Solid-solid separation of carbon from poorly soluble alkaline earth metal sulfates

Abstract

A process for recycling carbon and poorly soluble alkaline earth metal sulfates from a leach residue, the process comprising the steps of contacting a lithium battery material with a material comprising an alkaline earth metal in a solvent in an alkaline earth metal contacting step, producing an alkaline earth metal contacted lithium battery material; leaching the lithium battery material contacted with the alkaline earth metal in sulfuric acid in a leaching step, producing a leach solution and the leach residue, where the leach residue comprises carbon and the poorly soluble alkaline earth metal sulfate; separating the leach residue from the leach solution in a solid-liquid separation step; suspending the leach residue in a solvent in a suspending step, resulting in a suspended leach residue; contacting the suspended leach residue with a plurality of at least one type of carrier bodies in a carrier contacting step wherein at least a portion of the carbon contained in the suspended leach residue agglomerates with the plurality of at least one type of carrier bodies, generating a suspension comprising carbon-containing support body agglomerates and non-agglomerates comprising the poorly soluble alkaline earth metal sulfate, or wherein at least a portion of the poorly soluble alkaline earth metal sulfate contained in the suspended leach residue agglomerates with the plurality of at least one type of support body, producing a suspension comprising support bulk agglomerates comprising the poorly soluble alkaline earth metal sulfate and non-agglomerates comprising carbon; at least a portion of the support body agglomerates are separated from the suspension in a solid-solid separation step.

Description

[0001] The project leading to this application has received funding from the Federal Ministry for Economic Affairs and Climate Action (Bundesministerium für Wirtschaft und Klimaschutz) (Germany; FKZ: 16BZF101A); the applicants are responsible for all disclosures in this article. Technical Field

[0002] The present invention relates to a method for solid-solid separation of carbon and sparingly soluble alkaline earth metal sulfate, in particular for use in the recycling of lithium battery materials. Background Art

[0003] Storing electrical energy is a subject of increasing interest. Efficient storage of electrical energy will allow it to be generated when it is advantageous and used when and where it is needed. Secondary electrochemical cells are well suited for this purpose due to their rechargeability. Lithium batteries are therefore of particular interest for energy storage, since they offer a high energy density due to the small atomic weight and large ionization energy of lithium, and they have been widely used as a power source for many portable electronic devices such as cellular phones, laptop computers, miniature cameras, etc., and also as a power source for electric vehicles.

[0004] The life of batteries, especially lithium-ion batteries, is not infinite. Therefore, it is expected that more and more waste batteries will appear. Since waste batteries contain important metals, such as but not limited to cobalt, nickel, lithium, and additionally copper and aluminum, waste batteries may become a valuable source of raw materials for new generation batteries. For this reason, more and more research work has been carried out in order to recycle valuable metals and optionally even aluminum from used lithium-ion batteries.

[0005] Furthermore, recent developments on the world market have significantly increased the prices of important raw materials for battery production. Furthermore, on March 17, 2022, the EU Environment Ministers unanimously adopted the Security Council position on the EU battery regulation. It is foreseeable that this regulation will provide for certain recycling rates for batteries and also for certain recycling rates for metals used in batteries. Furthermore, such a regulation will most likely make it possible that at least a certain amount of the components used in the EU production of such batteries will also be components produced in the EU. Since there are no large mining operations in the EU for the required components, recycling will be the most advantageous way to produce such components within the EU. Therefore, there is a need for a sustainable, efficient and preferably well-integrated method for recycling components of batteries, in particular lithium batteries.

[0006] The cathode used in lithium batteries usually contains a large amount of aluminum as a carrier foil for the cathode active material. Some cathode active materials also contain aluminum, i.e. nickel cobalt aluminum oxide materials (NCA). Common materials contain nickel, cobalt and manganese (NCM). Other cathode active materials are known that do not contain nickel or cobalt, but instead contain lithium manganese oxide or lithium iron phosphate.

[0007] Lithium-ion batteries or parts of lithium-ion batteries that do not meet specifications and requirements (so-called substandard materials and production waste) can also be a source of raw materials.

[0008] Two main approaches have been carried out for raw material recovery. One main approach is based on smelting of the corresponding battery scrap and subsequent hydrometallurgical processing of the metal alloys obtained from the smelting process.

[0009] Another major method is direct hydrometallurgical processing of battery waste materials. The principle has been disclosed in WO 2017 / 091562 and J. Power Sources [Power Source Magazine], 2014, 262, 255 and below. Such hydrometallurgical methods will provide such transition metals as aqueous solutions or in precipitated form, for example, alone as hydroxides (DE-A-19842658), or already in the desired stoichiometry for making new cathode active materials, as proposed by Demidov et al., Ru. J. of Applied chemistry [Russian Journal of Applied Chemistry] 78, 356 (2005). In the latter case, the composition of the metal salt solution can be adjusted to the desired stoichiometry by adding a single metal component.

[0010] However, in addition to nickel, cobalt, manganese and aluminum, the recovery of lithium from battery waste has gained increasing interest. In WO 2021 / 018796A1, a method for recovering one or more transition metals and lithium from spent lithium-ion batteries is described. The method comprises the following steps: treating the battery waste with an alkaline earth metal hydroxide, preferably calcium hydroxide, thereby forming soluble lithium hydroxide, separating the solid from the liquid, and treating the solid containing the transition metal with an inorganic acid, preferably sulfuric acid, thereby producing a precipitate containing a large amount of carbon and a sparingly soluble alkaline earth metal sulfate, preferably gypsum, as a by-product.

[0011] These two components form a valuable resource source. The elemental carbon can be used again in the production of batteries. On the other hand, the sparingly soluble alkaline earth metal sulfates are also of interest. For example, gypsum is produced in large quantities, namely by flue gas desulfurization, for use in the construction industry, agriculture and medicine. Due to the future shift to more sustainable technologies, flue gases may become less available, so the need for new sources of gypsum may also become urgent. On the other hand, barite is used as a pigment and in the construction industry.

[0012] The problem of separating elemental carbon from sparingly soluble alkaline earth metal sulfates has not been solved in the literature so far. There are many reports on the use of gypsum to store carbon as carbon dioxide (e.g., Kang, C.-U. et al., Sustainability 2022, 14, 4436), but this is not the field of the present invention. Summary of the invention

[0013] Therefore, there is a need for a process which allows efficient separation of carbon and sparingly soluble alkaline earth metal sulfates from a solid mixture of these two materials.

[0014] It was therefore an object of the present invention to provide an efficient process for separating sparingly soluble alkaline earth metal sulfates and carbon, in particular a process which can be easily and reliably integrated into corresponding recycling processes for lithium battery materials.

[0015] It has now been unexpectedly found that the above objects can be achieved by a method comprising the following steps: in an alkaline earth metal contacting step, a lithium battery material is contacted with a material containing alkaline earth metal calcium in a solvent to produce an alkaline earth metal contacted lithium battery material; in a leaching step, the alkaline earth metal contacted lithium battery material is leached in sulfuric acid to produce a leaching solution and a leaching residue, wherein the leaching residue contains carbon and insoluble alkaline earth metal sulfate; in a solid-liquid separation step, the leaching residue is separated from the leaching solution; in a suspending step, the leaching residue is suspended in a solvent to produce a suspended leaching residue; in a carrier contacting step, the suspended leaching residue is leached in a carrier contacting step. The leaching residue is contacted with a plurality of at least one type of carrier bodies, wherein at least a portion of the carbon contained in the suspended leaching residue is agglomerated with the plurality of at least one type of carrier bodies to produce a suspension comprising carbon-containing carrier body agglomerates and non-agglomerates containing sparingly soluble alkaline earth metal sulfate, or wherein at least a portion of the sparingly soluble alkaline earth metal sulfate contained in the suspended leaching residue is agglomerated with the plurality of at least one type of carrier bodies to produce a suspension comprising carrier body agglomerates containing sparingly soluble alkaline earth metal sulfate and non-agglomerates containing carbon; and at least a portion of the carrier body agglomerates are separated from the suspension in a solid-solid separation step.

[0016] Therefore, both carrier agglomeration and subsequent separation processes are conceivable. However, in most practical cases, the hydrophobic material will agglomerate with the hydrophobic carrier body. However, the so-called reverse flotation method (wherein the hydrophilic component is separated in the concentrate) is known in the art. Such methods are usually achieved by the reversal of the surface tension characteristics of the target particles. In the following, the focus will be on the situation in which hydrophobic agglomerates are formed. However, this is by no means a general limitation, so the method in which the hydrophilic insoluble alkaline earth metal sulfate component is agglomerated is included in the present invention. Therefore, preferably, in the method of the present invention, the carrier contacting step is a step in which the suspended leaching residue is contacted with a plurality of at least one type of carrier body, wherein at least a portion of the carbon contained in the suspended leaching residue is agglomerated with a plurality of at least one type of carrier body, producing a suspension comprising carbonaceous carrier body agglomerates and non-agglomerates containing insoluble alkaline earth metal sulfate.

[0017] One advantageous effect of the present invention is that the method is carried out on the basis of solid-solid separation. Therefore, no dissolution step involving high energy input is required. Furthermore, the method can be used directly for the products emerging from the sulfuric acid leaching step. Therefore, a close and efficient integration with the lithium battery material recycling process is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD spectrum of the black substance used in Example 1 is shown (black graph).

[0019] definition

[0020] Before describing exemplary embodiments of the present invention in detail, definitions important for understanding the present invention are given.

[0021] The term "black mass" as used herein means the solid residue obtained by disassembling and pulverizing batteries. The black mass is obtained as a fine fraction of the classification stage and contains the active materials of the cathode and anode of the battery as well as some impurity particles. This black mass can be processed directly in a hydrometallurgical process or after a pyrolysis treatment.

[0022] As used in this specification and the appended claims, unless the context clearly stipulates otherwise, the singular form "a / an" also includes the corresponding plural. In the context of the present invention, the terms "about" and "approximately" represent that those skilled in the art will understand that the precision interval of the technical effect of the feature discussed is still guaranteed. The term typically indicates a deviation from the indicated numerical value of ±10%, preferably ±8%, more preferably ±5%, and even more preferably ±2%. It should be understood that the terms "comprising" and "including / encompassing" are not restrictive. For the purposes of the present invention, the term "consisting of..." is considered to be a preferred embodiment of the term "consisting of...". If a group is defined as including at least a certain number of embodiments below, this means that a group preferably consisting of only these embodiments is also covered. In addition, the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)" and the like in this specification and claims are used to distinguish similar elements and are not necessarily used to describe sequential or chronological order. It should be understood that the terms used in this way are interchangeable where appropriate, and the embodiments of the present invention described herein can operate in other sequences except as described or illustrated herein. In the case where the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", "i", "ii" etc. relate to a step of a method or purpose or a determination, there is no time or time interval coherence between these steps, i.e., these steps can be performed simultaneously or there can be a time interval of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in the present application as described above or below. It should be understood that the present invention is not limited to the particular methods, schemes, reagents, etc. described herein, because these can vary. It should also be understood that the terms used herein are only for the purpose of describing a particular embodiment, and are not intended to limit the scope of the present invention, which will be limited only by the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art.

[0023] As used herein, the term "does not comprise", "does not contain" or "does not contain" in this context means that the composition of the present invention does not contain a specific compound or group of compounds (which may be combined under collective terms), meaning that the composition does not contain said compound or group of compounds in an amount exceeding 0.8% by weight based on the total weight of the composition. Furthermore, it is preferred that the composition according to the present invention does not contain said compound or group of compounds in an amount exceeding 0.5% by weight, preferably the composition does not contain said compound or group of compounds at all.

[0024] When referring to weight percentages of compositions and ingredients contained therein, it is to be understood that the total amount of ingredients according to the present invention does not exceed 100% (± 1% due to rounding). DETAILED DESCRIPTION

[0025] The method of the present invention is a method for recycling carbon and sparingly soluble alkaline earth metal sulfate from leaching residues, the method comprising the following steps:

[0026] In the alkaline earth metal contact step, the lithium battery material is contacted with a material containing an alkaline earth metal in a solvent to produce an alkaline earth metal contacted lithium battery material;

[0027] In a leaching step, the alkaline earth metal-contacted lithium battery material is leached in sulfuric acid to produce a leaching solution and a leaching residue, wherein the leaching residue comprises carbon and a sparingly soluble alkaline earth metal sulfate;

[0028] separating the leaching residue from the leaching solution in a solid-liquid separation step;

[0029] suspending the leaching residue in a solvent in a suspending step to produce a suspended leaching residue;

[0030] contacting the suspended leaching residue with a plurality of at least one type of support bodies in a support contacting step,

[0031] wherein at least a portion of the carbon contained in the suspended leaching residue is agglomerated with a plurality of at least one type of support bodies to produce a suspension comprising support body agglomerates containing carbon and non-agglomerated sparingly soluble alkaline earth metal sulfate containing agglomerates of the sparingly soluble alkaline earth metal sulfate, or wherein at least a portion of the sparingly soluble alkaline earth metal sulfate contained in the suspended leaching residue is agglomerated with a plurality of at least one type of support bodies to produce a suspension comprising support body agglomerates containing agglomerates of the sparingly soluble alkaline earth metal sulfate and non-agglomerated sparingly soluble alkaline earth metal sulfate;

[0032] At least a portion of the carrier body agglomerates are separated from the suspension in a solid-solid separation step.

[0033] Typically, in the recycling method of batteries, especially lithium-ion-based batteries, a pyrolysis step is involved. This pyrolysis step is usually a thermal pretreatment step, in which the pre-sorted batteries or battery components are heated so that their constituent organic matter is decomposed. Therefore, preferably, the lithium battery material of the contacting step of the method of the present invention is a pyrolyzed lithium battery material. Preferably, the pyrolysis step is carried out under inert or reducing conditions. In the latter case, the reducing gas is preferably selected from hydrogen, carbon monoxide, nitrogen or hydrocarbons like methane (from natural gas). In the case of inert conditions, the presence of air or oxygen is excluded, and the atmosphere is mainly composed of inert gases like nitrogen, but carbon dioxide may also be present. When a directly heated oven is used, the hydrocarbon / oxygen or air mixture is incinerated, leaving an atmosphere mainly containing nitrogen and carbon dioxide.

[0034] The leaching residue used in the method of the present invention contains carbon. The carbon is mainly derived from the carbon present in the leached lithium battery material. The lithium battery material itself already contains carbon as an anode material. Since the lithium battery material is preferably a pyrolyzed lithium battery material, other carbon-based compounds may also have been at least partially formed into carbon during the pyrolysis process. This carbon can generally exist in any variant known for carbon except diamond. Therefore, preferably, in the method of the present invention, the carbon is amorphous carbon, preferably selected from a list consisting of carbon black and pyrolytic coke; or crystalline carbon, preferably selected from a list consisting of graphite, graphene, fullerene, buckyball, nanotube, and a mixture thereof. More preferably, the carbon in the method of the present invention is crystalline carbon, preferably selected from a list consisting of graphite, graphene, fullerene, buckyball, nanotube, and a mixture thereof, most preferably graphite.

[0035] The alkaline earth metal contacting step mainly provides a suspension of the lithium battery material in a polar solvent. Preferably, the polar solvent is a protic solvent, more preferably water.

[0036] The term "protic solvent" as used herein means water, alcohols, and mixtures thereof. An aqueous medium such as an aqueous solvent or an aqueous liquid contains primarily (i.e., 50 wt % or more, preferably 80 wt % or more, more preferably 90 wt % or more) water, including water and mixtures of water and one or more alcohols. It may contain additional dissolved substances as long as the primary water content remains within one or more of the ranges given above.

[0037] The term "alkaline earth metal" as indicated herein preferably refers to alkaline earth metals that form sparingly soluble sulfates, preferably calcium, strontium and barium, more preferably calcium and barium, most preferably calcium.

[0038] As used herein, the term "poorly soluble alkaline earth metal sulfate" means an alkaline earth metal sulfate that is hardly soluble in water, preferably calcium sulfate, strontium sulfate and barium sulfate, more preferably calcium sulfate and barium sulfate, most preferably calcium sulfate.

[0039] The term "calcium sulfate" as used herein refers to the pure compound calcium sulfate, but also to naturally occurring compounds such as gypsum, which consists mainly of calcium sulfate with small amounts of impurities and optionally water content.

[0040] The term "barium sulfate" as used herein refers to the pure compound barium sulfate, but also to naturally occurring compounds such as barite, which consists mainly of barium sulfate with small amounts of impurities and optionally water content.

[0041] Preferably, the alkaline earth metal contacting step is carried out under heating. Preferably, it is carried out at a temperature in the range of 60°C to 200°C, preferably 70°C to 150°C. When the boiling point of the polar solvent is exceeded, the alkaline earth metal contacting step is carried out under pressure to keep the solvent or at least a portion thereof in a liquid state. Of particular technical importance is the temperature range around the boiling point of water, i.e., about 70°C to 150°C, wherein the treatment can be achieved using an aqueous liquid or water at normal pressure or slightly elevated pressure (e.g., up to 5 bar). Alternatively, the alkaline earth metal contacting step can be carried out at higher temperatures and pressures, such as 150°C to 300°C and 1.5 to 100 bar. Most preferably, the alkaline earth metal contacting step is carried out at a temperature in the range of 95°C to 100°C at normal pressure.

[0042] The alkaline earth metal contacting step is performed by combining a certain amount of alkaline earth metal-containing material (ACM) with a lithium battery material (LBM), the alkaline earth metal-containing material is preferably selected from a list consisting of calcium oxide, calcium hydroxide, calcium hypochlorite, strontium hydroxide or strontium oxide and barium hydroxide or barium oxide or a mixture thereof, and the ACM preferably corresponds to at least 5wt% and not more than 250wt% of the weight of the LBM, for example, 50-2500g ACM relative to 1kg LBM, more preferably 100-1000g ACM relative to 1kg LBM, and most preferably 200-1000g relative to 1kg LBM. It should be understood that in certain embodiments of the present invention, ACM can be added to LBM before pyrolysis. In such an embodiment, in the alkaline earth metal contacting step, only a solvent can be added to achieve contact. It is also possible to mix this embodiment with an embodiment in which ACM is added together with a solvent. Therefore, it is possible that ACM has been added to LBM before pyrolysis, but in the contacting step, not only a solvent but also additional ACM is added.

[0043] Preferably, the alkaline earth metal contained in the alkaline earth metal-containing material used in the alkaline earth metal contacting step is calcium or barium, most preferably calcium. If the alkaline earth metal contained in the alkaline earth metal-containing material is barium, the alkaline earth metal-containing material is preferably barium hydroxide or barium oxide. If the alkaline earth metal contained in the alkaline earth metal-containing material is calcium, the alkaline earth metal-containing material is preferably selected from calcium hydroxide, calcium oxide, or calcium hypochlorite, preferably calcium hydroxide.

[0044] The amount of polar solvent in the alkaline earth metal contacting step is typically selected to ensure miscibility of the components, for example, 0.5 to 95, preferably about 2.5 to 21 parts by weight of polar solvent is used per one part by weight of the combined solids (LBM and ACM); or in some cases 1 to 20, for example about 2 to 10 parts by weight of polar solvent is used.

[0045] Preferably, in the alkaline earth metal contacting step of the method of the present invention, a molar ratio between the alkaline earth metal contained in the alkaline earth metal-containing material and the lithium contained in the lithium battery material is in the range of 10:1 to 1:10.

[0046] In a preferred embodiment of the invention, the alkaline earth metal contacting step is carried out in a container protected from strong bases, such as molybdenum and copper rich steel alloys, nickel-based alloys, duplex stainless steels, or glass lined or enameled or titanium coated steels. Further examples are polymer liners and polymer containers from alkali resistant polymers, such as polyethylenes such as HDPE and UHMPE, fluorinated polyethylenes, perfluoroalkoxyalkanes ("PFA"), polytetrafluoroethylene ("PTFE"), PVdF and FEP. FEP stands for fluorinated ethylene propylene polymer, i.e. a copolymer from tetrafluoroethylene and hexafluoropropylene.

[0047] The alkaline earth metal contact step is preferably carried out using a mixing device (e.g., a stirrer), wherein the power applied is preferably up to 10 W / kg suspension, more preferably 0.5 to 10 W / kg, and / or circulated by pumping to achieve good mixing and avoid sedimentation of insoluble components. Shearing can preferably be further improved by using a baffle. In addition, the slurry obtained in the alkaline earth metal contact step can preferably be subjected to a grinding process, such as in a ball mill or a stirred ball mill. Such a grinding process can result in a polar solvent being better accessible to the lithium battery material. The shearing and grinding devices used are preferably sufficiently corrosion-resistant. Preferably, they are produced by similar materials and coatings as described above for the container.

[0048] Preferably, the alkaline earth metal contacting step has a duration ranging from 20 min to 24 h, more preferably from 2 h to 10 h, even more preferably from 4 h to 8 h, and most preferably from 5 h to 7 h.

[0049] In a particularly preferred embodiment of the present invention, the alkaline earth metal contacting step is performed at least twice to achieve optimal recovery of the lithium salt. Between each treatment, a solid-liquid separation is preferably performed. The obtained lithium salt solutions can be combined or treated separately to recover solid lithium salts. The specific lithium salt formed during the alkaline earth metal contacting step depends on the alkaline earth metal-containing material used. Calcium oxide, calcium hydroxide, and barium hydroxide and barium oxide lead to the formation of lithium hydroxide, while calcium hypochlorite leads to the formation of lithium chloride.

[0050] The alkaline earth metal contacted lithium battery material obtained in the alkaline earth metal contact step is preferably recovered by solid-liquid separation. It can be filtration, centrifugation, a sedimentation, decantation, or a combination thereof, preferably followed by a washing step in which the corresponding polar solvent used in the alkaline earth metal contact step is applied as a washing medium. The filtrate and the washing liquid are preferably combined before further treatment for lithium salts. In order to recover such solid material containing fine particles (e.g., an average diameter of 50 pm or less), a flocculant, such as a polyacrylate, can be added.

[0051] The obtained alkaline earth metal contacted lithium battery material is preferably characterized by an alkaline earth metal element weight content of between 2 and 70 wt% relative to the total dry mass of the alkaline earth metal contacted lithium battery material.

[0052] The alkaline earth metal contacted lithium battery material obtained in the alkaline earth metal contacting step is then subjected to a leaching step. However, preferably, prior to the leaching step, a subsequent solid-solid separation step for removing Ni and / or Co (if present) may be performed. By performing this step, nickel may be recovered as a nickel-containing solid.

[0053] Likewise, preferably, the alkaline earth metal contacting step and the subsequent solid-solid separation step are carried out in a batch mode. In another preferred embodiment of the present invention, the alkaline earth metal contacting step and the subsequent solid-solid separation step are carried out in a continuous mode, for example, in a cascade of stirred vessels (alkaline earth metal contacting step) and / or in a cascade of stirred vessels plus centrifuges (subsequent solid-solid separation step).

[0054] In the leaching step, sulfuric acid, preferably an aqueous sulfuric acid solution, is used for leaching. The concentration of the aqueous sulfuric acid solution is preferably in the range of 10 to 98 wt%, most preferably 10 to 80 wt%. Therefore, the sulfuric acid in the leaching step is preferably present in a concentration of at least 0.05 wt%, more preferably at least 0.5 wt%, and most preferably at least 5 wt%. Preferably, the aqueous sulfuric acid solution has a pH value in the range of -1 to 2. The amount of acid is preferably adjusted to maintain an excess of acid relative to the transition metals still present in the lithium battery material in contact with the alkaline earth metal. Preferably, at the end of the leaching step, the pH value of the resulting solution is in the range of -0.5 to 2.5.

[0055] The leaching step may be carried out in the presence of an oxidant. Preferably, the oxidant is selected from the list consisting of oxygen, air, hydrogen peroxide, nitrous oxide, metal oxide compounds like lithium metal oxides, permanganates, ferrates, or mixtures thereof. The preferred oxidant is oxygen as a pure gas or in a mixture with an inert gas such as nitrogen or air.

[0056] The leaching step is preferably carried out at a temperature in the range of 20° C. to 200° C., more preferably 20° C. to 130° C., even more preferably 50° C. to 110° C., still even more preferably 70° C. to 105° C., and most preferably 85° C. to 100° C. If a temperature above 100° C. is desired, the leaching step is carried out at a pressure above 1 bar. Otherwise, normal pressure is preferred.

[0057] In a preferred embodiment of the invention, the leaching step is carried out in a container protected from strong acids, such as molybdenum and copper rich steel alloys, nickel-based alloys, duplex stainless steels or glass lined or enameled or titanium coated steels. Further examples are polymer liners and polymer containers from acid resistant polymers, such as polyethylenes such as HDPE and UHMPE, fluorinated polyethylenes, perfluoroalkoxyalkanes ("PFA"), polytetrafluoroethylene ("PTFE"), PVDF and FEP.

[0058] The slurry obtained in the leaching step may be stirred, agitated, or subjected to a grinding treatment, for example in a ball mill or a stirred ball mill. Such grinding treatments often result in better access of water or acid to the particulate transition metal material.

[0059] In a preferred embodiment of the invention, the leaching step has a duration in the range of 10 min to 10 h, preferably 1 h to 9 h, more preferably 3 h to 7 h, and most preferably 4 h to 6 h. For example, the reaction mixture in the leaching step is stirred or circulated by pumping at a power of at least 0.1 W / l to achieve good mixing and avoid sedimentation of insoluble components. Shearing can be further improved by using baffles. All these shearing devices need to be applied with sufficient corrosion resistance and can be produced by similar materials and coatings as described for the container itself.

[0060] The leaching step can be carried out under an air atmosphere or under air diluted with N2. It is preferred to carry out the leaching step under an inert atmosphere (e.g. nitrogen or a noble gas such as Ar).

[0061] The treatment according to the leaching step results in the dissolution of the metal compounds (including impurities other than carbon and organic polymers) remaining after the alkaline earth metal contacting step. In most embodiments, a slurry is obtained after performing the leaching step. Residual lithium and transition metals, such as but not limited to nickel, cobalt, copper and (if applicable) manganese, are often in dissolved form during leaching, for example in the form of their salts.

[0062] In embodiments where a so-called oxidizing acid or oxidizing agent has been used in the leaching step, it is preferred to add a reducing agent to remove the unused oxidizing agent. Examples of oxidizing acids are nitric acid and a combination of nitric acid and hydrochloric acid, and examples of oxidizing agents are lithium metal oxides, hydrogen peroxide or oxygen.

[0063] After the leaching step, the solid-liquid separation step is preferably carried out as a separation step according to one or more of the list consisting of a filtration step, a centrifugation step, a sedimentation step and a decantation step, preferably as a filtration step. The solid residue obtained may be washed with a polar solvent.

[0064] Preferably, the leaching step and the solid-liquid separation step are performed sequentially in a continuous operation.

[0065] Since the leaching step preferably employs a polar solvent, preferably a protic solvent, more preferably water, the solvent used in the suspending step of the method according to the invention is also preferably a polar solvent, more preferably a protic solvent, most preferably water.

[0066] In a preferred embodiment of the invention, the suspension step is carried out in a container protected from strong acids, such as molybdenum and copper rich steel alloys, nickel-based alloys, duplex stainless steels or glass lined or enameled or titanium coated steels. Further examples are polymer liners and polymer containers from acid resistant polymers, such as polyethylenes such as HDPE and UHMPE, fluorinated polyethylenes, perfluoroalkoxyalkanes ("PFA"), polytetrafluoroethylene ("PTFE"), PVDF and FEP.

[0067] The suspension obtained in the suspending step may be stirred, agitated, or subjected to a grinding process, for example in a ball mill or a stirred ball mill. Such grinding processes often result in finer suspensions. The carbon particles in the suspension typically have an average diameter that enables such particles to effectively agglomerate with the support body in a subsequent support contacting step. In a preferred embodiment, the carbon particles have a D50 in the range of 1 nm to 1 mm, and preferably 0.1 μm to 500 μm and most preferably between 1 μm and 250 μm. The particle size of the carbon particles can be reduced by grinding or milling.

[0068] In a subsequent support contacting step of the process of the present invention, the suspended leaching residue is contacted with a plurality of at least one type of support bodies, wherein preferably at least a portion of the carbon contained in the suspended leaching residue is agglomerated with the plurality of at least one type of support bodies, preferably producing a suspension comprising carbon-support body agglomerates and sparingly soluble alkaline earth metal sulfate.

[0069] The term "carrier body" as used herein means a compound or physical entity, which can be bound to one or more particles to be separated, preferably carbon particles in a suspension by physical interaction or chemical interaction. Therefore, those interactions can be from covalent bonding via dipole-dipole bonds to Van der Waals interactions. Physical interactions can be specifically encapsulating particles to be separated, preferably carbon particles, in cavities, whereby these cavities can be formed by chemical structures or physical means such as phase boundaries. It is preferred that the carrier body specifically interacts with particles to be separated, preferably carbon particles, and does not interact with particles not to be separated, preferably insoluble alkaline earth metal sulfate particles. Carbon is generally a non-polar compound, and insoluble alkaline earth metal sulfates preferably interact with polar compounds and entities as salts. Therefore, the characteristics of the carrier body must be selected accordingly. Therefore, preferably, the additional requirement for the carrier body is that they form agglomerates with each other or with the carbon residues combined, preferably form agglomerates with each other. Such agglomeration ensures the easier separation of the carbon-carrier body. Finally, the carbon-support entity interaction must be separable following solid-solid separation of the carbon-support entity and the sparingly soluble alkaline earth metal sulfate.

[0070] In the carrier contact step, preferably, a collector is added to the suspension. Suitable collectors selectively form a hydrophobic layer on the carbon particles. Suitable collectors are preferably liquid non-polar compounds that do not dissociate in water. Preferably, the collector is a hydrocarbon. The hydrocarbon can be a uniform hydrocarbon or a hydrocarbon mixture. The hydrocarbon can have a viscosity of 0.1 to 100 cP, preferably 0.5 to 5 cP, in each case at 20 ° C. The hydrocarbon can be a mineral oil, a vegetable oil, a biodiesel, a BtL (biomass-to-liquid) fuel, a product of coal liquefaction, a product of a GtL (gas to liquid, from natural gas) process, a long-chain alcohol, and a mixture thereof. The collector is preferably a mineral oil. Suitable mineral oils are crude oil derivatives and / or oils produced by distillation of lignite, hard coal, peat, wood, petroleum and (if appropriate) other mineral raw materials. Mineral oils generally include hydrocarbon mixtures of paraffinic hydrocarbons (i.e., saturated straight-chain and branched hydrocarbons), cycloalkanes (i.e., saturated cyclic hydrocarbons), and aromatic hydrocarbons. Preferably, the collector is selected from non-polar hydrocarbons, preferably non-polar aliphatic hydrocarbons, and most preferably C9 to C 17 Aliphatic non-polar hydrocarbons.

[0071] The collector is typically added to the suspension in an amount of up to 15 wt%, preferably up to 7 wt%, and in particular up to 4 wt%, relative to the total dry mass of the suspension. More specifically, the suspension typically comprises 0.001 to 10 wt%, preferably 0.1 to 5 wt%, and in particular 0.2 to 3 wt% of collector relative to the total dry mass of the suspension. In another preferred embodiment form, the suspension typically comprises at least 0.05 wt%, preferably at least 0.1 wt%, and in particular at least 0.3 wt% of collector relative to the total dry mass of the suspension.

[0072] Therefore, after the support contacting step, a solid-solid separation step is performed, in which the support body agglomerates are separated from the sparingly soluble alkaline earth metal sulfate suspension. Therefore, the support contacting step and the solid-solid separation step are linked to each other, because the support body agglomerates must be suitable for separation by the solid-solid separation step.

[0073] Preferably, the solvent in the support contacting step is a polar solvent, more preferably a protic solvent, most preferably water.

[0074] Typically, after the leaching step, the leaching residue has a low pH. Therefore, preferably, in the support contacting step, before adding a plurality of at least one type of support bodies, the pH of the solvent is adjusted to a pH value above 3, preferably in the range of 3 to 8. Preferably, in the support contacting step, before adding a plurality of at least one type of support bodies, the pH is adjusted by adding a base selected from the list consisting of alkali metal hydroxides, alkali metal carbonates, ammonium hydroxide, alkaline earth metal hydroxides, alkaline earth metal carbonates or mixtures thereof, preferably at least one alkali metal hydroxide, preferably sodium hydroxide.

[0075] Preferably, the type of carrier bodies is selected from bubbles of a carrier gas and magnetic particles.

[0076] Suitable magnetic particles can be selected from magnetic metals, preferably iron and its alloys, cobalt, nickel and mixtures thereof, ferromagnetic or ferrimagnetic alloys of magnetic metals, such as NdFeB, SmCo and mixtures thereof, magnetic iron oxides, such as magnetite, magnetic hematite, hexagonal ferrite, cubic ferrite and mixtures thereof. Preferably, the magnetic particles are magnetic iron oxides, in particular magnetite.

[0077] The magnetic particles typically have an average diameter that enables such particles to effectively agglomerate with the desired particles.In preferred embodiments, the magnetic particles have a D50 in the range of 1 nm to 1 mm, and preferably 0.1 μm to 50 μm and most preferably in the range of 1 μm to 20 μm.

[0078] The expression "D50" means that 50% by weight of the respective particles have a diameter smaller than the stated value.The particle size of magnetic particles, such as magnetite, may be reduced by grinding or milling before use.

[0079] Typically, the amount of magnetic particles to be applied in the process of the invention can be determined in such a way that advantageously the entire amount of particles to be separated, preferably carbon particles, can be separated by agglomeration with the magnetic particles. In a preferred embodiment, the magnetic particles are added in an amount of 0.01% to 100% by weight, preferably 0.1% to 20% by weight, particularly preferably 0.5% to 10% by weight and most preferably 1% to 5% by weight, relative to the total dry mass of the dry leaching residue.

[0080] The magnetic particles are hydrophobic magnetic particles. Typically, the magnetic particles are hydrophobized on their surface, i.e., are hydrophobized magnetic particles. Preferably, the magnetic particles have been hydrophobized by treatment with a hydrophobizing agent, wherein preferably, the contact angle between the particle surface of the magnetic particles treated with the hydrophobizing agent and water relative to air is preferably greater than 30°, more preferably greater than 60°, even more preferably greater than 90° and particularly preferably greater than 140°. Preferably, the magnetic particles have been pretreated with a hydrophobizing agent before the carrier contact step.

[0081] In general, the hydrophobizing agent can be any agent that makes the surface of the magnetic particles more hydrophobic than the surface of the magnetic particles before treatment. Suitable hydrophobizing agents and methods for preparing hydrophobic magnetic particles by treatment with hydrophobizing agents are known, such as those listed in WO 2016 / 083491, page 19, line 21 to page 27, line 30, or in WO 2015 / 110555, page 7, line 9 to page 11, line 32.

[0082] Examples of hydrophobic agents are

[0083] Polyorganosiloxane;

[0084] Alkyl silicates, such as alkali metal or alkaline earth metal C 1-6 Alkyl silicates, especially methyl silicates;

[0085] Alkyltrichlorosilane, such as C 6-12 Alkyltrichlorosilane;

[0086] Alkyltrimethoxysilane, such as C 6-12 Alkyltrimethoxysilane;

[0087] Alkylphosphonic acid, such as C 6-18 Alkylphosphonic acids, especially octylphosphonic acid;

[0088] Mono- or dialkyl phosphates, such as C 6-18 Mono- or dialkylphosphoric acids;

[0089] Fatty acids, such as C 6-18 Fatty acids, in particular lauric acid, oleic acid, stearic acid; maleic acid olefin copolymers or mixtures thereof.

[0090] The hydrophobic agent is preferably a polyorganosiloxane. Polyorganosiloxane (also known as silicone) generally has the formula [R m Si(O) 4-m / 2 ] n , wherein m is 1 to 3, n is at least 2, and R is an organic residue, such as methyl, ethyl or phenyl. The polyorganosiloxane may be linear, cyclic or branched. Suitable polyorganosiloxanes and their preparation are known from Ullmann's Encyclopedia of Industrial Chemistry, Volume 32, entry "Silicones", Wiley-VCH, 2012, pages 675-712.

[0091] Suitable polyorganosiloxanes are silicone oils, silicone rubbers, silicone resins, or block and graft polyorganosiloxane copolymers, with silicone oils and silicone resins being more preferred.

[0092] Silicone oil (also called silicone fluid) is generally a linear polyorganosiloxane typically having 2 to 4000 monomer units. Suitable silicone oils are methyl silicone oil, methylphenyl silicone oil, fluorosilicone oil, methylhydrogen silicone oil, or methylalkyl silicone oil. Preferred silicone oils are methyl silicone oil and methylphenyl silicone oil.

[0093] Suitable methyl silicone oils are linear polydimethylsiloxanes, which may have a molecular mass of 500 to 200,000 g / mol. Suitable methylphenyl silicone oils are linear polydimethylsiloxanes in which the methyl groups are partially substituted by phenyl groups, and which may have a molecular mass of 500 to 200,000 g / mol.

[0094] Silicone resins are typically branched polyorganosiloxanes having a molecular weight of less than 15,000 g / mol, preferably less than 10,000 g / mol. Silicone resins are generally soluble in organic solvents such as toluene. Preferred silicone resins are MQ, TD and T-type silicone resins. Typically, silicone resins are prepared by hydrolysis or alcoholysis of organochlorosilanes such as methyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, and diphenyldichlorosilane.

[0095] Preferably, the hydrophobic agent is a silicone resin, such as a silicone resin having a molecular weight of less than 10,000 g / mol and having the formula [R m Si(O) 4-m / 2 ] n A branched polyorganosiloxane wherein m is from 1.1 to 3, n is at least 10, and R is an organic residue such as methyl or phenyl.

[0096] Suitable block and grafted polyorganosiloxane copolymers are polyorganosiloxane-polyether block polymers, wherein the polyether blocks may contain polyethylene glycol and / or polypropylene glycol; or graft polymers of polyorganosiloxane with vinyl monomers such as styrene, acrylates, or vinyl acetate.

[0097] Preferably, the magnetic particles comprise hydrophobized magnetite, preferably magnetite hydrophobized using a polyorganosiloxane as explained above.

[0098] Both gas bubbles and magnetic particles form aggregates with carbon in particular. This is due to the hydrophobic character of both entities. Gas bubbles have a polar solvent-gas phase boundary and an internal non-polar gas phase. Therefore, carbon particles tend to aggregate at the surface of the phase boundary or in the phase boundary using preferred non-polar interactions. On the other hand, hydrophobized magnetic particles aggregate with hydrophobic carbon particles, thereby forming hydrophobic aggregates, with the aim of minimizing their surface towards the polar solvent.

[0099] Preferably, the carrier gas is a gas inert to the suspension, preferably selected from the list consisting of air, oxygen-reduced air, nitrogen and carbon dioxide.

[0100] In general, the solid-solid separation step can be performed by a process step selected from the group consisting of sorting, electrical separation, magnetic separation, screening, classification, gravity concentration, flotation, or a mixture thereof.

[0101] If the type of carrier bodies is gas bubbles, the solid-solid separation step is preferably a flotation step.

[0102] The term "flotation" as used therein means a method step in which a carrier gas is injected into a flotation cell to cause the formation of hydrophobic bubbles, which can transport the hydrophobic or hydrophobized particles to the top of the flotation cell. The formed foam (which can be further stabilized by a suitable chemical acting as a frother) contains concentrated hydrophobic or hydrophobized particles (usually expressed as concentrate). Finally, the foam is removed from the top and the non-hydrophobic particles are left at the bottom of the flotation cell, usually expressed as tailings. Preferably, the flotation step is carried out in a mechanical flotation cell, in a pneumatic flotation cell, in a column flotation cell, or in a method comprising a plurality of flotation cells that may be the same or different types.

[0103] Typically, the foaming agent is a surfactant, preferably an organic isopolar compound, more preferably an alcohol or a polyethylene glycol ether, and most preferably methyl isobutyl carbinol (MIBC).

[0104] It should be understood that the solid-solid separation step can be performed in several steps. Thus, the same type of solid-solid separation step can be repeated more than once or different types of separation steps can be combined. For example, in the case of flotation, it is preferred that the solid-solid separation step includes more than one flotation step, preferably including a roughing step, a scavenging step, a concentrating step, or a combination thereof. Thus, the roughing step can be considered as the first flotation step. The scavenging step is a second flotation step using the tailings of the first flotation step (roughing step). Therefore, the scavenging step is usually performed to increase the separation yield of the carbon particles. Therefore, the foam of the roughing step and the scavenging step is preferably combined. The concentrating step is preferably performed using the foam of the roughing step or the combined foam of the roughing step and the scavenging step. This foam is resuspended in a fresh polar solvent and subjected to a flotation step. The concentrating step is preferably performed to increase the purity of the carbon particles.

[0105] After the flotation step or combination of flotation steps, both the tailings and the froth(s) are preferably subjected to a solid-liquid separation step, the separated solids are preferably washed with a suitable solvent, preferably a polar solvent, and dried for further use.

[0106] Therefore, in a preferred embodiment of the carrier body contacting step and the solid-solid separation step of the present invention, the carrier body is a bubble from a carrier gas, wherein the carrier gas is preferably an inert gas, most preferably air, and the solid-solid separation step comprises at least one flotation step, preferably a roughing step, a scavenging step, a beneficiation step, or a combination thereof, most preferably a roughing step, a scavenging step and a beneficiation step.

[0107] If the type of carrier body is magnetic particles, the solid-solid separation step is preferably selected from flotation, magnetic separation or a combination thereof, preferably magnetic separation. Magnetic separation is usually achieved by separation using a magnetic field. Separation by a magnetic field can be carried out by any method known to those skilled in the art. Suitable magnetic separators are drum separators, high-intensity or low-intensity magnetic separators, continuous belt separators or other. Permanent magnets or electromagnets can be used to generate a magnetic field. Magnetic separation can be carried out by continuous or semi-continuous magnetic separation techniques, as described by, for example, Jan Svoboda "Magnetic Techniques for the Treatment of Materials" (2004).

[0108] Suitable magnetic separator is LIMS (low intensity magnetic separator), MIMS (medium intensity magnetic separator) or WHIMS (wet high intensity magnetic separator) type as known in the art. In a preferred embodiment of the present invention, separator is MIMS or WHIMS type. Typical devices for magnetic separation are disclosed in WO 2011 / 131411, WO 2011 / 134710, WO 2011 / 154178, DE 102010 023 130, DE 20 2011 104 707, WO 2011 / 107353, DE 10 2010 061 952, WO 2012 / 116909, WO 2012 / 107274, WO 2012 / 104292 or WO 2013 / 167634. The magnetic separator preferably further comprises at least one magnet which is movable along a channel through which the slurry containing the magnetizable particles flows. The magnetic separator preferably operates in counter-flow, i.e. the movement of the magnetic field is opposite to the direction of the suspension flow. The field strength of the magnetic field may be at least 0.1, preferably at least 0.3 and in particular at least 0.5 Tesla.

[0109] In a preferred embodiment, the magnetic separation device allows washing the agglomerates with a dispersant, preferably water, during separation. Washing preferably allows removing inert material, ie material that has not been hydrophobized, from the agglomerates.

[0110] This magnetic separation step can be repeated, in particular by repeatedly flowing the non-magnetic products of the preceding separation step through a continuous separation path or by modulating the magnetic field. In this continuous separation step (referred to in the art as sweeping), additional amounts of collectors and / or hydrophobic magnetic particles can be added before the magnetic separation stage, as described above for step b). The agglomerates can be stirred after the first separation and before the second separation, so that the captured second type of particles can solidify freely and can be separated in the second separation step (referred to in the art as concentrating).

[0111] After the magnetic separation step, the carbon-support bulk agglomerates need to be broken up to obtain a suspension comprising the magnetic particles in deagglomerated form.

[0112] The decomposition of the separated agglomerates and the separation of the carbon particles from the magnetic particles are usually carried out in order to recycle the magnetic particles. The decomposition can be achieved by adding a cracking agent. The cracking agent can include an organic solvent, an alkaline compound, an acidic compound, an oxidizing agent, a reducing agent, a surfactant or a mixture thereof. Preferably, the cracking agent includes a mixture of water and a surfactant, and most preferably, the cracking agent is a surfactant.

[0113] Examples of organic solvents as cracking agents are alcohols, such as methanol, ethanol, propanols, such as n-propanol or isopropanol; aromatic solvents, such as benzene, toluene, xylene; ethers, such as diethyl ether, methyl tert-butyl ether; ketones, such as acetone; aromatic or aliphatic hydrocarbons, such as saturated hydrocarbons having, for example, 6 to 10 carbon atoms, such as dodecane, diesel fuel and mixtures thereof. The main components of diesel fuel are mainly alkanes, cycloalkanes and aromatic hydrocarbons having about 9 to 22 carbon atoms per molecule and a boiling range between 170° C. and 390° C.

[0114] The acidic compound may be an inorganic acid, such as HCl, H2SO4, HNO3 or a mixture thereof, or an organic acid, such as a carboxylic acid.

[0115] As oxidizing agent, H2O2 can be used, for example as a 30% strength by weight aqueous solution.

[0116] Examples of basic compounds are aqueous solutions of basic compounds, for example aqueous solutions of alkali metal and / or alkaline earth metal hydroxides, such as KOH or NaOH; lime water, aqueous ammonia solution, aqueous solutions of organic amines.

[0117] Examples of surfactants are nonionic, anionic, cationic and / or zwitterionic surfactants. In a preferred embodiment, the lysis is carried out by using a preferably biodegradable and / or nonionic surfactant in a concentration in the range of or above the critical micelle concentration. Preferably, the lysis agent is a nonionic surfactant added in an amount of 0.001% to 10%, preferably 0.01% to 1% by weight, based on the weight of the total solid phase employed in step d). The surfactant concentration is preferably at least greater than its critical micelle concentration (CMC), more preferably at least twice as high as its CMC.

[0118] Disintegration may also be assisted mechanically, such as by ultrasound or stirring or pumping in circulation or by grinding.

[0119] It will be appreciated that the magnetic separation step may be performed several times, such that the purity of the separated carrier body agglomerates is increased.

[0120] Measurement method

[0121] a) Particle size distribution

[0122] Particle size distribution measurements (including determination of D50) were performed according to ISO 13320 EN:2009-10.

[0123] b) Elemental analysis

[0124] Lithium, calcium, manganese, nickel, cobalt, copper, aluminum, iron and phosphorus (ICP-OES)

[0125] Reagents used:

[0126] Deionized water, hydrochloric acid (36%), K2CO3-Na2CO3 mixture (dry), Na2B4O7 (dry), hydrochloric acid 50 vol.-% (1:1 mixture of deionized water and hydrochloric acid (36%)); all reagents are of pa grade.

[0127] Sample preparation: 0.2-0.25 g of the material to be analyzed was weighed into a Pt crucible and K2CO3-Na2CO3 / Na2B4O7 melt digestion was applied: the sample was burned in an unshielded flame and then completely ashed in a muffle furnace at 600°C. The remaining ash was mixed with K2CO3-Na2CO3 / Na2B4O7 (0.8 g / 0.2 g) and melted until a clear melt was obtained. The cooled molten cake was dissolved in 30 mL of water and 12 mL of 50 vol.-% hydrochloric acid was added. The solution was brought to a specified volume of 100 mL. This post-treatment was repeated three times independently; in addition, a blank sample was prepared for reference purposes.

[0128] Measurement: Li, Mg, Ca, Ni, Co, Mn, Cu, Al, Fe, P in the obtained solution were determined by optical emission spectroscopy (ICP-OES) using inductively coupled plasma. Instrument: ICP-OES Agilent 5100SVDV; Wavelength: Li 670.783 nm; Ca 396.847 nm; Ni 231.604 nm; Co 238.892 nm; Mn 257.610 nm; Cu 324.754 nm; Al 396.152 nm; Fe 328.204 nm; P 213.617 nm; Internal standard: Sc 361.383 nm; Calibration: External.

[0129] Fluorine and fluoride (ISE)

[0130] The sample preparation for the elemental analysis of fluorine and fluoride was carried out according to DIN EN 14582:2016-12. The detection method was the ion-selective electrode measurement method according to DIN 38405-D4-2:1985-07 (water samples; digestion of inorganic solids, subsequent distillation with acid loading and fluoride determination using an ion-selective electrode).

[0131] carbon

[0132] In all cases, the total carbon concentration was determined by measuring carbon dioxide after combustion using a thermal conductivity detector as described in DIN 51732:2014-07.

[0133] sulfur

[0134] If not stated otherwise in the examples, sulfur was determined by catalytic combustion of the sample in an argon / oxygen atmosphere, whereby all sulfur was converted into a SO2 / SO3 gas mixture. After catalytic reduction of SO3 to SO2, SO2 was analyzed by IR spectroscopy.

[0135] c) Powder X-ray Diffraction (PXRD)

[0136] The phase composition of the solid, including the identification of manganese (II) oxide and Ni and Co in oxidation states below +2 (typically metallic), was determined by powder x-ray diffraction (PXRD).

[0137] Sample preparation: The samples were ground into fine powder and filled in the sample holder.

[0138] Measurements: Two devices were used, each using its specific radiation source: (1) Measurements with applied Cu radiation: the instrument used was a Bruker D8 Advance Series 2 with an automatic sampling unit; primary side: Cu-anode, beam divergence angle aperture 0.1°, with ASS; secondary side: scattered beam aperture 8 mm, with Ni 0.5 mm, Soller 4°, Lynx-Eye (3° aperture); (2) Measurements with applied Mo radiation: the instrument used was a Bruker D8 DiscoverA25 with an automatic sampling unit; primary side: Mo-anode, with Johansson monochromator (Mo-K-alpha1) and axial Soller 2.5°, secondary side: ASS, Soller 2.5°, Lynx-Eye XE detector (3.77° aperture).

[0139] References were used to identify matches with the obtained reflection patterns. All relevant phases are well known in the literature; the following references were consulted and used to calculate theoretical diffraction patterns (see positions and intensities of reflections in Table 1 below):

[0140] a)Co x Ni 1-x ; Space group Fm-3m;

[0141] x=0.5: Taylor et al., J. Inst. Met. (1950) 77, 585-594.

[0142] x=0: Buschow et al.; J. Magn. Magn. Mater. [Journal of Magnetism and Magnetic Materials] 1983, 38, 1-22.

[0143] b) Co; space group P63 / mmc; Buschow et al.; J. Magn. Magn. Mater. [Journal of Magnetism and Magnetic Materials] 1983, 38, 1-22.

[0144] c) Li2CO3, space group C2 / c; J. Alloys Compd. (2011), 509, 7915-7921

[0145] d) LiAlO2, space group R-3m; Marezio et al., J. Chem. Phys. (1966) 44, 3143-3145.

[0146] e) MnO, space group Fm-3m, Locmelis et al., Z. Anorg. Allg. Chem. [Journal of Inorganic Chemistry and General Chemistry] 1999, 625, 1573.

[0147] Table 1 :Co x Ni 1-x Characteristic reflections of Co, Li2CO3, LiAlO2 and MnO (position given in °2θ and relative intensity in %), where the intensity of Cu Kα1 radiation is >10% and 2θ<80°:

[0148] Compound HkD 2θ[%] Relative strength [%] <![CDATA[Co 0.5 In 0.5 ]]> 1 1 1 44.36 100 2 0 0 51.68 46 2 2 0 76.12 24 Ni 1 1 1 44.50 100 2 0 0 51.84 46 2 2 0 76.38 24 Co 1 0 0 41.74 25 0 0 2 44.62 27 1 0 1 47.60 100 1 0 2 62.74 13 1 1 0 76.20 14 <![CDATA[Li2CO3]]> 1 1 0 21.24 100 2 0 0 23.30 19 2 0-2 30.44 98 0 0 2 31.76 96 1 1-2 34.00 83 3 1-1 36.72 81 0 2 1 39.44 39 2 2-1 42.48 22 3 1 1 48.58 52 4 2-1 57.34 11 2 2-3 57.90 19 2 0-4 59.58 20 5 1-3 62.86 12 <![CDATA[LiAlO2]]> 0 0 3 18.72 100 1 0 1 37.60 17 1 0 4 45.22 98 1 0 7 59.30 17 0 1 8 65.02 23 1 1 0 66.76 27 MnO 1 1 1 34.94 60 2 0 0 40.58 100 2 2 0 58.72 58 3 1 1 70.20 23 2 2 2 73.82 17

[0149] In case characteristic reflections overlapped with reflections of different crystalline phases (especially graphite, which contributed the largest fraction of the sample), additional measurements with alternative radiation sources were performed (eg Mo Ka instead of Cu Ka).

[0150] d) X-ray fluorescence (XRF)

[0151] In Examples 4 and 5, the metal, sulfur and phosphorus concentrations in the product were determined by XRF.

[0152] In Example 4, sulfur and metals were analyzed by XRF on pressed pellets (10 g sample and 2 g binder Fluxana Cereox) using a PANalytical AxiosmAX (PANalytical BV, Almelo, The Netherlands) wavelength dispersive X-ray fluorescence spectrometer WDXRF and PANalytical SuperQ 5 X-ray analysis software.

[0153] In Example 5, solid materials were measured as powder samples in polypropylene cuvettes. X-ray fluorescence measurements were performed using an energy dispersive Malvern PANalytical XRF spectrometer Epsilon 4DY6024. The data were evaluated by Malvern PANalytical's Omnian software.

[0154] Examples

[0155] In the following, three examples are described which illustrate the three steps of the process of the present invention leading to the final production of aluminum hydroxide (ie, before the refining step).

[0156] Example 1: Preparation of graphite / gypsum leaching residues

[0157] The pyrolyzed black material obtained from the market and having the composition shown in Table 2 was leached with a mixture of calcium hydroxide in water. The pyrolyzed black material was reduced to a large extent, i.e., the PXRD spectrum ( Figure 1 , black figure), it contains only a very small peak associated with lithium nickel cobalt manganese / aluminum oxide at a diffraction angle of 2q = 18.8° and a large peak associated with metallic nickel at 2q = 44.4°. For leaching, the reactor was first flushed with nitrogen. Then, water was fed into the reactor, followed by calcium hydroxide (from Schaefer Lime Co., Ltd. ( Kalk GmbH & Co. KG)'s Precal 50S). The formulation data for calcium hydroxide leaching are summarized in Table 3. The black substance as a solid is carefully added to the slurry of the slaked lime. Afterwards, the reaction mixture is heated to 98°C and kept at this temperature for 6h under stirring. Further subsequently, the heating of the container is stopped, and some water is evaporated by applying a vacuum until the reactor contents are cooled to 70°C. The reaction mixture is then filtered through a heated suction filter (wall temperature 65°C-70°C). The filter residue is cooled to ambient temperature in the filter and washed with deionized water until the lithium concentration in the wash filtrate is 3% of the concentration in the filtrate (0.44%). The filter cake is partially dried by flushing with nitrogen for 6h. The filter cake has an average water content of 31%, and its elemental composition is given in Table 4.

[0158] Table 2: Composition of black materials used in Example 1. The concentrations of metals and phosphorus were measured using ICP-OES, while fluorine, sulfur and carbon were measured as described above.

[0159] C F S Al Ca Co Cu Fe Li Mn Ni P wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% 35.9 2.4 0.01 5.4 0.13 6.2 3.8 0.3 3.7 0.43 22.7 0.52

[0160] Table 3: Composition of reactor feed for calcium hydroxide leaching of Example 1.

[0161] water Calcium hydroxide Black matter wt% wt% wt% 82.8 4.8 12.4

[0162] Table 4: Composition (dry mass) of the dried calcium hydroxide leaching residue obtained in Example 1. The concentrations of metals and phosphorus were measured using ICP-OES, fluorine was measured as described above, sulphur and carbon were measured by combustion.

[0163] C F S Al Ca Co Cu Fe Li Mn Ni P wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% 22.9 1.6 0.04 4.6 14.8 5.3 4.6 0.41 0.44 0.63 15.8 0.35

[0164] Example 2: Leaching of the residue of Example 1 by sulfuric acid

[0165] The filter cake obtained in Example 1 was leached by sulfuric acid to extract the metal components. Thus, the filter cake was mixed with water in a reactor that had been flushed with nitrogen before. Sulfuric acid (95%) was carefully added to the slurry under stirring. Afterwards, a solution of 30% hydrogen peroxide in water was carefully added, and the composition of the reactor feed is summarized in Table 6. Afterwards, the reaction mixture was heated to 90°C and maintained at this temperature for 5h. Finally, the reaction mixture was cooled to 50°C and filtered. The leached residue was washed until the Ni content in the wash filtrate reached a value lower than 0.2% of the Ni concentration in the filtrate. The composition of the sulfuric acid leaching residue is given in Table 7.

[0166] Table 6: Composition of reactor feed in Example 2.

[0167] water Leaching residue sulfuric acid Hydrogen Peroxide wt% wt% wt% wt% 74 12 12 2

[0168] Table 7: Composition (dry mass) of the leached residue of Example 2. The concentrations of metals and phosphorus were measured using ICP-OES, fluorine, sulfur and carbon were measured as described above.

[0169] C F S Al Ca Co Cu Fe Li Mn Ni P wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% 27.8 0.1 11.8 1.6 15.6 0.06 0.02 0.02 0.01 0.02 0.37 <0.01

[0170] The values ​​shown in Table 7 show that the dried leach residue consists of 29.3% carbon and 60.2% CaSO4, which may still contain some hydrate water. The leach residue has an acidic pH of about 2.

[0171] Example 3: Flotation

[0172] The washed acid leaching residue obtained in Example 2 was subjected to flotation experiments.

[0173] Example 3a: For this purpose, 202.7 g of the leaching residue, corresponding to 129 g of dry mass of material, were suspended in 1250 g of tap water. The suspension was stirred at 1250 rpm with the air valve closed in a 1.4 l laboratory scale Denver flotation cell. The collector Shellsol D40 (which is a hydrogenated C9-C 2-hydroxy-1-nitropropene) was added in an amount of 1 g corresponding to a collector concentration of 5000 g / t relative to the dry mass of the feed material. 11Isoalkane / cycloalkane mixture with less than 2% aromatics) was used as the collector. The mixture containing the collector was stirred for 10 min, and then the air valve of the Denver cell was opened to allow an air flow of approximately 250 l / h. The contents of the cell immediately produced foam, which was captured by periodically seeping it from the liquid surface. After 9 min of flotation time, an additional 250 g of water was added to raise the liquid level, but no more foam could be captured. The total flotation time was 15 min. The captured foam and tailings were filtered and dried in vacuum at 80°C to obtain 34.6 g and 95.0 g dry masses, respectively.

[0174] Example 3b: The procedure of Example 3a was repeated with a slightly different feed mass of 197.5 g corresponding to a dry mass of 124 g and 0.6 g of collector corresponding to 4800 g / t. The air flow was reduced to about 150 l / h to avoid very strong foaming at the beginning of the experiment. The weights of the concentrate and tailings after drying were 32.9 g and 91.8 g, respectively.

[0175] The results of flotation examples 3a and 3b are summarized in Table 8.

[0176] Table 8: Composition of concentrates and tailings for Examples 3a and 3b (recoveries in brackets). Metal and phosphorus concentrations were measured by ICP-OES, fluorine, sulfur and carbon were measured as described above.

[0177]

[0178] The recovery of gypsum in the tailings was obtained by subtracting the sulfur and calcium recoveries in the foam from 100%, which was 93.1% (based on sulfur).

[0179] Example 4: Freiberg flotation

[0180] This froth flotation method is intended to separate graphite particles (C element) from gypsum particles (Ca and S elements).

[0181] Example 4a: 1286.05 g of the leaching residue obtained in Example 2 were dispersed in 9320.58 g of tap water in a 16 l Outotec laboratory flotation cell GTK. 1 g of kerosene and 400 μl of methyl isobutyl carbinol (MIBC) were added as collector and frother, respectively, and the cell contents were floated at a rotor speed of 1000 rpm. The air flow rate was 300 l / h and the scraping frequency was 0.0625 1 / sec. A total of 382.55 g (dry mass) of concentrate was captured in 8.6 min. After this roughing stage, the tailings (903.5 g dry mass) were left in the flotation cell and conditioned again with 0.3 g of kerosene and 150 μl of MIBC. Sweep flotation was then started at a rotor speed of 1000 rpm and an air flow rate of 300 l / h. From this scavenger flotation stage, a further 38 g of centrate (dry mass) and 865 g of tailings (dry mass) were recovered within 6 min.

[0182] Example 4b: 2031.04 g of the leaching residue obtained in Example 2 were dispersed in 9534.72 g of tap water in a 16 l Outotec laboratory flotation cell GTK. 1 g of kerosene and 400 μl of methyl isobutyl carbinol (MIBC) were added as collector and frother, respectively, and the cell contents were floated at a rotor speed of 1000 rpm. The air flow rate was 300 l / h and the scraping frequency was 0.0625 1 / sec. Similar to Example 3a, the roughing and scavenging stages were combined. A total of 459.13 g (dry mass) of combined roughing and scavenging concentrate and 1571.91 g of tailings were captured. Thereafter, the combined concentrate was resuspended in a flotation cell, 0.3 g of kerosene and 150 μl of MIBC were added and flotation was then started at a rotor speed of 1000 rpm and an air flow rate of 300 l / h. From this clean flotation stage, a further 383.62 g of centrate (dry mass) and 75.51 g of tailings (dry mass) were recovered in 31 min.

[0183] The results of Examples 4a and 4b are summarized in Table 9.

[0184] Table 9: Composition of concentrates and tailings of Examples 4a and 4b (recoveries in brackets); metal, sulfur and phosphorus concentrations were measured by XRF, carbon was measured as described above.

[0185]

[0186] *All yield data are related to feed quality

[0187] The recovery of gypsum in the tailings was obtained by subtracting the recovery of sulfur and calcium in the foam from 100%, i.e., 89.3% for Example 4a and 99.9% for Example 4b (each based on sulfur).

[0188] Example 5

[0189] The washed acid leaching residue obtained in Example 2 but having the composition shown in Table 10 was subjected to a separation experiment using magnetic separation using a magnetic carrier body. For this purpose, 20 g (dry mass) of the leaching residue was suspended in 60 g of tap water. The suspension was depolymerized by treatment with an UltraTurrax UT25 at 10000 rpm for 5 min. During this treatment, the pH value was adjusted to 3 by adding a NaOH solution. 0.5 g of Shellsol D40 was added to the suspension and homogenized by stirring at 10000 rpm for an additional 5 min with an UltraTurrax UT25. To this suspension was added 0.6 g of hydrophobized magnetite (prepared according to Example 1 of WO 2015 / 110555, based on magnetite particles with D50 4 μm and polyorganosiloxane (solid methyl silicone resin, Mp 35°C-55°C, with an approximate molecular weight Mw of about 6700 g / mol [CH3SiO 1.5 ] 100 The average composition of ()) was suspended in a suspension of 3.6 g of an aqueous solution of 0.1% Lutensol XL80 in water and stirred for 15 min at 1400 rpm with a pitched blade paddle stirrer. The suspension was then pumped at a rate of 6 l / h to a laboratory-scale magnetic separator Eriez LH4 equipped with a 4 x 1 mm wedge-shaped wire mesh matrix at a magnetic field strength of 0.7 T. Thereafter, the matrix was rinsed with water to completely recover the non-magnetic fraction. The magnetic field was then turned off and the magnetic fraction was rinsed from the matrix with water. 5.43 g of the magnetic fraction (concentrate) and 13.36 g of the non-magnetic (tailings) were thus recovered (all dry mass). The results of Example 5 are summarized in Table 11.

[0190] Table 10: Composition (dry mass) of the sulfuric acid leaching residue employed in Example 4. Metal and phosphorus concentrations were measured by ICP-OES, fluorine, sulfur and carbon were measured as described above.

[0191] C F S Al Ca Co Cu Fe Mn Ni P wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% wt% 23.2 0.1 12.7 6.4 9.8 0.06 0.25 0.06 1 0.64 0.51

[0192] Table 11: Composition of the concentrate (magnetite has been subtracted by calculation) and tailings (recoveries in brackets) of Example 5; metal, sulfur and phosphorus concentrations were measured by XRF, carbon was measured as described above.

[0193]

[0194] The recovery of gypsum in the tailings was obtained by subtracting the sulfur and calcium recoveries in the foam from 100%, which was 61.9% (based on sulfur).

Claims

1. A method for recycling carbon and sparingly soluble alkaline earth metal sulfate from leaching residues, the method comprising the following steps: In the alkaline earth metal contact step, the lithium battery material is contacted with a material containing an alkaline earth metal in a solvent to produce an alkaline earth metal contacted lithium battery material; In a leaching step, the alkaline earth metal-contacted lithium battery material is leached in sulfuric acid to produce a leaching solution and the leaching residue, wherein the leaching residue contains carbon and the insoluble alkaline earth metal sulfate; separating the leaching residue from the leaching solution in a solid-liquid separation step; suspending the leach residue in a solvent in a suspending step to produce a suspended leach residue; contacting the suspended leaching residue with a plurality of at least one type of support bodies in a support contacting step, in At least a portion of the carbon contained in the suspended leaching residue is agglomerated with the plurality of at least one type of support bodies. Producing a suspension comprising Carbon-containing carrier bulk agglomerates and A non-agglomerate containing the sparingly soluble alkaline earth metal sulfate, or among them At least a portion of the sparingly soluble alkaline earth metal sulfate contained in the suspended leaching residue is agglomerated with the plurality of at least one type of support bodies. Producing a suspension comprising A carrier body agglomerate containing the insoluble alkaline earth metal sulfate and Carbonaceous non-agglomerates; At least a portion of the carrier body agglomerates are separated from the suspension in a solid-solid separation step.

2. The method according to claim 1, wherein: The alkaline earth metal is calcium, and the sparingly soluble alkaline earth metal sulfate is calcium sulfate.

3. The method according to claim 1 or 2, wherein: The lithium battery material is a pyrolyzed lithium battery material, preferably a black substance derived from the pyrolysis of a lithium battery.

4. A method according to any one of the preceding claims, wherein: The carbon is amorphous carbon, preferably selected from the list consisting of carbon black and pyrolytic coke; or crystalline carbon, preferably selected from the list consisting of graphite, fullerenes, buckyballs, nanotubes, and mixtures thereof, most preferably graphite.

5. A method according to any one of the preceding claims, wherein: The solid-liquid separation step is performed as a separation step according to one or more of the list consisting of a filtration step, a centrifugation step, a sedimentation step and a decantation step, preferably as a filtration step.

6. A method according to any one of the preceding claims, wherein: The solid-solid separation step is flotation and the carrier entities are gas bubbles from the carrier gas.

7. The method according to claim 6, wherein: The carrier gas is a gas that is inert to the suspension, preferably air.

8. The method according to claim 6 or 7, wherein: The flotation is carried out in a mechanical flotation cell, in a pneumatic flotation cell or in a column flotation cell or in a combination of at least two of these cells.

9. A method according to any one of the preceding claims, wherein: The solid-solid separation step is a magnetic separation and the carrier entities are magnetic particles.

10. The method according to claim 9, wherein: The separated support body agglomerates are disrupted, thereby allowing these magnetic support bodies to be separated from the non-magnetic carbon or sparingly soluble alkaline earth metal sulfate particles by a magnetic separation step, preferably by treatment with a surfactant.

11. The method according to claim 9 or 10, wherein: These magnetic particles comprise hydrophobized magnetite, preferably magnetite hydrophobized using polyorganosiloxanes.

12. A method according to any one of the preceding claims, wherein: In the support contacting step, the pH of the solvent is adjusted to a pH above 3, preferably in the range of 3 to 8, before adding the support bulk.

13. The method according to claim 12, wherein: The pH is adjusted by adding a base selected from the list consisting of alkali metal hydroxides, alkali metal carbonates, ammonium hydroxide, alkaline earth metal hydroxides, alkaline earth metal carbonates or mixtures thereof, preferably at least one alkali metal hydroxide, preferably sodium hydroxide.

14. A method according to any one of the preceding claims, wherein: The support contacting step includes adding a collector and optionally a frother.

15. The method according to claim 14, wherein: The collector is selected from non-polar hydrocarbons, preferably non-polar aliphatic hydrocarbons, and most preferably C9 to C 17 Aliphatic non-polar hydrocarbons.

16. The method according to claim 14 or 15, wherein: The foaming agent is a surfactant, preferably an organic heteropolar compound, more preferably an alcohol or a polyethylene glycol ether, and most preferably methyl isobutyl carbinol (MIBC).

17. Graphite obtainable by the method according to any one of the preceding claims 1 to 16.

18. Barium sulfate obtainable by the method according to any one of the preceding claims 1 to 16.

19. Calcium sulfate obtainable by the method according to any one of the preceding claims 1 to 16.

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