas is lean oxygen air, i.e., a mixture of nitrogen and oxygen with an oxygen content of less than 20.95 vol.-%. In some embodiments of the method, lean oxygen air with an oxygen content of less than 8 vol.-%, such as less than 5 vol.-%, such as 1 vol.-% to 3 vol.-% is used. In some embodiments of the method, the oxygen-containing gas has an oxygen content of more than 21 vol.-%.

[0099] In some embodiments, the flow rate of the oxygen-containing gas is in the range of 700 to 3,000 Sm 3 / h, such as 750 to 2,500 Sm 3 / h, such as 700 to 800 Sm 3 / h, or 1,500 to 2,500 Sm 3 / h (standard cubic meters per hour).

[0100] In some embodiments, the oxidized LFP battery material contains Li with a molar ratio of about 2:1, such as in the range of 1.8:1 to 2.2:1 3 Fe 2 (PO 4 ) 3 and Fe 2 O 3 .

[0101] This disclosure also provides the use of the oxidized LFP battery material of this disclosure in recovering valuable materials from LFP battery materials (e.g., old LFP batteries). In some embodiments, the oxidized LFP battery material is used as an intermediate in a downstream leaching process.

[0102] In some embodiments of the method, the oxidized LFP battery material obtained from the oxidation step is subsequently leached with sulfuric acid to obtain an aqueous solution containing one or more valuable metal ions, such as a solution containing lithium ions and copper ions. In some embodiments, the solution further contains iron and phosphorus. In some embodiments, the solution further contains impurities such as nickel, cobalt, and / or manganese. The solution containing one or more valuable metal ions can be further purified via, for example, solvent exchange, ion exchange, precipitation, extraction, and / or electrolysis.

[0103] In some embodiments of the method, the molar amount of sulfuric acid used for leaching the oxidized LFP battery material is in the range of: 1.0*(0.5 times the molar amount of lithium + the molar amount of copper) to 2.0*(0.5 times the molar amount of lithium + the molar amount of copper) present in the oxidized LFP material, as determined by elemental analysis. In some embodiments of the method, the molar amount of sulfuric acid used for leaching the oxidized LFP battery material is in the range of: 1.0*(0.5 times the molar amount of lithium + the molar amount of copper) to 1.5*(0.5 times the molar amount of lithium + the molar amount of copper) present in the oxidized LFP material, as determined by elemental analysis. It has been found that when there is an excess of sulfuric acid in the leaching step, a large amount of iron and phosphorus are leached from the oxidized LFP battery material.

[0104] In some embodiments of the method, the leaching is carried out at a temperature of 90 °C to 100 °C, such as 95 °C to 100 °C, such as 98 °C to 100 °C. It has been found that high temperature significantly increases the selectivity of the leaching process for lithium and copper; and less iron and phosphorus are dissolved. In addition, iron(III) phosphate (FePO 4 ) is formed and precipitates from the solution.

[0105] In some embodiments of the method, the weight ratio of liquid to solid in the leaching step is in the range of 3:1 to 6:1, such as 3:1 to 5:1, such as 3:1 to 4:1. It has been found that using the weight ratio of liquid to solid within the specified range significantly increases the selectivity of the leaching process for lithium and copper; and less iron and phosphorus are dissolved.

[0106] In some embodiments of the method, the duration of the leaching step is in the range of 30 minutes to 3 hours, such as 2 hours.

[0107] After the leaching step, the formed solution is separated from the solid, for example, by filtration or sedimentation.

[0108] In some embodiments of the method, copper is recovered from the solution containing lithium ions and copper ions. In some embodiments of the method, copper (Cu 0 ) is recovered from the solution by displacement with iron powder (Fe 0)。In some embodiments of the method, copper is recovered from the solution by precipitating copper sulfide (CuS) from the solution. In some embodiments of the method, copper is recovered from the solution by solvent extraction.

[0109] In some embodiments of the method, impurities are recovered from the copper ion-depleted solution. In some embodiments of the method, the pH value of the solution is increased to a value in the range of -PPT pH ≈ 10 - 11 to precipitate the impurities. In some embodiments of the method, tetrafluoroaluminate [AlF 4 - is added to the solution to precipitate the impurities. In some embodiments of the method, a cation exchanger loaded with calcium ions is used to remove the impurities by ion exchange, resulting in the precipitation of calcium salts from the solution.

[0110] After removing the impurities, a solution containing lithium ions is obtained. In some embodiments of the method, the solution is directly used as a feed for chemical reactions, such as the preparation of cathode active materials (CAM) for batteries. In some embodiments of the method, lithium carbonate is precipitated from the solution. In some embodiments of the method, lithium phosphate is precipitated from the solution.

[0111] Examples

[0112] Example 1

[0113] Three separate batches of 150 g of LFP cathode material were filled into ceramic crucibles, which were placed in a muffle furnace and heated to 450 °C within 2 h. During the heating, the air inlet of the furnace was opened, and air was allowed to pass through the furnace chamber at an undefined flow rate. After maintaining the temperature at 450 °C for 2 h and then cooling to ambient temperature, the products were combined and a total of 456.7 g was obtained.

[0114] Leaching with different solid-liquid ratios

[0115] 20 g of the product was dispersed in a) 94.3 g, b) 74.3 g, c) 54.3 g of deionized water and heated to 100 °C with stirring. 5.7 g of 96% sulfuric acid was slowly added to all three reaction vessels within 15 minutes. After 2 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove the solids. After washing with 20 mL of deionized water and drying under reduced pressure, solid residues of a) 21.1 g, b) 21.3 g, c) 21.7 g were obtained. Lithium, iron, and phosphorus were leached with the following efficiencies: a) 95.1%, 0.3%, and 7.8%; b) 97.9%, 0.2%, and 7.0%; c) 92.3%, 0.1%, and 5.1%.

[0116] Leaching at different temperatures ​

[0117] Disperse 20 g of the product in 94.3 g of deionized water and d) stir at room temperature, e) heat to 40 °C with stirring, f) heat to 70 °C with stirring. Slowly add 5.7 g of 96% sulfuric acid to all three reaction vessels within 15 minutes. After 2 h at the respective temperatures, allow the mixture to cool to ambient temperature and then filter to remove the solid. After washing with 20 mL of deionized water and drying under reduced pressure, 14.3 g, e) 16.3 g, f) 17.0 g of solid residue are obtained. Lithium, iron, and phosphorus are leached with the following efficiencies respectively: d) 59.5%, 21.8%, and 37.7%; e) 67.4%, 14.7%, and 29.5%; f) 67.1%, 11.9%, and 26.2%.

[0118] Example 2 (Comparison)

[0119] Disperse 20 g of the mixed electrode material from LFP battery waste in a) 96.5 g, b) 92.9 g, c) 89.4 g, d) 80.0 g of deionized water and heat to 100 °C with stirring. Slowly add a) 3.5 g, b) 7.1 g, c) 10.6 g, d) 20.0 g of 96% sulfuric acid within 15 minutes. After 2 h at 100 °C, allow the mixture to cool to ambient temperature and then filter to remove the solid. After washing with 20 mL of deionized water and drying under reduced pressure, a) 14.3 g, b) 10.7 g, c) 7.3 g, d) 7.5 g of solid residue are obtained. Lithium, iron, phosphorus, and copper are leached with the following efficiencies respectively: a) 50.8%, 36.8%, 32.5%, and 0.0%; b) 87.2%, 84.9%, 71.2%, and 0.0%; c) 97.9%, 97.9%, 96.7%, and 0.0%; d) 98.0%, 98.2%, 97.3%, and 0.0%.

[0120] Example 3 (Comparison)

[0121] Place 50 g of the mixed electrode material from LFP battery waste (containing 3.5 wt.-% fluorine relative to the total weight of the mixed electrode material) into a quartz glass rotary kiln and heat to 500 °C within 2 h. During heating, the kiln remains stationary and air is passed through the kiln at a flow rate of 30 L / h. After maintaining the temperature at 500 °C for 2 h and then cooling the kiln to ambient temperature, 44.3 g of a reddish-brown solid is obtained as the product. Pass the volatile products generated during the heat treatment through an aqueous KOH solution (10 wt.-%). After that, measure the fluorine content of the KOH solution, and it is found that 68.6% of the initial fluorine content of the mixed LFP electrode material has volatilized.

[0122] Leaching

[0123] Disperse 20 g of the product in a) 89.4 g, b) 96.0 g of deionized water and heat to 100 °C with stirring. Slowly add a) 10.6 g, b) 4 g of 96% sulfuric acid within 15 minutes. After 2 h at 100 °C, allow the mixture to cool to ambient temperature and then filter to remove solids. After washing with 20 mL of deionized water and drying under reduced pressure, obtain a) 9.4 g, b) 17.9 g of solid residue. Lithium, iron, and phosphorus are leached with the following efficiencies respectively: a) 91.5%, 62.6%, and 73.1%; b) 89.3%, 7.7%, and 18.0%. For a), copper can be leached with an efficiency of 78.2%.

[0124] Example 4 (Comparison)

[0125] Place 50 g of the mixed electrode material from LFP battery waste (containing 3.5 wt.-% fluorine relative to the total weight of the mixed electrode material) into a quartz glass rotary kiln and heat to 500 °C within 2 h. During heating, the kiln remains stationary and an inert gas is passed through the kiln at a flow rate of 30 L / h. After maintaining the temperature at 500 °C for 2 h and then cooling the kiln to ambient temperature, obtain 45.1 g of a black solid as the product. Allow the volatile products generated during the heat treatment to pass through an aqueous KOH solution (10 wt.-%). After that, measure the fluorine content of the KOH solution and find that 91.4% of the initial fluorine content of the mixed LFP electrode material has volatilized.

[0126] Leaching

[0127] Disperse 20 g of the product in 96.0 g of deionized water and heat to 100 °C with stirring. Slowly add 4 g of 96% sulfuric acid within 15 minutes. After 2 h at 100 °C, allow the mixture to cool to ambient temperature and then filter to remove solids. After washing with 20 mL of deionized water and drying under reduced pressure, obtain 14.5 g of solid residue. Lithium, iron, and phosphorus are leached with efficiencies of 45.3%, 36.9%, and 34.8% respectively.

[0128] Example 5 (Comparison)

[0129] 100 g of a mixed electrode material from LFP battery waste (containing 0.27 wt.-% fluorine relative to the total weight of the mixed electrode material) was placed in a quartz glass rotary kiln and heated to 600 °C within 105 min. During heating, the kiln was rotated (1 rpm) and air was passed through the kiln at a flow rate of 40 L / h. After maintaining the temperature at 600 °C for 16 h and then cooling the kiln to ambient temperature, 73.0 g of a reddish-brown solid was obtained as the product. The volatile products generated during the heat treatment were passed through an aqueous KOH solution (10 wt.-%). Subsequently, the fluorine content of the KOH solution was measured, and it was found that 94.3% of the initial fluorine content of the mixed LFP electrode material had volatilized.

[0130] Leaching

[0131] 20 g of the product was dispersed in a) 96.0 g, b) 90.0 g of deionized water and heated to 100 °C with stirring. 4.0 g, b) 10.0 g of 96% sulfuric acid was slowly added within 15 min. After 2 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove the solid. After washing with 20 mL of deionized water and drying under reduced pressure, 16.4 g, b) 14.5 g of solid residue was obtained. Lithium, iron, phosphorus, and copper were leached with the following efficiencies respectively: a) 69.1%, 13.6%, 25.4%, and 31.5%; b) 94.6%, 28.4%, 16.1%, and 78.1%.

[0132] Example 6

[0133] 101.4 g of a mixed electrode material from LFP battery waste (containing 4.15 wt.-% fluorine relative to the total weight of the mixed electrode material) was placed in a quartz glass rotary kiln and heated to 600 °C within 105 min together with CaCO₃ added in the exact stoichiometric amount to combine all the fluorine into CaF₂. 2 CaCO₃ 3 During heating, the kiln was rotated (1 rpm) and air was passed through the kiln at a flow rate of 40 L / h. After maintaining the temperature at 600 °C for 7.5 h and then cooling the kiln to ambient temperature, 72.9 g of a reddish-brown solid was obtained as the product. The volatile products generated during the treatment were passed through an aqueous KOH solution (10 wt.-%). Subsequently, the fluorine content of the KOH solution was measured, and it was found that 2.3% of the initial fluorine content of the mixed LFP electrode material had volatilized.

[0134] Leaching

[0135] Disperse 20 g of the product in a) 93.5 g, b) 87.0 g of deionized water and heat to 100 °C with stirring. Slowly add a) 6.5 g, b) 13 g of 96% sulfuric acid within 15 minutes. After 2 h at 100 °C, allow the mixture to cool to ambient temperature and then filter to remove the solid. After washing with 20 mL of deionized water and drying under reduced pressure, obtain a) 20.0 g, b) 16.8 g of solid residue. Lithium, iron, phosphorus, and copper are leached with the following efficiencies respectively: a) 90.0%, 7.6%, 8.7%, and 50.3%; b) 95.2%, 32.3%, 31.1%, and 94.2%.

[0136] Example 7

[0137] Mix 50.9 g of a mixed electrode material from LFP battery waste (containing 3.5 wt.-% fluorine relative to the total weight of the mixed electrode material) with CaCO₃ in the exact stoichiometric addition amount that combines all fluorine in the form of CaF₂ 2 3 Place it in a quartz glass rotary kiln. Place the reaction vessel under an inert atmosphere and heat to a first temperature of 300 °C at a rate of 15 K / min. After a holding time of 20 min at 300 °C, raise the temperature to 550 °C within 20 min. Then replace the inert gas with air and introduce air into the vessel at a flow rate of 50 L / h. After maintaining the temperature at 550 °C for another 1 h and then cooling the kiln to ambient temperature, obtain 43.2 g of a reddish-brown solid as the product. During heating, rotate the kiln (1 rpm) and allow the volatile products generated during the heat treatment to pass through a KOH aqueous solution (10%). Then measure the fluorine content of the KOH solution, and it is found that none of the initial fluorine content of the mixed LFP electrode material has volatilized.

[0138] Example 8

[0139] Repeat Example 7 with a larger amount of the mixed electrode material from LFP battery waste. Fill 250 g of the obtained product into a ceramic crucible, place the ceramic crucible in a muffle furnace and heat to 500 °C within 100 min. During heating, open the air inlet of the furnace and allow air to pass through the furnace chamber at an undefined flow rate. After maintaining the temperature at 500 °C for 1 h and then cooling to ambient temperature, obtain 238.2 g of a reddish-brown solid as the product.

[0140] Leaching

[0141] 20 g of the product was dispersed in 90.0 g of deionized water and heated to 100 °C with stirring. 10.0 g of 96% sulfuric acid was slowly added within 15 minutes. After 2 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove solids. After washing with 20 mL of deionized water and drying under reduced pressure, 15.8 g of solid residue was obtained. Lithium, iron, phosphorus, and copper were leached with efficiencies of 94.5%, 37.1%, 37.0%, and 97.9%, respectively.

[0142] Example 9

[0143] 76.4 g of a mixed electrode material from LFP battery waste (containing 3.5 wt.-% fluorine relative to the total weight of the mixed electrode material) was placed with CaCO₃ in a stoichiometric addition amount to combine all fluorine in the form of CaF₂ into a quartz glass rotary kiln. 2 3 The reaction vessel was placed under an inert atmosphere and heated to a first temperature of 300 °C at a rate of 5 K / min. After a holding time of 60 min at 300 °C, the inert gas was replaced with air, air was introduced into the vessel at a flow rate of 50 L / h, and the temperature was raised to 600 °C within 60 min. After holding the temperature at 600 °C for an additional 6 h and then cooling the kiln to ambient temperature, 53.9 g of a reddish-brown solid was obtained as the product. During heating, the kiln was occasionally rotated manually, and the volatile products generated during the process were passed through an aqueous KOH solution (10%). It was found that 2.9% of the initial fluorine content of the mixed LFP electrode material had volatilized.

[0144] Leaching

[0145] 20 g of the product was dispersed in 94.7 g of deionized water and heated to 100 °C with stirring. 5.3 g of 96% sulfuric acid was slowly added within 15 minutes. After 2 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove solids. After washing with 20 mL of deionized water and drying under reduced pressure, 18.5 g of solid residue was obtained. Lithium, iron, phosphorus, and copper were leached with efficiencies of 83.9%, 4.4%, 19.1%, and 52.4%, respectively.

[0146] Example 10

[0147] LFP battery waste was mixed with a single-component or two-component alkaline earth F scavenger (SCV) system in a stoichiometric ratio of fluoride to alkaline earth metal (F:M) of 1.6:1 - 2.1:1. The compositions of the starting materials used are shown in Tables 1 and 2. EA

[0148] Table 1 ​​

[0149] BM C F Al Cu Fe Li Mg P 1 28.50％ 3.50％ 2.10％ 5.40％ 17.20％ 2.40％ 0.01％ 12.0％ 2 41.40％ 3.60％ 1.90％ 2.40％ 13.70％ 2.20％ 0.03％ 8.30％

[0150] Table 2

[0151] Test BM SCV 1 SCV 1 [g] SCV 2 SCV 2 [g] <![CDATA[F:M EA > <![CDATA[F 之前 > <![CDATA[F 之后 > I 1 / / MgO 1.5 2.05:1 3.5％ 3.7％ II 1 <![CDATA[CaCO 3 > 9.4 / / 1.96:1 3.5％ 3.3％ III 2 <![CDATA[CaCO 3 > 5.2 <![CDATA[MgCO 3 > 4.4 1.63:1 3.2％ 3.7％ IV* 2 / / / / / / / V* 1 / / / / / 3.5％ 0.3％

[0152] *Comparative Example

[0153] The material was placed in a quartz glass reaction vessel and first heat-treated under inert conditions at a temperature of 300 °C - 550 °C for 1 - 2 h, and then calcined under aerobic conditions at 500 °C - 550 °C for 1 - 2 h.

[0154] In Tests I - III, the fluoride was quantitatively retained in the solid (>95%). The conditions of Test IV were kept similar, except that no additional scavenger was added. In Test V, no scavenger was added and the LFP battery waste material was heat-treated under inert conditions at a temperature of 500 °C for 2 h. All products were obtained as red-brown solids.

[0155] Leaching Example A

[0156] 20 g of Product I was dispersed in 92.5 g of deionized water and heated to 100 °C with stirring. 7.5 g of 96% sulfuric acid was slowly added within 15 minutes. After 2 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove the solid. After washing with deionized water and drying under reduced pressure, 18.8 g of solid residue and 105.1 g of leaching solution were obtained.

[0157] Leaching Example B

[0158] 20 g of Product II was dispersed in 92.5 g of deionized water and heated to 100 °C with stirring. 7.5 g of 96% sulfuric acid was slowly added within 15 minutes. After 8 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove the solid. After washing with deionized water and drying under reduced pressure, 20 g of solid residue and 103.8 g of leaching solution were obtained.

[0159] Leaching Example C

[0160] 20 g of Product III was dispersed in 110 g of deionized water and heated to 100 °C with stirring. 10 g of 96% sulfuric acid was slowly added within 15 minutes. After 3 h at 100 °C, the mixture was allowed to cool to ambient temperature and then filtered to remove the solid. After washing with deionized water and drying under reduced pressure, 19 g of solid residue and 117.6 g of leaching solution were obtained.

[0161] Leaching Example D

[0162] Disperse 20 g of Product IV in 110 g of deionized water and heat to 100 °C with stirring. Slowly add 10 g of 96% sulfuric acid within 15 minutes. After 3 h at 100 °C, allow the mixture to cool to ambient temperature and then filter to remove the solid. After washing with deionized water and drying under reduced pressure, 18 g of solid residue and 115.9 g of leaching solution can be obtained.

[0163] The measured leaching efficiency is shown in Table 3, and the composition of the obtained leaching solution is shown in Table 4.

[0164] Table 3

[0165] Test Li-LE Fe-LE P-LE F-LE Mg-LE A 95.6％ 5.7％ 8.1％ / 41.3％ B 91.8％ 14.1％ 5.5％ / / C 96.8％ 4.3％ 6.4％ 47.3％ 25.3％ D 92.3％ 7.5％ 8.2％ 77.9％ /

[0166] Table 4

[0167] Test Li Fe P Cu F Ca Mg A 0.51％ 0.22％ 0.18％ 0.49％ n.d. n.d. 0.20％ B 0.46％ 0.55％ 0.13％ 0.83％ n.d. n.d. n.d. C 0.39％ 0.11％ 0.10％ 0.48％ 0.29％ 0.049％ 0.064％ D 0.41％ 0.21％ 0.14％ 0.53％ 0.47％ n.d. n.d.

[0168] Analysis method

[0169] Determination of Leaching Efficiency

[0170] The leaching efficiency (LE) is determined using the elemental content measured by ICP-OES. Unless otherwise stated, the leaching efficiency is determined using the elemental content measured in the mother liquor.

[0171] Using the following formula:

[0172]

[0173] Where

[0174] E represents a given element,

[0175] ML represents the mother liquor,

[0176] E ICP-ML is the percentage-based content measured in the mother liquor,

[0177] m(E ML ) is the weight content of the element in the mother liquor,

[0178] m(E Max ) is the maximum recovery of the element, which is based on the amount of the element in the solid before leaching, and

[0179] LE E is the leaching efficiency of the corresponding element.

[0180] In Examples 2c, 2d and 6b, the leaching efficiency was determined from the filtration residue.

[0181] All calculations were similar to Equations (1) and (2), except for each instance where FC (filter cake) was used instead of ML. The corresponding LE E was:

[0182]

[0183] Proportion of fluorine volatilized

[0184] All calculations were performed using the elemental content determined by ICP - OES. Fluoride volatilization was detected by analyzing the fluorine content of the solid before and after heat treatment, or alternatively by analyzing the fluorine content of the 10% KOH scrubber liquid.

[0185]

[0186] F% was the percentage of fluoride in the solid or scrubber liquid, respectively.

[0187] Elemental analysis

[0188] This section describes the analytical methods for quantitatively determining the composition of the composites of the present disclosure.

[0189] Fluorine content

[0190] The determination of fluorine used a combination of combustion and measurement by a fluoride ion - selective electrode.

[0191] Combustion

[0192] Approximately 1 - 100 mg of the sample was weighed into a combustion boat. Capsules made of gelatin or tin could be used for sample weighing and transfer. Add V 2 O 5 to facilitate combustion. The boat was introduced into a combustion tube heated to approximately 1,000 °C - 1,100 °C via a sample application device. The sample was burned in a stream of oxygen containing water vapor. During combustion, the fluorine - containing components formed hydrogen fluoride. The combustion gas containing the formed hydrogen fluoride was absorbed in an absorption solution. A total ion strength adjustment buffer (e.g., TISAB IV buffer solution (ASTM D 1179)) was used as the absorption solution. The solution was transferred to an ion - sensitive measurement cell and filled to 50 mL with TISAB and ultrapure water (1:1).

[0193] The combustion system used was a Mitsubishi AQF - 2100H automatic rapid furnace (a1 - envirosciences GmbH, Düsseldorf 40595, Germany).

[0194] · Oven inlet temperature: approximately 1,000 °C

[0195] · Oven outlet temperature: approximately 1,100 °C

[0196] · Combustion gas (oxygen): approximately 200 mL / min

[0197] · Carrier gas (argon): approximately 100 mL / min

[0198] · Water flow rate: 0.2 mL / min

[0199] Detection by fluoride ion selective electrode

[0200] In the absorption solution, fluoride is measured by a fluoride ion selective electrode (e.g., ISE 6.0502.150, Metrohm GmbH, 70794 Filderstadt, Germany). For quantification, external calibration of the electrode is performed using fluoride standard solutions of different concentrations (e.g., 0.1, 1.0, 10, and 100 mg / L fluoride). The calibration solutions are automatically prepared by diluting a fluoride stock solution with TISAB solution and ultrapure water (1:1).

[0201] Metal content

[0202] Elemental analysis is performed using a combination of acid digestion and alkaline borate fusion digestion and analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) on an inductively coupled plasma optical emission spectrometer (e.g., Agilent 5110 ICP-OES, Agilent Technologies Germany GmbH & Co. KG, Waldbronn 76337, Germany).

[0203] An aliquot of the sample material (e.g., approximately 0.2 g) is weighed into a volumetric flask and dissolved in 30 ml of HCl under gentle heating. After cooling, the insoluble residue is filtered out and incinerated with the filter paper in a Pt crucible above an open flame. Subsequently, the residue is calcined in a muffle furnace at approximately 600 °C and then combined with 1.0 g of K 2 CO 3 -Na 2 CO 3 / Na 2 B 4 O 7The flux mixture (4:1) is mixed and melted over an open flame until a clear melt is obtained. After cooling, the melt cake is dissolved in deionized (DI) water under gentle heating, and 12 ml of HCl is added. Finally, this solution is added to the initial filtered solution in a volumetric flask, and the volume is made up to its final volume with DI water. Each sample is prepared in triplicate. A blank sample is prepared in a similar manner.

[0204] The digestion solution is analyzed by inductively coupled plasma - optical emission spectrometry (ICP - OES) using external calibration. For some samples, the digestion solution can be diluted before analysis, for example, diluted according to the concentration and calibration range of the corresponding analyte.

[0205] Phosphorus content

[0206] The phosphorus content is determined by a combination of acid dissolution and alkaline - borate fusion digestion followed by measurement via inductively coupled plasma optical emission spectrometry (ICP - OES).

[0207] An aliquot of the sample material between 0.13 g and 0.18 g is weighed into a volumetric flask and dissolved in HCl (approx. 6 mol / l) under gentle heating. After cooling, the insoluble residue is filtered out and incinerated in a Pt crucible above an open flame together with the filter paper. Subsequently, the residue is calcined in a muffle furnace at approximately 600 °C and then mixed with 1.0 g of K 2 CO 3 -Na 2 CO 3 / Na 2 B 4 O 7 The flux mixture (4:1) is mixed and melted over an open flame until a clear melt is obtained. After cooling, the melt cake is dissolved in DI water under gentle heating, and 12 ml of HCl is added. Finally, this solution is added to the initial filtered solution in a volumetric flask, and the volume is made up to 100 ml with DI water. Each sample is prepared in triplicate. A blank sample is prepared in a similar manner.

[0208] The digestion solution is analyzed by inductively coupled plasma - optical emission spectrometry (ICP - OES) using an ICP - OES spectrometer (Agilent 5110 ICP - OES, Agilent Technologies Germany GmbH, Waldbronn 76337, Germany) under the following conditions: wavelength: P(R) 178.222 nm, internal standard: Sc(R) 361.383 nm, calibration: external, dilution factor: 1 (direct measurement).

[0209] Carbon content

[0210] The carbon content was determined by elemental analysis in an automatic analyzer (vario EL Cube, Elementar Analysensysteme GmbH, Langenselbold 63505, Germany). The sample (2 - 3 mg) was weighed into a tin capsule. Using copper oxide as a combustion catalyst, the capsule with the sample was burned in a helium / oxygen atmosphere at approximately 1100 °C. After separating the combustion gases by chromatography, the carbon was determined as CO 2 and measured. Detection and quantification were performed by measuring the thermal conductivity using a TCD.

Claims

1. An apparatus for recycling lithium iron phosphate (LFP) battery materials, the apparatus comprising i) a comminution device for comminuting LFP battery materials in a comminution space, ii) a heat treatment device arranged downstream of the comminution device, which is configured to receive the comminuted LFP battery materials and subject them to a heat treatment in an inert or reducing atmosphere in a heat treatment space provided within the heat treatment device, iii) an intermediate storage device arranged between the comminution device and the heat treatment device, which includes agitation means configured to keep the comminuted LFP battery materials received in an intermediate storage space of the intermediate storage device in motion, iv) an oxidation device arranged downstream of the heat treatment device, which is configured to receive the heat-treated LFP battery materials from the heat treatment device and is configured to oxidize the comminuted and heat-treated LFP battery materials in an oxidation space provided within the oxidation device in an oxidizing atmosphere at an elevated temperature.

2. The apparatus according to claim 1, further comprising v) at least one reactor for recovering valuable materials from the oxidized LFP battery materials.

3. The apparatus according to claim 1 or 2, wherein, the heat treatment device includes a rotary kiln.

4. The apparatus according to any one of claims 1 to 3, wherein, the oxidation device includes at least one rotary kiln.

5. The apparatus according to claim 4, wherein, the at least one rotary kiln is a directly heated kiln, the directly heated kiln including at least one burner arranged inside the kiln.

6. The apparatus according to any one of claims 1 to 5, further comprising vi) at least one separation device arranged downstream of the comminution device.

7. The apparatus according to claim 6, wherein, at least one separation device is arranged downstream of the oxidation device.

8. The apparatus according to any one of claims 1 to 7, further comprising vii) a filling device arranged downstream of the oxidation device.

9. The apparatus according to any one of claims 1 to 8, comprising i1) a first comminution device for comminuting LFP battery materials to a first degree of comminution in a first comminution space, and i2) a second comminution device arranged downstream of the first comminution device and configured to further comminute the LFP battery materials to a second degree of comminution in a second comminution space, the second degree of comminution being greater than the first degree of comminution.

10. A method for recycling LFP battery materials, the method comprising a) providing LFP battery materials to a comminution device, b) comminuting the LFP battery materials in the comminution device to produce comminuted LFP battery materials, c) transferring the comminuted LFP battery materials to a heat treatment device, d) drying the comminuted LFP battery materials and heating them to a temperature in the range of 250 °C to 500 °C while bringing the comminuted and dried LFP battery materials into contact with an inert gas and with a reducing gas in-situ generated by the thermal decomposition of the comminuted LFP battery materials. e) Transfer the heat-treated and pulverized LFP battery material to an oxidation device. f) Oxidize the heat-treated and pulverized LFP battery material at a temperature of 500 °C to 700 °C while contacting the heat-treated and pulverized LFP battery material with an oxygen-containing gas to obtain an oxidized LFP battery material.

11. The method according to claim 10, further comprising the following steps: g) Leach the oxidized LFP battery material with sulfuric acid to obtain a solution containing lithium ions and copper ions. h) Recover copper from the solution obtained in step g), and i) Remove impurities from the solution obtained in step h) to obtain a solution containing lithium ions.

12. The method according to claim 10 or 11, wherein, before transferring the pulverized LFP battery material to the heat treatment device, calcium carbonate in a stoichiometric amount relative to the total fluorine content of the pulverized LFP battery material is added to the pulverized LFP battery material.

13. The method according to claim 11 or 12, wherein, the molar amount of sulfuric acid used for leaching the oxidized LFP battery material is in the following range: 1.0*(0.5 times the molar amount of lithium + the molar amount of copper) to 2.0*(0.5 times the molar amount of lithium + the molar amount of copper) present in the oxidized LFP material, as determined by elemental analysis.

14. The method according to any one of claims 11 to 13, wherein, the weight ratio of liquid to solid in the leaching step g) is in the range of 3:1 to 6:

1.

15. The method according to any one of claims 11 to 14, wherein, the leaching step g) is carried out at a temperature of 95 °C to 100 °C.

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