Cobalt-manganese leaching agent, preparation method thereof and application of cobalt-manganese leaching agent in recovery of waste lithium batteries

Abstract

The invention provides a cobalt-manganese leaching agent, a preparation method thereof and application of the cobalt-manganese leaching agent in recycling of waste lithium batteries, the cobalt-manganese leaching agent comprises trialkyl methyl ammonium iodide and an alcohol compound, and cobalt-manganese and nickel-lithium in the waste lithium batteries can be effectively separated to obtain leaching liquid containing cobalt and manganese; the method comprises the following steps: diluting and thermally treating a leaching solution containing cobalt and manganese to obtain a manganese dioxide precipitate, obtaining a cobalt precipitate by using tannic acid, and roasting to obtain high-purity Co2O3; according to the cobalt-manganese leaching agent, use of highly corrosive mineral acid is avoided, the process is simple, the condition is mild, and the metal separation degree is high.

Description

Technical Field

[0001] The present invention relates to the field of recycling of waste lithium batteries, and particularly to a cobalt and manganese leaching agent, a preparation method thereof, and an application thereof in recycling waste lithium batteries. Background Art

[0002] Currently, China has become the world's largest new energy vehicle market, followed by a large number of scrapped batteries, which are converted into a mass of about 500,000 tons. The treatment of such a huge volume of waste batteries will become a thorny problem.

[0003] On the one hand, waste lithium batteries contain a large number of toxic and harmful chemical substances, such as heavy metals and organic solvents, which are harmful to the environment and human body; on the other hand, waste lithium batteries have a large number of valuable metal resources, such as lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn). It is easier to extract metals from waste lithium batteries with high metal content and few impurities than from natural minerals or brines with low metal content. Therefore, the harmless treatment of waste lithium batteries is of great significance for protecting the ecological environment and realizing resource reuse.

[0004] In the prior art, the recycling methods of waste lithium batteries include hydrometallurgy, pyrometallurgy, mechanical physical method, and fire-hydrometallurgy combined process; among them, the hydrometallurgy process is an efficient metal recycling technology, which can achieve efficient and cost-effective metal recycling. However, due to the increasing variety of cathode materials in lithium-ion batteries, it has become more and more difficult to recycle waste lithium batteries using traditional hydrometallurgy processes. Therefore, there is an urgent need to propose an innovative and sustainable hydrometallurgy process to extract cobalt and manganese from the cathode of waste lithium batteries. Summary of the Invention

[0005] To solve the technical problems in the background art, the present invention proposes a cobalt and manganese leaching agent, which includes trialkylmethylammonium iodide and an alcohol compound.

[0006] In the present invention, the cobalt and manganese leaching agent has a stronger complexing ability for cobalt and manganese ions, and in the leaching system, S Co / Li = 32700, S Co / Ni = 15500, S Mn / Li = 34700, S Mn / Ni = 15900, that is, there is a relatively high separation factor (S) value between cobalt and manganese elements and nickel and lithium elements, and the cobalt and manganese elements can be effectively separated from the nickel and lithium elements.

[0007] The trialkylmethylammonium iodide is one of trihexylmethylammonium iodide, triheptylmethylammonium iodide, trioctylmethylammonium iodide, or trinonylmethylammonium iodide;

[0008] Preferably, the trialkylmethylammonium iodide is trioctylmethylammonium iodide.

[0009] The alcohol compound is one of methanol, ethanol, isopropanol, n-butanol, ethylene glycol or glycerol;

[0010] Preferably, the alcohol compound is glycerol.

[0011] The weight ratio of the alcohol compound to the trialkylmethylammonium iodide is 1:0.4 - 1.3.

[0012] In the present invention, when the weight ratio of trioctylmethylammonium iodide to glycerol is 1:0.4 - 1.3, a hydrogen bond network is generated inside the cobalt-manganese leaching agent.

[0013] The present invention provides a method for preparing the above cobalt-manganese leaching agent, which is obtained by mixing the trialkylmethylammonium iodide and the alcohol compound, and the mixing temperature is 50 - 80 °C.

[0014] The present invention also provides an application of the above cobalt-manganese leaching agent or the cobalt-manganese leaching agent obtained by the above preparation method in recycling waste lithium batteries.

[0015] It includes the following steps:

[0016] S1. Disassemble and crush the waste lithium battery to obtain pretreated lithium nickel cobalt manganese oxide cathode powder;

[0017] S2. React the pretreated lithium nickel cobalt manganese oxide cathode powder with the cobalt-manganese leaching agent to obtain a leaching solution, then heat-treat the leaching solution, and after solid-liquid separation, obtain a filtrate and a manganese precipitate;

[0018] S3. React the filtrate with tannic acid, and after solid-liquid separation, obtain a cobalt precipitate.

[0019] In the present invention, the main component of the waste lithium battery cathode powder is lithium nickel cobalt manganese oxide, and the cobalt-manganese leaching agent can separate cobalt and manganese from nickel and lithium. In the obtained leaching solution, Mn mainly exists in the form of 4+ (OH - )3(H2O)] + , and cobalt mainly exists in the form of 3+ (I - )4] - .

[0020] In step S2, the weight ratio of the pretreated lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent is 1:1 - 4.

[0021] In step S2, before the heat treatment, it also includes diluting the leaching solution with a diluent;

[0022] Preferably, the diluent is deionized water;

[0023] Preferably, the heat treatment temperature is 120 - 150 °C.

[0024] In the present invention, the water dilution and hydrothermal treatment will destroy the hydrogen bond network of the cobalt - manganese leaching agent. Under heating conditions, the hydroxyl ligand of Mn decomposes to form MnO2·H2O, that is, [Mn 4+ (OH - )3(H2O)] + thermally decomposes, and the Mn - O bond breaks. As [Mn 4+ (OH - )3(H2O)] + decomposes, the content of Mn in the obtained leaching solution decreases, forming MnO2, resulting in the selective precipitation of manganese metal. During the precipitation of manganese, the cobalt complex is not affected.

[0025] In step S3, the concentration of tannic acid in the filtrate is 2 - 4 g / L;

[0026] Preferably, before the filtrate reacts with tannic acid, the pH of the filtrate is adjusted to 3.5;

[0027] Preferably, the solid - liquid separation is vacuum filtration.

[0028] In the present invention, after the tannic acid is added to the filtrate, a cobalt - tannin complex precipitate is formed. After the pH of the filtrate is adjusted to 3.5 and under the condition of 60 °C, the precipitation rate of cobalt is greater than 99%, that is, the cobalt element in the filtrate is basically completely precipitated. After roasting the precipitate, high - purity Co2O3 is obtained.

[0029] Advantages of the present invention:

[0030] (1) The cobalt - manganese leaching agent used in the present invention avoids the use of strongly corrosive mineral acids in the recycling of waste lithium batteries, and the process is simple and the conditions are mild;

[0031] (2) The cobalt - manganese leaching agent of the present invention has a very good complexing effect on cobalt and manganese, and can selectively leach cobalt and manganese elements in waste lithium batteries under the interference of nickel and lithium metals;

[0032] (3) The present invention adopts dilution and heat treatment to effectively destroy the hydrogen bond network of the leaching solution and separately separate manganese elements in the form of MnO2 precipitate;

[0033] (4) By adjusting the temperature, pH of the filtrate and the addition amount of tannic acid in the filtrate, the cobalt in the filtrate precipitates in the form of a cobalt - tannin complex, and the precipitation rate is greater than 99%, and finally high - purity Co2O3 is obtained. Description of the Drawings

[0034] Figure 1 It is the electrospray mass spectrometry diagram of the cobalt-manganese leaching solution before and after dilution and heat treatment in Example 1;

[0035] Figure 2 It is the SEM diagram of the MnO2 precipitate and Co2O3 in Example 1. Specific embodiments

[0036] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in combination with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0038] Below, the technical solutions of the present invention will be described more clearly and completely in combination with specific examples and comparative examples.

[0039] Example 1

[0040] This example provides a cobalt-manganese leaching agent, and its preparation method includes the following steps:

[0041] Take 55 g of ionic liquid trioctylmethylammonium iodide and 50 g of glycerol and place them in a beaker. Stir continuously at 60 °C at a speed of 200 r / min for 3 h to obtain the above cobalt-manganese leaching agent;

[0042] This example also provides an application of the cobalt-manganese leaching agent in the recycling of waste lithium batteries, which specifically includes the following steps:

[0043] (1) Disassemble the waste lithium battery to obtain the cathode powder body, pulverize it with a ball mill, and pass it through a 300-mesh sieve after pulverization to obtain the pretreated lithium nickel cobalt manganese oxide cathode powder body;

[0044] (2) Add the lithium nickel cobalt manganese oxide cathode powder body to the cobalt-manganese leaching agent prepared in Example 1 (the weight ratio of the lithium nickel cobalt manganese oxide cathode powder body to the cobalt-manganese leaching agent is 1:2.65), stir at 60 °C at a speed of 500 rpm for 10 minutes to obtain a mixture, and then centrifuge the mixture at 5000 r / min for 15 min to separate it into two phases, obtaining the cobalt-manganese leaching solution and the metal accompaniment. Dilute and heat-treat the cobalt-manganese leaching solution, that is, dilute the cobalt-manganese leaching solution with deionized water (the volume ratio of the cobalt-manganese filtrate to deionized water is 1:5), keep it at 130 °C for 2 h, repeat three times, and filter to obtain the MnO2 precipitate and the cobalt-containing filtrate;

[0045] (3) Adjust the pH of the cobalt-containing filtrate to 3.5 with ammonia water (25%), then add tannic acid (the concentration of tannic acid in the cobalt-containing filtrate is 3 g / L), react at 60 °C for 2 h, and more than 99% of the cobalt in the cobalt-containing filtrate precipitates in the form of cobalt-tannin complex. Vacuum filter to obtain the cobalt-tannin complex precipitate, wash it with sulfuric acid (pH = 2) by stirring at 60 °C for 30 min, and then calcine the precipitate in a muffle furnace at 550 °C for 3 hours to finally obtain high-purity Co2O3.

[0046] Figure 1 is the electrospray mass spectrometry diagram of the cobalt-manganese leaching solution before and after dilution and heat treatment in Example 1. It can be seen from Figure 1 that in the cobalt-manganese leaching solution, Mn mainly exists in the form of [Mn 4+ (OH - )3(H2O)] + , and cobalt mainly exists in the form of [Co 3+ (I - )4] - . After the cobalt-manganese leaching solution is diluted with water and heat-treated, the abundance value of [Mn 4+ (OH - )3(H2O)] + decreases significantly, which is because water dilution and heat treatment will destroy the hydrogen bond network of the cobalt-manganese leaching solution. Among them, under heating conditions, the hydroxyl ligand of manganese is prone to decomposition reaction due to its relatively low chemical bond energy, that is, [Mn 4+ (OH - )3(H2O)] + undergoes thermal decomposition, the Mn-O bond breaks, and finally MnO2·H2O is formed. Other components in the solution are relatively stable under this condition and do not undergo similar decomposition reactions, enabling the selective precipitation of manganese ions.

[0047] Figure 2 is the SEM diagram of MnO2 precipitate and Co2O3 in Example 1; it can be seen from Figure 2 that both the MnO2 precipitate and Co2O3 obtained in Example 1 exhibit a relatively regular crystal structure.

[0048] Example 2

[0049] This example proposes a cobalt-manganese leaching agent, and its preparation method includes the following steps:

[0050] Take 60 g of ionic liquid tri-nonylmethylammonium iodide and 50 g of glycerol and place them in a beaker. Stir continuously at 60 °C and a rotation speed of 300 r / min for 2 h to obtain the above cobalt-manganese leaching agent;

[0051] This embodiment also provides an application of a cobalt-manganese leaching agent in the recycling of waste lithium batteries, which specifically includes the following steps:

[0052] (1) Disassemble the waste lithium battery to obtain the cathode powder, pulverize it with a ball mill, and pass it through a 300-mesh sieve after pulverization to obtain the pretreated lithium nickel cobalt manganese oxide cathode powder;

[0053] (2) Add the lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent prepared in Example 2 (the weight ratio of the lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent is 1:2.75), stir at a speed of 500 rpm at 60 °C for 10 minutes to obtain a mixture, and then centrifuge the mixture at 5000 r / min for 20 min to separate it into two phases, obtaining the cobalt-manganese leaching solution and the metal accompanying substances. Dilute and heat-treat the cobalt-manganese leaching solution, that is, dilute the cobalt-manganese leaching solution with deionized water (the volume ratio of the cobalt-manganese filtrate to deionized water is 1:5), keep it at 150 °C for 2 h, repeat three times, and after filtration, obtain MnO2 precipitate and cobalt-containing filtrate;

[0054] (3) Adjust the pH of the cobalt-containing filtrate to 3.5 with ammonia water (20%), then add tannic acid (the concentration of tannic acid in the cobalt-containing filtrate is 3 g / L), react at 60 °C for 2 h, and more than 99% of the cobalt in the cobalt-containing filtrate precipitates in the form of cobalt-tannin complex. Vacuum filter to obtain the cobalt-tannin complex precipitate, wash it with sulfuric acid (pH = 2) by stirring at 60 °C for 25 min, and then calcine the precipitate in a muffle furnace at 550 °C for 3 h to completely burn the tannin, and finally obtain high-purity Co2O3.

[0055] Example 3

[0056] This embodiment provides a cobalt-manganese leaching agent, and its preparation method includes the following steps:

[0057] Take 50 g of ionic liquid tri-nonylmethylammonium iodide and 50 g of ethylene glycol and place them in a beaker, and continuously stir at a speed of 300 rpm at 60 °C for 2 h to obtain the above cobalt-manganese leaching agent;

[0058] This embodiment also provides an application of a cobalt-manganese leaching agent in the recycling of waste lithium batteries, which specifically includes the following steps:

[0059] (1) Disassemble the waste lithium battery to obtain the cathode powder, pulverize it with a ball mill, and pass it through a 300-mesh sieve after pulverization to obtain the pretreated lithium nickel cobalt manganese oxide cathode powder;

[0060] (2) Add lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent prepared in Example 3 (the weight ratio of lithium nickel cobalt manganese oxide cathode powder to cobalt-manganese leaching agent is 1:3.50), stir at a speed of 500 rpm at 70 °C for 8 minutes to obtain a mixture, and then centrifuge the mixture at 5000 r / min for 20 min to separate it into two phases, obtaining cobalt-manganese leaching solution and metal concomitants. Dilute and heat-treat the cobalt-manganese leaching solution, that is, dilute the cobalt-manganese leaching solution with deionized water (the volume ratio of cobalt-manganese filtrate to deionized water is 1:5), and keep it at 140 °C for 2 h. Repeat three times, and after filtration, obtain MnO2 precipitate and cobalt-containing filtrate;

[0061] (3) Adjust the pH of the cobalt-containing filtrate to 3.5 with ammonia water (20%), then add tannic acid (the concentration of tannic acid in the cobalt-containing filtrate is 3 g / L), and react at 60 °C for 2 h. More than 99% of the cobalt in the cobalt-containing filtrate precipitates in the form of cobalt-tannin complexes. Vacuum filter to obtain cobalt-tannin complex precipitate, wash the precipitate with sulfuric acid (pH = 2) by stirring at 60 °C for 25 min, and then calcine the precipitate in a muffle furnace at 550 °C for 3 hours to completely burn the tannin, and finally obtain high-purity Co2O3.

[0062] Comparative Example 1

[0063] This comparative example proposes a cobalt-manganese leaching agent, and its preparation method is the same as that of Example 1;

[0064] This comparative example also proposes an application of the cobalt-manganese leaching agent in the recycling of waste lithium batteries, which is the same as that of Example 1, except that "stir at a speed of 500 rpm at 60 °C for 10 minutes" in step (2) is changed to "stir at a speed of 500 rpm at 60 °C for 3 minutes".

[0065] Comparative Example 2

[0066] This comparative example proposes a cobalt-manganese leaching agent, and its preparation method is the same as that of Example 1, except that "trioctylmethylammonium iodide" is changed to "trioctylmethylammonium bromide";

[0067] This comparative example also proposes an application of the cobalt-manganese leaching agent in the recycling of waste lithium batteries, which is the same as that of Example 1, except that "add lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent prepared in Example 1" in step (2) is changed to "add lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent prepared in Comparative Example 2".

[0068] Comparative Example 3

[0069] This comparative example is the same as Example 1, except that the "cobalt-manganese leaching agent" in Example 1 is changed to "trioctylmethylammonium iodide".

[0070] In Comparative Example 3, glycerol was not used in combination with trioctylmethylammonium iodide. Compared with the cobalt-manganese leaching agent of Example 1, no effective hydrogen bond network was formed in the leaching system of Comparative Example 3, and thus effective cobalt-manganese leaching of the lithium nickel cobalt manganese oxide cathode powder could not be achieved, and naturally the subsequent selective precipitation of cobalt and manganese could not be completed.

[0071] Calculate the leaching rates of cobalt and manganese in the above examples and comparative examples. Table 1 shows the leaching rate data of cobalt and manganese in each example and comparative example;

[0072] Table 1 Leaching rate data of cobalt and manganese under different conditions in each example and comparative example

[0073]

[0074] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A cobalt-manganese leaching agent, characterized in that, The cobalt-manganese leaching agent includes trialkylmethylammonium iodide and an alcohol compound.

2. The cobalt-manganese leaching agent according to claim 1, characterized in that, The trialkylmethylammonium iodide is one of trihexylmethylammonium iodide, triheptylmethylammonium iodide, trioctylmethylammonium iodide or trinonylmethylammonium iodide; Preferably, the trialkylmethylammonium iodide is trioctylmethylammonium iodide.

3. The cobalt-manganese leaching agent according to claim 1 or 2, characterized in that, The alcohol compound is one of methanol, ethanol, isopropanol, n-butanol, ethylene glycol or glycerol; Preferably, the alcohol compound is glycerol.

4. The cobalt-manganese leaching agent according to any one of claims 1 to 3, characterized in that, The weight ratio of the alcohol compound to trialkylmethylammonium iodide is 1:0.4 - 1.

3.

5. A method for preparing the cobalt-manganese leaching agent according to any one of claims 1-4, characterized in that, The cobalt-manganese leaching agent is obtained by mixing the trialkylmethylammonium iodide and the alcohol compound, and the mixing temperature is 50 - 80 °C.

6. Application of the cobalt-manganese leaching agent according to any one of claims 1 - 4 or the cobalt-manganese leaching agent obtained by the preparation method according to claim 5 in recycling waste lithium batteries.

7. The application of the cobalt-manganese leaching agent according to claim 6 in recycling waste lithium batteries, characterized in that, It includes the following steps: S1. Disassemble and crush the waste lithium battery to obtain pretreated lithium nickel cobalt manganese oxide cathode powder; S2. React the pretreated lithium nickel cobalt manganese oxide cathode powder with the cobalt-manganese leaching agent to obtain a leaching solution, then heat-treat the leaching solution, and after solid-liquid separation, obtain a filtrate and a manganese precipitate; S3. React the filtrate with tannic acid, and after solid-liquid separation, obtain a cobalt precipitate.

8. The application of the cobalt-manganese leaching agent according to claim 7 in the recycling of waste lithium batteries, characterized in that, In step S2, the weight ratio of the pretreated lithium nickel cobalt manganese oxide cathode powder to the cobalt-manganese leaching agent is 1:1 - 4.

9. The application of the cobalt-manganese leaching agent according to claim 7 or 8 in recycling waste lithium batteries, characterized in that, In step S2, before the heat treatment, it also includes diluting the leaching solution with a diluent; Preferably, the diluent is deionized water; Preferably, the heat treatment temperature is 120 - 150 °C.

10. The application of the cobalt-manganese leaching agent according to any one of claims 7-9 in recycling waste lithium batteries, characterized in that, In step S3, the concentration of tannic acid in the filtrate is 2 - 4 g / L; Preferably, before the filtrate reacts with tannic acid, the pH of the filtrate is adjusted to 3.5; Preferably, the solid-liquid separation is vacuum filtration.

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