Heavy metal adsorbent based on waste SCR denitration catalyst and preparation method thereof

Abstract

The invention relates to the technical field of waste catalyst resource utilization, in particular to a waste SCR denitration catalyst based heavy metal adsorbent and a preparation method thereof.The preparation method comprises the following steps that a waste SCR denitration catalyst is placed in a mixed solution of sulfuric acid and organic acid to be subjected to acid leaching treatment, and after filtering and drying treatment, the waste SCR denitration catalyst is obtained; catalyst powder subjected to acid leaching treatment is obtained; mixing the catalyst powder subjected to acid leaching treatment with a mineral material, adding a metal oxide, and carrying out ball milling treatment in a high-energy ball mill; and adding an organic binder into the ball-milled powder, and uniformly mixing to obtain the heavy metal adsorbent. Through the steps of chemical extraction, physical mixing, activity excitation and the like, the waste SCR denitration catalyst is converted into the composite material with the efficient heavy metal ion adsorption capacity, efficient resource utilization of the waste SCR denitration catalyst is achieved, and meanwhile a new solution is provided for water body heavy metal pollution treatment in China.

Description

Technical Field

[0001] The present invention relates to the technical field of waste catalyst resource utilization, and in particular to a heavy metal adsorbent based on a waste SCR denitration catalyst and a preparation method thereof. Background Art

[0002] SCR (Selective Catalytic Reduction) denitrification catalyst plays a vital role in the denitrification project of coal-fired boilers, effectively reducing nitrogen oxide emissions in flue gas through catalytic reduction reactions. However, in the actual operation of the project, these catalysts will gradually deactivate due to long-term exposure to complex environments such as high-temperature flue gas, fly ash and chemical corrosion. According to statistics, about 60% of the deactivated denitrification catalysts can restore their activity through professional regeneration technology and continue to be put into use. However, the remaining 40% of the catalysts cannot be restored by regeneration due to irreversible damage such as structural damage and thermal sintering, thus becoming a solid waste problem that needs to be solved urgently.

[0003] Currently, no efficient and economical resource utilization process has been developed for this part of the waste SCR denitrification catalyst that cannot be regenerated. This not only causes a waste of resources, but may also cause environmental pollution due to improper disposal, becoming a major challenge in the field of environmental protection.

[0004] At the same time, heavy metal pollution has become one of the important sources of pollution in my country's surface water and groundwater. Heavy metal elements such as Pb (lead), Cd (cadmium), and Cr (chromium) are difficult to degrade and easy to accumulate. They will not only cause long-term harm to the aquatic ecosystem, but also be transmitted through the food chain, seriously threatening human health. Therefore, it is particularly important to develop efficient and economical heavy metal removal technology for water bodies.

[0005] Among the many technologies for removing heavy metals from water bodies, adsorption is considered to be one of the technologies with the greatest application potential due to its advantages such as low cost, high removal efficiency and no secondary pollution. The core of the adsorption method lies in the selection of adsorbents, whose performance directly determines the removal effect of heavy metal ions.

[0006] In recent years, domestic and foreign scholars have made many advances in the field of adsorbent preparation, and a variety of new adsorbents have been introduced. For example, Chinese invention patent CN118479626A discloses a groundwater heavy metal pollution remediation agent, which is composed of limestone, zeolite, pumice, hydroxyapatite and steel slag and other materials, aiming to improve adsorption efficiency and stability. For another example, Chinese invention patent CN113117634A discloses a heavy metal adsorbent, which has polytitanium phosphate as the main component and exhibits good heavy metal removal performance.

[0007] Although these new adsorbents have promoted the development of heavy metal removal technology in water bodies to a certain extent, they still have limitations such as limited adsorption capacity and being greatly affected by pH value. Especially for complex and changeable industrial wastewater, a single adsorbent is often difficult to meet the needs of efficient and stable removal.

[0008] In view of this, the present invention aims to provide a heavy metal adsorption material based on waste SCR denitrification catalyst and a preparation method thereof, aiming to overcome the deficiencies of existing adsorbents in terms of adsorption capacity, pH adaptability, etc., to achieve efficient resource utilization of waste SCR denitrification catalysts, and at the same time provide a new solution for the control of heavy metal pollution in my country's water bodies. Summary of the invention

[0009] The purpose of the present invention is to provide a heavy metal adsorbent based on waste SCR denitration catalyst and a preparation method thereof, which can convert the waste SCR denitration catalyst into a composite material with high-efficiency heavy metal ion adsorption capacity, which not only realizes the efficient resource utilization of the waste SCR denitration catalyst, but also provides a new solution for the control of heavy metal pollution in my country's water bodies.

[0010] The present invention provides a method for preparing a heavy metal adsorbent based on a waste SCR denitration catalyst, comprising the following steps:

[0011] S1. The waste SCR denitration catalyst is placed in a mixed solution of sulfuric acid and organic acid for acid leaching, and after filtering and drying, the catalyst powder after acid leaching is obtained;

[0012] S2, mixing the catalyst powder after acid leaching with mineral materials, adding metal oxides, and placing in a high-energy ball mill for ball milling;

[0013] S3. Add an organic binder to the ball-milled powder and mix well to obtain a heavy metal adsorbent.

[0014] In the preparation method of the heavy metal adsorbent of the present invention, first, the waste SCR denitration catalyst is acid-leached using sulfuric acid and an organic acid, wherein sulfuric acid, as a strong acid, can destroy the chemical bonds on the surface of the waste SCR denitration catalyst and release the valuable elements therein, such as V, W, Mo, etc., while organic acids (such as oxalic acid, formic acid and oxalic acid) have a complexing effect and can form a complex with the valuable elements, thereby facilitating the dissolution and extraction of the valuable elements. At the same time, the organic acid can also adjust the pH value of the solution, making the acid leaching process more gentle and reducing damage to the catalyst structure. Therefore, the present invention uses sulfuric acid and organic acid for compounding to fully utilize the advantages of both and achieve synergistic effects. The compounded acid leaching solution has higher reactivity and selectivity, and can more effectively extract the valuable elements in the waste SCR denitration catalyst. Then, the catalyst powder after acid leaching is mixed with mineral materials (attapulgite, sepiolite, montmorillonite, vermiculite, kaolin, etc.), and the good adsorption, ion exchange and chemical stability of the mineral materials are used to form a good composite structure with the waste SCR denitration catalyst. Further, in the powder of the waste SCR denitration catalyst mixed with the mineral materials, metal oxides such as CaO, MgO, and ZnO are added. These metal oxides can serve as ion exchange sites to further enhance the removal performance of the composite material for heavy metal ions. At the same time, in the ball milling of a high-energy ball mill (such as a plasma ball mill), the waste SCR denitration catalyst powder, mineral materials and metal oxides can be homogenously mixed, and the impact force and shear force generated during the ball milling process can destroy the oxide layer on the surface of the particles, promote the physical and chemical reaction between the particles, thereby achieving deeper mixing and reaction. Finally, an organic binder is added to the powder after ball milling to increase the stability and mechanical strength of the composite material to ensure that it will not break or peel off during subsequent use and handling.

[0015] As a preferred embodiment of the present technical solution, in step S1, during the acid leaching process of the present invention, the mass concentration of sulfuric acid used is 5%-10%, the mass concentration of organic acid is 0.5%-2%, and the organic acid includes any one or more of oxalic acid, formic acid and oxalic acid.

[0016] Studies have shown that during the acid leaching process, appropriate leaching concentration and temperature can accelerate chemical reactions and increase the leaching rate of valuable elements. Specifically, during the acid leaching treatment of the present invention, the solid-liquid ratio can be controlled to be 1: (10-20), the acid leaching temperature is 60-80°C, and the stirring time is 0.5-2h.

[0017] As a preferred embodiment of the present technical solution, during the stirring, high-speed shear stirring is adopted, and the stirring speed is controlled to be 10000-18000 rpm, so as to more effectively dissolve and extract the valuable elements.

[0018] As a preferred embodiment of the present technical solution, in step S2, the mineral material includes any one or more of attapulgite, sepiolite, montmorillonite, vermiculite and kaolin, and the mass ratio of the catalyst powder after acid leaching to the mineral material is 1:(1-4). The addition of the mineral material of the present invention not only helps to increase the specific surface area and porosity of the composite material, but also improves the overall stability and mechanical strength of the material.

[0019] As a preferred embodiment of the present technical solution, in step S2, the metal oxide used in the present invention includes one of CaO, MgO and ZnO, and the added amount of the metal oxide is 5%-15% of the total mass of the catalyst powder and the mineral material after acid leaching treatment.

[0020] As a preferred embodiment of the present technical solution, in step S2, the high-energy ball mill is a plasma ball mill, and during ball milling, it is preferred to control the plasma ball mill to have an Ar atmosphere, a pressure of 0.1-0.3 MPa, a plasma power supply discharge voltage of 20-25 kV, and a discharge frequency of 10-15 kHz, so as to further stimulate the adsorption active sites on the surface of TiO2 and mineral materials and improve the adsorption capacity of the composite material for heavy metal ions.

[0021] As a preferred embodiment of the present technical solution, in step S3, the organic binder is any one or more of sesbania powder, polyethylene oxide and cellulose. The addition of the above organic binder can not only significantly improve the compressive strength, wear resistance and corrosion resistance of the composite material, but also improve the formability of the composite material, making it easier to be made into an adsorption material of the desired shape and size through processes such as ball rolling. In addition, the type and content of the organic binder also have a certain influence on the porosity and specific surface area of ​​the composite material. When the amount of the organic binder added is 2%-4% of the total mass of the catalyst powder and the mineral material after acid leaching treatment, the pore structure and specific surface area of ​​the composite material can be optimized to a certain extent, thereby improving its adsorption capacity for heavy metal ions.

[0022] In the second aspect, the present invention also discloses a heavy metal adsorbent based on a waste SCR denitration catalyst prepared according to the above method, which should also fall within the protection scope of the present invention.

[0023] The method for preparing a heavy metal adsorbent based on a discarded SCR denitration catalyst of the present invention has at least the following beneficial effects:

[0024] In the preparation method of the heavy metal adsorbent based on the waste SCR denitration catalyst of the present invention, first, the SCR denitration catalyst is placed in a mixed solution of sulfuric acid and organic acid for acid leaching treatment, and the chemical bonds on the surface of the waste SCR denitration catalyst are destroyed by the strong acidity of sulfuric acid and the complexing effect of the organic acid, so as to more effectively dissolve and extract the valuable elements such as V, W, Mo in the catalyst; then, the catalyst powder after the acid leaching treatment is mixed with a mineral material, and a metal oxide is added, and the catalyst is placed in a high-energy ball mill for ball milling treatment. On the one hand, the adsorption active sites on the surface of TiO2 and the mineral material are stimulated by the plasma ball milling effect, thereby improving the contact area and binding capacity of the composite material for heavy metal ions. On the other hand, the addition of the metal oxide provides the composite material with ion exchange sites for heavy metal ions, and these sites can exchange reactions with a variety of heavy metal ions, thereby further improving the performance of the adsorption material in adsorbing heavy metal ions; finally, the powder after the ball milling treatment is mixed with an organic binder to obtain a heavy metal adsorbent. Studies have shown that the heavy metal adsorbent prepared by the present invention can simultaneously adsorb heavy metal ions such as Pb(II), Cd(II), Cu(II) and Ni(II) in wastewater, and has a relatively high adsorption capacity at a pH of 4-8, effectively overcoming the shortcomings of existing adsorbents in terms of adsorption capacity, pH adaptability, etc.

[0025] Therefore, the present invention converts the waste SCR denitrification catalyst into a composite material with high-efficiency heavy metal ion adsorption capacity through the steps of chemical extraction, physical mixing and activity excitation, which not only realizes the efficient resource utilization of the waste SCR denitrification catalyst, but also provides a new solution for the control of heavy metal pollution in my country's water bodies. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] S1. Take the waste SCR denitration catalyst, remove the dust on the surface, crush and grind it, and immerse the powder in a mixed solution of sulfuric acid and oxalic acid at a solid-liquid ratio of 1:10, wherein the concentration of the sulfuric acid solution is 10wt%, and the concentration of the oxalic acid solution is 0.5wt%, at a temperature of 60°C, high-speed shear stirring for 0.5h, and the stirring speed is 18000rpm; then, filter and dry to obtain catalyst powder after acid leaching;

[0031] S2, mixing the catalyst powder after acid leaching with attapulgite in a mass ratio of 1:1 between the catalyst powder after acid leaching and the mineral material, adding CaO and placing in a plasma ball mill for ball milling for 0.5h, wherein the amount of CaO added is 5% of the total mass of the catalyst powder after acid leaching and the mineral material;

[0032] S3, mixing the ball-milled powder with sesbania powder, wherein the amount of sesbania powder added is 2% of the powder mass, and rolling into a ball to obtain a heavy metal adsorbent with a diameter of 3 cm.

[0033] Example 2

[0034] S1. Take the waste SCR denitration catalyst, remove the dust on the surface, crush and grind it, and immerse the powder in a mixed solution of sulfuric acid and formic acid at a solid-liquid ratio of 1:20, wherein the concentration of the sulfuric acid solution is 5wt%, and the concentration of the formic acid solution is 2wt%. At a temperature of 80°C, high-speed shear stirring is performed for 2h at a stirring speed of 10000rpm; then, filter and dry to obtain catalyst powder after acid leaching;

[0035] S2, mixing the catalyst powder after acid leaching with sepiolite at a mass ratio of 1:4 between the catalyst powder after acid leaching and the mineral material, adding MgO and placing in a plasma ball mill for ball milling for 2 hours, wherein the amount of MgO added is 15% of the total mass of the catalyst powder after acid leaching and the mineral material;

[0036] S3, mixing the powder after ball milling with polyethylene oxide in an amount of 4% of the powder mass, rolling into balls to obtain a heavy metal adsorbent with a diameter of 10 cm.

[0037] Example 3

[0038] S1. Take the waste SCR denitration catalyst, remove the dust on the surface, crush and grind it, and immerse the powder in a mixed solution of sulfuric acid and oxalic acid at a solid-liquid ratio of 1:15, wherein the concentration of the sulfuric acid solution is 8wt%, and the concentration of the oxalic acid solution is 1wt%, at a temperature of 70°C, high-speed shear stirring for 1h, and the stirring speed is 15000rpm; then, filter and dry to obtain the catalyst powder after acid leaching;

[0039] S2, mixing the catalyst powder after acid leaching with montmorillonite at a mass ratio of 1:2 between the catalyst powder after acid leaching and the mineral material, adding ZnO and placing in a plasma ball mill for ball milling for 1 hour, wherein the amount of ZnO added is 10% of the total mass of the catalyst powder after acid leaching and the mineral material;

[0040] S3, mixing the powder after ball milling with cellulose, wherein the amount of cellulose added is 3% of the mass of the powder, and rolling into balls to obtain a heavy metal adsorbent with a diameter of 5 cm.

[0041] Example 4

[0042] S1. Take the waste SCR denitration catalyst, remove the dust on the surface, crush and grind it, and immerse the powder in a mixed solution of sulfuric acid and oxalic acid at a solid-liquid ratio of 1:10, wherein the concentration of the sulfuric acid solution is 6wt%, and the concentration of the oxalic acid solution is 2wt%, at a temperature of 80°C, high-speed shear stirring for 0.5h, and the stirring speed is 16000rpm; then, filter and dry to obtain catalyst powder after acid leaching;

[0043] S2, mixing the catalyst powder after acid leaching with vermiculite at a mass ratio of 1:3 between the catalyst powder after acid leaching and the mineral material, adding MgO and placing in a plasma ball mill for ball milling for 1 hour, wherein the amount of MgO added is 8% of the total mass of the catalyst powder after acid leaching and the mineral material;

[0044] S3, mixing the powder after ball milling with cellulose, wherein the amount of cellulose added is 2% of the mass of the powder, and rolling into balls to obtain a heavy metal adsorbent with a diameter of 6 cm.

[0045] Example 5

[0046] S1. Take the waste SCR denitration catalyst, remove the dust on the surface, crush and grind it, and immerse the powder in a mixed solution of sulfuric acid and formic acid at a solid-liquid ratio of 1:20, wherein the concentration of the sulfuric acid solution is 6wt%, and the concentration of the formic acid solution is 1.5wt%. At a temperature of 65°C, high-speed shear stirring is performed for 1.5h, and the stirring speed is 12000rpm; then, filtering and drying are performed to obtain catalyst powder after acid leaching;

[0047] S2, mixing the catalyst powder after acid leaching with sepiolite at a mass ratio of 1:2.5 between the catalyst powder after acid leaching and the mineral material, adding ZnO and placing in a plasma ball mill for ball milling for 1.5 hours, wherein the amount of ZnO added is 12% of the total mass of the catalyst powder after acid leaching and the mineral material;

[0048] S3, mixing the ball-milled powder with polyethylene oxide in an amount of 2.5% of the powder mass, and rolling the mixture into balls to obtain a heavy metal adsorbent with a diameter of 8 cm.

[0049] Comparative Example 1

[0050] This control example is basically the same as Example 1, except that: no mineral material and metal oxide are added to the catalyst powder after acid leaching for ball milling, and the catalyst powder after acid leaching is directly mixed with sesbania powder and rolled into balls.

[0051] Comparative Example 2

[0052] This control example is basically the same as Example 1, except that: waste SCR denitration catalyst is taken, the dust on the surface is removed, and then it is crushed and ground, and the powder is immersed in a mixed solution of sulfuric acid and hydrochloric acid at a solid-liquid ratio of 1:20, wherein the concentration of the sulfuric acid solution is 6wt%, and the concentration of the hydrochloric acid solution is 1.5wt%.

[0053] Test Example 1

[0054] The materials in Examples 1-5 and Comparative Examples 1-2 were placed in a conical flask, and a 200 mg / L Pb(II) solution was added at a feed ratio of 1 g / L. The conical flask was placed in a constant temperature shaker and shaken for a certain period of time at 25°C and 200 rpm. Subsequently, the conical flask was taken out, the concentration of Pb(II) in the solution was analyzed, and the removal rate of Pb(II) was calculated.

[0055] Table 1 Removal rate of Pb(II) by different adsorption materials

[0056]

[0057]

[0058] Test Example 2

[0059] The materials in Examples 1-5 and Comparative Examples 1-2 were placed in a conical flask, and a 50 mg / L Cd(II) solution was added at a feed ratio of 1 g / L. The conical flask was placed in a constant temperature shaker and shaken for a certain period of time at 25°C and 200 rpm. Subsequently, the conical flask was taken out, the concentration of Cd(II) in the solution was analyzed, and the removal rate of Cd(II) was calculated.

[0060] Table 2 Removal rate of Cd(II) by different adsorption materials

[0061] Oscillation 5h(%) Oscillation 10h(%) Example 1 74.9 99.8 Example 2 79.2 99.7 Example 3 84.3 99.7 Example 4 85.7 99.9 Example 5 84.5 99.9 Comparative Example 1 40.6 62.4 Comparative Example 2 45.1 67.5

[0062] Test Example 3

[0063] The materials in Examples 1-5 and Comparative Examples 1-2 were placed in a conical flask, and a 50 mg / L Cu(II) solution was added at a feed ratio of 1 g / L. The conical flask was placed in a constant temperature shaker and shaken for a certain period of time at 25°C and 200 rpm. Subsequently, the conical flask was taken out, the concentration of Cu(II) in the solution was analyzed, and the removal rate of Cu(II) was calculated.

[0064] Table 3 Removal rate of Cu(II) by different adsorption materials

[0065] Oscillation 10h(%) Oscillation 24h(%) Example 1 82.3 100 Example 2 87.2 100 Example 3 88.8 99.8 Example 4 87.9 98.4 Example 5 83.6 98.5 Comparative Example 1 27.5 55.1 Comparative Example 2 33.9 62.4

[0066] Test Example 4

[0067] The materials in Examples 1-5 and Comparative Examples 1-2 were placed in a conical flask, and a 50 mg / L Ni(II) solution was added at a feed ratio of 1 g / L. The conical flask was placed in a constant temperature shaker and shaken for a certain period of time at 25°C and 200 rpm. Subsequently, the conical flask was taken out, the concentration of Ni(II) in the solution was analyzed, and the removal rate of Ni(II) was calculated.

[0068] Table 4 Removal rate of Ni(II) by different adsorption materials

[0069] Oscillation 10h(%) Oscillation 24h(%) Example 1 83.4 100 Example 2 86.7 100 Example 3 89.6 99.9 Example 4 88.1 98.6 Example 5 84.8 98.8 Comparative Example 1 34.7 58.1 Comparative Example 2 41.6 65.7

[0070] Test Example 5

[0071] The material in Example 1 was placed in a conical flask, and a 200 mg / L Pb(II) solution was added at a feed ratio of 1 g / L. The pH value of the solution was adjusted using 0.1 M nitric acid or 0.1 M NaOH. The conical flask was placed in a constant temperature shaker and shaken for a certain period of time at 25°C and 200 rpm. Subsequently, the conical flask was taken out, the concentration of Pb(II) in the solution was analyzed, and the removal rate of Pb(II) by the adsorption material at different pH values ​​was calculated.

[0072] Table 5 Removal rate of Pb(II) by adsorption materials at different pH values

[0073] pH Removal rate (%) 1 38.5 2 58.3 3 81.5 4 95.2 5 100 6 100 7 100 8 100

[0074] It can be seen from Tables 1-5 that the heavy metal adsorbents prepared in Examples 1-5 of the present invention can simultaneously adsorb Pb(II), Cd(II), Cu(II) and Ni(II) heavy metal ions in wastewater, and have a high removal rate for heavy metal ions in the pH range of 3-8, effectively overcoming the shortcomings of existing adsorbents in terms of adsorption capacity, pH adaptability, etc.

[0075] Among them, in Control Example 1, mineral materials and metal oxides were not added to the catalyst powder after acid leaching for ball milling. The catalyst powder after acid leaching was directly mixed with field sesbania powder and rolled into balls. Although the prepared adsorption material has certain adsorption properties, the adsorption capacity for Pb(II), Cd(II), Cu(II) and Ni(II) heavy metal ions in wastewater is relatively low. This may be because the active sites on the surface of the SCR deNOx catalyst are not fully excited.

[0076] In Control Example 2, an inorganic mixed acid was used to acid-leach the SCR denitrification catalyst, and the adsorption performance of the prepared adsorption material was poorer than that of Example 1. This may be because although the use of an inorganic mixed acid can destroy chemical bonds to a large extent, it cannot effectively extract all valuable elements, especially those elements that are closely integrated with the catalyst structure. The inability to effectively extract valuable elements such as TiO2 will introduce secondary pollution and affect the adsorption performance of the adsorption material.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a heavy metal adsorbent based on a waste SCR denitration catalyst, characterized in that: The following steps are involved: S1. The waste SCR denitration catalyst is placed in a mixed solution of sulfuric acid and organic acid for acid leaching, and after filtering and drying, the catalyst powder after acid leaching is obtained; S2, mixing the catalyst powder after acid leaching with mineral materials, adding metal oxides, and placing in a high-energy ball mill for ball milling; S3. Add an organic binder to the ball-milled powder and mix well to obtain a heavy metal adsorbent.

2. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S1, the mass concentration of sulfuric acid is 5%-10%; The mass concentration of the organic acid is 0.5%-2%, and the organic acid includes any one or more of oxalic acid, formic acid and oxalic acid.

3. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S1, during the acid leaching treatment, the solid-liquid ratio is controlled to be 1:(10-20), the acid leaching temperature is 60-80° C., and the stirring time is 0.5-2 h.

4. The method for preparing a heavy metal adsorbent according to claim 3, characterized in that: During the stirring, high-speed shear stirring is adopted, and the stirring speed is controlled to be 10000-18000 rpm.

5. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S2, the mineral material includes any one or more of attapulgite, sepiolite, montmorillonite, vermiculite and kaolin, and the mass ratio of the catalyst powder after acid leaching to the mineral material is 1:(1-4).

6. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S2, the metal oxide includes one of CaO, MgO and ZnO, and the amount of the metal oxide added is 5%-15% of the total mass of the catalyst powder and the mineral material after the acid leaching treatment.

7. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S2, the high energy ball mill is a plasma ball mill.

8. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S2, during the ball milling, the ball milling tank is controlled to have an Ar atmosphere, a pressure of 0.1-0.3 MPa, a plasma power supply discharge voltage of 20-25 kV, and a discharge frequency of 10-15 kHz.

9. The method for preparing a heavy metal adsorbent according to claim 1, characterized in that: In step S3, the organic binder is any one or more of sesbania powder, polyethylene oxide and cellulose, and the amount of the organic binder added is 2%-4% of the total mass of the catalyst powder and the mineral material after acid leaching treatment.

10. A heavy metal adsorbent based on a waste SCR denitration catalyst, characterized in that: The heavy metal adsorbent is prepared according to the preparation method of any one of claims 1 to 9.

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