Method for removing fluorine element in black powder

Abstract

The invention provides a method for removing fluorine in black powder, and relates to the technical field of battery recovery. The removal method comprises the following steps: S1, mixing black powder with industrial acid to obtain a mixed material; s2, the mixed material is subjected to first roasting and second roasting in sequence, and an acidified roasted material is obtained; wherein the temperature of the first roasting is T1, the temperature of the second roasting is T2, T2 is larger than T1, the fluorine element in the black powder can be effectively removed, and the follow-up treatment cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling, and in particular, relates to a method for removing fluorine element in black powder. Background Art

[0002] With the development of 3C equipment and electric vehicles, the number of waste ternary batteries has increased year by year, and there is an urgent need to recycle waste ternary batteries to achieve energy recycling and reuse. Waste ternary batteries need to be discharged first to ensure safety; then they need to be disassembled to separate the positive and negative electrodes in the battery, and the electrodes are crushed and powdered, and then sieved to obtain black powder rich in Li, Ni, Co, and Mn. This black powder contains a variety of valuable metal elements, such as lithium (Li), nickel (Ni), cobalt (Co), manganese (Mn), etc. In the subsequent recycling process, the black powder will be further processed to extract valuable metal elements from it, but the black powder also contains a certain amount of harmful elements, such as fluorine (F), especially lithium hexafluorophosphate (LiPF6). 6 ) and polyvinylidene fluoride (PVDF) and other fluorine-containing compounds. During the recycling process, if the fluorine element is not effectively removed, a large amount of fluorine-containing byproducts will be produced, which will have a negative impact on the subsequent treatment process, such as affecting the performance of the positive electrode material and corroding the production equipment. Currently, most fluorine removal methods are through adsorption or pyrolysis, but there are problems such as high cost and low removal rate. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for removing fluorine element in black powder, so as to solve the problems of high cost and low removal rate in the existing black powder defluorination process.

[0004] In order to achieve the above object, the first aspect of the present invention provides a method for removing fluorine element in black powder, comprising:

[0005] S1, mixing black powder with industrial acid to obtain a mixed material;

[0006] S2, performing a first roasting and a second roasting on the mixed material in sequence to obtain an acidified roasted material; wherein the temperature of the first roasting is T1, and the temperature of the second roasting is T2, satisfying: T2>T1.

[0007] Further, T2≥1.5T1, preferably, T2=(1.5~2.5)T1.

[0008] Further, T1 is 300°C to 330°C; and / or T2 is 650°C to 750°C.

[0009] Furthermore, the first calcination time is 60 min to 90 min; and / or the second calcination time is 60 min to 90 min.

[0010] Further, the industrial acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, and acetic acid;

[0011] Preferably, the industrial acid comprises sulfuric acid and nitric acid in a volume ratio of (0.5-1):(0.5-1).

[0012] Furthermore, the mass ratio of black powder to industrial acid is 1:(1.06-1.3).

[0013] Furthermore, the mass content of fluorine element in the black powder is 0.5% to 8%.

[0014] Furthermore, the black powder includes waste ternary positive electrode materials; the chemical formula of the waste ternary positive electrode materials is LiNi 1-x- y Co x Mn y O 2 , 0<x<0.5, 0<y<0.5.

[0015] Furthermore, the mass content of lithium in the waste ternary positive electrode material is 5% to 7%, the mass content of nickel is 20% to 40%, the mass content of cobalt is 6% to 8%, and the mass content of manganese is 5% to 7%.

[0016] Furthermore, the mass content of fluorine in the acidified roasting material is ≤0.05%.

[0017] By applying the technical solution of the present invention, the fluorine element in the black powder is effectively removed through a two-stage roasting process with increasing temperature, combined with a specific industrial acid treatment, thereby reducing the subsequent processing cost and the potential pollution to the environment. The metal elements in the acidified roasted material obtained after treatment can be more effectively recycled and reused in battery manufacturing, which significantly reduces the battery production cost and promotes the sustainable utilization of waste battery resources. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0019] As described in the background technology, the existing black powder defluorination process has the problems of high cost and low removal rate. In order to solve the above technical problems, the present application provides a method for removing fluorine from black powder, comprising:

[0020] S1, mixing black powder with industrial acid to obtain a mixed material;

[0021] S2, performing a first roasting and a second roasting on the mixed material in sequence to obtain an acidified roasted material; wherein the temperature of the first roasting is T1, and the temperature of the second roasting is T2, satisfying: T2>T1.

[0022] The black powder in the present application refers to the black powder obtained by separating the positive and negative electrodes in the battery recycling pretreatment process, and then powdering the positive and negative electrodes together and sorting them.

[0023] First, the black powder is mixed with industrial acid to promote the chemical reaction and decomposition of the fluorine element. During the mixing process, the black powder fully reacts with the acid to form a mixture with a certain viscosity, similar to mud. This mud-like mixture helps to maintain the uniformity and stability of the material during the roasting process and promotes the reaction.

[0024] Next, the mixture needs to go through two roasting processes, the first roasting and the second roasting. The temperature of the first roasting is set to T1, and the temperature of the second roasting is set to T2, and the condition of T2>T1 is satisfied. Roasting at different temperatures can specifically decompose different types of fluorine-containing compounds. The first roasting (T1): Usually carried out at a relatively low temperature, this step is mainly to decompose lithium hexafluorophosphate (LiPF 6 ) and other fluorides that can be decomposed at lower temperatures. Within this temperature range, the fluorine element in the fluoride is converted into a gas form (such as HF) and released. Second calcination (T2): After the first calcination, the material is subjected to a second calcination at a higher temperature. This step is mainly to decompose fluorinated polymers such as polyvinylidene fluoride (PVDF) that can only be decomposed at high temperatures. Through high-temperature calcination, the fluorine element in PVDF is also converted into a gas form and released, further reducing the fluorine content.

[0025] Under the catalytic action of industrial acid, LiPF is calcined in two stages to 6 Both PVDF and HF are decomposed into POF 3 , CH 2 CF 2 The fluorine element in the black powder is separated and removed by the gas phase, thereby achieving efficient separation. The specific reaction equation is as follows:

[0026] LiPF 6 →LiF+PF 5

[0027] LiF+H+→HF↑+Li+

[0028] PF 5 +H + +H 2 O→POF 3 ↑+HF↑

[0029] (-CH 2 -CF 2 -) n +H + →(-CH 2=CF-) n +HF↑

[0030] (-CH 2 -CF 2 -)n+H+→CH 2 CF 2 ↑+CH 2 CHF↑+HF↑

[0031] (-CH 2 -CF 2 -) n +H + →CH 2 =CH 2 +C 2 H 6 +C 3 H 8 +HF↑

[0032] Through the above two-stage roasting process, most of the fluorine elements in the black powder can be effectively removed, so that the pressure and cost of defluorination are reduced when the acidified roasted material is subsequently leached. At present, the adsorption material used for F removal at the back end is a defluorinating agent, which is relatively expensive. At the same time, less F in the leachate can also reduce corrosion to the equipment, reduce subsequent processing costs and environmental risks, and improve the safety and environmental protection of the entire battery recycling process.

[0033] By adjusting the specific values ​​of T1 and T2, the method can be optimized for specific fluoride types and contents, thereby improving the versatility and adaptability of the method. In some embodiments, T2 ≥ 1.5T1. Different types of fluorides have different thermal stabilities. 6 Fluorides such as fluorine can be decomposed at lower temperatures, while fluorinated polymers such as PVDF require higher temperatures to completely decompose. By limiting T2 ≥ 1.5T1, it can be ensured that the temperature in the second calcination stage is high enough to effectively decompose fluorides with different thermal stabilities, thereby improving the overall removal rate of the fluorine element. Secondly, the fluorides may only be partially decomposed in the first calcination stage, while the high temperature in the second calcination stage can further promote the decomposition of the remaining fluorides, ensuring that the fluorine element is completely removed, reducing the complexity and cost of subsequent processing. In addition, in the first calcination stage, the lower temperature helps to control the formation of by-products and reduce unnecessary chemical reactions, while in the second calcination stage, the high temperature can ensure the complete decomposition of the main target fluorides, while reducing the production of new by-products by incompletely decomposed substances at high temperatures, thereby improving the controllability of the recovery process and product quality.

[0034] Therefore, limiting the second calcination temperature T2 to at least 1.5 times the first calcination temperature T1 can ensure that fluorides with different thermal stabilities can be effectively decomposed at an appropriate temperature, which helps to improve the removal efficiency of fluorine, optimize energy use, improve operational safety, and enhance the adaptability and cost-effectiveness of the method.

[0035] In some preferred embodiments, T2=(1.5-2.5)T1, which can also be understood as T2 / T1=1.5-2.5, such as 1.5, 1.8, 2, 2.2, 2.5 or a range consisting of any two of them.

[0036] The present invention does not limit the specific values ​​of T1 and T2, as long as the above requirements are met, and the specific values ​​can be determined according to actual needs. In some embodiments, T1 is 300°C to 330°C, such as 300°C, 310°C, 320°C, 330°C or a range consisting of any two thereof; in some embodiments, T2 is 650°C to 750°C, such as 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C or a range consisting of any two thereof.

[0037] In some embodiments, the first calcination time is 60 min to 90 min; and / or, the second calcination time is 60 min to 90 min. By limiting the calcination time to 60 min to 90 min, it can be ensured that at the temperature set by T1 and T2, the reactants have enough time to undergo a sufficient chemical reaction, thereby converting the fluorine element into a gas form (such as HF) and completely releasing it, thereby improving the removal rate of the fluorine element. At the same time, completing the calcination within a limited time range can reduce unnecessary side reactions caused by long-term high-temperature treatment and avoid the generation of more by-products, such as oxides of other elements in the air.

[0038] Industrial acid can be an acidic compound widely used in industrial production. In some embodiments, the industrial acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, and acetic acid. Industrial acid is mainly used to promote the decomposition or dissolution of fluoride in the material for subsequent recovery and treatment. In some preferred embodiments, the industrial acid includes at least one of sulfuric acid and nitric acid, specifically, the industrial acid includes sulfuric acid and nitric acid in a volume ratio of (0.5-1): (0.5-1). Further, the concentration of sulfuric acid is 96%-98%, the concentration of nitric acid is 65%-68%, the concentration of hydrochloric acid is 36%-38%, the concentration of carbonic acid is 5%-30%, the concentration of phosphoric acid is >85%, and the concentration of acetic acid is >99%, which can promote the decomposition of fluoride in black powder.

[0039] The present invention does not limit the mass ratio of black powder to industrial acid, as long as a mixed material is formed. The mass ratio of black powder to industrial acid is 1:(1.06-1.3), such as 1:1.06, 1:1.08, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3 or a range consisting of any two of them.

[0040] The method for removing fluorine from black powder of the present invention is applicable to black powders with different fluorine contents. In some embodiments, the mass content of fluorine in the black powder is 0.5% to 8%. According to the different mass contents of fluorine in the black powder, the amount of industrial acid added, the roasting temperature and time and other parameters can be adjusted to match the treatment of black powders with different fluorine contents.

[0041] The mass content of fluorine in the black powder is 0.5% to 8%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% or any two thereof.

[0042] The black powder may include conventional battery positive electrode materials in the art, such as lithium cobalt oxide, lithium manganese oxide, nickel cobalt manganese ternary positive electrode materials, etc. In some embodiments, the black powder includes waste ternary positive electrode materials; the chemical formula of the waste ternary positive electrode materials is LiNi 1-x-y Co x Mn y O 2 , 0<x<0.5, 0<y<0.5.

[0043] Specifically, the mass content of lithium in the waste ternary positive electrode material is 5% to 7%, the mass content of nickel is 20% to 40%, the mass content of cobalt is 6% to 8%, and the mass content of manganese is 5% to 7%.

[0044] In some embodiments, the mass content of fluorine in the acidified roasted material is ≤0.05%, which indicates that the fluorine content can be significantly reduced by the above specific removal method.

[0045] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0046] In the following examples, the concentration of sulfuric acid is 98%, the concentration of phosphoric acid is 90%, the concentration of hydrochloric acid is 38%, the concentration of nitric acid is 68%, the concentration of acetic acid is >99%, and the concentration of carbonic acid is 30%.

[0047] Example 1

[0048] In the black powder of this embodiment, the mass content of lithium element is 6.7%, the mass content of nickel element is 39.8%, the mass content of cobalt element is 7.18%, the mass content of manganese element is 6%, and the mass content of fluorine element is 1.26%.

[0049] The method for removing fluorine from black powder in this embodiment comprises:

[0050] S1, mixing sulfuric acid and nitric acid in a volume ratio of 1:1 to obtain industrial acid solution; mixing black powder and industrial acid solution in a mass ratio of 1:1.2, stirring uniformly, to obtain a mixed material;

[0051] S2, calcining the mixture at 330°C for 90 min, and further calcining at 650°C for 90 min to obtain an acidified calcined material.

[0052] Example 2

[0053] In the black powder of this embodiment, the mass content of lithium element is 6.7%, the mass content of nickel element is 39.8%, the mass content of cobalt element is 7.18%, the mass content of manganese element is 6%, and the mass content of fluorine element is 1.26%.

[0054] The method for removing fluorine from black powder in this embodiment comprises the following steps:

[0055] S1, mixing sulfuric acid, phosphoric acid and hydrochloric acid in a volume ratio of 1:1:1 to obtain industrial acid solution; mixing black powder and the industrial acid solution in a mass ratio of 1:1.06, stirring uniformly, and obtaining a mixed material;

[0056] S2, calcining the mixture at 330°C for 90 min, and further calcining at 650°C for 90 min to obtain an acidified calcined material.

[0057] Example 3

[0058] In the black powder of this embodiment, the mass content of lithium element is 6.7%, the mass content of nickel element is 39.8%, the mass content of cobalt element is 7.18%, the mass content of manganese element is 6%, and the mass content of fluorine element is 1.26%.

[0059] The method for removing fluorine from black powder in this embodiment comprises the following steps:

[0060] S1, mixing nitric acid and acetic acid in a volume ratio of 1:1 to obtain industrial acid solution; mixing black powder and the industrial acid solution in a mass ratio of 1:1.3, stirring uniformly, to obtain a mixed material;

[0061] S2, calcining the mixture at 330°C for 90 min, and further calcining at 650°C for 90 min to obtain an acidified calcined material.

[0062] Example 4

[0063] In the black powder of this embodiment, the mass content of lithium element is 6.7%, the mass content of nickel element is 39.8%, the mass content of cobalt element is 7.18%, the mass content of manganese element is 6%, and the mass content of fluorine element is 1.26%.

[0064] The method for removing fluorine from black powder in this embodiment comprises the following steps:

[0065] S1, mixing carbonic acid and hydrochloric acid in a volume ratio of 1:1 to obtain industrial acid liquid; mixing black powder and the industrial acid liquid in a mass ratio of 1:1.2, stirring uniformly, to obtain a mixed material;

[0066] S2, calcining the mixture at 300°C for 90 min, and further calcining at 700°C for 90 min to obtain an acidified calcined material.

[0067] Example 5

[0068] In the black powder of this embodiment, the mass content of lithium element is 6.7%, the mass content of nickel element is 39.8%, the mass content of cobalt element is 7.18%, the mass content of manganese element is 6%, and the mass content of fluorine element is 1.8%.

[0069] The method for removing fluorine from black powder in this embodiment comprises the following steps:

[0070] S1, using sulfuric acid as industrial acid liquid; mixing black powder and industrial acid liquid in a mass ratio of 1:1.2, stirring uniformly, and obtaining a mixed material;

[0071] S2, calcining the mixture at 330°C for 90 min, and further calcining at 650°C for 90 min to obtain an acidified calcined material.

[0072] Example 6

[0073] The mass content of lithium in the black powder of this embodiment is 5.38, the mass content of nickel is 36.51%, the mass content of cobalt is 6.89%, the mass content of manganese is 6%, and the mass content of fluorine is 5.22%.

[0074] The method for removing fluorine from black powder in this embodiment comprises the following steps:

[0075] S1, sulfuric acid and hydrochloric acid in a volume ratio of 1:1 are used as industrial acid liquid; black powder and the industrial acid liquid in a mass ratio of 1:1.2 are mixed, and stirred uniformly to obtain a mixed material;

[0076] S2, calcining the mixture at 330°C for 90 min, and further calcining at 650°C for 90 min to obtain an acidified calcined material.

[0077] Example 7

[0078] The difference from Example 1 is that the black powder and the industrial acid liquid are mixed in a mass ratio of 1:1.5.

[0079] Example 8

[0080] The difference from Example 1 is that the mixed material is calcined at 400° C. for 90 min and then calcined at 500° C. for 90 min.

[0081] Comparative Example 1

[0082] The mass content of lithium in the black powder of this comparative example is 6.7%, the mass content of nickel is 39.8%, the mass content of cobalt is 7.18%, the mass content of manganese is 6%, and the mass content of fluorine is 1.26%.

[0083] The method for removing fluorine element from black powder in this comparative example comprises the following steps:

[0084] S1, using sulfuric acid as industrial acid liquid; mixing black powder and industrial acid liquid in a mass ratio of 1:1.2, stirring uniformly, and obtaining a mixed material;

[0085] S2, calcining the mixed material at 220° C. for 90 min to obtain an acidified calcined material.

[0086] Comparative Example 2

[0087] The mass content of lithium in the black powder of this comparative example is 3.83%, the mass content of nickel is 24.8%, the mass content of cobalt is 3.79%, the mass content of manganese is 2.74%, and the mass content of fluorine is 1.8%.

[0088] The method for removing fluorine element from black powder in this comparative example comprises the following steps:

[0089] S1, using sulfuric acid as industrial acid liquid; mixing black powder and industrial acid liquid in a mass ratio of 1:1.2, stirring uniformly, and obtaining a mixed material;

[0090] S2, calcining the mixed material at 220° C. for 90 min to obtain an acidified calcined material.

[0091] Comparative Example 3

[0092] The mass content of lithium in the black powder of this comparative example is 6.7%, the mass content of nickel is 39.8%, the mass content of cobalt is 7.18%, the mass content of manganese is 6%, and the mass content of fluorine is 1.26%.

[0093] The method for removing fluorine element from black powder in this comparative example comprises the following steps:

[0094] The black powder was calcined at 330°C for 90 min and then calcined at 650°C for 90 min to obtain an acidified calcined material.

[0095] Comparative Example 4

[0096] The mass content of lithium in the black powder of this comparative example is 6.7%, the mass content of nickel is 39.8%, the mass content of cobalt is 7.18%, the mass content of manganese is 6%, and the mass content of fluorine is 1.26%.

[0097] The method for removing fluorine element from black powder in this comparative example comprises the following steps:

[0098] The black powder was calcined at 250°C for 90 minutes and then calcined at 700°C for 90 minutes to obtain an acidified calcined material.

[0099] Comparative Example 5

[0100] The mass content of lithium in the black powder of this comparative example is 3.83%, the mass content of nickel is 24.8%, the mass content of cobalt is 3.79%, the mass content of manganese is 2.74%, and the mass content of fluorine is 1.8%.

[0101] The method for removing fluorine element from black powder in this comparative example comprises the following steps:

[0102] The black powder was calcined at 330°C for 90 min and then calcined at 650°C for 90 min to obtain an acidified calcined material.

[0103] Comparative Example 6

[0104] The difference from Example 1 is that the black powder is calcined at 650° C. for 90 min.

[0105] The F removal rate is calculated according to F removal rate = 1-(mass of fluorine element in the acidified roasted material / mass of fluorine element in the black powder).

[0106] The test results are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] According to Table 1, the embodiments can achieve a relatively high F removal rate. When the acid addition ratio is greater than 1.06%, the F removal rate is higher than 98%, which can significantly reduce the F content in the black powder and reduce the defluorination pressure at the rear end. However, when no acid is added (Comparative Examples 3 to 5), even if there are two stages of roasting for defluorination, the total F removal rate is still very low, only 36.19% to 41.29%, and a high total F removal effect cannot be achieved. Similarly, even in the case of acid addition (Comparative Examples 1 to 2), only under the condition of one-stage roasting, because PVDF fails to decompose, the total F removal rate is still relatively low, only 55.86% to 65.53%, which can achieve a high total F removal effect. Although Example 7 has a high F removal rate, the mixed acid ratio is too high. On the one hand, the cost is relatively high. On the other hand, the material will become thinner after the acid is mixed, and the production operation is more difficult. In addition, the roasting will cause foaming and bubbling.

[0111] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing fluorine from black powder, characterized in that: include: S1, mixing black powder with industrial acid to obtain a mixed material; S2, performing a first roasting and a second roasting on the mixed material in sequence to obtain an acidified roasted material; wherein the temperature of the first roasting is T1, and the temperature of the second roasting is T2, satisfying: T2>T1.

2. The removal method according to claim 1, characterized in that: T2≥1.5T1, preferably, T2=(1.5~2.5)T1.

3. The removal method according to claim 2, characterized in that: T1 is 300°C to 330°C; and / or T2 is 650°C to 750°C.

4. The removal method according to any one of claims 1 to 3, characterized in that: The first calcination time is 60 min to 90 min; and / or the second calcination time is 60 min to 90 min.

5. The removal method according to any one of claims 1 to 3, characterized in that: The industrial acid includes at least one of sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, phosphoric acid, and acetic acid; preferably, the industrial acid includes the following in a volume ratio of (0.5-1): (0.5~1) of sulfuric acid and nitric acid.

6. The removal method according to claim 5, characterized in that: The mass ratio of the black powder to the industrial acid is 1:(1.06-1.3).

7. The removal method according to any one of claims 1 to 3, characterized in that: The mass content of fluorine element in the black powder is 0.5% to 8%.

8. The removal method according to any one of claims 1 to 3, characterized in that: The black powder comprises waste ternary positive electrode material; preferably, the chemical formula of the waste ternary positive electrode material is LiNi 1-x-y Co x Mn y O2, 0<x<0.5, 0<y<0.

5.

9. The removal method according to claim 8, characterized in that: The waste ternary positive electrode material has a lithium content of 5% to 7%, a nickel content of 20% to 40%, a cobalt content of 6% to 8%, and a manganese content of 5% to 7%.

10. The removal method according to any one of claims 1 to 9, characterized in that: The mass content of fluorine element in the acidified roasting material is ≤0.05%.

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