Loss-free method for producing cathode active material without the formation of wastewater

Abstract

The invention relates to a resource-saving method for producing alkali-metal-containing cathode active materials, which forgoes the use of additional, purified water through the use of condensate water from the precursors. The invention also relates to the purification of the alkali-metal-containing washing water that arises during the production of cathode active material. According to the invention, alkali-metal precursor recovered in the process is fed back to the production process.

Description

[0001] LOSS-FREE PROCESS FOR THE PRODUCTION OF CATHODE ACTIVE MATERIAL WITHOUT WASTEWATER

[0002] The invention relates to a resource-saving process for producing alkali-metal-containing cathode active materials, which uses condensate water from the precursors without the use of additional treated water. The invention further relates to a treatment of the alkali-metal-containing wash water produced during the production of cathode active material. According to the invention, recovered alkali-metal precursor is returned to the production process.

[0003] background

[0004] Electromobility is under heavy criticism due to the lack of sustainability in the production of electric batteries, particularly the cathode active material containing lithium ions. Both the extraction of lithium and the lack of closed-loop recycling and the limited available quantities of lithium in particular represent a major challenge for the manufacturing processes. The production of the cathode active material cannot be considered a "green technology" according to the current state of the art. Not only the high energy requirements, but also the high demand for lithium and other metal oxides such as nickel, cobalt, iron and manganese make the future of electromobility very questionable. This invention is therefore of particular importance for the future technology of electromobility.Electromobility only has a future by closing the cycle and preventing wastewater and waste from the production process. This invention enables waste- and wastewater-free production of cathode active material. Often, the discharge conditions at production sites and the limit values ​​to be observed for alkali metals (especially lithium), nickel, cobalt, manganese, sulfate, nitrate, phosphate, etc. are not at all feasible with the current state of technology. For this reason, evaporation plants are often used to concentrate the wastewater. The high energy consumption required for this is not consistent with the concept of sustainability.Further processing and recovery of alkali metal from the concentrate (bottom product) is also significantly more complex and cost-intensive than the alkali metal-containing solution obtained in this invention through optimized material flows.

[0005] The object of the present invention is therefore to provide a waste- and wastewater-free process for producing a cathode active material in which the raw materials end up exclusively in the product by closing the cycle and impurities (such as sulfate, nitrate, carbonate, etc.) are separated off and converted into a usable product. The losses of raw materials, in particular of alkali metals (e.g. lithium) and other metals contained in the precursors, are to be eliminated or at least reduced to a minimum and the generation of waste is to be excluded. A further aim of the present invention is that the entire production process can be carried out without additional water, in particular demineralized or deionized water.

[0006] Subject of the invention

[0007] The object is achieved by a method comprising the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0008] The invention provides a method for this purpose, comprising the steps: a) providing one or more metal compounds 7 in 3; b) providing an alkali metal compound 5 in 1; c) dewatering / drying the alkali metal compound 5 in device 9 and / or dewatering / drying the metal compounds 7 in device 11 and / or dewatering / drying the recovered alkali metal-rich product 60, preferably in device 63 or alternatively in device 9, separating the resulting condensates 15, 19 and 64, collecting them in the condensate container 55, passing the condensate mixture 43 into the wash water reservoir 47, using it as wash water 34 for the washing process and as wash water 38 for cleaning the filter unit 32; d) producing a metal oxide lattice and incorporating alkali metal with unit 24;e) Washing the CAM precursor 26 (alkali metal metal oxide lattice) obtained from step d) in device 28 with the wash water 34 from the receiver 47 from step c), solid / liquid separation of the washed CAM product 30 via a unit 32 and separation of a filtrate 42 and a solid 44; f) Cleaning the filter device 32 with the wash water 38 from the receiver 47 and returning the rinsing water 40 to the wash water receiver 47, keeping the alkali metal and acid residual anion concentration constant by removing alkali metal-rich material stream 48 from the wash water receiver 47 and volume compensation by supplying alkali metal-poor material stream 54 and / or condensate 46 and / or condensate 43;g) processing the alkali metal-containing material stream 48, 50, 52, 56 from step f) to obtain an alkali metal-rich material stream 60, dewatering the material stream 60 in unit 63 and recycling the recovered alkali metal precursor 62, preferably in the mixing device 21, back into the production process. In the process according to the invention, it is preferred that the wash water 48 from the receiver 47 from step f) is subjected to a solids separator 65, wherein the solids separation 65 can also be optional. The solids separator 65 preferably consists of a solids filter 49 (membrane filtration) with a filtrate collecting container 51 and / or a sedimentation 69 (e.g. inclined clarifier) ​​and / or a chamber filter press 73 (or decanter). The resulting "solids-free or low-solids solutions" 50 and / or 68 and / or 72 are preferably collected in collection tanks 51. Figure 4 shows the solids separator unit 65 with material flows.

[0009] According to an advantageous embodiment of the invention, the solids-free solution 52 is fed to a "concentration unit" 53 and / or a membrane separation process 61 (e.g., diffusion dialysis), wherein the resulting "alkali metal-poor solution" 54 from the concentration unit 53 is fed back to the wash water reservoir 47 and an alkali metal-enriched solution 56 is separated.

[0010] According to the invention, the alkali metal-rich solution 56 is subjected to a membrane separation process 61, whereby an alkali metal-rich / low-sulfate stream 60 is obtained. Preferably, the alkali metal-rich stream 60 is dewatered, and the dewatered alkali metal product 62 is dewatered from the alkali metal-containing precursor 1 or together with precursor 1 in 9. The condensate 64 is fed to the condensate collection tank 55, and from there the condensate mixture 43 is subsequently fed to the wash water collection tank 47. Depending on the product process or the additives used, the alkali metal-rich / low-sulfate stream 60 can be low in other acid residue anions, such as nitrate, carbonate, phosphate, etc., instead of low in sulfate. According to an advantageous embodiment of the invention, the filtration in step e) is carried out by means of a chamber filter press 32.The resulting solid-free filtrate 42b and the return flow 40 resulting from the cleaning of the chamber filter press filter cloths are fed to the washing water reservoir 47.

[0011] The alkali metal concentration in the wash water receiver 47 is kept constant during the process by discharging the material stream 48.

[0012] It is further preferred within the meaning of the process according to the invention that the respective material streams 43, 46, 54, 40 and 42b from the drying, dewatering, separation and filtration processes are cascaded into the wash water reservoir 47. The cascading is evident in Figure 3. The material streams with the lowest alkali metal concentrations—as expected, these are condensates 15, 19 and 64 or the condensate mixture 43 and the condensate 46—are introduced at the rearmost end of cascade 47.3, followed by material stream 54 in cascade 47.2, material streams 40 and 42b in cascade 47.1 and from there into the wash process reservoir 47.0. The wash water for streams 34, 38, and 48 is then taken directly or exclusively from 47.0, which has the highest alkali metal concentration. The cascading system can, for example, consist of individual tanks (47.3 => 47.2 => 47.1 => 47.0) connected to each other via pumps.However, any other type of cascading can also be used. This cascading ensures that the concentration is kept very constant when withdrawing from receiver 47.0 and prevents concentration fluctuations due to different feeds.

[0013] The process does not require any externally supplied water, distilled water, or deionized water. Therefore, according to a further advantageous embodiment of the invention, no external deionized water is supplied.

[0014] The precursor 7 used in the process according to the invention preferably consists of metal hydroxides comprising the metals Ni, Mn, Co, Al, Fe, Ti, Ta, Zr, Nb or other transition metals or lanthanides, or mixtures thereof, with combinations of Co, Ni, Fe, Mn with lithium (precursor 5) being most preferred.

[0015] The alkali metal compound 5 is preferably alkali metal hydroxide or alkali metal carbonate. Lithium is most preferred as lithium hydroxide monohydrate.

[0016] (LiOH*lH2O) , which has a hydration water content of approximately 43%. The proportion of Li + is only about 16.5%.

[0017] The additives 22 for the preparation of the alkali metal oxide compounds (especially lithium metal oxide) are preferably boric acid, aluminum sulfate, zirconium oxide, and aluminum hydroxide. However, other additives, such as sulfuric acid, sodium hydroxide, titanium dioxide, and others, can also be used.

[0018] In the process according to the invention, a membrane separation process also produces an anion-rich stream 58 and a low-acid anion / alkali metal-rich stream 60 for reuse or recycling of the production process. Stream 58 (acid) is preferably collected in the collection tank 59.

[0019] It is further preferred that the condensate water from collection tank 55 is used as feed 57 for the membrane separation process 61 (diffusion dialysis).

[0020] The use of the alkali metal-rich precursor 5, e.g. LiOH*lH2O, as starting material advantageously leads to the formation of a condensate 15 in the dewatering step 9, which is collected and reused for later washing steps.

[0021] Likewise, the dewatering in unit 11 of the preliminary product 7 produces a condensate 19 which, however, only makes up a small proportion of the condensates due to a significantly lower water content of only about 0.4% (depending on the product and quality). For the sake of completeness, the condensate 19 is also fed to the condensate tank 55 for further use as wash water. This thus enables, among other things, the use of other qualities with a higher water content. The anhydrous alkali metal oxide 13 from the dewatering / drying 9, the anhydrous Me oxide mixture 17 from the dewatering / drying 11 and preferably the addition of further additives 21 are preferably mixed homogeneously in a mixing device 21 (e.g. with a high-speed mixer). Anhydrous is understood to mean what is technically feasible and still economically sensible.Thus, the slightest traces of water are possible as long as they do not have a negative impact on the quality of the CAM product.

[0022] The homogeneous mixture 23 is subjected to a standard sequence of process steps 24 (calcination, deagglomeration, and sieving / magnetic separation). These steps are known to those skilled in the art.

[0023] The invention further relates to a processing plant for carrying out the method as described above. The same features apply to the processing plant as described for the method according to the invention. Particular reference is made to the list of reference symbols and Figures 1, 3, and 4.

[0024] The invention further relates to the use of the process plant as described above for producing an alkali metal-containing cathode active material. Yet another subject of the invention is the use of the process plant as described above for producing acids, such as sulfuric acid, phosphoric acid, nitric acid, or carbonic acid, although this list is not exhaustive and depends on the cathode active material to be produced or the additives used.

[0025] Detailed description of the invention

[0026] The positive electrode in the battery is often referred to as the "cathode." Most conventional lithium-ion batteries use lithium cobalt oxide as the cathode. However, in recent years, many alternative material systems have been developed and deployed.

[0027] Due to the high price and low availability of lithium, the further development of sodium-ion batteries

[0028] (NIB). Sodium-ion batteries have high growth potential due to their superior product properties. In contrast to the limited supply of lithium, the earth's crust consists of 2.6% sodium. A combination of lithium-ion and sodium-ion technology, the so-called hybrid battery, is also possible. The importance of NIB may well increase in the coming years, and the invention could also be used here and play a decisive role, although the savings with LIB are significantly higher.

[0029] In most cases, however, lithium and oxygen are still an essential component of the system. Only the metallic element cobalt is often completely or partially replaced by other metallic elements such as nickel and manganese. For this reason, most lithium-ion batteries can be described as a so-called lithium metal oxide cathode. However, systems are also known which use, for example, lithium iron phosphate as a material. Lithium metal oxides are produced as solid powders. When selecting the powder as a suitable material for use as a cathode in a lithium-ion battery (LIB), the microstructure, morphology, particle size and the degree and type of possible impurities in the powder play a crucial role. These influence the electrochemical properties of the battery that is subsequently made from it.

[0030] In particular, the energy density, which is of great importance for the range of electric vehicles, for example, is influenced by the structural parameters mentioned above.

[0031] The microstructure of the cathode must therefore be precisely tuned. This can be achieved, on the one hand, by the correct selection of raw materials and, on the other hand, by a controlled manufacturing process for cathode powders. As the term suggests, a lithium metal oxide is a solid solution of lithium oxide and oxides of other metals. These solid solutions are formed by thermally treating a mixture of the individual oxides at high temperatures, typically between 800 and 1000 °C under specific atmospheric conditions. The individual oxides, in turn, are provided by adding various raw materials to the mixture. The starting materials are often hydroxides or carbonates of lithium and the respective other metallic elements.

[0032] In the "Synthesis Report: Cathode Active Material for Lithium-Ion Batteries, Entry ID 506108 (status of knowledge as of June 14, 2023; https: / / www.forschungsinformationssystem.de / ), the advantages and disadvantages of the various cathode active materials (NMC, LFP, LCO, and LMNS) are compared. Due to the high importance of safety and service life with regard to battery use in electromobility, the layered oxide of lithium, nickel, manganese, and cobalt (NMC) is considered one of the suitable active materials for lithium-ion batteries. Depending on the materials and additives used, different cations (Li, Ni, Co, Mn, Fe, Al, etc.) and anions (sulfate, phosphate, carbonate, nitrate, etc.) can flow into the material. However, the principle of the invention is independent of this and applies to all variants of active materials. Instead of sulfuric acid, a different acid is then used. (phosphoric acid, nitric acid, carbonic acid, etc.) are recovered.

[0033] By heat treatment of these starting materials at temperatures of 600-800 °C, water (H2O) or carbon dioxide (CO2) is released; the remaining oxides later participate in a solid solution through further treatment.

[0034] Basically, in the production of the cathode, various oxides are obtained from the respective hydroxides or carbonates of the same elements in a first step and then, in a second step, the desired solid solution is produced from these oxides.

[0035] The first step, in which two solids react to form a third solid and gases are released, is called calcination. The second step is called sintering or solid diffusion. Calcination occurs almost independently of time as soon as the temperatures and starting materials required to start the reaction are available. Consequently, the first steps of the thermal treatment in cathode production are relatively quick. The diffusion processes for forming the solid solutions, on the other hand, are very time-dependent and take considerably longer. In the prior art, the two steps are usually carried out consecutively in one process; in others, however, the calcination products are first cooled and later sintered in a separate thermal process.

[0036] In addition to costs and production capacity in a small space, product quality is also one of the success factors for cathode powder manufacturers. At the same price, battery manufacturers naturally prefer materials with, for example, higher energy density. This can be achieved by optimally exploiting the thermodynamic influences on the calcination and sintering processes.

[0037] Figure 2 shows a simplified version of a typical manufacturing process (state of the art) for such cathode materials. Intermediate steps such as screening / magnetic separation and deagglomeration are not fully listed because the resulting small losses are negligible for the representation of the material flows.

[0038] The material flows shown in the block diagram, the closed loop, and in particular the use of condensates instead of pure demineralized water, eliminate the need for additional demineralized water. Instead of multiple wastewater flows with varying levels of contamination, there is only a single material flow with constant concentrations of dissolved ions (residual acid anions, alkali metal cations), which is reduced from 2.5-4 liters per kg of product (CAM - Cathode Active Material) to 0 liters per kg.

[0039] The major advantage over the conventional process is the high concentration of alkali metal (e.g. lithium), which makes recovery possible and economical.

[0040] Only through the recycling and reuse of the wash water, which is a component of the invention, can consistent product quality be achieved. A component of the invention is that the concentration of alkali metal (e.g., lithium) or alkali metal sulfate or other alkali metal compounds in the wash water reservoir 47 is kept constant. This is the only way to control the process. The resulting constant process conditions enable consistent product quality. This is possible for the first time with this invention.

[0041] By recirculating the wash water in reservoir 47 and maintaining a defined concentration of already dissolved alkali metal (e.g., lithium) in the wash water, the undesirable redissolution of the alkali metal (e.g., lithium) from the metal oxide lattice is avoided. The washing process 28 is intended solely to wash out excess alkali metal (e.g., lithium) not incorporated into the lattice. These problems are known in existing systems. A solution to this problem has not yet been found in the state of the art.

[0042] Re-dissolution of heavy metals (Ni, Co, Mn, Fe, etc.) is not expected due to the pH range of 10-12. Therefore, these are not taken into account in the quality of wash water reservoir 47.

[0043] The concentration in the wash water reservoir 47 is limited, among other things, by the solubility, in particular the solubility of alkali metals or alkali metal salts. In the example of lithium or lithium sulfate, Li2SO4 has a good solubility of 342 g / l at 25°C in water. This results in a maximum concentration of 43.18 g / l of dissolved lithium. The lithium concentration is also determined depending on product quality, formulations, precursors used, additives, and other process parameters. Using the example of the lithium-containing cathode active material NMC (lithium-nickel-manganese-cobalt) and the corresponding

[0044] Using LiOH*lH2O as precursor 5 and Ni-Mn-Co hydroxide mixture as precursor 7, the concentration is preferably defined as 23 to 25 g / l lithium in the wash water.

[0045] The defined concentration of lithium or other alkali metals in the wash water reservoir 47 is also determined taking into account the technical and economic operation of the subsequent processes for treating the solution and recovering the raw materials, in particular lithium (sulfate).

[0046] A component of the invention is, among other things, that a solids separation 65 is used to separate possible solids from the discharged wash water 48 upstream of the downstream membrane processes 53 and 61 for the recovery / concentration of alkali metal compounds. The solids separation 65 is shown in Fig. 4 with the possible or combinable process steps. Here, among other things, an ultrafiltration 49 can be used to separate possible solid particles, the resulting concentrate 36 can be collected in the concentrate container 37, and the material stream 36a can subsequently be fed back to the CAM product 30. This is preferably carried out by proportional mixing with the washed CAM product 30 upstream of the unit 32. The proportional mixing can, however, also take place directly in the unit 28 in which the washing process takes place. This guarantees that by returning the concentrate 36a to the production process, no losses of product, alkali metal (e.g.Lithium), etc. and therefore no additional.

[0047] Waste streams are generated. Other solid / liquid separation processes can also be used, such as solids separation by sedimentation 69 (e.g., using inclined or lamella clarifiers), decanters and / or filter presses 73, or other depth and surface filtration processes. A combination of different solid / liquid separation processes is also possible. The resulting solids 74 are mixed with solids 44 in the collection tank 33 and collected.

[0048] The invention primarily relates to the material flow and the recirculation of the concentrate 36a into the process. The recirculation of the solids-rich material flow 36a preferably occurs by proportional mixing with feed 30, either directly in or before unit 32. Recirculation and mixing in washing device 28, in which the washing process takes place, is also conceivable.

[0049] Depending on which alkali metal concentration in the wash water reservoir 47 is deemed appropriate or necessary, subsequent concentration can be carried out, e.g., by means of nanofiltration 53. The alkali metal-poor solution 54 (filtrate) generated from the nanofiltration is returned to the wash water reservoir 47. The concentration of alkali metal salt (e.g., lithium sulfate) in the reservoir 47 is kept constant by discharging the alkali metal salt-enriched solution 48 (concentrate) (e.g., lithium sulfate).

[0050] The material streams "Rinse water filter cloth cleaning" 40, "Filtrate solid / liquid separation" 42b, "Low alkali metal solution" 54, Condensate 15, Condensate 19, Condensate 46 and Condensate 64 can also be collected separately.

[0051] A variant of the invention provides for a cascaded combination of the individual material streams, as shown in Figure 3. The individual material streams are fed to the respective cascade stage depending on their purity and volume. With this variant of the wash water reservoir 47, concentration fluctuations in the water inlet 34 and 38 are avoided, which makes it possible to operate the washing process 28 within a very narrow tolerance range. The constant concentration in the wash water reservoir also brings advantages in the subsequent processing of the material stream 48 or 52. The amount of condensate 19 from the drying / dewatering 11 of the precursor 7 is so small that it can actually be neglected. However, for the sake of completeness, this has been included in the invention because there are many different precursors with different components, different purities and also different water contents.

[0052] Part of the invention is that the concentrate 56 from the nanofiltration 53 is fed to a membrane separation process 61 (e.g. a diffusion dialysis), wherein the material stream 48 from the receiver 47 can also be fed directly to a membrane separation process or to the diffusion dialysis 61, without prior concentration or without prior nanofiltration 53.

[0053] A semipermeable anion exchange membrane is preferably used (acid diffusion dialysis). This membrane allows the H + - and the S04 2“-Ions or acid residue anions diffuse and the alkali metal ions (e.g. lithium) are retained. This results in acid 58 being recovered in the diffusate, which is used elsewhere as a raw material. The amount of acid produced preferably corresponds approximately to the amount of condensates 15 and 19 produced, which results from the volume balance. In the dialysate, we recover an alkali metal-rich solution 60 (e.g. LiOH*xH2O). This alkali metal-rich material stream 60 is preferably dewatered using a separate unit 63, and the recovered alkali metal-rich and anhydrous precursor 62 is mixed in the desired mixing ratio with the substances 13, 17 and 22 in the mixing unit 21. The dewatering unit 63 preferably includes, among other things, a collecting tank as a receiver before drying.However, the proportional mixing (blending) and dewatering can also be carried out in the dewatering unit 9, together with the precursor product 5 or separately, provided that the higher water content during mixing does not cause any problems.

[0054] A further component of the invention is that the deionized water required for the membrane separation process 61 (e.g., diffusion dialysis) is preferably replaced by the condensate water 57 (15, 19, 64) from the collection tank 55, thus eliminating the need for additional deionized water. The deionized water required for diffusion dialysis can also be partially replaced or mixed with condensate water.

[0055] The invention will now be explained in more detail with reference to Figure 1. The figures show:

[0056] Figure 1: A block flow diagram of the material flows in a CAM manufacturing process according to the invention;

[0057] Figure 2: A block flow diagram of the material flows in a CAM manufacturing process according to the state of the art;

[0058] Figure 3: Variant of wash water reservoir 47 cascaded, whereby the material streams with the lowest alkali metal concentrations 15, 19 and 64 or the condensate mixture 43 and the condensate 46 are arranged at the rearmost end of the cascade 47.3, followed by material stream 54 in cascade 47.2, then the material streams 40 and 42b in cascade 47.1 and from there into the wash process reservoir 47.0;

[0059] Figure 4: Option / variant solids separation 65, comprising solids filter 49, and / or filtrate collection container 51 and / or sedimentation 69 and / or decanter and / or chamber filter press 73 and / or concentrate collection container 37 List of reference symbols

[0060] 1 - Storage tank for alkali metal-containing precursor 5

[0061] 3 - Pre-product storage container 7

[0062] 5 - Alkali metal precursor

[0063] 7 - Metal oxide mixture precursor

[0064] 9 - Dewatering / drying device for precursor product 5

[0065] 11 - Dewatering / drying device for precursor product 7

[0066] 13 - Anhydrous alkali metal oxide

[0067] 15 - Condensate from drying / dewatering precursor 5

[0068] 17 - Anhydrous metal oxide mixture

[0069] 19 - Condensate from drying / dewatering precursor 7

[0070] 21 - Mixing unit

[0071] 22 - Template Additives

[0072] 23 - Homogeneous mixture

[0073] 24 - Generation of Me oxide lattice and Li intercalation via calcination, deagglomeration, sieving / magnetic separation

[0074] 26 - CAM pre-product

[0075] 28 - Washing device CAM product

[0076] 30 - CAM product, washed

[0077] 32 - Device for solid / liquid separation

[0078] 33 - Solids collection container CAM

[0079] 34 - Washing water

[0080] 36 - Solids-rich solution (concentrate)

[0081] 36x - a=recirculation, b=further concentration

[0082] 37 - Collection container concentrate / solids

[0083] 38 - Wash water for filter cleaning

[0084] 40 - Rinse water filter cleaning

[0085] 42 - Filtrate solid / liquid separation (a=turbidity, b=clear)

[0086] 43 - Condensate mixture

[0087] 44 - Solid (e.g. filter cake, CAM product for drying)

[0088] 45 - Drying / dewatering unit (e.g. filter cake) - Condensate from drying 45

[0089] - Wash water reservoir - Example of cascaded wash water reservoir 47.0 to 47.3

[0090] - Feed solids filter (e.g. ultrafiltration)

[0091] - Solids filter (e.g. ultrafiltration)

[0092] - Solid-free or low-solids solution (permeate)

[0093] - Filtrate collection tank

[0094] - Solid-free solution (Feed 53)

[0095] - On concentration unit

[0096] - Low-alkali metal solution

[0097] - Condensate collection tank

[0098] - Alkali metal-rich solution from concentration unit

[0099] - Condensate water

[0100] - Anion-rich stream (acid)

[0101] - Acid container

[0102] - Alkali metal-rich material stream

[0103] - Membrane separation processes (e.g. diffusion dialysis)

[0104] - Recovered alkali metal-rich precursor

[0105] - Drainage unit

[0106] - Condensate from drainage

[0107] - Solids separator

[0108] - Clear phase, low in solids

[0109] - Sedimentation (e.g. lamella clarifier)

[0110] - Sediment, solids rich

[0111] - Solids-free or low-solids solution from solids filter

[0112] - Solid / liquid separation (e.g. KFP and / or decanter)

[0113] - Solids (e.g. filter cake) from unit 73 Description of the process:

[0114] Condensate 15 from dewatering 9 of precursor 5, condensate 19 from dewatering 11 of precursor 7, and condensate 64 from dewatering 63 of alkali metal-rich stream 60 from the process are collected in tank 55 and (re)used as a feedstock for the washing process. The majority of the condensate comes from the drying of precursor 5, and a small portion from the drying of precursor 7.

[0115] After the CAM precursor 26 (e.g., Li-metal oxides or Li-metal oxide mixture) has been produced, the reaction product is washed and filtered. Filtration is preferably carried out in a chamber filter press 32 through a filter cloth, although any other filtering methods known to those skilled in the art can also be used. The filtrate 42b from the chamber filter press 32 or the wash water 38 from the wash water reservoir 47 is used to clean the filter cloth. This prevents or reduces redissolution of alkali metal at the filter cloth / CAM product interface.

[0116] The water flows of the condensates 15, 19 and 64 are collected in the condensate collecting tank 55, the filtrate 42 from the chamber filter press and the rinse water return 40 from the cloth wash are collected in the storage tank 47.

[0117] The filtrate 42 from the chamber filter press is initially circulated (material flow 42a) to prevent filtrate contaminated with solids from entering the wash water reservoir at the beginning (filter cake buildup, turbidity run). The switchover to the wash water reservoir can also be monitored and controlled by sensors (turbidity).

[0118] The concentration of alkali metal (e.g., lithium, sodium, etc.) and residual acid anion (e.g., sulfate, phosphate, etc.) in the wash water reservoir 47 is kept nearly constant. As expected, when using LiOH*lH2O as precursor 5, the lithium concentration will be 23-28 g / l. This lithium concentration range has a positive effect on the wash process because it significantly reduces the undesirable re-dissolution of lithium.

[0119] Ideally, a value of around 25 g / L should be achieved.

[0120] Subsequent processing and recovery of lithium or other alkali metals are facilitated by the high concentration, e.g. of lithium or sodium, in the receiver 47.

[0121] Further concentration 53 of the resulting alkali metal-containing solution can preferably be carried out by nanofiltration or diffusion dialysis. A combination of nanofiltration and diffusion dialysis is preferred.

[0122] To avoid contamination of nanofiltration or diffusion dialysis with solid particles, a solids separation 65 is installed upstream. This solids separation can include microfiltration and / or ultrafiltration as well as other solids separation processes.

[0123] Further processing of the lithium sulfate to obtain lithium oxide monohydrate can be carried out, for example, as described in EP 2 762 611.

[0124] The solids-rich solution 36 from the solids filter 49 (e.g., microfiltration or ultrafiltration) can preferably be further concentrated as stream 36b in subsequent steps, e.g., sedimentation 69 using a lamella clarifier or simply in a thickener and subsequent chamber filter press (KFP) or decanter 73 (Fig. 4). The solids (e.g., filter cake) 74 can also be delivered as a product according to customer specifications, e.g., by blending (mixing off-spec with product). Preferably, however, the solids-rich concentrate 36 from the solids separator 65 is collected in container 37 and mixed proportionally with feed 30 as feed 36a in device 32.

[0125] The process can also be carried out in stages. Since the remaining volume is very small, the recovery of alkali metals, especially lithium, for example, as lithium hydroxide monohydrate or other lithium or alkali metal compounds, can also be carried out off-site.

[0126] The process, especially the material flows, is the true invention, enabling a closed-loop process in the production of cathode active material, resulting in virtually no losses. Additional resources such as deionized water, raw materials, and chemicals for pH adjustment are unnecessary.

[0127] The recipe and precursors used may differ from the variant shown. The additives, as well as the precursors, vary depending on customer requirements.

[0128] The invention offers the following advantages:

[0129] • Consistent and very high product quality

[0130] • Controlled process (sensitivity of the washing process according to the current state of the art is no longer given).

[0131] • No additional need for resources (water, chemicals for wastewater treatment, etc.)

[0132] • 100% of the raw materials used end up in the product. No raw material losses.

[0133] • No waste, wastewater or sludge is produced.

[0134] • Elimination of high investment costs for equipment, such as evaporation plants for concentrating wastewater enriched with lithium (e.g.).

[0135] • Elimination of the discharge of wastewater and therefore no conflict with discharge limits.

[0136] Cost savings resulting from the invention:

[0137] A. Recovery of the alkali metal (especially lithium) or the precursors by closing the cycle

[0138] B. Elimination of wastewater treatment plants or other plants, such as evaporation plants

[0139] C. No costs for treatment and discharge of wastewater

[0140] D. No costs for disposal of waste / concentrates

[0141] E. Extraction of raw material acid (e.g. sulfuric acid)

[0142] F. Demand for demineralized water is eliminated 100%

[0143] G. No additional costs for acids and alkalis for pH adjustment

[0144] H. Based on 2023 prices for raw materials, etc., a saving of approximately €2,000 per ton of CAM product will be achieved compared to the state of the art.

[0145] Using the example of lithium cathode active material, the listed points result in an expected total saving of approximately €2,000 per ton of CAM, with the highest saving being achieved by point A and subsequently point B.

Claims

AMENDED CLAIMS received by the International Bureau on 05 September 2024 (05.09.2024) 1. A process for producing an alkali metal-containing cathode material, comprising the steps: a) providing one or more metal compounds (7) in (3); b) providing an alkali metal compound (5) in (1); c) dewatering / drying the alkali metal compound (5) in unit (9) and dewatering the metal compounds (7) in unit (11) and dewatering / drying the recovered alkali metal-rich product (60), preferably in unit (63) or alternatively in unit (9), collecting the resulting condensates (15) and / or (19) and / or (64) in the condensate container (55) as a mixture (43) or separately; d) mixing (13), (17) and / or recovered alkali metal-rich precursor (62) and / or further additives (22) in the mixing device (21) in the desired mixing ratio to form a homogeneous mixture (23);e) producing the CAM precursor (26) by generating a metal oxide lattice and incorporating alkali metal with the mixture (23) obtained from d) in the unit for calcining, deagglomerating and screening (24); f) passing the condensate mixture (43) from c) or condensate (15) and / or (19) and / or (64) into the wash water receiver (47); g) washing the CAM precursor (26) obtained from step e) in device (28) with the wash water (34); Template (47) from step f) and obtaining CAM product washed (30); h) solid / liquid separation of the washed CAM product (30) from g) via a unit (32) and separation of a filtrate (42) and a solid (44); i) collecting the solid (44) from h) in container (33) and returning the filtrate (42b) to the wash water template (47); j) drying the solid (44) from i) in unit (45) and 27 AMENDED SHEET (ARTICLE 19) Returning the condensate (46) to the receiver (47); k) Cleaning the filter device (32) with the wash water (38) from the receiver (47) from step f) and returning the rinsing water (40) to the wash water receiver (47); l) Maintaining the alkali metal and residual acid anion concentration in the wash water (34) and (38) constant by removing the alkali metal-rich material stream (48) from the wash water receiver (47) and equalizing the volume by adding the alkali metal-poor material stream (54) and / or condensate (46) and / or (condensate) mixture (43); m) Separating any solids in the material stream (48) from step 1) with unit (65), obtaining the material streams solid (74) and / or solid-rich (36a) and solid-free (52), wherein the solids separation (65) can also be optional; n) Proportionate admixture of the concentrate (36a) from step m) with CAM precursor (30), preferably in device (32) or upstream with feed (30) or directly in device (28);o) Concentrating the material stream (52) from step m) in unit (53), obtaining an alkali metal-poor (54) and alkali metal-rich (56) material stream, wherein; On concentration unit (53) can also be optional; p) Separation of acid residue anions in the stream (56) from o) or directly from (52) in unit (61) to form a (alkali) metal-rich material stream (60) and an anion-rich material stream or an acid (58), wherein the unit (61) can also be optional; q) collecting the acid (58) obtained from p) in container (59); r) dewatering the metal-rich material stream (60) from step p) in unit (63) and recycling the recovered alkali metal precursor (62) into the mixing device (21) back into the production process.

2. The method according to claim 1, wherein the solids separator (65) from step 1m) preferably consists of a solids filter (49) with collecting containers for filtrate (51) and concentrate (37) 28 AMENDED SHEET (ARTICLE 19) and / or a sedimentation unit (69) and / or a solid / liquid separation unit (73), wherein (49) is preferably a microfiltration or ultrafiltration unit. The resulting solids-free or low-solids solutions (50) and / or (68) and / or (72) are preferably collected in a collection container (51). The resulting solids-rich concentrate (36) is preferably collected in the container (37).

3. Method according to one of the preceding claims, wherein nanofiltration is preferably used as the concentration unit (53) in step 10).

4. Process according to one of the preceding claims, wherein the solids-rich concentrate (36) from the solids filter (49) in claim 2 is also further concentrated as a material stream (36b) in the subsequent steps of sedimentation (69) and / or solid / liquid separation (73) (thickener and / or chamber filter press and / or decanter), wherein the solids (74) are preferably mixed with solids (44) in the collecting container (33).

5. The method according to any one of the preceding claims, wherein the unit for solid / liquid separation (32) in step lh) is carried out by means of a chamber filter press, wherein the filtrate (42a) is preferably circulated at the beginning, the turbidity run being preferably monitored and controlled by sensors, the filtrate (42b) being fed to the receiver (47) during the clear run and the rinsing water (40) resulting from the filter cloth cleaning being fed into the washing water receiver (47).

6. Process according to one of the preceding claims, wherein the concentrations in step 1.1) can be adjusted as desired depending on the CAM product and process parameters, wherein the concentrations are selected such that the redissolution of alkali metal in the washing and rinsing process is as low as possible and precipitation of the components is excluded.

7. Method according to one of the preceding claims, wherein 29 AMENDED SHEET (ARTICLE 19) according to Figure 3, the respective material flows (40) and (42b) from solid / liquid separation (32), condensate (43) from collection tank (55) or directly from (9), (11) and (63), (46) from drying unit (45) and (54) from On the concentration unit (53) cascadingly fed to the wash water reservoir (47) and the material flow (48) is removed from cascade 47.

0.

8. Method according to one of the preceding claims, wherein the metal compound (7) comprises the metals selected from Ni, Mn, Co, Al, Zn, Fe, or mixtures thereof.

9. Method according to one of the preceding claims, wherein, depending on the precursors (5) and (7) used, the condensate mixture (43) can be supplemented or replaced with (deionized) water (8) as required, preferably in the container (55).

10. Process according to one of the preceding claims, wherein lithium oxide monohydrate (LiOH*1H2O) or other lithium compounds are preferably used as precursor (5).

11. A process according to claims 1 to 10, wherein the concentration of lithium in claim 6 is set in the range of 20 to 30 g / l.

12. The method according to claim 1p), wherein diffusion dialysis with a semipermeable or ion exchange membrane is used as the membrane separation method (61).

13. The method according to any one of the preceding claims, wherein the condensate mixture from the collecting tank (55) is used as feed (57) for the membrane separation process (61).

14. Process plant for carrying out the method according to one or more of claims 1 to 13.

15. Use of the process plant according to claim 14 for producing an alkali metal-containing cathode material and / or for obtaining acids (58), such as H2SO4, H3PO4, HNO3, H2CO3, etc. 30 AMENDED SHEET (ARTICLE 19) Declaration under Article 19(1) The amended patent claims should, if possible, also be included in the description. The facts and scope of the invention have not changed. The description has been adapted to reflect the new structure of the claims and is attached. DECLARATION REFERRED TO IN ARTICLE 19 (1)

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