Method for preparing dual catalyst from iron-aluminum slag and prepared catalyst

Abstract

The invention provides a method for preparing double catalysts from iron-aluminum slag and a prepared catalyst, and the method comprises the following steps: carrying out alkaline leaching on the iron-aluminum slag to obtain first iron slag and a sodium metaaluminate solution; adjusting the pH value of the sodium metaaluminate solution to obtain aluminum hydroxide, and dehydrating the aluminum hydroxide to obtain dehydrated aluminum hydroxide; the method comprises the following steps: mixing and sintering rare earth carbonate defluorination waste residues, waste activated carbon residues, dehydrated aluminum hydroxide and a sintering binder to obtain a carbon-aluminum-rare earth-based ozone catalyst; the waste antiferric acid and the first iron slag are mixed and subjected to solid-liquid separation, and a heavy metal solution and second iron slag are obtained; mixing the base material and the second iron slag, and performing first calcination to obtain an iron core carrier; mixing a heavy metal solution, a dispersing agent and the iron core carrier, drying and performing secondary calcination to obtain the iron core ozone catalyst, according to the method, waste acid and waste residues generated in the wet recovery process of the lithium ion battery are comprehensively utilized, the purpose of treating waste with waste is achieved, and meanwhile the catalyst with the higher additional value can be prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste residue treatment and recovery, and relates to a method for preparing a double catalyst from iron-aluminum residue and the prepared catalyst. BACKGROUND

[0002] The iron-aluminum residue is a waste residue generated in a lithium ion battery wet recovery process, and main elements in the waste residue include iron (Fe), aluminum (Al), sulfur (S), sodium (Na), and a small amount of nickel (Ni), cobalt (Co) and manganese (Mn), which are easy to pollute the environment due to heavy metal leaching in the process of stacking. The treatment of the iron-aluminum residue needs to meet strict environmental protection standards and treatment requirements, and common resource utilization directions thereof are as follows: 1) building materials: the stabilized iron-aluminum residue can be used to prepare cement clinker, thermal insulation bricks and other building materials, and needs to meet the requirements of "Radiation Element Requirements for Building Materials" (GB6566-2010); 2) road filling material: the solidified iron-aluminum residue can be used as a road filling material or a mine backfilling material in combination with sandy soil.

[0003] However, the two resource utilization directions of the iron-aluminum residue have low added value, and cannot have very strict requirements on the percentage content of nickel, cobalt and manganese.

[0004] In summary, it is necessary to provide a new iron-aluminum residue treatment method, which can comprehensively utilize waste acid and waste residue generated in a lithium ion battery wet recovery process, achieve the purpose of waste treatment with waste, and has relatively higher added value of resource recovery products of the iron-aluminum residue. SUMMARY

[0005] The purpose of the application is to provide a method for preparing a double catalyst from iron-aluminum residue and the prepared catalyst, which can comprehensively utilize waste acid and waste residue generated in a lithium ion battery wet recovery process, achieve the purpose of waste treatment with waste, has higher compatibility for the percentage content fluctuation of nickel, cobalt and manganese in the iron-aluminum residue, can reduce the process flow of the iron-aluminum residue production in the wet recovery process, and the resource recovery product of the iron-aluminum residue is a double catalyst with higher added value.

[0006] To achieve the purpose of the application, the following technical solutions are adopted:

[0007] In a first aspect, the application provides a method for preparing a double catalyst from iron-aluminum residue, which comprises the following steps:

[0008] (1) performing alkali leaching on the iron-aluminum residue and then performing solid-liquid separation to obtain first iron residue and sodium metaaluminate solution;

[0009] (2) adjusting the pH of the sodium metaaluminate solution in step (1) and then performing solid-liquid separation to obtain aluminum hydroxide, and dehydrating the aluminum hydroxide to obtain dehydrated aluminum hydroxide;

[0010] Rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide and sintering binder are mixed and sintered to obtain carbon aluminum-rare earth-based ozone catalyst.

[0011] (3) Mix the waste antiferric acid and the first iron slag from step (1) and perform solid-liquid separation to obtain a heavy metal solution and a second iron slag.

[0012] The substrate and the second iron slag are mixed and sintered to obtain an iron core carrier;

[0013] The heavy metal solution, dispersant, and iron core support are mixed, dried, and calcined to obtain an iron core ozone catalyst.

[0014] Steps (2) and (3) are not in any particular order.

[0015] It should be noted that the rare earth carbonate defluorination waste residue refers to the defluorination waste residue obtained after defluorination using rare earth carbonates in the hydrometallurgical process, and its main component is rare earth fluorides; the waste antiferric acid refers to the waste acid during the back-extraction of iron with hydrochloric acid, which contains hydrochloric acid, iron, nickel, cobalt, manganese and zinc; the main component of the waste activated carbon residue is activated carbon that adsorbs oily substances, such as extractant P204 and other extractants.

[0016] This invention involves alkali leaching of iron-aluminum slag to obtain first iron slag and sodium aluminate solution. Firstly, the sodium aluminate solution is adjusted for pH, subjected to solid-liquid separation, and dehydrated to obtain dehydrated aluminum hydroxide. Then, rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide, and a sintering binder are mixed and sintered to obtain a carbon-aluminum-rare earth-based ozone catalyst. This process utilizes and recovers rare earth elements from the rare earth carbonate defluorination waste residue, eliminating the need for additional rare earth element addition. Simultaneously, the waste activated carbon residue is used for pore formation, thus achieving the goal of treating waste with waste and improving the utilization rate of rare metals.

[0017] On the other hand, this invention uses waste antiferric acid to mix with the first iron slag to make a slurry, and separates the heavy metal solution and the second iron slag. The second iron slag is mixed with the substrate and calcined, and then mixed with the heavy metal solution and dispersant, dried and calcined. This effectively utilizes the hydrochloric acid and iron, nickel, cobalt, manganese, zinc, etc. in the waste antiferric acid, achieving the goal of treating waste with waste and improving the utilization rate of rare metals. Therefore, this invention prepares carbon-aluminum-rare earth-based ozone catalyst and iron core ozone catalyst. These two catalysts can be used alone to degrade ozone or used in combination to degrade ozone, effectively improving the value of the resource recovery products of iron and aluminum slag.

[0018] Preferably, the solid-liquid ratio of the iron-aluminum slag and the alkaline solution (such as liquid alkali) used for alkali leaching in step (1) is 1g:(1-3)mL, for example, it can be 1g:1mL, 1g:2mL or 1g:3mL, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the alkali soaking time in step (1) is 3h-5h, for example, it can be 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the pH of the sodium aluminate solution in step (1) is adjusted to 5.5-7.5, for example, 5.5, 6, 6.5, 7 or 7.5, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the dehydration in step (2) is carried out under vacuum conditions of 80℃-100℃, for example, 80℃, 85℃, 90℃, 95℃ or 100℃, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the mass ratio of rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide and sintering binder in step (2) is 1:(2-3):(3-4):(0.1-0.5), for example, it can be 1:2.5:3:0.1, 1:2:3.5:0.2, 1:3:4:0.4 or 1:2.5:3.5:0.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the sintering temperature in step (2) is 400℃-650℃, for example, 400℃, 450℃, 500℃, 550℃, 600℃ or 650℃, and the time is 1h-2.5h, for example, 1h, 1.5h, 2h or 2.5h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the rare earth carbonate defluorination waste residue in step (2) includes cerium lanthanum carbonate defluorination waste residue.

[0025] Preferably, the carbon-aluminum-rare earth-based ozone catalyst is a carbon-aluminum-cerium-lanthanum ozone catalyst.

[0026] Preferably, the sintering binder in step (2) includes a starch-based sintering binder.

[0027] This invention uses a starch-based sintering binder, which can effectively increase the structural strength of the catalyst.

[0028] Preferably, the starch-based sintering binder includes starch derived from grains, such as corn flour and / or rice flour.

[0029] Preferably, after sintering in step (2), the material is further crushed and sieved.

[0030] Preferably, the specific surface area of ​​the carbon-aluminum-rare earth-based ozone catalyst (appearing as irregular black particles) in step (2) is ≥150 m². 2 / g, for example, could be 150m 2 / g、155m 2 / g, 160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g or 200m 2 / g, with an average particle size of 0.1mm-1mm, such as 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, and a pore size of 2nm-10nm, such as 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the pH of the mixture obtained by mixing the waste antiferric acid and the first iron slag in step (1) in step (3) is 3-4, for example, it can be 3, 3.2, 3.4, 3.6, 3.8 or 4, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the mass ratio of the substrate and the second iron slag in step (3) is 1:(4-5), for example, it can be 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the substrate in step (3) comprises clay material.

[0034] Preferably, the clay material includes argillaceous loess and / or shale.

[0035] Preferably, the mass ratio of the heavy metal solution and the dispersant in step (3) is 10:(0.1-0.5), for example, it can be 10:0.1, 10:0.2, 10:0.3, 10:0.4 or 10:0.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the solid-liquid ratio of the iron core carrier and the heavy metal solution in step (3) is 1g:(2-6)mL, for example, it can be 1g:2mL, 1g:3mL, 1g:4mL, 1g:5mL or 1g:6mL, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, in step (3), after mixing the heavy metal solution, dispersant and iron core carrier, solid-liquid separation is performed before drying.

[0038] Preferably, the dispersant in step (3) comprises dodecyltrimethylammonium bromide.

[0039] Preferably, the drying temperature in step (3) is 50℃-100℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, step (3) involves mixing the heavy metal solution, the dispersant, and the iron core carrier. This includes first mixing the heavy metal solution and the dispersant to obtain a mixture, and then immersing the iron core carrier in the mixture for a time of 2-4 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the temperature of the first calcination in step (3) is 350℃-550℃, for example, it can be 350℃, 400℃, 450℃, 500℃ or 550℃, and the time is 2h-4h, for example, it can be 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the second calcination temperature in step (3) is 400℃-600℃, for example, 400℃, 450℃, 500℃, 550℃ or 600℃, and the time is 3h-5h, for example, 3h, 3.5h, 4h, 4.5h or 5h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the iron-core ozone catalyst (appearing as spherical black particles) described in step (3) has a specific surface area ≥100 m². 2 / g, for example, could be 100m 2 / g、110m 2 / g, 120m 2 / g, 130m 2 / g, 140m 2 / g, 150m2 / g、155m 2 / g, 160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g or 200m 2 / g, with an average particle size of 2.5mm-3.5mm, such as 2.5mm, 2.7mm, 2.9mm, 3.1mm, 3.3mm or 3.5mm, and a nickel, cobalt and manganese loading of 1.0wt%-2.0wt%, such as 1.0wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt% or 2.0wt%, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] In a second aspect, the present invention provides a catalyst comprising a carbon-aluminum-rare earth-based ozone catalyst prepared by the method described in the first aspect and / or an iron-core ozone catalyst prepared by the method described in the second aspect.

[0045] Preferably, the catalyst comprises a carbon-aluminum-rare earth-based ozone catalyst and an iron-core ozone catalyst in a mass ratio of (1-5):(1-5), for example, it can be 1:1, 1:3, 1:5, 5:1 or 3:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] When the carbon-aluminum-rare earth-based ozone catalyst obtained by this invention is used alone, the ozone removal rate of the target pollutant is ≥90%, for example, 90%, 92%, 94% or 96%, and the number of cycles is ≥10, for example, 10, 11, 12 or 13 times. When the iron core ozone catalyst is used alone, the ozone removal rate of the target pollutant is ≥90%, for example, 90%, 92%, 94% or 96%, and the number of cycles is ≥10, for example, 10, 11, 12 or 13 times. When the carbon-aluminum-rare earth-based ozone catalyst and the iron core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate of the target pollutant is ≥95%, for example, 95%, 97% or 99%, and the number of cycles is ≥10, for example, 10, 11, 12 or 13 times.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] This invention utilizes rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide, and a sintering binder to mix and sinter, thus obtaining a carbon-aluminum-rare earth-based ozone catalyst. It utilizes and recovers rare earth elements from the rare earth carbonate defluorination waste residue, eliminating the need for additional rare earth element addition. Simultaneously, the waste activated carbon residue is used for pore formation, achieving the goal of treating waste with waste and improving the utilization rate of rare metals, resulting in a carbon-aluminum-rare earth-based ozone catalyst. This invention also effectively utilizes hydrochloric acid and metals such as iron, nickel, cobalt, manganese, and zinc from waste antiferric acid, achieving the goal of treating waste with waste and improving the utilization rate of rare metals, resulting in an iron-core ozone catalyst. The carbon-aluminum-rare earth-based ozone catalyst and the iron-core ozone catalyst can be used alone or in combination to degrade ozone, effectively increasing the value of the recycled iron and aluminum slag products. Attached Figure Description

[0049] Figure 1 This is a flowchart of the method described in Embodiments 1-3 of the present invention. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] Example 1

[0052] This embodiment provides a method for preparing a dual catalyst from iron-aluminum slag, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0053] (1) Iron-aluminum slag and liquid alkali were mixed at a solid-liquid ratio of 1g:1mL, leached for 3h, and filtered to obtain sodium aluminate solution and the first iron slag. The pH of the sodium aluminate solution was adjusted to 5.5 with sulfuric acid to obtain aluminum hydroxide.

[0054] (2) The aluminum hydroxide obtained in step (1) is dehydrated under vacuum at 80°C to obtain dehydrated aluminum hydroxide, which is then ground into powder to obtain dehydrated aluminum hydroxide powder.

[0055] (3) Mix the cerium lanthanum defluorination waste residue powder, waste activated carbon residue, dehydrated aluminum hydroxide powder and starch binder (specifically corn flour) in a mass ratio of 1:2:3:0.1 to obtain the first mixture, and then sinter it at 400℃ for 1 hour under nitrogen atmosphere to obtain the crude carbon aluminum-cerium lanthanum ozone catalyst.

[0056] (4) The crude carbon-aluminum-cerium-lanthanum ozone catalyst obtained in step (3) is pulverized and sieved to obtain a carbon-aluminum-cerium-lanthanum ozone catalyst. The carbon-aluminum-cerium-lanthanum ozone catalyst appears as irregular black particles with a specific surface area of ​​150 m². 2 / g, with an average particle size of 0.1mm and an internal pore size of 2nm;

[0057] (5) Mix the waste antiferric acid with the first iron slag from step (1) to make a slurry, and keep the pH value at 3.0. Filter to obtain a heavy metal solution and a second iron slag.

[0058] (6) The substrate and the second iron slag from step (5) are mixed at a dry mass ratio of 1:4 to obtain a second mixture. The second mixture is then granulated and sintered at 350°C for 2.0 h and sieved to obtain a first iron core carrier. The substrate is argillaceous loess.

[0059] (7) The heavy metal solution and dispersant in step (5) are mixed at a mass ratio of 10:0.1 to obtain a mixed solution. Then, the first iron core support in step (6) is immersed in the mixed solution for 2.0 h. After filtration, a second iron core support is obtained. The second iron core support is dried at a low temperature of 50°C and then sintered at a controlled temperature of 400°C for 3.0 h to obtain an iron core ozone catalyst. The iron core ozone catalyst appears as spherical black particles with a specific surface area of ​​100 m². 2 / g, with an average particle size of 2.5mm and a nickel-cobalt-manganese loading of 1.0wt%;

[0060] Wherein, the solid-liquid ratio of the first iron core carrier to the heavy metal solution is 1g / 2mL, and the dispersant is dodecyltrimethylammonium bromide;

[0061] When the carbon-aluminum-cerium-lanthanum ozone catalyst obtained in this embodiment is used alone, the ozone removal rate for the target pollutant is 91%, and the number of cycles is 12. When the iron core ozone catalyst is used alone, the ozone removal rate for the target pollutant is 91.5%, and the number of cycles is 12. When the carbon-aluminum-cerium-lanthanum ozone catalyst and the iron core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate for the target pollutant is 95%, and the number of cycles is 12.

[0062] Example 2

[0063] This embodiment provides a method for preparing a dual catalyst from iron-aluminum slag, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0064] (1) Iron-aluminum slag and liquid alkali were mixed at a solid-liquid ratio of 1g:2mL, leached for 4h, and filtered to obtain sodium aluminate solution and the first iron slag. The pH of the sodium aluminate solution was adjusted to 6 with sulfuric acid to obtain aluminum hydroxide.

[0065] (2) The aluminum hydroxide obtained in step (1) is dehydrated under vacuum at 90°C to obtain dehydrated aluminum hydroxide, which is then ground into powder to obtain dehydrated aluminum hydroxide powder.

[0066] (3) The cerium lanthanum carbonate defluorination waste residue powder, waste activated carbon residue, dehydrated aluminum hydroxide powder and starch binder (specifically corn flour) are mixed in a mass ratio of 1:2.5:3.5:0.2 to obtain the first mixture, and then sintered at 450℃ for 1.5h under nitrogen atmosphere to obtain the crude carbon aluminum-cerium lanthanum ozone catalyst.

[0067] (4) The crude carbon-aluminum-cerium-lanthanum ozone catalyst obtained in step (3) is pulverized and sieved to obtain a carbon-aluminum-cerium-lanthanum ozone catalyst. The carbon-aluminum-cerium-lanthanum ozone catalyst appears as irregular black particles with a specific surface area of ​​165 m². 2 / g, with an average particle size of 0.2mm and an internal pore size of 2.5nm;

[0068] (5) Mix the waste antiferric acid with the first iron slag from step (1) to make a slurry, and keep the pH value at 3.2. Filter to obtain a heavy metal solution and a second iron slag.

[0069] (6) The substrate and the second iron slag from step (5) are mixed at a dry mass ratio of 1:4.1 to obtain a second mixture. The second mixture is then granulated and sintered at 400°C for 2.5 hours and sieved to obtain a first iron core carrier. The substrate is argillaceous loess.

[0070] (7) The heavy metal solution and dispersant in step (5) are mixed at a mass ratio of 10:0.25 to obtain a mixed solution. Then, the first iron core support in step (6) is immersed in the mixed solution for 2.5 hours. After filtration, a second iron core support is obtained. The second iron core support is dried at a low temperature of 65°C and then sintered at a controlled temperature of 420°C for 4.0 hours to obtain an iron core ozone catalyst. The iron core ozone catalyst appears as spherical black particles with a specific surface area of ​​110 m². 2 / g, with an average particle size of 2.65mm and a nickel-cobalt-manganese loading of 1.2wt%;

[0071] The solid-liquid ratio of the first iron core carrier to the heavy metal solution is 1 g / 3 mL, and the dispersant is dodecyltrimethylammonium bromide.

[0072] When the carbon-aluminum-cerium-lanthanum ozone catalyst obtained in this embodiment is used alone, the ozone removal rate for the target pollutant is 92.2%, and the number of cycles is 11. When the iron core ozone catalyst is used alone, the ozone removal rate for the target pollutant is 92.8%, and the number of cycles is 11. When the carbon-aluminum-cerium-lanthanum ozone catalyst and the iron core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate for the target pollutant is 96.5%, and the number of cycles is 11.

[0073] Example 3

[0074] This embodiment provides a method for preparing a dual catalyst from iron-aluminum slag, the flowchart of which is shown below.Figure 1 As shown, it includes the following steps:

[0075] (1) Iron-aluminum slag and liquid alkali were mixed at a solid-liquid ratio of 1g:2.85mL, leached for 5h, and filtered to obtain sodium aluminate solution and the first iron slag. The pH of the sodium aluminate solution was adjusted to 7.2 with sulfuric acid to obtain aluminum hydroxide.

[0076] (2) The aluminum hydroxide obtained in step (1) is dehydrated under vacuum at 95°C to obtain dehydrated aluminum hydroxide, which is then ground into powder to obtain dehydrated aluminum hydroxide powder.

[0077] (3) The cerium lanthanum defluorination waste residue powder, waste activated carbon residue, dehydrated aluminum hydroxide powder and starch binder (specifically corn flour) are mixed in a mass ratio of 1:2.9:3.9:0.48 to obtain the first mixture, and then sintered at 650℃ for 2.4h under nitrogen atmosphere to obtain the crude carbon aluminum-cerium lanthanum ozone catalyst.

[0078] (4) The crude carbon-aluminum-cerium-lanthanum ozone catalyst obtained in step (3) is pulverized and sieved to obtain a carbon-aluminum-cerium-lanthanum ozone catalyst. The carbon-aluminum-cerium-lanthanum ozone catalyst appears as irregular black particles with a specific surface area of ​​170 m². 2 / g, with an average particle size of 0.28mm and an internal pore size of 3.8nm;

[0079] (5) Mix the waste antiferric acid with the first iron slag from step (1) to make a slurry, and keep the pH value at 4. Filter to obtain a heavy metal solution and a second iron slag.

[0080] (6) The substrate and the second iron slag from step (5) are mixed at a dry mass ratio of 1:4.8 to obtain a second mixture. The second mixture is then granulated and sintered at 450°C for 3.0 h and sieved to obtain a first iron core carrier. The substrate is argillaceous loess.

[0081] (7) The heavy metal solution and dispersant in step (5) are mixed at a mass ratio of 10:0.45 to obtain a mixed solution. Then, the first iron core support in step (6) is immersed in the mixed solution for 3.5 hours. After filtration, a second iron core support is obtained. The second iron core support is dried at a low temperature of 100°C and then sintered at a controlled temperature of 600°C for 4.5 hours to obtain an iron core ozone catalyst. The iron core ozone catalyst appears as spherical black particles with a specific surface area of ​​109 m². 2 / g, with an average particle size of 2.6mm and a nickel-cobalt-manganese loading of 1.21wt%;

[0082] The solid-liquid ratio of the first iron core carrier to the heavy metal solution is 1 g / 4 mL, and the dispersant is dodecyltrimethylammonium bromide.

[0083] When the carbon-aluminum-cerium-lanthanum ozone catalyst obtained in this embodiment is used alone, the ozone removal rate for the target pollutant is 93.4%, and the number of cycles is 10. When the iron core ozone catalyst is used alone, the ozone removal rate for the target pollutant is 93.4%, and the number of cycles is 10. When the carbon-aluminum-cerium-lanthanum ozone catalyst and the iron core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate for the target pollutant is 95.8%, and the number of cycles is 10.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing a dual catalyst from iron-aluminum slag. Except for step (3), in which cerium lanthanum carbonate defluorination waste powder is not added, the method is the same as in Example 1.

[0086] The carbon-aluminum ozone catalyst obtained in step (4) of this comparative example appears as irregular black particles with a specific surface area of ​​159.75 m². 2 / g, with an average particle size of 0.22mm and an internal pore size of 2.54nm;

[0087] When the carbon-aluminum ozone catalyst obtained in this comparative example is used alone, the ozone removal rate for the target pollutant is 75%, and the number of cycles is 6. When the carbon-aluminum ozone catalyst and the iron core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate for the target pollutant is 91.5%, and the number of cycles is 8.

[0088] Comparative Example 2

[0089] This comparative example provides a method for preparing a dual catalyst from iron-aluminum slag. The method is the same as in Example 1 except that the waste antiferric acid in step (5) is replaced with hydrochloric acid, mixed with the first iron slag in step (1) to form a slurry, and the pH value is kept at 3.0.

[0090] The iron-core ozone catalyst obtained in this comparative example appears as spherical black particles with a specific surface area of ​​112 m². 2 / g, with an average particle size of 2.65mm and a nickel-cobalt-manganese loading of 0.97wt%;

[0091] When the iron-core ozone catalyst obtained in this comparative example is used alone, the ozone removal rate for the target pollutant is 89%, and the number of cycles is 9. When the carbon-aluminum-cerium-lanthanum ozone catalyst and the iron-core ozone catalyst are mixed at a mass ratio of 1:1, the ozone removal rate for the target pollutant is 92.2%, and the number of cycles is 9.

[0092] The application methods of catalysts are as follows:

[0093] (1) In the ozone catalytic tower, the catalysts prepared in the above examples and comparative examples are filled in proportion; the phenol-containing wastewater to be treated (the initial concentration of phenol is 100 mg / L) is loaded into the water tank, the circulating water pump is started, and the wastewater circulates between the water tank and the ozone catalytic tower. The ozone generator is started to produce a certain concentration of ozone (in the range of 50 to 100 mg / L, here it is 75 mg / L). Then, after 30 minutes, the concentration of phenol in the wastewater is sampled and tested. The removal rate of pollutants by ozone within 30 minutes is calculated by the concentration of phenol in the liquid before and after the reaction. Among them, the removal rate of target pollutant by ozone % = (initial concentration of pollutant - concentration of pollutant after reaction) / initial concentration of pollutant × 100%, where pollutant refers to phenol.

[0094] (2) Repeat step (1) above to obtain the number of times the catalyst is recycled. The number of times the catalyst is recycled refers to the number of times the catalyst is used when the ozone removal rate of the target pollutant is above 75%.

[0095] In summary, as shown in Examples 1-4 and Comparative Example 1, the present invention, by adding rare earth carbonate defluorination waste residue, not only achieves waste-to-waste treatment but also recovers rare earth elements from the rare earth carbonate defluorination waste residue. Introducing rare earth elements into the catalyst improves its performance. As shown in Examples 1-4 and Comparative Example 2, the catalyst prepared by the present invention using waste antiferric acid still possesses superior catalytic performance compared to that prepared using hydrochloric acid. Thus, the present invention can achieve waste-to-waste treatment, effectively utilize hydrochloric acid and metals in waste antiferric acid, and improve the utilization rate of rare metals.

[0096] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a dual catalyst from iron-aluminum slag, characterized in that, The method includes the following steps: (1) After alkaline leaching, the iron-aluminum slag is separated into solid and liquid to obtain the first iron slag and sodium aluminate solution. (2) After adjusting the pH of the sodium aluminate solution in step (1), solid-liquid separation is performed to obtain aluminum hydroxide. The aluminum hydroxide is then dehydrated to obtain dehydrated aluminum hydroxide. Rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide and sintering binder are mixed and sintered to obtain carbon aluminum-rare earth-based ozone catalyst. (3) Mix the waste antiferric acid and the first iron slag from step (1) and perform solid-liquid separation to obtain a heavy metal solution and a second iron slag. The substrate and the second iron slag are mixed and subjected to a first calcination to obtain an iron core carrier; The heavy metal solution, dispersant and iron core support are mixed, dried and then calcined to obtain an iron core ozone catalyst. Steps (2) and (3) are not in any particular order.

2. The method according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the iron-aluminum slag to the alkaline solution used for alkali leaching is 1g:(1-3)mL; Preferably, the alkali soaking time in step (1) is 3-5 hours; Preferably, the pH of the sodium aluminate solution in step (1) is adjusted to 5.5-7.

5.

3. The method according to claim 1 or 2, characterized in that, The dehydration in step (2) is carried out under vacuum conditions at 80℃-100℃; Preferably, the mass ratio of rare earth carbonate defluorination waste residue, waste activated carbon residue, dehydrated aluminum hydroxide and sintering binder in step (2) is 1:(2-3):(3-4):(0.1-0.5); Preferably, the sintering temperature in step (2) is 400℃-650℃ and the time is 1h-2.5h.

4. The method according to any one of claims 1-3, characterized in that, The rare earth carbonate defluorination waste residue in step (2) includes cerium lanthanum carbonate defluorination waste residue; Preferably, the sintering binder in step (2) includes a starch-based sintering binder; Preferably, the starch-based sintering binder includes corn flour and / or rice flour.

5. The method according to any one of claims 1-4, characterized in that, After sintering in step (2), the material was further crushed and sieved. Preferably, the specific surface area of ​​the carbon-aluminum-rare earth-based ozone catalyst in step (2) is ≥150 m². 2 / g, with an average particle size of 0.1mm-1mm and a pore size of 2nm-10nm.

6. The method according to any one of claims 1-5, characterized in that, The pH of the mixture obtained by mixing the waste antiferric acid and the first iron slag in step (1) in step (3) is 3-4; Preferably, the mass ratio of the substrate and the second iron slag in step (3) is 1:(4-5); Preferably, the substrate in step (3) comprises clay material; Preferably, the clay material includes argillaceous loess and / or shale.

7. The method according to any one of claims 1-6, characterized in that, The mass ratio of the heavy metal solution to the dispersant in step (3) is 10:(0.1-0.5); Preferably, the solid-liquid ratio of the iron core carrier and the heavy metal solution in step (3) is 1 g:(2-6) mL; Preferably, in step (3), after mixing the heavy metal solution, dispersant and iron core carrier, solid-liquid separation is performed before drying.

8. The method according to any one of claims 1-7, characterized in that, The dispersant in step (3) includes dodecyltrimethylammonium bromide; Preferably, step (3) of mixing the heavy metal solution, the dispersant and the iron core carrier includes first mixing the heavy metal solution and the dispersant to obtain a mixture, and then immersing the iron core carrier in the mixture for 2-4 hours. Preferably, in step (3), the temperature of the first calcination is 350℃-550℃, and the time is 2h-4h; Preferably, in step (3), the second calcination temperature is 400℃-600℃ and the time is 3h-5h.

9. The method according to any one of claims 1-8, characterized in that, The specific surface area of ​​the iron-core ozone catalyst in step (3) is ≥100 m². 2 / g, with an average particle size of 2.5mm-3.5mm and a nickel-cobalt-manganese loading of 1.0wt%-2.0wt%.

10. A catalyst, characterized in that, The catalyst includes a carbon-aluminum-rare earth-based ozone catalyst prepared by any one of the methods described in claims 1-9 and / or an iron-core ozone catalyst prepared by any one of the methods described in claims 1-9.

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