PROCESS FOR THE RECOVERY OF LITHIUM FROM WASTE LITHIUM-ION BATTERIES.

Abstract

A process for recovering lithium from waste lithium-ion batteries, or parts thereof, is disclosed. The process comprises the steps of: (a) providing a particulate material containing a transition metal compound and / or a transition metal, wherein the transition metal is selected from the group consisting of Mn, Ni, and Co, and wherein, furthermore, at least a fraction of said Ni and / or Co, if present, is in an oxidation state lower than +2 and at least a fraction of said Mn, if present, is manganese(II) oxide; wherein the particulate material further contains a lithium salt and a fluoride salt, and wherein the particulate material optionally contains calcium provided that the element ratio between calcium and fluorine is 1.7 or less or zero; (b) treating the material provided in step (a) with a polar solvent and an alkaline earth hydroxide; and (c) separating the solids from the liquid, optionally followed by washing the solid residue with a polar solvent, such as water, provides satisfactory separation of high-purity lithium and recovery of valuable transition metals.

Description

PROCESS FOR THE RECOVERY OF LITHIUM FROM WASTE LITHIUM-ION BATTERIES The present invention relates to a process for recovering lithium from spent lithium-ion batteries containing at least one of the transition metals nickel, manganese, and cobalt; the process specifically relates to separating lithium from unwanted impurities by extracting lithium as lithium hydroxide from particulate material obtained from lithium-ion batteries, in particular, the cell material thereof, generally after discharge, crushing, and reduction at high temperature. Electrical energy storage is a matter of growing interest. Efficient electrical energy storage allows for the generation of electricity when and where it is needed, at the most advantageous times. Secondary lithium batteries are of particular interest for energy storage because they provide high energy density due to lithium's low atomic weight and high ionization energy. They are increasingly used as a power source for many portable electronic products, such as cell phones, laptops, and mini-cameras, as well as for electric vehicles. However, the growing demand for raw materials such as lithium, cobalt, and nickel will present challenges in the future. The lifespan of lithium-ion batteries is not unlimited. Therefore, an increasing number of spent lithium-ion batteries are expected to emerge. Since they contain important transition metals such as cobalt and nickel, as well as lithium, spent lithium-ion batteries can be a valuable source of raw materials for a new generation of lithium-ion batteries. For this reason, research efforts have increased to recycle transition metals and lithium from used lithium-ion batteries or from batteries or parts that do not meet specifications and requirements; such off-specification materials and production waste can also constitute a source of raw materials. Two main processes have been used for raw material recovery. One of the main processes is based on melting the corresponding battery slag. This yields a metal alloy containing Ni and Co, while the lithium is lost in the waste, from which recovery is very difficult. This metal alloy can be processed hydrometallurgically to extract the metals, for example, transition metals. The other main process is the direct hydrometallurgical processing of battery slag materials. The principles have been disclosed in WO 2017 / 091562 and in J. Power Sources, 2014, 262, pp. 255 ff. Such hydrometallurgical processes will provide transition metals as aqueous solutions, for example, as sulfate solutions, or in precipitated form, for example, as hydroxides, either separated or already in the desired stoichiometries for the fabrication of a new active cathode material. In the latter case, the composition of the metal salt solutions can be adjusted to the desired stoichiometries by adding single-metal components. Rrn Lnn / zznz / E / YiAi WO 2017 / 091562 describes the coprecipitation of transition metals. WO 2014 / 180743 describes a coprecipitation process using ammonia or amines. In general, batteries are first disassembled into modules or even individual cells. In the case of direct hydrometallurgical processing, the battery slag is mechanically processed to separate the larger components of the casing and wiring. The active electrode materials—graphite, lithium transition metal oxides, and cathode anode—along with some impurities, form a fine powder called black powder or black mass, which serves as the feed for subsequent stages of the hydrometallurgical process. In some processes, the battery slag undergoes heat treatment or a pyrolysis stage at temperatures well below the melting point of the transition metals contained in the slag. This treatment differs from a smelting process, which is performed above the melting point of the transition metals in the slag. These heat-treated black masses can be obtained from the treatment of batteries in waste incineration furnaces. Waste batteries, battery modules, or battery cells are fed into the incineration furnace where the battery charge is partially burned. The product of this treatment is cooled and mechanically processed using any suitable crushing or grinding device to separate a metallic fraction from the powdered black mass. These black masses are low-reactivity materials under normal conditions and can therefore be easily transported. Several authors describe a heat treatment of waste lithium-ion batteries or components containing the active electrode materials of these types of batteries at temperatures above 400°C. This heat treatment results in the complete evaporation of the electrolyte solvents contained in the battery and the decomposition of polymeric components. The materials obtained from this heat treatment can be subjected to various mechanical treatments and separation operations to separate different metal fractions and a powdered substance comprising primarily the active electrode materials of the anode (graphite) and cathode (a lithium-containing transition metal material). These powders are often referred to as "black mass," "black powder," or "active mass."Depending on the reaction conditions, the final material is often at least partially reduced, thus containing metallic Ni and Co phases, manganese oxide phases, and lithium salts such as LiOH, Li2CO3, LiF, LiAIO2, and Li3PO4. Reduction occurs under reducing conditions during heat treatment by introducing reducing gases, such as hydrogen or carbon monoxide, or at temperatures above 500°C due to the carbonaceous material contained in the waste battery material, namely graphite and soot. J. L. et al., J. Hazard. Mat. 2016, 302, 97 ff., disclose a wet magnetic separation / oxygen-free roasting process for recycling cobalt, lithium carbonate, and graphite from spent LiCoO2 / graphite batteries. In JP2012229481, waste batteries are treated in several stages so that the fluorine contained in the batteries is bonded to the conductive electrolyte salt, generally LIPF6, and the polymer Rrn Lnn / zznz / E / YiAi binder, generally polyvinylidene fluoride (PVDF). This is achieved first by treating waste batteries with an aqueous calcium hydroxide solution (slaked lime) to hydrolyze the conductive salt and precipitate the fluoride as calcium fluoride. Starting with conversion experiments with model substances such as LiCoOs, JP 2012-229481 discloses a process for the recovery of metals from spent lithium-ion batteries comprising a preliminary immersion stage followed by high-temperature oxidation, reductive roasting, aqueous treatment with filtration, and recovery of lithium carbonate from the filtrate and transition metals from the residue. Known methods for recovering valuable materials generally face the problem that spent batteries, and their cells which contain most of these materials, contain a high level of impurities, such as fluorine and / or phosphorus compounds, which must be removed to recover the desired materials at a purity suitable for use in the production of new cells (battery-grade materials). Therefore, one object of the present invention is to provide a process that enables the easy recovery of valuable metals contained in battery slag, namely lithium, nickel, and, if present, cobalt and / or manganese. Another object of the present invention is to provide a method for recovering other elements, such as carbon, as graphite and fluoride. A further object of the present invention is to provide an economical process that reduces the number of costly and / or energy-intensive steps.Another object of the present invention is to provide a process for the recovery of such transition metals or their compounds at high purity, especially those with low copper and noble metal content, such as silver, gold, and platinum group metals, and high-purity lithium or a lithium compound with low fluorine and / or phosphorus content or other metal impurities. In general, the recovered metals or metal compounds are transformed into the corresponding transition metal salts, often lithium sulfates and carbonates, and often lithium hydroxide. Known methods for fluoride bonding are generally complex and require several process steps. Therefore, an object of the present invention is to solve the aforementioned problems related to the recovery of Ni, Co, and lithium hydroxide from at least partially reduced black masses containing Ni and / or Co, where at least 10% of the Ni and / or Co is present in an oxidation state lower than +2 and which also contains lithium salts and fluoride salts, with the molar ratio of calcium to fluorine limited to 1.7 or less, or zero. Such black mass is often ferromagnetic. Consequently, the process as defined at the outset has been discovered, hereinafter also referred to as the inventive process or the inventive recycling process. The inventive process comprises stages defined in more detail below, hereinafter also referred to as stage (a), stage (b), stage (c), etc. Therefore, the invention relates primarily to a process for the recovery of lithium and Li salts from a material comprising waste lithium-ion batteries or parts thereof, the process comprising the steps of (a) providing a particulate material containing a transition metal compound and / or a Rrn ίηη / ζζηζ / E / γίΛΐ transition metal, wherein the transition metal is selected from the group consisting of Mn, Ni and Co, and wherein, in addition, at least a fraction of said Ni and / or Co, if present, is in an oxidation state less than +2 and at least a fraction of said Mn, if present, is manganese(II) oxide; wherein the particulate material further contains a lithium salt and a fluoride salt, and wherein the particulate material optionally contains calcium provided that the element ratio between calcium and fluorine (i.e., molar ratio: mol Ca:mol F) is 1.7 or less or zero; (b) treat the material provided in step (a) with a polar solvent and an alkaline earth hydroxide; and (c) separate the solids from the liquid, optionally followed by washing the solid residue with a polar solvent, such as water. The polar solvent used in this process is generally selected from water, alcohols, ketones, esters, organic carbonates, polyethers, nitriles, and mixtures thereof that are capable of dissolving calcium hydroxide as well as, or even better than, water. Examples of such solvents include polyols such as glycol, glycerol, and polyethylene glycols, and mixtures thereof. Protic solvents, as specifically mentioned below, are water, alcohols, and mixtures thereof. An aqueous medium, such as an aqueous solvent or aqueous liquid, contains mainly (i.e., 50% by weight or more, especially 80% by weight or more, and especially 90% by weight or more) water, including water and mixtures of water with one or more alcohols; it may contain other dissolved substances as long as the majority of the water content remains within one or more of the ranges provided above. Step (b) primarily provides a suspension of the particulate material in the polar solvent; it is preferably carried out with heating; the treatment with the alkaline earth hydroxide is generally performed at temperatures in the range of 60 to 200°C, preferably 70 to 150°C. When the boiling point of the polar solvent is exceeded, the treatment is carried out under pressure to maintain the solvent, or at least a fraction thereof, in a liquid state. Of particular technical importance is the temperature range around the boiling point of water, i.e., 70 to 150°C, where the treatment can be achieved by using an aqueous liquid or water at normal or slightly elevated pressure (e.g., up to 5 bar). Alternatively, this step (b) can be carried out with the application of higher pressures and temperatures, e.g., 150 to 300°C and 1.5 to 100 bar. The treatment is generally carried out by combining a quantity of alkaline earth hydroxide (AEH) with the particulate matter (PM), corresponding to at least 5% and, in general, no more than 100% of its weight; for example, 50–1000 g of AEH in 1 kg of PM, preferably 100–1000 g of AEH, and more preferably 200–1000 g of AEH in 1 kg of PM. The quantity of polar solvent is generally chosen to ensure miscibility of the components; for example, using 0.5 to 95 parts by weight of the combined solids (PM and AEH), preferably around 2.5 to 21 parts by weight of the polar solvent; or in certain cases, from 1 to 20 parts by weight, such as around 2 to 10 parts by weight of the polar solvent. Rrn Lnn / zznz / E / YiAi In one embodiment of the present invention, step (b) is carried out in a container that is protected against strong bases, for example, molybdenum-copper-rich steel alloys, nickel-based alloys, duplex stainless steel, or steel coated with glass, enamel, or titanium. Additional examples include polymer coatings and polymer containers made from base-resistant polymers, for example, polyethylenes such as HDPE and UHMPE, fluorinated polyethylene, perfluoroalkoxyalkanes (“PFAs”), polytetrafluoroethylene (“PTE”), PVdF, and FEP. FEP stands for fluorinated ethylene propylene polymer, a copolymer of tetrafluoroethylene and hexafluoropropylene. The treatment is generally carried out using a mixing device, for example, an agitator, with a power application typically up to 10 W per kg of suspension, e.g., from 0.5 to 10 W / kg, and / or is circulated by pumping to achieve good mixing and to prevent insoluble components from settling. Shearing can be further enhanced by using baffles. In addition, the suspension obtained in step (b) can advantageously undergo grinding treatment, e.g., in a ball mill or a stirred ball mill; such grinding treatment can lead to improved access of the polar solvent to a particulate lithium-containing transition metal oxide material. The shearing and grinding devices used are generally sufficiently corrosion-resistant; they can be manufactured from similar materials and coatings as described above for the vessel. In one embodiment of the present invention, step (b) has a duration in the range of 20 minutes to 24 hours, preferably from 1 to 10 hours. In one embodiment, step (b) is performed at least twice to achieve optimal recovery of lithium hydroxide or the lithium salt. Between each treatment, a solid-liquid separation is carried out. The resulting lithium salt solutions can be combined or treated separately to recover the solid lithium salts. In one embodiment of the present invention, steps (b) and (c) are carried out in a batch mode. In one embodiment of the present invention, steps (b) and (c) are carried out in continuous mode, for example, in a cascade of stirred vessels (step b) and / or in a cascade of stirred vessels plus centrifuge (step c). In one embodiment of the present invention, the polar solvent of present step (b) is an aqueous medium and the ratio of the aqueous medium to the material provided in step (a) is in the range of 1:1 to 99:1, preferably 5:1 to 20:1 by weight. The alkaline earth hydroxide is generally selected from the hydroxides of Mg, Ca, Sr, and Ba; calcium hydroxide, barium hydroxide, and mixtures thereof are preferred; calcium hydroxide is given the highest preference. The alkaline earth hydroxide used in this step (b) may be used as is or may be added in the form of an oxide, or a mixture of oxide and hydroxide, to form the alkaline earth hydroxide upon contact with a polar solvent selected from the protic solvents indicated above. The particulate material provided in step (a) generally comprises material obtained from waste lithium-ion batteries after carrying out the preliminary step (i) of heating under inert or reducing conditions to a temperature in the range of 80 to 900°C, for example, from 200 to 850°C, especially from 200 to 800°C. The preliminary step (i) is generally carried out directly after the discharge, dismantling, and / or shredding of the lithium-ion batteries, as explained in more detail below. In some applications, shredding and / or dismantling is carried out after the preliminary step (i). The used lithium-ion batteries, and therefore the particulate material provided in step (a), generally contain carbon, for example, in the form of graphite. Where high temperatures are indicated, for example, for treating the material present in stage (i), the exposure times, where indicated, define the total residence time in the reactor or furnace, which was heated to that high temperature; the temperature of the material must reach a temperature within the range provided for at least a fraction of that residence time. Unless otherwise specified, “contain” with respect to any substance generally means the presence of that substance in an amount usually still detectable by powder X-ray diffraction, for example, 1% by weight or more, or means the presence of such constituents in an amount usually detectable by ICP after suitable digestion, for example, 10 ppm by weight or more. The particulate matter (PM) provided in this step (a) generally contains, with respect to the elements, about 1 to 10% lithium, about 3 to 30% of the combined cobalt and / or nickel transition metal elements, and about 4 to 40% of total transition metal elements, including any cobalt, nickel, manganese, copper, and iron (all weight percentages of dry particulate matter are provided in step (a)). PM preferably contains nickel and other optional transition metals, such as Co. The particulate material provided in step (a), as well as the material subjected to step (i), will then be alternatively summarized as a lithium-containing transition metal oxide material. The carbon content can be used in the reducing pretreatment described above as a reducing agent. Other reducing agents useful for providing a reducing gas stream for this preliminary step (i) are as described in JP2012229481; preferably hydrogen and / or carbon monoxide. Therefore, the invention includes a process comprising steps (i) and (a), (b), and (c) as described above, wherein the heating step (i) is carried out under reducing conditions comprising the presence of carbon and / or a reducing gas selected from hydrogen, methane, and carbon monoxide. Stage (i) Method 1: Where hydrogen is used as a reducing gas, the preliminary step (i) is preferably carried out as follows: (i) heating a lithium-containing transition metal oxide material, which arises from lithium-ion batteries and contains fluorine compounds and / or phosphorus compounds Rrn Lnn / zznz / E / YiAi as impurities, up to a temperature in the range of 200 to 900°C, or as indicated above, in the presence of H2. In general, the heated lithium-containing transition metal oxide material in step (i) comes from lithium-ion batteries and contains fluorine preferably in the range of 1% to 8% by weight and / or phosphorus in the range of 0.2% to 2% by weight relative to the weight of the lithium-containing transition metal oxide material. Step (i) carried out with hydrogen involves heating the lithium-containing transition metal oxide material to a temperature in the range of 200 to 900°C, preferably 300 to 600°C, and more preferably 350 to 500°C. Because strong heating, especially under oxidative conditions, but to a lesser extent also in a reducing atmosphere, tends to increase the formation of insoluble species (such as LiMnO2), it is generally preferred not to expose the lithium-containing transition metal oxide material to temperatures of 500°C or higher. Consequently, it is preferred to keep the temperature in step (i) below 500°C as well. In one embodiment of the present process, step (i) is carried out using hydrogen at a temperature in the range of 350 to 450°C, for example, 380 to 450°C, and more specifically, 380 to 440°C. The atmosphere used for reduction, according to the present embodiment, contains 0.1% to 100% by volume of hydrogen, and the remainder is a non-oxidizing gas, preferably nitrogen, argon, steam, carbon monoxide, carbon dioxide, or mixtures of at least two of these gases. The preferred non-oxidizing gases are nitrogen and steam, and mixtures of nitrogen and steam. In a preferred embodiment, step (i) of the present process is carried out primarily in hydrogen, for example, in an atmosphere containing 35% to 100%, preferably 50% to 100% by volume (standard conditions) of hydrogen, and the remainder, if present, is a non-oxidizing gas. In this embodiment of the present invention, step (i) has a duration (dwell time) in the range of 10 minutes to 30 hours, preferably 20 minutes to 8 hours, more preferably 30 minutes to 4 hours. A duration of step (i) of 20 to 90 minutes, preferably with hydrogen present, is of particular technical interest. The hydrogen concentration in the reduction atmosphere and the reaction time are interdependent. Generally, a low hydrogen concentration requires longer reduction times, and vice versa. In a preferred process of the invention, step (i) is carried out by heating the lithium-containing transition metal oxide material to a temperature in the range of 350 to 450°C in the presence of more than 35%, especially 50-100% by volume, of H2 for a period of 20 to 90 minutes. Within the present invention, a particularly preferred process performs step (i) by using a temperature between 400 and 450°C, for example, between 400 and 420°C, for up to 2.5 hours and 35% or more by volume of hydrogen to recover Li in step (b) particularly efficiently. The application of excessively high temperatures may result in lower yields; the longer duration does not lead to a negative effect but tends to decrease the spatiotemporal yield, while the H2 concentrations of ≥35% by volume translate Rrn Lnn / zznz / E / YiAi in short reaction times <2.5 hy, therefore, are favored; an optimal spatiotemporal yield can be achieved by using more than 80% by volume of hydrogen. After heat treatment, the material is transferred from the furnace to a cooling unit. Here, the material is cooled to temperatures preferably of 100°C and below. Cooling can be carried out under ambient conditions, for example, by storing the hot material in a chamber or vessel, or in a rotating tube, which may be the cooled or unheated end section of a rotary kiln where the heat treatment is performed in such a way that the heat can be conducted to the surroundings. Preferably, the hot material can be cooled and conveyed by cooled conveyor screws. Faster cooling can be achieved by introducing gases which, after passing through the bed of hot material, can be fed to a heat exchanger. Such gas cooling can be designed as a fixed, moving, or fluidized bed. The gases used are preferably inert gases, such as nitrogen, argon, or carbon dioxide.It is also possible to use reducing gases for the reduction process, preferably during the initial cooling period when the material is still close to the furnace temperature. The gas composition can then be changed to an inert gas at lower temperatures; gases containing oxygen, such as air or mixtures of air and inert gases, can even be used. Alternatively, for cooling under dry conditions in a gas atmosphere, it is also possible to inactivate the heated material using a liquid. This can be accomplished by spraying the cooling liquid onto the heated material in quantities where the liquid evaporates and the material remains virtually dry (evaporative cooling) or in larger quantities where a suspension of the material is formed. Cooling with a liquid is particularly preferred when the resulting suspension or cooled material can be used directly in step (b) of this invention. Therefore, the preferred inactivating liquids are polar solvents that are sufficiently temperature-stable, with water being the most preferred. The liquid can be pumped to a heat exchanger and recirculated to the cooling vessel. Stage (i) Method 2: Where a carbonaceous material, such as carbon, is used as a reducing agent, the preliminary step (i) is preferably carried out as follows: (i) heating the lithium-containing transition metal oxide material to a temperature in the range of 200 to 900°C in the presence of said carbonaceous material, such as carbon; for example, in the presence of graphite. In a preferred embodiment of the present invention, the graphite contained in the black mass is used as a reducing agent. Typically, the heated lithium-containing transition metal oxide material in stage (i) comes from lithium-ion batteries and may contain typical impurities, such as fluorine, as explained in more detail below. Step (i) performed with carbonic material, such as carbon, as a reducing agent includes heating the lithium-containing transition metal oxide material to a temperature in the range of 200 to 900°C, preferably 300 to 850°C, more preferably 500 to 850°C. «rn Lnn / zznz / E / YiAi The atmosphere used for reduction, according to the present embodiment, contains no oxygen or up to 20% oxygen by volume, with the remainder being a non-oxidizing gas, preferably nitrogen, argon, steam, carbon monoxide, carbon dioxide, or mixtures of at least two of these gases. The preferred non-oxidizing gases are nitrogen and carbon monoxide, and mixtures of nitrogen and carbon monoxide. In a preferred embodiment, step (i) of the present process is carried out with air or diluted air, for example, under an atmosphere containing 1 to 20%, preferably 1 to 10% by volume (normal conditions), of oxygen, with the remainder, if present, being a non-oxidizing gas. In this embodiment of the present invention, step (i) lasts from 10 minutes to 30 hours, preferably from 20 minutes to 8 hours, and more preferably from 30 minutes to 4 hours.Of particular technical interest is a stage (i) duration of 20 to 120 minutes, especially 30-120 minutes, preferably with the presence of carbon. After heat treatment, the material is transferred from the furnace to a cooling unit. Here, the material is cooled to temperatures preferably of 100°C and below. Cooling can be carried out under ambient conditions, for example, by storing the hot material in a chamber or vessel, or in a rotating tube, which may be the cooled or unheated end section of a rotary kiln where the heat treatment is performed in such a way that the heat can be conducted to the surroundings. Preferably, the hot material can be cooled and conveyed by cooled conveyor screws. Faster cooling can be achieved by introducing gases which, after passing through the bed of hot material, can be fed to a heat exchanger. Such gas cooling can be designed as a fixed, moving, or fluidized bed. The gases used are preferably inert gases, such as nitrogen, argon, or carbon dioxide.It is also possible to use reducing gases for the reduction process, preferably during the initial cooling period when the material is still close to the furnace temperature. The gas composition can then be changed to an inert gas at lower temperatures; gases containing oxygen, such as air or mixtures of air and inert gases, can even be used. Alternatively, for cooling under dry conditions in a gas atmosphere, it is also possible to inactivate the heated material using a liquid. This can be accomplished by spraying the cooling liquid onto the heated material in quantities where the liquid evaporates and the material remains virtually dry (evaporative cooling) or in larger quantities where a suspension of the material is formed. Cooling with a liquid is particularly preferred when the resulting suspension or cooled material can be used directly in step (b) of this invention. Therefore, the preferred inactivating liquids are polar solvents that are sufficiently temperature-stable, with water being the most preferred. The liquid can be pumped to a heat exchanger and recirculated to the cooling vessel. In one embodiment of the present invention, the reducing conditions related to the hydrogen and / or carbon / oxygen concentration, and the temperature and duration of step (i) are selected such that at least a portion of the lithium-containing transition metal oxide material contains para-, antiferro-, ferro-, and / or ferrimagnetic components. The formation of Rrn Lnn / zznz / E / YiAi ferromagnetic or ferrimagnetic components resulting from at least partial reduction of the lithium-containing transition metal material. The extent of reduction may vary in the range of 1 to 100% with respect to the nickel content in the lithium-containing transition metal material; a range of 80 to 100% is preferred. The particulate material provided in the present step (a), therefore, contains a transition metal compound and / or a transition metal, wherein the transition metal is selected from the group consisting of Mn, Ni and / or Co, and wherein, furthermore, at least a fraction of said Ni and / or Co, if present, is in an oxidation state less than +2 and at least a fraction of said Mn, if present, is manganese(II) oxide; the nickel and / or cobalt therein are generally present, at least in part, in their metallic state. The presence of phases such as Ni and / or Co in oxidation states less than +2, Mn in the form of manganese(II) oxide and nickel and / or cobalt as metal, can be detected by XRD as described in more detail below. The lithium salt and fluoride salt present in the particulate material provided in step (a) are detected using standard methods, as described below. The lithium salt and fluoride salt contained in the particulate material provided in step (a) generally comprise one or more salts of LiOH, LiF, Li₂O, Li₂CO₃, LiHCO₃, lithium aluminate, lithium phosphate salts, mixed oxides of Li, and one or more of Ni, Co, Mn, Fe, Al, Cu, and / or fluorides of Ni, Co, Mn, Fe, Al, Cu. LiOH, LiF, Li₂O, Li₂CO₃, LiHCO₃, lithium aluminates, and lithium phosphates generally constitute 95% by weight or more of all the lithium salts present. LiF, Li₂CO₃, LiOH, and lithium aluminate are frequently present. Typically, a larger fraction of fluoride is present as lithium fluoride, for example, 50% by weight or more.Since the fluoride salt present usually arises in part from the electrolyte salt of the previous battery and the polymeric binder, which releases hydrogen fluoride during the preliminary stages of discharging, dismantling, or drying of the battery materials, other species of fluoride salts resulting from the rapid reaction of hydrogen fluoride with electrode materials or previous cells, such as cobalt fluoride, may also be present. The particulate material provided in this step (a) is generally derived from lithium-ion batteries or lithium-ion battery components, particularly the cell materials. For this step (a), it is provided as a dry powder, a wet powder, or a suspension of particles in a liquid. The material typically has an average particle diameter (D50 according to ISO 13320 EN:2009-10) in the range of approximately 1 µm to 2 mm, especially from 1 µm to 1 mm. In a typical process, the upper limit of the particle size in the powdered material is established by a sieving step performed before this step (a) or even before step (i), for example, by using a sieve with a mesh size that allows particles of up to 2 mm, and especially up to 1 mm, to pass through. In general, this lithium-containing transition metal oxide material is obtained after the mechanical removal of the casing, wiring, or circuitry, usually consisting primarily of the cell material. For safety reasons, such lithium-ion batteries are Rrn Lnn / zznz / E / YiAi batteries are completely discharged, for example, by immersion in a dry conductive bath, such as metal pulverizing, or at least 80% (preferably more than 90%, with maximum preference more than 95%) is electrically discharged so that residual electrical energy can be recovered; otherwise, electrical discharges may occur, posing a risk of fire and explosion. Such lithium-ion batteries can be disassembled, drilled, ground, for example, in a hammer mill, or crushed, for example, in an industrial crusher. Although not preferred, it is also possible to discharge the batteries by immersion in a conductive liquid, for example, an aqueous solution of a metal salt such as sodium sulfate or similar. Crushing in a liquid, preferably water, is also possible. This has the advantage of preventing dust formation and the creation of flammable atmospheres. It may be advantageous to at least partially remove the electrolytes before subjecting the material to the preliminary step (i), especially electrolytes comprising an organic solvent or a mixture of organic solvents, for example, by drying at temperatures in the range of 50 to 250°C at or below atmospheric pressure. As stated above, the lithium-containing transition metal oxide material is preferably not exposed to higher temperatures (especially 400°C or above) under oxidizing conditions before subjecting it to the present step (a). In one embodiment of the present invention, the lithium-containing transition metal oxide material is derived from battery slag. In a preferred embodiment of the present invention, the lithium-containing transition metal oxide material is derived from mechanically treated battery slag, for example, battery slag processed in a hammer mill or an industrial crusher. This mechanical processing can be carried out under dry or wet conditions, preferably in the presence of water. In one embodiment of the present invention, a step (a1) is performed prior to step (a), wherein said step (a1) comprises the removal of, for example, carbon or organic polymers by a solid-solid separation method. Examples of such solid-solid separation methods include electroseparation, sieving, magnetic separation, flotation, or other methods. The solid-solid separation may be performed dry or in the presence of a suitable dispersion medium, preferably water. In one embodiment of the present invention, the mechanically treated battery slag is ground prior to step (a). This grinding is preferably carried out in ball mills or agitated ball mills. The grinding can be performed under wet or dry conditions, preferably under dry conditions. In one embodiment of the present invention, mechanically treated battery slag is brought into contact with water and / or an organic solvent followed by a solid-liquid separation step before step (a). In one embodiment, mechanically treated battery slag is brought into contact with a basic or acidic solution to facilitate the separation of the active material from the electrode sheets, as described in WO2018192122. Rrn Lnn / zznz / E / YiAi In one embodiment of the present invention, mechanically treated battery slag is subjected to solvent treatment prior to the heat treatment of step (i) to dissolve and separate the polymeric binders used to bond the lithium transition metal oxides to the current-collecting films. Suitable solvents include N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-ethylpyrrolidone, dimethyl sulfoxide, hexamethyl phosphoramide, tetramethylurea, trimethyl phosphate, and triethyl phosphate, either in pure form or as mixtures. The solvent treatments described above can be carried out with one or more solvents in consecutive stages or in a single stage using a solvent capable of dissolving both electrolyte components and binder polymers. The solvents are applied at temperatures ranging from 10°C to 200°C. In particular, polymer dissolution may require elevated temperatures in the range of 50 to 200°C, preferably between 100 and 150°C. The upper temperature is generally limited by the solvent's boiling point, unless pressures above 1 bar are applied. In one embodiment, the washing of mechanically treated battery slag is carried out with non-protic solvents in the absence of moisture, for example, in dry gases such as dry air, dry nitrogen. In one embodiment of the present invention, the lithium-containing transition metal oxide material not only contains battery slag material but also parts or materials from parts of a lithium-ion battery, such as an off-specification material including a pure electrode material. However, the lithium-containing transition metal oxide material preferably contains, in the range of 0.1 to 80% by weight, compounds other than nickel compounds, such as nickel / cobalt components or nickel / cobalt / manganese compounds or nickel / cobalt / aluminum compounds, as applicable, and in extreme cases, the valuable material is a minor component. Examples of such components are carbon in an electrically conductive form, hereinafter also referred to as conductive carbon, for example, graphite, soot, and graphene.Other examples of impurities include copper and its compounds, aluminum and aluminum compounds (e.g., alumina), iron and iron compounds, zinc and zinc compounds, silicon and silicon compounds (e.g., silica and silicon oxides with zero and <2), tin, silicon-tin alloys, and organic polymers such as polyethylene, polypropylene, and fluorinated polymers (e.g., polyvinylidene fluoride, tetrafluoroethylene polymers, and the like). Additional impurities include fluorine compounds (e.g., inorganic fluorides) and phosphorus compounds, which can originate from liquid electrolytes (e.g., in the widely used LiPFe) and products from the hydrolysis of LiPFs.The battery slag that serves as the starting material for the inventive process can be derived from various sources, and therefore, said lithium-containing transition metal oxide material in most embodiments contains compounds that are not nickel / cobalt compounds or nickel / cobalt / manganese or nickel / cobalt / aluminum components, if applicable, where one of such components is carbon in an electrically conductive form in the range of 2 to 65% by weight, relative to the total material. Rrn Lnn / zznz / E / YiAi lithium-containing transition metal oxide. In a typical embodiment of the present invention, said lithium-containing transition metal oxide material contains one or more of the following additional components or impurities: i) in the range of 20 ppm to 10%, especially from 20 ppm to 3% by weight of copper, as metal or in the form of one or more of its compounds; i) in the range of 100 ppm to 15% by weight of aluminum, as metal or in the form of one or more of its compounds; iii) in the range of 100 ppm to 5% by weight of iron, as metal or alloy or in the form of one or more of its compounds; iv) in the range of 20 ppm to 2% by weight of zinc, as a metal or alloy or in the form of one or more of its compounds; (v) in the range of 20 ppm to 2% by weight of zirconium, as a metal or alloy or in the form of one or more of its compounds; vi) in the range of 1% to 8%, especially 2% to 8% by weight of fluorine, calculated as a sum of organic fluorine, for example, bonded to polymers and inorganic fluoride in one or more of its inorganic fluorides; vii) in the range of 0.2% to 2% by weight of phosphorus, which may occur in one or more inorganic compounds; viii) in the range of 100 ppm to 15% by weight of manganese, as a metal or in the form of one or more of its compounds. Examples of such embodiments are a lithium-containing transition metal oxide material containing one or two of the above additional components or additional components (i), (ii) and (iii); (i), (ii) and (iv); (i), (ii) and (v); (i), (ii) and (vi); (i), (ii) and (viii); (i), (iii) and (iv); (i), (iii) and (v); (i), (iii) and (vi); (ii), (ii) and (vii); (i), (iii) and (viii); (i), (iv) and (v); (i), (iv) and (vi); (i), (iv) and (vii); (i), (iv) and (viii); (i), (v) and (viiii); (i), (v) and (viiii); (i), (v) and (viiii); (i), (v) and (viiii); (i), (vi) and (vii); (i), (vi) and (viii); (i), (i), (ii) and (iv); (i), (ii), (ii) and (v); (i), (ii), (iii) and (vi); (i), (i), (iii) and (vii); (i), (i), (iii) and (viii); (i), (i), (iv) and (v); (i), (ii), (iv) and (vi); (i), (i), (iv) and (vii); (i), (i), (v) and (viii); (i), (i), (v) and (vi); (i), (i), (v) and (vii); (i), (i), (v) and (viii); (i), (ii), (vi) and (vii); (i), (ii), (vi) and (viii); (i), (i), (vii) and (viii); (i), (ii), (iv) and (v);(i), (ii), (iv) and (vi); (i), (ii), (iv) and (vii); (i), (ii), (iv) and (viii); (i), (ii), (v) and (vi); (i), (iii), (v) and (v¡¡); (i), (iii), (v) and (viii); (i), (iii), (vi) and (vii); (i), (ii), (vi) and (viii); (i), (iii), (vii) and (viii); (i), (iv), (v) and (vi); (i), (iv), (v) and (vii); (i), (iv), (v) and (viii); (i), (iv), (vi) and (vii); (i), (iv), (vi) and (viii); (i), (iv), (vii) and (viii); (i), (v), (vi) and (vii); (i), (v), (vi) and (viii); (i), (v), (vii) and (viii); (i), (vi), (vii) and (viii); (ii), (iii), (iv) and (v); (ii), (iii), (iv) and (vi); (ii), (iii), (iv) and (vii); (ii), (iii), (iv) and (viii); (ii), (iii), (v) and (vi); (ii), (iii), (v) and (vii); (ii), (ii), (v) and (viii); (ii), (iii), (vi) and (vii); (ii), (iii), (vi) and (viii); (ii), (ii), (vii) and (viii); (ii), (iv), (v) and (vi); (ii), (iv), (v) and (vii); (ii), (iv), (v) and (viii); (ii), (iv), (vi) and (vii); (ii), (iv), (vi) and (viii); (i), (iv), (vii) and (viii); (i), (v), (vi) and (vii); (ii), (v), (vi) and (viii); (ii), (v), (vii) and (viii);(ii), (vi), (vii) AND (v¡¡); (ü), (v), (v), and (vi); (iii), (iv), (v) and (vii): (iii), (iv), (v) and (viii); (iii), (iv), (vi) and (vii); (iii), (iv), (vi) and (viii); (iii), (iv), (vii) and (viii); (iii), (v), (vi) and (vii); (iii), (v), (vi) and (viii); (iii), (v), (vii) and (viii); (iii), (vi), (vii) and (viii); (iv), (v), (vi) AND (v¡¡); (v), (v), (vi) and (viii); (iv), (v), (vii) and (viii); (iv), (vi), (vii) and (viii); (v), (vi), (vii) and (viii); (i), (ii), (iii), (iv) and (v); (i), (ii), (iii), (iv) and (vi); (i), (ii), (iii), (iv) and (vii); (i), (ii), (iii), (iv) and (viii); (i), (ii), (ii), (v) and (vi); (i), (ii), (iii), (v) y; Rrn ίηη / ζζηζ / Ε / γίΛΐ (vii); (i), (i), (iii), (v) and (viii); (i), (i), (iii), (vi) and (vii); (i), (i), (ii), (vi) and (viii); (i), (i), (iii), (vii) and (viii); (i), (¡i), (iv), (v) and (vi); (i), (ii), (iv), (v) and (vii); (i), (ii), (iv), (v) and (viii); (i), (¡i), (iv), (vi) and (vii); (i), (¡i), (iv), (vi) and (viii); (i), (¡i), (iv), (vii) and (viii); (i), (i), (v), (vi) and (vii); (i), (i), (v), (vi) and (viii); (i), (i), (v), (vii) and (viii); (i), (i), (vi), (vii) and (viii); (¡)- (i), (iv), (v) and (vi); (i), (ii), (iv), (v) and (vii); (i), (ii), (iv), (v) and (viii); (i), (ii), (iv), (vi) and (vii); (i), (ii), (iv), (vi) and (viii); (i), (ii), (iv), (vii) and (viii); (i), (ii), (v), (vi) and (vii); (i), (ii), (v), (vi) and (viii); (i), (ii), (vi), (vii) and (viii); (i), (iv), (v), (vi) and (vii); (i), (iv), (v), (vi) and (viii); (i), (iv), (v), (vii) and (viii); (i), (iv), (vi), (vii) and (viii); (i), (v), (vi), (vii) and (viii); (ii), (ii), (iv), (v) and (vi); (ii), (ii), (iv), (v) and (vii);(ii), (ii), (iv), (v) and (viii); (ii), (ii), (iv), (vi) and (vii); (ii), (ii), (iv), (vi) and (viii); (i), (ii), (iv), (vii) and (viii); (ii), (iii), (v), (vi) and (vii); (ii), (iii), (v), (vi) and (viii); (ii), (iii), (v), (vii) and (viii); (ii), (i), (v), (v), and (viii); (¡i), (iv), (v), (vi) and (vii); (¡i), (iv), (v), (vi) and (viii); (¡i), (iv), (v), (vii) and (viii); (¡i), (iv), (vi), (vii) and (viii); (ii), (v), (vi), (vii) and (viii); (iii), (iv), (v), (vi) and (vii); (iii), (iv), (v), (vi) and (viii); (iii), (iv), (v), (vii) and (viii); (iii), (¡v), (vi), (vii) and (viii); (¡ii), (v), (vi), (vii) and (viii); (iv), (v), (vi), (vii) and (viii); (i), (ii), (iii), (iv), (v) and (vi); (i), (ii), (iii), (iv), (v) and (vii); (i), (ii), (iii), (iv), (v) and (viii); (i), (ii), (iii), (iv), (vi) and (vii); (i), (ii), (iii), (iv), (vi) and (viii); (i), (ii), (iii), (iv), (vii) and (viii); (i), (¡i), (iii), (v), (vi) and (vii); (i), (ii), (ii), (v), (vi) and (viii); (i), (i), (ii), (v), (vii) and (viii);(i), (i), (ii), (vi), (vii) and (viii); (i), (ii), (iv), (v), (vi) and (vii); (i), (ii), (iv), (v), (vi) and (viii); (i), (ii), (iv), (v), (vii) and (viii); (i), (¡i), (iv), (vi), (vii) and (viii); (i), (ii), (v), (vi), (vii) and (viii); (i), (iii), (iv), (v), (vi) and (vii); (i), (iii), (iv), (v), (vi) and (viii); (i), (iii), (¡v), (v), (vii) and (viii); (i), (iii), (iv), (vi), (vii) and (viii); (i), (iii), (v), (vi), (vii) and (viii); (i), (iv), (v), (vi), (vii) and (viii); (ii), (ii), (v), (v), (vi) and (vii); (ii), (iii), (iv), (v), (vi) and (viii); (ii), (iii), (iv), (v), (vii) and (viii); (ii), (iii), (iv), (vi), (vii) and (viii); (i), (i), (v), (vi), (vii) and (viii); (ii), (iv), (v), (vi), (vii) and (viii); (iii), (iv), (v), (vi), (vii) and (viii); (i), (i), (iii), (iv), (v), (v¡) and (vii); (i), (ii), (iii), (iv), (v), (vi) and (viii); (i), (i), (iii), (iv), (v), (vii) and (viii); (i), (ii), (iii), (iv), (vi), (vii) and (viii); (i), (i), (i), (v), (vi), (vii) and (viii); (i), (ii), (iv), (v), (vi), (vii) and (viii); (i), (ii), (iv), (v), (vi), (vii) and (viii); (ii), (iii), (iv), (v), (vi), (vii), and (viii). Another example is a lithium-containing transition metal oxide material that contains each of the above additional components. Each of the percentages provided above is by weight of the dry material (i.e., the lithium-containing transition metal oxide material as provided in the present step (a)). This lithium-containing transition metal oxide material generally contains nickel or cobalt, or more specifically, both nickel and cobalt. Examples of lithium-containing transition metal oxide materials include lithiated nickel cobalt manganese oxide (“NCM”) or lithiated nickel cobalt aluminum oxide (“NCA”), or mixtures thereof. Examples of layered nickel-cobalt-manganese oxides are compounds of the general formula Lii+x(NiaCobMncM1d)i xO2, where Mi is selected from Mg, Ca, Ba, Al, Ti, Zr, Zn, Mo, V, and Fe, where additional variables are defined as follows: zero < x < 0.2 0.1 < a < 0.95, Zero < b < 0.9, preferably 0.05 < b < 0.5, zero < c < 0.6, zero <d¿0.1,ya + b + c + d = 1. In a preferred embodiment, in compounds according to General Formula (I) Rrn Lnn / zznz / E / YiAi L¡(i+x)[N¡aCobMncM1d](1-x)O2 (I) M1 is selected from Ca, Mg, Zr, Al, Ti and Ba, and the additional variables are as defined above. Examples of lithiated nickel-cobalt-aluminum oxides are compounds of the general formula Li[NihCoAlj]O2+r. Typical values ​​for r, h, i, and j are: h is in the range of 0.8 to 0.95, i is in the range of 0.02 to 0.3, j is in the range of 0.01 to 0.10, and r is in the range of zero to 0.4. Particularly preferred are L¡(i+x)[N¡o.33Coo.33Mno.33](ix)02, Li(i+x)[N¡o.5Coo.2Mno.3](ix)02, Li(i+x)[N¡o.6Coo.2Mno.2](ix)O2, L¡(i+x)[N¡o.7Coo.2Mno.i](ix)02, Li(i+x)[Nio.8Coo.iMno.i](ix)O2, where each x is as defined above, and LijNio ssCoo ΐ3ΑΙοο2]θ2. This lithium-containing transition metal oxide material can have a regular shape, but it is usually irregular. However, it is preferable to remove as much of the lighter fraction, such as organic plastic casing parts and aluminum foil or copper foil, as possible, for example, in a forced gas stream. In one embodiment, the composition of the atmosphere is changed during step (i). This can be done, for example, if there are volatile organic compounds in the feed that are separated in an inert atmosphere before changing the atmosphere to a reducing one, for example, an atmosphere containing hydrogen. In one embodiment, an oxidizing atmosphere is used at a temperature range of 20 to 300°C in step (i) prior to reduction with a hydrogen-containing atmosphere. This embodiment allows for the combustion of some impurity components, namely organic components, or the drying of the material (particularly by using temperatures up to 250°C, as previously mentioned). The preferred oxidizing gases are oxygen or oxygen-containing gases, such as air. The material from spent lithium-ion battery cells, containing lithium, a transition metal oxide, and a fluorine and / or phosphorus compound, is preferably not subjected to oxidation above 300°C before carrying out the steps of this process. In one embodiment of the present invention, a step (a1) is performed prior to step (a), wherein step (a1) comprises the removal of, for example, carbon or organic polymers by a dry solid-solid separation method. Examples of such dry solid-solid separation methods include electroseparation, sieving, magnetic separation, or methods of another classification. Herein, step (a1) is presented as an additional step. In one embodiment of the present invention, the material provided in step (a) is ground before step (b) to deagglomerate the different solid particles from each other when they are agglomerated in some way, for example, by residual binding polymers. The grinding can be carried out under dry or wet conditions. Preferably, the grinding is carried out in a medium Rrn Lnn / zznz / E / YiAi aqueous which is also used in the consecutive step (b). At the end of step (b), the pressure can be released if appropriate. A lithium salt solution is obtained, similar to the liquid in step (c), generally an aqueous solution containing LiOH. Prior to the present step (c), the solid residue is held in a polar solvent, which may be an aqueous solution, and a suspension is formed. If the extraction of the Li compounds is carried out in two or more steps as described above, the solid residue will be held in the suspension of the second or last step, respectively. The solid residue obtained in step (c) is recovered by solid-liquid separation step (c). This can be filtration, centrifugation, or a type of sedimentation and decantation, optionally with subsequent washing steps that apply the respective polar solvent used in step (b) as the washing medium. The filtrate and washing liquids are generally combined before the recovery of the lithium salts. To recover such fine particles containing solid material, for example, with an average diameter of 50 µm or less, flocculants, such as polyacrylates, can be added. The solid residue obtained according to step (c) is characterized by a typical elemental composition resulting from the application of the preferred process conditions during step (b). Specifically, the solid residue is characterized by having a composition typical of battery slag material (Li, graphite, and at least one of Ni, Co, and Mn present), but with a significantly higher weight ratio (Ni + Co + Mn) to Li. Since battery slag material, especially active cathode material, is characterized by a weight ratio (Ni + Co + Mn):Li between 5 and 12, the solid residue after step (c) is characterized by its low Li content and, therefore, by a weight ratio (Ni + Co + Mn):Li between 13 and 100,000.Furthermore, the preferred process in step (b) is accompanied by a significant increase in calcium content, which is very low in the original particulate material provided in step (a), as mentioned above (0.5% by weight). The solid residue obtained according to step (c) is characterized by an elemental Ca content between 2 and 50% (relative to the dry solid). The solid residue that can be obtained according to step (c) is a valuable source of materials useful for the production of new batteries; the steps for the isolation of such materials are described below. The solid residue obtained according to step (c) can then be subjected to step (d), a solid-solid separation for the removal of Ni and / or Co, if present. Step (d) recovers the nickel as a nickel-containing solid. Step (d) of the present invention comprises a solid-solid separation step. In a preferred embodiment, it is a wet solid-solid separation step. This solid-solid separation step serves to separate insoluble components such as carbon and polymers or insoluble inorganic components, for example, metal particles or metal oxide particles, from the metallic or metal oxide components of the lithium-containing transition metal oxide material. After the solid-solid separation of step (d), a concentrate fraction is obtained. Rrn Lnn / zznz / E / YiAi solid containing most of the Ni and, if applicable, the Co in enriched form. This solid-solid separation step can be carried out by mechanical, column, pneumatic, or hybrid flotation. In many embodiments, collector compounds are added to the suspension, making the target components hydrophobic. Typical collector compounds for polymer and carbon particles are hydrocarbons or fatty alcohols, introduced in quantities of 1 to 50 kg / t of the solid residue obtained from step (c). Flotation can also be carried out in reverse, transforming the originally hydrophilic components into strongly hydrophobic components using special collector substances, such as esterquats or fatty alcohol sulfates. Direct flotation using hydrocarbon collectors, such as mineral oils, kerosene, or diesel, is preferred.To improve the selectivity of flotation towards carbon and polymer particles, suppressant agents can be added to reduce the amounts of metallic and metal oxide components entrained in the froth phase. These agents can be acids or bases to control the pH value within a range of 3 to 9. They can also be ionic components that adsorb onto the metallic or metal oxide surface, such as bipolar compounds or sodium silicates like amino acids. To increase flotation efficiency, it can be advantageous to add carrier particles that form agglomerates with the hydrophobic target particles, such as polymer particles or carbonaceous particles like graphite or coal. By using magnetic carrier particles, magnetic agglomerates can be formed that can be separated magnetically.If the target components are para-, antiferro-, or ferrioferromagnetic, it is also possible to separate these components by magnetic separation using high-intensity magnetic separators (WHIMS), medium-intensity magnetic separators (MIMS), or low-intensity magnetic separators (LIMS). Other solid-solid separation techniques utilize the density difference of the solid constituents, for example, the density difference between graphite and metals or metal oxides. These techniques include sink-float methods that use fluids with densities intermediate to the densities of the solid components to be separated. Another technique of this type is heavy media separation. Other separation techniques based on density differences include spirals and hydrocyclones. In addition, combinations of at least two of the solid-solid separation techniques mentioned above can be used. These combinations may include scraping, sweeping, and cleaning stages, which are common in flowcharts for mineral processing. In a preferred embodiment, the solid-solid separation of stage (d) is a magnetic separation. In one embodiment of the present invention, the solid material obtained from step (c) is ground before step (d) to separate the individual solid particles from each other when they are agglomerated in some way, for example, by residual binding polymers. This grinding is preferably carried out in ball mills or agitated ball mills. In one embodiment of the present invention, step (d) is a wet solid separation using an aqueous medium, preferably water, as the fluid. The ratio of the fluid medium to the solid material in step (d) is generally in the range of 1:1 to 99:1, preferably 2:1 to 9:1 by weight. From the wet solid-solid separation of step (d), two suspensions are derived: one containing the target transition metal solid and one containing the other components, such as carbonaceous materials and polymers, and, if applicable, some inorganic compounds as well. By selecting and, if necessary, combining the appropriate solid-solid separation steps, at least 60% of the Ni and, if present, the Co are obtained and concentrated into a fraction. Preferably, at least 80 to 99% of the Ni and, if present, the Co are separated. In one embodiment of the present invention, the liquid phase of the suspension fed to step (d) contains dissolved lithium. In this case, one or both of the suspensions obtained from the solid-solid separation of step (d) are advantageously subjected to a solid-liquid separation to recover the lithium solution. The lithium solution can then be further treated in step (e). In step (e), the solution obtained from any of the previous steps, for example step (c) and / or step (d), which contains lithium, is treated to recover the lithium as hydroxide or salts in the form of solid materials. In one embodiment of the present invention, the L1 salts, in particular L1OH, are recovered by evaporating the water from the solution (e1). To produce the desired high-purity L1 salt, the evaporation can be carried out in two or more consecutive stages (e.g., e2 and e3). First, the solution containing LiOH from any of the previous stages is concentrated near the point where the solubility limit of LiOH is reached. This stage is accompanied by the solid formation (e.g., crystallization) of impurities with lower solubilities than LiOH; possible impurities include Ca(OH)₂, CaF₂, CaCO₃, and LIF, among others. These are separated by solid-liquid separation, for example, by filtration or centrifugation, or by sedimentation and decantation. A combination of two solid-liquid separation stages, such as a hydrocyclone followed by a depth filter, is also possible because the amount of remaining solids to be separated is small. If LIF precipitates during this first concentration stage (e2), it is preferable to feed the solid material back to stage (b). Secondly, the filtrate obtained from the solid-liquid separation after one of the concentration stages, i.e., the concentrated LiOH solution, is used in the next evaporation stage (e3). High-quality LiOH can be obtained by evaporating the remaining water and forming solid LiOH. If crystallization occurs, the crystals are separated from the remaining mother liquor, again by solid-liquid separation, and optionally washed. To concentrate impurities, several crystallization stages followed by washing and solid-liquid separation are possible. Any mother liquor obtained from crystallization can be subjected to additional stages such as evaporation, crystallization, separation (e.g., ion exchange) and / or recycling by introducing the mother liquor into stage (b) or (e1) or (e2). Rrn Lnn / zznz / E / YiAi For all the solidification stages mentioned above, subsequent drying of the solids is advantageous. Drying, either below 60°C or at higher temperatures under high humidity conditions, leads to LiOH monohydrate; otherwise, at least partially water-free LiOH is obtained. In this case, the filtrate obtained after step (c) is dried by complete evaporation of the polar solvent, for example, water, according to step (e1) described, yielding a LiOH (anhydride or monohydrate) that is of high purity (>98.5%). It contains an impurity spectrum that is characteristic of the process described above, for example, carbon-based impurities of less than 0.35% by weight. With reference to LiOH monohydrate, the characteristic impurities are calcium, fluorine, and sodium. The typical amounts within this LiOH monohydrate are: Ca: 100 ppm - 1.29% by weight F: 0.1 - 1.29% by weight Na: 0.1 - 1.29% by weight Furthermore, depending on the composition of the PM, significant amounts of zinc, aluminum, potassium, and chlorine may be present. In these cases, the characteristic amounts in a LiOH monohydrate described above, obtained after step (e1), are within the following ranges: Zn: 20 ppm - 1.29% by weight Al: 50 ppm - 1.29% by weight K: 0.1 - 1.29% by weight Cl 0.1 - 1.29% by weight Depending on the drying conditions, anhydrous LiOH is obtained instead of the monohydrate. In this case, the characteristic amounts of impurities mentioned above, which are related to the monohydrate, are more concentrated, respectively, by a factor of 1.75 (corresponding to the molar mass of the monohydrate divided by the molar mass of the anhydrate) for 100% water-free LiOH. All applied steps, including steps (b), (c), (d) and (e) are preferably carried out in an inert atmosphere, for example, nitrogen, argon or CO2-free air. In one embodiment of the present invention, L¡ is recovered from the solution obtained in step (c) by precipitation as L¡ carbonate by adding sodium carbonate or ammonium carbonate or by carbonic acid formed by dissolving carbon dioxide, preferably under pressure (step e5). In one embodiment, the Li carbonate is redissolved by the additional addition of CO2 to the solution, preferably under pressure, forming dissolved LiHCO3 (e6). Any impurities present can be removed using prior art purification techniques, such as solvent extraction, precipitation, and / or ion exchange. Following this further purification, Li carbonate can be obtained by increasing the temperature of the solution, which directly leads to the precipitation of Li carbonate (e7). Pure Li carbonate can then be obtained by subsequent solid-liquid separation. Rrn Lnn / zznz / E / YiAi In a preferred embodiment of the present invention, Li is recovered as LiOH. The solid LiOH and / or Li salts obtained can be further purified by dissolution and recrystallization as known in the art. The solid Ni concentrate obtained from step (c) or (d) can be subjected to a subsequent step (f), which allows for the extraction of Ni and, if applicable, Co and, if applicable, other valuable metals such as Zr contained in the Ni concentrate. Smelters or ammonia or acid leaching can be used for extraction. In one embodiment of the present invention, said step (f) can be pyrometallurgical by melting the solid Ni concentrate obtained in step (c) or (d) as such or as a feed together within a smelter dedicated to Ni concentrates from mining production. During the course of such step (f), the transition metal material can be treated with a leaching agent, which is preferably an acid selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, oxalic acid and citric acid or a combination of at least two of these, for example, a combination of nitric acid and hydrochloric acid. In another preferred form, the leaching agent is an inorganic acid, such as sulfuric acid, hydrochloric acid, nitric acid, an organic acid, such as methanesulfonic acid, oxalic acid, citric acid, aspartic acid, melic acid, ascorbic acid, or glycine, a base, such as ammonia, aqueous solutions of amines, ammonia, ammonium carbonate, or a mixture of ammonia and carbon dioxide, or a chelating agent, such as Na4EDTA, Na2H2EDTA, H4EDTA (in the following sections, these three chelating agents are summarized as EDTA), or dimethylglyoxime. In one embodiment, the leaching agent comprises an aqueous acid, such as an organic or inorganic aqueous acid. In another embodiment, the leaching agent comprises a base, preferably ammonia or an amine. In another embodiment, the leaching agent comprises a complexing agent, preferably a chelating agent. In yet another embodiment, the leaching agent comprises an inorganic acid, an organic acid, a base, or a chelating agent. The concentration of chelating agents can be varied over a wide range, for example, from 0.1 to 98% by weight, and preferably from 10 to 80%. The preferred example of an aqueous acid is aqueous sulfuric acid, for example, with a concentration in the range of 10 to 98% by weight. Preferably, the aqueous acid has a pH value in the range of -1 to 2. The amount of acid is adjusted to maintain an excess of acid relative to the transition metal. Preferably, at the end of step (f), the pH value of the resulting solution is in the range of -0.5 to 2.5. Preferred examples of a base as a leaching agent are aqueous ammonia with a molar ratio of NH3 to metal (Ni, Co) of 1:1 to 6:1, preferably from 2:1 to 4:1, also preferably in the presence of carbonate or sulfate ions. Suitable chelating agents such as EDTA or dimethylglyoxime are often applied in a molar ratio of 1:1 to 3:1. Leaching can be carried out in the presence of oxidizing agents. A preferred oxidizing agent Rrn Lnn / zznz / E / YiAi is oxygen as a pure gas or in mixtures with inert gases, for example, nitrogen, or as air. Other oxidizing agents are oxidizing acids, for example, nitric acid, or peroxides, such as hydrogen peroxide. In one embodiment of the present invention, said step (f) can be carried out by dissolving the solid Ni concentrate obtained in step (c) or (d) in an acid selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, oxalic acid, and citric acid. In one embodiment of the present invention, said step (f) can be carried out by treating the solid Ni concentrate obtained in step (c) or (d) with an aqueous solution of ammonium carbonate or ammonium bicarbonate. Said aqueous solution may contain additional ammonia. In one embodiment of the present invention, the Ni concentrate obtained in step (c) or (b) is treated in step (f) with an acid selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, oxalic acid, and citric acid, or a combination of at least two of these, for example, a combination of nitric acid and hydrochloric acid. In the case of aqueous acids, the acid concentration can vary over a wide range, for example, from 0.1 to 99% by weight, and preferably from 10 to 96%. The amount of acid is adjusted to maintain an acid excess. Preferably, at the end of step (f), the pH value of the resulting solution is in the range of -0.5 to 2. The preferred example of aqueous acid is aqueous sulfuric acid, for example, with a concentration in the range of 10 to 98% by weight. The treatment according to step (f) can be carried out at a temperature in the range of 20 to 200°C, especially from 20 to 130°C. If temperatures above 100°C are desired, step (f) is carried out at a pressure above 1 bar. Otherwise, normal pressure is preferred. In one embodiment of the present invention, step (f) is carried out in a container that is protected against strong acids, for example, molybdenum-copper-rich steel alloys, nickel-based alloys, duplex stainless steel, or steel coated with glass, enamel, or titanium. Additional examples include polymer coatings and polymer containers made from acid-resistant polymers, such as polyethylenes like HDPE and UHMPE, fluorinated polyethylene, perfluoroalkoxyalkanes (“PFAs”), polytetrafluoroethylene (“PTFE”), PVDF, and FEP. FEP stands for fluorinated ethylene propylene polymer, a copolymer of tetrafluoroethylene and hexafluoropropylene. The suspension obtained from step (f) can be stirred, agitated, or subjected to grinding treatment, for example, in a ball mill or a stirred ball mill. Such grinding treatment often leads to improved access of water or acid to the particulate transition metal material. In one embodiment of the present invention, step (f) lasts from 10 minutes to 10 hours, preferably from 1 to 3 hours. For example, the reaction mixture in step (f) is stirred at power levels of at least 0.1 W / L or circulated by pumping to achieve thorough mixing and to prevent insoluble components from settling. Shearing can be further enhanced by using baffles. All such shearing devices must be made of materials and coatings with sufficient corrosion resistance. Rrn ίηη / ζζηζ / Ε / γίΛΐ similar as described for the container itself. Step (f) can be carried out in an air atmosphere or in air diluted with N2. However, it is preferred that step (f) be carried out in an inert atmosphere, e.g. nitrogen or a rare gas such as Ar. Treatment according to step (f) leads to the dissolution of the metal compounds remaining after the leaching of LiOH in step (b), which include non-carbon impurities or organic polymers. In most embodiments, a suspension is obtained after carrying out step (f). Residual lithium and transition metals, such as, but not limited to, nickel, cobalt, copper, and, if applicable, manganese, are often found in dissolved form in the leach, for example, as their salts. In embodiments where a so-called oxidizing acid has been used in step (f), it is preferred to add a reducing agent to remove the unused oxidizing agent. Examples of oxidizing acids are nitric acid and combinations of nitric acid with hydrochloric acid. In the context of the present invention, hydrochloric acid, sulfuric acid, and methanesulfuric acid are preferred examples of non-oxidizing acids. In one embodiment, step (f) is carried out in an inert gas, such as nitrogen or argon. Depending on the concentration and quantity of aqueous acid used in step (f), the liquid phase obtained in step (f) can have a transition metal concentration in the range of 1 to 25 wt%, preferably 6 to 15 wt%. The transition metal concentration depends on the solubility of the corresponding salts of the acid used. Preferably, step (f) is carried out so that the transition metal concentrations of the main metals, such as Ni and, optionally, Co and Mn, are slightly below the solubility limit of the least soluble salt to ensure a high metal concentration in the solution. An optional step that can be carried out after step (f) is the removal of undissolved solids, for example, carbonaceous and polymeric materials resulting from battery casings. This step can be carried out by centrifugation, filtration, or sedimentation and decantation, with or without the addition of flocculants. The resulting solid residue can be washed with water and further treated to separate the carbonaceous and polymeric components, for example, by solid-solid separation methods as described above. In one embodiment of the present invention, step (f) and the removal of undissolved solids are carried out sequentially in a continuous operating mode. Once the Ni concentrate has been dissolved in step (f), in a subsequent step (f1), the pH value of the suspension or solution can be adjusted from 2.5 to 8, preferably from 5.5 to 7.5, and even more preferably from 6 to 7. The pH value can be determined by conventional means, for example, potentiometrically, and refers to the pH value of the continuous liquid phase at 20°C. The pH adjustment is carried out by dilution with water, by the addition of bases, or by a combination thereof. Examples of suitable bases are ammonia and alkali metal hydroxides, for example, LiOH, NaOH, or KOH, in solid form, for example, as pellets, or, preferably, as aqueous solutions. Combinations of at least two of the above are also possible, for example, combinations of ammonia and aqueous caustic soda. Preferably, an optional step (f2) comprises the removal of precipitates of carbonates, oxides, phosphates, hydroxides, or oxyhydroxides of Al, Cu, Fe, Zr, Zn, or combinations of at least two of the foregoing formed in the optional step (f1). Such precipitates may form during pH adjustment. The phosphates may be stoichiometric or basic phosphates. Without intending to be limited to any theory, phosphates may be generated during phosphate formation by the hydrolysis of hexafluorophosphate or its decomposition products formed during the pretreatment of the particulate material provided in the present step (a). Such precipitates may be removed by filtration, centrifugation, or sedimentation. Preferred filters include belt filters, filter presses, suction filters, and cross-flow filters.Filtration aids and / or flocculants can be added to improve solid-liquid separation. In a preferred embodiment of the present invention, step (f2) includes an optional step (f3). Step (f3) includes treating a solution obtained after step (f1) or step (f2) with metallic nickel, metallic cobalt, or metallic manganese, or any combination of at least two of the foregoing. In the optional step (f3), a solution obtained after step (f2) is contacted with metallic nickel, cobalt, or manganese, or a combination of at least two of the foregoing, for example, in a column. In such embodiments, it is advantageous to provide a column filled with metallic nickel, metallic cobalt, or metallic manganese, or a combination of at least two of the foregoing, in the form of lumps or granules, for example, as a fixed bed, and to allow a stream of the solution to flow through such a column. In one embodiment of the present invention, step (f3) is carried out at normal pressure. In one embodiment of the present invention, step (f3) lasts from 30 minutes to 5 hours. If step (f3) is carried out in a column, the duration corresponds to the average residence time. In one embodiment of the present invention, step (f3) is carried out with a pH value range of 1 to 6, preferably the pH is from 2 to 5. The lower the pH value in step (f3), the greater the amount of selected metal Ni, Co, and Mn to be dissolved during hydrogen formation. Step (f3) is particularly useful for removing trace amounts of copper. By carrying out step (f3), no new impurities are introduced into the transition metal solution that would require an additional purification step. Even if the nickel, cobalt, or manganese metal contains trace amounts of copper, these do not dissolve. The separation of copper in stage (f3) can also be carried out by electrolysis, preferably by using an electrochemical filter cell that uses conductive particulate material as an electrode, for example, the graphite contained in the black mass. Rrn Lnn / zznz / E / YiAi Alternatively, copper can be extracted by solvent extraction or ion exchange prior to precipitation of Al, Fe, Zr and / or Zn and can be recovered as high-grade copper by electrodeposition. From the mixed solution containing Ni, Co, and / or Mn, the individual metals can be recovered as pure metal salts according to known prior art procedures, for example, precipitation as oxides, hydroxides, carbonates, or sulfides, solvent extraction, ion exchange, or electrodeposition. These pure metal salts can then be reintroduced into the synthesis of active cathode materials, for example, according to steps (g1) and (g). An optional step (g), which is typically carried out after step (f) and optional steps (f1), (f2), (f3), includes the precipitation of the transition metals as mixed hydroxides or mixed carbonates, preferably as mixed hydroxides. In a preferred embodiment of the present invention, step (g) is carried out by adding ammonia or an organic amine, such as dimethylamide or diethylamide, preferably ammonia, and at least one inorganic base, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, or potassium bicarbonate, or a combination of at least two of the foregoing. The addition of sodium hydroxide and ammonia is preferred. In one embodiment of the present invention, step (g) is carried out at a temperature in the range of 10 to 85°C, preferably from 20 to 50°C. In one embodiment of the present invention, the concentration of the organic amine, or ammonia, is in the range of 0.05 to 1 mol / L, preferably from 0.1 to 0.7 mol / L. The term “ammonia concentration” in this context includes the concentration of ammonia and ammonium. Particular preference is given to amounts of ammonia for which the solubility of N2+ and CO2+ in the mother liquor is not greater than 1000 ppm each, more preferably not greater than 500 ppm each. In one embodiment of the present invention, the mixing is carried out during step (g) of the inventive process, for example, using a stirrer, a rotor-stator mixer, or a ball mill. It is preferred to introduce a stirring power of at least 1 W / L into the reaction mixture, preferably at least 3 W / L, and more preferably 5 W / L. In one embodiment of the present invention, a stirring power of no more than 25 W / L may be introduced into the reaction mixture. The optional step (g) of the inventive process can be carried out in the presence or absence of one or more reducing agents. Examples of suitable reducing agents include hydrazine, primary alcohols such as, but not limited to, methanol or ethanol, as well as ascorbic acid, glucose, and alkali metal sulfites. It is preferred not to use any reducing agent in step (g). The use of a reducing agent or an inert atmosphere, or both in combination, is preferred in cases where large amounts of manganese are present in the transition metal oxide material, for example, at least 3 mol% relative to the transition metal portion of the respective active cathode material. Rrn Lnn / zznz / E / YiAi Step (g) of the inventive process can be carried out in an atmosphere of an inert gas such as, for example, nitrogen, argon, or carbon dioxide. In one embodiment of the present invention, step (g) is carried out at a pH value in the range of 9 to 13.5, preferably the pH values ​​are from 11 to 12.5 for the hydroxides and the pH values ​​are in the range of 7.5 to 8.5 for the carbonates. The pH value refers to the pH value of the mother liquor, determined at 23°C. Step (g) can be carried out in a batch reactor or, preferably, continuously, for example, in a stirred tank reactor or in a cascade of two or more, for example, two or three, stirred tank reactors. Step (g) of the inventive process can be carried out in air, in an inert gas atmosphere, for example, in a nitrogen or noble gas atmosphere, or in a reducing atmosphere. An example of a reducing gas is SO2. Preference is given to working in an inert gas atmosphere, especially nitrogen gas. For the purpose of further purification, the solids recovered in step (g) can be separated and dissolved in an acid, for example, hydrochloric acid or, more preferably, sulfuric acid. By carrying out the inventive process, it is possible to recover the transition metals nickel and, if applicable, cobalt and / or manganese from cathode materials containing nickel and cobalt and, if applicable, also manganese, in a form that allows them to be readily converted into active cathode materials. In particular, the inventive process enables the recovery of transition metals such as nickel and, optionally, cobalt and / or manganese, containing only minimal, tolerable amounts of impurities such as copper, iron, and zinc, for example, with less than 10 ppm of copper, preferably even less, for example, from 1 to 5 ppm. In one embodiment of the present invention, in an additional step (g1) prior to step (g), nickel, cobalt, and / or manganese salts are added to the recycled metal salt solution from step (f) or (f1), (f2), or (f3) to adjust the metal ratio to the composition of a desired mixed metal hydroxide precipitate, which can be used as a precursor material for the production of an active cathode material. During this precipitation, additional metal salts can be added, preferably as an aqueous solution of acid anions used in step (f); an example of such a metal is aluminum, which can be added as aluminum sulfate. The mixed metal hydroxide precipitate can be separated from the liquid by solid-liquid separation and dried to obtain a dry mixed metal hydroxide precipitate with a water content of no more than 10% by weight.In this way, a precursor for active cathode material can be obtained directly in the subsequent precipitation step (g). The mixed metal hydroxide precipitate obtained in step (g) can be further treated as a dry powder with lithium salts, preferably lithium carbonate and, more preferably, lithium hydroxide. The lithium salts preferably obtained from step (e) of the present inventive process can be dry-mixed with the dry mixed metal hydroxide precipitate and subjected to a calcination process comprising a temperature range of 400 to 900°C, preferably 450 to 800°C. In this way, a lithium-containing metal oxide can be obtained. Rrn Lnn / zznz / E / YiAi mixed containing nickel and / or cobalt. In one embodiment of the present invention, the solid Ni concentrate obtained in step (d) is treated with aqueous ammonium (bi)carbonate solution at concentrations of 0.2 to 30% by weight, preferably 1 to 20% by weight. The suspension can be heated to temperatures of 30 to 150°C. At temperatures above the boiling point of the mixture, heating is carried out under pressure. Below the boiling point, applying pressure is advantageous to maintain sufficient ammonia and carbon dioxide in the system. Treatment with ammonium (bi)carbonate can be carried out in an inert atmosphere or in the presence of oxygen, for example, in air. The leachate or solution may also contain hydrogen peroxide and / or additional ammonia. Treatment with ammonium (bi)carbonate dissolves Ni and, if applicable, Co and Cu as ammonium complexes. The concentration of metal ammonium complexes in the leach liquor can range from 0.2 to 30 wt% per metal, preferably 1–15 wt%. The solution obtained by this treatment undergoes solid-liquid separation, resulting in a solution containing mostly Ni ammonium complexes and, if applicable, Co and Cu, and a separate solid residue containing mostly other transition metals, if applicable, namely Mn and Fe. The resulting solution can be heated, and the ammonia can be removed by purging with carbon dioxide. Using this initial Ni carbonate and, after a longer treatment advantageously at elevated temperatures, Co carbonate will also be obtained as a precipitate. This allows for the separation of the two metals. In one embodiment of the present invention, the Ni and Co carbonates are not separated from each other. The carbonates from the mixed Ni / Co precipitate are separated from the mother liquor and can be dissolved using sulfuric acid or other acids to obtain a solution of the corresponding Ni and, if applicable, Co salts. This solution may also contain small amounts of Cu salts, which can be removed by treatment with metallic Ni, Co, or Mn as described above. Other impurities, such as Fe or Al, which may be present in low concentrations, can be removed by precipitation of hydroxide or carbonate at pH values ​​between 2.5 to 8 as also described above. Starting from the Ni salt solution and, if applicable, purified Co and the Ni and Co hydroxides, a coprecipitation can be carried out. In one embodiment of the present invention, the solution is further treated to extract the Ni and Co salts separately, for example, by solvent extraction methods. Pure metals can then be recovered from the separated Ni and Co salts using electrochemical methods known in the prior art. In one embodiment, the precipitation of the transition metals after steps (f1), (f2), and (f3) is carried out using hydrogen at elevated temperature. For this purpose, the pH of the solution is maintained at a basic level by adding ammonia and / or ammonium carbonate. In this way, Ni, Co, and Cu can be precipitated as metals. Certain catalysts known in the prior art can be added to enhance this reaction. Description of the methods: Particle size distribution measurements, including the determination of D50, are performed in accordance with ISO 13320 EN:2009-10. Elemental analysis of lithium, calcium and manganese (carried out, among other things, to determine the Li, Ca, Mn content of the particulate matter provided in this stage (a)): The reagents are: Deionized water, hydrochloric acid (36%), mixture of K2CO3-Na2CO3 (dry), Na2B4O7 (dry), hydrochloric acid 50% by volume (1:1 mixture of deionized water and hydrochloric acid (36%)); all reagents are PA grade. Sample preparation: 0.2–0.25 g of the particulate material for this step (a) (usually obtained from waste lithium-ion batteries after preliminary reduction step (i)) is weighed into a Pt crucible and subjected to K2CO3-Na2CO3 / Na2B4O7 melt digestion. The mixture is burned in an open flame and then completely ashed in a muffle furnace at 600°C. The remaining ash is mixed with K2CO3-Na2CO3 / Na2B4O7 (0.8 g / 0.2 g) and melted to a clear melt. The cooled melt cake is dissolved in 30 mL of water, and 12 mL of 50% v / v hydrochloric acid is added. The solution is then brought up to a defined volume of 100 mL. This process is repeated three times independently. Additionally, a blank sample is prepared for reference purposes. Measurement: The concentrations of Li, Ca, and Mn in the solution obtained were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Instrument: Agilent 5100 SVDV ICP-OES; wavelengths: Li 670.783 nm; Ca 396.847 nm; Mn 257.610 nm; internal standard: Se 361.383 nm; dilution factors: Li 100, Ca 10, Mn 100; calibration: external. Elemental analysis of fluorine and fluoride is carried out according to standardized methods: DIN EN 14582:2016-12 regarding sample preparation for the determination of total fluoride content (waste samples); the detection method is an ion-selective electrode measurement. DIN 38405-D4-2:1985-07 (water samples; digestion of inorganic solids with acid distillation with back support and determination of fluoride using an ion-selective electrode). Other metal impurities and phosphorus are determined analogously by elemental analysis using ICP-OES (inductively coupled plasma optical emission spectroscopy) or ICP-MS (inductively coupled plasma mass spectrometry). Total carbon is determined with a thermal conductivity detector after combustion. The solid phase compositions [including the identification of manganese(II) oxide and Ni and Co in an oxidation state lower than +2 (typically metallic) in the particulate material provided in step (a)] are determined by powder X-ray diffraction (PXRD). The method is carried out as follows: Rrn Lnn / zznz / E / YiAi The sample is ground into a fine powder and loaded into the sample container. Two devices are used, each with a specific radiation source. (1) Measurement by applying Cu radiation: The instrument used is a Bruker D8 Advance from the 2 series with an automatic sampling unit; primary side: Cu anode, beam spread angle aperture 0.1° with ASS; secondary side: Dispersed beam aperture 8 mm with Ni 0.5 mm, Soller 4°, Lynx-Eye (3° aperture). (2) Measurement by applying Cu radiation: The instrument used is a Bruker D8 Discover A25 with an automatic sampling unit; primary side: Mo anode with Johansson monochromator (Mo-K-alpha1) with an axial Soller 2.5°, secondary side: ASS, Soller 2.5°, Lynx-Eye XE detector (3.77° aperture). References are used to identify matches with the obtained reflection pattern. All relevant phases are known from the literature; the following references are consulted and used to calculate the theoretical diffraction pattern (see the position and intensity of the reflections in Table 1 below): a) CoxNii-x; Fm-3m space group; x = 0.5: Taylor etal., J. Inst. Met. (1950) 77, 585-594. x = 0: Buschow et al.; J. Magn. Magn. Mater. 1983, 38, 1-22. b) Co; space group P63 / mmc; Buschow et al.; J. Magn. Magn. Mater. 1983, 38, 1-22. c) LÍ2CO3, space group C2 / c; J. Alloys Compd. (2011), 509, 7915-7921 d) LÍAIO2, space group R-3m; Marezio etal., J. Chem. Phys. (1966) 44, 3143-3145. e) MnO, space group Fm-3m, Locmelis et al., Z. Anorg. Allg. Chem. 1999, 625, 1573. Rrn Lnn / zznz / E / YiAi Table 1: Characteristic reflections (given position in °2theta and relative intensity in %) of CoxNi1-x, Co, LÍ2CO3, LÍAIO2 and MnO with intensities >10% and 2theta <80° for Cu K radiation alpha 1): Compound hkl 2 theta [%] intensity laughter. [%] COo.áNio.s 111 44.36 100 200 51.68 46 220 76.12 24 Ni 111 44.50 100 200 51.84 46 220 76.38 24 Co 27 101 47.60 100 102 62.74 13 110 76.20 14 LY2CO3 1 1 0 21.24 100 200 23.30 19 2 0-2 30.44 98 002 31.76 96 1 1 -2 34.00 83 3 1 -1 36.72 81 0 2 1 39.44 39 2 2-1 42.48 22 3 1 1 48.58 52 4 2-1 57.34 11 2 2-3 57.90 19 2 0-4 59.58 20 5 1 -3 62.86 12 LIAIO2 003 18.72 100 101 37.60 17 104 45.22 98 107 59.30 17 018 65.02 23 110 66.76 27 MnO 111 34.94 60 200 40.58 100 220 58.72 58 311 70.20 23 222 73.82 17 Rrn Lnn / zznz / E / YiAi In the case of characteristic reflections that overlap with reflections from different crystalline phases (especially graphite, which contributes to the largest fraction of the sample), an additional measurement is carried out using an alternative radiation source (e.g., Mo K alpha instead of Cu K alpha). Abbreviations: In the context of the present invention, normal pressure means 1 atm or 1013 mbar. “Normal conditions” means normal pressure and 20°C. NI means normal liter, liter under normal conditions (1 atm, 20°C). PFA means perfluoroalkoxyalkane polymer. Percentages refer to % by weight unless otherwise specified. The terms % by weight and wt% may be used interchangeably. Where "ambient temperature" is mentioned, it refers to a temperature between 18 and 25°C. XRD means powder X-ray research (radiation as indicated, typically Cu k-alpha1 radiation of 154 pm or Mo k-alpha1 radiation of 71 pm). The invention is also illustrated by the following examples. Example 1: Sample of synthetic product A quantity of 200 g of simulated spent battery slag containing 78.8 g of spent active cathode material containing nickel, cobalt, and manganese in similar molar amounts, approximate formula Li(N0.34Co0.33Mn0.33)02, 62.2 g of organic carbon in the form of graphite and soot 47.0 g of organic electrolyte mixture (containing LIPF6) 7.4 g of polyvinylidene fluoride as a binder, 2.4 g of aluminum powder, 0.2 g of iron powder, 2.0 g of copper metal was placed in a 500 mL quartz round-bottom flask and attached to a rotating evaporator so that the flask was immersed in a furnace. Within 4.5 hours, the rotating flask was heated to 800°C over a period of 2 hours in an argon flow (20 L / h) and held at this temperature for 1 hour in a dry air flow (20 L / h) before being cooled to room temperature. A quantity of 173.3 g of heat-treated material was obtained, comprising a phase composition of Ni / Co alloy, iron manganese oxide, Li₂CO₃, LiF, and graphite. Example 1a: Proportion of a reduced mass from waste lithium-ion batteries A quantity of ~1 t of mechanically treated battery slag containing spent active cathode material containing nickel, cobalt, and manganese, organic carbon in the form of graphite and soot, residual electrolyte, and other impurities comprising, among others, fluorine, phosphorus, and calcium compounds, was treated to obtain a reduced mass according to the process described in Jia Li et al., Journal of Hazardous Materials 302 (2016) 97-104. The atmosphere within the roasting system is air, from which the oxygen reacts with the carbon in the battery slag to form carbon monoxide; the treatment temperature is 800°C. After the reaction and cooling to room temperature, the heat-treated material is recovered from the oven, mechanically treated to obtain a particulate material, and analyzed by powder X-ray diffraction (Figures 1, 2: Mo Ka radiation, Figs. 3, 4: Cu Ka radiation), elemental analysis (Table 2), and particle size distribution (Table 3). The lithium content is 3.6% by weight, which serves as a reference for all other leaching examples (see below). Fluorine is represented primarily as inorganic fluoride (88%). Particle sizes are well below 1 mm; D50 is determined to be 17.36 pm. Comparing the obtained XRD pattern with the calculated reference Ni patterns (which is identical to CoxNi1-x, x = 0-0.6), Co, Li2CO3, and LiAlIO2 (see reference patterns in Table 1), it can be concluded that Ni is present exclusively as a metallic phase, either as pure Ni or as an alloy in combination with Co. For clarity, this result is confirmed by applying two different radiation sources. The presence of metallic nickel is supported by the qualitative observation that the entire sample exhibits typical ferromagnetic behavior when in contact with a permanent magnetic material. Both Li2CO3 and LiAlIO2 are identified as lithium salts. Rrn Lnn / zznz / E / YiAi clearly through its characteristic diffraction pattern. The composition of the black powder (PM) obtained is shown in Table 2. Table 2: Composition of reduced black powder (PM) Rrn Lnn / zznz / E / YiAi F (Ionic F of this) 2.6 g [i.e., 0.14 mol] / 100g (2.3 g [i.e., 0.12 mol] / 100g) C (Inorganic C of this) 31.3 g / 100g (1.2 g / 100g) Ca 0.16 g [i.e., 0.004 mol] / 100g Co 9.5 g / 100g Cu 3.4 g / 100g Li 3.6 g / 100g Mn 5.8 g / 100g Ni 4.8 g / 100g P 0.36 g / 100g Table 3: Results regarding the measurement of the particle size distribution of reduced mass from waste lithium-ion batteries after heat treatment. D10 [gm] D50 [gm[ D80 [gm] D90 [gml 3.46 17.36 33.86 48.92 Example 2: Leaching with Ca(OH)2 A quantity of 5 g of the aforementioned reduced battery slag material (obtained as shown in Example 1a) was loaded into a PFA flask and mixed with 5, 1.5, 1.0, and 0.5 g of solid Ca(OH)2, respectively. 200 g of water were added with stirring, and the entire mixture was refluxed for 4 hours. After 4 hours, the solid contents were filtered out, and the filtered samples were analyzed for Li, F, carbonate, OH, and Ca. The results are compiled in Table 4 below. Table 4: Filtrates analyzed after the leaching of Li with Ca(OH)2 Amount of Ca(OH)2 [gl] Lithium content [mg] Fluoride content [mgl] Li leaching efficiency [%] 0.5 144 46 80 1.0 154 12 84 1.5 156 4 86 5 162 4 90 Example 2a: Leaching with Ca(OH)2, addition of solids to liquids Example 2 is repeated, except that 5 g of the black powder obtained as shown in Example 1 and the designated amount of solid Ca(OH)2 were added simultaneously to 200 g of water with stirring. The results are analogous to those reported in Table 4. Example 3: Higher solids content Amounts of 10, 20, and 30 g, respectively, of the particulate matter (PM) described in Example 1a were loaded into a PFA flask and mixed with solid Ca(OH)₂ in a fixed weight ratio of PM:Ca(OH)₂ = 3.3:1. Further treatment with the addition of 200 g of water followed Example 2, except that each sample was refluxed for 6 hours. The results are shown in the Table 5. Based on the results, it is concluded that the efficiency of the present leaching process is not affected by solid PM content. Table 5: Filtrates analyzed after the leaching of L1 with Ca(OH)2 Rrn Lnn / zznz / E / YiAi Quantity of material from Example 1 Lithium content [mg] Fluoride content [mg] Li leaching efficiency 10g 322 10 89% 20g 624 20 86% 30g 987 30 91% Example 4: Parameter variation Following the procedure in Example 2a, solid Ca(OH)₂ and the particulate matter (PM) described in Example 1a were added with stirring (3-stage crossbeam stirrer, 60 mm diameter) to 836.8 g of preheated water in a baffled glass reactor. Stirring was continued at a constant temperature for the period (t) indicated in Table 6, after which the solid was filtered out and the filtered samples were analyzed. The amounts of Ca(OH)₂ and PM, temperatures, stirring parameters, and analysis results (% = g found in 100 g of filtrate) are also compiled in Table 6. Table 6: Sample t [h] L¡ [%] F- [%] Li recovered (%) 125.5 g PM, 37.7g Ca(OH)2 T = 70°C, shake with 525 rpm (0.85 W / kg) 0 2 0.28 0.024 55% 3 0.28 0.022 55% 4 0.30 0.021 59% 6 0.33 0.014 65% 24 0.41 0.007 80% 125.5 g PM, 37.7g Ca(OH)2 T = 95°C, stir with 525 rpm (0.85 W / kg) 0 2 0.41 0.016 80% 3 0.43 0.015 84% 4 0.44 0.015 86% 6 0.47 0.014 92% 24 0.48 0.014 94% 125.5 g PM, 37.7g Ca(OH)2 T = 98°C, stir at 950 rpm (5 W / kg) 0 2 0.42 0.014 82% 3 0.43 0.013 84% 4 0.45 0.013 88% 6 0.45 0.013 88% 24 0.48 0.016 94% 167.4 g PM, 50.2g Ca(OH)2 T = 98°C, stir at 600 rpm (1.3 W / kg) 0 2 0.49 0.019 72% 3 0.53 0.018 78% 4 0.54 0.018 79% 6 0.55 0.018 81% 24 0.64 0.029 94% Example 5: Solid LiOH from leached lithium filtrate A filtrate obtained from a process according to Example 2 was further treated according to step (e1) described above to obtain solid LiOH as monohydrate: 1 L of a filtrate containing 0.21 wt% lithium was concentrated by evaporation (40°C, 42 mbar) and then dried at 40°C under a constant flow of nitrogen for 24 h. Figure 5 shows the LiOH monohydrate obtained with minor impurities of U₂CO₃. The latter occurs due to contact with air during almost all stages of the process. Along with carbon-based impurities, elemental analysis reveals major impurities (>200 ppm) of F, Na, Ca, K, and Cl, and minor impurities (<200 ppm) of Al and Zn. BRIEF DESCRIPTION OF THE FIGURES Figure 1: Reduced mass powder (Mo Ka) X-ray diffractogram from waste lithium-ion batteries after the heating / reduction treatment obtained in Example 1a and used in Example 2a, including reference diffractograms of graphite, cobalt, manganese(II) oxide, cobalt oxide, and nickel. Figure 2: Reduced mass powder (Mo Ka) X-ray diffractogram from waste lithium-ion batteries after the heating / reduction treatment obtained in Example 1a and used in Example 2a, including reference diffractograms of graphite, lithium alumina, and lithium carbonate. Figure 3: X-ray diffractogram of mass reduced (Cu Ka) powder from waste lithium-ion batteries after the heating / reduction treatment obtained in Example 1a and used in Example 2a, including reference diffractograms of graphite, cobalt, manganese(II) oxide, cobalt oxide, and nickel. Figure 4: X-ray diffractogram of mass-reduced (Cu Ka) powder from waste lithium-ion batteries after the heating / reduction treatment obtained in Example 1a and used in Example 2a, including reference diffractograms of graphite, lithium alumina, and lithium carbonate. Figure 5: Powder X-ray diffractogram (Cu Ka) of LiOH monohydrate obtained in Example 5.

Claims

1. A process for recovering lithium from a material comprising waste lithium-ion batteries, or parts thereof, wherein said process comprises the steps of (a) providing a particulate material containing a transition metal compound and / or a transition metal, wherein the transition metal is selected from the group consisting of Mn, Ni and Co, and wherein, furthermore, at least a fraction of said Ni and / or Co, if present, is in an oxidation state less than +2 and at least a fraction of said Mn, if present, is manganese(II) oxide; wherein the particulate material further contains a lithium salt and a fluoride salt, and wherein the particulate material optionally contains calcium provided that the element ratio between calcium and fluorine is 1.7 or less, i.e., zero; (b) treat the material provided in step (a) with a polar solvent and an alkaline earth hydroxide; and (c) separate the solids from the liquid, optionally followed by washing the solid residue with a polar solvent, such as water.

2. The process according to claim 1, wherein the particulate material provided in step (a) is obtained from waste lithium-ion batteries, in particular the cell materials thereof, and is provided in the form of a dry powder, a wet powder or a suspension of particles in a liquid.

3. The process according to claim 1 or 2, wherein the particulate material provided in step (a) comprises particles having an average particle diameter D50 in the range of 1 qm to 2 mm when detected according to ISO 13320 EN:2009-10.

4. The process according to any of the preceding claims, wherein the transition metal compound and / or the transition metal Ni and / or Co in an oxidation state less than +2, contained in the particulate material provided in step (a), comprises Ni and / or Co in the metallic state and wherein the transition metal compound and / or the transition metal contained in the particulate material provided in step (a) is preferably present in an amount detectable by powder X-ray diffractometry (Cu-k-alpha-1 radiation).

5. The process according to any of the preceding claims, wherein the lithium salt and fluoride salt contained in the particulate material provided in step (a) comprise one or more salts of UOH, LiF, Li2O, Li2CO3, LiHCO3, lithium aluminate, lithium phosphate salts; mixed oxides of Li and one or more of Ni, Co, Mn, Fe, Al, Cu and / or fluorides of Ni, Co, Mn, Fe, Al, Cu.

6. The process according to any of the preceding claims, wherein step (b) is carried out by i) the addition of the alkaline earth hydroxide and / or an alkali oxide, as a solid, or a mixture comprising the alkaline earth hydroxide as a suspension or solution in a protic solvent, such as an aqueous liquid, and the particulate material provided in step (a) simultaneously to the polar solvent, which is a protic solvent and preferably an aqueous liquid, such as water; or by i) the addition of the particulate material provided in step (a) to the polar solvent, which is a protic solvent and preferably an aqueous liquid, such as water; to obtain a suspension, followed by the addition of the alkaline earth hydroxide and / or an alkali oxide, as a solid, or a mixture comprising the alkaline earth hydroxide as a suspension or solution in a protic solvent, generally in an aqueous liquid;or by (ii) adding the alkaline earth hydroxide and / or an alkali oxide, as a solid or suspension of solids in a polar solvent, to an aqueous liquid, such as water, to obtain a mixture comprising alkaline earth hydroxide, in general, as a suspension or solution in the aqueous liquid, and subsequently combining said mixture with the particulate material provided in step (a); or by (iv) adding the alkaline earth hydroxide and / or an alkali oxide, as a solid, to the particulate material provided in step (a) to obtain a mixture of solids, followed by adding the polar solvent, which is a protic solvent and preferably an aqueous liquid, such as water; or by (v) adding the particulate material provided in step (a) to the polar solvent, which is a protic solvent and preferably an aqueous liquid, such as water;to obtain a suspension, followed by filtration to obtain a filtrate and subsequently adding the alkaline earth hydroxide and / or an alkali oxide, as a solid, or a mixture comprising the alkaline earth hydroxide, in general as a suspension or solution in the polar solvent, preferably an aqueous liquid, to the filtrate.; 7. The process according to any of the preceding claims, wherein the alkaline earth hydroxide added in step (b) is calcium hydroxide added as such or the calcium hydroxide is formed in situ by contacting the calcium oxide with the polar solvent, which is a protic solvent, such as an aqueous liquid or water.

8. The process according to any of the preceding claims, wherein the particulate material provided in step (a) comprises material obtained from waste lithium-ion batteries after carrying out the preliminary step (i) of heating under inert or reducing conditions to a temperature in the range of 80 to 900°C, especially 200 to 800°C, said preliminary step (i) generally being carried out after the discharge of the lithium-ion batteries, dismantling and / or crushing.

9. The process according to claim 8, wherein the heating step (i) is carried out under reducing conditions comprising the presence of carbon and / or a reducing gas selected from hydrogen and carbon monoxide.

10. The process according to claim 8 or 9, wherein in the preliminary step (i) the heating temperature is in the range of 350 to 500°C, especially 350 to 450°C, and preferably step (i) is carried out in the presence of 35% or more by volume of hydrogen.

11. The process according to any of the preceding claims, wherein the particulate material provided in step (a) is obtained from lithium-ion batteries after mechanical removal of the casing, wiring or circuitry and discharge, and wherein said material is not exposed to temperatures of 400°C or more under oxidizing conditions prior to being subjected to the present step (a).

12. The process according to any of the preceding claims, comprising the additional step (d) of subjecting the solids obtained in step (c) to a solid-solid separation.

13. The process according to any of the preceding claims, comprising the additional step (f) of recovering the transition metals nickel and / or cobalt by pyrometallurgical or hydrometallurgical treatment of the solid residue obtained after carrying out step (c) or (d).

14. The process according to any of claims 1 to 11, comprising the additional step of recovering lithium as lithium hydroxide by crystallization from the liquid obtained in step (c) or recovering lithium as lithium carbonate after adding carbon dioxide to the liquid obtained in step (c) and isolating from the lithium carbonate formed.

15. The solid obtainable in step (c) of the process according to any one of claims 1 to 11, in particular in the form of a particulate material, wherein the solid contains calcium, lithium and at least one of Ni, Co and Mn, wherein at least a fraction of said Ni and / or Co, if present, is present in the metallic state and at least a fraction of said Mn, if present, is manganese(II) oxide; characterized in that the weight ratio of (Ni + Co + Mn) : L in said solid is in the range of 30 :100000, and said solid contains, by weight of the dry solid, 2 to 35% calcium.

16. A lithium hydroxide product, as obtainable by crystallization from the liquid separated in step (c) according to the process of any one of claims 1-11 or 14, comprising lithium hydroxide monohydrate containing 100 ppm to 1.29% calcium, 0.1 to 1.29% fluorine, 0.1 to 1.29% sodium; or anhydrous lithium hydroxide containing 175 ppm to 2.26% calcium, 0.175 to 2.26% fluorine, 0.175 to 2.26% sodium; or wherein all amounts are by weight of the dry solid.

17. A lithium hydroxide product according to claim 16, as obtainable by crystallization from the liquid separated in step (c) according to the process according to any of claims 1-11 or 14, comprising lithium hydroxide monohydrate containing 100 ppm to 1.29% calcium, 0.1 to 1.29% fluorine, 0.1 to 1.29% sodium, 20 ppm to 1.29% zinc, 50 ppm to 1.29% aluminum, 0.1 to 1.29% potassium, 0.1 to 1.29% chlorine; or anhydrous lithium hydroxide containing 175 ppm to 2.26% calcium, 0.175 to 2.26% fluorine, 0.175 to 2.26% sodium, 35 ppm to 2.26% zinc, 87 ppm to 2.26% aluminum, 0.175 to 2.26% potassium, 0.175 to 2.26% chlorine; wherein all amounts are by weight of the dry solid.