Preparation method and application of modified sedimentation tank waste residues

Abstract

The invention relates to the technical field of concrete, and discloses a modified sedimentation tank waste residue preparation method and application thereof.The preparation method comprises the steps that sedimentation tank waste residues, steel slag, metakaolin, red mud, nickel slag and copper slag are mixed and stirred to be uniform, mixed waste residues are obtained, an alkaline solution is added, and after stirring and soaking are conducted for 2-3 h, a waste residue impregnated material is obtained; adding an additive into the waste residue impregnated material, and then carrying out wet grinding to obtain waste residue slurry; and drying the waste residue slurry, spraying the modified solution and curing to obtain the modified sedimentation tank waste residue. According to the invention, industrial solid wastes such as sedimentation tank waste residues and steel slag are used as raw materials, and a high-performance material with a graded porous structure and amino and hydroxyl functional groups is obtained through alkaline leaching activation, wet grinding and modification technologies, so that the problem of accumulation and landfill of traditional sedimentation tank waste residues is solved, and the sedimentation tank waste residues are endowed with high adsorption activity and gelling capacity.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for preparing modified sedimentation tank waste residue and its application. Background Technology Currently, the commonly used wastewater recycling system in concrete mixing plants involves wastewater from the rinsing tank passing through a sand and gravel separator before entering a sedimentation tank. After sedimentation, upper layer recycled water and sedimentation tank sludge are formed. The upper layer recycled water can be used for production and equipment rinsing, while the sludge settled to the bottom is currently mostly disposed of through landfill.

[0002] The main components of sedimentation tank waste are unhydrated cementitious materials and hydration products, which are alkaline. Traditional landfill methods for treating sedimentation tank waste pollute the environment and waste resources. Sedimentation tank waste often has a porous structure and is coated with hydration products such as CSH gel, resulting in high water absorption and weak cementing ability. Direct use as a mineral admixture affects the workability, mechanical properties, and durability of concrete. To address this issue, the main current treatment method for sedimentation tank waste includes using the waste from mixing plants as raw material to prepare artificial aggregates. However, the prepared artificial aggregates have low strength, and their properties differ significantly from natural aggregates when applied to concrete, limiting their use to low-grade concrete and resulting in low utilization rates.

[0003] At present, the development of concrete mixing plants towards green and low-carbon directions is inevitable. How to solve the problem of excessive accumulation of waste in sedimentation tanks, promote the resource utilization and high-value application of sedimentation tank waste, and reduce the carbon emissions of concrete has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing modified sedimentation tank waste residue and its application, which solves the problems of low cementitious activity of existing sedimentation tank waste residue, the impact of direct utilization on concrete performance, high energy consumption and limited utilization rate of traditional treatment methods, and the difficulty in simultaneously imparting high strength, excellent permeability and heavy metal adsorption function to concrete, thereby achieving the effects of reducing carbon emissions and enhancing the comprehensive performance and environmental benefits of concrete.

[0005] Based on the above concept, the technical solution adopted by this invention is as follows: According to a first aspect of the present invention, a method for preparing modified sedimentation tank waste residue is provided, comprising the following steps: S1. Mix the sedimentation tank waste residue, steel slag, metakaolin, red mud, nickel slag and copper slag evenly to obtain mixed waste residue. Add alkaline solution, stir and soak for 2-3 hours to obtain waste residue impregnation material. S2. Additives are added to the waste residue impregnated material in step S1, and then wet grinding is performed to obtain waste residue slurry; S3. The waste residue slurry from step S2 is dried, sprayed with a modification solution, and solidified to obtain modified sedimentation tank waste residue.

[0006] In some embodiments, the mass ratio of the sedimentation tank waste residue, steel slag, metakaolin, red mud, nickel slag, and copper slag in step S1 is (55~65):(10~15):(6~10):(5~8):(4~6):(3~5).

[0007] In some embodiments, the total solute concentration of the alkaline solution is 8-12 wt%; the mass ratio of the alkaline solution to the mixed waste residue is 1.5:1 to 2.5:1.

[0008] In some embodiments, the alkaline solution includes sodium hydroxide, sodium dodecyl sulfate, and sodium silicate; The mass ratio of sodium dodecyl sulfate to sodium hydroxide is 0.0001:1 to 0.0005:1; The mass ratio of sodium silicate to sodium hydroxide is 0.15:1 to 0.20:1.

[0009] In some embodiments, the additives in step S2 include nano-silica and zeolite powder; The mass fraction of nano-silica in the waste residue slurry is 1%-2.5%; The mass fraction of zeolite powder in the waste residue slurry is 6%-10%.

[0010] In some embodiments, the modified solution comprises 3-aminopropyltriethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane; The total silane concentration of the modified solution is 2-5 wt%; The mass ratio of 3-aminopropyltriethoxysilane to 3-glycidyl etheroxypropyltrimethoxysilane is 1:1 to 2:1; The mass ratio of the modified solution to the dried waste residue slurry is 0.02:1 to 0.03:1.

[0011] According to a second aspect of the present invention, an application of modified sedimentation tank waste residue is provided for the preparation of ecological filter media, modified polypropylene fibers, and low-carbon ecological permeable concrete.

[0012] According to a third aspect of the present invention, a method for preparing ecological filter media is provided, comprising the following steps: S41a. The modified sedimentation tank waste residue, cement, quartz tailings and water are mixed evenly and then poured into a granulator. After being cut by a cutting device, an ecological filter material blank is obtained. S41b. Ecological filter media is obtained by curing the ecological filter media blank under standard curing conditions for 24 hours.

[0013] According to a fourth aspect of the present invention, a method for preparing modified polypropylene fibers is provided, comprising the following steps: S42a. Premix the polypropylene granules and the modified sedimentation tank waste in a high-speed mixer for 5-10 minutes to obtain a polypropylene granule premix. S42b: Modified polypropylene fibers are obtained by melt blending, extrusion granulation, spinning, and crushing of polypropylene granule premix.

[0014] According to a fifth aspect of the present invention, a low-carbon ecological permeable concrete is provided, comprising the following components in parts by weight: The mixture consists of 120-150 parts modified sedimentation tank waste residue, 1600-1850 parts ecological filter media, 10-12 parts modified polypropylene fiber, 130-150 parts cement, 30-50 parts silica fume, 60-80 parts mineral powder, and 110-150 parts water.

[0015] The beneficial effects of this invention are as follows: 1. This invention uses industrial solid waste such as sedimentation tank slag and steel slag as raw materials. Through alkaline leaching activation, wet grinding and modification technology, a high-performance material with hierarchical porous structure and amino and hydroxyl functional groups is obtained. This not only solves the problem of traditional sedimentation tank slag accumulation and landfill, but also endows the sedimentation tank slag with high adsorption activity and gelling ability. In addition, nano-silica and zeolite powder are added during the wet grinding process to construct a micro-mesoporous hierarchical structure, increase the specific surface area, and use the modification solution to graft amino and hydroxyl functional groups and solidify them to form a hybrid membrane to fix the amino and hydroxyl functional groups, thereby enhancing the chemical adsorption capacity of sedimentation tank slag for heavy metals. The Cd removal rate reaches 99.70% and the Pb removal rate reaches 99.89%.

[0016] 2. This invention utilizes the added alkaline solution to promote the dispersion of sedimentation tank waste residue and steel slag, remove flocculant components, destroy the activated components of silicon / aluminum mineral structure, and soften hard components such as steel slag, nickel slag, and copper slag. This improves the cementitious activity and grinding efficiency of sedimentation tank waste residue and dissolves f-CaO and f-MgO, preventing expansion and cracking in the later stage. Furthermore, the low-carbon ecological permeable concrete prepared using modified sedimentation tank waste residue achieves a compressive strength of 30.6 MPa, a cadmium removal rate of 82.68%, and a lead removal rate of 84.95%. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation process of modified sedimentation tank waste residue according to the present invention; Figure 2 This is a flowchart illustrating the preparation process of an eco-friendly filter material according to the present invention. Figure 3 This is a flowchart illustrating the preparation process of a modified polypropylene fiber according to the present invention. Detailed Implementation

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0019] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise defined, the technical or scientific terms used in this application should be understood in their ordinary sense by one of ordinary skill in the art to which this invention pertains. The words “a” or “one” and similar terms used in this application specification and claims do not indicate a limitation of quantity, but rather indicate the presence of at least one. “A plurality” means two or more. The words “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” covers the element or object listed following “comprising” or “including” and its equivalents, and does not exclude other elements or objects. The words “connected” or “linked” and similar terms are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect. The words “above” and / or “below” and similar terms are for ease of description only and are not limited to a location or spatial orientation. The singular forms “a,” “the,” and “the” used in this application specification and appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0020] The technical concept of this invention includes: Currently, the commonly used wastewater recycling system in concrete mixing plants involves wastewater from the rinsing tank passing through a sand and gravel separator before entering a sedimentation tank. After sedimentation, a supernatant of recycled water and sedimentation tank sludge are formed. The supernatant recycled water can be used for production and equipment rinsing, while the sludge settled to the bottom is currently mostly disposed of through landfill. The main methods for treating sedimentation tank sludge currently include: (1) Preparation of non-fired bricks and curing agent; This treatment method involves a complicated production process and requires high-energy-consuming equipment, resulting in high energy consumption and high carbon emissions; (2) Preparation of pump lubricant; Although this treatment method has a simple production process, it has a low utilization rate and cannot achieve large-scale recycling and reuse of sedimentation tank waste. (3) After mechanical grinding, it is used as a mineral admixture; the performance improvement of the sedimentation tank waste residue after grinding is limited, the application range is narrow, and the utilization rate is low. (4) Using the waste residue from the mixing plant as raw material to prepare artificial aggregate; the artificial aggregate prepared by this method has low strength and its performance is very different from that of natural aggregate when applied to concrete. It can only be used in low-grade concrete and has a low utilization rate.

[0021] This invention addresses the problems of low strength and significant performance differences compared to natural aggregates in the preparation of artificial aggregates from sedimentation tank waste. First, it utilizes a specifically formulated alkaline solution to synergistically activate and soften various industrial solid wastes (sedimentation tank waste, steel slag, etc.), disrupting their inert structures and enhancing their gelling activity and grindability. Second, during wet grinding, nano-silica and zeolite powder are introduced. Zeolite powder acts as microcrystalline seeds, providing a microporous framework to induce directional crystallization, while nano-silica acts as a mesoporous template to prevent disordered stacking. The synergistic effect of these two materials constructs a hierarchical porous structure, increasing specific surface area and active sites. Then, a modified solution is prepared by mixing 3-aminopropyltriethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane for surface modification. The modified solution undergoes hydrolytic polymerization within the constructed hierarchical porous structure, achieving efficient grafting of amino and hydroxyl groups. Finally, the modified solution is induced to fully hydrolyze and condense through solidification treatment to form a robust hybrid membrane that fixes amino and hydroxyl groups, thereby improving the heavy metal adsorption performance and gelation activity of the modified sedimentation tank waste residue. This simultaneously endows the modified product with excellent mechanical property enhancement and efficient heavy metal chemical adsorption capacity.

[0022] This invention successfully transforms low-value sedimentation tank waste into a high-performance, multifunctional material through the aforementioned integrated modification process of "alkali activation-structure construction-functional modification." This not only solves the problem of excessive accumulation of sedimentation tank waste but also enables its high-value-added applications in high-end building materials such as ecological filter media, modified fibers, and low-carbon permeable concrete, providing a pathway for the green and low-carbon transformation of the concrete industry and the resource utilization of solid waste.

[0023] The following describes in detail, with reference to embodiments and comparative examples, a method for preparing modified sedimentation tank waste residue provided in this application and its application.

[0024] Example 1 S1. Take 60 parts of sedimentation tank waste residue, 12 parts of steel slag, 10 parts of metakaolin, 8 parts of red mud, 5 parts of nickel slag, and 5 parts of copper slag, mix them evenly to obtain mixed waste residue, and add an alkaline solution with a total solute concentration of 10wt% prepared by mixing 16.4 parts of sodium hydroxide, 0.6 parts of sodium dodecyl sulfate, and 3 parts of sodium silicate. The mass ratio of alkaline solution to mixed waste residue is 2:1; stir and soak for 2.5 hours to obtain waste residue impregnated material.

[0025] S2. Add 6 parts of nano silica and 18 parts of zeolite powder (the nano silica and zeolite powder are pre-dispersed using ultrasound or a homogenizer before being added, wherein the nano silica particle size is 5-50nm and the zeolite powder particle size is 500nm-5μm) to the impregnation material from step S1 and perform wet grinding for 1.5h to obtain waste residue slurry. S3. Dry the slurry from step S2, and spray it with a modification solution with a total silane concentration of 5wt%, prepared by 0.096 parts of KH550 (3-aminopropyltriethoxysilane) and 0.048 parts of KH570 (3-glycidyl etheroxypropyltrimethoxysilane). The mass ratio of the modification solution to the dried waste slurry is 0.02:1. After stirring evenly and letting it stand for 24 hours, it is cured at 110℃ for 2.5 hours to obtain the modified sedimentation tank waste slurry.

[0026] Example 2 S1. Take 65 parts of sedimentation tank waste residue, 14 parts of steel slag, 6 parts of metakaolin, 5 parts of red mud, 6 parts of nickel slag, and 4 parts of copper slag, mix them evenly to obtain mixed waste residue, and add an alkaline solution with a total solute concentration of 8wt% prepared by mixing 9 parts of sodium hydroxide, 0.6 parts of sodium dodecyl sulfate, and 2.4 parts of sodium silicate. The mass ratio of alkaline solution to mixed waste residue is 1.5:1; stir and soak for 2 hours to obtain waste residue impregnated material; S2. Add 5 parts of nano silica and 17.5 parts of zeolite powder (the nano silica and zeolite powder are pre-dispersed using ultrasound or a homogenizer before being added, wherein the nano silica particle size is 5-50nm and the zeolite powder particle size is 500nm-5μm) to the impregnation material from step S1 and perform wet grinding for 2 hours to obtain waste residue slurry. S3. Dry the slurry from step S2, spray it with a modification solution with a total silane concentration of 3wt% prepared by 0.054 parts KH550 and 0.027 parts KH570, the mass ratio of the modification solution to the dried waste slurry is 0.02:1, stir evenly and let stand for 24 hours, then solidify at 105℃ for 2 hours to obtain modified sedimentation tank waste slurry.

[0027] Comparative Example 1 Everything else is the same as in Example 1, except that: In step S1, no alkaline solution is added, but the same mass of water is added, and the mixture is stirred and soaked for 2.5 hours to obtain the waste residue impregnated material.

[0028] Comparative Example 2 Everything else is the same as in Example 1, except that: In step S2, wet grinding does not involve adding nano-silica, but instead involves adding 24 parts of zeolite powder.

[0029] Comparative Example 3 Everything else is the same as in Example 1, except that: The modified solution was not sprayed in step S3.

[0030] Comparative Example 4 Everything else is the same as in Example 1, except that: Curing was not performed in step S3. Comparative Example 5 The sedimentation tank waste in this comparative example was not modified and was prepared by wet grinding and drying using conventional techniques.

[0031] According to GB / T51003-2014 "Technical Specification for Application of Mineral Admixtures", the modified sedimentation tank waste prepared in the examples and comparative examples was added to cement mortar at a dosage of 30% of the cement composition. The strength of the cement mortar specimens was tested according to GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". The stability of the modified sedimentation tank waste was tested according to GB / T1346-2011 "Test Method for Standard Consistency Water Requirement, Setting Time and Soundness of Cement". The test results are shown in Table 1.

[0032] The adsorption effect of the modified sedimentation tank waste residue in the example and comparative examples was tested using an average total cadmium concentration of 100 mg / L and an average total lead concentration of 500 mg / L in the influent. The test results are shown in Table 2.

[0033] Table 1 Performance test results of modified sedimentation tank waste residue

[0034] Table 2. Heavy metal adsorption results of waste residue from modified sedimentation tank.

[0035] As can be seen from Tables 1 and 2, compared with the unmodified sedimentation tank waste residue of Comparative Example 5, the modified sedimentation tank waste residue prepared in Examples 1 and 2 of the present invention has excellent mechanical properties and heavy metal adsorption properties.

[0036] By comparing Example 1 and Comparative Example 1, it can be found that the mechanical properties and heavy metal adsorption capacity of the modified sedimentation tank waste residue prepared in Comparative Example 1, which was not stirred and soaked in alkaline solution, showed a significant decrease. This indicates that stirring and soaking in alkaline solution can improve the mechanical properties and heavy metal adsorption performance of sedimentation tank waste residue.

[0037] By comparing Example 1 and Comparative Example 2, it can be found that without the addition of nano-silica in the wet grinding process of Comparative Example 2, the mechanical properties and heavy metal adsorption capacity of the modified sedimentation tank sludge prepared by the process are significantly reduced. This indicates that the addition of nano-silica and zeolite powder to construct a hierarchical porous structure in the wet grinding process can improve the mechanical properties and heavy metal adsorption performance of the sedimentation tank sludge.

[0038] By comparing Example 1 and Comparative Example 3, it can be found that the mechanical properties and heavy metal adsorption capacity of the modified sedimentation tank sludge prepared in Comparative Example 3 without spraying the modification solution are significantly reduced, indicating that spraying the modification solution can improve the mechanical properties and heavy metal adsorption performance of the sedimentation tank sludge.

[0039] By comparing Example 1 and Comparative Example 4, it can be found that Comparative Example 4, which was not cured after spraying the modified solution, showed a significant decrease in the mechanical properties and heavy metal adsorption capacity of the prepared modified sedimentation tank waste residue. This indicates that curing after spraying the modified solution can improve the mechanical properties and heavy metal adsorption performance of the sedimentation tank waste residue.

[0040] Example 3 S41a. Take 75 parts of the modified sedimentation tank waste residue, 6 parts of cement, 10 parts of quartz tailings and 9 parts of water from Example 1, mix them evenly and pour them into a granulator. After passing through a cutting device, form a spherical ecological filter material blank with a particle size of 3-10mm.

[0041] S41b: The ecological filter media blank from step S41a is cured under standard curing conditions for 24 hours to obtain the ecological filter media.

[0042] Example 4 S42a. Take 20 parts of the modified sedimentation tank waste residue from Example 1 and 80 parts of polypropylene particles, and premix them in a high-speed mixer for 10 minutes to obtain a polypropylene particle premix.

[0043] S42b: Polypropylene granular premix is ​​melt-blended at 190℃, granulated by twin-screw extrusion, and then fed into a melt spinning mill. The spinneret temperature is controlled at 200℃, the chamber temperature at 205℃, and the spinning speed at 400m / min. The fibers are sheared and broken to 3-5mm to obtain modified polypropylene fibers.

[0044] Example 5 This embodiment provides a low-carbon ecological permeable concrete, comprising the following raw materials by weight: 130 parts cement, 120 parts modified sedimentation tank waste from Example 1, 40 parts silica fume, 60 parts mineral powder, 1850 parts ecological filter material from Example 3, 145 parts water, and 10 parts modified polypropylene fiber from Example 4.

[0045] The preparation method of low-carbon ecological permeable concrete in this embodiment includes the following steps: 1) Weigh each component according to its weight percentage; 2) Stir the ecological filter media, modified polypropylene fiber, and 1 / 2 water for 90-120 seconds; 3) Add cement, modified sedimentation tank waste residue, silica fume, mineral powder and 1 / 4 water and continue stirring for 120-150 seconds; 4) Add the remaining 1 / 4 water and continue stirring for 120-150 seconds to obtain low-carbon ecological permeable concrete.

[0046] Comparative Example 6 Everything else is the same as in Example 5, except that: The ecological filter media of Example 5 was replaced with pebbles of the same size.

[0047] Comparative Example 7 Everything else is the same as in Example 5, except that: Ordinary polypropylene fibers were used instead of the modified polypropylene fibers in Example 5.

[0048] The performance indicators of the low-carbon ecological permeable concrete in Example 5, Comparative Example 6, and Comparative Example 7, including compressive strength, permeability coefficient, and vibration spread, were tested. The test results are shown in Table 3.

[0049] A 5 ppm solution of cadmium and lead with a pH of 3 was prepared, and the heavy metal adsorption performance of the low-carbon ecological permeable concrete prepared in Example 5, Comparative Example 6, and Comparative Example 7 was tested. The test results are shown in Table 4.

[0050] Table 3 Test results of low-carbon ecological permeable concrete

[0051] Table 4. Heavy metal adsorption results of low-carbon ecological permeable concrete

[0052] As can be seen from Tables 3 and 4, the low-carbon ecological permeable concrete prepared by using ecological filter material and modified polypropylene fiber in Example 5 has a 28-day compressive strength of 30.6 MPa, a permeability coefficient of K6, a vibration spread of 245 mm, and a removal rate of heavy metals cadmium and lead of over 82%.

[0053] By comparing Example 5 and Comparative Example 6, it can be found that the low-carbon ecological permeable concrete prepared with the ecological filter material of the present invention has better compressive strength, permeability coefficient, vibration expansion and heavy metal removal rate than the permeable concrete prepared with stones of the same particle size. This shows that the ecological filter material of the present invention can be used to prepare low-carbon ecological permeable concrete with better workability, mechanical properties, permeability and heavy metal adsorption effect.

[0054] By comparing Example 5 and Comparative Example 7, it can be found that the low-carbon ecological permeable concrete prepared with the modified polypropylene fiber of the present invention has better compressive strength, permeability coefficient, vibration expansion and heavy metal removal rate than the permeable concrete prepared with ordinary polypropylene fiber. This shows that the modified polypropylene fiber of the present invention can be used to prepare low-carbon ecological permeable concrete with better workability, mechanical properties, permeability and heavy metal adsorption effect.

[0055] Specific principles: This invention improves the dispersibility of sedimentation tank waste residue and steel slag by adding sodium dodecyl sulfate to an alkaline solution, thereby removing the flocculant. In the alkaline environment composed of sodium hydroxide and sodium silicate, the activated components of the silicon / aluminum mineral structure in the sedimentation tank waste residue and steel slag are destroyed and softened, thereby enhancing the gelling activity and wet grinding efficiency of the sedimentation tank waste residue and steel slag, increasing the number of active sites, improving the adsorption capacity for heavy metals, and accelerating the digestion of f-CaO and f-MgO, thus preventing expansion and cracking in the later stages.

[0056] Nano-silica and zeolite powder are added during wet grinding. Zeolite powder acts as a microcrystalline seed, providing a microporous framework to induce directional crystallization, while nano-silica acts as a mesoporous template to prevent disordered stacking. The two work synergistically to construct a hierarchical porous structure, increasing the specific surface area and active sites. After drying, a modified solution prepared by 3-aminopropyltriethoxysilane (KH550) and 3-glycidyl etheroxypropyltrimethoxysilane (KH570) is sprayed on. Hydrolysis and polymerization occur in the constructed hierarchical porous structure, achieving efficient grafting of amino and hydroxyl groups. After curing, the silane coupling agent is fully hydrolyzed and condensed to form a robust hybrid membrane that fixes the amino and hydroxyl groups, greatly improving the heavy metal adsorption performance and gelling activity of the modified sedimentation tank waste residue.

[0057] This invention incorporates quartz tailings during the preparation of ecological filter media. The hard quartz tailings form the framework of the ecological filter media. By utilizing the cementitious activity of cement and modified sedimentation tank waste residue, and combining it with standard curing for 24 hours, the prepared ecological filter media exhibits excellent crushing resistance. At the same time, the introduction of the hierarchical porous structure and amino and hydroxyl functional groups of the modified sedimentation tank waste residue, and the formation of a hybrid membrane to fix active sites, endows the ecological filter media with excellent heavy metal adsorption performance.

[0058] This invention utilizes a high-speed mixer to premix modified sedimentation tank waste residue to uniformly adhere it to the surface of polypropylene particles; the modified sedimentation tank waste residue is modified by its hierarchical porous structure and amino and hydroxyl functional groups to improve the adsorption capacity of heavy metals by modified polypropylene fibers and the bonding capacity between modified polypropylene fibers and concrete matrix.

[0059] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. The invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0060] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for preparing modified sedimentation tank waste residue, characterized in that, Includes the following steps: S1. Mix the sedimentation tank waste residue, steel slag, metakaolin, red mud, nickel slag and copper slag evenly to obtain mixed waste residue. Add alkaline solution, stir and soak for 2-3 hours to obtain waste residue impregnation material. S2. Additives are added to the waste residue impregnated material in step S1, and then wet grinding is performed to obtain waste residue slurry; S3. The waste residue slurry from step S2 is dried, sprayed with a modification solution, and solidified to obtain modified sedimentation tank waste residue.

2. The method for preparing modified sedimentation tank waste residue according to claim 1, characterized in that, The mass ratio of the sedimentation tank waste residue, steel slag, metakaolin, red mud, nickel slag and copper slag in step S1 is (55~65):(10~15):(6~10):(5~8):(4~6):(3~5).

3. The method for preparing modified sedimentation tank waste residue according to claim 1, characterized in that, The total solute concentration of the alkaline solution is 8-12 wt%; the mass ratio of the alkaline solution to the mixed waste residue is 1.5:1 to 2.5:

1.

4. The method for preparing modified sedimentation tank waste residue according to claim 3, characterized in that, The alkaline solution includes sodium hydroxide, sodium dodecyl sulfate, and sodium silicate; The mass ratio of sodium dodecyl sulfate to sodium hydroxide is 0.0001:1 to 0.0005:1; The mass ratio of sodium silicate to sodium hydroxide is 0.15:1 to 0.20:

1.

5. The method for preparing modified sedimentation tank waste residue according to claim 1, characterized in that, The additives mentioned in step S2 include nano-silica and zeolite powder; The mass fraction of nano-silica in the waste residue slurry is 1%-2.5%; The mass fraction of zeolite powder in the waste residue slurry is 6%-10%.

6. The method for preparing modified sedimentation tank waste residue according to claim 1, characterized in that, The modified solution comprises 3-aminopropyltriethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane; The total silane concentration of the modified solution is 2-5 wt%; The mass ratio of 3-aminopropyltriethoxysilane to 3-glycidyl etheroxypropyltrimethoxysilane is 1:1 to 2:1; The mass ratio of the modified solution to the dried waste residue slurry is 0.02:1 to 0.03:

1.

7. A modified sedimentation tank waste residue prepared by the method described in claims 1-6, characterized in that, It is used in the preparation of ecological filter media, modified polypropylene fibers, and low-carbon ecological permeable concrete.

8. The application of the modified sedimentation tank waste residue according to claim 7, characterized in that, The preparation of the ecological filter material includes the following steps: S41a. The modified sedimentation tank waste residue, cement, quartz tailings and water are mixed evenly and then poured into a granulator. After being cut by a cutting device, an ecological filter material blank is obtained. S41b. Ecological filter media is obtained by curing the ecological filter media blank under standard curing conditions for 24 hours.

9. The application of the modified sedimentation tank waste residue according to claim 7, characterized in that, The preparation of modified polypropylene fibers includes the following steps: S42a. Premix the polypropylene granules and the modified sedimentation tank waste in a high-speed mixer for 5-10 minutes to obtain a polypropylene granule premix. S42b: Modified polypropylene fibers are obtained by melt blending, extrusion granulation, spinning, and crushing of polypropylene granule premix.

10. The application of the modified sedimentation tank waste residue according to claim 7, characterized in that, The low-carbon ecological permeable concrete comprises the following components in parts by weight: The mixture consists of 120-150 parts modified sedimentation tank waste residue, 1600-1850 parts ecological filter media, 10-12 parts modified polypropylene fiber, 130-150 parts cement, 30-50 parts silica fume, 60-80 parts mineral powder, and 110-150 parts water.

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