Separation and recovery method for cobalt and nickel
By using amino acids to form chromium-amino acid complexes and precipitate nickel-oxidized acid complexes by oxidizing acids, the separation and recovery problems of chromium and nickel in the prior art are solved, and low-cost and effective separation and recovery effects are achieved.
Patent Information
- Application Number
- JP2023183922
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-26
- Publication Date
- 2025-05-13
AI Technical Summary
The prior art is difficult to efficiently separate and recover chromium and nickel from chromium and nickel-containing materials at low cost, especially without the use of expensive extractants.
The separation and recovery of chromium and nickel are achieved by using amino acids such as alanine and phenylalanine, and the nickel-oxidized acid complex is precipitated by the addition of an oxidized acid.
Low-cost separation and recycling of chromium and nickel are achieved, avoiding the need for expensive extractants, and the process is relatively simple and easy to perform.
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Figure 2025073282000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a method for separately separating and recovering cobalt and nickel from a material containing cobalt and nickel. [Background technology]
[0002] The demand for low-sulfur fuels and gasoline is increasing as a result of tightening environmental regulations focused on reducing harmful emissions. In addition, there is an increasing need to process heavy crude oils that are high in sulfur, nitrogen and metals. These factors have led to an increased use of hydrodesulfurization (HDS) catalysts in oil refineries around the world. Hydrodesulfurization catalysts are often deactivated after several cycles of use due to the deposition of contaminants such as carbon (C), sulfur (S), and other metals derived from the crude oil. For this reason, used hydrodesulfurization catalysts (hereinafter also referred to as used catalysts) are disposed of as waste.
[0003] Spent catalysts generally contain high concentrations of metals (e.g., 15-30 wt% Al, 4-12 wt% Mo, 1-5 wt% Ni, 0-4 wt% Co). These metals are easily oxidized when they come into contact with the outside air, resulting in the release of harmful heavy metals into the soil and groundwater. For example, it has been reported that even in pure water with a neutral pH, molybdenum (Mo), cobalt (Co), and nickel (Ni) are eluted in large amounts from spent catalysts, and environmental problems associated with the disposal of such waste have been pointed out (e.g., see Non-Patent Document 1). For this reason, spent catalysts are classified as hazardous waste by the United States Environmental Protection Agency (USEPA) and cannot be disposed of without strict regulations.
[0004] Despite these environmental concerns, spent catalysts can be considered a potential secondary metal resource due to their high content of important transition metals and the threat of depletion of natural ores, making the recovery of metals from spent catalysts crucial for a sustainable supply of metals.
[0005] Some hydrodesulfurization catalysts contain both cobalt and nickel as active components, so discarded spent catalysts can be a valuable source for recycling cobalt and nickel, which are also found in spent batteries and laterite ores.
[0006] A common method for recovering cobalt and nickel involves strong acid leaching, which is simple and inexpensive but has the significant drawback that it is difficult to separate the cobalt and nickel from aqueous solutions.
[0007] Cobalt and nickel are adjacent in the periodic table and therefore have similar chemical properties. Separation of cobalt and nickel is extremely difficult as the metals tend to dissolve and co-precipitate together, and cannot be achieved by simple hydroxide precipitation due to their similar behavior in a given pH environment.
[0008] In recent years, solvent extraction has been used to separate cobalt and nickel, but this process is relatively costly because it requires the use of an extractant such as phosphinic acid (see non-patent literature 2 and 3). [Prior art documents] [Non-patent literature]
[0009] [Non-Patent Document 1] Angelidis, T., Tourasanidis, E., Marinou, E., and Stalidis, G. (1995). Selective dissolution of critical metals from diesel and naptha spent hydrodesulphurization catalysts. Resour. Conserv. Recycl. 13, 269-282. doi:10.1016 / 0921-3449(94)00049-b [Non-Patent Document 2] Liu, Y., Nam SH, Lee MS(2015). A study on the separation of Co(II), Ni(II), and Mg(II) by solvent extraction with cationic extractants, Bull. Korean Chem. Soc. 36 (2015) 2646-2650. doi:10.1002 / bkcs.10535 [Non-Patent Document 3] Ayanda,OS, Adekola, FA, Baba, AA, Ximba, BJ, Fatoki, OS (2013) Application of Cyanex extractant in Cobalt / Nickel separation process by solvent extraction. Int. J. Phys. Sci. 8 (3) 89-97. doi:10.5897 / IJPS12.135. Summary of the Invention [Problem to be solved by the invention]
[0010] Under these circumstances, there is a need for an inexpensive method that can separate and recover cobalt and nickel from materials containing cobalt and nickel without using expensive extractants.
[0011] An object of the present invention is to provide a method capable of inexpensively and simply separating and recovering cobalt and nickel from a material containing cobalt and nickel. [Means for solving the problem]
[0012] As a result of investigations to achieve the above object, the present inventors discovered an amino acid that can selectively precipitate and recover cobalt while nickel is eluted. This makes it possible to inexpensively and simply separate and recover cobalt and nickel by first separating and recovering cobalt from nickel, and then precipitating and recovering the eluted nickel using oxalic acid, thereby completing the present invention.
[0013] That is, the present invention is as follows. [1] A method for recovering cobalt and nickel by separating them from a material containing cobalt and nickel, comprising the steps of: a cobalt separation step of contacting the cobalt and nickel containing material with a solution containing alanine and / or phenylalanine to precipitate a cobalt-amino acid complex, and separating the precipitated cobalt-amino acid complex; a nickel separation step of adding oxalic acid to the solution from which the cobalt-amino acid complex has been separated to precipitate a nickel-oxalate complex and separating the precipitated nickel-oxalate complex; A method for separating and recovering cobalt and nickel, comprising the steps of:
[0014] [2] The method for separating and recovering cobalt and nickel according to the above [1], wherein the temperature of the solution in the nickel separation step is 60 to 80°C. [3] The method for separating and recovering cobalt and nickel according to the above [1] or [2], wherein the solution containing alanine and / or phenylalanine has a pH of 8 to 12. [4] The method for separating and recovering cobalt and nickel according to any one of [1] to [3] above, characterized in that in the nickel separation step, a nickel-oxalate complex prepared in advance is added before or immediately after the addition of the oxalic acid.
[0015] [5] The method for separating and recovering cobalt and nickel according to any one of the above [1] to [4], wherein the material containing cobalt and nickel contains molybdenum and / or vanadium. [6] The method for separating and recovering cobalt and nickel according to any one of the above [1] to [5], wherein the material containing cobalt and nickel is a waste catalyst or a battery material. Effect of the Invention
[0016] According to the method for separating and recovering cobalt and nickel of the present invention, cobalt and nickel can be separated and recovered separately from a material containing cobalt and nickel in a cheap and easy manner. [Brief description of the drawings]
[0017] [Figure 1] FIG. 2(a) is a graph showing the change in the leaching rate of cobalt in a solution containing alanine or phenylalanine, and FIG. 2(b) is a graph showing the change in the leaching rate of nickel in a solution containing alanine or phenylalanine. [Diagram 2] FIG. 1(a) is a graph showing the change in the leaching rate of cobalt in solutions containing various amino acids, and FIG. 1(b) is a graph showing the change in the leaching rate of nickel in solutions containing various amino acids. [Diagram 3] FIG. 1(a) is a graph showing the change in leaching rate of molybdenum in solutions containing various amino acids, and FIG. 1(b) is a graph showing the change in leaching rate of vanadium in solutions containing various amino acids. [Figure 4] FIG. 1 shows the change in aluminum leaching rate for solutions containing various amino acids. [Diagram 5] FIG. 1 shows the variation in nickel leaching rate in solutions containing various acids. [Figure 6] FIG. 1(a) is a graph showing the change in leaching rate of molybdenum in solutions containing various acids, and FIG. 1(b) is a graph showing the change in leaching rate of vanadium in solutions containing various acids. [Figure 7] FIG. 1 shows the concentration of nickel in an alanine leaching solution by adding a solution containing oxalic acid. [Figure 8]FIG. 1(a) is a graph showing the concentration of molybdenum in an alanine leaching solution by the addition of a solution containing oxalic acid, and FIG. 1(b) is a graph showing the concentration of vanadium in an alanine leaching solution by the addition of a solution containing oxalic acid. [Figure 9] FIG. 1 shows the effect of the addition of nickel-oxalate complex (seed crystals) on the concentration (precipitation) of nickel in an alanine leaching solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The method for separating and recovering cobalt and nickel according to the present invention is a method for separating and recovering cobalt and nickel from a material containing cobalt (Co) and nickel (Ni) (hereinafter, also simply referred to as a material), a cobalt separation step of contacting a material containing cobalt and nickel with a solution containing alanine and / or phenylalanine (hereinafter also referred to as alanine, etc.) to precipitate a cobalt-amino acid complex, and separating the precipitated cobalt-amino acid complex; a nickel separation step of adding oxalic acid to the solution from which the cobalt-amino acid complex has been separated to precipitate a nickel-oxalate complex and separating the precipitated nickel-oxalate complex; The present invention is characterized by having the following.
[0019] The method for separating and recovering cobalt and nickel of the present invention may include a step other than the cobalt separation step and the nickel separation step, such as a pretreatment step carried out before the cobalt separation step. For example, depending on the surface condition of the material containing cobalt and nickel, it is preferable to carry out a pretreatment step of washing the material with acetone or the like in advance.
[0020] The separation and recovery method of the present invention is a novel technique that utilizes the ability of alanine or the like to co-precipitate with cobalt as a cobalt-amino acid complex in order to separate cobalt and nickel from materials containing cobalt and nickel. By using amino acids that are non-toxic, non-volatile, and recyclable, it is possible to separately separate and recover cobalt and nickel at low cost, without using an expensive extractant such as phosphinic acid.
[0021] Materials that can be treated in the separation and recovery method of the present invention are not particularly limited as long as they contain cobalt and nickel (both cobalt and nickel), and examples include waste catalysts (used hydrodesulfurization catalysts, etc.), battery materials (used batteries, etc.), and ores. However, waste catalysts that contain a lot of both cobalt and nickel (high cobalt and nickel content), are expected to be used in increasing amounts in the future, and there are concerns about the impact on the environment associated with their disposal, are preferred. Note that some waste catalysts and battery materials contain molybdenum (Mo) and / or vanadium (V) in addition to cobalt and nickel.
[0022] In the method of the present invention, when treating a waste catalyst, for example, in order to remove oil and organic contaminants adhering to the surface of the material, it is preferable to carry out washing (pretreatment) with acetone or the like using equipment such as a Soxhlet extractor. Specifically, the oil-containing waste catalyst is dried and placed in a thimble filter, which is then put into a Soxhlet extractor. Next, acetone is boiled in the Soxhlet extractor to treat the waste catalyst, after which the thimble filter is removed from the Soxhlet extractor, the treated waste catalyst is washed with ethanol, and heated to evaporate the acetone.
[0023] Furthermore, materials containing cobalt and nickel may be treated as is, but it is preferable to treat them in a crushed form (e.g., in the form of fragments on the order of centimeters or even granules on the order of millimeters) or even in a pulverized form (e.g., in the form of a powder on the order of μm), since this produces a homogeneous treated material, increases the surface area, and improves the leaching efficiency. The particle size of the pulverized product is, for example, preferably in the range of 20 μm to 300 μm, more preferably in the range of 30 μm to 250 μm, and further preferably in the range of 30 μm to 200 μm. The particle size can be adjusted, for example, using a sieve, but is not particularly limited.
[0024] In the present invention, a liquid containing a reagent necessary for leaching (eluting) a metal is referred to as a leaching agent (or extractant), and the liquid after the metal has been leached (eluted) is referred to as a leaching solution (extraction solution).
[0025] Each step will now be described in detail.
[0026] [Cobalt separation process] The cobalt separation step is a step of contacting a material containing cobalt and nickel with a solution containing alanine and / or phenylalanine to precipitate a cobalt-amino acid complex (specifically, a cobalt-alanine complex and / or a cobalt-phenylalanine complex), and separating the precipitated cobalt-amino acid complex.
[0027] The solution that is brought into contact with the cobalt- and nickel-containing material is used as a metal leaching agent (extractant) to promote the formation of cobalt-amino acid complexes with the cobalt in the material and to precipitate these complexes, while the other valuable metal species, nickel (and molybdenum and vanadium, if present), remain in the solution without precipitating.
[0028] Amino acids having the above-mentioned effects include alanine and phenylalanine, with alanine being preferred.
[0029] The amount of alanine etc. added (amount of alanine etc. added per 1 mg of cobalt required to form a cobalt-amino acid complex) is preferably about 30 mg to 350 mg, more preferably about 50 mg to 300 mg, and even more preferably about 65 mg to 260 mg.
[0030] The pH of the solution containing alanine or the like is preferably 8.0 to 12.0, and in order to stably precipitate the cobalt-amino acid complex, it is more preferably 8.5 to 12.0, further preferably 9.0 to 11.5, and particularly preferably 9.5 to 11.5. The pH can be adjusted by adding an alkaline agent such as ammonia or NaOH.
[0031] The temperature of the solution during the reaction in the cobalt separation step is, for example, preferably 20 to 90°C, and more preferably 30 to 80°C.
[0032] The cobalt-amino acid complex precipitated in this step can be separated from the leachate containing other metals by solid-liquid separation means (such as filtration). Usually, the cobalt-amino acid complex is recovered together with the base material (unleached portion) of the material such as a waste catalyst. The separation of the cobalt-amino acid complex is preferably carried out, for example, 6 hours after the material is contacted with the solution containing alanine, taking into consideration the time required for the formation of the cobalt-amino acid complex, and more preferably after 2 to 4 hours in consideration of shortening the processing time.
[0033] The separated cobalt-amino acid complex can be dissolved in hot water. This allows the cobalt to be separated from the base material. The hot water is preferably, for example, about 40 to 90°C, more preferably 50 to 80°C, and even more preferably about 60 to 80°C. Cobalt can be recovered by carrying out a prescribed process from the hot water in which the cobalt-amino acid complex has been dissolved. For example, cobalt can be recovered as sulfide (CoS).
[0034] [Nickel separation process] The nickel separation step is a step of adding oxalic acid to the solution from which the cobalt-amino acid complex has been separated to precipitate a nickel-oxalate complex, and then separating the precipitated nickel-oxalate complex.
[0035] The oxalic acid added to the solution (leachate) from which the cobalt-amino acid complex was separated forms a nickel-oxalic acid complex with nickel, which precipitates. Specifically, nickel in the leachate is considered to exist as a soluble nickel-alanine complex, but by adding oxalic acid, a nickel-oxalic acid complex is newly formed in place of the nickel-alanine complex, which precipitates. At this time, molybdenum and vanadium remain dissolved in the solution after leaching. The pH of the solution to which oxalic acid has been added is, for example, about 0.5 to 2.5, preferably about 0.5 to 2.0, and more preferably about 0.7 to 1.2. In addition, when seed crystals, which will be described later, are added, the pH may be higher, and the upper limit of the pH is, for example, about 4.0.
[0036] The amount of oxalic acid added (the amount of oxalic acid added per 1 mg of nickel required to form a nickel-oxalic acid complex) is preferably about 2000 mg to 4000 mg, more preferably about 2300 mg to 3700 mg, and particularly preferably about 2500 mg to 3500 mg.
[0037] In order to complete the formation (precipitation) of the nickel-oxalate complex in a shorter time, it is preferable to adjust the temperature of the solution. The temperature of the solution is, for example, preferably 40 to 90° C., more preferably 50 to 85° C., and more preferably 60 to 80° C. When seed crystals described later are added, the temperature may be lower, and is, for example, preferably 20° C. or higher, and more preferably 30° C. or higher.
[0038] In order to form (precipitate) the nickel-oxalate complex in a shorter time, it is preferable to add the nickel-oxalate complex prepared in advance to the container before or immediately after adding oxalic acid to the solution in this step. Here, "immediately after addition" means within 1 hour after addition, and preferably within 30 minutes.
[0039] This nickel-oxalate complex serves as a seed crystal (nucleus) for the nickel in the solution to form a nickel-oxalate complex, and for example, a nickel-oxalate complex formed and separated in advance in this step can be used, but a nickel-oxalate complex prepared separately can also be used. The amount of nickel-oxalate complex added as a seed crystal is preferably added so that the concentration in the solution is 0.01 to 1 mass%, more preferably 0.1 to 1 mass%.
[0040] The nickel-oxalate complex precipitated by this process can be separated from the leachate containing the other metals by solid-liquid separation means (such as filtration). Here, nickel can be used as it is as a nickel-oxalate complex, but it may also be recovered as a sulfide (NiS) after, for example, a predetermined treatment.
[0041] The cobalt and nickel recovery of the present invention can be carried out in a batch or continuous mode. Examples of batch recovery methods include a method in which a material is supplied to a solution containing alanine or the like stored in a container, or a solution containing alanine or the like is supplied to a material stored in a container, and the material is immersed (contacted) in the solution containing alanine or the like to form a cobalt-amino acid complex, which is separated and recovered, and then oxalic acid is supplied to the solution from which the cobalt-amino acid complex was separated, or the solution from which the cobalt-amino acid complex was separated is supplied to oxalic acid stored in a container to form a nickel-oxalate complex, which is separated.
[0042] An example of a continuous leaching treatment is one in which vessels A and B are arranged in series. Specifically, a solution containing alanine, etc. is supplied to and discharged from container A filled with the material, and a cobalt-amino acid complex is formed in container A. Then, the solution containing alanine, etc. discharged from container A is supplied to and discharged from container B, and oxalic acid is added to form a nickel-oxalate complex. At this time, by preparing multiple containers A filled with the material in parallel, the supply path of the solution containing alanine, etc. can be switched for each container A, and for container A in which the cobalt-amino acid complex has been formed, the material that has been treated can be replaced with untreated material. In addition, by preparing multiple containers B corresponding to container A, the supply path of the solution from which the cobalt-amino acid complex has been separated can be switched, and at this time, for container B in which the nickel-oxalate complex has been formed, the nickel-oxalate complex can be taken out.
[0043] In another continuous method, a solution containing the material and alanine, etc. is supplied in a predetermined amount to vessel A, the cobalt-amino acid complex formed is precipitated, and a predetermined amount is discharged together with the material. Meanwhile, the leachate containing other metals is allowed to overflow and supplied to vessel B. A predetermined amount of oxalic acid is supplied to vessel B, the nickel-oxalate complex formed is precipitated, and the nickel-oxalate complex is discharged and recovered.
[0044] The supply amounts of the material and the solution containing alanine, etc. to the container A are set in consideration of the processing time (residence time) of the material in the container A. The solution containing alanine, etc. in the container A is adjusted, for example, by measuring the concentration of alanine, etc., pH, etc. periodically (intermittently) or continuously, and the leachate in the container B is adjusted, for example, by measuring the concentration of oxalic acid, temperature, pH, etc. periodically (intermittently) or continuously. The cobalt-amino acid complex and the nickel-oxalate complex precipitated in each of the containers A and B are taken out periodically (intermittently) or continuously, for example, from the bottom of the containers A and B. It is also possible to use a part of the formed nickel-oxalate complex as a seed crystal without taking it out of the container B, and to add a part of the taken-out nickel-oxalate complex to the container B. EXAMPLES
[0045] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
[0046] <Sample preparation and characterization> Spent catalyst samples were pretreated to remove oil and organic contaminants by washing with acetone using a Soxhlet extractor. Specifically, the oily spent catalyst was first dried overnight in an oven at 60 °C. Then, a 20 g sample of the spent catalyst was placed in a thimble filter and placed in a Soxhlet extractor. Next, 150 mL of acetone was added to the Soxhlet extractor and boiled. Then, the thimble filter was removed from the Soxhlet extractor, and the treated spent catalyst was washed with ethanol and left at 60 °C overnight to evaporate the acetone. Finally, the dried spent catalyst sample was crushed in an agate mortar and pestle and sieved through a sieve with mesh sizes of 75–150 μm.
[0047] To measure metal concentrations, 50 mg of the ground sample was added to a Teflon container and subjected to microwave-assisted acid digestion. Next, 10 mL of Aqua Regia (HCl 3:1 HNO3) was added to the container and left for 30 minutes. It was then heated to 210°C in a microwave for 30 minutes and held at 210°C for 15 minutes. After heating, the container was cooled and the leachate was collected by filtration, adjusted to volume, and then diluted for ICP measurement. The chemical composition of the spent catalyst, determined by acid digestion and ICP-OES analysis (ICP-OES; PerkinElmer, Optima 8300), is shown in Table 1.
[0048] [Table 1]
[0049] As shown in Table 1, the metals Co, Ni, Mo, and V were present at approximately 1.13%, 1.50%, 4.30%, and 2.00%, respectively, with Al (aluminum) being the most abundant at approximately 20.2%.
[0050] <Leaching from used catalysts by leaching agents> (Test using leaching agent containing amino acids) An Erlenmeyer flask was prepared by adding 1.5 g of the acetone-washed ground sample (material concentration 3% w / v) to 50 mL of a solution of amino acids (alanine (Ala), phenylalanine (Phe), asparagine (Asn), glutamine (Gln), aspartic acid (Asp), valine (Val), serine (Ser), cysteine (Cys), glutamic acid (Glu), histidine (His), and glycine (Gly); 0.5 M, initial pH 11) as a leaching agent.
[0051] All flasks were shaken at 150 rpm for 48 h at 45° C. Periodic sampling was performed to measure metal concentrations (Co, Ni, Mo, V, Al) by ICP-OES.
[0052] As shown in Figure 1(a), it was found that cobalt in the sample precipitated after dissolution, whether the solution contained alanine or the solution contained phenylalanine, while nickel in the sample dissolved and remained dissolved, whether the solution contained alanine or the solution contained phenylalanine, as shown in Figure 1(b).
[0053] FIG. 2 shows the results when solutions containing other amino acids were used, and also shows the results when a solution containing alanine was used for reference. As shown in Figure 2(a), it was found that cobalt in the sample was dissolved and remained dissolved when a solution containing an amino acid other than alanine was used, and nickel in the sample was dissolved and remained dissolved when a solution containing an amino acid was used, regardless of the type of amino acid, as shown in Figure 2(b). The pH remained alkaline. From the above, it was found that when a solution containing alanine and / or phenylalanine was used, cobalt (precipitated) and nickel (dissolved) could be separated.
[0054] Furthermore, as shown in Figures 3(a) and (b), it was found that molybdenum and vanadium in the sample were dissolved and remained dissolved when a solution containing amino acids was used, regardless of the type of amino acid. In other words, when a solution containing alanine or phenylalanine is used, molybdenum and vanadium in the sample are dissolved and remain dissolved. Therefore, it was found that cobalt can be separated from molybdenum and vanadium by using a solution containing alanine or phenylalanine.
[0055] As shown in FIG. 4, aluminum in the sample is not eluted from the material when a solution containing alanine and phenylalanine is used. In other words, it was found that cobalt can be separated from aluminum by using a solution containing alanine or phenylalanine.
[0056] (Tests using leaching agents containing organic and inorganic acids) As with the amino acids above, an Erlenmeyer flask was prepared in which 1.5 g of acetone-washed ground sample (material concentration 3% w / v) was added to 50 mL of organic acid (0.5 M oxalic acid (Oxa), 0.5 M citric acid (Cit)) and inorganic acid (0.5 M sulfuric acid (H2SO4)) solutions were used. As a control, a system containing 1.5 g of the same sample in 50 mL of deionized water (DI water) was used.
[0057] All flasks were shaken at 150 rpm for 48 h at 45° C. Periodic sampling was performed to measure metal concentrations (Ni, Mo, V) by ICP-OES.
[0058] As shown in FIG. 5, it was found that nickel in the sample was difficult to dissolve when an oxalic acid solution was used. On the other hand, as shown in Figures 6(a) and (b), it was found that molybdenum and vanadium in the sample remained dissolved when the oxalic acid solution was used. From the above, it was found that nickel can be separated from other metals, in this case molybdenum and vanadium, when an oxalic acid solution is used.
[0059] <Precipitation of nickel-oxalate complex from alanine leaching solution> As described above, when a used catalyst is leached with alanine, cobalt does not dissolve but precipitates, while nickel, molybdenum, and vanadium dissolve and remain dissolved. Also, as described above, when a used catalyst is leached with oxalic acid, nickel does not dissolve but precipitates, while molybdenum and vanadium remain dissolved. Therefore, it may be possible to selectively separate nickel from the alanine leachate by using oxalic acid. Therefore, in this test, we attempted to selectively precipitate nickel from the alanine leachate using oxalic acid. Nickel is present in the leachate as a soluble nickel-alanine complex, which means that in addition to competition between alanine and oxalic acid, new nickel-oxalate complexes must form and precipitate.
[0060] First, the alanine leachate was separated from the solid residue by filtration (0.45 μm). An appropriate amount of oxalic acid was dissolved in ultrapure water to prepare an oxalic acid solution (1.0 M) separately. Then, 10 mL of the leachate and 10 mL of the oxalic acid solution were mixed 1:1 (v / v) in a 50 mL Erlenmeyer flask and shaken at different temperatures (45 °C and 70 °C).
[0061] The tests were conducted twice, with samples taken periodically to measure metal (nickel, molybdenum, vanadium) concentrations.
[0062] As shown in Figure 7, when the temperature of the leachate was 70°C, the nickel concentration dropped rapidly. Precipitation was slow for the first 8 hours, but the nickel concentration decreased in the range of 8 to 20 hours, indicating that Ni precipitation progressed rapidly. On the other hand, when the temperature of the leachate was 45°C, the nickel concentration dropped, but more slowly than in the case of the higher temperatures mentioned above. It is believed that by raising the temperature of the leachate to 70°C, the complex formation between nickel and alanine became more unstable, promoting the reaction between oxalic acid and nickel, and forming nickel-oxalic acid complexes more rapidly and in larger quantities. In other words, it is believed that raising the temperature of the leachate plays an important role in determining the precipitation rate.
[0063] As shown in FIGS. 8(a) and 8(b), the molybdenum concentration and the vanadium concentration were approximately constant. From the above, it can be seen that nickel can be selectively separated from the alanine leachate to form a solid nickel-oxalate complex.
[0064] <Effect of Addition of Nickel-Oxalate Complex (Seed Crystal) on Precipitation of Nickel-Oxalate Complex> As mentioned above, nickel was successfully separated from the leachate by the precipitation method using oxalic acid, but it took a certain amount of time for the nickel-oxalic acid complex to form (precipitation began after 8 to 20 hours). Therefore, in order to promote the precipitation of nickel-oxalate complex, a test was conducted to add nickel-oxalate complex as seed crystals. The seed crystals were prepared by mixing 50 mM nickel solution (nickel sulfate) and 100 mM oxalic acid and shaking at 70 °C for several hours. The resulting precipitate was collected by filtration and dried. The precipitation test of nickel-oxalate complex was conducted by mixing 10 mL of alanine leachate containing nickel, molybdenum, and vanadium with 10 mL of oxalic acid solution (1:1 (v / v)) in a 50 mL Erlenmeyer flask, adding different amounts of seed crystals (0%, 0.1%, 0.5%), and shaking at 70 °C for 48 hours.
[0065] The tests were conducted twice, with samples taken periodically to measure metal (nickel, molybdenum, vanadium) concentrations.
[0066] As shown in Figure 9, in the system without added seed crystals, it took 48 hours for the nickel concentration to completely decrease, whereas in the system with added 0.1% and 0.5% (w / v) seed crystals, the nickel concentration decreased to approximately 0 mM in the first 4 hours. In other words, it can be seen that the addition of seed crystals promoted crystallization. The concentrations of molybdenum and vanadium did not change.
[0067] As shown above, both metals, cobalt and nickel, can be separated using alanine and phenylalanine, with cobalt being able to precipitate as a cobalt-amino acid complex while keeping nickel in a soluble form, and furthermore, nickel from this solution can be precipitated with oxalic acid. This discovery fulfilled the objective of recovering cobalt and nickel separately from each other. [Industrial Applicability]
[0068] INDUSTRIAL APPLICABILITY The present invention is industrially useful since it can separate and recover cobalt and nickel from materials containing cobalt and nickel.
Claims
1. A method for recovering cobalt and nickel from a material containing cobalt and nickel, comprising the steps of: a cobalt separation step of contacting the cobalt and nickel containing material with a solution containing alanine and / or phenylalanine to precipitate a cobalt-amino acid complex, and separating the precipitated cobalt-amino acid complex; a nickel separation step of adding oxalic acid to the solution from which the cobalt-amino acid complex has been separated to precipitate a nickel-oxalate complex and separating the precipitated nickel-oxalate complex; A method for separating and recovering cobalt and nickel, comprising the steps of:
2. 2. The method for separating and recovering cobalt and nickel according to claim 1, wherein the temperature of the solution in the nickel separation step is 60 to 80° C.
3. 2. The method for separating and recovering cobalt and nickel according to claim 1, wherein the solution containing alanine and / or phenylalanine has a pH of 8.0 to 12.
0.
4. 2. The method for separating and recovering cobalt and nickel according to claim 1, wherein in the nickel separation step, a nickel-oxalic acid complex prepared in advance is added before or immediately after the addition of the oxalic acid.
5. 2. The method for separating and recovering cobalt and nickel according to claim 1, wherein the material containing cobalt and nickel contains molybdenum and / or vanadium.
6. 6. The method for separating and recovering cobalt and nickel according to claim 1, wherein the material containing cobalt and nickel is a waste catalyst or a battery material.