Nickel recovery method

Abstract

Provided is a nickel recovery method for efficiently recovering nickel from a nickel solution containing 2,2'- bipyridine and a nickel compound generated in an organic chemical reaction process.　The nickel recovery method according to the present invention comprises: (a) a step for preparing a nickel solution containing 2,2'- bipyridine and a nickel compound generated in an organic chemical reaction process; (b) a step for adding an alkali metal perchlorate to the nickel solution to form a tris (2,2'- bipyridine) perchlorate nickel salt serving as an ion pair; and (c) a step for recovering the tris (2,2'- bipyridine) perchlorate nickel salt.

Description

Nickel recovery methods

[0001] The present invention relates to a method for recovering nickel from a nickel solution produced in an organic chemical reaction process.

[0002] Non-patent document 1 describes a method for producing organic compounds, characterized by the use of a nickel compound as a catalyst.

[0003] Patent Document 1 provides a step of preparing a monomer for forming a hydrophobic group, comprising (A) a single aromatic ring, or a divalent hydrocarbon group, a divalent silicon-containing group, a divalent nitrogen-containing group, a divalent phosphorus-containing group, a divalent oxygen-containing group, a divalent sulfur-containing group, or multiple aromatic rings bonded to each other via direct bonding, wherein two halogen atoms, pseudohalides, or boronic acid groups are bonded to the aromatic rings, and (B) a monomer for forming a hydrophobic group, comprising a single aromatic ring, or a divalent hydrocarbon group, a divalent silicon-containing group, a divalent nitrogen-containing group, a divalent phosphorus-containing group The process of preparing a monomer for forming a hydrophilic group, comprising: (C) bis(1,5-cyclooctadiene)nickel(0) and a polymerization accelerator; and a plurality of aromatic rings bonded to each other via a linking group which is a grouped, divalent oxygen-containing group, or divalent sulfur-containing group, and / or direct bonds, wherein two halogen atoms, pseudohalides, or boronic acid groups are bonded to the aromatic rings, and at least one of the linking group or aromatic rings is bonded to a divalent saturated hydrocarbon group or an anion exchange precursor functional group via direct bonds; and (C) bis(1,5-cyclooctadiene)nickel(0) and a polymerization accelerator. A method for producing an anion exchange resin, comprising the steps of (D) reacting a hydrogen peroxide group-forming monomer with a hydrophilic group-forming monomer in the presence of 2,2'-bipyridine as a ligand to synthesize a polymer, and (C) ionizing the anion exchange precursor functional group to form an anion exchange group, wherein the number of moles of bis(1,5-cyclooctadiene)nickel(0) used in step (C) is 1.2 to 1.8 times the total number of moles of the hydrogen peroxide group-forming monomer and the hydrophilic group-forming monomer. The present invention describes a method for producing an anion exchange resin, characterized in that the number of moles of 2,2'-bipyridine used in step (C) is 1.5 to 2.5 times the number of moles of bis(1,5-cyclooctadiene)nickel(0), and in the anion exchange resin, the residues of the monomer for forming the hydrophobic group form a divalent hydrophobic group, the residues of the monomer for forming the hydrophilic group having the anion exchange group form a divalent hydrophilic group, and the hydrophobic group and the hydrophilic group are bonded together via a direct bond.

[0004] Patent Document 2 describes a process for preparing a monomer for forming a hydrophobic group, comprising (A) a single aromatic ring, or a divalent hydrocarbon group, a divalent silicon-containing group, a divalent nitrogen-containing group, a divalent phosphorus-containing group, a divalent oxygen-containing group, a divalent sulfur-containing group, or multiple aromatic rings bonded to each other via direct bonding, with two chlorine atoms bonded to the aromatic rings, and (B) a monomer for forming a hydrophobic group, comprising a single aromatic ring, or a divalent hydrocarbon group, a divalent silicon-containing group, a divalent nitrogen-containing group, a divalent (C) Bis(1,5-cyclooctadiene)nickel as a catalyst A method for producing an anion exchange resin is described, comprising the steps of (0) reacting a hydrogen peroxide-forming monomer with a hydrophilic group-forming monomer in the presence of a co-ligand (0), 2,2'-bipyridine, a bromide or iodide as a co-catalyst, and a reducing agent to synthesize a polymer, and (D) ionizing the anion exchange precursor functional group to form an anion exchange group, wherein the number of moles of bis(1,5-cyclooctadiene)nickel (0) used in step (C) is 0.3 to 1.8 times the total number of moles of the hydrogen peroxide-forming monomer and the hydrophilic group-forming monomer, and in the anion exchange resin, residues of the hydrogen peroxide-forming monomer form a divalent hydrogen peroxide group, residues of the hydrophilic group-forming monomer having an anion exchange group form a divalent hydrophilic group, and the hydrogen peroxide group and the hydrophilic group are bonded via a direct bond.

[0005] Patent Document 3 describes a method for recovering nickel, comprising the steps of (a) preparing a nickel solution containing a nickel compound produced in an organic chemical reaction process, (b) adjusting the pH of the nickel solution to 3 or higher, and (c) adding an alkali metal sulfide to the nickel solution whose pH has been adjusted to 3 or higher to obtain a nickel sulfide precipitate.

[0006] Nature 2014, 509, 299-309. Japanese Patent Publication No. 2022-18683, Japanese Patent Publication No. 2022-24326, Japanese Patent Publication No. 2023-123944

[0007] In the manufacturing methods described in Non-Patent Document 1 and Patent Documents 1-2, the nickel compounds used as catalysts or polymerization accelerators are not incorporated into the product, and therefore all the nickel used in the reaction is contained in the wastewater. There is a need to recover the nickel in the wastewater generated in such organic chemical reaction processes and reuse it as a new resource. While such nickel can be efficiently recovered using the method described in Patent Document 3, there were limitations to increasing the nickel recovery rate when the wastewater contained not only nickel but also 2,2'-bipyridine.

[0008] Therefore, the present invention aims to provide a method for efficiently recovering nickel from a nickel solution containing a nickel compound produced in an organic chemical reaction process and 2,2'-bipyridine.

[0009] To solve the aforementioned problems, the present invention provides a nickel recovery method comprising: (a) preparing a nickel solution containing a nickel compound produced in an organic chemical reaction process and 2,2'-bipyridine; (b) adding an alkali metal perchlorate salt to the nickel solution to form a tris(2,2'-bipyridine)nickel perchlorate salt that forms an ion pair; and (c) recovering the tris(2,2'-bipyridine)nickel perchlorate salt.

[0010] The nickel recovery method of the present invention is suitable in the following cases: - The nickel compound is a nickel halide. - The alkali metal perchlorate salt is potassium perchlorate or sodium perchlorate. - In step (c), a recovery solvent that separates from the nickel solution is added to move the tris(2,2'-bipyridine)nickel perchlorate to the recovery solvent phase, and after separating the recovery solvent phase, the recovery solvent is removed. - In step (c), the precipitated tris(2,2'-bipyridine)nickel perchlorate is separated. - Between step (a) and step (b), the method includes (d) a step of adjusting the pH of the nickel solution to 8 or higher to precipitate nickel hydroxide, and (e) a step of recovering the nickel hydroxide. - In step (d), sodium hydroxide is added to the nickel solution. - Between step (a) and step (b), the process includes (f) adjusting the pH of the nickel solution to 3 or higher, (g) adding an alkali metal sulfide to the nickel solution whose pH has been adjusted to 3 or higher to precipitate nickel sulfide, and (h) recovering the nickel sulfide. - In step (f), sodium hydroxide is added to the nickel solution. - The alkali metal sulfide is sodium sulfide. - The organic chemical reaction process is a process for producing an organic polymer compound. - The organic polymer compound is an ion exchange resin. - The ion exchange resin is an anion exchange resin.

[0011] According to the present invention, nickel can be efficiently recovered from a nickel solution containing a nickel compound produced in an organic chemical reaction process and 2,2'-bipyridine.

[0012] This invention provides an efficient method for recovering nickel from nickel solutions containing nickel compounds produced in organic chemical reaction processes. More specifically, it involves recovering nickel (Ni), which is widely used as a catalyst in organic chemical reaction processes, from wastewater after the process is completed. This makes it possible to recover nickel that was previously treated as wastewater and reuse it as a new resource.

[0013] In the present invention, first, a nickel solution containing a nickel compound produced by an organic chemical reaction process and 2,2'-bipyridine is prepared (step (a)). The organic chemical reaction process can be a process for producing organic low molecular weight compounds and / or organic polymer compounds, but is suitable for a process for producing organic polymer compounds. Examples of organic polymer compounds include ion exchange resins, superabsorbent polymers, conductive polymers, piezoelectric polymers, self-healing polymers, general-purpose plastics, and engineering plastics. Among these, ion exchange resins are preferred, and anion exchange resins are more preferred. An example of a process for producing anion exchange resins is a polymer production process by cross-coupling using bis(1,5-cyclooctadiene)nickel(0) as a polymerization accelerator (catalyst) and 2,2'-bipyridine as a coligand, as described in Patent Documents 1 to 2.

[0014] Nickel compounds produced in organic chemical reaction processes include nickel halides such as nickel fluoride, nickel chloride, nickel bromide, and nickel iodide; and inorganic nickel acids such as nickel nitrate and nickel sulfate. For example, the nickel compound produced in the polymer manufacturing process described in the examples of Patent Documents 1 and 2 is nickel chloride.

[0015] Nickel ions (Ni) contained in nickel solution ２＋ Regarding the ratio of ) to 2,2'-bipyridine (bpy), the more 2,2'-bipyridine there is, the more complex (especially [Ni(bpy) described later) ３ ] ２＋ ) is formed, therefore nickel ions (Ni ２＋ The molar ratio of 2,2'-bipyridine to ) (bpy / Ni ２＋ ) is preferably 1 to 3, and more preferably 2 to 3.

[0016] Nickel solutions containing the above-mentioned nickel compounds are produced in an organic chemical reaction process and therefore typically contain organic solvents. Examples of organic solvents include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol (2-methyl-1-propanol), and tert-butyl alcohol (2-methyl-2-propanol); ethers such as diethyl ether and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; aliphatic hydrocarbons such as n-pentane, n-hexane, and n-heptane; aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; nitrogen-containing organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; sulfur-containing organic solvents such as dimethyl sulfoxide, dimethyl sulfone, and sulfolane; and nitrobenzene. For example, the nickel solutions containing nickel compounds produced in the polymer manufacturing process described in the examples of Patent Documents 1 and 2 contain water and methanol, an organic solvent, as solvents.

[0017] The solvent in the nickel solution may be water, an organic solvent, or a mixed solvent of water and an organic solvent. When the solvent in the nickel solution is a mixed solvent of water and an organic solvent, the content of the organic solvent in the mixture is, for example, 0.1 vol% or more, preferably 50 vol% or more.

[0018] Here, if 2,2'-bipyridine is present in the nickel solution as well as nickel compounds, nickel ions (Ni ２＋ ) reacts with 2,2'-bipyridine (bpy) to form a complex as follows.

[0019]

[0020] These complexes (especially [Ni(bpy)]) ３ ] ２＋)(0) forms a complex very stably in a nickel solution, and nickel sulfide does not precipitate even when an alkali metal sulfide is added to the nickel solution as in the method described in Patent Document 3. Therefore, there was a limit to increasing the recovery rate of nickel.

[0021] Therefore, in the present invention, an alkali metal perchlorate is added to the nickel solution (step (b)). By doing so, tris(2,2'-bipyridine)nickel perchlorate, which forms an ion pair, is formed in the nickel solution. Examples of the alkali metal perchlorate include lithium perchlorate, sodium perchlorate, and potassium perchlorate. From the viewpoint of solubility, potassium perchlorate or sodium perchlorate is preferable, and sodium perchlorate is more preferable.

[0022] In the present invention, next, tris(2,2'-bipyridine)nickel perchlorate is recovered (step (c)). When a recovery solvent (organic solvent) that is immiscible with the nickel solution is added, the formed tris(2,2'-bipyridine)nickel perchlorate moves to the recovery solvent phase (organic solvent phase). Therefore, tris(2,2'-bipyridine)nickel perchlorate can be recovered by separating the recovery solvent phase and then removing the recovery solvent. The recovery solvent (organic solvent) removed here can be reused as the recovery solvent. Examples of the recovery organic solvent include halogenated hydrocarbons such as 1,2-dichloroethane, chloroform, and dichloromethane; and nitrobenzene. When the amount of tris(2,2'-bipyridine)nickel perchlorate produced is large, tris(2,2'-bipyridine)nickel perchlorate precipitates, and thus it can be easily recovered by separation by filtration or the like.

[0023] In the present invention, in addition to the above steps, it is preferable to have a step of recovering nickel as nickel hydroxide (hydroxide method). By recovering nickel by the hydroxide method in advance, the molar ratio of 2,2'-bipyridine (bpy) to nickel ions (Ni ２＋ )(bpy / Ni ２＋ ) in the nickel solution can be increased, and the recovery rate of nickel can be increased.

[0024] In the hydroxide method, first, between steps (a) and (b), the pH of the nickel solution is adjusted to 8 or higher (step (d)). That is, if the pH of the nickel solution prepared in step (a) is less than 8, an alkaline component should be added so that the pH becomes 8 or higher. Examples of alkaline components to be added here include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; and carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, magnesium carbonate, and calcium carbonate. Among these, alkali metal hydroxides are preferred, and sodium hydroxide is more preferred. It should be noted that the use of alkali metal sulfides as the alkaline component here is undesirable. In this way, nickel ions and hydroxide ions in the nickel solution react to form nickel hydroxide (Ni(OH)), which has an extremely small solubility product. ２ Since ) precipitates, nickel can be recovered efficiently.

[0025] When the hydroxide method is used in combination, the nickel hydroxide obtained above is then recovered (step (e)). Since the nickel hydroxide precipitated in the nickel solution has an extremely small solubility product, it can be easily recovered by filtration or the like.

[0026] In the present invention, it is preferable to have a step of recovering nickel as nickel sulfide (sulfide method) in addition to the above step. By recovering nickel in advance using the sulfide method, nickel ions (Ni) contained in the nickel solution can be recovered. ２＋ ) and the molar ratio of 2,2'-bipyridine (bpy) (bpy / Ni ２＋ This can increase the recovery rate of nickel.

[0027] In the sulfide process, first, between steps (a) and (b), the pH of the nickel solution is adjusted to 3 or higher (step (f)). If the pH of the nickel solution is less than 3 (especially less than 2), hydrogen sulfide (H) will be produced when alkali metal sulfides are added in the next step (g). ２If S) is generated, the amount of alkali metal sulfide is consumed in excess, resulting in a smaller amount of nickel sulfide precipitate. In other words, if the pH of the nickel solution prepared in step (a) is less than 3, an alkaline component should be added so that the pH becomes 3 or higher. Examples of alkaline components to be added here include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; and carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, magnesium carbonate, and calcium carbonate. Among these, alkali metal hydroxides are preferred, and sodium hydroxide is more preferred. It should be noted that the use of alkali metal sulfides as the alkaline component here is not preferred.

[0028] In the sulfide method, an alkali metal sulfide is then added to a nickel solution whose pH has been adjusted to 3 or higher to obtain a nickel sulfide precipitate (step (g)). This causes the nickel ions in the nickel solution to react with the alkali metal sulfide, resulting in the precipitation of nickel sulfide (NiS), which has an extremely low solubility product, thus enabling efficient nickel recovery. Examples of alkali metal sulfides include lithium sulfide (Li) ２ S), sodium sulfide (Na ２ S), potassium sulfide (K ２ S) is one example. Among these, sodium sulfide is preferred.

[0029] When adding alkali metal sulfides, it is preferable to check the pH of the nickel solution. When alkali metal sulfides are added, the pH of the nickel solution rises slowly, but when the nickel sulfide formation reaction is complete, the pH rises sharply, making it easy to determine the endpoint of the reaction. Alternatively, it is preferable to add 1.0 to 1.2 times the theoretical amount of alkali metal sulfide.

[0030] In the sulfide process, the nickel sulfide obtained above is then recovered (step (h)). Since the nickel sulfide precipitated in the nickel solution has an extremely small solubility product, it can be easily recovered by filtration or other means.

[0031] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0032] <Comparative Example 1> As a simulated waste liquid, 100 mL of a mixed solvent prepared by mixing 6 M hydrochloric acid and methanol in a 1:1 (volume ratio) was mixed with nickel chloride (NiCl) to a concentration of 40 mmol / L. ２ A nickel solution was prepared by adding 3 times the amount (120 mmol / L) of 2,2'-bipyridine. Then, sodium hydroxide (NaOH) was added until the pH of the nickel solution reached 3.0. The resulting nickel solution was stirred at 300 rpm while 0.1 mol / L of sodium sulfide (NaOH) was added. ２ S) When 40 mL of aqueous solution was slowly added, a black-red precipitate of nickel sulfide (NiS) and 2,2'-bipyridine was formed. The container was then sealed and allowed to react overnight. The resulting black-red precipitate was filtered and vacuum-dried to recover 100 mg (yield: 10%) of nickel sulfide.

[0033] <Comparative Example 2> As a simulated waste liquid, 100 mL of a mixed solvent prepared by mixing 6 M hydrochloric acid and methanol in a 1:1 (volume ratio) was mixed with nickel chloride (NiCl) to a concentration of 40 mmol / L. ２ A nickel solution was prepared by adding 2,2'-bipyridine in a quantity of 3 times its volume (120 mmol / L). Then, sodium hydroxide (NaOH) was added to the nickel solution until the pH reached 12.0 to form a nickel hydroxide precipitate. The resulting precipitate was filtered and vacuum-dried to recover 2 mg (yield: 0.5%) of nickel hydroxide.

[0034] <Example 1> 3 to 6 g of sodium perchlorate (6 to 12 times the nickel concentration as the perchloric acid concentration) was added to the nickel solution remaining in Comparative Example 2 to form tris(2,2'-bipyridine)nickel perchlorate. Further, 10 mL of 1,2-dichloroethane was added to transfer tris(2,2'-bipyridine)nickel perchlorate to the 1,2-dichloroethane phase (organic phase), and the organic phase was separated. After repeating this extraction operation 4 to 5 times, the 1,2-dichloroethane in the separated organic phase was removed by an evaporator and vacuum dried to recover 2.88 g (yield: 99%) of tris(2,2'-bipyridine)nickel perchlorate. As a result, the total yield (recovery rate) of nickel in Comparative Example 2 and Example 1 was 99.5%.

[0035] <Example 2> 3 g of sodium perchlorate was added to the nickel solution remaining in Comparative Example 2 to form tris(2,2'-bipyridine)nickel perchlorate. Then, the suspension was filtered, the precipitate was recovered and vacuum dried to recover 2.61 g (yield: 90%) of tris(2,2'-bipyridine)nickel perchlorate. As a result, the total yield (recovery rate) of nickel in Comparative Example 2 and Example 2 was 90.5%.

[0036] <Discussion> As described above, when 2,2'-bipyridine exists in the nickel solution in addition to the nickel compound, there is a limit to increasing the recovery rate of nickel by the sulfide method or the hydroxide method. However, it was found that the recovery rate of nickel can be increased by recovering the complex that exists very stably in the nickel solution as an ion pair as in the present invention. Although the recovery method of Example 2 is simpler than that of Example 1, its recovery rate depends on the solubility product of tris(2,2'-bipyridine)nickel perchlorate, so it is effective when the nickel concentration is high (several tens of mmol / L). For example, when the nickel concentration becomes 1 / 10 of that in Example 2, in order to achieve a nickel recovery rate of 90% as well, it is necessary to increase the required amount of sodium perchlorate by 3 times instead.

Claims

1. A method for recovering nickel, comprising the steps of: (a) preparing a nickel solution containing a nickel compound produced in an organic chemical reaction process and 2,2'-bipyridine; (b) adding an alkali metal perchlorate salt to the nickel solution to form a tris(2,2'-bipyridine)nickel perchlorate salt that forms an ion pair; and (c) recovering the tris(2,2'-bipyridine)nickel perchlorate salt.

2. The nickel recovery method according to claim 1, characterized in that the nickel compound is nickel halide.

3. The nickel recovery method according to claim 1, characterized in that the alkali metal perchlorate salt is potassium perchlorate or sodium perchlorate.

4. The method for recovering nickel according to claim 1, characterized in that, in step (c), a recovery solvent that separates from the nickel solution is added to move the tris(2,2'-bipyridine)nickel perchlorate to the recovery solvent phase, and after separating the recovery solvent phase, the recovery solvent is removed.

5. The method for recovering nickel according to claim 1, characterized in that the precipitated tris(2,2'-bipyridine) nickel perchlorate salt nickel is separated in step (c).

6. The nickel recovery method according to claim 1, characterized in that between step (a) and step (b), (d) a step of adjusting the pH of the nickel solution to 8 or higher to precipitate nickel hydroxide, and (e) a step of recovering the nickel hydroxide.

7. The method for recovering nickel according to claim 6, characterized in that sodium hydroxide is added to the nickel solution in step (d).

8. A method for recovering nickel according to claim 1, characterized in that between step (a) and step (b), (f) a step of adjusting the pH of the nickel solution to 3 or higher, (g) a step of adding an alkali metal sulfide to the nickel solution whose pH has been adjusted to 3 or higher to precipitate nickel sulfide, and (h) a step of recovering the nickel sulfide.

9. The method for recovering nickel according to claim 8, characterized in that sodium hydroxide is added to the nickel solution in step (f).

10. The nickel recovery method according to claim 8, characterized in that the alkali metal sulfide is sodium sulfide.

11. The method for recovering nickel according to claim 1, characterized in that the organic chemical reaction process is a process for producing an organic polymer compound.

12. The method for recovering nickel according to claim 11, characterized in that the organic polymer compound is an ion exchange resin.

13. The nickel recovery method according to claim 12, characterized in that the ion exchange resin is an anion exchange resin.

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