Leaching agent and method for leaching and recycling waste ternary cathode material

Abstract

The invention relates to a leaching agent and a method for leaching and recycling a waste ternary cathode material. The invention belongs to the field of leaching of waste cathode materials, and particularly relates to a leaching agent for leaching a waste ternary cathode material, which is composed of a hydrogen bond complex and a viscosity modifier, the hydrogen bond complex is composed of a formula A # imgabs 0 # and a formula B # imgabs 1 #; the viscosity modifier is water; the molar ratio of the formula A to the formula B to the viscosity modifier is (1-3): (1-3): (6-16). According to the method, due to the use of the leaching agent, the waste cathode material can be directly leached without being excessively activated, and in addition, the use amount of the leaching agent is small, and the leaching agent can be recycled.

Description

Technical Field

[0001] The invention belongs to the field of recycling and processing of waste lithium-ion batteries, and in particular relates to the field of leaching of waste cathode materials. Background Art

[0002] It is particularly important to recover metals from positive electrode materials (cathode materials). Among them, hydrometallurgy has the advantages of good metal separation effect and high purity of recovered products, and occupies a favorable position in market competition. However, this process faces challenges in application, such as complex steps, high energy consumption, large amount of reagents, and serious secondary pollution.

[0003] For waste cathodes, the existing means are mainly acid leaching. For example, the Chinese patent document with publication number CN116162785A discloses a method for leaching high-grade nickel matte in an integrated manner, which specifically includes mixing high-grade nickel matte powder with an oxidant and performing a first-stage roasting and a second-stage roasting, followed by an acid leaching treatment. For another example, the Chinese patent document with publication number CN117947274A discloses a method for fully extracting and separating metal elements from sulfuric acid leachate of waste ternary lithium batteries, specifically recording a scheme for leaching waste ternary lithium batteries with sulfuric acid. The Chinese patent document with publication number CN115141933A discloses a method for purifying ternary lithium battery recovery leachate, specifically recording a scheme for heating waste positive electrode materials and leaching and removing impurities at pH 5.0-6.5. For another example, the Chinese patent document with publication number CN114657380A discloses a method for selectively removing impurities from the acidic leachate of waste ternary lithium-ion batteries in steps.

[0004] In summary, most of the existing leaching processes for waste cathode materials require the use of auxiliary means such as high temperature or ball milling to enhance leaching. Even so, the leaching temperature and liquid-solid ratio are relatively high. The industry needs a high leaching recovery process that does not require too much pretreatment and can be performed in a mild and low solvent dosage. Summary of the invention

[0005] In view of the problems faced by the existing leaching of waste ternary cathode materials, the first purpose of the present invention is to provide a leaching agent for leaching waste ternary cathode materials, aiming to improve the leaching effect of waste ternary materials under low temperature and low leaching liquid-to-solid ratio.

[0006] The second purpose of the present invention is to provide a method for leaching and recovering metal elements in waste ternary cathode materials, aiming to innovatively utilize the leaching agent to improve the leaching effect of metals in waste cathode materials at a lower temperature and a lower liquid-to-solid ratio.

[0007] Most of the existing leaching processes for waste ternary cathode materials require activation leaching by means of high temperature or mechanical activation. In addition, a higher leaching temperature and a higher leaching liquid-solid ratio are still required to obtain an ideal leaching effect. This idea has a large process cost. In addition, the leaching agent is difficult to recycle and recycle, and the output of three wastes is large. In view of this problem, the present invention provides the following solutions:

[0008] A leaching agent for leaching waste ternary cathode materials, which is composed of a hydrogen bond complex and a viscosity regulator;

[0009] The hydrogen bond complex is composed of formula A and formula B;

[0010]

[0011] The viscosity modifier is water;

[0012] The molar ratio of formula A, formula B and viscosity regulator is 1-3:1-3:6-16.

[0013] The innovative research of the present invention shows that the innovative hydrogen bonding of formula A and formula B to form a eutectic, combined with the viscosity modifier and the joint control of the component ratio, can unexpectedly achieve synergy, and excellent critical metal leaching kinetics can be obtained at low leaching solvent dosage and low temperature, and excellent leaching effect can be obtained at milder temperature and lower solvent capacity. In the present invention, thanks to the use of the leaching agent, it is not necessary to do too much activation of the waste cathode material and can directly leach it. In addition, the leaching agent is used in a small amount and can be recycled.

[0014] In the present invention, the joint control of the component A, component B and viscosity modifier and the proportion is the key to synergistically improving the leaching kinetics of waste ternary cathode materials and improving the leaching effect at low temperature and low leaching agent dosage.

[0015] In the present invention, the molar ratio of formula A, formula B and viscosity modifier is 1:0.5-1.5:6-10, and more preferably 1:0.9-1.1:7.5-8.5. The present invention shows that the combined control of the components and the preferred ratios helps to further improve the leaching efficiency of waste ternary cathode materials and the leaching effect under mild conditions.

[0016] In the present invention, the viscosity of the leaching agent is 25 to 60 mPs, preferably 35 to 45 mPs. Studies have shown that at a preferred viscosity, the combined synergy between the components can be further improved, which helps to further improve the mild leaching effect of the leaching agent.

[0017] The present invention also provides a method for leaching waste ternary cathode materials, wherein the waste ternary cathode materials and the leaching agent of the present invention are mixed for leaching treatment to obtain a leaching solution.

[0018] The present invention innovatively uses the leaching agent for leaching of waste ternary cathode materials, and based on the combined control of components and proportions, an excellent leaching effect can be obtained at a lower leaching agent dosage and a lower temperature.

[0019] In the present invention, the waste ternary cathode material is waste lithium-containing nickel-cobalt-manganese oxide obtained by stripping from the positive electrode of waste lithium-ion batteries.

[0020] In the present invention, the waste ternary cathode material can be a substantially ternary cathode material that is a composite of any ternary crystal on the market. In addition, it can also be a ternary cathode waste with a low metal content that is difficult to gently leach in the industry. For example, the waste ternary cathode material can be waste of various crystals such as NCM111, NCM523, and NCM622. Taking into account the maximization of recycling value, the waste ternary cathode material can further be a mixed crystal waste ternary cathode material with a low metal content, for example, its lithium content can be 3-4wt.%, nickel content can be 18-22wt.%, cobalt content can be 4-5wt.%, and manganese content can be 7.5-8.5wt.%.

[0021] In the present invention, the temperature during the leaching process is above 15°C, and can be further 20-35°C in consideration of the effect, operation and cost. In the present invention, thanks to the innovative use of the leaching agent, it can still obtain excellent leaching effect under low temperature conditions that are difficult to effectively leach in the industry, but it should be noted that the leaching agent of the present invention can also be used at high temperature, but at low temperature, it has more advantages in operation and cost, and has more recovery value than the existing solution.

[0022] In the present invention, in the leaching stage, the weight ratio of the waste ternary cathode material to the leaching agent is 1:1 to 5, preferably 1:2.5 to 3.5. The leaching agent of the present invention can obtain excellent leaching activity at a low leaching agent dosage.

[0023] In the present invention, the leaching time is 2 hours or more, preferably 8 to 15 hours, and further preferably 9 to 11 hours.

[0024] In the present invention, the target metal can be recovered from the leaching solution obtained by leaching based on conventional means.

[0025] For example, the present invention also provides a method for recovering leached elements in waste ternary cathode materials. For example, the leaching method described in the present invention can be used to obtain a leaching solution, and a transition metal precipitant is added to the leaching agent to separate the solid and liquid to obtain transition metal precipitate slag and lithium liquid; the lithium liquid is then subjected to lithium precipitation treatment to obtain lithium slag.

[0026] In the present invention, the leaching solution is preliminarily treated to remove impurities and then a transition metal precipitant is added.

[0027] Preferably, the impurity removal treatment includes the steps of controlling the pH of the leaching solution to 3.8 to 7.5 and then separating the solid from the liquid;

[0028] Preferably, the transition metal precipitant is oxalic acid and its water-soluble salt;

[0029] Preferably, the lithium precipitation method is a process of adding a water-soluble carbonate for precipitation, or a process of introducing carbon dioxide for precipitation.

[0030] Beneficial effects:

[0031] The innovative research of the present invention shows that the innovative hydrogen bonding of formula A and formula B to form a eutectic, combined with the viscosity modifier and the joint control of the component ratio, can unexpectedly achieve synergy, and excellent critical metal leaching kinetics can be obtained at low leaching solvent dosage and low temperature, and excellent leaching effect can be obtained at milder temperature and lower solvent capacity. In the present invention, thanks to the use of the leaching agent, it is not necessary to do too much activation of the waste cathode material and can directly leach it. In addition, the leaching agent is used in a small amount and can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The infrared spectra of the components of Example 1 and the mixed leaching agent are shown in FIG.

[0033] Figure 2 The NMR spectra of the components of Example 1 and the mixed leaching agent are shown in FIG.

[0034] Figure 3 The Raman spectra of the components of Example 1 and the mixed leaching agent;

[0035] Figure 4 XRD and Raman diagrams of the positive electrode material before and after leaching in Example 1;

[0036] Figure 5 This is the SEM image of the positive electrode material before leaching in Example 1;

[0037] Figure 6 This is a SEM image of the cathode material precursor prepared by co-precipitation in Example 1; Specific implementation plan

[0038] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0039] The waste positive electrode material of the present invention is waste ternary lithium ion battery positive electrode material (LiNi x Co y Mn 1-x-y O2) as an example, which specifically includes LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, and the actual positive electrode powder obtained by disassembling ternary lithium-ion batteries, etc.

[0040] Table 1 Mass fraction of nickel, cobalt, manganese and lithium after digestion of different waste ternary lithium-ion cathode materials

[0041]

[0042] The actual positive electrode powder is a mixed crystal of ternary crystals such as NCM111, NCM523, NCM622, etc. Considering the limitation of stripping technology, the presence of a binder, a conductive agent and an anode material is also allowed.

[0043] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] Embodiment 1:

[0046] Step 1. Preparation of leaching agent:

[0047] Additive A (Formula A), additive B (Formula B) and additive C (water) were mixed in a molar ratio of 1:1:8 and heated at 60-65° C. under stirring until a transparent liquid was formed to prepare an extractant (viscosity of 39.7 mps).

[0048] Step 2. Leaching experiment: The actual positive electrode powder (component content is shown in Table 1) is mixed with the leaching agent of step 1 at a mass ratio of 1:3, and heated and stirred at 30°C for 10 hours for leaching;

[0049] Step 3. Separation experiment: After the leaching in step (2) was completed, the initial pH value of 3.8 was adjusted to 7.5 using 2M NaOH solution. Then, the solution was filtered through a filter with a pore size of 0.22 μm to remove graphite and precipitated Cu. 2+ ions. The resulting solution was mixed with an oxalic acid aqueous solution and stirred at 70°C for 2 hours to prepare a cathode material precursor by co-precipitation. Finally, a 2M Na2CO3 solution was used to completely precipitate the remaining Li+ to prepare a Li2CO3 product.

[0050] Step 4. Measure the concentration of the remaining metals in the filtrate after each step and calculate their mass fractions.

[0051] The concentrations of lithium, manganese, cobalt and nickel were determined by inductively coupled plasma emission spectrometry. The leaching rates of lithium, manganese, cobalt and nickel were calculated using the leaching rate calculation formula for valuable metals. The results are shown in Table 2.

[0052] Table 2

[0053] Metal Type lithium manganese cobalt nickel Leaching rate (%) 99.4％ 86.9％ 94.8％ 83.7％

[0054] Note: The leaching rates mentioned above refer to the leaching rates of metals in step 2.

[0055] It can be seen from Example 1 that the leaching agent with the composition and proportion described in the present invention can be adapted to the leaching effect of waste ternary cathode materials, and an excellent leaching effect can be obtained at low temperature and low leaching agent dosage.

[0056] Embodiment 2:

[0057] Compared with Example 1, the only difference is that the heating temperature in step 1 is changed, and the temperature in the leaching stage is 20°C. The leaching results are shown in Table 3.

[0058] Table 3

[0059]

[0060] It can be seen from Examples 1 and 2 that the leaching method of the present invention, thanks to the use of the leaching agent, can achieve excellent leaching effect at low temperature.

[0061] Embodiment 3:

[0062] Compared with Example 1, the only difference is that the leaching time in step 2 is changed, and the results are shown in Table 4.

[0063] Table 4

[0064]

[0065]

[0066] Embodiment 4:

[0067] Compared with Example 1, the only difference is that the positive electrode material waste to be leached used in step 2 is changed (content see Table 1). The leaching results are shown in Table 5.

[0068] Table 5

[0069]

[0070] It can be seen from Examples 1 and 4 that for different ternary materials, the method of the present invention can achieve good synchronous and gentle leaching effects. Even for substantially positive electrode powders with low metal content, ideal leaching effects can be obtained at low temperatures and low leaching agent dosages.

[0071] Embodiment 5:

[0072] Compared with Example 1, the only difference is that step 2 is changed to change the solid-liquid weight ratio in the leaching stage to 1:5. The results are shown in Table 6.

[0073] Table 6

[0074]

[0075] It can be seen from Examples 1 and 5 that by adopting the method of the present invention, a good leaching effect can be obtained at a low leaching agent dosage.

[0076] Embodiment 6:

[0077] Compared with Example 1, the only difference is that the viscosity of the leaching agent is regulated by the additive C, and the other operations and parameters are the same as those of Example 1. The results are shown in Table 7.

[0078] Table 7

[0079]

[0080]

[0081] It can be seen from Examples 1 and 6 that, under the viscosity described in the present invention, especially when the molar ratio of Formula A, Formula B, and viscosity regulator is 1:0.9-1.1:7.5-8.5 and the viscosity is controlled at 35-45 mPs, better adaptability and synergy can be obtained, and a better mild leaching effect can be obtained.

[0082] Embodiment 7:

[0083] Compared with Example 1, the only difference is that we recycle the solvent after leaching and recycle it, and the composition and other conditions of the leaching agent in the cyclic leaching stage are the same as those of the first leaching. The results are shown in Table 8. The leaching efficiency is still high in the second cycle. After three cycles, the solvent is consumed and the leaching performance decreases.

[0084] Table 8

[0085]

[0086] It can be seen from Examples 1 and 7 that the system described in the present invention, in addition to being able to achieve good mild leaching advantages, also has good cyclic leaching stability.

[0087] Embodiment 8:

[0088] Compared with Example 1, the only difference is that the ratio of additive A to additive B is changed. Other operations and parameters are the same as Example 1. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein are measured, and the leaching rate is calculated (see Table 9).

[0089] Table 9

[0090]

[0091] It can be seen from Examples 1 and 8 that a better leaching effect can be obtained by using the leaching agent at the preferred ratio of the present invention.

[0092] Comparative Example 1:

[0093] Compared with Example 1, the only difference is that the viscosity modifier (additive C) is missing in the leaching agent. Other operations and parameters are the same as in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein are measured, and the leaching rate is calculated (see Table 10).

[0094] Table 10

[0095] Metal Type lithium manganese cobalt nickel Leaching rate (%) 15.0％ 9.2％ 9.7％ 15.4％

[0096] Comparative Example 2:

[0097] Compared with Example 1, the only difference is that in step 1, when preparing the leaching agent solvent, the formula C is used. Only the additive B was replaced in an equal molar amount. Other operations and parameters were the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions, and manganese ions contained therein were measured, and the leaching rate was calculated (see Table 11).

[0098] Table 11

[0099] Metal Type lithium manganese cobalt nickel Leaching rate (%) 37.0％ 35.4％ 32.9％ 33.2％

[0100] Comparative Example 3:

[0101] Compared with Example 1, the only difference is that in step 1, when preparing the leaching agent solvent, the following combination of components is used as the leaching agent (the molar ratio of the comparative leaching agent is the same as that of Example 1), and the experimental group is composed as follows:

[0102] Group A: The leaching agent is formula D + formula B + water;

[0103] Group B: The leaching agent is Formula E + Formula B + water;

[0104] Group C: The leaching agent is formula D + formula C + water;

[0105] Group D: The leaching agent is formula E + formula C + water;

[0106]

[0107] Other operations and parameters are the same as those in Example 1. The concentrations of lithium ions, nickel ions, cobalt ions and manganese ions contained therein are measured, and the leaching rate is calculated (see Table 12).

[0108] Table 12

[0109]

[0110] It is recommended to set up a single-factor comparison case that does not adopt the key innovation points of this application, for example:

[0111] In summary, the innovative research of the present invention shows that the leaching agent of the invention can achieve efficient leaching of valuable metals in waste ternary lithium-ion batteries under mild conditions of low temperature and high solid-liquid ratio. In addition, the leaching system also has excellent cyclic leaching activity and stability.

[0112] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A leaching agent for leaching waste ternary cathode materials, characterized in that: It is composed of a hydrogen-bonded complex and a viscosity modifier; The hydrogen bond complex is composed of formula A and formula B; The viscosity modifier is water; The molar ratio of formula A, formula B and viscosity regulator is 1-3:1-3:6-16.

2. The leaching agent for leaching waste ternary cathode materials according to claim 1, characterized in that: The molar ratio of formula A, formula B and viscosity modifier is 1:0.5-1.5:6-10, and more preferably 1:0.9-1.1:7.5-8.

5.

3. The leaching agent for leaching waste ternary cathode materials according to claim 1 or 2, characterized in that: The viscosity of the leaching agent is 25-60 mPs, preferably 35-45 mPs.

4. A method for leaching waste ternary cathode materials, characterized in that: The waste ternary cathode material is mixed with the leaching agent according to any one of claims 1 to 3 for leaching treatment to obtain a leaching solution.

5. The method for leaching waste ternary cathode material according to claim 4, characterized in that: The waste ternary cathode material is waste lithium-containing nickel-cobalt-manganese oxide obtained by stripping from the positive electrode of waste lithium-ion batteries.

6. The method for leaching waste ternary cathode materials according to claim 4, characterized in that: The temperature during the leaching process is 15°C or higher, preferably 20 to 35°C.

7. The method for leaching waste ternary cathode materials according to claim 4, characterized in that: In the leaching stage, the weight ratio of the waste ternary cathode material to the leaching agent is 1:1 to 5, preferably 1:2.5 to 3.

5.

8. The method for leaching waste ternary cathode materials according to claim 4, characterized in that: The leaching time is 2 hours or more, preferably 8 to 15 hours.

9. A method for recovering leached elements from waste ternary cathode materials, characterized in that: The method according to any one of claims 4 to 8 is used to obtain a leaching solution, a transition metal precipitant is added to the leaching agent, and solid-liquid separation is performed to obtain transition metal precipitate slag and lithium liquid; The lithium liquid is then subjected to lithium precipitation treatment to obtain lithium slag.

10. The method for recovering leached elements from waste ternary cathode materials according to claim 9, characterized in that: The leachate is treated to remove impurities beforehand and then a transition metal precipitant is added; Preferably, the impurity removal treatment includes the steps of controlling the pH of the leaching solution to 3.8 to 7.5 and then separating the solid from the liquid; Preferably, the transition metal precipitant is oxalic acid and its water-soluble salt; Preferably, the lithium precipitation method is a process of adding a water-soluble carbonate for precipitation, or a process of introducing carbon dioxide for precipitation.

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