Method for the elution of aluminum ions and / or zinc ions

Abstract

The present invention relates to a method for the elution of aluminum ions and / or zinc ions of polymers containing aminomethylphosphonic acid groups.

Description

[0001] Process for the elution of aluminum and / or zinc ions

[0002] The present invention relates to a process for the elution of aluminum and / or zinc ions from polymers containing aminomethylphosphonic acid groups.

[0003] The recycling of lithium-ion batteries is a critical technology for enabling the transition to more sustainable electromobility. Ion exchange resins represent a promising technology for removing contaminants such as copper, aluminum, and zinc from electrolyte concentrates resulting from recycled lithium-ion batteries. The use of polymers containing phosphonate groups is known, for example, from WO-A 2012 / 113657 as being particularly suitable for removing divalent and trivalent metal ions. WO-A 2012 / 113657 also discloses that the polymers containing phosphonate groups can be regenerated using an alkaline solution containing tartrate, citrate, oxalate, or EDTA ions, thereby removing the metal ions from the polymer.

[0004] Virolainen et al. (S. Virolainen, T. Vesselborg, A. Kaukinen, T. Sainio, Hydrometallurgy 2021, 202, 105602, pp. 1 to 9) describe that polymers containing aminomethylphosphonic acid groups, such as Lewatit® MDS TP 260, are particularly suitable for removing aluminum and iron from a mixture of aluminum, copper, manganese, iron, lithium, nickel, and cobalt concentrates. For this purpose, Virolainen et al. developed a two-step process in which the metal ions are first bound to the polymer containing aminomethylphosphonic acid groups. Then, in a first step, copper, manganese, and cobalt are eluted with sulfuric acid. The cobalt solution is reabsorbed, and in a second step, the aluminum is complexed with an alkaline potassium oxalate solution and eluted.

[0005] State-of-the-art elution processes for aluminum and / or zinc ions on polymers containing aminomethylphosphonic acid groups involve the use of complexing agents, as the binding affinity of aluminum and zinc ions to the phosphonic acid groups is very high. However, complexing agents are compounds that pollute wastewater, thus presenting ecological disadvantages and therefore having to be removed. This, in turn, increases the costs of the process.

[0006] Therefore, there continued to be a need for a process with which aluminum and / or zinc ions can be eluted with high selectivity from polymers containing aminomethylphosphonic acid groups. It has now been surprisingly found that the elution of aluminum and / or zinc ions from polymers containing aminomethylphosphonic acid groups can be achieved with high selectivity if a base selected from the group consisting of alkali metal hydroxides and ammonium hydroxide, or mixtures of these bases, is used for elution.

[0007] The present invention therefore relates to a process for the elution of aluminum and / or zinc ions, in which a polymer containing aminomethylphosphonic acid groups or salts thereof which are at least partially loaded with aluminum and / or zinc ions is mixed with a base selected from the group consisting of alkali metal hydroxides and ammonium hydroxide or mixtures of these bases and the aluminum and / or zinc ions are eluted.

[0008] The scope of the invention includes all the radical definitions, parameters and explanations listed above and below, whether general or in preferred ranges, among each other, and therefore also between the respective ranges and preferred ranges in any combination.

[0009] Polymers containing aminomethylphosphonic acid groups are preferably polystyrene copolymers containing aminomethylphosphonic acid groups. Even more preferably, polymers containing aminomethylphosphonic acid groups are polystyrene-divinylbenzene copolymers containing aminomethylphosphonic acid groups.

[0010] Polymers containing aminomethylphosphonic acid groups include polymers containing aminomethylmonophosphonic acid groups, polymers containing aminomethyldiphosphonic acid groups, and their salts. Salts of the polymers containing aminomethylphosphonic acid groups are preferably alkali metal salts, alkaline earth metal salts, and metal salts of groups III to XII of the Periodic Table of the Elements. Salts of the polymers containing aminomethylphosphonic acid groups are preferably sodium, potassium, lithium, magnesium, calcium, iron, copper, manganese, cobalt, and nickel salts. Salts of polymers containing aminomethylphosphonic acid groups can particularly preferably be their sodium, potassium, lithium, cobalt, and nickel salts. Sodium, potassium, or nickel salts are particularly preferably used as salts of the polymers containing aminomethylphosphonic acid groups.

[0011] As polystyrene copolymers, copolymers of monovinylaromatic monomers selected from the group consisting of styrene, vinyltoluene, ethylstyrene, a-methylstyrene, chlorostyrene or chloromethylstyrene and mixtures of these monomers with polyvinylaromatic compounds (crosslinkers) selected from the group consisting of divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene and / or trivinylnaphthalene are preferably used.

[0012] A styrene / divinylbenzene copolymer is particularly preferably used as the polystyrene copolymer backbone. A styrene / divinylbenzene copolymer is a copolymer crosslinked by the use of divinylbenzene. Technical-grade divinylbenzene is preferably used, which can contain up to 30 wt.% ethylvinylbenzene. Therefore, the styrene / divinylbenzene copolymer also includes copolymers that additionally contain ethylvinylbenzene as a monomer.

[0013] The polymer preferably has a spherical shape.

[0014] The polymers containing aminomethylphosphonic acid groups preferably have a macroporous structure.

[0015] The terms "microporous," "gel-like," or "macroporous" have already been described in detail in the specialist literature, for example, in Seidl, Malinsky, Dusek, Heitz, Adv. Polymer Sei., 1967, Vol. 5, pp. 113 to 213. Possible measurement methods for macroporosity, such as mercury porosimetry and BET determination, are also described there. Generally, and preferably, the pores of macroporous polymers containing aminomethylphosphonic acid groups have a diameter of 20 nm to 100 nm.

[0016] The polymers containing aminomethylphosphonic acid groups preferably have a monodisperse distribution.

[0017] In the present application, substances are referred to as monodisperse if at least 90% by volume or mass of the particles have a diameter which lies in the interval with a width of + / - 10% of the most common diameter around the most common diameter.

[0018] For example, for a substance with a most common diameter of 0.5 mm, at least 90 volume or mass% lies in a size interval between 0.45 mm and 0.55 mm, for a substance with a most common diameter of 0.7 mm, at least 90 volume or mass% lies in a size interval between 0.77 mm and 0.63 mm.

[0019] The polymer containing aminomethylphosphonic acid groups preferably has a diameter (d5o) of 200 to 1500 pm.

[0020] It most preferably has a diameter (d50) of 250 pm to 450 pm. Polymers containing aminomethylphosphonic acid groups can be prepared by known processes, e.g., by phthalamidomethylation of a styrene-divinylbenzene copolymer and functionalization of the resulting amino groups by reacting PH acidic compounds in sulfuric acid suspension with formalin. They are also commercially available, e.g., as Lewatit® MDS TP 260 from LANXESS Deutschland GmbH.

[0021] The average degree of substitution indicates the statistical ratio between unsubstituted, monosubstituted, and disubstituted aminomethyl groups in the polymer containing aminomethylphosphonic acid groups. The average degree of substitution can therefore range between 0 and 2. With a degree of substitution of 0, no substitution would have occurred, and the aminomethyl groups would be present as primary amine groups. With a degree of substitution of 2, all aminomethyl groups in the resin would be disubstituted by phosphonic acid groups. With a degree of substitution of 1, statistically speaking, all aminomethyl groups in the resin would be monosubstituted.

[0022] The average degree of substitution of the aminomethyl groups by phosphonic acid groups in the polymer containing aminomethylphosphonic acid groups is preferably 1.4 to 2.0.

[0023] The aminomethylphosphonic acid group-containing polymers preferably have a total hydrogen capacity of 2.5 mol / L to 7.0 mol / L resin. The aminomethylphosphonic acid group-containing polymers most preferably have a total hydrogen capacity of 3.0 to 3.4 mol / L resin.

[0024] The determination of the total capacity of polymers containing aminomethylphosphonic acid groups is carried out according to DIN 54403 (Testing of ion exchangers - Determination of the total capacity of cation exchangers).

[0025] As polymer containing aminomethylphosphonic acid groups, chelate resins containing functional groups of the structural element (I) are preferably used. wherein represents the polystyrene copolymer backbone and R 1 and R 2 can be the same or different and independently represent - CH2PO(OX 1 )2and -CH2PO(OH)OX 2 or hydrogen, where R 1 and R 2both cannot be hydrogen at the same time and X 1 and X 2 independently represent hydrogen, sodium, potassium or lithium.

[0026] Preferably, R 1 and R 2 independently of each other -CH2PO(OX 1 )2and - CH2PO(OH)OX 2 Preferably, X 1 and X 2 = H.

[0027] In the polystyrene copolymer backbone, the -CH2-NR 1 R 2 -group attached to a phenyl residue.

[0028] Preferably, polymers containing aminomethylphosphonic acid groups are macroporous, monodisperse chelate resins containing functional groups of the structural element (I).

[0029] The polymers containing aminomethylphosphonic acid groups can be partially or completely loaded with aluminum and / or zinc ions.

[0030] Preferably, the polymer containing aminomethylphosphonic acid groups is loaded with 10 mol% to 90 mol% of aluminum and / or zinc ions, based on the total capacity of the polymer.

[0031] Sodium hydroxide and potassium hydroxide are preferred as alkali metal hydroxides. The alkali metal hydroxides are preferably present in an aqueous solution.

[0032] The alkali metal hydroxide solution preferably contains between 5 wt.% and 20 wt.% alkali metal hydroxides. More preferably, the alkali metal hydroxide solution contains 6 wt.% to 12 wt.% alkali metal hydroxide.

[0033] In a further preferred embodiment, the alkali metal hydroxide solution contains 5 wt.% to 20 wt.% alkali metal hydroxide and 79 wt.% to 94 wt.% water, and up to 1 wt.% organic solvents or other impurities, such as alkaline earth metal hydroxides or potassium oxalate. If potassium oxalate is present, the proportion is in any case < 0.1 wt.%.

[0034] In a further preferred embodiment, the alkali metal hydroxide solution contains 6 wt.% to 12 wt.% alkali metal hydroxide and 87 wt.% to 93 wt.% water, with up to 1 wt.% organic solvents or other impurities, such as alkaline earth metal hydroxides or potassium oxalate, possibly present. If potassium oxalate is present, the proportion is in any case < 0.1 wt.%. In a further preferred embodiment, the alkali metal hydroxide solution consists of 5 wt.% to 20 wt.% alkali metal hydroxide and 80 wt.% to 95 wt.% water, and the sum of these compounds amounts to 100 wt.%.

[0035] As ammonium hydroxide, solutions of ammonia in water in a concentration between 15 wt.% and 35 wt.% are preferably used.

[0036] In a further preferred embodiment, the ammonium hydroxide solution contains 15 wt.% to 35 wt.% alkali metal hydroxide and 84 wt.% to 64 wt.% water, with up to 1 wt.% organic solvents or other impurities, such as alkaline earth metal hydroxides or potassium oxalate, possibly present. If potassium oxalate is present, the proportion is in any case < 0.1 wt.%.

[0037] In a further preferred embodiment, the bases used do not contain any complexing agents. Complexing agents within the meaning of the invention are preferably solutions containing tartrate, citrate, oxalate, or EDTA ions. Even more preferably, the base does not contain any oxalate ion, in particular no potassium oxalate.

[0038] Elution can be performed in batch mode or by column application. The amount of base to be applied for elution is preferably 1 to 10 bed volumes of polymer, particularly preferably 3 to 7 bed volumes of polymer.

[0039] During elution, the pH of the eluate is preferably 10 to 14.

[0040] Preferably, the elution takes place at temperatures of 60 °C to 90 °C. To achieve this temperature, the base can be heated or the polymer containing aminomethylphosphonic acid groups can be heated in the column process, for example and preferably, by a heating coil.

[0041] After elution, the polymer containing aminomethylphosphonic acid groups can be regenerated by contacting it with an acid. This step not only removes impurities but also recharges the polymer containing aminomethylphosphonic acid groups to the H form. This allows the resin to be recharged with metal ions. Inorganic acids are preferably used as acids for regenerating the polymer containing aminomethylphosphonic acid groups. Sulfuric acid, hydrochloric acid, and nitric acid are preferred inorganic acids. Sulfuric acid is particularly preferred for regenerating the polymer containing aminomethylphosphonic acid groups. Sulfuric acid is preferably used in a concentration of 5% - 20% by weight for regenerating the polymer containing aminomethylphosphonic acid groups.

[0042] In a further preferred embodiment, the invention comprises a process for the elution of aluminum and / or zinc ions, in which at least one chelate resin containing functional groups of the structural element (I) wherein stands for the polystyrene copolymer backbone and

[0043] R 1 and R 2 can be the same or different and independently represent - CH2PO(OX 1 )2and -CH2PO(OH)OX 2 or hydrogen, where R 1 and R 2 both cannot be hydrogen at the same time and X 1 and X 2independently of one another stand for hydrogen, sodium, potassium and lithium, in a step a.) is brought into contact with the chelate resin with an aqueous metal ion solution containing aluminum and / or zinc ions and optionally further metal ions, and in a step b.) the aluminum and / or zinc ions are eluted with an aqueous alkali metal hydroxide solution or ammonium hydroxide solution or mixtures of these bases.

[0044] Step a.)

[0045] The metal and / or aluminum and / or zinc ions are brought into contact with the chelating resin containing functional groups of the structural element (I) in an aqueous metal ion solution. Metal adsorption can be carried out in a batch process or by application to a column. Adsorption is preferably carried out in a column process.

[0046] In step a.), aluminum and / or zinc ions can be used in a concentration of 10 pg / L to 5 g / L. Preference is given to using aluminum and / or zinc ions in a concentration of 1 mg / L to 1 g / L. The chelate resin containing functional groups of the structural element (I) can be brought into contact with and loaded with other metal ions. The metal ions used can preferably be the ions of the metals iron, copper, manganese, cobalt, nickel and lithium. Preference is given to using divalent or trivalent iron ions. Preference is given to using divalent copper, manganese, cobalt and / or nickel ions. Preference is given to using trivalent aluminum ions. Preference is given to using divalent zinc ions. Particular preference is given to using lithium, nickel and cobalt ions. Even more preference is given to using nickel and cobalt ions.

[0047] Preferably, an aqueous metal ion solution of aluminum ions, nickel ions and cobalt ions is applied to the chelate resin in step a.).

[0048] Preferably, the molar ratio of the aluminum ions to the nickel ions and / or the cobalt ions in step a.) is 0.5 to 1.5.

[0049] The ratio of the weight concentration of the metal ions to the aluminum and / or zinc ions in step a.) in the chelate resin is preferably 100:1 to 2:1.

[0050] The ratio of the weight concentration of the lithium ions to the aluminum and / or zinc ions in step a.) in the chelate resin is preferably 100:1 to 2:1.

[0051] The ratio of the weight concentration of the cobalt ions to the aluminum and / or zinc ions in step a.) in the chelate resin is preferably 100:1 to 2:1.

[0052] The ratio of the weight concentration of the manganese ions to the aluminum and / or zinc ions in step a.) in the chelating resin is preferably 100:1 to 2:1.

[0053] The ratio of the weight concentration of the copper ions to the aluminum and / or zinc ions in step a.) in the chelate resin is preferably 100:1 to 2:1.

[0054] The ratio of the weight concentration of the iron ions to the aluminum and / or zinc ions in step a.) in the chelate resin is preferably 100:1 to 2:1.

[0055] The ratio of the weight concentration of the nickel ions to the aluminum and / or zinc ions in step a.) in the chelating resin is preferably 100:1 to 2:1.

[0056] An inorganic metal salt solution is preferably used as the aqueous metal ion solution in step a.). Nitrates, chlorides, or sulfates are particularly preferably used as inorganic metal salts. Metal sulfates are very particularly preferred. Cobalt(II) sulfate, nickel(II) sulfate, and aluminum(III) sulfate are preferably used. In a further preferred embodiment, in step a.), the chelate resin containing functional groups of the structural element (I) is loaded with aluminum ions, which may contain further metal ions, but no zinc ions are present.

[0057] Preferably, in step a.) chelate resins containing functional groups of the structural element (I) with a specific flow rate of 2 to 10 bed volumes per hour (BV / h) are used.

[0058] Preferably, in step a.) 0.5 to 1.5 equivalents (Eq) of chelate resins containing functional groups of the structural element (I) are used per equivalent (Eq) of aluminum and / or zinc ions.

[0059] The loading of the chelate resins containing functional groups of structural element (I) with metal ions in step a.) preferably takes place at a pH of 1.5 to 6.0. Since the metal ions used are Lewis acids, this pH is often already present in the aqueous solution used. If the pH is not present, the pH can be adjusted using an acid, preferably an inorganic acid. Sulfuric acid, hydrochloric acid, or nitric acid is preferably used for this purpose. Sulfuric acid is particularly preferred.

[0060] Step b.)

[0061] In step b.), the aluminum and / or zinc ions are eluted from the chelate resin containing functional groups of structural element (I). Trivalent aluminum ions are preferably used in step a.) and eluted in step b.). Divalent zinc ions are preferably used in step a.) and eluted in step b.). Elution is preferably carried out using an alkali metal hydroxide solution. Aluminum ions are preferably eluted in step b.).

[0062] By means of the process according to the invention, in which alkali metal and / or ammonium hydroxide solutions are used for the selective separation of aluminum and / or zinc ions from polymers containing aminomethylphosphonic acid groups and / or chelate resins containing functional groups of the structural element (I), a possibility has been created for the selective processing of metal-containing lithium waste from used batteries. Methods

[0063] ICP

[0064] The ion concentration can be determined using methods known to those skilled in the art. The ion concentration is preferably determined in the method according to the invention using an inductively coupled plasma spectrometer (ICP).

[0065] The effluent from the ion exchange column was fractionated into 10 ml fractions and analyzed by ICP, and the ion concentration was determined.

[0066] Determination of total capacity

[0067] The determination of the total capacity of chelate resins containing functional groups of the structural element (I) is carried out according to DIN 54403 (Testing of ion exchangers - Determination of the total capacity of cation exchangers).

[0068] Determination of the diameter of the polymers

[0069] The diameter of the polymers is determined according to DIN 54407: Testing of ion exchangers: Determination of particle size distribution. The diameter d50 is the diameter of the polymers or polymer particles at which 50% of the polymers pass through a sieve with a mesh size of 0.5 mm and 50% remain.

[0070]

[0071] A. Loading of a macroporous, monodisperse chelate resin containing functional groups of the structural element (I) with aluminum, nickel and cobalt

[0072] 200 ml of the chelate resins containing functional groups of the structural element (I) with R 1 and R 2 independently for -CH2PO(OX 1 )2 and -CH2PO(OH)OX 2 where X 1 and X 2= H, (Lewatit® MDS TP 260, degree of substitution of the aminomethyl groups by phosphonic acid groups = 2.0, total capacity 3.2 mol / L H-form, dso 0.385 mm, monodisperse and macroporous), in the H-form are dispersed in deionized water and adjusted to pH = 4 in a beaker while stirring with H2SO4. Then, 250 ml of an aqueous Co 2+ / Ni 2+ / Al 3+Sulfate solution containing 6.95g (0.118 mol / 0.027 g / L) cobalt, 6.93g (0.118 mol) nickel, and 3.20g (0.118 mol) aluminum was added while stirring. The pH value in the supernatant of the ion exchanger fell from 4.0 to 1.9 during the addition of the solution. The supernatant solution was then completely decanted and quantified by liter. The chelate resin was washed several times with deionized water and filtered with suction to remove adhering Co, Ni, and Al (850 ml wash water). The loading capacity of the chelate resin containing functional groups of structural element (I) was calculated by the decrease in Al, Ni, and Co in the supernatant and is: Al1 10.9 g / L (0.4 mol / L), Ni 0.8 g / L (0.0135 mol / L), and Co 1.1 g / L (0.0135 mol / L). 37.8% of the total capacity of the resin was loaded with aluminum ions.

[0073] B. Selective aluminum elution with NaOH and regeneration by dilute sulfuric acid

[0074] In the next step, 20 ml of chelate resin containing functional groups of structural element (I) from A are eluted with 100 ml of 9 wt.% aqueous NaOH over 3 hours at 80°C with stirring. The alkaline solution is then decanted. A portion of the completely regenerated resin is then dried and digested in a microwave. The aluminum, nickel, and cobalt concentrations are determined using ICP (inductively coupled plasma spectrometry). The aluminum concentration is below the detection limit. The nickel and cobalt concentrations on the chelate resin containing functional groups of structural element (I) remain unchanged within the detection limits. The remaining chelate resin is thoroughly washed and regenerated with 100 ml of 15 wt.% H2SO4 at room temperature with stirring over 1 hour. After a washing step with 80 ml of deionized water, the excess NaOH is removed.The nickel and cobalt remaining on the ion exchanger were eluted within the detection limits at almost 100 wt.% by the addition of 15 wt.% H2SO4.

Claims

1. A method for elution of aluminium and / or zinc ions, characterized in that an aminomethylphosphonic acid group-containing polymer or its salts, at least partially loaded with aluminium and / or zinc ions, is treated with a base selected from the group consisting of alkali metal hydroxides and ammonium hydroxide and mixtures of these bases, and the aluminium and / or zinc ions are eluted.

2. Method according to claim 1, characterized in that aminomethylphosphonic group-containing polystyrene-divinylbenzene copolymers are used as polymers containing aminomethylphosphonic groups.

3. Method according to claim 1 or 2, characterized in that the average degree of substitution of the aminomethyl groups by phosphonic acid groups in the aminomethylphosphonic acid group-containing polymer is 1.4 to 2.

0.

4. Method according to at least one of claims 1 to 3, characterized in that the base does not contain potassium oxalate.

5. Method according to at least one of claims 1 to 4, characterized in that the polymers have a diameter (d5o) of 250 pm to 450 pm.

6. Method according to claim 5, characterized in that at least 90 volume or mass % of the particles have a diameter which lies within the interval with a width of + / - 10 % of the most frequent diameter around the most frequent diameter.

7. Method according to at least one of claims 1 to 6, characterized in that an aqueous 6 wt % - 12 wt % alkali metal hydroxide solution is used.

8. Method according to at least one of claims 1 to 7, characterized in that the elution of aluminium ions is involved.

9. Method according to at least one of claims 1 to 8, characterized in that the polymer containing aminomethylphosphonic acid groups includes chelating resins containing functional groups of the structural element (I) wherein for the polystyrene copolymer framework and R 1 and R 2 can be the same or different and independent of each other for - CH2PO(OX 1 )2 and -CH2PO(OH)OX 2 or hydrogen, where R 1 and R 2 They cannot both be hydrogen at the same time, and X 1 and X 2 can be used independently of one another for hydrogen, sodium, potassium or lithium. A process for the elution of aluminum and / or zinc ions, characterized in that at least one chelating resin contains functional groups of the structural element (I) wherein for the polystyrene copolymer framework and where R1 and R 2 , X 1 and X 2 the above-mentioned meaning, in one step a.) the chelating resin is brought into contact with an aqueous metal ion solution containing aluminum and / or zinc ions and optionally other metal ions, and in one step b.) the aluminum and / or zinc ions are eluted with an aqueous alkali metal hydroxide solution and / or ammonium hydroxide solution. The method according to claim 10, characterized in that R 1 and R 2 can be the same or different and independent of each other for -CH2PO(OX 1 )2 and - CH2PO(OH)OX 2 The method according to claim 11, characterized in that X 1 and X 2 = H are. A method according to at least one of claims 10 to 12, characterized in that an aqueous metal ion solution consisting of aluminum ions, nickel ions, and cobalt ions is applied to the chelating resin in step a). A method according to claim 13, characterized in that the molar ratio of aluminum ions to the nickel ions and / or the cobalt ions in Step a.) is 0.5 to 1.

5. A method according to at least one of claims 10 to 14, characterized in that the aqueous metal ion solution containing aluminium ions, nickel ions and cobalt ions, which is applied to the chelating resin in step a.), has a pH value of 1.5 to 6.0.

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