Waste activated carbon modification and regeneration method and modified and regenerated activated carbon

Abstract

Disclosed in the present invention are a waste activated carbon modification and regeneration method and modified and regenerated activated carbon. The method comprises: sequentially performing chemical complexation, chemical modification and heating modification regeneration on waste activated carbon to obtain modified and regenerated activated carbon. According to the method in the present application, valuable metals in the waste activated carbon can be recycled by means of the step of chemical complexation; after recycling, the waste activated carbon is modified by means of the step of chemical modification, so that the specific surface area of the waste activated carbon can be increased, the surface functional groups thereof are increased, and the polarity thereof is increased; and then by means of the step of heating modification regeneration, most of organic matters on the waste activated carbon can be decomposed and gasified, thereby reducing the carbon loss, enhancing a pore structure of the activated carbon, and optimizing the adsorption performance of the activated carbon, obtaining the modified and regenerated activated carbon having good performance.

Description

Method for modifying and regenerating waste activated carbon and modified regenerated activated carbon Technical Field

[0001] The embodiments of the present application relate to the field of solid waste treatment technology, such as a method for modifying and regenerating waste activated carbon and modified and regenerated activated carbon. Background Art

[0002] As a porous material, activated carbon has an extremely developed internal pore structure, a large specific surface area, and a strong adsorption capacity. It is used in many industrial production fields. For example, it is used in the wet recycling process of waste batteries. Activated carbon is often used to adsorb organic matter and trace heavy metals in the aqueous and / or gas phases.

[0003] Currently, the price of activated carbon is high in the market, with high-quality activated carbon costing over 10,000 yuan per ton, and coal-based activated carbon generally priced at no less than 3,000 yuan per ton. The amount of activated carbon used in the wet recycling process for batteries is large, and the cost per use of activated carbon is high. Furthermore, because the discarded activated carbon from the wet recycling process for used batteries is considered hazardous waste, conventional landfill disposal can easily cause secondary pollution, posing an environmental risk. If it is sent for external processing, the cost of handling the hazardous waste is high, indirectly increasing the operating costs of the wet process. It can also result in the valuable metals in the discarded activated carbon not being effectively utilized, resulting in a waste of resources. Therefore, the discarded activated carbon needs to be regenerated.

[0004] Currently, there are several methods for regenerating waste activated carbon, including heating, chemical, biological, ultrasonic, and microwave. Heating and chemical regeneration are the most widely used methods in industrial activated carbon regeneration. However, for waste activated carbon generated during the wet recycling of used batteries, heating alone cannot recover the valuable metals adsorbed on the waste activated carbon, resulting in a waste of resources. Furthermore, unrecovered valuable metals accumulate in the regenerated activated carbon as ash, affecting its performance. Furthermore, chemical regeneration alone is less versatile and can only regenerate a single substance. For example, in the literature (Yang Yanling, Regeneration of Powdered Activated Carbon by Solvent Regeneration [D], Tianjin University, 2014), methanol or ethanol alone was used to regenerate waste activated carbon adsorbing a single organic compound. However, this method easily collapses and clogs the micropores, resulting in a low regeneration rate. Furthermore, repeated cycles can also cause ash accumulation, affecting the performance of the regenerated activated carbon.

[0005] In summary, it is an urgent problem to seek a process method that can effectively regenerate waste activated carbon from the wet recycling process of waste batteries, with good regeneration performance and effective recovery of valuable metals therein.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] The embodiments of the present application provide a method for modifying and regenerating waste activated carbon and modified and regenerated activated carbon. The method of the present application can recover valuable metals from waste activated carbon through a chemical complexation step. After recovery, the waste activated carbon is modified through a chemical modification step, which can increase the specific surface area of ​​the waste activated carbon, increase its surface functional groups, and increase its polarity. Then, through a heating modification and regeneration step, most of the organic matter on the waste activated carbon can be decomposed and gasified, reducing carbon loss, while increasing the pore structure of the activated carbon and optimizing the adsorption properties of the activated carbon, thereby obtaining modified and regenerated activated carbon with good performance.

[0009] In a first aspect, an embodiment of the present application provides a method for modifying and regenerating waste activated carbon, the method comprising:

[0010] The waste activated carbon is subjected to chemical complexation, chemical modification and heating modification regeneration in sequence to obtain modified regenerated activated carbon.

[0011] The present application provides a method for modifying and regenerating waste activated carbon. Through the step of chemical complexation, valuable metals in the waste activated carbon can be recovered. After recovery, the waste activated carbon is modified through the step of chemical modification, which can increase the specific surface area of ​​the waste activated carbon, increase the types and number of its surface functional groups, and increase its polarity. Then, through the step of heating modification and regeneration, most of the organic matter on the waste activated carbon can be decomposed and gasified, reducing carbon loss, while increasing the pore structure of the activated carbon and optimizing the adsorption performance of the activated carbon, thereby obtaining modified and regenerated activated carbon with good performance.

[0012] Preferably, the waste activated carbon includes waste activated carbon produced in the process of wet recycling of waste batteries; further, the waste activated carbon includes substantially adsorption-saturated activated carbon produced in the process of wet recycling of waste batteries.

[0013] Preferably, the spent activated carbon is dry.

[0014] Preferably, the waste activated carbon includes valuable metal elements and / or ash.

[0015] Preferably, the valuable metal elements in the waste activated carbon include at least one of Ni, Co and Mn elements.

[0016] Preferably, based on the total mass of the waste activated carbon as 100%, the mass fraction of the valuable metal elements is 0.5-3%, for example, it can be 0.5%, 0.7%, 1%, 1.5%, 2%, 2.5% or 3%.

[0017] Preferably, based on the total mass of the waste activated carbon as 100%, the mass fraction of the ash is 8-12%, for example, it can be 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%, etc.

[0018] Preferably, the iodine adsorption value of the waste activated carbon is 90-200 mg / g, for example, it can be 90 mg / g, 100 mg / g, 120 mg / g, 150 mg / g, 170 mg / g or 200 mg / g.

[0019] Preferably, the waste activated carbon is subjected to a physical cleaning process before the chemical complexation.

[0020] In the present application, a physical cleaning step can dissolve the free valuable metal salts and some organic matter entrained between the waste activated carbon or on the shallow surface in a solvent (such as water), thereby realizing the recovery of the valuable metal salts.

[0021] In the present application, after a stage of physical cleaning of the waste activated carbon, solid-liquid separation can be performed to obtain a stage of physically cleaned waste activated carbon and a stage of cleaning liquid containing valuable metals. The stage of cleaning liquid containing valuable metals can be recycled to recover the valuable metals.

[0022] Preferably, the physical cleaning method includes a first water immersion.

[0023] Preferably, during the first water immersion process, the mass ratio of waste activated carbon to water is 1:(10-50), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50, etc.

[0024] Preferably, the physical cleaning time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours or 3 hours.

[0025] Preferably, the specific step of the chemical complexation includes: soaking the waste activated carbon in a chemical complexation liquid.

[0026] In this application, after the waste activated carbon is soaked in a chemical complexing liquid for a period of time, solid-liquid separation is performed to obtain the chemically complexed waste activated carbon and the chemical complexing liquid containing valuable metals. The chemical complexing liquid containing valuable metals can be recycled to recover the valuable metals.

[0027] Preferably, the chemical complexing liquid includes at least one of ammonia water, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid and fruit acid.

[0028] In the present application, ammonia, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid or fruit acid can acidify or complex the valuable metal salts adsorbed in the micropores of the waste activated carbon, desorb them from some organic matter, dissolve them in the chemical complexing liquid, and further recover the valuable metal salts.

[0029] Preferably, the amount of the chemical complexing liquid added is 0.2-1 times the theoretical amount required to complex the valuable metal elements in the waste activated carbon, for example, it can be 0.2 times, 0.3 times, 0.4 times, 0.5 times, 0.7 times, 0.9 times or 1 times.

[0030] For example, if the chemical complexing liquid is ammonia water, ammonia water reacts with divalent nickel ions, Ni 2+ + 6NH3.H2O=[Ni(NH3)6] 2+ +6H2O, for divalent nickel ions, theoretically the amount of ammonia added is 6 times the amount of nickel ions. The same applies to the rest.

[0031] Preferably, the mass ratio of the waste activated carbon to the chemical complexing liquid is 1:(10-50), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50, etc.

[0032] Preferably, the chemical complexation time is 1-3 h, for example, 1 h, 1.2 h, 1.5 h, 1.7 h, 2 h, 2.2 h, 2.5 h, 2.7 h or 3 h.

[0033] Preferably, before the chemical modification, the waste activated carbon after chemical complexation is subjected to a two-stage physical cleaning.

[0034] In this application, a two-stage physical cleaning process can be used to clean and recover free valuable metal salts and chemical complexing liquid from the surface of the waste activated carbon. Through the steps of a first-stage physical cleaning process, chemical complexing, and a second-stage physical cleaning process, the valuable metals in the waste activated carbon can be fully and effectively recovered, effectively reducing the ash content in the regenerated activated carbon.

[0035] In the present application, after the waste activated carbon is subjected to two-stage physical cleaning, solid-liquid separation can be performed to obtain the waste activated carbon after the two-stage physical cleaning and the two-stage cleaning liquid containing valuable metals. The two-stage cleaning liquid containing valuable metals can be recycled to recover the valuable metals.

[0036] Preferably, the second-stage physical cleaning method includes a second water immersion.

[0037] Preferably, during the second water immersion process, the mass ratio of waste activated carbon to water is 1:(10-50), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50, etc.

[0038] Preferably, the time for the second stage physical cleaning is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours or 3 hours.

[0039] Preferably, the specific step of chemical modification includes: soaking the chemically complexed waste activated carbon in a chemical modification liquid.

[0040] In the present application, after the waste activated carbon is soaked in the chemical modification liquid for a period of time, the chemically modified waste activated carbon and the used chemical modification liquid can be obtained by solid-liquid separation, and the used chemical modification liquid can be recycled.

[0041] Preferably, the chemical modification liquid includes at least one of ammonia water, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid and fruit acid.

[0042] In the present application, ammonia, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid or fruit acid, etc., can be used to chemically modify the waste activated carbon after chemical complexation, thereby increasing its specific surface area and increasing the surface functional groups of the waste activated carbon, thereby increasing its polarity.

[0043] In the present application, the types and concentrations of the components of the chemical modification liquid and the chemical complexing liquid may be the same or different, and there is no specific limitation thereto, and there are many process options.

[0044] Preferably, the concentration of the chemical modification liquid is 0.02-0.2 mol / L, for example, it can be 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L or 0.2 mol / L, etc.

[0045] Preferably, the mass ratio of the chemically complexed waste activated carbon to the chemically modified liquid is 1:(10-50), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50, etc.

[0046] Preferably, the chemical modification time is 1-3 h, for example, 1 h, 1.2 h, 1.5 h, 1.7 h, 2 h, 2.2 h, 2.5 h, 2.7 h or 3 h.

[0047] Preferably, before the heating modification and regeneration, the chemically modified waste activated carbon is subjected to three stages of physical cleaning and physical drying in sequence.

[0048] In the present application, three-stage physical cleaning can clean and recover excess chemical modification liquid on the surface of the waste activated carbon; physical drying can reduce the moisture content of the waste activated carbon and improve the heat utilization rate of the subsequent heating process.

[0049] Preferably, the three-stage physical cleaning method includes a third water immersion.

[0050] Preferably, during the third water immersion process, the mass ratio of the waste activated carbon to water is 1:(10-50), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or 1:50, etc.

[0051] Preferably, the time for the three stages of physical cleaning is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours or 3 hours.

[0052] Preferably, the moisture content of the waste activated carbon obtained after the physical drying is less than or equal to 15%, for example, it can be 15%, 12%, 10%, 8% or 6%.

[0053] Preferably, the specific steps of the heating modification and regeneration include: mixing the chemically modified waste activated carbon with carbon materials and performing heating regeneration.

[0054] In this application, the heating modification and regeneration step can decompose and gasify most of the organic matter on the activated carbon, fully carbonize and activate carbon materials (such as asphalt and graphite), make up for the loss of activated carbon in the modification and regeneration process, reduce carbon loss, and at the same time increase the pore structure of the activated carbon and optimize the adsorption performance of the activated carbon.

[0055] Preferably, the carbon material includes pitch powder and graphite.

[0056] Preferably, the D50 particle size of the asphalt powder is 0.075-0.45 mm, for example, it can be 0.075 mm, 0.08 mm, 0.085 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm or 0.45 mm.

[0057] Preferably, the D50 particle size of the graphite is 0.85-4 mm, for example, it can be 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm or 4 mm.

[0058] Preferably, the mass ratio of the asphalt powder to graphite is 1:(1-3), for example, it can be 1:1, 1:1.2, 1:1.5, 1:1.7, 1:2, 1:2.2, 1:2.5, 1:2.7 or 1:3, etc.

[0059] Preferably, based on the mass of the chemically modified waste activated carbon being 100%, the mass fraction of the asphalt powder is 1-8%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%.

[0060] Preferably, based on the mass of the chemically modified waste activated carbon being 100%, the mass fraction of the graphite is 1-8%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%.

[0061] Preferably, the heating regeneration is segmented heating regeneration, and the segmented heating regeneration includes: first performing a first stage of heating regeneration, and then performing a second stage of heating regeneration.

[0062] Preferably, the temperature of the first stage heating regeneration is 300-700°C, for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or 700°C.

[0063] Preferably, the atmosphere of the first stage heating regeneration is an inert atmosphere, and the gas in the inert atmosphere includes N2.

[0064] Preferably, the temperature of the second stage heating regeneration is 800-1000°C, for example, it can be 800°C, 850°C, 900°C, 950°C or 1000°C.

[0065] Preferably, the gas in the atmosphere of the second-stage heating and regeneration includes CO2.

[0066] In this application, the gas in the atmosphere of the second-stage heating regeneration is adjusted to CO2 in order to gasify the residual carbon left in the activated carbon pores by the first-stage heating regeneration with the activated gas (CO2, CO) to achieve the purpose of re-forming the pores.

[0067] Preferably, the heating rate of the first stage heating regeneration and the heating rate of the second stage heating regeneration are independently 2-8°C / min, for example, they can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min, etc.

[0068] Preferably, the heating regeneration time is 20-90 min, for example, it can be 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min.

[0069] As a preferred technical solution of the present application, the method includes:

[0070] S1, a physical cleaning stage: soaking the waste activated carbon in water for 1-3 hours, and then performing solid-liquid separation, wherein the waste activated carbon includes waste activated carbon generated in the wet recovery process of waste batteries;

[0071] S2, chemical complexation: soaking the waste activated carbon obtained after solid-liquid separation in step S1 in a chemical complexation liquid for 1-3 hours, and then performing solid-liquid separation;

[0072] S3, second stage physical cleaning: the waste activated carbon obtained after solid-liquid separation in step S2 is subjected to a second water soak for 1-3 hours, and then solid-liquid separation is performed;

[0073] S4, chemical modification: soaking the waste activated carbon obtained after solid-liquid separation in step S3 in a chemical modification liquid for 1-3 hours, and then performing solid-liquid separation;

[0074] S5, three-stage physical cleaning: the waste activated carbon obtained after solid-liquid separation in step S4 is subjected to a third water soak for 1-3 hours, and then solid-liquid separation is performed;

[0075] S6, physical drying: air-drying the waste activated carbon obtained after solid-liquid separation in step S5 until the moisture content of the waste activated carbon is less than or equal to 15%;

[0076] S7, heating modification and regeneration: the waste activated carbon air-dried in step S6 is mixed with asphalt powder and graphite, and heated and regenerated in stages to obtain modified regenerated activated carbon.

[0077] Preferably, in step S5, the waste activated carbon after the third water immersion is neutral.

[0078] Preferably, the air-drying temperature in step S6 is 20-40°C, for example, 20°C, 22°C, 25°C, 30°C, 35°C or 40°C.

[0079] Preferably, the modified regenerated activated carbon obtained in step S7 is cooled and stored in a dry state.

[0080] In a second aspect, an embodiment of the present application provides a modified regenerated activated carbon, which is prepared by the method for modifying and regenerating waste activated carbon described in the first aspect.

[0081] Preferably, the modified regenerated activated carbon includes valuable metal elements and / or ash.

[0082] Preferably, the valuable metal elements in the modified regenerated activated carbon include at least one of Ni, Co and Mn elements.

[0083] Preferably, based on the total mass of the modified regenerated activated carbon as 100%, the mass fraction of the valuable metal elements is less than or equal to 0.2%, for example, it can be 0.2%, 0.19%, 0.18%, 0.15%, 0.12% or 0.1%.

[0084] Preferably, based on the total mass of the modified regenerated activated carbon being 100%, the mass fraction of the ash is less than or equal to 5%, for example, it may be 5%, 4.8%, 4.5%, 4%, 3.5%, 3% or 2%.

[0085] Preferably, the iodine adsorption value of the modified regenerated activated carbon is greater than or equal to 800 mg / g, for example, it can be 800 mg / g, 820 mg / g, 850 mg / g, 900 mg / g, 920 mg / g, 950 mg / g or 980 mg / g.

[0086] Generally, the iodine adsorption value of fresh activated carbon is greater than or equal to 900 mg / g, and the iodine adsorption value of the modified regenerated activated carbon of the present application is relatively close to it, which shows that the method of the present application can effectively modify and regenerate waste activated carbon, and the modified and regenerated activated carbon has good performance.

[0087] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0088] Compared with the related art, the beneficial effects of the embodiments of the present application are:

[0089] (1) The present invention provides a method for modifying and regenerating waste activated carbon. Through the chemical complexation step, the valuable metals in the waste activated carbon can be effectively recovered; the ash content in the regenerated activated carbon can be effectively reduced.

[0090] (2) In the method of the embodiment of the present application, after recovering the valuable metals, the waste activated carbon is modified by a chemical modification step, which can increase the specific surface area of ​​the waste activated carbon, increase the types and number of its surface functional groups, increase its polarity, and reuse the chemical modification liquid to reduce resource waste;

[0091] (3) In the method of the embodiment of the present application, after chemical modification, the heat modification and regeneration step can decompose and gasify most of the organic matter on the waste activated carbon, and the added materials such as asphalt and graphite can make up for the carbon loss during the regeneration process, increase the pore structure of the activated carbon, and optimize the adsorption performance of the activated carbon;

[0092] (4) The method of the embodiment of the present application has flexible processing conditions, and the reagents and auxiliary materials used are conventional and easily available, without the need for expensive equipment investment, and is low in cost and easy to promote;

[0093] (5) The method of the embodiment of the present application can effectively regenerate the waste activated carbon generated in the wet recycling process of waste batteries, reduce the output of hazardous waste, and reduce the cost of treating solid waste residues in the wet recycling process of waste batteries;

[0094] (6) The modified regenerated activated carbon prepared by the method of the embodiment of the present application has good regeneration performance. In the modified regenerated activated carbon, the mass fraction of valuable metal elements is less than or equal to 0.2%, and the mass fraction of ash is less than or equal to 5%; the iodine adsorption value of the modified regenerated activated carbon is greater than or equal to 800 mg / g.

[0095] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation to the technical solution of this article.

[0097] FIG1 is a schematic flow chart of a method for modifying and regenerating waste activated carbon provided in one embodiment of the present application.

[0098] FIG2 is a SEM image of the modified regenerated activated carbon prepared in Example 1 of the present application.

[0099] FIG3 is a SEM image of the modified regenerated activated carbon prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0100] The technical solution of this application is further explained below through specific implementation methods.

[0101] In one embodiment, the present application provides a method for modifying and regenerating waste activated carbon, the process of which is shown in FIG1 , and specifically includes:

[0102] S1. Performing a physical cleaning on the waste activated carbon, and after solid-liquid separation, obtaining a section of physically cleaned waste activated carbon and a section of cleaning liquid, and recovering the section of cleaning liquid;

[0103] S2. chemically complexing the waste activated carbon after the physical cleaning, and obtaining the waste activated carbon after chemical complexation and a chemical complexing liquid after solid-liquid separation, and recovering the chemical complexing liquid;

[0104] S3, performing a second-stage physical cleaning on the waste activated carbon after chemical complexation, and after solid-liquid separation, obtaining the waste activated carbon after the second-stage physical cleaning and a second-stage cleaning liquid, and recovering the second-stage cleaning liquid;

[0105] S4, chemically modifying the waste activated carbon after the second-stage physical cleaning, and obtaining chemically modified waste activated carbon and used chemically modified liquid after solid-liquid separation, wherein the used chemically modified liquid can be used again for chemical modification;

[0106] S5, performing three-stage physical washing on the chemically modified waste activated carbon, and after solid-liquid separation, obtaining the three-stage physically washed waste activated carbon;

[0107] S6. Physically drying the waste activated carbon after the three-stage physical cleaning to obtain physically dried waste activated carbon;

[0108] S7. The waste activated carbon after physical drying is subjected to heating modification and regeneration, and then cooled to obtain modified regenerated carbon.

[0109] Example 1

[0110] This embodiment provides a method for modifying and regenerating waste activated carbon, comprising the following steps:

[0111] S1: Take 50g of waste activated carbon from the wet recycling process of waste batteries, soak it in 1000mL of water for 2h, and then filter it to obtain the first cleaning liquid for recycling;

[0112] S2: The activated carbon obtained in S1 is placed in 500 mL of 0.025 mol / L citric acid solution and soaked for 1 hour, then filtered, and the obtained citric acid solution containing the valuable metals is recovered;

[0113] S3: Soak the activated carbon obtained in step S2 in 1000 mL of water for 1 hour, then filter and recover the obtained second cleaning liquid;

[0114] S4: Soak the activated carbon obtained in step S3 in 500 mL of 0.075 mol / L ammonia solution for 1 hour, then filter and recycle the obtained ammonia solution;

[0115] S5: Soak the activated carbon obtained in S4 in 1000 mL of water for 1 h, then filter;

[0116] S6: The activated carbon obtained in S5 was naturally air-dried for 2 h, and the moisture content was 14%;

[0117] S7: The activated carbon obtained in step S6 is mixed with 3% asphalt powder with a D50 particle size of 0.075mm-0.45mm and 5% graphite with a D50 particle size of 0.85mm-4mm, with a mass ratio of asphalt powder to graphite being 1:1.7, and then placed in a high-temperature furnace for heating, modification and regeneration treatment, heating from room temperature to 450°C at a rate of 5°C / min, and heating at a constant temperature for 30 minutes while introducing nitrogen into the high-temperature furnace; then heating from 450°C to 900°C at a rate of 5°C / min while introducing carbon dioxide into the high-temperature furnace, and heating at a constant temperature for 1 hour;

[0118] S8: Cooling, drying and storing the activated carbon obtained in S7 to obtain modified regenerated activated carbon.

[0119] Example 2

[0120] This embodiment provides a method for modifying and regenerating waste activated carbon, comprising the following steps:

[0121] S1: Take 50g of waste activated carbon from the wet recovery process of waste batteries (the same as in Example 1), soak it in 1500mL of water for 2h, and then filter it to obtain the first cleaning liquid for recycling;

[0122] S2: The activated carbon obtained in S1 is placed in 1000 mL of 0.025 mol / L ethylenediaminetetraacetic acid solution and soaked for 1 hour, then filtered, and the obtained ethylenediaminetetraacetic acid solution containing valuable metals is recovered;

[0123] S3: Soak the activated carbon obtained in step S2 in 1500 mL of water for 1 hour, then filter and separate the solid and liquid, and recycle the second washing liquid;

[0124] S4: The activated carbon obtained in step S3 is placed in 1000 mL of 0.05 mol / L ammonia solution and soaked for 1.5 hours, then filtered, and the obtained ammonia solution is recycled;

[0125] S5: Soak the activated carbon obtained in S4 in 1500 mL of water for 1 h, then filter;

[0126] S6: The activated carbon obtained in S5 was naturally air-dried for 3 h, and the moisture content was 12%;

[0127] S7: The activated carbon obtained in step S6 is mixed with 5% asphalt powder with a D50 particle size of 0.075mm-0.45mm and 7% graphite with a D50 particle size of 0.85mm-4mm, with a mass ratio of asphalt powder to graphite being 1:1.4, and then placed in a high-temperature furnace for heating and regeneration treatment, heating from room temperature to 700°C at a rate of 6°C / min, and heating at a constant temperature for 40min while introducing N2 into the high-temperature furnace; then heating from 700°C to 900°C at a rate of 4°C / min while introducing CO2 into the high-temperature furnace, and heating at a constant temperature for 1.5h;

[0128] S8: Cooling, drying and storing the activated carbon obtained in S7 to obtain modified regenerated activated carbon.

[0129] Example 3

[0130] This embodiment provides a method for modifying and regenerating waste activated carbon, comprising the following steps:

[0131] S1: Take 50g of waste activated carbon from the wet recovery process of waste batteries (the same as in Example 1), soak it in 1500mL of water for 2h, and then filter it to obtain the first cleaning liquid for recycling;

[0132] S2: The activated carbon obtained in S1 is placed in 500 mL of 0.2 mol / L ammonia solution and soaked for 2 h, then filtered, and the obtained first regeneration liquid containing valuable metals is recovered;

[0133] S3: Soak the activated carbon obtained in step S2 in 1500 mL of water for 1 hour, then filter and recover the obtained second cleaning liquid;

[0134] S4: The activated carbon obtained in step S3 is placed in 500 mL of 0.1 mol / L acetic acid solution and soaked for 1.5 hours, then filtered, and the obtained second regeneration liquid is recycled;

[0135] S5: Soak the activated carbon obtained in S4 in 1500 mL of water for 1 h, then filter;

[0136] S6: The activated carbon obtained in S5 was naturally air-dried for 2 h, and the moisture content was 14%;

[0137] S7: The activated carbon obtained in step S6 is mixed with 2% asphalt powder with a D50 particle size of 0.075mm-0.45mm and 5% graphite with a D50 particle size of 0.85mm-4mm, with a mass ratio of asphalt powder to graphite being 1:2.5, and then placed in a high-temperature furnace for heating and regeneration treatment, heating from room temperature to 300°C at a rate of 3°C / min, and heating at a constant temperature for 30 minutes while introducing nitrogen into the high-temperature furnace; then heating from 300°C to 800°C at a rate of 6°C / min while introducing carbon dioxide into the high-temperature furnace, and heating at a constant temperature for 1 hour;

[0138] S8: Cooling, drying and storing the activated carbon obtained in S7 to obtain modified regenerated activated carbon.

[0139] Example 4

[0140] The difference between this embodiment and embodiment 1 is that the asphalt powder and graphite are omitted in step S7, and the remaining parameters are exactly the same as those in embodiment 1.

[0141] Example 5

[0142] The difference between this embodiment and embodiment 1 is that in step S7, the asphalt powder and other materials are replaced by graphite, and the remaining parameters are exactly the same as those in embodiment 1.

[0143] Example 6

[0144] The difference between this embodiment and embodiment 1 is that in step S7, the graphite and other materials are replaced by asphalt powder, and the other parameters are exactly the same as those in embodiment 1.

[0145] Example 7

[0146] The difference between this embodiment and embodiment 1 is that in step S7, the mass fraction of the asphalt powder is adjusted to 8%, so that the mass ratio of the asphalt powder to graphite is adjusted to 1:0.625, and the remaining parameters are exactly the same as those in embodiment 1.

[0147] Example 8

[0148] The difference between this embodiment and embodiment 1 is that in step S7, the mass fraction of asphalt powder is adjusted to 1%, and the mass fraction of graphite is adjusted to 7%, so that the mass ratio of asphalt powder and graphite is adjusted to 1:7, and the remaining parameters are exactly the same as those in embodiment 1.

[0149] Example 9

[0150] This embodiment provides a method for modifying and regenerating waste activated carbon, comprising the following steps:

[0151] S1: Take 50g of waste activated carbon from the wet recycling process of waste batteries, soak it in 1000mL of water for 2h, and then filter the obtained first washing liquid for recycling;

[0152] S2: The activated carbon obtained in S1 is placed in 500 mL of 0.025 mol / L citric acid solution and soaked for 1 hour, then filtered, and the obtained citric acid solution containing the valuable metals is recovered;

[0153] S3: Soak the activated carbon obtained in step S2 in 1000 mL of water for 1 hour, then filter and recover the obtained second cleaning liquid;

[0154] S4: Soak the activated carbon obtained in step S3 in 500 mL of 0.025 mol / L citric acid solution for 2 h, then filter and recycle the obtained ammonia water;

[0155] S5: Soak the activated carbon obtained in S4 in 1000 mL of water for 1 h, then filter;

[0156] S6: The activated carbon obtained in S5 was naturally air-dried for 2 h, and the moisture content was 14%;

[0157] S7: The activated carbon obtained in step S6 is mixed with 3% asphalt powder with a D50 particle size of 0.075mm-0.45mm and 5% graphite with a D50 particle size of 0.85mm-4mm, with a mass ratio of asphalt powder to graphite being 1:1.7, and then placed in a high-temperature furnace for heating, modification and regeneration treatment, heating from room temperature to 450°C at a rate of 5°C / min, and heating at a constant temperature for 30 minutes while introducing nitrogen into the high-temperature furnace; then heating from 450°C to 900°C at a rate of 5°C / min while introducing carbon dioxide into the high-temperature furnace, and heating at a constant temperature for 1 hour;

[0158] S8: Cooling, drying and storing the activated carbon obtained in S7 to obtain modified regenerated activated carbon.

[0159] Comparative Example 1

[0160] The difference between this comparative example and Example 1 is that steps S2 and S3 are omitted, and step S4 is replaced by "immersing the activated carbon obtained in S1 in 500 mL of 0.05 mol / L hydrochloric acid solution for 1 hour, then filtering, and recovering the obtained regenerated liquid containing valuable metals", and at the same time, asphalt powder and graphite are omitted, and the remaining parameters are exactly the same as in Example 1.

[0161] Figures 2 and 3 are SEM images of the modified regenerated activated carbon prepared in Example 1 and Comparative Example 1, respectively. From the comparison of Figures 2 and 3, it can be seen that the number of micropores of the modified regenerated activated carbon prepared in the present application is significantly greater than that of the regenerated activated carbon treated with hydrochloric acid. This indicates that the method of the present application effectively desorbs the substances in the micropores of the waste carbon. Compared with the regenerated activated carbon treated with hydrochloric acid, the modified regenerated activated carbon prepared in the present application has more micropores, larger micropore diameters, incompletely transparent pores, rough inner walls, and a larger specific surface area of ​​the activated carbon. This indicates that the method of the present application not only effectively desorbs the substances in the micropores, but also obtains good modification.

[0162] Comparative Example 2

[0163] The difference between this comparative example and Example 1 is that steps S2 and S3 are omitted, and step S4 is replaced by "immersing the activated carbon obtained in S1 in 500 mL of 0.05 mol / L hydrochloric acid solution for 1 h, then filtering, and recovering the obtained regenerated liquid containing valuable metals." The remaining parameters are exactly the same as those in Example 1.

[0164] The untreated waste activated carbon in Example 1, and the modified regenerated activated carbons of Examples 1-9 and Comparative Examples 1-2 were tested, including:

[0165] (1) Iodine adsorption value test

[0166] The test was carried out with reference to the national standard "GBT 12496.8-2015 Test method for wood activated carbon - Determination of iodine adsorption value".

[0167] (2) Valuable metal element content test

[0168] The sample pre-treatment was carried out according to the operating procedures of the national standard "GBT 12496.19-2015 Test method for wood activated carbon - Determination of iron content". After the volume was adjusted to 100 mL, the content of valuable metal elements in the solution was detected by inductively coupled plasma spectrometry (ICP).

[0169] (3) Ash content test

[0170] The test was carried out with reference to the national standard "GBT12496.3-1999 Determination of ash content of wood activated carbon".

[0171] The test results are shown in Table 1.

[0172] Table 1

[0173] analyze:

[0174] It can be seen from the results of Examples 1-3 that the iodine adsorption value of the modified regenerated activated carbon of the present application can reach more than 800 mg / g, reflecting its good regeneration performance, and the content of valuable metal elements and ash is low, indicating that the method of the present application can not only effectively regenerate waste activated carbon, but also recover valuable metals and reduce the ash content.

[0175] The results of Examples 1 and 4-6 demonstrate that pitch powder and graphite work synergistically during the heat-modification regeneration step to replenish carbon loss, increase the specific surface area of ​​the activated carbon, enhance the iodine adsorption value of the activated carbon, and increase the yield of activated carbon. Omitting either pitch powder or graphite, or adding only one of them, results in a relatively low iodine adsorption value and relatively high metal and ash contents.

[0176] It can be seen from the results of Example 1 and Examples 7-8 that if the mass ratio of asphalt powder and graphite is too small or too large, it will lead to insufficient conversion and utilization of carbon materials, waste of resources, low carbon loss replenishment rate, introduction of new impurities, easy clogging of pores, relatively low iodine adsorption value, and relatively high ash content.

[0177] The results of Example 1 and Comparative Examples 1-2 indicate that, compared to Example 1, Comparative Example 1 adds the same theoretical amount of hydrochloric acid (0.48 times the theoretical amount) as a chemical modification solution, but does not perform the chemical complexation step and omits the asphalt powder and graphite. This results in a relatively low iodine adsorption value for the regenerated activated carbon and a relatively high ash content. Compared to Comparative Example 1, although Comparative Example 2 adds asphalt powder and graphite for thermal modification and regeneration, the improvement in the regeneration performance of the activated carbon is limited.

[0178] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for modifying and regenerating waste activated carbon, comprising: The waste activated carbon is subjected to chemical complexation, chemical modification and heating modification regeneration in sequence to obtain modified regenerated activated carbon.

2. The method for modifying and regenerating waste activated carbon according to claim 1, wherein: The waste activated carbon includes waste activated carbon generated in the process of wet recycling of waste batteries.

3. The method for modifying and regenerating waste activated carbon according to claim 1 or 2, wherein: The waste activated carbon includes valuable metal elements and / or ash.

4. The method for modifying and regenerating waste activated carbon according to claim 3, wherein: The valuable metal elements in the waste activated carbon include at least one of Ni, Co and Mn elements.

5. The method for modifying and regenerating waste activated carbon according to claim 3 or 4, wherein: Taking the total mass of the waste activated carbon as 100%, the mass fraction of the valuable metal element is 0.5-3%; Preferably, based on the total mass of the waste activated carbon being 100%, the mass fraction of the ash is 8-12%.

6. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 5, wherein: The iodine adsorption value of the waste activated carbon is 90-200 mg / g.

7. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 6, wherein: Prior to the chemical complexation, the waste activated carbon is subjected to a physical cleaning process; Preferably, the physical cleaning method comprises a first water immersion; Preferably, during the first water immersion process, the mass ratio of the waste activated carbon to water is 1:(10-50); Preferably, the physical cleaning period lasts for 1-3 hours.

8. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 7, wherein: The specific steps of the chemical complexation include: soaking the waste activated carbon in a chemical complexation liquid; Preferably, the chemical complexing liquid includes ammonia, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid and at least one of fruit acids; Preferably, the amount of the chemical complexing liquid added is 0.2-1 times the theoretical amount required to complex the valuable metal elements in the waste activated carbon; Preferably, the mass ratio of the waste activated carbon to the chemical complexing liquid is 1:(10-50); Preferably, the chemical complexation time is 1-3 hours.

9. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 8, wherein: Before the chemical modification, the waste activated carbon after chemical complexation is subjected to two-stage physical cleaning; Preferably, the two-stage physical cleaning method includes a second water immersion; Preferably, during the second water immersion process, the mass ratio of the waste activated carbon to water is 1:(10-50); Preferably, the duration of the second stage physical cleaning is 1-3 hours.

10. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 9, wherein: The specific steps of the chemical modification include: soaking the chemically complexed waste activated carbon in a chemical modification liquid; Preferably, the chemical modification liquid comprises at least one of ammonia water, citric acid, ethylenediaminetetraacetic acid, acetic acid, formic acid and fruit acid; Preferably, the concentration of the chemical modification liquid is 0.02-0.2 mol / L; Preferably, the mass ratio of the waste activated carbon after chemical complexation to the chemically modified liquid is 1:(10-50); Preferably, the chemical modification time is 1-3 hours.

11. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 10, wherein: Before the heating modification and regeneration, the chemically modified waste activated carbon is subjected to three-stage physical cleaning and physical drying in sequence; Preferably, the three-stage physical cleaning method includes a third water immersion; Preferably, during the third water immersion process, the mass ratio of the waste activated carbon to water is 1:(10-50); Preferably, the time of the three stages of physical cleaning is 1-3 hours; Preferably, the moisture content of the waste activated carbon obtained after the physical drying is less than or equal to 15%.

12. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 11, wherein: The specific steps of the heating modification and regeneration include: mixing the chemically modified waste activated carbon with the carbon material and performing heating regeneration; Preferably, the carbon material comprises pitch powder and graphite; Preferably, the D50 particle size of the asphalt powder is 0.075-0.45 mm; Preferably, the D50 particle size of the graphite is 0.85-4 mm; Preferably, the mass ratio of the asphalt powder to graphite is 1:(1-3); Preferably, based on the mass of the chemically modified waste activated carbon being 100%, the mass fraction of the asphalt powder is 1-8%; Preferably, based on the mass of the chemically modified waste activated carbon being 100%, the mass fraction of the graphite is 1-8%; Preferably, the heating regeneration is segmented heating regeneration, and the segmented heating regeneration includes: first performing a first stage heating regeneration, and then performing a second stage heating regeneration; Preferably, the temperature of the first stage heating regeneration is 300-700°C; Preferably, the atmosphere of the first stage heating regeneration is an inert atmosphere, and the gas in the inert atmosphere includes N2; Preferably, the temperature of the second stage heating regeneration is 800-1000°C; Preferably, the gas in the atmosphere of the second stage heating and regeneration includes CO2; Preferably, the heating rate of the first stage heating regeneration and the heating rate of the second stage heating regeneration are independently 2-8°C / min; Preferably, the heating regeneration time is 20-90 min.

13. The method for modifying and regenerating waste activated carbon according to any one of claims 1 to 12, comprising: S1, a physical cleaning stage: soaking the waste activated carbon in water for 1-3 hours, and then performing solid-liquid separation, wherein the waste activated carbon includes waste activated carbon generated in the process of wet recovery of waste batteries; S2, chemical complexation: soaking the waste activated carbon obtained after solid-liquid separation in step S1 in a chemical complexation liquid for 1-3 hours, and then performing solid-liquid separation; S3, second stage physical cleaning: the waste activated carbon obtained after solid-liquid separation in step S2 is subjected to a second water immersion for 1-3 hours, and then solid-liquid separation is performed; S4, chemical modification: soaking the waste activated carbon obtained after solid-liquid separation in step S3 in a chemical modification liquid for 1-3 hours, and then performing solid-liquid separation; S5, three-stage physical cleaning: the waste activated carbon obtained after solid-liquid separation in step S4 is subjected to a third water immersion for 1-3 hours, and then solid-liquid separation is performed; S6, physical drying: air-drying the waste activated carbon obtained after solid-liquid separation in step S5 until the moisture content of the waste activated carbon is less than or equal to 15%; S7, heating modification and regeneration: the waste activated carbon after air drying in step S6 is mixed with asphalt powder and graphite, and heated and regenerated in stages to obtain modified regenerated activated carbon.

14. A modified regenerated activated carbon, wherein: The modified regenerated activated carbon is prepared by the method for modifying and regenerating waste activated carbon according to any one of claims 1 to 9.

15. The modified regenerated activated carbon according to claim 14, wherein: The modified regenerated activated carbon includes valuable metal elements and / or ash; Preferably, the valuable metal element in the modified regenerated activated carbon includes at least one of Ni, Co and Mn elements; Preferably, based on the total mass of the modified regenerated activated carbon being 100%, the mass fraction of the valuable metal element is less than or equal to 0.2%; Preferably, based on the total mass of the modified regenerated activated carbon being 100%, the mass fraction of the ash is less than or equal to 5%; Preferably, the iodine adsorption value of the modified regenerated activated carbon is greater than or equal to 800 mg / g.

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