EP4359576A1

EP4359576A1 - Process for recycling battery materials by way of reductive, pyrometallurgical treatment

Info

Publication number: EP4359576A1
Application number: EP22735396.8A
Authority: EP
Inventors: Juliane Meese-Marktscheffel; Armin Olbrich; Alexander Wolff; Alexander EGEBERG; Tino Saeuberlich; Alexander ZEUGNER
Original assignee: HC Starck Tungsten GmbH
Current assignee: HC Starck Tungsten GmbH
Priority date: 2021-06-23
Filing date: 2022-06-21
Publication date: 2024-05-01
Also published as: US20240283045A1; WO2022268792A4; WO2022268792A1; KR20240026492A; CN117500948A; MX2023015163A; AU2022299266A1; BR112023026135A2; CL2023003852A1; JP2024524935A; CA3220638A1

Abstract

The present invention relates to a process for recycling battery materials, in particular lithium ion/polymer batteries, and to the subsequent use of the useful materials recovered by way of the process according to the invention.

Description

Process for recycling battery materials using reductive pyrometallurgical treatment

The present invention relates to a recycling process for battery materials, in particular lithium-ion/polymer batteries, and the further use of the valuable materials recovered by means of the process according to the invention.

Electromobility is considered a central component of a sustainable and climate-friendly transport system based on renewable energies and is part of the global megatrend "Advanced Mobility", which is not only being intensively discussed in society and politics, but has also now arrived in industry all types of electric vehicles: electric bicycles, motorcycles, forklifts, ferries and sports boats, hybrid cars, plug-in cars and all-electric cars through to electric buses and hybrid or all-electric trucks. In this context, batteries, in particular the so-called lithium-ion/polymer accumulators (hereinafter abbreviated to LIB) have been established.

With the increasing demand for electric vehicles, not only the need for corresponding drive and energy storage systems is increasing. There is also the question of how these systems can be integrated into a clean and circular economy, which will certainly become more important in the future from the point of view of sustainability. The strategic relevance of recycling these systems is therefore an essential building block in the entire value chain of the global megatrend of mobility and thus an indispensable part of international efforts to achieve climate goals. It is therefore absolutely necessary to be able to make key materials for electromobility available as quickly as possible through environmentally friendly, energy- and cost-efficient and socially responsible recycling processes. The emancipation from the classic primary raw material extraction of battery-relevant materials to the sustainable and nevertheless economical handling of the same through the development and large-scale implementation of innovative recycling processes will increasingly come to the fore globally.

Typical elements that are used in LIB in metallic form or in the form of their compounds are iron (Fe), aluminum (Al), and copper (Cu), manganese (Mn), nickel (Ni) and cobalt (Co) as well as lithium (Li) and graphite in various modifications, which mainly make up parts of the housing, the electrical supply lines but also in particular the electrode materials and, depending on the battery type, Batte riebauart and battery embodiment can occur in a wide variety of ratios in addition to the quantitatively subordinate electrolyte and separator materials. The extraction of some of these raw materials often takes place under precarious conditions that have far-reaching social and environmental impacts. Mention should be made in this context, for example, of the existence of child labor, e.g. B. in the manual mining of cobalt or from an environmental point of view extremely questionable influence of lithium extraction on the water balance in desert areas and plateaus. Considering the massive social and environmental impacts associated with the ever-increasing demand for these strategic raw materials, the recycling of LIBs and related systems, as outlined above, plays a key role in the sustainable transition to alternative energy storage systems. Due to the complexity of the material compositions and the use of substances and mixtures classified as carcinogenic and their electrical and chemical energy content, the recycling of LIBs is not only a purely technological challenge, but also involves a number of health, safety and environmental risks that are involved has to be mastered.

Initial attempts to establish a closed cycle for LIBs resulted in various recycling processes that have so far only been implemented in a few industrial plants worldwide. All of these methods are characterized by long and complex process chains and are based on a combination of mechanical and/or thermal and/or pyrometallurgical and hydrometallurgical process steps. L. Brückner et al provide an overview of the common processes in their review article: "Industrial Recycling of Lithuim-Ion Batteries - A Critical Review of Metallurgical Process Routes", published in Metals 2020, 10, 1107.

In the context of the following explanations and the present invention, a distinction is made between the systems lithium batteries, rechargeable lithium batteries and lithium accumulators, rechargeable lithium-ion batteries and lithium-ion accumulators and rechargeable lithium-polymer batteries and lithium-polymer -accumulators waived. All systems are considered synonymous to each other here and are summarized under the term "LIB", unless expressly stated otherwise.

Currently, two variants for recycling LIBs have been established, the first based on a combination of pyrometallurgical and hydrometallurgical treatments, while the second relies on a mechanical treatment, possibly with an upstream or downstream thermal stage, before the actual hydrometallurgical processing.

A pyrometallic treatment of used LIBs or residues from battery production, as is carried out, for example, in the first variant described, usually produces Co, Cu and Ni-containing molten alloys (metallic phase), an Al, Mn and Li-containing liquid slag and fly ash. The metallic phases and the slag can then be further treated hydrometallurgically in order to obtain the individual metals using known methods in multi-stage processes.

In the second variant described, the LIBs are first treated mechanically, typically resulting in magnetic and non-magnetic metal concentrates such as Al and Cu concentrates and a fraction containing the active electrode materials, the so-called black mass. The mechanical treatment can optionally be preceded by a thermal treatment in order to reduce the energy content in a controlled manner and to specifically remove organic components and halides. In the case of larger traction batteries in particular, it can also be advantageous for safety reasons to have an upstream electrical residual discharge of the LIBs. The black mass resulting from these processes can then either be subjected to a pyrometallurgical treatment, corresponding to the first variant described, or, which is preferred, subjected directly to a hydrometallurgical treatment. Depending on the composition of the black mass and the respective prior treatment procedure, thermal treatment can also be advantageous in order to remove organic components and halides present at this point and to increase the metal content. During the hydrometallurgical treatment, Co, Li, Mn, Ni and, if present, graphite can be recovered. In the following, the processing of used LIBs is presented as an example using the second variant, as is known in the prior art:

The mechanical treatment of the disused LIBs usually begins with crushing to release the components of the LIBs. In the case of large batteries from electric drives, an electrical deep discharge is also advantageous. Thereafter, the components can be sorted according to their physical properties, such as particle size, shape, density, and electrical and magnetic properties. Crushing usually produces concentrates for further metallurgical processes.

Pyrometallurgy includes high-temperature processes such as roasting or smelting to separate, extract and refine metals. The term roasting is commonly understood to mean processes such as gas-solid reactions that allow ores or secondary raw materials to be converted into other, more processable chemical substances or mixtures, with some of the undesirable components often being removed in gaseous form. In smelting, the metal is extracted from the ore or secondary raw material with the help of heat and chemical reducing agents, decomposing the ore or secondary raw material and expelling other elements in the form of gas or being trapped in slags or enriched to form alloys or at best the to obtain pure metal.

Hydrometallurgy refers to the entirety of processes in metal extraction and refining, which, in contrast to pyrometallurgy, take place in solution at comparatively low temperatures. Hydrometallurgical processes usually involve various steps. In a first step, the metal is dissolved by leaching, usually with the help of acids, bases or salts. In a subsequent step, purification takes place, for example by liquid/solid reactions such as ion exchange reactions and precipitation or liquid/liquid reactions such as solvent extraction. In a final step, the element of value that is initially in solution is precipitated, either directly as a metal or as a chemical compound, often in salt form, for example by crystallization, ionic precipitation, reduction with gases, electrochemical reduction or electrolytic reduction. Like other battery types, LIBs are usually made up of a cathode, an anode, an electrolyte and a separator. The components can vary depending on the battery type and manufacturer and therefore have a major impact on possible recycling processes.

Commercial high-performance cathode materials in LIBs are typically LiCo oxides (LCO), Li(Co/Ni) oxides (LCNO), Li(Ni/Co/Mn) oxides (LNCMO), Li(Ni/Co/Al) oxides (LNCAO) or Li(Ni/Al) oxides (LNAO) in the form of UMO2 layer structures (with M = Ni, Co and/or Mn), which can optionally be doped with Al for stabilization, or also Li(Ni/ Mn) oxides in the form of LiM2O4 spinel structures, whereby only the main components that are essential for recovery from the point of view of supply technology and economics are mentioned. There is also a variety of other doping elements, which, depending on battery or cathode material manufacturers and the respective intended use of the rechargeable batteries, extends to various other subgroup metals, including the rare earth elements, but also main group elements of the periodic table.

Furthermore, Li metal phosphates of the structure UMPO4 (M=Fe, Mn, Co, Ni), also in variously doped form, can be used, but due to their usually high content of less valuable iron and phosphorus in the main component LiFePÜ4 in the desired recycling processes play a subordinate role.

The most common cathode materials known from literature are as layer structures LCO (UC0O2), NMC (LiNixMn _y COz0 ₂ with x+y+z=l), NCA (UNixCo _y Al _z 02 with x+y+z=l, especially LiNi0.8Co0. 15AI0.05O2) and as spinel LiMn2Ü4 and LFP (LiFeP04), which is present in olivine structure, with the positions of the SiÜ4 tetrahedra in olivine ((Mg,Fe)2Si04) being occupied by P04 tetrahedra.

So-called end-of-life LIBs to be recycled or waste from LIB production (off-spec) can only be used to a limited extent as starting material due to their high aluminum content, which mainly comes from the housing, and significant amounts of lithium and organic compounds suitable for classic smelting processes, such as those used for the production of Co, Ni or Cu, since lithium in particular is known to attack the furnaces. Another problem is that the established processes are based on recovery of Co, Cu and Ni and that lithium, together with aluminum and manganese, occurs only in low concentrations in the form of slags from which it is difficult to extract again.

To address these issues, a number of processes have been developed that specifically focus on the preparation of LIBs. These processes allow lithium to be enriched in the slag and use special furnaces designed for highly corrosive materials.

In this regard, US 7,169,206 describes a process for the recovery of Co or Ni in which a metallurgical charge of iron, slag formers and a payload containing either nickel or cobalt or both is placed in a shaft furnace and smelted to produce a Co/Ni - Alloy, a ferrous slag and a gas phase are formed. The payload comprises at least 30% by weight of batteries or their scrap, and the redox potential of the shaft furnace is chosen such that the slag contains at least 20% by weight of iron and a maximum of 20% by weight of the nickel and/or cobalt of the payload . Although LIBs are mentioned as suitable starting materials, no further details are given as to whether and in what quantities lithium could be recovered.

EP 2 480 697 also describes a method for recovering Co from Li-ion batteries also containing Al and C, comprising the steps of: providing a bath furnace equipped with O2 injection means; providing a metallurgical charge comprising Li-ion batteries and at least 15% by weight of a slag former; feeding the metallurgical charge to the furnace with injection of O2, reducing and collecting at least part of the Co in a metallic phase; Separation of the slag from the metallic phase, the process being carried out under autogenous conditions in which the proportion of Li-ion batteries, expressed in % by weight of the metallurgical load, is equal to or greater than 153%-3.5 (Al% + 0.6 C%) where Al% and C% are the wt% of Al and C in the batteries. Although it can be seen from the examples that the slag obtained also contained Li, a further treatment of the slag to isolate the lithium is not described.

WO 2011/141297 describes a method for the production of lithium-containing concrete, in which lithium-containing scrap metal to obtain a metallic phase and a lithium-containing slag is melted, the slag is separated from the metallic phase, the slag is solidified by cooling, and then the slag is processed into a powder having a particle size D90 of less than 1 mm. The pulverized slag is then added to concrete or mortar to prevent unwanted ASR (Alkali Silica Reactions), but this removes the lithium from the material cycle forever.

Further investigations have shown that the lithium content of the slags obtained is comparable to that of spodumene concentrates, which, along with lithium-containing brine, form the largest commercial source of lithium in the area of lithium-containing primary raw materials. As part of various research projects, methods for extracting lithium from slags of different compositions have been developed. In a first step, the slag was ground to a powder on a micrometer scale and then leached with H2SO4 or HCl at 80 °C, with an acid concentration of around 10 g/L having been found to be advantageous. To remove aluminum, the pH of the leachate was then adjusted to pH 5 and aluminum hydroxide precipitated. After filtration and concentration of the lithium content in the leach solution, the lithium was then precipitated as lithium carbonate at pH 9 to 10 using Na2CÜ3. Under optimized conditions, a lithium yield of 60 to 70% could be achieved. However, the process has the disadvantage that the low lithium content in the slag results in a high proportion of waste and the U2CO3 obtained has a high level of impurities.

An alternative recycling process of LIBs is based on a combination of mechanical treatment and pyrometallurgical and/or hydrometallurgical treatment, in which a certain fraction, the so-called black matter, is in the foreground. In an optional pre-treatment, the LIBs are subjected to a thermal treatment, e.g. pyrolysis, to reduce the energy content in a controlled manner and to remove organic components. After the material obtained has been crushed, it can be separated by sieving, sorting or magnetically, with typical fractions being Al/Cu foils, non-magnetic metals such as aluminum or copper in lump or powder form, magnetic metals and a fraction known as black matter, which essentially consists of the active materials of the batteries, i.e. the cathode material with the Main components Ni, Co, Mn, Al and Li and optionally graphite from the anode material can be isolated. With the exception of the black matter, all the fractions obtained can be fed into conventional treatment processes.

Due to its already reduced aluminum content, the black mass is more suitable for conventional pyrometallurgical processes than LIBs. However, due to the corrosive properties of lithium and the complex processing of the lithium-containing slag and the high losses of lithium during processing, the problem of efficient recovery of lithium in this way remains unsolved.

WO 2017/121663 relates to a lithium-containing slag containing 3 to 20% by weight U2O, 1 to 7% by weight MnO, 38 to 65% by weight Al2O3, less than 55% by weight CaO and less than 45% by weight % S1O2. The lithium-containing slag can be obtained by melting battery materials, where it occurs together with a metallic phase. For this purpose, spent lithium-ion batteries are introduced into a furnace together with limestone (CaCÜ3) and sand (S1O2) in the presence of oxygen. Due to the high content of metallic aluminum and carbon in the batteries, a temperature of 1400 to 1700 °C is reached. The resulting alloy melt and slag are separated and the lithium is isolated from the slag. Although more than 50% of the lithium is said to accumulate in the slag, part of the lithium could not be prevented from being discharged together with the exhaust gases. According to the amounts of battery material used according to the examples, the person skilled in the art would expect a content of 12.42% U2O in the slag, but in fact Table 1 only gives a content of recovered lithium of 8.4%, so that a loss of 32. 4% of the lithium used can be booked.

On the hydrometallurgical side, the focus is currently on two alternatives. In the first alternative, attempts are made to obtain intermediate products by means of leaching and precipitation, in which Ni/Co and manganese and lithium can then be purified separately in existing refineries. The second alternative envisages the direct manufacture of more complex products. Both processes provide for a gradual separation of the elements, in which first manganese, cobalt and nickel are each separated off one after the other and in one last step lithium is isolated in the form of U2CO3. Figures 1 and 2 show an overview of the two methods.

WO 2018/184876 describes a method for recovering lithium from a lithium and aluminum-containing metallurgical composition, comprising the steps of: leaching the metallurgical composition by contacting it with an aqueous sulfuric acid solution at a pH of 3 or less, resulting in a residue containing insoluble compounds and a first leachate comprising lithium and aluminum is obtained; optionally neutralizing the first leachate comprising lithium and aluminum to a pH of 2 to 4, thereby precipitating a residue comprising a first portion of the aluminum and obtaining a second leachate comprising lithium; adding a phosphate ion source to the first leachate comprising lithium and aluminum or, provided that the optional neutralization of the first leachate is performed, to the second leachate comprising lithium and aluminum, thereby precipitating a residue comprising a second comprising part of the aluminum and obtaining a third leachate comprising lithium; optionally neutralizing the third leachate comprising lithium and aluminum to a pH of 3 to 4, thereby precipitating a residue comprising a third portion of the aluminum and obtaining a fourth leachate comprising lithium; and separating the residue comprising the second portion of the aluminum from the third leachate by filtration, or, provided that the optional neutralization of the third leachate is performed, separating the residue comprising the third portion of the aluminum from the fourth leachate by filtration. The lithium can then be obtained in the form of U2CO3 using known processes such as classic carbonate precipitation. In this way, a better separation of aluminum and lithium is to be achieved and the content of recovered lithium is to be increased.

WO 2019/149698 relates to a method for recycling lithium batteries, with the steps (a) digestion of material to be comminuted, which contains comminuted components of electrodes from lithium batteries, with concentrated sulfuric acid at a digestion temperature (AT) of at least 100 ° C, so that an off-gas and a digestion material are produced, (b) discharging the off-gas and (c) at least one wet-chemical extraction of at least one metallic component of the digestion material.

WO 2020/011765 discloses a process for the recovery of transition metal from spent nickel-containing lithium-ion batteries, the process comprising the following steps: (a) heating a lithium-containing transition metal oxide material derived from lithium-ion batteries and fluorine compounds and/or compounds of phosphorus as impurities to a temperature ranging from 200 to 900 °C in the presence of H2, (b) treating the product obtained in step (a) with an aqueous medium, (c) solid-solid separation to remove Ni from the solid residue of step (b), (d) recovering Li as hydroxide or salt from the solution obtained in step (b) and (e) extracting Ni and optionally Co from the solid obtained in step (c). Ni concentrate.

J. Hu et al describe an approach for this in their article "A promising approach for the recovery of high value-added metals from spent lithium-ion batteries", published in Journal of Power Sources, 351 (2017), 192-199 Recycling high value-added metals from the cathode materials of used LIBs using reduction roasting to break down LiNixCo _y Mn _z 02 into simple compounds or metals.

CN 108539309 relates to a method for recovering waste lithium nickel cobalt manganese oxide cathode material, in which the material is first freeze-dried and screened, the screened material obtained is placed in a reduction furnace and hydrogen is fed under specific conditions for reduction. The raw material thus obtained is stored in a storage box filled with nitrogen, and then washed by adding hot pure water and adding carbon dioxide to obtain a lithium hydrogen carbonate solution and aluminum hydroxide precipitate. Hydrazine is added to the cobalt, nickel and manganese residues, their metallic form is converted and then magnetically separated.

WO 2020/212587 discloses a method for producing battery precursors with the recovery of metals M from a starting material containing Li, M comprising Ni and Co, comprising the following steps: Step 1: providing the starting material, the Li-ion batteries or its derivative products includes; Step 2: Remove Li in an amount of more determined as the maximum of (1) 30% of the Li present in the feedstock and (2) a percentage of the Li present in the feedstock to obtain a Li:M ratio of 0.70 or less in a subsequent acidic leach step, using either one or more of the following processes: (a) a pyrometallurgical smelting process using slag formers, whereby one or more Li-containing slag phase and Li-containing flue gases and a Li-depleted Ni-Co-containing phase are acid leached can, be generated; (b) a thermal treatment process using a reducing agent, thereby producing a Ni-Co-containing residue containing at least one water-soluble Li compound, and removing the at least one Li compound by washing with an aqueous solution, thereby producing a Li depleted Ni-Co containing residue which can be acid leached; (c) a hydrometallurgical leaching process using an aqueous or acidic solution, whereby Li is leached from the feedstock, with Ni and Co being at least partially insoluble, and solid-liquid separation, whereby a Li-depleted Ni-Co-containing residue is obtained suitable for acid leaching; Step 3: subsequent leaching using relative amounts of Li-depleted Ni-Co-bearing material obtained in Step 2 and a mineral acid, whereby a Ni- and Co-bearing solution is obtained; and step 4: crystallization of Ni, Co and optionally Mn.

CN 109652655 describes a method for recovering lithium during the processing of a lithium battery, in which a lithium-rich solution is obtained from the lithium batteries by treatment with CO2 and subsequent pyrolysis.

CN 107324392 proposes a process for the recovery of lithium manganese oxide materials under reductive conditions, in which the material is heated in the presence of hydrogen, followed by an aqueous work-up to obtain a lithium hydroxide solution.

In "Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation: A comprehensive review", P. Meshram, Hydrometallurgy 150 (2014), 192-208, present various methods and processes for the extraction of lithium from primary and secondary sources sources before. The methods described in the prior art have the disadvantage that the proportion of lithium recovered has been relatively low and the lithium is usually separated only as the last element, which results in high losses and disruptions caused by the lithium in the preceding process steps cannot be ruled out. An earlier extraction of lithium from the black mass is therefore of great interest.

In addition, no large-scale processes are currently available that allow efficient recovery of lithium from LIBs.

Conventional pyrometallurgical processes achieve high yields of Co, Cu and Ni in the alloy melts. However, lithium can only be recovered in special processes that require a concentration of lithium in the slag. Consequently, plants for the recovery of the valuable metals nickel, copper and especially cobalt, as they are currently used, have major disadvantages when a certain recovery rate for lithium is legislated, as expected after the reform of Directive 2006/66/EC, which sets the legal bases for recycling LIBs.

In hydrometallurgical processes, only small losses are observed for Co, Cu and Ni, but corresponding processes are not available for lithium. In the literature, possible recovery rates for Li from the slag are given as approx. 90%, but the total Li recovery is likely to be lower, since it is assumed that lithium is partially fumed up in pyrometallurgy, as also described in WO 2017/121663 .

Against this background, the object of the present invention is to provide a method for recycling LIBs which allows improved recovery of the elements, in particular the active cathode material and in particular the lithium used. In particular, the method according to the invention should enable the separation of lithium right at the beginning of the work-up process, so that it does not have to be carried along through the entire process chain.

Surprisingly, it has been shown within the scope of the present invention that the previous problems in the recovery of lithium from LIBs can be largely overcome by using the lithium, in contrast to the conventional methods, by means of a reductive treatment of a Li(I)-containing composition, without the formation of the usual molten phases, is already separated as one of the first elements.

Instead of dragging the lithium through the entire processing and separation process, the method according to the invention provides for the separation of the lithium from the other metals nickel, cobalt and manganese right at the beginning of the process chain. This could be achieved in that a Li(I)-containing composition, unlike usual, does not undergo a conventional pyrometallurgical treatment, which usually requires temperatures well above 1000 °C and provides liquid metal phases and liquid slag, but a reductive treatment in the solid state without the addition of slag-forming agents. In this respect, the method according to the invention is characterized in that a solid Li(I)-containing composition, for example in powder form, is subjected to a reductive treatment, a lithium(I)-containing solution and again a solid, the reduction product, being obtained. In this way, the amount of lithium recovered could be significantly increased.

Therefore, a first object of the present invention is a method for recycling LIB materials, comprising the following steps: a) Washing a lithium(I)-containing composition, the lithium(I)-containing composition being from used lithium-ion batteries is won; b) heating the washed composition containing lithium(I) in the presence of a reducing agent, c) suspending the product obtained in step b) in an aqueous or organic suspension medium to obtain a solid reduction product and a solution containing lithium(I) and d) Separating the solid material to be reduced from the lithium(I)-containing solution.

In the context of the present invention, it has surprisingly been found that the combination of washing and reducing treatment can effectively convert the lithium from the lithium compounds contained in the composition into compounds soluble in the suspension medium, while other components of the LIBs such as nickel, manganese and cobalt as insolubles Components remain in the solid material to be reduced. The lithium(I)-containing solution and the material to be reduced can then be separated and worked up separately from one another. Surprisingly, it has been shown that the proportion of recovered lithium could be significantly increased by washing the lithium(I)-containing composition. The method according to the invention thus offers the possibility of separating lithium from the other components right at the start of the recycling process, instead of carrying it along through the entire process of separating nickel, cobalt and manganese, as described in the prior art.

In the context of the present invention, composition is understood to mean a lithium(I)-containing composition, unless stated otherwise.

A reducing agent in the context of the present invention is understood as meaning a substance or a compound which can reduce other substances by donating electrons and is itself oxidized in the process, ie its oxidation number increases.

In the context of the present invention, element and the general designation lithium, nickel, cobalt, manganese, etc. are to be understood as meaning the general generic designation which includes the elements in all their oxidation numbers occurring in the context of the process according to the invention, unless stated otherwise. For example, the term "nickel" includes nickel in the +III oxidation state, such as found in Li(Ni,Co,Mn)O 2 , nickel in the +11 oxidation state, such as found in NiO or Ni(OH) 2 , and Nickel in the 0 oxidation state as it exists in the form of nickel metal.

In contrast to conventional methods, no slag and alloy melts are produced in the method according to the invention. Rather, the method according to the invention is characterized in that both the composition used as the starting material and the product to be reduced are in the form of powder, which significantly simplifies their handling. Therefore, in a preferred embodiment, the composition and/or the material to be reduced, in particular the material to be reduced, is in the form of a powder, preferably with a particle size of less than 500 μm, preferably less than 250 μm, particularly preferably less than 200 μm, in particular less than 100 μm according to ASTM B822. Furthermore, within the scope of the method according to the invention, the use of slag-forming agents or fluxes, such as those used in conventional methods, can advantageously be dispensed with. A preferred embodiment is therefore characterized in that the method is carried out without the addition of slag-forming agents and/or flux.

The method according to the invention is distinguished in particular by the fact that the lithium is separated off first. The elements nickel, cobalt, manganese and, if appropriate, aluminum are only subjected to a further separation into, if appropriate, first groups and finally to pure compounds of the individual elements only after they have been separated from the lithium. Therefore, an embodiment is preferred in which the main amount of lithium is separated before the separation of nickel, cobalt, manganese and optionally aluminum from the composition, the separated amount of lithium preferably being greater than 80%, particularly preferably greater than 90%, based on the original Lithium content is. The lithium is preferably separated from a suspension which contains at least one of the elements nickel, manganese and cobalt as solid components.

The method according to the invention was developed primarily for the recycling of LIBs, both from corresponding end-of-life batteries and from off-spec materials, by-products and waste from the actual battery production. Therefore, an embodiment is preferred in which the composition is obtained from or consists of used LIBs, production waste and by-products that arise in the production of LIBs, in particular in the production of the electrode materials.

In a further preferred embodiment, the composition is obtained from used LIBs. In a particularly preferred embodiment, the composition is lithium cathode materials, production waste from the production of lithium cathode materials and production waste from the production of lithium batteries/accumulators, in particular lithium ion/polymer batteries.

In a further preferred embodiment, the composition is black mass. Black matter in the context of the present invention is understood to mean the fraction that occurs during the mechanical and, if necessary, pyrolytic processing of used LIBs, especially lithium batteries/accumulators, in particular lithium-ion/polymer batteries, waste from LI B production or precursor components of the same is obtained and essentially contains the cathode materials, ie generally compounds of lithium with Co, Ni and/or manganese and their pyrolysis products, and graphite as the basic anode material. Typical compositions of the cathode materials are LiCo oxides (LCO), Li(Co/Ni) oxides (LCNO), Li(Ni/Co/Mn) oxides (LNCMO), Li(Ni/Co/Al) oxides (LN CAO), or Li(Ni/Al) oxides (LNAO) in the form of LiMO2 layer structures with M = z. B. Ni, Co and/or Mn, optionally doped with Al, or Li(Ni/Mn) oxides in the form of UM2O4 spinel structures or Li metal phosphates L1MPO4 (M=Fe, Mn, Co, Ni). Particularly common cathode materials are LCO (UC0O2), NMC (LiNi _x Mn _y Coz02 with x+y+z=l), NCA (with LiNixCo _y Al _z 02 with x+y+z = l, especially LiNi0.8Co0.15AI0 .05O2) as well as LiMn2Ü4 as spinel and LFP (LiFeP04), which is present in olivine structure.

In a preferred embodiment, the composition contains lithium or one of its compounds in an amount of 1 to 20% by weight, preferably 2 to 20% by weight, particularly preferably 2 to 15% by weight, in particular 3 to 15% by weight. % based on the total weight of the composition. Preferably the lithium is in the +1 oxidation state in the composition.

Also preferred is an embodiment in which the composition has at least one of the following elements in addition to lithium:

• Aluminum, preferably in the +111 oxidation state;

• cobalt, preferably in the +II and/or +III oxidation state;

• manganese, preferably in the +II and/or +III oxidation state;

• nickel, preferably in the +II and/or +III oxidation state; the elements being present in the form of their oxides and/or in the form of mixed oxides with one another.

In a preferred embodiment, the composition comprises at least 1% by weight, preferably at least 3% by weight, particularly preferably at least 8% by weight, of cobalt, preferably in the +III oxidation state, based on the total weight of the composition. In a preferred embodiment, the composition comprises at least 1% by weight, preferably at least 10% by weight, of nickel, more preferably at least 15% by weight, preferably in the +III oxidation state, based on the total weight of the composition.

In a preferred embodiment, the composition comprises at least 1% by weight, preferably at least 3% by weight, of manganese, particularly at least 8% by weight, preferably in the +III oxidation state, based on the total weight of the composition.

In particular, the composition used according to the invention contains or is obtained from at least one of the compounds selected from the group consisting of LiMO 2 layer structures with preferably M=Ni, Co, Mn and/or Al, in particular LiCo oxides (LCO), Li(Ni/Co) oxides (LNCO), Li(Ni/Co/Mn) oxides (LNCMO), Li(Ni/Co/Al) oxides (LN CAO), Li(Ni/Al) oxides ( LNAO), Li(Ni/Mn) oxides (LNMO), or LiM204 spinel structures with preferably M=Ni, Co and/or Mn, optionally with Al doping, or pure or doped LiFe phosphates, or any mixtures thereof .

The composition particularly preferably contains at least one of the compounds or is obtained from this, which is selected from the group consisting of LCOs, in particular UC0O2, NMCs, in particular LiNi _x Mn _y Coz02 with x + y + z = l, NCAs with LiNi _x Co _y Al _z 02 with x+y+z=l, especially LiNi0.8Co0.15AI0.05O2, as well as LiMn204 spinels and LFP, especially LiFeP04.

In a preferred embodiment, the composition also contains graphite, preferably in an amount of at most 60% by weight, particularly preferably at most 45% by weight, in particular 10 to 45% by weight, in particular 20 to 40% by weight, each based on the total weight of the composition.

In an alternatively preferred embodiment, the composition is essentially free of graphite, with the proportion of graphite in the composition preferably being less than 5% by weight, particularly preferably less than 2% by weight and in particular less than 1% by weight , each based on the total weight of the composition.

In battery technology, there is a large number of doping elements, which, depending on the intended use, extend across various elements of the main and subgroups of the periodic table. Therefore, an embodiment is preferred in which the composition also has doping elements, in particular those from the group of alkaline earth metals (magnesium, calcium, strontium, barium), scandium, yttrium, the titanium group (titanium, zirconium, hafnium), the vanadium group (vanadium, niobium, tantalum), the group of lanthanides or combinations thereof.

According to the invention, the composition is subjected to a washing step before the reductive treatment. In this way, not only can the electrolyte solution in particular be removed, but it has also been found that the amount of lithium recovered can be increased by this upstream washing step. An embodiment is therefore particularly preferred in which the method according to the invention provides the following steps in the order given: a) Washing a lithium(I)-containing composition, the lithium(I)-containing composition being obtained from used lithium-ion batteries will; b) heating the washed composition containing lithium(I) in the presence of a reducing agent, c) suspending the product obtained in step b) in an aqueous or organic suspension medium to obtain a solid reduction product and a solution containing lithium(I) and d) Separating the solid material to be reduced from the lithium(I)-containing solution

Water or an aqueous solution is preferably used as the washing medium for washing the lithium(I)-containing composition. A basic wash has proven to be particularly efficient. A basic aqueous solution is therefore preferably used, with the pH of the washing medium preferably being adjusted by adding a basic-reacting inorganic compound, preferably alkali metal and/or alkaline earth metal hydroxides and particularly preferably sodium hydroxide, lithium hydroxide or ammonia.

The washing medium preferably has a pH greater than 5, and the pH of the washing medium is particularly preferably from 5 to 14. The washing is preferably carried out at a temperature of from 10 to 120.degree. C., particularly preferably from 10 to 70.degree. In a likewise preferred embodiment, the washing is followed by a drying step, preferably at a temperature of 60 to 200.degree. C., particularly 80 to 150.degree. In a further preferred embodiment, the drying can be combined with the heating of the lithium(I)-containing composition in the presence of a reducing agent in step b).

In a preferred embodiment, the washed composition is essentially free, preferably free, of fluorine-containing compounds and/or phosphorus compounds. The content of fluorine-containing compounds in the composition is preferably less than 2% by weight, particularly preferably less than 1% by weight, in particular less than 0.5% by weight, based in each case on the total weight of the composition. In a further preferred embodiment, the content of phosphorus compounds in the composition is less than 0.2% by weight, preferably less than 0.1% by weight, based in each case on the total weight of the composition.

In a preferred embodiment, the composition is essentially free, preferably free, of non-aqueous, aprotic solvents commonly used in LIBs. These solvents can be, for example, ethylene carbonate, dimethyl carbonate or propylene carbonate. The content of these compounds in the composition is preferably less than 5% by weight, particularly preferably less than 2% by weight, in particular less than 0.5% by weight, especially less than 0.1% by weight. each based on the total weight of the composition.

Within the scope of the method according to the invention, the lithium(I)-containing composition can be subjected to further treatments which can be carried out, for example, before the washing step, after it or in combination with it. In this way, for example, electrolyte residues or graphite residues can be removed. This treatment preferably involves heating, drying, crushing, grinding, sorting, sieving, classifying, oxidizing, sedimenting, flotation and filtering or combinations thereof.

In a further preferred embodiment, such a treatment consists of an oxidative treatment. In this way, graphite contained in the composition in particular can be removed. Alternatively or additionally, graphite can also be removed from the composition by flotation and/or sedimentation be separated. A further embodiment is therefore preferred in which the method according to the invention comprises flotation and/or sedimentation, which preferably precedes the washing or can be combined with it. In this case, an embodiment is particularly preferred in which the sedimentation, ie the separation of graphite and cathode active material, is carried out using a heavy liquid with a density which is between the graphite to be separated and the cathode active material, with the cathode active material sedimenting and the Graphite can be skimmed from the surface of the dense liquid. The dense liquid is preferably selected from the group of tungstate solutions.

The composition is preferably in powder form. In order to achieve a desired particle size, the composition can be ground, the grinding preferably taking place before the washing step a) of the process according to the invention. Accordingly, an embodiment is preferred in which the composition is ground, preferably to a particle size of less than 200 µm, more preferably less than 100 µm, as determined according to ASTM B822.

In the process of the invention, the composition is heated in the presence of a reducing agent. The reduction is preferably carried out in an oven suitable for wet, dry or pre-dried materials. This furnace is preferably a static or moving bed furnace. As a suitable furnace for the thermal treatment, one is particularly preferred that is selected from the group consisting of rotary tube furnaces, fluidized bed furnaces, deck furnaces, roller hearth furnaces, tunnel furnaces, hearth furnaces, converters, pusher furnaces and belt furnaces.

In a preferred embodiment, the reduction is carried out in a rotary kiln.

In an alternative preferred embodiment, the reduction is carried out in a fluidized bed furnace.

In an alternative preferred embodiment, the reduction is carried out in a multiple-hearth furnace.

In an alternative preferred embodiment, the reduction is carried out in a roller hearth furnace. In an alternative preferred embodiment, the reduction is carried out in a belt furnace.

In an alternative preferred embodiment, the reduction is carried out in a tunnel kiln.

In an alternative preferred embodiment, the reduction is carried out in a hearth furnace.

In an alternative preferred embodiment, the reduction is carried out in a converter.

The furnace can be operated continuously or in batch mode.

In the context of the process according to the invention, it has proven to be advantageous to carry out the reduction at not more than 1000.degree. An embodiment is therefore preferred in which the reduction is carried out at temperatures of 300° C. to 1200° C., preferably 350° C. to 600° C., particularly preferably 350° C. to 450° C.

In particular, reducing gases can be used as reducing agents. In a preferred embodiment, the reducing agent is selected from the group consisting of hydrogen, carbon monoxide, carbon, methane, SO2, NH3 and chemically compatible mixtures thereof.

Hydrogen has proven to be particularly effective, so that an embodiment in which the reducing agent is hydrogen is particularly preferred. The reduction can be carried out in a hydrogen atmosphere, the proportion of hydrogen preferably being from 0.1 to 100% by volume, based on the atmosphere. In a preferred embodiment, the atmosphere comprises at least 50% by volume, in particular at least 80% by volume, in particular at least 90% by volume, hydrogen, the other gases preferably being those selected from the group consisting of nitrogen , argon, water vapor, carbon monoxide, carbon dioxide and mixtures thereof. In a particularly preferred embodiment, step b) of the process according to the invention is carried out in a rotary kiln or multiple-hearth furnace using hydrogen as the reducing agent.

In an alternative preferred embodiment, carbon monoxide (CO) is used as the reducing agent. In an alternative preferred embodiment, the reducing agent

Sulfur dioxide (SO2) used.

In an alternative preferred embodiment, the reducing agent

Ammonia (NH3) used.

In an alternative preferred embodiment, the reducing agent

carbon used.

In an alternative preferred embodiment, methane is used as the reducing agent.

In an alternatively preferred embodiment, the reducing agent is generated in situ. This is particularly preferred in cases where the

Composition contains graphite. In this way, carbon monoxide can then be generated in situ as a reducing agent, for example by introducing oxygen.

By reducing the composition according to the invention, the lithium from the lithium compounds contained in the composition is effectively converted into compounds soluble in the suspension medium, while other components of the LIBs such as nickel, manganese and cobalt remain in the solid reduction material as insoluble components.

The product obtained after the reductive treatment in step b) of the process according to the invention is converted into a suspension in a next step, an organic or aqueous suspension medium being used. Alcohols are particularly preferred as the organic suspension medium. Water is particularly preferably used.

According to the process according to the invention, a solid material to be reduced and a lithium(I)-containing solution are obtained, which can be further processed separately from one another in the further course. Therefore, the method according to the invention further comprises a separation step in which a liquid phase containing lithium dissolved therein and a solid filtration residue are obtained.

The separation step is preferably a filtration, centrifugation or a process based on sedimentation, in which a liquid phase containing lithium dissolved therein and a solid residue are obtained.

In a preferred embodiment, the solid material to be reduced contains one or more of the compounds selected from the group consisting of nickel metal, cobalt metal, Ni(II) compounds, Co(II) compounds and/or Mn(II) compounds, where additionally aluminum oxide and/or

Aluminum hydroxide may be included.

On the one hand, the method according to the invention offers the advantage that the lithium compounds can be further processed separately from the remaining residue, so that relatively high concentrations of the lithium-containing compound can be achieved, which means that on the one hand the recovery of the lithium can be operated very economically and on the other hand the lithium is not carried over through the entire subsequent process steps for cleaning and separating the residue.

The separate processing of the liquid phase and the residue is discussed in more detail below. i) liquid phase

The lithium is preferably present in the liquid phase in the form of a water-soluble compound, in particular in a form selected from the group consisting of lithium hydroxide, lithium hydrogen carbonate and lithium sulfate.

Depending on the composition used and the process control, the liquid phase can also contain soluble aluminum compounds in addition to the lithium compounds. An embodiment is therefore preferred in which the liquid phase also contains aluminum compounds.

In a preferred embodiment, the liquid phase is subjected to a further treatment to isolate the lithium. In this case, the lithium is preferably extracted from the liquid phase by precipitation, preferably by means of carbonation. The carbonation is preferably carried out by reaction with Na2CÜ3 or CO2.

Any aluminum compounds present in the liquid phase are preferably precipitated in the form of aluminum hydroxide by appropriate adjustment of the pH. In a preferred embodiment, lithium and aluminum dissolved in the liquid phase are separated from one another by treatment with CO2.

In a preferred embodiment, the lithium is present at least partially in the form of its hydroxide and any aluminum present as lithium aluminate. In these cases lithium and aluminum are preferably separated by treating the liquid phase with CO2. In this way, with suitable process management, the aluminum can be precipitated in the form of aluminum hydroxide in a first step, while the lithium remains in solution in the form of lithium bicarbonate. This can then be isolated in a subsequent step in the form of lithium carbonate. Surprisingly, the separation could be carried out in this way without significant losses of U2CO3 being observed.

In an alternative preferred embodiment, the lithium is present at least partially in the form of a salt of a mineral acid, preferably as a sulfate, and any aluminum present as Al 2 (SO 4 ) 3 . In these cases, the aluminum is preferably first precipitated as Al(OH) 3 by partial neutralization or appropriate adjustment of the pH, then separated and washed and in this way separated from the lithium. ii) solid residue

In particular, the elements cobalt, nickel, manganese and possibly aluminum remain as a solid residue. Therefore, an embodiment is preferred in which the residue contains one or more of the elements selected from the group consisting of nickel, cobalt, manganese, their alloys, their oxides and their hydroxides and mixtures thereof, the elements also in the form of Mixed oxides or mixed hydroxides may be present.

In order to isolate the elements remaining in the residue, in a preferred embodiment the residue is subjected to further separation processes in order to separate it into its components. Further processing depends on the form in which the elements are present in the residue, with different processes being able to be combined with one another. The person skilled in the art is aware that the remainder is not limited to the embodiments described below and these are available to the person skilled in the art are only intended to provide an advantageous teaching on how the elements nickel, cobalt, manganese and, if necessary, aluminum remaining in the residue can be extracted.

In a preferred embodiment, the residue contains one or more of the elements selected from the group consisting of nickel, cobalt, manganese, their alloys, their oxides, their hydroxides or mixtures thereof.

In a preferred embodiment, the residue comprises:

• nickel in the oxidation state +11 and/or 0, particularly preferably in the oxidation state 0;

• cobalt in the oxidation state +11 and/or 0, particularly preferably in the oxidation state 0;

• Manganese in the +11 oxidation state

• optionally aluminum in the +III oxidation state.

In a further preferred embodiment, the residue preferably contains less than 5% by weight lithium, particularly preferably less than 1% by weight lithium and in particular less than 0.5% by weight lithium and very particularly less than 0.1% by weight. -% lithium, each based on the total weight of the residue.

In a particularly preferred embodiment, the residue contains or consists of nickel and cobalt in metallic form and manganese in the form of its oxide and/or hydroxide.

In a preferred embodiment, the residue is further processed using at least one of the methods selected from the group consisting of treatment with mineral acids, magnetic separation methods, sedimentation, filtration, solvent extraction or pH-controlled precipitation.

In a preferred embodiment, the method according to the invention manages without a solid-solid separation step for separating nickel and/or cobalt from the filter residue.

Furthermore, it has proven advantageous to treat the residue with mineral acids. In this way, the elements can be dissolved in the form of their corresponding salts and thus extracted. In the case of the mineral acids it is preferably hydrochloric acid or sulfuric acid. Therefore, an embodiment is preferred in which the filtration residue is treated with mineral acids. Aluminum can be precipitated and separated from the solution obtained in this way in the form of its hydroxide by appropriate adjustment of the pH value, while the other elements nickel, cobalt and manganese remain in solution. The remaining elements can then be separated using solvent extraction, for example. Therefore, an embodiment is preferred in which the residue is treated with a mineral acid, the solution obtained is preferably adjusted to a pH of 2 to 5, in particular 3 to 4, in order to precipitate aluminum in the form of its hydroxide, the precipitate obtained is separated and the remaining liquid phase is subjected to solvent extraction.

In an alternative preferred embodiment, the liquid phase obtained is further treated with an oxidizing agent, preferably H2O2, taking the pH into account. In this way, the manganese contained in the liquid phase can be separated, while the elements nickel and cobalt remain in solution. The elements nickel and cobalt remaining after the manganese has been separated can be separated by further steps and used to produce pure nickel and cobalt compounds or to precipitate hydroxide or carbonate precursors for the production of cathode material for lithium batteries, in particular LIBs. Therefore, an embodiment is preferred in which the residue is treated with a mineral acid, the solution obtained is preferably adjusted to a pH of 2 to 5, in particular 3 to 4, in order to precipitate aluminum in the form of its hydroxide, the precipitate obtained is separated and the remaining liquid phase is treated with an oxidizing agent, preferably H2O2, while maintaining the pH, to separate manganese, the resulting precipitate is separated and the remaining liquid phase is further processed for further separation of nickel and cobalt.

For cases in which the elements nickel and cobalt are present in the residue in their metallic form and manganese and aluminum in the form of their oxides and/or hydroxides, it has proven to be advantageous to convert the residue into a preferably aqueous suspension, from which the elements nickel and cobalt are separated in metallic form from the Al and Mn-containing solution. The ones in solution remaining elements manganese and aluminum can then be extracted by known methods. Therefore, an embodiment is preferred in which the residue is converted into a preferably aqueous suspension by treatment with mineral acid and the elements nickel and cobalt remain in metallic form in the filtration residue, which are then also completely dissolved in mineral acids under more acidic conditions.

Where aluminum is present in the residue in the form of its hydroxide, it has been found advantageous to extract the aluminum by caustic leaching and separate the metals. Therefore, an embodiment in which the residue is subjected to alkaline leaching is preferred.

With the method according to the invention, lithium is obtained in the form of its salt or hydroxide, which can be present in highly concentrated solutions. Correspondingly, the lithium obtained by means of the method according to the invention can be fed into the material cycle for further use. A further object of the present invention is therefore the use of the lithium obtained according to the invention in the production of lithium batteries, rechargeable lithium batteries and lithium accumulators, rechargeable lithium-ion batteries and lithium-ion accumulators and/or rechargeable lithium-polymer batteries and lithium polymer storage batteries and other lithium containing electrochemical cells.

The use of the lithium obtained by means of the process according to the invention for the production of lithium metal and/or lithium oxide is also preferred.

Another preferred use of the lithium obtained by the process according to the invention is its use in the glass and ceramics industry, as a melting additive in aluminum production and/or as a flux in enamel production and in the production of antidepressants.

The present invention is intended to be clarified with the aid of the following examples and the following figures, which are in no way to be understood as limiting the idea of the invention.

In the context of the following examples, the following analytical methods were used as indicated: Inductively coupled plasma optical emission spectrometry: Li pyrohydrolysis, potentiometry: F combustion analysis: C carrier gas hot extraction: 0

X-ray fluorescence analysis: Al, Co, Cu, Fe, Mn, Ni, P Example 1:

1000 g of an exemplary LiNii _/3 Coi _/3 Mni _/3 O2 metallurgical composition in powder form were heated in the presence of hydrogen in a furnace. After the end of the reaction, the material to be reduced was cooled and suspended in water. The suspension was stirred until lithium was completely in solution. The results are summarized in Table 1. For comparison, the values given in the right-hand column “conventional” in Table 1 were obtained using a conventional method, as shown, for example, in FIG , Co, Mn.

Table 1 The comparison in the table shows the clear improvement that the method according to the invention achieves compared to the conventional methods. It can thus be clearly seen that, according to the conventional method, the transition metals are in solution together with lithium, while the method according to the invention allows the transition metals to be separated off in the form of solids, while lithium remains in solution. Furthermore, the table shows the increased Li concentration that is achieved with the method according to the invention. In the conventional method, the Li-

Concentration lower by a factor of 6.4 and naturally the

Transition metals according to the starting compound in relation to Li in the molar ratio of 1 to 1 before.

Example 2:

Step a) Washing

500 g of a black mass with the composition

Li (3.21 wt%), Al (1.02 wt%), Co (3.34 wt%), Cu (1.27 wt%), Fe (<0.1 wt%), Mn (1.95 wt%), Ni (20.6 wt%), P (0.24 wt%), F (2.41 wt%), O (19.2 wt%), C (46.84 wt%) based on that

total weight of the composition were slurried in 1 L of deionized water with stirring for 30 minutes, filtered and dried at 80°C. In this way, 450.9 g of dried, washed black mass was obtained.

Step b) Reductive treatment

40 g of the washed black pulp obtained in step a) were placed in an Alsint boat in a tube furnace and, after flushing with nitrogen, heated to 400° C. under a stream of pure hydrogen (240 L/h). The temperature was kept constant for 360 minutes and then the furnace was switched off

Hydrogen flow allowed to cool to RT. 36.8 g of material to be reduced were obtained.

Step c) Suspend

20 g of the reduction material obtained in step b) were suspended in 50 ml of deionized water with stirring. Step d) separating off the solid reduction material

The suspension obtained in step c) was filtered and the filtration residue was washed several times with a total of 450 ml of deionized water until the washing solution was no longer basic. 17.8 g of dry residue and 500 ml of filtrate solution were obtained, the residue containing 0.16% by weight of Li and the filtrate solution containing 0.67 g of Li. This corresponds to a Li recovery of 95.9% based on the Li content in the residue or 96.0% based on the Li content in the filtrate solution, based on the original amount of lithium in the black mass used. The good agreement of the yields according to the two methods of determination verifies the analytical methods used and thereby confirms the effective recovery of lithium by the method according to the invention.

Example 3:

Step a) Washing

400 g of a black mass with the composition

Li (3.21 wt%), Al (1.02 wt%), Co (3.34 wt%), Cu (1.27 wt%), Fe (<0.1 wt%), Mn (1.95 wt%), Ni (20.6 wt%), P (0.24 wt%), F (2.41 wt%), O (19.2% by weight), C (46.84% by weight), based on the total weight of the composition, were dissolved in 3.3 L of sodium hydroxide solution with a concentration of 200 g/L at 50° C. with stirring heated and stirred at constant temperature for 2 hours. The black mass was then filtered, washed with 3.7 l of deionized water and dried at 50.degree. 366.1 g of dried, washed black pulp were obtained.

Step b) Reductive treatment

40 g of the washed black pulp obtained in step a) were placed in an Alsint boat in a tube furnace and, after flushing with nitrogen, heated to 400° C. under a stream of pure hydrogen (240 L/h). The temperature was kept constant for 360 minutes and the furnace was then allowed to cool to RT under hydrogen flow. 37.1 g of product were obtained.

Step c) Suspend 36 g of the product obtained in step b) were suspended in 100 mL of deionized water with stirring.

Step d) separating off the solid reduction material

The suspension obtained in step c) was filtered and the filtration residue was washed several times with a total of 1.9 L of deionized water until the washing solution was no longer basic. 32.4 g of dry residue and 2000 mL of filtrate solution were obtained, the residue containing 0.16% by weight of Li and the filtrate solution containing 1.24 g of Li. This corresponds to a Li recovery of 95.9% based on the Li content in the residue or 99.4% based on the Li content in the filtrate solution, based on the original amount of lithium in the black mass used. The good agreement of the yields according to the various methods of determination verifies the analytical methods used and thereby confirms the effective recovery of lithium by the process according to the invention.

Example 4 (comparative example):

40 g of a black mass having the composition

Li (3.21 wt%), Al (1.02 wt%), Co (3.34 wt%), Cu (1.27 wt%), Fe (<0.1 wt%), Mn (1.95 wt%), Ni (20.6 wt%), P (0.24 wt%), F (2.41 wt%), O (19.2 wt%), C (46.84 wt%) based on the total weight of the composition were heated under reducing conditions without prior washing.

To do this, the black mass was placed in an Alsint boat in a tube furnace and, after flushing with nitrogen, heated to 400 °C under a stream of pure hydrogen (240 b/h). The temperature was kept constant for 360 minutes and the furnace was then allowed to cool to RT under hydrogen flow. 34.5 g of product were obtained.

20 g of this product were suspended in 50 mL deionized water with stirring and the suspension obtained was filtered and the filtration residue was washed several times with a total of 450 mL deionized water until the washing solution was no longer basic. 18.1 g of dry residue and 500 mL of filtrate solution were obtained, the residue containing 1.08% by weight of Li and the filtrate solution containing 0.52 g of Li. This corresponds to a Li recovery of 73.8% according to the Li Content in the residue or 69.6% according to the Li content in the filtrate solution, based on the original amount of lithium in the black mass used. The good agreement of the yields verifies the analytical methods used.

As a comparison of the data of Examples 2 and 3 according to the invention with those of Comparative Example 4 shows, the yield of lithium recovered from the battery waste could be significantly increased by the method according to the invention. The method according to the invention thus represents an effective method for processing used LIBs and allows the valuable raw materials to be reintroduced into a sustainable material cycle.

Description of the figures:

Figure 1 shows the schematic sequence of a conventional

Separation process used in the processing of battery waste, in particular for the recovery of the elements cobalt, nickel, manganese and lithium. First, a metallurgical composition is dissolved by acidic digestion with H2SO4 and the elements are precipitated one after the other. As can be seen from the overview, the elements cobalt and nickel are extracted in a co-precipitation, followed by manganese and lithium. The disadvantage of the process is that lithium is the last element to be separated off and is therefore present as a disruptive element in the preceding precipitations.

Figure 2 shows the schematic sequence of a conventional

Separation process used in the processing of battery waste, in particular for the recovery of the elements cobalt, nickel, manganese and lithium. First, a metallurgical composition is dissolved by acidic digestion with H2SO4 and the elements manganese, cobalt and nickel are separated by successive solvent extractions. Here, too, lithium is first extracted from the residue of the preceding reactions, which leads to a significant loss of yield.

FIG. 3 shows a schematic overview of an exemplary embodiment of the method according to the invention, in which an exemplary composition, which is specified as representative of a washed black mass, is heated in an oven in the presence of hydrogen as a reducing agent. The material to be reduced is cooled and suspended in water. Through Filtration of the solid gives a residue I containing nickel, cobalt and manganese and a filtrate I containing the dissolved LiOH. This is precipitated in the form of its carbonate by adding CO2. After the lithium has been separated, the further processing and separation of nickel, cobalt and manganese can take place without any disruptive influences from the lithium.

The method according to the invention, as described in FIG. 3, offers various starting points at which the valuable materials can be fed back into the material cycle. For example, the lithium sulphate solution (filtrate II) can be electrolytically separated into LiOH lye and diluted sulfuric acid at a Li producer. The Li producer then recovers solid Li0H*H20 from the LiOH leachate for reuse in the manufacture of cathode materials, particularly NCA cathode materials, and returns the sulfuric acid to the transition metal processor. In this way, a sustainable cycle can be established.

FIG. 4 shows an exemplary processing of the aqueous filtrate obtained after the leaching, in which lithium is present in the form of its hydroxide and aluminum in the form of lithium aluminate (filtrate I), as is obtained, for example, in the process described in FIG. The filtrate I is admixed with a suitable amount of CO2 in deficit and the lithium carbonate formed is separated off (residue II), a filtrate II being obtained. By supplying further CO2, the lithium hydroxide and lithium aluminate remaining in the filtrate II are separated, with the addition being controlled in such a way that the aluminate precipitates in the form of its hydroxide and is then filtered off (residue III), while lithium remains in solution in the form of lithium hydrogen carbonate (filtrate III), which is converted into lithium carbonate by heating and is thus precipitated. The resulting CO2 can be fed back into the cycle. In this way, efficient and simple separation of lithium and aluminum from the filtrate I is achieved.

Figure 5 shows an alternative extraction of aluminum and lithium from the filtrate I obtained according to the invention. The filtrate I is treated with excess CO2, so that aluminum is precipitated in the form of its hydroxide (residue II), while the lithium is in the form of lithium hydrogen carbonate in solution remains (filtrate II). After the aluminum hydroxide is filtered off, the remaining solution can be heated, whereby the lithium bicarbonate in Lithium carbonate passes and fails. The resulting CO2 can be fed back into the cycle.

As the figures make clear, the method according to the invention offers a simple and sustainable way of recovering the various valuable substances from the active materials of used batteries. Complex handling of liquid metallic phases and slag is therefore no longer necessary.

Claims

patent claims

Claims 1. A method of recycling LIB materials, comprising the steps of: a) washing a lithium(I)-containing composition, wherein the lithium(I)-containing composition is recovered from used lithium-ion batteries; b) heating a lithium(I)-containing composition in the presence of a reducing agent, c) suspending the product obtained in step a) in an aqueous or organic suspension medium to obtain a solid reduction product and a lithium(I)-containing solution and d) separating of the solid reduction material from the lithium(I)-containing solution.

2. The method according to claim 1, characterized in that water or an aqueous solution is used as the washing medium in step a).

3. The method according to claim 2, characterized in that a basic aqueous solution is used.

4. The method according to claim 3, characterized in that the pH of the washing medium is adjusted by adding a basic inorganic compound, preferably alkali metal and/or alkaline earth metal hydroxides and particularly preferably sodium hydroxide, lithium hydroxide or ammonia.

5. The method according to at least one of the preceding claims, characterized in that step b) is carried out at a temperature of 300 to 1200 °C, preferably 400 to 700 °C.

6. The method according to at least one of the preceding claims, characterized in that the composition and/or the material to be reduced, in particular the material to be reduced, is in the form of a powder.

7. The method according to at least one of the preceding claims, characterized in that the composition of used LIBs, production waste and secondary yields in the production of LIBs accrue, in particular in the production of the electrode materials, is obtained or consists of these.

8. The method according to at least one of the preceding claims, characterized in that the composition is black paste.

9. The method according to at least one of the preceding claims, characterized in that the composition contains lithium in an amount of 1 to 20% by weight, preferably 2 to 20% by weight, particularly preferably 2 to 15% by weight, in particular 3 to 15% by weight based on the total weight of the composition.

10. The method according to at least one of the preceding claims, characterized in that the composition comprises at least one of

Contains compounds or, preferably by means of pyrolysis, is obtained from this, which is selected from the group consisting of UMO2- layer structures with preferably M = Ni, Co, Mn and / or Al, in particular LiCo oxides (LCO), Li (Ni /Co) oxides (LNCO), Li(Ni/Co/Mn) oxides (LNCMO), Li(Ni/Co/Al) oxides (LN CAO), Li(Ni/Al) oxides (LNAO), Li(Ni/Mn) oxides (LNMO) or LiM204 spinel structures with preferably M=Ni, Co and/or Mn, optionally with Al doping, or pure or doped LiFe phosphates, or any mixtures thereof.

11. The method according to at least one of the preceding claims, characterized in that the composition comprises at least one of

Compounds contains or is obtained from this, which is selected from the group consisting of LCOs, in particular UC0O2, NMCs, in particular LiNi _x Mn _y Co _z 02 with x+y+z=1, NCAs with LiNixCo _y Al _z 02 with x+ y+z=l, especially LiNi0.8Co0.15AI0.05O2 and LiMn204 spinels and LFP, especially LiFeP04.

12. Process according to at least one of the preceding claims, characterized in that the reduction is carried out in a static or moving bed furnace.

13. The method according to claim 12, characterized in that the reduction is carried out in a furnace which is selected from the group consisting of rotary kilns, fluidized bed furnaces, deck furnaces, Roller hearth furnaces, tunnel furnaces, hearth furnaces, pusher furnaces, converters and belt furnaces.

14. The method according to claim 12, characterized in that the reduction is carried out in a rotary kiln or deck oven.

15. The method according to at least one of the preceding claims, characterized in that the reducing agent is selected from the group consisting of hydrogen, carbon monoxide, carbon, methane, SO2, NH3 or mixtures thereof.

16. The method according to claim 15, characterized in that the

reducing agent is hydrogen.

17. The method according to claim 15, characterized in that the

Reducing agent is carbon monoxide (CO).

18. The method according to claim 15, characterized in that the

Reducing agent is sulfur dioxide (SO2).

19. The method according to claim 15, characterized in that the

Reducing agent is ammonia (NH3).

20. The method according to claim 15, characterized in that the

Reducing agent is carbon.

21. The method according to claim 15, characterized in that the

Reducing agent is methane.

22. The method according to at least one of the preceding claims, characterized in that the solid material to be reduced contains one or more of the compounds selected from the group consisting of nickel metal, cobalt metal, Ni(II) compounds, Co(II) compounds and /or Mn(II) compounds, in which case aluminum oxide and/or aluminum hydroxide can also be present.

23. The method according to at least one of the preceding claims, characterized in that the separation step d) is a filtration, centrifugation or a process based on sedimentation, in which a liquid phase containing lithium dissolved therein and a solid residue are obtained will.

24. The method according to claim 23, characterized in that the lithium is extracted from the liquid phase by means of precipitation, preferably by carbonation.

25. The method according to at least one of claims 23 or 24, characterized in that lithium and aluminum dissolved in the liquid phase are separated from one another by treatment with CO2.

26. The method according to at least one of claims 23 to 25, characterized in that the solid residue contains one or more of the elements selected from the group consisting of nickel, cobalt, manganese, their alloys, their oxides, their hydroxides or mixtures thereof, where the elements can also be present in the form of mixed oxides and mixed hydroxides.

27. The method according to at least one of claims 23 to 26, characterized in that the solid residue comprises:

• nickel in the oxidation state +II and/or 0, preferably in the oxidation state 0;

• cobalt in the oxidation state +II and/or 0, preferably in the oxidation state 0;

• Manganese in the +11 oxidation state;

• optionally aluminum in the +III oxidation state.

28. The method according to at least one of claims 23 to 27, characterized in that the residue contains or consists of nickel and cobalt in metallic form and manganese in the form of its oxide and/or hydroxide.

29. The method according to at least one of claims 23 to 28, characterized in that the residue is further processed using at least one of the methods selected from the group consisting of treatment with mineral acids, magnetic separation methods, sedimentation, filtration, solvent extraction or pH -Value controlled felling.

30. The method according to claim 29, characterized in that the residue is treated with a mineral acid, the solution obtained is preferably adjusted to a pH of 2 to 5, in particular 3 to 4, is adjusted to precipitate aluminum in the form of its hydroxide, the precipitate obtained is separated and the remaining liquid phase is subjected to solvent extraction.

31. The method according to claim 29, characterized in that the residue is treated with a mineral acid, the solution obtained is preferably adjusted to a pH of 2 to 5, in particular 3 to 4, to precipitate aluminum in the form of its hydroxide, the the precipitate obtained is separated and the liquid phase is treated with an oxidizing agent, preferably H2O2, while maintaining the pH value, in order to separate manganese, the precipitate obtained is separated and the liquid phase obtained is further processed for further separation of nickel and cobalt.

32. The method according to claim 23, characterized in that the

Residue is converted into a preferably aqueous suspension by treatment with mineral acid and the elements nickel and cobalt are separated in the form of their metals.

33. The method according to claim 23, characterized in that the

Residue is subjected to alkaline leaching.

34. Use of lithium obtained by a method according to claim 1 in the production of lithium batteries, rechargeable lithium batteries and lithium accumulators, rechargeable lithium ion batteries and lithium ion accumulators and/or rechargeable lithium polymer batteries and lithium -Polymer accumulators and other lithium-containing electrochemical cells.

35. Use according to claim 34, characterized in that the lithium is used to produce lithium metal and/or lithium oxide.

36. Use according to at least one of claims 34 or 35, characterized in that the lithium is used in the glass and ceramics industry, as a melting additive in aluminum production, as a flux in enamel production and/or in the production of antidepressants.