A method for efficiently removing zinc, sulfur and silicon from waste tire pyrolysis carbon black by microwave heat treatment combined with high-pressure alkaline water heat treatment and recovering zinc

Abstract

The present invention discloses a method for efficiently dezincifying, desulfurizing, and desiliconizing waste tire pyrolysis carbon black by combining microwave heat treatment with high-pressure alkaline water heat treatment, and recovering zinc. The method belongs to the field of waste treatment and resource utilization technology. The method comprises the following steps: subjecting waste tire pyrolysis carbon black to microwave heat treatment to obtain solid carbon black and volatile condensate, collecting the volatile condensate to obtain zinc and its compounds; mixing the solid carbon black with alkaline solution and subjecting it to high-pressure hydrothermal treatment, followed by water washing to obtain purified carbon black and a washing liquid; adding lime to the washing liquid to obtain calcium silicate and alkaline solution; recovering the calcium silicate and recycling the alkaline solution. This method significantly increases the efficiency of zinc, sulfur, and silicon removal, shortens process time, and reduces raw material and equipment costs, providing a new approach for the resource utilization of waste tire pyrolysis carbon black and possessing high application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste treatment and resource utilization, and more specifically relates to a method for efficiently dezincifying, desulfurizing, and desiliconizing waste tire cracking carbon black and recovering zinc by microwave heat treatment combined with high-pressure alkaline water heat treatment. Background Art

[0002] With the continuous development of the automotive industry, the number of waste tires has increased dramatically. Therefore, how to achieve the recycling and utilization of waste tire resources is of great significance to the sustainable development of circular economy, industrial ecology and society.

[0003] Currently, there are four main methods for recycling scrap tires: tire retreading, rubber crumb, reclaimed rubber, and thermal cracking. Pyrolysis carbon black is a key product of scrap tire pyrolysis. After further processing, it can be used as tire reinforcement carbon black, pigment, and other materials. Recycling pyrolysis carbon black is of great significance for energy conservation and environmental protection, as well as scrap tire recycling. Various chemical additives, such as ZnO, SiO2, and sulfur, are often added during tire production. These additives accumulate in the pyrolysis carbon black as the scrap tires pyrolyze and produce ash. Ash covers the active sites on the pyrolysis carbon black surface, hindering direct contact between the pyrolysis carbon black and rubber molecular chains, significantly reducing the reinforcing effect of the pyrolysis carbon black. Zinc, sulfur, and silicon dominate the ash content. Furthermore, recovering the zinc from the pyrolysis carbon black of scrap tires offers significant economic benefits. Therefore, the removal and recovery of zinc, sulfur, and silicon from the pyrolysis carbon black of scrap tires has become a hot topic of research.

[0004] Carbon black purification methods generally include physical and chemical methods. However, the purification efficiency and effect of physical methods are low, and they are usually combined with chemical leaching processes. Therefore, at present, chemical methods are mostly used for desulfurization and ash reduction of carbon black. That is, acid, alkali, or a combination of acid and alkali are used to obtain purer carbon black. The existing acid method and acid-base combined method have complex treatment processes and poor treatment effects, and cannot achieve efficient recovery of removed zinc and sulfur. In addition, the large-scale use of acid and alkali will also have an impact on the environment, and the cost of post-treatment of the waste acid and waste alkali generated is high, which hinders its commercial development. Although the acid treatment and acid-base combined treatment of waste tire pyrolysis carbon black have been successfully verified on a laboratory scale, in order to achieve industrial treatment on a larger scale, it is still necessary to develop a more environmentally friendly, economical and recyclable method. At the same time, the recovery and utilization of zinc and sulfur removed from waste tire pyrolysis carbon black remains an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for efficiently dezincifying, desulfurizing, desiliconizing and recovering zinc from waste tire pyrolysis carbon black by combining microwave heat treatment with high-pressure alkaline water heat treatment, so as to solve the problems existing in the above-mentioned prior art, provide a more economical and environmentally friendly method for treating waste tire pyrolysis carbon black, and at the same time achieve efficient recovery of zinc and sulfur removed from waste tire pyrolysis carbon black.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for efficiently dezincifying, desulfurizing and desiliconizing waste tire pyrolysis carbon black and recovering zinc by combining microwave heat treatment with high-pressure alkaline water heat treatment, comprising the following steps:

[0008] The waste tire pyrolysis carbon black is subjected to microwave heat treatment to obtain solid carbon black and volatile condensate, and the volatile condensate is collected to obtain zinc and its compounds;

[0009] Solid carbon black and alkali solution are mixed and subjected to high-pressure hydrothermal treatment, and then washed with water to obtain purified carbon black and a washing liquid; lime is added to the washing liquid to obtain calcium silicate and alkali solution; the calcium silicate is recovered and the alkali solution is recycled.

[0010] The present invention utilizes a combined microwave heat treatment and high-pressure alkaline water heat treatment method to treat waste tire pyrolysis carbon black, achieving efficient dezincification, desulfurization, and desiliconization, and recovering zinc and its compounds. This method fully utilizes the uniform heating, rapid heating rate, and high heating efficiency of microwave heat treatment, reaching the desired temperature in a short period of time, rapidly removing zinc and sulfur, and recovering them. This method can remove 99.94% of zinc and 89.82% of sulfur. Simultaneously, high-pressure alkaline water heat treatment using alkaline solution can remove 99.99% of silicon, and the carbon black forms a more compact structure, facilitating subsequent adjustment of the carbon black pore structure. This addresses the poor treatment effectiveness of conventional waste tire pyrolysis carbon black treatment methods. Furthermore, the present invention can efficiently remove zinc, sulfur, and silicon in separate steps, and effectively recover zinc and its compounds (Zn, ZnS, and ZnO) and silicon, resolving the problem of simultaneous removal of zinc, sulfur, and silicon, which prevents effective recovery of zinc and sulfur.

[0011] The processing steps of the present invention include microwave heat treatment and high-pressure alkaline water heat treatment, the method is simple, and the processing process is more economical and environmentally friendly.

[0012] The reaction mechanism of the method of the present invention is as follows: microwave heat treatment is used to enable the reaction system to quickly reach the required temperature, thereby achieving efficient removal of zinc and its compounds (the zinc removal rate reaches 99.94%, and the sulfur removal rate reaches 90.05%), and avoiding the removal of silicon; high-pressure alkaline water heat treatment is used to enable the alkali and silicon dioxide in the system to react more fully and quickly, achieving efficient removal of silicon (the silicon removal rate reaches 99.99%), and at the same time, the entire reaction system can be placed under a certain pressure, thereby improving the densification of the carbon black structure.

[0013] Preferably, the microwave power of the microwave heat treatment is 1-3 kW, the microwave frequency of the microwave heat treatment is 2400-1500 MHz, the temperature of the microwave heat treatment is 900-1100° C., and the holding time of the microwave heat treatment is 30-60 min.

[0014] Preferably, the microwave heat treatment is carried out in an inert gas, which includes nitrogen or argon, and the flow rate of the inert gas is 0.4 to 1 L / min. The flowing inert gas can ensure that the microwave heat treatment is carried out in an oxygen-free state to prevent high-temperature combustion of carbon, and at the same time, the flow of the inert gas can also carry away volatile condensate zinc and its compounds, thereby achieving effective recovery of zinc and its compounds.

[0015] Preferably, the zinc and its compounds include Zn, ZnS and ZnO.

[0016] Preferably, the microwave heat treatment process further includes the step of collecting and treating tail gas; the reagents used in the tail gas treatment step include but are not limited to sodium hydroxide; the step of collecting and treating tail gas absorbs the tail gas that may be generated.

[0017] Preferably, the alkali solution includes sodium hydroxide and / or potassium hydroxide, and the concentration of the alkali solution is 3-5M.

[0018] Preferably, the ratio of the waste tire pyrolysis carbon black to the alkali solution is 1 g: 10-40 mL; the high-pressure hydrothermal treatment is carried out in a closed container, the pressure of the high-pressure hydrothermal treatment is 2-3 MPa, the temperature of the high-pressure hydrothermal treatment is 120-150° C., and the time of the high-pressure hydrothermal treatment is 12-18 h.

[0019] Preferably, the step of drying the solid product is further included after the water washing.

[0020] Preferably, the water washing is ultrasonic water washing, the ultrasonic power of the ultrasonic water washing is 50-200W, the temperature of the ultrasonic water washing is 25-30°C, and the ultrasonic water washing is stopped after the product obtained by the high-pressure hydrothermal treatment is neutral.

[0021] Preferably, the drying temperature is 100-120° C., and the drying time is 10-12 hours.

[0022] Preferably, the addition of lime to the water washing liquid is stopped when no more precipitation is generated; and the water washing liquid is a silicate-containing alkaline solution.

[0023] The present invention discloses the following technical effects:

[0024] 1. The present invention uses a method combining microwave heat treatment and high-pressure alkaline water heat treatment to treat waste tire pyrolysis carbon black, achieving efficient dezincification, desulfurization, and desiliconization, and recovering zinc and its compounds. This method fully utilizes the characteristics of microwave heat treatment, such as uniform heating, fast heating rate, and high heating efficiency, to reach the required temperature in a short time, quickly remove zinc and sulfur, and recover them. Using this method, 99.94% of zinc and 90.05% of sulfur can be removed. At the same time, high-pressure alkaline water heat treatment with alkaline solution can remove 99.99% of silicon and make the carbon black form a denser structure, which is conducive to the subsequent adjustment of the carbon black pore structure.

[0025] 2. The method of the present invention can quickly remove zinc and sulfur from waste tire pyrolysis carbon black, directly recover zinc without further treatment, and does not produce waste acid, thus solving the problem of existing treatment methods that generate a large amount of waste acid, increase subsequent treatment steps, and have an impact on the environment.

[0026] 3. The method of the present invention significantly increases the efficiency of zinc, sulfur and silicon removal, shortens the process time, reduces the cost of raw materials and equipment, and provides a new way for the resource utilization of waste tire pyrolysis carbon black, which has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0028] Figure 1 is a process flow chart of the method of the present invention;

[0029] Figure 2 The XRD patterns of waste tire pyrolysis carbon black used in the examples and comparative examples are as follows;

[0030] Figure 3 This is the XRD pattern of the volatile condensate produced in Example 1;

[0031] Figure 4 These are the XRD patterns of the purified carbon black obtained in Examples 1 to 3 and Comparative Examples 1, 2, 3, and 6. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The contents of zinc, sulfur and silicon in the waste tire pyrolysis carbon black used in the following examples and comparative examples are: zinc content is 100.95 kg / t, sulfur content is 17.99 kg / t, and silicon content is 11.56 kg / t; the XRD pattern of the waste tire pyrolysis carbon black used is as follows: Figure 2 shown.

[0038] All other raw materials used are commercially available products unless otherwise specified.

[0039] The room temperature involved in the present invention is 25±5°C unless otherwise specified.

[0040] Example 1

[0041] This embodiment provides a method for treating waste tire pyrolysis carbon black by combining microwave heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0042] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a microwave tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 900 °C at a microwave power of 3000 W and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0043] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 25°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0044] The XRD pattern of the volatile condensate recovered in this embodiment is as follows: Figure 3 As shown. Figure 3 It can be seen that the recovered volatile condensate includes Zn, ZnS and ZnO, realizing the recovery of zinc and sulfur.

[0045] Example 2

[0046] This embodiment provides a method for treating waste tire pyrolysis carbon black by combining microwave heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0047] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a microwave tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 1000 °C at a microwave power of 3000 W and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0048] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 30°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0049] Example 3

[0050] This embodiment provides a method for treating waste tire pyrolysis carbon black by combining microwave heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0051] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a microwave tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 1100 °C at a microwave power of 3000 W and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0052] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 30°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0053] Example 4

[0054] This embodiment provides a method for treating waste tire pyrolysis carbon black by combining microwave heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0055] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a microwave tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 1100 °C at a microwave power of 2000 W and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0056] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 30°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0057] Example 5

[0058] This embodiment provides a method for treating waste tire pyrolysis carbon black by combining microwave heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0059] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a microwave tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 1100 °C at a microwave power of 1500 W and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0060] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 30°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0061] Comparative Example 1

[0062] This comparative example provides a method for treating waste tire pyrolysis carbon black by combining conventional heating heat treatment and high-pressure alkaline water heat treatment. The specific steps are as follows:

[0063] (1) 10 g of waste tire pyrolysis carbon black was placed in a corundum crucible and then placed in a conventional tube furnace. Nitrogen was introduced at a flow rate of 1 L / min. The nitrogen was continuously introduced during the whole process. The crucible was heated to 1000 °C at a heating rate of 10 °C / min and kept warm for 30 min. After cooling to room temperature, the solid carbon black was taken out and the volatile condensate was collected to obtain solid carbon black and recovered zinc and its compounds (including Zn, ZnS and ZnO). The tail gas generated during the reaction was collected using sodium hydroxide.

[0064] (2) The solid carbon black obtained in step (1) is mixed with 100 mL of 5M NaOH solution, stirred at 30°C at a speed of 30 r / min for 10 minutes, and then transferred to a high-pressure reactor and kept at 120°C for 12 hours. After cooling to room temperature, the solid carbon black is washed with deionized water at 30°C and an ultrasonic power of 200 W until the washing liquid is neutral, filtered, and the solid product is dried at 100°C for 12 hours to obtain purified carbon black; lime is added to the washing liquid until no more precipitation is generated, thereby obtaining calcium silicate and alkali solution, the calcium silicate is recovered, and the alkali solution is recycled.

[0065] Comparative Example 2

[0066] The difference from Comparative Example 1 is that the heating temperature in the conventional tube furnace is replaced by 1000° C. to 1100° C., and the rest is the same as Comparative Example 1.

[0067] Comparative Example 3

[0068] The difference from Comparative Example 1 is that the heating temperature in the conventional tube furnace is replaced by 1000° C. to 1200° C., and the rest is the same as Comparative Example 1.

[0069] Comparative Example 4

[0070] The difference from Comparative Example 3 is that the holding time for treatment in a conventional tube furnace is replaced from "30 min" to "1 h", and the rest is the same as Comparative Example 3.

[0071] Comparative Example 5

[0072] The difference from Comparative Example 3 is that the "high-pressure reactor" in step (2) is replaced by a "beaker", that is, the reaction conditions are replaced by high-pressure hydrothermal to normal-pressure hydrothermal, and the rest are the same as Comparative Example 3.

[0073] Comparative Example 6

[0074] The difference from Comparative Example 1 is that the heating temperature in the conventional tube furnace is replaced from "1000° C." to "1400° C.", and the rest is the same as Comparative Example 1.

[0075] Comparative Example 7

[0076] The difference from Comparative Example 6 is that the holding time in the conventional tube furnace is replaced from "30 min" to "1 h", and the rest is the same as Comparative Example 6.

[0077] Figure 4 The XRD patterns of the solid carbon black obtained in Examples 1 to 3 and Comparative Examples 1, 2, 3 and 6 are shown in FIG. Figure 4 It can be seen that the XRD pattern of the solid carbon black treated by the method of the present invention mainly includes peaks of CaS, S and SiO2, while the XRD patterns of the solid carbon black obtained by the methods described in Comparative Examples 1, 2, 3 and 6 show, in addition to the peaks of CaS, S and SiO2, a ZnS peak also appears, which proves that the method of the present invention can achieve effective removal of zinc compounds. When the microwave process is omitted, the solid carbon black still includes zinc compounds and the removal of zinc compounds cannot be achieved.

[0078] Effect verification:

[0079] The removal rates of zinc, sulfur and silicon, the recovery rates of carbon black and the recovery rates of zinc, sulfur and silicon in Examples 1 to 5 and Comparative Examples 1 to 7 were measured:

[0080] Determination method: The zinc and sulfur contents of the carbon black obtained in Examples 1 to 5 and Comparative Examples 1 to 7 were quantitatively analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the zinc and sulfur removal rates were calculated by formula (1), and the silicon removal rate was calculated by formula (2).

[0081]

[0082] In formula (1), μ is the zinc or sulfur release rate; when μ is the zinc release rate, M1 is the initial zinc content in the waste tire pyrolysis carbon black, and M2 is the zinc content in the solid carbon black; when μ is the sulfur release rate, M1 is the initial sulfur content in the waste tire pyrolysis carbon black, and M2 is the sulfur content in the solid carbon black.

[0083] In formula (2), μ1 is the silicon removal rate, M3 is the initial silicon content in the waste tire pyrolysis carbon black, and M4 is the silicon content in the purified carbon black.

[0084] The measurement results are shown in Table 1.

[0085] Table 1 Test results of zinc, sulfur and silicon removal rates in Examples 1 to 5 and Comparative Examples 1 to 7

[0086]

[0087]

[0088] Comparing the data of Example 3 and Comparative Example 1 in Table 1, it can be seen that when only the heating method is changed, the dezincification rate increases from 99.69% to 99.94%, and the desulfurization rate increases from 47.30% to 90.05%.

[0089] Comparing the data of Example 3 with Comparative Examples 2-4 and Comparative Examples 6-7 in Table 1, it can be seen that conventional heating requires heating at 1400°C for 1 hour to significantly improve the zinc removal rate, but the sulfur removal rate is still relatively low, reaching only 68.64%. In addition, compared with conventional heating methods, the present invention can significantly improve the recovery rates of carbon black, zinc, sulfur, and silicon at lower temperatures and shorter holding times.

[0090] Comparing the data of Example 3 and Comparative Examples 3 and 5 in Table 1, it can be seen that the removal of silicon can be basically achieved by using a high-temperature reactor, with a removal rate of 99.99%. This is because the high-pressure condition promotes the desiliconization reaction.

[0091] From Table 1 and Figure 3 It can be seen that the method of the present invention can achieve efficient removal of zinc, sulfur and silicon. On the basis of ensuring high carbon black yield and silicon recovery rate, the recovery rate of zinc and sulfur is significantly improved. At the same time, zinc can be directly recovered and utilized in the form of ZnS, ZnO and Zn.

[0092] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0093] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for efficiently dezincifying, desulfurizing, and desiliconizing waste tire pyrolysis carbon black by microwave heat treatment combined with high-pressure alkaline water heat treatment and recovering zinc, characterized in that: The steps include: The waste tire pyrolysis carbon black is subjected to microwave heat treatment to obtain solid carbon black and volatile condensate, and the volatile condensate is collected to obtain zinc and its compounds; The solid carbon black and alkali solution are mixed and subjected to high-pressure hydrothermal treatment, and then washed with water to obtain purified carbon black and a washing liquid; Adding lime to the water wash to obtain calcium silicate and alkali solution; recovering the calcium silicate and recycling the alkali solution; The microwave power of the microwave heat treatment is 1-3 kW, the microwave frequency of the microwave heat treatment is 2400-1500 MHz, the temperature of the microwave heat treatment is 900-1100° C., and the holding time of the microwave heat treatment is 30-60 min; The microwave heat treatment is carried out in an inert gas, wherein the inert gas includes nitrogen or argon, and the flow rate of the inert gas is 0.4-1 L / min; The zinc and its compounds include Zn, ZnS and ZnO; The ratio of the waste tire pyrolysis carbon black to the alkali solution is 1g:10-40mL; the pressure of the high-pressure hydrothermal treatment is 2-3MPa, the temperature of the high-pressure hydrothermal treatment is 120-150°C, and the time of the high-pressure hydrothermal treatment is 12-18h; The addition of the lime to the water wash solution is stopped when no precipitation is generated.

2. The method according to claim 1, characterized in that The microwave heat treatment process also includes the steps of collecting and treating tail gas.

3. The method according to claim 1, characterized in that The alkali solution includes sodium hydroxide and / or potassium hydroxide, and the concentration of the alkali solution is 3-5M.

4. The method according to claim 1, wherein After the water washing, the method further comprises the step of drying the solid product.

5. The method according to claim 4, characterized in that The water washing is ultrasonic water washing, the ultrasonic power of the ultrasonic water washing is 50-200W, the temperature of the ultrasonic water washing is 25-30°C, and the ultrasonic water washing is stopped after the product obtained by the high-pressure hydrothermal treatment is neutral; and / or, the temperature of the drying is 100-120°C, and the drying time is 10-12 hours.

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