WO2024188770A1

WO2024188770A1 - Method for purifying leach solutions

Info

Publication number: WO2024188770A1
Application number: PCT/EP2024/055904
Authority: WO
Inventors: Maximilian RANG; Wolfram WILK; Marc DUCHARDT; Anne-Marie Caroline ZIESCHANG; Fabian Seeler; Wolfgang Rohde; Kerstin Schierle-Arndt; Vincent Smith; Alexej Michailovski; Andreas Melzer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2023-03-10
Filing date: 2024-03-06
Publication date: 2024-09-19
Anticipated expiration: 2025-09-10
Also published as: TW202446968A

Abstract

The invention refers to a method for purifying a leach solution of a material, such as a battery material, wherein the method comprises providing a leach mixture by contacting the material with an acidic aqueous solution, filtering off the leach mixture through a filter means comprising a surface-active adsorbant with hydroxyl groups, to obtain a residue and as a supernatant a purified leach solution in the form of an aqueous solution comprising metal ions. The invention also relates to processes for separating various metals and metal compounds from a material such as, for example, a battery material, and processes for recycling lithium ion battery materials.

Description

BASF SE

67056 Ludwigshafen am Rhein

Method for purifying leach solutions

Field of the invention

The present disclosure relates to processes for purifying a leach solution of a material such as, for example, a battery material, processes for separating various metals and metal compounds from a material such as, for example, a battery material, and processes for recycling lithium ion battery materials.

Background

High purity lithium is a valuable resource. Many sources of lithium, such as lithium ion batteries, lithium ion battery waste, lithium containing water, e.g. ground water, and raw lithium containing ores, are complex mixtures of various elements and compounds. The removal and purification of lithium from a material, such as a lithium ion battery material, are exemplary steps in the recycling of lithium ion batteries. Lithium ion battery materials are complex mixtures of various elements and compounds, and it may be desirable to remove various non-lithium impurities. Such impurities may exist in a variety of oxidation states which may impact, for example, the efficiency of a leaching process. For example, in some leaching processes high oxidation state metals may be more or less efficiently leached than low or zero oxidation state metals. Some non-lithium impurities are also valuable resources, and it may additionally be desirable to separate and purify various elements and compounds from such materials.

Accordingly, there is a need for leaching methods for efficiently and effectively leaching complex mixtures of various elements and compounds such as, for example, mixed metals coexisting in a variety of oxidation states. For example, there is a need for economic processes with high lithium recovery and high lithium purity. There is also a need for economic processes with high recovery and high purity for removing value metals such as, for example, nickel and cobalt, from materials.

WO 2021/174348 A1 discloses a method for processing a black mass material from lithium iron phosphate batteries comprising a) receiving a black mass material feed material; b) acid leaching the black mass material at a pH that is less than 4, thereby producing a pregnant leach solution (PLS) comprising at least 80% of the lithium from the black mass feed material, and at least a portion of the iron and the phosphorous from the black mass feed material; providing a first intermediary solution after completing step b); and separating at least 90% of the iron and the phosphorous from the first intermediary solution to provide an output solution.

DE 10 2006 040 899 A1 describes a method for recovering gold or silver by leaching out a gold or silver ore using a cyanide alkaline solution to produce a first aqueous solution, filtering the solution to remove the leached ore, treating the filtrate using elemental zinc to produce a second aqueous solution containing finely dispersed metallic gold or silver and filtering the second aqueous solution to remove the metallic gold or silver using a fibrous organic filtering aid.

WO 2014/164127 A1 refers to a nonwoven filtration medium that includes a fibrous base media including synthetic and/or natural fibers and micro fibrillated cellulose fibers.

However, in some leaching processes undesired emulsification may occur which may impact, for example, the efficiency of separation processes following the respective leaching processes. Accordingly, there is a need for processes for removing, at least partially, undesired emulsifiers from a respective leach solution of a material, thus, rendering the respective subsequent separation processes still more efficient and effective. Summary of the invention

Disclosed herein are methods for purifying a leach solution of a material, the material comprising one or more chosen from metal oxides, metal hydroxides, metal carbonates and combinations thereof. In some embodiments, the material also comprises one or more metals in a zero oxidation state. Each such method comprises providing a leach mixture by contacting the material at a temperature ranging from 20°C to 110°C for a total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution having a pH less than 6 and comprising one or more acids chosen, for example, from HCI, H2SO4, CH3SO3H, HNO3, and filtering off the leach mixture through a filter means comprising a surfaceactive adsorbant with hydroxyl groups, to obtain a residue and as a supernatant, such as a filtrate, a purified leach solution in the form of an aqueous solution comprising metal ions.

Also disclosed are methods comprising leaching a material by processing the material as described before to obtain an aqueous solution comprising metal ions, and separating the metal ions to obtain at least one essentially pure metal ion solution and/or at least one essentially pure solid metal ion salt.

Further disclosed are methods comprising mechanically comminuting at least one material chosen from a lithium ion battery, lithium ion battery waste, lithium ion battery production scrap, lithium ion cell production scrap, lithium ion cathode active material, and combinations thereof to obtain a black mass, and leaching the black mass by processing the black mass as described before.

Detailed description

Disclosed herein are methods for purifying a leach solution of a material, the material comprising one or more chosen from metal carbonates, metal oxides, metal hydroxides, and combinations thereof. In some embodiments, the material also comprises one or more metals in a zero oxidation state. Each such method comprises providing a leach mixture by contacting the material at a temperature ranging from 20°C to 110°C for a total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution having a pH less than 6 and comprising one or more acids chosen, for example, from HCI, H2SO4, CH3SO3H, HNO3, and filtering off the leach mixture through a filter means comprising a surface-active adsorbant with hydroxyl groups, to obtain a residue and as a supernatant, i.e. as a filtrate, a purified leach solution in the form of an aqueous solution comprising metal ions.

In some embodiments, the acidic aqueous solution comprises at least one acid chosen from HCI, H2SO4, CH3SO3H, HNO3, and combinations thereof. In some embodiments, the acidic aqueous solution further comprises one or more chosen from O2, N₂O, and combinations thereof.

In some embodiments, the leach mixture may be a leach solution, e.g. a pregnant leach solution (PLS), providing of which already includes a filtering step, i.e. a filtering step preceding the filtering step according to the invention. In some embodiments, the leach mixture may be a leach suspension, providing of which does not necessarily require a filtering step preceding the filtering step according to the invention.

In some embodiments, the acidic aqueous solution comprises H₂SO₄. In some embodiments, the acidic aqueous solution comprises H₂SO₄ and O₂. In some embodiments, the acidic aqueous solution comprises O₂ and the O₂ is provided as air. In some embodiments, the acidic aqueous solution comprises sulfur dioxide, SO₂. In some embodiments the acidic aqueous solution comprises less than or equal to 3 volume % sulfur dioxide. In some embodiments, the acidic aqueous solution comprises air with less than or equal to 3 volume % sulfur dioxide.

In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 causes a formation of hydrogen gas, and an oxidizing agent chosen from O₂ (e.g., air), N₂O, and combinations thereof is added after the formation of hydrogen gas.

In some embodiments, the one or more chosen from metal oxides or metal hydroxides comprising nickel, cobalt, or manganese contain these metals in an oxidation state of +2 in an amount ranging from 5 weight % to 10 weight %, 10 weight % to 20 weight %, or 20 weight % to 50 weight %, relative to the total weight of the one or more chosen from metal oxides or metal hydroxides comprising nickel, cobalt, or manganese.

The wordings "weight %" and "weight percent" and "weight ratio" are used synonymously herein.

In some embodiments, the acidic aqueous solution has a concentration of acid ranging from 18 mol/L to 0.0001 mol/L.

In some embodiments, contacting the material at a temperature ranging from 20°C to 110°C for the total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution comprises: suspending the material in deionized water to obtain a intermediary suspension, subsequently treating the intermediary suspension, for example dropwise, with an amount of one or more of the acids chosen, for example, from HCI, H₂SO₄, CH3SO3H, HNO₃, and combinations thereof, to obtain a reaction mixture.

In some embodiments, the reaction mixture corresponds to the leach mixture.

In some embodiments, contacting the material at a temperature ranging from 20°C to 110°C for the total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution further comprises stirring the reaction mixture first under inert gas and then under aerobic conditions, and adding to the reaction mixture one or more oxidants chosen from O₂, N₂O, and combinations thereof, to obtain the leach mixture.

In some embodiments, contacting the material at a temperature ranging from 20°C to 110°C for the total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution further comprises stirring the reaction mixture first under inert gas and then under aerobic conditions, and adding one or more reductants and/or a base, to obtain the leach mixture.

In some embodiments, contacting the material at a temperature ranging from 20°C to 110°C for the total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution further comprises stirring the reaction mixture first under inert gas and then under aerobic conditions, and adding to the reaction mixture one or more oxidants, and adding one or more reductants and/or a bas, to obtain the leach mixture.

As used herein, a purified leach solution is a leach solution essentially free from emulsifiers and/or dispersion reagents, which is shown, for example, by the fact that the time until a phase separation occurs after adding an organic solvent and shaking the resulting two-phase system, is less than 2 minutes.

In some embodiments, the filter means comprising a surface-active adsorbant with hydroxyl groups is a porous glass filter medium. In some embodiments, the filter means comprising a surface-active adsorbant with hydroxyl groups is a cellulose containing filter medium. In some embodiments, the porous glass filter medium is a glass frit. Such a glass frit on an industrial scale is based on glass fibers and is particularly suitable for small quantities of solids.

In the process on which the invention is based, large quantities of solids are first separated using conventional separation / filter methods. That means that the preparation of the material whose leach solution is to be purified by the method according to the invention has already been preceded by separation methods, e.g. filter methods by which large quantities of solids have been removed. By means of the porous glass filter medium or the cellulose containing filter medium emulsifying agents and/or dispersion reagents are to be removed from the provided leach mixture. In some embodiments, the used filter media are single-use filters.

In some embodiments, the cellulose containing filter medium is a filter paper. In some embodiments, the filter paper is a fluted filter paper.

In some embodiments, the cellulose containing filter medium is a filter cloth. In some embodiments, such a filter cloth is used in a known manner in combination with a filter press.

In some embodiments, the leach mixture is filtered off through a porous glass filter medium via vacuum filtration. In some embodiments, the leach mixture is filtered off through a glass frit via vacuum filtration.

In some embodiments, the leach mixture is filtered off through a cellulose containing filter medium via gravity filtration. In some embodiments, the leach mixture is filtered off through a filter paper via gravity filtration. In some embodiments, the leach mixture is filtered off through a filter cloth via gravity filtration by applying appropriate pressure. In some embodiments, the filter means have a cellulose content of greater than or equal to 50 weight percent (weight %) in relation to the total weight of the filter means. In some embodiments, the filter means have a cellulose content of greater than or equal to 80 weight % in relation to the total weight of the filter means. In some embodiments, the filter means have a cellulose content of greater than or equal to 90 weight % in relation to the total weight of the filter means. It has been shown that components of the leach mixture containing Si, O and/or C attach to the hydroxyl groups. It could be demonstrated that Si was significantly depleted after a filtering using the filter means comprising a surface-active adsorbant with hydroxyl groups.

In some embodiments, the leach mixture is filtered off through a glass frit via vacuum filtration.

In some embodiments, the glass frit has a porosity of P40, P16 or P1.6 according to the standard ISO 4793-80, e.g. a pore size in the range of about 10 to 40 micrometer (P40) or a pore size in the range of about 10 to 16 micrometer (P16) or a pore size in the range of about 1 to 1.6 micrometer (P1.6).

In some embodiments, the leach mixture is filtered off through a filter paper via gravity filtration. In some embodiments, the filter paper is a fluted filter paper.

In some embodiments, the filter paper is a wet strength filter paper with a cellulose content in the range of 50 weight percent to 95 weight percent, wherein each weight percent is by total weight of the filter paper.

In some embodiments, the filter cloth has a cellulose content in the range of 50 weight percent to 95 weight percent, wherein each weight percent is by total weight of the filter cloth. In some embodiments, the material is a battery material, the battery material being a lithium ion battery material comprising one or more chosen from black mass, cathode active material, cathodes, cathode active material precursors, and combinations thereof, and/or wherein the battery material comprises one or more chosen from nickel, cobalt, manganese, and combinations thereof.

In some embodiments, the material comprises one or more metals in a zero oxidation state, the one or more metals in a zero oxidation state being chosen from nickel, cobalt, copper, aluminium, iron, manganese, rare earth metals, and combinations thereof. In some embodiments, the metal carbonates are chosen from lithium carbonates. In some embodiments, the metal oxides are chosen from nickel oxides, cobalt oxides, copper oxides, aluminium oxides, iron oxides, manganese oxides, rare earth oxides, and combinations thereof. In some embodiments, the metal hydroxides are chosen from lithium hydroxides, nickel hydroxides, cobalt hydroxides, copper hydroxides, aluminium hydroxides, iron hydroxides, manganese hydroxides, alkaline earth hydroxides, rare earth hydroxides, and combinations thereof.

In some embodiments, the material is chosen as a battery material that comprises: from 0.1 weight percent to 10 weight percent lithium, from 0 weight percent to 60 weight percent nickel, from 0 weight percent to 20 weight percent cobalt, from 0 weight percent to 20 weight percent copper, from 0 weight percent to 20 weight percent aluminium, from 0 weight percent to 20 weight percent iron, and from 0 weight percent to 20 weight percent manganese; wherein each weight percent is by total weight of the battery material.

In some embodiments, a disclosed method comprises subjecting the at least one material to a heat treatment step. In some embodiments, the material, such as for example a battery material or a precursor thereof, is pyrolysed prior to contacting the material with the acidic aqueous solution.

In some embodiments, the acidic aqueous solution comprises O₂, the O₂ being provided as air, and the air being sparged through the acidic aqueous solution.

Also disclosed is a method comprising processing a material according to an embodiment of the previously described inventive method to obtain an aqueous solution comprising metal ions, and separating the metal ions to obtain at least one essentially pure metal ion solution and/or at least one essentially pure solid metal ion salt.

In some embodiments separating the metal ions comprises one or more of a solid/liquid separation, an extraction, a precipitation, a crystallization, and combinations thereof.

Further disclosed is a method comprising: mechanically comminuting at least one material such as, for example, a battery material chosen from a lithium ion battery, lithium ion battery waste, lithium ion battery production scrap, lithium ion cell production scrap, lithium ion cathode active material, and combinations thereof to obtain a black mass, and subjecting the black mass to a method according to an embodiment of the previously described inventive methods.

Definitions:

As used herein, “a” or “an” entity refers to one or more of that entity, e.g., “a compound” refers to one or more compounds or at least one compound unless stated otherwise. As such, the terms “a” (or “an”), “one or more”, and “at least one” are used interchangeably herein. As used herein, the term “material” refers to the elements, constituents, and/or substances of which something is composed or can be made.

As used herein, an “acidic aqueous solution” is an aqueous solution having a pH less than 7 capable of oxidizing a metal in a zero oxidation state. For example, some acidic aqueous solutions are capable of oxidizing some metals in a zero oxidation state but not others.

As used herein, an “oxidizing agent” is a compound capable of oxidizing a metal in a zero oxidation state. For example, some oxidizing agents are capable of oxidizing some metals in a zero oxidation state but not others.

As used herein, a “solution” is a combination of a fluid and one or more compounds. For example, each of the one or more compounds in the solution may or may not be dissolved in the fluid.

As used herein, an “essentially pure metal ion solution” is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 50% by weight excluding the weight of solvent.

As used herein, an “essentially pure solid metal ion salt” is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 50% by weight of the solid excluding the weight of solvent.

As used herein, the term “sparging” refers to dispersing a gas through a liquid.

As used herein, the term ’’base” refers to a material capable of reacting with a hydronium ion and to increase the pH-value of an acidic solution. Materials:

The material comprises one or more metals in a zero oxidation state and one or more chosen from metal oxides, metal hydroxides, and combinations thereof.

In some embodiments, the material comprises one or more chosen from lithium, nickel, cobalt, manganese, and combinations thereof.

In some embodiments, the one or more metals in a zero oxidation state is chosen from nickel, cobalt, copper, aluminum, iron, manganese, rare earth metals, and combinations thereof.

In some embodiments, the metal carbonates are chosen from lithium carbonates.

In some embodiments, the metal oxides are chosen from nickel oxides, cobalt oxides, copper oxides, aluminum oxides, iron oxides, manganese oxides, rare earth oxides, and combinations thereof.

In some embodiments, the metal hydroxides are chosen from lithium hydroxides, nickel hydroxides, cobalt hydroxides, copper hydroxides, aluminum hydroxides, iron hydroxides, manganese hydroxides, alkaline earth hydroxides, rare earth hydroxides, and combinations thereof.

In some embodiments, the material comprises: from 0.1 weight percent to 10 weight percent lithium, from 0 weight percent to 60 weight percent nickel, from 0 weight percent to 20 weight percent cobalt, from 0 weight percent to 20 weight percent copper, from 0 weight percent to 20 weight percent aluminum, from 0 weight percent to 20 weight percent iron, and from 0 weight percent to 20 weight percent manganese; wherein each weight percent is by total weight of the material. In some embodiments, the material, or a precursor thereof, is pyrolyzed prior to be processed by an embodiment of the inventive methods. In some embodiments, the pyrolysis is performed under an inert atmosphere, an oxidizing atmosphere, a reducing atmosphere, or a combination thereof.

In some embodiments, the material has a weight ratio ranging from 0.01 to 10, 0.01 to 5, 0.01 to 2, or 0.01 to 1 of lithium to a total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus.

In some embodiments, the material is a lithium ion battery material comprising one or more chosen from black mass, cathode active material, cathodes, cathode active material precursors, and combinations thereof.

“Black mass” refers to materials comprising lithium derived from, for example, a lithium ion battery, lithium ion battery waste, lithium ion battery production scrap, lithium ion cell production scrap, lithium ion cathode active material, and/or combinations thereof by mechanical processes such as mechanical comminution. For example, black mass may be derived from battery scrap by mechanically treating the battery scrap to obtain the active components of the electrodes such as graphite and cathode active material and may include impurities from the casing, electrode foils, cables, separator, and electrolyte. In some examples, the battery scrap may be subjected to a heat treatment to pyrolyze organic (e.g. electrolyte) and polymeric (e.g. separator and binder) materials. Such a heat treatment may be performed before or after mechanical comminution of the battery material. In some embodiments, the black mass is subjected to a heat treatment.

Lithium ion batteries may be disassembled, punched, milled, for example in a hammer mill, rotor mill, and/or shredded, for example in an industrial shredder. From this kind of mechanical processing the active material of the battery electrodes may be obtained. A light fraction such as housing parts made from organic plastics and aluminum foil or copper foil may be removed, for example, in a forced stream of gas, air separation or classification or sieving.

Battery scraps may stem from, e.g., used batteries or from production waste such as off-spec material. In some embodiments a material is obtained from mechanically treated battery scraps, for example from battery scraps treated in a hammer mill a rotor mill or in an industrial shredder. Such material may have an average particle diameter (D₅₀) ranging from 1 pm to 1 cm, such as from 1 pm to 500 pm, and further for example, from 3 pm to 250 pm.

Larger parts of the battery scrap like the housings, the wiring and the electrode carrier films may be separated mechanically such that the corresponding materials may be excluded from the battery material that is employed in the process.

Mechanically treated battery scrap may be subjected to a solvent treatment in order to dissolve and separate polymeric binders used to bind the transition metal oxides to current collector films, or, e.g., to bind graphite to current collector films. Suitable solvents are N-methylpyrrolidone, N,N-dimethyl- formamide, N,N-dimethylacetamide, N-ethylpyrrolidone, and dimethylsulfoxide, in pure form, as mixtures of at least two of the foregoing, or as a mixture with 1 % to 99 % by weight of water.

In some embodiments, mechanically treated battery scrap may be subjected to a heat treatment in a wide range of temperatures under different atmospheres.

In some embodiments, the heat treatment is performed at a temperatures ranging from 350°C to 900°C. In some embodiments, the heat treatment is performed at a temperatures ranging from 450°C to 800°C. In some embodiments, the heat treatment is performed under an inert, oxidizing, or reducing atmosphere. In some embodiments, the heat treatment is performed under an inert or reducing atmosphere. In some embodiments, reducing agents are formed under the conditions of the heat treatment from pyrolyzed organic (polymeric) components. In some embodiments, reducing agents are formed by adding a reducing gas such as H₂ and/or CO.

In some embodiments, the material comprises at least one chosen from lithiated nickel cobalt manganese oxide, lithiated nickel cobalt aluminum oxide, lithium metal phosphate, lithium ion battery scrap, a black mass, and combinations thereof.

In some embodiments, the material comprises lithium metal phosphate of formula Li_xMPO₄, wherein x is an integer greater than or equal to one, and M is chosen from metals, transition metals, rare earth metals, and combinations thereof.

In some embodiments, the material comprises nickel, cobalt, manganese, copper, aluminum, iron, phosphorus, or combinations thereof.

In some embodiments, the material has a weight ratio ranging from 0.01 to 10 of lithium to a total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus. In some embodiments, the material has a weight ratio ranging from 0.01 to 5 of lithium to a total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus. In some embodiments, the material has a weight ratio ranging from 0.01 to 2 of lithium to a total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus. In some embodiments, the material has a weight ratio ranging from 0.01 to 1 of lithium to a total weight of nickel, cobalt, manganese, copper, aluminum, iron, and phosphorus.

In some embodiments, the material comprises Li_xMO2, wherein x is an integer greater than or equal to one, and M is chosen from metals, transition metals, rare earth metals, and combinations thereof.

In the scope of the present disclosure, the terms "supernatant" and "filtrate" are used synonymously. Leach solution:

The method for purifying a leach solution of a material comprises: providing a leach mixture by contacting the material with an acidic aqueous solution having a pH less than 6, the material comprises one or more metals in a zero oxidation state and one or more chosen from metal oxides, metal hydroxides, and combinations thereof.

The acidic aqueous solution comprises one or more acids chosen from HCI, H2SO4, CH3SO3H, HNO3, and combinations thereof. In some embodiments, the acidic aqueous solution comprises at least one chosen from H₂SO₄, O₂, N₂O, and combinations thereof. In some embodiments, the acidic aqueous solution comprises H₂SO₄. The acidic aqueous solution further comprises one or more chosen from O₂, N₂O, and combinations thereof. In some embodiments, the acidic aqueous solution comprises an acid that is also an oxidizing agent such as, for example, H₂SO₄. In some embodiments, the acidic aqueous solution comprises an oxidizing agent that is not an acid such as, for example, O₂, N₂O, or combinations thereof. In some embodiments, the acidic aqueous solution comprises an acid and an oxidizing agent. In some embodiments, the acidic aqueous solution comprises an acid that is also an oxidizing agent and further comprises an oxidizing agent that is not an acid.

In some embodiments, one or more chosen from metal oxides, metal hydroxides, and combinations thereof are reduced by adding a reducing agent. In some embodiments, the reducing agent is one or more chosen from SO₂, metabisulfite salts, bisulfite salts, thiosulfate salts, dithionate salts, H₂O₂, H₂, and combinations thereof.

In some embodiments, a black mass is slurred in water at a weight percentage of black mass by total weight of the slurry ranging from 5% to 30%. In some embodiments, the slurred black mass as the material is contacted with the acidic aqueous solution having a pH less than 6. In some embodiments, the acidic aqueous solution having a pH less than 6 is formed from the slurred black mass by addition of acid which is also to be understood as the step of contacting the material with the acidic aqueous solution having a pH less than 6 and comprising one or more acids in accordance with the method of the present invention. In some embodiments, the weight ratio of H2SO4 in the acidic aqueous solution to black mass ranges from 1 :1 to 2:1. In some embodiments, H2SO4 is added to adjust the pH during the contacting step.

In some embodiments, the black mass is provided as a slurry. In some embodiments, the black mass is provided as a slurry in water. In some embodiments, the black mass is provided as a slurry in aqueous side streams from subsequent treatment steps such as, for example, washing liquids from filters. In some embodiments, the black mass is provided as a solid.

Contacting the material with an acidic aqueous solution is performed at a temperature ranging from 20°C to 1 10°C. In some embodiments, contacting the material with an acidic aqueous solution is performed for a duration ranging from 20 minutes to 10 hours.

In some embodiments, the acidic aqueous solution comprises air. In some embodiments, the air comprises less than or equal to 3 volume % sulfur dioxide. In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 comprises sparging air through the acidic aqueous solution. In some embodiments, the air is sparged through the acidic aqueous solution at a rate of up to 20% solution volume/min. In some embodiments, the air is sparged through the acidic aqueous solution at a rate in the range of from 0.1% to 20% solution volume/min. The rate refers to the volume of O2 being sparged through the acidic aqueous solution per minute, i.e., it is equal to approximately 21% of the volume of air being sparged through the solution.

In some embodiments, the acidic aqueous solution has a pH ranging from -1.0 to 3. In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 comprises first contacting the material with an acid and, subsequently, adding an oxidizing agent chosen from O₂, N₂O, and combinations. In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 comprises first contacting the material with an acid causing a formation of hydrogen gas and, subsequent to the formation of hydrogen gas (i.e., after the formation of hydrogen gas has subsided), adding an oxidizing agent chosen from O₂, N₂O, and combinations. In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 comprises first contacting the material with an acid causing a formation of hydrogen gas, monitoring the formation of hydrogen gas by gas chromatography and/or hydrogen sensors, and, subsequent to the formation of hydrogen gas (i.e., after the formation of hydrogen gas has subsided), adding an oxidizing agent chosen from O₂, N₂O, and combinations. In some embodiments, contacting the material with an acidic aqueous solution having a pH less than 6 comprises first contacting the material with an acid causing a formation of hydrogen gas, monitoring the formation of hydrogen gas by gas chromatography and/or hydrogen sensors, and, when the concentration of hydrogen gas is less than 5 volume %, for example less than 1 volume % for example less than 0.1 volume %, adding an oxidizing agent chosen from O₂, N₂O, and combinations.

In some embodiments, excess oxidizing gas O₂, such as in air, and/or N₂O is recycled from the off-gas back into the leaching reactor.

In some embodiments, the optional reducing agent comprises SO₂ and the SO₂ is sparged through the solution at a rate of up to 20% solution volume/min. In some embodiments, the SO₂ is sparged through the solution at a rate in the range of from 0.1% to 20% solution volume/min. In some embodiments, the SO₂ is sparged through the solution for 1 hour to 3 hours. In some embodiments, the optional reducing step is performed at ambient temperature.

In some embodiments, the method is performed batchwise.

In some embodiments, contacting the material with an acidic aqueous solution is carried out at ambient pressure. In some embodiments, contacting the material with an acidic aqueous solution is carried out at an elevated pressure.

In some embodiments, the contacting step is at a temperature ranging from 20°C to 110°C for a total time span ranging from 20 minutes to 10 hours.

The advantage of the purification method presented herein is that emulsifying agents and/or dispersion reagents present in the provided leach mixture are adsorbed, at least in part, by the filter means comprising a surface-active adsorbant with hydroxyl groups, and, therefore, these emulsifying agents and/or dispersion reagents can be extracted or separated from the leach mixture, leaving a purified leach solution. The purified leach solution can be subjected to further specific separation steps in order to separate targeted specific metal ions.

Such emulsifying agents present in the leach mixture may be from the group comprising Si, C, O, nanoparticles with a particle size < 500nm, gel-like SiOx networks, polysiloxane and derivates, organic residues from a previous pyrolysis of organic binders, and combinations thereof. In some cases, Si- containing surfactants are generated when a respective binder is not pyrolyzed sufficiently during a prior heat treatment of the material such as, for example, a black mass.

Nanoparticles with a particle size < 500nm may be e.g. SiO₂, Cu, intact CAM (cathode active material). Organic binders that are typically used in batteries are, e.g., PVDF (polyvinylidene fluoride), SBR (styrene-butadiene) and any combination thereof. Gel-like SiOx networks, polysiloxane and organic residues act themselves as emulsifying agents or as dispersion reagents which hold particles in suspension / dispersion.

In some embodiments, the method comprises purifying a leach solution of a material as disclosed herein to obtain an aqueous solution comprising metal ions and separating the metal ions to obtain at least one essentially pure metal ion solution and/or at least one essentially pure solid metal ion salt.

In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 50% by weight of the solid excluding the weight of solvent such as all water. In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 70% by weight of the solid excluding the weight of solvent. In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 80% by weight of the solid excluding the weight of solvent. In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 90% by weight of the solid excluding the weight of solvent. In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 95% by weight of the solid excluding the weight of solvent. In some embodiments, an essentially pure solid metal ion salt is a solid comprising a metal ion and a counter ion; wherein the total weight of the metal ion and counter ion is at least 99% by weight of the solid excluding the weight of solvent.

In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, and a solvent; wherein the total weight of the metal ion and counter ion is at least 50% by weight of the solution excluding the weight of solvent. In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 70% by weight of the solution excluding the weight of solvent. In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 80% by weight of the solution excluding the weight of solvent. In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 90% by weight of the solution excluding the weight of solvent. In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 95% by weight of the solution excluding the weight of solvent. In some embodiments, an essentially pure metal ion solution is a solution comprising a metal ion, a counter ion, a solvent; wherein the total weight of the metal ion and counter ion is at least 99% by weight of the solution excluding the weight of solvent.

In some embodiments, separating the metal ions to obtain at least one essentially pure metal ion solution and/or at least one essentially pure solid metal ion salt comprises one or more of a solid/liquid separation, an extraction, a precipitation, a crystallization, and combinations thereof.

In some embodiments, the method can be performed in part or in whole as a continuous process controlled by sensors and actuators as part of a computer based process control system.

Oxidizing Agents:

In some embodiments, the acidic aqueous solution comprises an oxidizing agent. In some embodiments, an oxidizing agent is an acid such as, for example, H2SO4, HNO3, and combinations thereof. In some embodiments, an oxidizing agent is not an acid such as, for example, O₂, N₂O, and combinations thereof.

In some embodiments, the acidic aqueous solution comprises an acid that is not an oxidizing agent and an oxidizing agent that is not an acid. In some embodiments, the acidic aqueous solution comprises an acid that is an oxidizing agent and an oxidizing agent that is not an acid. In some embodiments, the acidic aqueous solution comprises an acid that is not an oxidizing agent and an oxidizing agent that is an acid. In some embodiments, the acidic aqueous solution comprises an acid that is an oxidizing agent and an oxidizing agent that is an acid. In some embodiments, the acidic aqueous solution comprises an acid that is an oxidizing agent. In some embodiments, an acidic aqueous solution is an oxidizing acidic aqueous solution. In some embodiments, the acidic aqueous solution is not an oxidizing acidic aqueous solution.

EXAMPLES

The following examples are intended to be illustrative and are not meant in any way to limit the scope of the disclosure.

Abbreviations

% percent wt % weight percent ppm parts per million

Li lithium

Ni nickel

Co cobalt

Mn manganese

Cu copper

Al aluminium

Fe iron Black Mass

For the Examples provided below, a black mass was obtained by mechanical comminution of lithium ion batteries and subsequent separation of the black mass as a fine powder from the other constituents of the lithium ion batteries. The black mass was obtained by a process involving a pyrolysis of battery scrap. The material may contain low amounts of sulfur. The metals analyzed are present as oxidic compounds like MnO, CoO, NiO, as salts like LiF, LiO, LiOH, LiAIO₂, U2CO3, and/or as zero oxidation state metals like nickel, cobalt, and copper. The carbon is elemental carbon mainly in the form of graphite with some soot or coke.

Example 1 (comparative)

5 mL of an organic solvent (kerosene) are contacted with 10 mL of an aqueous solution at room temperature. The aqueous solution is a leach solution and stems from an acidic digestion of battery waste material and contains one or more of the elements Li, Ni, Co, Mn, Fe, Cu. Organic and aqueous phases are then vigorously dispersed for 1 min, whereafter a phase separation time was observed. The dispersion remained stable for more than 10 min.

Example 2 (comparative)

50 g of the aqueous solution from Example 1 was filtered off through a PVDF syringe filter with a pore size of 0.45 pm at room temperature. After filtration, 10 mL of an organic solvent (kerosene) are contacted with 20 mL of the filtrate at room temperature. The organic and aqueous phases are then vigorously dispersed for 1 min, whereafter the phase separation time was observed. Complete phase separation occurred only after 10 min.

Example 3

30 g of the aqueous solution from Example 1 was filtered off through a glass frit with a pore size in the range of 1 to 1 .6 pm (corresponding to P1 .6 according to the standard ISO 4793-80) via vacuum filtration and at room temperature. After filtration, 5 mL of an organic solvent (kerosene) are contacted with 10 mL of the filtrate at room temperature. The organic and aqueous phases are then vigorously dispersed for 1 min, whereafter the phase separation time was observed. Complete phase separation occurred within 90 s.

Example 4

50 g of the aqueous solution from Example 1 was filtered off through a fluted filter paper with a pore size of about 20 pm via gravity filtration and at room temperature. The fluted filter paper is a wet strength filter paper with a cellulose content of up to 95 weight percent, wherein each weight percent is by total weight of the filter paper. After filtration, 10 mL of an organic solvent (kerosene) are contacted with 20 mL of the filtrate at room temperature. The organic and aqueous phases are then vigorously dispersed for 1 min, whereafter the phase separation time was observed. Complete phase separation occurred within 120 s.

Comparing Examples 1 and 2 with Example 3, it is recognized that filtering the leach mixture through a glass frit may result in enhanced leaching performance such as, for example, improved phase separation associated with better separation of metal ions.

Comparing Examples 1 and 2 with Example 4, it is recognized that filtering the leach mixture through a fluted filter paper may result in enhanced leaching performance such as, for example, improved phase separation associated with better separation of metal ions. Although the pore size of the fluted filter paper is larger, in this case by a factor of about 50, than the pore size of the PVDF syringe filter, the filtering off is considerably improved due to the surface-active adsorbant of the fluted filter paper. The phase separation time when using the fluted filter paper is only one fifth of the phase separation time when using the PVDF syringe filter. It has been shown that components of the leach mixture containing Si, O and/or C attach to the hydroxyl groups comprised by the surface-active adsorbant of the fluted filter paper. It could be demonstrated that Si was significantly depleted after filtering using the filter means comprising the surface-active adsorbant with hydroxyl groups.

Claims

1. A method for purifying a leach solution of a material, the material comprising one or more metals in a zero oxidation state and one or more chosen from metal oxides, metal hydroxides, metal carbonates and combinations thereof, wherein the method comprises: providing a leach mixture by contacting the material at a temperature ranging from 20°C to 110°C for a total time span ranging from 20 minutes to 10 hours with an acidic aqueous solution having a pH less than 6 and comprising one or more acids, filtering off the leach mixture through a filter means comprising a surface-active adsorbant with hydroxyl groups, to obtain a residue and as a filtrate a purified leach solution in the form of an aqueous solution comprising metal ions wherein emulsifying agents and/or dispersion reagents present in the provided leach mixture are adsorbed by the filter means and thus separated, leaving behind the purified leach solution, wherein the filter means is chosen from a porous glass filter medium and a cellulose containing filter medium.

2. The method according to claim 1 , wherein the porous glass filter medium is a glass frit and the cellulose containing filter medium is a filter paper or a filter cloth.

3. The method according to claim 2, wherein the leach mixture is filtered off through a glass frit via vacuum filtration or through a filter paper via gravity filtration or through a filter cloth via gravity filtration.

4. The method according to claim 2 or 3, wherein the glass frit has a porosity of P40, P16 or P1.6 according to the standard ISO 4793.

5. The method according to claim 2 or 3, wherein the filter paper is a filter paper with a cellulose content in the range of 50 weight percent to 95 weight percent, wherein each weight percent is by total weight of the filter paper, and the filter cloth is a filter cloth with a cellulose content in the range of 50 weight percent to 95 weight percent, wherein each weight percent is by total weight of the filter cloth.

6. The method according to any one of the preceding claims wherein the emulsifying agents and/or dispersion reagents present in the provided leach mixture are from the group comprising Si, C, O, nanoparticles with a particle size < 500nm, gel-like SiOx networks, polysiloxane and derivates, organic residues from a previous pyrolysis of organic binders, and combinations thereof.

7. The method according to any one of the preceding claims wherein the material is a lithium ion battery material comprising one or more chosen from black mass, cathode active material, cathodes, cathode active material precursors, and combinations thereof, and/or wherein the material comprises one or more chosen from lithium, nickel, cobalt, manganese, and combinations thereof.

8. The method according to any one of the preceding claims, wherein the one or more metals in a zero oxidation state is chosen from nickel, cobalt, copper, aluminium, iron, manganese, rare earth metals, and combinations thereof, and/or wherein the metal carbonates are chosen from lithium carbonates, and/or wherein the metal oxides are chosen from nickel oxides, cobalt oxides, copper oxides, aluminium oxide, iron oxides, manganese oxides, rare earth oxides, and combinations thereof, and/or wherein the metal hydroxides are chosen from nickel hydroxides, cobalt hydroxides, copper hydroxides, aluminium hydroxide, iron hydroxides, manganese hydroxides, lithium hydroxides, rare earth hydroxides, alkaline earth hydroxides, and combinations thereof.

9. The method according to any one of the preceding claims, wherein the material or a precursor thereof is pyrolyzed prior to providing the leach mixture.

10. The method according to any one of the preceding claims, wherein the acidic aqueous solution comprises O₂, the O₂ being provided as air, and the air being sparged through the solution at a rate corresponding to up to 20% of the total volume of the solution of O₂ being sparged through the solution per minute.

11. A method comprising: processing a battery material according to any one of claims 1 to 10 to obtain an aqueous solution comprising metal ions, and separating the metal ions to obtain at least one essentially pure metal ion solution and/or at least one essentially pure solid metal ion salt.

12. The method according to claim 11 , wherein separating the metal ions comprises one or more of a solid/liquid separation, an extraction, a precipitation, a crystallization, and combinations thereof.

13. A method comprising: mechanically comminuting at least one battery material chosen from a lithium ion battery, lithium ion battery waste, lithium ion battery production scrap, lithium ion cell production scrap, lithium ion cathode active material, and combinations thereof to obtain a black mass as the material, and subjecting the black mass to the method according to any one of claims 1 to 10, optionally further comprising subjecting the black mass to a heat treatment step prior to subjecting the black mass to the method according to any one of claims 1 to 10.