Methods and applications for preparing magnetic mercury removal adsorbents from waste plastics and waste battery tailings

Abstract

This invention discloses a method for preparing a magnetic mercury removal adsorbent using waste plastics and waste battery tailings, and its application. The method includes the following steps: S1, premixing treatment: mixing waste battery tailings and waste plastic particles at a mass ratio of 1:0.17-1; S2, pyrolysis reaction: raising the tubular furnace to the target temperature of 500-700℃ and maintaining the temperature for 6 hours; S3, post-treatment. The application is the removal of gaseous mercury from flue gas using the magnetic mercury removal adsorbent. This invention uses waste battery acid extraction tailings and waste plastics as precursors, employing a simple pyrolysis reaction to synthesize a magnetic mercury removal adsorbent. The raw materials are readily available and inexpensive, the preparation method is simple, and it is easy to achieve industrial-scale application. The prepared magnetic mercury removal adsorbent possesses many advantages such as high mercury removal efficiency, strong acid and water resistance, magnetic recovery capability, and high-temperature regeneration capability, providing a new preparation method for magnetic recyclable flue gas mercury removal adsorbents.

Description

TECHNICAL FIELD

[0001] The application relates to a method for preparing a magnetic mercury-removal adsorbent from waste plastics and waste battery tailings and application thereof. BACKGROUND

[0002] According to the atmospheric pollutant emission inventory, non-ferrous metal smelting and fossil fuel thermal power generation are one of the main anthropogenic mercury emission sources. Generally speaking, oxidized mercury (Hg 2+ ) and particulate mercury (Hg p ) in smelting flue gas can be effectively removed by tail flue gas pollutant control devices and particulate control devices, while elemental mercury (Hg 0 ) is often difficult to capture due to its high chemical stability, strong volatility and low solubility. Therefore, developing efficient, environmentally friendly and recyclable mercury-removal adsorbents has become a key task for controlling flue gas mercury emissions.

[0003] Up to now, a large number of mercury-removal adsorbents have been developed, such as activated carbon, fly ash, noble metals, metal oxides, metal sulfides, etc. From the practicality and engineering point of view, the activated carbon injection technology is a relatively mature adsorbent mercury removal method, but it is limited by the high cost of commercial activated carbon, poor recycling performance and secondary pollution, and has not been popularized in industry. Based on this, how to develop efficient, low-cost and recyclable mercury-removal adsorbents has become a bottleneck problem for solving the current flue gas injection mercury removal technology. Researchers have focused on easily accessible and low-cost materials, such as solid waste-based materials (magnetic beads extracted from fly ash, biomass coke, petroleum coke, fly ash-based materials, etc.), natural minerals, waste plastics, etc. The above work has brought enlightenment to the development of new mercury-removal adsorbents: (1) from the cost and resource utilization point of view, as much as possible, choose environmentally friendly and large industrial waste to serve as the substrate of the mercury-removal adsorbent, which can greatly reduce the cost and also realize high-value utilization of resources; (2) from the perspective of recycling and renewable, magnetic separation technology makes it possible to regenerate and recycle the mercury-removal adsorbent, and the key is how to realize the low-cost and simple magnetic recovery of the adsorbent; (3) from the industrial application and popularization point of view, the preparation method of the adsorbent is simple and convenient for large-scale production. Based on the above perspectives, waste battery acid extraction residues and waste plastics can be used as potential and excellent mercury-removal adsorbent preparation substrates.

[0004] In the past decade, with the popularity of portable electronic devices and electric vehicles, the lithium battery industry has experienced explosive growth. At the same time, the scrap window period of waste lithium batteries has also been introduced, and the recycling of waste lithium batteries has been industrialized, mainly in three ways: wet recovery, fire recovery, and combination of wet and fire methods. The properties of waste battery residues extracted by wet recovery are relatively stable, and the waste residues after acid extraction still contain a small amount of Ni, Co and a large amount of Ca, Fe, which mainly exist in the form of sulfate. How to reasonably utilize the above acid-extracted waste residue is a problem that needs to be solved at present. SUMMARY

[0005] In view of the above problems, the present application provides a method for preparing a magnetic mercury removal adsorbent from waste plastics and waste battery tailings, and application thereof.

[0006] The technical scheme of the present application is:

[0007] The method for preparing a magnetic mercury removal adsorbent from waste plastics and waste battery tailings comprises the following steps:

[0008] S1, premixing treatment: crushing and grinding the waste plastics, then passing them through a 200-mesh screen to obtain waste plastic particles, and mixing and stirring the waste battery tailings after passing through a 200-mesh screen with the waste plastic particles at a mass ratio of 1:0.17~1 to obtain a mixed powder;

[0009] S2, pyrolysis reaction: 10g of the mixed powder is taken in a quartz boat and placed in a tube furnace, the furnace is pre-purged at room temperature with N2, the N2 flow rate is set to 1~1.5L / min, after purging for 5min, the tube furnace is raised to the target temperature of 500~700℃ at a heating rate of 7~10℃ / min, and the temperature is kept constant for 6h of pyrolysis reaction;

[0010] S3, post-treatment: after the pyrolysis reaction is completed, stop heating, maintain N2 purging for 0.5~1.5h, then close the N2 purging and close the inlet / outlet valve of the tube furnace, cool to room temperature under sealed conditions, then take out the pyrolysis product, grind the pyrolysis product and pass it through a 200-mesh screen to obtain a magnetic mercury removal adsorbent.

[0011] Further, the waste plastics in step S1 are one or more of PET, PPS, PVC, PS or PE, and the carbon content of the waste plastics is 30~50wt.%.

[0012] Note: The preferred waste plastics are common waste plastic raw materials, which are low in cost and easy to obtain.

[0013] Furthermore, the waste battery tailings in step S1 are waste ternary lithium battery acid leaching residues, and their elemental composition and mass percentage are: S 16~20%, Si 5~8%, Al 10~12%, Ca 15~18%, Ni 2~3%, Ba 2~3%, Fe balance.

[0014] Note: The preferred raw material is the acid leaching residue from waste ternary lithium batteries, which is readily available and inexpensive.

[0015] Furthermore, the stirring method in step S1 is as follows: waste battery residue and waste plastic particles are placed in a rolling mixer, the stirring speed is set to 60~80 rpm, and the stirring time is 30 min.

[0016] Instructions: Stirring ensures that waste battery residue and waste plastic granules are evenly mixed.

[0017] Furthermore, the room temperature in steps S2 and S3 is 25~37℃.

[0018] Furthermore, in step S3, the internal temperature of the tubular furnace is 280~300℃ when the N2 purging is turned off.

[0019] Explanation: Controlling the internal temperature of the tubular furnace when N2 purging is turned off is to alleviate the thermal expansion and contraction effect caused by instantaneous cooling, and to prevent pyrolysis gas generated by residual plastic particles from remaining in the furnace and affecting the formation of pyrolysis products.

[0020] The magnetic mercury removal adsorbent prepared by the above-mentioned method of preparing magnetic mercury removal adsorbent from waste plastics and waste battery tailings is applied to the removal of gaseous mercury from flue gas, including the following steps:

[0021] 30 mg of magnetic mercury removal adsorbent and 40 mg of quartz sand were mixed evenly to obtain the first adsorption powder. 20 mg of magnetic mercury removal adsorbent and 30 mg of quartz sand were mixed evenly to obtain the second adsorption powder. The first adsorption powder was sprinkled onto quartz wool to form the first adsorption section. The first adsorption section was placed in the middle of a circular tube with an inner diameter of 6-8 mm and compressed to a length of 1-1.5 cm. A 1-1.2 cm long piece of quartz wool was placed at the front end of the first adsorption section as a sealing section. A 1-1.5 cm long piece of quartz wool was placed at the rear end of the first adsorption section as a supplementary section. A supplementary tube was installed on the circular tube at this location. The second adsorption section was placed at the rear end of the supplementary section, and a 1-1.2 cm long sealing section was placed at the rear end of the second adsorption section. Then, the second adsorption section was placed into the circular tube. Mercury-containing flue gas is introduced into the tube and passes through the first adsorption section, the replenishment section, and the second adsorption section sequentially from front to back. The flow rate of the mercury-containing flue gas is 1~1.2L / min. The middle part of the circular tube is heated by an external heater at a temperature of 120℃ for 0.5h. Then the gas supply is stopped, the sealing plug of the replenishment tube is opened, and the second adsorption powder is added to it so that it adheres to the quartz wool inside the replenishment section. The sealing plug of the replenishment tube is closed, and mercury-containing flue gas is introduced again under the same conditions for another 0.5h. The mercury concentration of the treated mercury-containing flue gas is measured using a mercury analyzer to complete one reaction cycle. The quartz wool inside the replenishment section with the second adsorption powder attached in this reaction cycle is then used as the second adsorption section in the next reaction cycle.

[0022] Furthermore, the mercury-containing flue gas contains HgO with a mass concentration of 100 μg / m³. 3 Nitrogen gas.

[0023] Furthermore, in the first reaction cycle, the second adsorption section is the same as the first adsorption section.

[0024] Note: By applying the supplementary stage to the second adsorption stage of the next reaction cycle, the utilization rate of the adsorption powder can be improved, raw materials can be saved, and the problem of decreased adsorption efficiency due to prolonged reaction of the adsorption powder can be avoided.

[0025] The beneficial effects of this invention are:

[0026] The present invention discloses a method for preparing magnetic mercury removal adsorbents from waste plastics and waste battery tailings. Using waste battery acid extraction tailings and waste plastics as precursors, the method employs a simple pyrolysis reaction to synthesize the magnetic mercury removal adsorbent. The raw materials are readily available and inexpensive, the preparation method is simple, and it is easy to achieve industrial-scale application. The prepared magnetic mercury removal adsorbent has many advantages such as high mercury removal efficiency, strong acid and water resistance, magnetic recovery capability, and high-temperature regeneration capability. This provides a new preparation method for magnetic recyclable flue gas mercury removal adsorbents.

[0027] The present invention provides a method for preparing magnetic mercury removal adsorbents by co-processing waste plastics with waste battery tailings. This method uses waste battery acid extraction tailings and waste plastics as pyrolysis substrates, which solves the problem of recycling bulk solid waste battery leaching tailings and waste plastics, and expands the ways to jointly utilize battery acid extraction waste and waste plastics for resource recovery and high-value utilization.

[0028] The method for preparing magnetic mercury removal adsorbent from waste plastics and waste battery tailings of the present invention controls the internal temperature of the tubular furnace when N2 purging is turned off. This is to alleviate the thermal expansion and contraction effect caused by instantaneous cooling, and to prevent the pyrolysis gas generated by residual plastic particles from remaining in the furnace and affecting the generation of pyrolysis products.

[0029] In the application of the present invention of preparing magnetic mercury removal adsorbent from waste plastics and waste battery tailings, by applying the supplementary stage to the second adsorption stage of the next reaction cycle, the utilization rate of the adsorption powder can be improved, raw materials can be saved, and the problem of decreased adsorption efficiency of adsorption powder during long-term reaction can be avoided. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the application structure of the present invention for preparing magnetic mercury removal adsorbent from waste plastics and waste battery tailings;

[0031] Figure 2 These are the mercury removal characteristic curves of the magnetic mercury removal adsorbents prepared under different main preparation parameters in Examples 1-15 of this invention;

[0032] Figure 3 This refers to the magnetization characteristics of the magnetic mercury removal adsorbent prepared in Example 13 of this invention.

[0033] Among them, 1-first adsorption section, 2-second adsorption section, 3-replenishment section, 4-external heater, 5-end sealing section, 6-replenishment tube. Detailed Implementation Example 1

[0034] A method for preparing a magnetic mercury removal adsorbent from waste plastics and waste battery residue includes the following steps:

[0035] S1. Premixing treatment: Waste plastic is crushed, ground, and passed through a 200-mesh sieve to obtain waste plastic granules. Waste battery tail residue is passed through a 200-mesh sieve and mixed with waste plastic granules at a mass ratio of 1:0.17. The mixing method is as follows: Waste battery tail residue and waste plastic granules are placed in a rolling mixer, the mixing speed is set to 70 rpm, and the mixing time is 30 min to obtain mixed powder.

[0036] The waste plastic is PPS, and the carbon content of the waste plastic is 40 wt.%.

[0037] The waste battery tailings are acid leaching residues from waste ternary lithium batteries. Their elemental composition and mass percentages are as follows: S 18.876%, Si 6.283%, Al 11.24%, Ca 17.718%, Ni 2.157%, Ba 2.978%, Fe 27.601%, and other impurities: Mg 0.482%, K 0.219%, Sc 0.222%, Ti 0.228%, Cr 1.624%, Mn 0.325%, Co 0.468%, Cu 0.998%, Zn 0.096%, As 0.118%, Sr 0.043%, Y 0.018%, Zr 0.039%, Mo 0.019%, W 0.520%, Pb 0.076%.

[0038] S2. Pyrolysis reaction: 10g of mixed powder was loaded into a quartz boat and placed in a tube furnace. The furnace was purged with N2 at room temperature beforehand. The N2 flow rate was set to 1.2L / min. After purging at room temperature for 5min, the tube furnace was raised to the target temperature of 500℃ at a heating rate of 8℃ / min. The temperature was kept constant and the pyrolysis reaction was continued for 6h.

[0039] S3. Post-processing: After the pyrolysis reaction is completed, stop heating and maintain N2 purging for 1 hour. Then turn off N2 purging. When N2 purging is turned off, the internal temperature of the tubular furnace is 290℃. At the same time, close the inlet / outlet valves of the tubular furnace. After cooling to room temperature under sealed conditions, take out the pyrolysis product, grind the pyrolysis product and pass it through a 200-mesh sieve to obtain the magnetic mercury removal adsorbent. The room temperature is 28℃. Example 2

[0040] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0041] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.33. Example 3

[0042] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0043] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.5. Example 4

[0044] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0045] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.75. Example 5

[0046] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0047] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:1. Example 6

[0048] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0049] The target temperature for the pyrolysis reaction in step S2 is 600℃. Example 7

[0050] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0051] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.33. The target temperature for the pyrolysis reaction in step S2 is 600℃. Example 8

[0052] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0053] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.5. The target temperature for the pyrolysis reaction in step S2 is 600℃. Example 9

[0054] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0055] Waste battery residue is mixed with waste plastic particles at a mass ratio of 1:0.75. The target temperature for the pyrolysis reaction in step S2 is 600℃. Example 10

[0056] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0057] Waste battery residue is mixed with waste plastic particles at a mass ratio of 1:1 and stirred. The target temperature for the pyrolysis reaction in step S2 is 600℃. Example 11

[0058] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0059] The target temperature for the pyrolysis reaction in step S2 is 700℃. Example 12

[0060] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0061] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.33, and the target temperature for the pyrolysis reaction in step S2 is 700℃. Example 13

[0062] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0063] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.5. The target temperature for the pyrolysis reaction in step S2 is 700℃. Example 14

[0064] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0065] Waste battery residue is mixed with waste plastic granules at a mass ratio of 1:0.75. The target temperature for the pyrolysis reaction in step S2 is 700℃. Example 15

[0066] The difference between this embodiment and Embodiment 1 is that the main parameters are different.

[0067] Waste battery residue is mixed with waste plastic particles at a mass ratio of 1:1 and stirred. The target temperature for the pyrolysis reaction in step S2 is 700℃. Example 16

[0068] The difference between this embodiment and Embodiment 1 is that the secondary parameters are different.

[0069] S1. Premixing treatment: Waste plastic is crushed, ground, and passed through a 200-mesh sieve to obtain waste plastic granules. Waste battery tail residue is passed through a 200-mesh sieve and mixed with waste plastic granules at a mass ratio of 1:0.17. The mixing method is as follows: Waste battery tail residue and waste plastic granules are placed in a rolling mixer, the mixing speed is set to 60 rpm, and the mixing time is 30 min to obtain mixed powder.

[0070] The waste plastic is PET, and its carbon content is 30 wt.%.

[0071] The waste battery tailings are the acid leaching residue of waste ternary lithium batteries. Its elemental composition and mass percentage are: S 16%, Si 5%, Al 10%, Ca 15%, Ni 2%, Ba 2%, Fe balance.

[0072] S2. Pyrolysis reaction: 10g of mixed powder was loaded into a quartz boat and placed in a tube furnace. The furnace was purged with N2 at room temperature beforehand. The N2 flow rate was set to 1L / min. After purging at room temperature for 5min, the tube furnace was raised to the target temperature of 500℃ at a heating rate of 7℃ / min. The temperature was kept constant and the pyrolysis reaction was continued for 6h.

[0073] S3. Post-processing: After the pyrolysis reaction is completed, stop heating and maintain N2 purging for 0.5 h. Then turn off N2 purging. When N2 purging is turned off, the internal temperature of the tubular furnace is 280℃. At the same time, close the inlet / outlet valves of the tubular furnace. After cooling to room temperature under sealed conditions, take out the pyrolysis product, grind the pyrolysis product and pass it through a 200-mesh sieve to obtain the magnetic mercury removal adsorbent. The room temperature is 25℃. Example 17

[0074] The difference between this embodiment and Embodiment 1 is that the secondary parameters are different.

[0075] S1. Premixing treatment: Waste plastic is crushed, ground, and passed through a 200-mesh sieve to obtain waste plastic granules. Waste battery tail residue is passed through a 200-mesh sieve and mixed with waste plastic granules at a mass ratio of 1:0.17. The mixing method is as follows: Waste battery tail residue and waste plastic granules are placed in a rolling mixer, the mixing speed is set to 80 rpm, and the mixing time is 30 min to obtain mixed powder.

[0076] The waste plastics are a mixture of PVC, PS, and PE in equal proportions, and the carbon content of the waste plastics is 50 wt.%.

[0077] The waste battery tailings are the acid leaching residue of waste ternary lithium batteries. Its elemental composition and mass percentage are: S 16%, Si 5%, Al 10%, Ca 15%, Ni 2%, Ba 2%, Fe balance.

[0078] S2. Pyrolysis reaction: 10g of mixed powder was loaded into a quartz boat and placed in a tube furnace. The furnace was purged with N2 at room temperature beforehand. The N2 flow rate was set to 1.5L / min. After purging at room temperature for 5min, the tube furnace was raised to the target temperature of 500℃ at a heating rate of 10℃ / min. The temperature was kept constant and the pyrolysis reaction was continued for 6h.

[0079] S3. Post-processing: After the pyrolysis reaction is completed, stop heating and maintain N2 purging for 1.5 hours. Then turn off N2 purging. When N2 purging is turned off, the internal temperature of the tubular furnace is 300℃. At the same time, close the inlet / outlet valves of the tubular furnace. After cooling to room temperature under sealed conditions, take out the pyrolysis product, grind the pyrolysis product and pass it through a 200-mesh sieve to obtain the magnetic mercury removal adsorbent. The room temperature is 37℃. Example 18

[0080] This embodiment describes the application of the magnetic mercury removal adsorbent prepared by the method of preparing magnetic mercury removal adsorbent from waste plastics and waste battery tailings in Example 1. The adsorbent is applied to the removal of gaseous mercury from flue gas, and includes the following steps:

[0081] 30 mg of magnetic mercury removal adsorbent was mixed with 40 mg of quartz sand to obtain the first adsorption powder. 20 mg of magnetic mercury removal adsorbent was mixed with 30 mg of quartz sand to obtain the second adsorption powder. The first adsorption powder was sprinkled onto quartz wool to form the first adsorption section 1. The first adsorption section 1 was placed in the middle of a 7 mm inner diameter circular tube and compressed to a length of 1.2 cm. A 1.1 cm long quartz wool was placed at the front end of the first adsorption section 1 as a sealing section 5. A 1.2 cm long quartz wool was placed at the rear end of the first adsorption section 1 as a supplementary section 3. A supplementary tube 6 was installed on the circular tube at this location. The second adsorption section 2 was placed at the rear end of the supplementary section 3, and a 1.1 cm long sealing section 5 was placed at the rear end of the second adsorption section 2. Mercury-containing flue gas was then introduced into the circular tube, passing sequentially through the first adsorption section 1, the supplementary section 3, and the second adsorption section 2. The flow rate of the mercury-containing flue gas was 1.1 L / min, and the mercury-containing flue gas contained 100 μg / m³ of HgO. 3 Nitrogen gas is used to heat the middle of the circular tube at 120°C via an external heater 4 for 0.5 hours. Afterward, the gas flow is stopped, the sealing plug of the replenishment tube 6 is opened, and the second adsorption powder is added to adhere to the quartz wool inside the replenishment section 3. The sealing plug of the replenishment tube 6 is then closed, and mercury-containing flue gas is continued to flow under the same conditions for another 0.5 hours. The mercury concentration of the treated mercury-containing flue gas is measured using a mercury analyzer, completing one reaction cycle. The quartz wool inside the replenishment section 3 with the second adsorption powder attached from this reaction cycle is then used as the second adsorption section 2 for the next reaction cycle. In the first reaction cycle, the second adsorption section 2 has the same length and filling material as the first adsorption section 1. Example 19

[0082] The difference between this embodiment and embodiment 18 is that:

[0083] The first adsorption section 1 is placed in the middle of a circular tube with an inner diameter of 6 mm and compressed to a length of 1 cm. A 1 cm long piece of quartz wool is placed at the front end of the first adsorption section 1 as a sealing section 5, and a 1 cm long piece of quartz wool is placed at the rear end of the first adsorption section 1 as a supplementary section 3. A supplementary tube 6 is provided on the circular tube at this position. The second adsorption section 2 is placed at the rear end of the supplementary section 3, and a 1 cm long sealing section 5 is placed at the rear end of the second adsorption section 2. Then, mercury-containing flue gas is introduced into the circular tube and passes through the first adsorption section 1, the supplementary section 3, and the second adsorption section 2 in sequence from front to back. The flow rate of the mercury-containing flue gas is 1 L / min. Example 20

[0084] The difference between this embodiment and embodiment 18 is that:

[0085] The first adsorption section 1 is placed in the middle of a circular tube with an inner diameter of 8 mm and compressed to a length of 1.5 cm. A quartz wool with a length of 1.2 cm is placed at the front end of the first adsorption section 1 as a sealing section 5. A quartz wool with a length of 1.5 cm is placed at the rear end of the first adsorption section 1 as a supplementary section 3. A supplementary tube 6 is provided on the circular tube at this position. The second adsorption section 2 is placed at the rear end of the supplementary section 3. A 1.2 cm sealing section 5 is placed at the rear end of the second adsorption section 2. Then, mercury-containing flue gas is introduced into the circular tube and passes through the first adsorption section 1, the supplementary section 3 and the second adsorption section 2 in sequence from front to back. The flow rate of the mercury-containing flue gas is 1.2 L / min.

[0086] Experimental Example

[0087] The magnetic mercury removal adsorbents prepared in Examples 1-15 were tested, and the operation method in Example 18 was followed in all cases. The mercury removal data of the mercury-containing flue gas were statistically analyzed. Figure 2 As shown, the preparation parameters in Examples 5, 6 and 15 can achieve the best adsorption treatment effect.

[0088] like Figure 3 It can be seen that at room temperature, the adsorbent in Example 13 exhibits a significant increase in magnetic moment as the magnetic field strength increases in a magnetic field of ±2T. When the magnetic field strength reaches 2T, the magnetic moment is not yet saturated, demonstrating the adsorbent's good magnetism and excellent magnetic recovery potential.

Claims

1. A method for preparing a magnetic demercuration adsorbent from waste plastics in synergy with spent battery tailings, characterized by, Comprising the following steps: S1, premixing treatment: crushing and grinding the waste plastics, then passing through a 200-mesh screen to obtain waste plastic particles, and passing the waste battery tailings through a 200-mesh screen, then mixing and stirring with the waste plastic particles at a mass ratio of 1:0.17~1 to obtain a mixed powder; The waste plastics are one or more of PET, PPS, PVC, PS or PE, and the carbon content of the waste plastics is 30~50wt.%; The waste battery tailings are waste acid leaching residues of waste ternary lithium batteries, and the elemental composition and mass percentage are: S 16~20%, Si 5~8%, Al 10~12%, Ca 15~18%, Ni 2~3%, Ba 2~3%, and Fe balance; S2, pyrolysis reaction: 10g of the mixed powder is taken with a quartz boat and placed in a tube furnace, the furnace is pre-purged at room temperature with N2, the N2 flow rate is set to 1~1.5L / min, after purging for 5min, the tube furnace is heated to a target temperature of 500~700℃ at a heating rate of 7~10℃ / min, and the temperature is kept constant for 6h of pyrolysis reaction; S3, post-treatment: after the pyrolysis reaction is completed, heating is stopped, N2 purging is maintained for 0.5~1.5h, then the N2 purging is turned off, the inlet / outlet valve of the tube furnace is closed, and after cooling to room temperature under airtight conditions, the pyrolysis product is taken out, ground and passed through a 200-mesh screen to obtain a magnetic mercury removal adsorbent.

2. The process for the preparation of magnetic demercury adsorbent from waste plastics in synergy with spent battery residues as claimed in claim 1 wherein, The stirring method in step S1 is: placing the waste battery tailings and waste plastic particles in a rolling stirrer, setting the stirring speed to 60~80rpm, and stirring for 30min.

3. The method of producing magnetic demercury adsorbent from waste plastics in synergy with spent battery tailings as claimed in claim 1, wherein, The room temperature in steps S2 and S3 is 25~37℃.

4. The method of producing magnetic demercury adsorbent from waste plastics in synergy with spent battery tailings as claimed in claim 1, wherein, The internal temperature of the tube furnace when the N2 purging is turned off in step S3 is 280~300℃.

5. The method for preparing the magnetic mercury-removal adsorbent from waste plastics and spent battery tailings according to any one of claims 1-4, the use of the magnetic mercury-removal adsorbent prepared by the method, characterized in that, Its application in the removal of gaseous mercury in flue gas comprises the following steps: Mix 30 mg of magnetic mercury removal adsorbent with 40 mg of quartz sand to obtain a first adsorption powder, mix 20 mg of magnetic mercury removal adsorbent with 30 mg of quartz sand to obtain a second adsorption powder, spread the first adsorption powder on the quartz wool to obtain a first adsorption section (1), place the first adsorption section (1) in the middle of a round tube with an inner diameter of 6-8 mm and compress it to a length of 1-1.5 cm, place quartz wool with a length of 1-1.2 cm at the front end of the first adsorption section (1) as an end cap section (5), place quartz wool with a length of 1-1.5 cm at the rear end of the first adsorption section (1) as a supplement section (3), and provide a supplement tube (6) on the round tube at this position, place a second adsorption section (2) at the rear end of the supplement section (3), and place an end cap section (5) with a length of 1-1.2 cm at the rear end of the second adsorption section (2), then introduce mercury-containing flue gas into the interior of the round tube, and the mercury-containing flue gas passes through the first adsorption section (1), the supplement section (3), and the second adsorption section (2) in turn, the flow rate of the mercury-containing flue gas is 1-1.2 L / min, heat the middle part of the round tube by an external heater (4), the heating temperature is 120°C, and the reaction time is 0.5 h, then stop the gas supply, open the sealing plug of the supplement tube (6), add the second adsorption powder to the interior of the supplement section (3) to adhere to the quartz wool, close the sealing plug of the supplement tube (6), continue to supply mercury-containing flue gas, and the reaction time is 0.5 h under the same conditions as above, determine the mercury concentration of the treated mercury-containing flue gas using a mercury analyzer, complete one reaction cycle, and then use the quartz wool in the supplement section (3) of the reaction cycle with the second adsorption powder adhered as the second adsorption section (2) in the next reaction cycle.

6. Use of waste plastics in synergic waste battery tailings for the preparation of magnetic demercuration adsorbents according to claim 5, characterized in that, The mercury-containing flue gas has a Hg0 mass concentration of 100 ug / m 3 of nitrogen.

7. Use of waste plastic in synergic waste battery tailings for the preparation of magnetic demercuration adsorbents according to claim 5, characterized in that, In the first reaction cycle, the second adsorption section (2) is the same as the first adsorption section (1).

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