Deep recycling method of tire pyrolysis carbon black

Abstract

The invention belongs to the technical field of solid waste recycling, and provides a deep recycling method of tire pyrolysis carbon black, which comprises the following steps: S1, carrying out magnetic separation on the tire pyrolysis carbon black, and crushing the tire pyrolysis carbon black subjected to magnetic separation; s2, carrying out acid pickling on the tire pyrolysis carbon black by adopting a composite acid solution, and carrying out solid-liquid separation; s3, adding the tire pyrolysis carbon black subjected to acid pickling into a nitric acid solution for ultrasonic treatment, adjusting the pH to be neutral, and then adopting a sodium borohydride solution for reduction; s4, graphitizing and activating the tire pyrolysis carbon black in an inert atmosphere; and S5, carrying out particle size distribution regulation and control on the graphitized and activated tire cracking carbon black, and adding a polyacrylate binder for granulation to obtain the carbon black. The invention provides a deep recycling method of tire cracked carbon black, so that the conductivity, dispersity and chemical stability of the cracked carbon black are improved, and the finally obtained carbon black can be applied to the fields of lithium ion battery cathode materials, conductive fillers or rubber reinforcing agents and the like.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a method for the deep resource utilization of tire pyrolysis carbon black. Background Technology

[0002] Improving the resource utilization rate of bulk solid waste is crucial for promoting the low-carbon transformation of industries. Against this backdrop, the challenge of waste tire disposal arising from the development of the automotive industry and the surge in vehicle ownership urgently requires a breakthrough solution.

[0003] As a multi-component composite product containing rubber, carbon black, steel wire, and additives, waste tires can be pyrolyzed to produce carbon black-based materials, pyrolysis oil, and metal components. Among these, the performance regeneration of pyrolyzed carbon black plays a crucial role in enhancing its resource value. However, the industrial application of pyrolyzed carbon black still faces several technical challenges: 1. The ash (SiO2, CaO, etc.), metal oxides (Fe2O3, ZnO), and organic tar remaining from the pyrolysis process result in low specific surface area, poor conductivity, and poor dispersibility, making it difficult to directly use in high-value-added fields. 2. While acid washing methods (such as hydrochloric acid and sulfuric acid treatment) can partially remove ash, they easily generate acidic wastewater and have low efficiency in removing metal impurities; high-temperature graphitization treatment is energy-intensive and economically unfeasible. 3. The deterioration of interfacial compatibility caused by impurities leads to a decrease in the tensile strength of composite materials, making it difficult to meet the technical standards of the tire / cable industry.

[0004] In view of the shortcomings of the prior art, the present invention provides a process for deep purification, modification and high-value application of pyrolysis carbon black for tires, so as to improve the conductivity, dispersibility and chemical stability of pyrolysis carbon black, enabling it to be used in the fields of lithium-ion battery anode materials, conductive fillers or rubber reinforcing agents. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the deep resource utilization of tire pyrolysis carbon black, which involves deep purification, modification and high-value application of tire pyrolysis carbon black to improve its conductivity, dispersibility and chemical stability, enabling it to be used in fields such as lithium-ion battery anode materials, conductive fillers or rubber reinforcing agents.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for deep resource utilization of tire pyrolysis carbon black includes the following steps:

[0008] S1. Magnetic separation is performed on the tire pyrolysis carbon black to remove metal impurities such as steel wire and iron filings contained therein, and the magnetically separated tire pyrolysis carbon black is crushed.

[0009] S2. A composite acid solution is used to pickle tire pyrolysis carbon black and perform solid-liquid separation to further reduce the ash content in the carbon black. The waste acid obtained from solid-liquid separation is used to remove dissolved impurities, and its effective content is tested and replenished. It can be reused for pickling.

[0010] S3. Add the acid-washed tire pyrolysis carbon black to a nitric acid solution for ultrasonic treatment, then adjust the pH to neutral with NaOH, and then reduce it with sodium borohydride (NaBH4) solution to increase the density of oxygen-containing functional groups on the surface.

[0011] S4. Graphitization and activation of tire pyrolysis carbon black under an inert atmosphere to improve the orderliness and conductivity of graphite microcrystals;

[0012] S5. The graphitized and activated tire pyrolysis carbon black is granulated by adjusting the particle size distribution using an air jet mill and adding polyacrylate binder to obtain carbon black.

[0013] Furthermore, in S1, the particles are crushed to a particle size ≤50μm.

[0014] Furthermore, the composite acid solution described in S2 is composed of a mixture of hydrochloric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is 2-5 mol / L and the concentration of hydrofluoric acid is 1-3 mol / L.

[0015] Furthermore, the solid-liquid ratio in S2 is 1g:5mL~10mL.

[0016] Furthermore, the pickling time in S2 is 1–3 hours, and the pickling temperature is 60–80°C. This process removes metals, metal oxides, and silica from the carbon black ash.

[0017] Furthermore, the concentration of the nitric acid solution in S3 is 30%.

[0018] Furthermore, the amount of sodium borohydride solution used in S3 is 5% to 10% of the mass of the acid-washed tire pyrolysis carbon black.

[0019] Furthermore, the concentration of sodium borohydride solution in S3 is 1% to 3%.

[0020] Furthermore, the inert gas mentioned in S4 is nitrogen.

[0021] Furthermore, the graphitization and activation process in S4 includes the following steps:

[0022] The temperature is increased to 1800–2200℃ at a heating rate of 3–10℃ / min, and held for 1–2 hours. After graphitization, the temperature is reduced to 900–1000℃, and CO2 is introduced for activation treatment for 2–3 hours.

[0023] Furthermore, a carbon source can be added during the graphitization stage in S4; the carbon source is either glucose or phenolic resin; the amount of carbon source added is 5% to 15% of the mass of tire pyrolysis carbon black. Introducing a carbon source for co-pyrolysis during high-temperature graphitization can generate a nano-carbon layer coating on carbon black particles in situ, thereby improving electrochemical performance.

[0024] Furthermore, the D50 in the particle size distribution of S5 is 0.5–5 μm.

[0025] Furthermore, the amount of acrylate binder used in S5 is 0.1% to 1% of the mass of carbon black after the particle size of the air jet mill is adjusted.

[0026] The beneficial effects of this invention are:

[0027] 1. In this invention, an HCl-HF composite pickling system is used to remove metal oxides (Fe2O3, ZnO) and ash (SiO2) in stages. HCl preferentially dissolves Fe / Zn salts, and HF removes silicates.

[0028] 2. Carboxyl / hydroxyl groups are introduced through liquid-phase oxidation with nitric acid, followed by selective reduction with NaBH4 to construct highly active adsorption sites.

[0029] 3. HCl / HF in pickling waste liquid can be further recovered and reused, thereby reducing the amount of secondary waste generated and alleviating environmental pressure.

[0030] 4. This invention provides a method for the deep resource utilization of pyrolysis carbon black in tires, which improves the conductivity, dispersibility and chemical stability of pyrolysis carbon black. The carbon black obtained can be used in the fields of lithium-ion battery anode materials, conductive fillers or rubber reinforcing agents. Attached Figure Description

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Figure 1 This is a process flow diagram of a deep resource utilization method for tire pyrolysis carbon black according to the present invention.

[0033] Figure 2 This is a scanning electron microscope image of the original carbon black in Example 1 of this invention;

[0034] Figure 3 This is a scanning electron microscope image of the modified carbon black in Example 1 of this invention;

[0035] Figure 4 These are the XRD patterns of carbon black before and after treatment in Example 1 of this invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example

[0038] Example 1

[0039] This embodiment provides a method for the deep resource utilization of tire pyrolysis carbon black, including the following steps:

[0040] S1. Use a magnetic separator to perform magnetic separation on tire pyrolysis carbon black (initial ash content 15%, Fe content 0.8%), and then crush the magnetically separated tire pyrolysis carbon black to a particle size ≤50μm.

[0041] S2. The crushed tire pyrolysis carbon black was acid-washed and solid-liquid separated using a composite acid solution. The solid-liquid ratio was 1g:5mL, the acid washing time was 2h, and the acid washing temperature was 70℃.

[0042] The composite acid solution used in the pickling process is a mixture of HCl and HF in a concentration ratio of 2:1, which controls the ash content to be reduced to 2.5% and the Fe content to <0.05%.

[0043] S3. Add the acid-washed tire pyrolysis carbon black to a nitric acid solution (concentration of 30%) and sonicate for 1 hour. Then adjust the pH to neutral with NaOH and reduce it with a sodium borohydride solution (concentration of 1%). The amount of sodium borohydride solution used is 5% of the carbon black mass, which can effectively increase the density of oxygen-containing functional groups on the surface.

[0044] S4. Under a nitrogen atmosphere, the temperature is increased to 1800℃ at a heating rate of 3℃ / min for graphitization reaction, and the temperature is maintained for 1 hour. After the reaction is completed, the temperature is reduced to 900℃, and CO2 is introduced for activation treatment for 2 hours to obtain conductive carbon black.

[0045] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 0.5 μm, and 0.1% polyacrylate binder is added for granulation to obtain carbon black.

[0046] Example 2

[0047] The only difference compared to Example 1 is:

[0048] Replace the solid-liquid ratio of 1g:5mL in S2 with a solid-liquid ratio of 1g:7mL.

[0049] Example 3

[0050] The only difference compared to Example 1 is:

[0051] Replace the solid-liquid ratio of 1g:5mL in S2 with a solid-liquid ratio of 1g:10mL.

[0052] Example 4

[0053] The only difference compared to Example 1 is:

[0054] The composite acid solution used in the pickling process in S2, which is HCl and HF in a concentration ratio of 2:1, is replaced with a composite acid solution of HCl and HF in a concentration ratio of 3:1.

[0055] Example 5

[0056] The only difference compared to Example 1 is:

[0057] The composite acid solution used in the pickling process in S2 is replaced by a composite acid solution of HCl and HF with a concentration ratio of 3:3, instead of HCl and HF with a concentration ratio of 2:1.

[0058] Example 6

[0059] The composite acid solution used in the pickling process in S2 is replaced by a composite acid solution of HCl and HF with a concentration ratio of 2:1, which is replaced by a composite acid solution of HCl and HF with a concentration ratio of 5:2.

[0060] Example 7

[0061] The only difference compared to Example 1 is:

[0062] Replace the sodium borohydride solution (1% concentration) in S3 with a sodium borohydride solution (3% concentration).

[0063] Example 8

[0064] Replace the sodium borohydride solution in S3, which is 5% of the carbon black mass, with a sodium borohydride solution that is 10% of the carbon black mass.

[0065] Example 9

[0066] The only difference compared to Example 1 is:

[0067] S4. Under a nitrogen atmosphere, the temperature is increased to 2000℃ at a heating rate of 8℃ / min for graphitization reaction, and the temperature is maintained for 1 hour. After the reaction is completed, the temperature is reduced to 1000℃, and CO2 is introduced for activation treatment for 2 hours to obtain conductive carbon black.

[0068] Example 10

[0069] The only difference compared to Example 1 is:

[0070] S4. Under a nitrogen atmosphere, the temperature is increased to 1800℃ at a heating rate of 3℃ / min to carry out a graphitization reaction. During the graphitization stage, a carbon source, glucose, is added at a rate of 5% of the mass of the tire pyrolysis carbon black. The temperature is maintained for 1 hour. After the reaction is completed, the temperature is lowered to 900℃, and CO2 is introduced for activation treatment for 2 hours to obtain conductive carbon black.

[0071] Example 11

[0072] The only difference compared to Example 1 is:

[0073] S4. Under a nitrogen atmosphere, the temperature is increased to 1800℃ at a heating rate of 3℃ / min to carry out a graphitization reaction. During the graphitization stage, a carbon source, glucose, is added. The amount of carbon source added is 15% of the mass of tire pyrolysis carbon black. The temperature is maintained for 1 hour. After the reaction is completed, the temperature is lowered to 900℃, and CO2 is introduced for activation treatment. The activation time is 2 hours to obtain conductive carbon black.

[0074] Example 12

[0075] The only difference compared to Example 1 is:

[0076] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 5μm, and 0.1% polyacrylate binder is added for granulation to obtain carbon black.

[0077] Example 13

[0078] The only difference compared to Example 1 is:

[0079] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 0.5 μm, and 1% polyacrylate binder is added for granulation to obtain carbon black.

[0080] Comparative Example

[0081] Comparative Example 1

[0082] The only difference compared to Example 1 is:

[0083] Replace the solid-liquid ratio of 1g:5mL in S2 with a solid-liquid ratio of 1g:4mL.

[0084] Comparative Example 2

[0085] The only difference compared to Example 1 is:

[0086] Replace the solid-liquid ratio of 1g:5mL in S2 with a solid-liquid ratio of 1g:12mL.

[0087] Comparative Example 3

[0088] The only difference compared to Example 1 is:

[0089] The composite acid solution used in the pickling process in S2 is replaced by a composite acid solution of HCl and HF with a concentration ratio of 1:1, instead of HCl and HF with a concentration ratio of 2:1.

[0090] Comparative Example 4

[0091] The only difference compared to Example 1 is:

[0092] The composite acid solution used in the pickling process in S2 is replaced by a composite acid solution of HCl and HF with a concentration ratio of 2:1, which is replaced by a composite acid solution of HCl and HF with a concentration ratio of 5:4.

[0093] Comparative Example 5

[0094] The only difference compared to Example 1 is:

[0095] Replace the sodium borohydride solution (1% concentration) in S3 with a sodium borohydride solution (0.8% concentration).

[0096] Comparative Example 6

[0097] The only difference compared to Example 1 is:

[0098] Replace the sodium borohydride solution (concentration of 1%) in S3 with a sodium borohydride solution (concentration of 3.2%).

[0099] Comparative Example 7

[0100] The only difference compared to Example 1 is:

[0101] S4. Under a nitrogen atmosphere, the temperature is increased to 1600℃ at a heating rate of 3℃ / min for graphitization reaction, and the temperature is maintained for 1 hour. After the reaction is completed, the temperature is reduced to 900℃, and CO2 is introduced for activation treatment for 2 hours to obtain conductive carbon black.

[0102] Comparative Example 8

[0103] The only difference compared to Example 1 is:

[0104] S4. Under a nitrogen atmosphere, the temperature is increased to 1800℃ at a heating rate of 3℃ / min for graphitization reaction, and the temperature is maintained for 1 hour. After the reaction is completed, the temperature is reduced to 750℃, and CO2 is introduced for activation treatment for 2 hours to obtain conductive carbon black.

[0105] Comparative Example 9

[0106] The only difference compared to Example 1 is:

[0107] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 0.3 μm, and 0.1% polyacrylate binder is added for granulation to obtain carbon black.

[0108] Comparative Example 10

[0109] The only difference compared to Example 1 is:

[0110] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 6μm, and 0.1% polyacrylate binder is added for granulation to obtain carbon black.

[0111] Comparative Example 11

[0112] The only difference compared to Example 1 is:

[0113] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 0.5 μm, and 0.05% polyacrylate binder is added for granulation to obtain carbon black.

[0114] Comparative Example 12

[0115] The only difference compared to Example 1 is:

[0116] S5. The particle size distribution is controlled by an air jet mill to maintain D50 at 0.5 μm, and 1.3% polyacrylate binder is added for granulation to obtain carbon black.

[0117] Performance testing

[0118] (1) Testing: Electron microscopy and X-ray diffraction were performed on the untreated tire pyrolysis carbon black in Example 1. The electron microscopy results are as follows: Figure 2 As shown;

[0119] The carbon black product obtained in Example 1 was subjected to electron microscopy and X-ray diffraction. The electron microscopy results are as follows: Figure 3 As shown, the XRD patterns before and after carbon black treatment are as follows: Figure 4 As shown.

[0120] Depend on Figure 1 and Figure 2 It can be seen that, compared with the original sample, the modified carbon black exhibits improved lattice distortion, reduced amorphous regions, increased crystalline portions, and more ordered microcrystal arrangement.

[0121] Depend on Figure 3 It can be seen that, compared to the original sample, the peaks of the carbon black treated in Example 1 shifted to the right and became narrower, indicating that the interlayer spacing of the treated carbon black decreased and its crystallinity increased. This improves the graphitization degree of the carbon black, thereby increasing its electrical conductivity to some extent.

[0122] (2) Conductive carbon black was prepared from the carbon black obtained in Examples 1-13 and Comparative Examples 1-12. The specific surface area and tap density of the conductive carbon black were tested, and the test results are shown in Table 1:

[0123] Table 1

[0124]

[0125]

[0126] As can be seen from the data in Table 1, compared with Comparative Examples 1-12, the conductive carbon black prepared using the carbon black obtained in Examples 1-13 has a superior specific surface area and tap density, thus effectively enhancing the conductivity of the composite material. Combining Comparative Examples 1-12 and Examples 1-13, it is evident that the parameter limitations in each step of the carbon black preparation process using tire pyrolysis carbon black affect the conductivity of the carbon black.

[0127] (3) Application: The carbon black obtained in Examples 1-13 and Comparative Examples 1-12 was used as a negative electrode material in lithium-ion batteries and tested. The initial discharge capacity and coulombic efficiency of the negative electrode material were tested according to GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". The test results are shown in Table 2.

[0128] Table 2

[0129]

[0130]

[0131] As can be seen from the data in Table 3, the initial discharge capacity and coulombic efficiency of the negative electrode materials produced by the processes in Examples 1-13 are higher than those produced by the processes in Comparative Examples 1-12. This shows that the initial discharge capacity and coulombic efficiency of the negative electrode materials are reduced when carbon black obtained by different process parameters is used. Therefore, the deep resource utilization method of tire pyrolysis carbon black provided by the present invention can obtain carbon black with excellent conductivity and high chemical stability, thereby producing negative electrode materials with good discharge performance.

[0132] (4) Application: The carbon black obtained in the examples and comparative examples was mixed with styrene-butadiene rubber at a ratio of 20%. The changes in tensile strength of styrene-butadiene rubber before and after the addition of carbon black were compared. The test results are shown in Table 3.

[0133] Table 3

[0134]

[0135] As can be seen from Table 3, the improvement in mechanical properties of carbon black prepared in Comparative Examples 1-12 as a reinforcing material added to styrene-butadiene rubber is lower than that of carbon black obtained in Examples 1-13. This shows that the mechanical properties of carbon black obtained with different process parameters are different. Therefore, the deep resource utilization method of tire pyrolysis carbon black provided by the present invention can effectively control the particle size distribution of carbon black, enhance the dispersion performance and mechanical properties of carbon black, and thus effectively enhance its interaction with the rubber matrix.

[0136] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0137] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for deep resource utilization of tire pyrolysis carbon black, characterized in that, Includes the following steps: S1. Perform magnetic separation on the tire pyrolysis carbon black, and then crush the magnetically separated tire pyrolysis carbon black; S2. Tire pyrolysis carbon black is acid-washed and solid-liquid separation is performed using a composite acid solution; S3. Add the acid-washed tire pyrolysis carbon black to a nitric acid solution and sonicate it to adjust the pH to neutral. Then reduce it with sodium borohydride solution. S4. Graphitization and activation of tire pyrolysis carbon black under an inert atmosphere; S5. The particle size distribution of the graphitized and activated tire pyrolysis carbon black is controlled, and polyacrylate binder is added for granulation to obtain carbon black.

2. The method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, S1 is crushed to a particle size ≤50μm.

3. The method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The composite acid solution described in S2 is a mixture of hydrochloric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is 2-5 mol / L and the concentration of hydrofluoric acid is 1-3 mol / L.

4. The method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The solid-liquid ratio in S2 is 1g:5mL~10mL; And / or, the pickling time in S2 is 1 to 3 hours, and the pickling temperature is 60 to 80°C.

5. The method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The amount of sodium borohydride solution used in S3 is 5% to 10% of the mass of the acid-washed tire pyrolysis carbon black.

6. The method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The concentration of sodium borohydride solution in S3 is 1% to 3%.

7. A method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The graphitization and activation process in S4 includes the following steps: The temperature is increased to 1800–2200℃ at a heating rate of 3–10℃ / min, and held for 1–2 hours. After graphitization, the temperature is reduced to 900–1000℃, and CO2 is introduced for activation treatment for 2–3 hours.

8. A method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, A carbon source may be added during the graphitization stage in S4; the carbon source is one of glucose or phenolic resin; the amount of carbon source added is 5% to 15% of the mass of tire pyrolysis carbon black.

9. A method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, In S5, the particle size distribution shows a D50 of 0.5–5 μm.

10. A method for deep resource utilization of tire pyrolysis carbon black according to claim 1, characterized in that, The amount of acrylate binder used in S5 is 0.1% to 1% of the mass of carbon black after particle size adjustment.

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