Magnetic modified fly ash-based environmental mineral repair material and preparation method thereof

Abstract

The application discloses a kind of magnetic modified fly ash-based environmental mineral repair materials and preparation method thereof, belong to environmental functional materials and industrial solid waste resource utilization technical field, aim at solving the problem of primary fly ash adsorption capacity limited, powder is difficult to recover after use and easy to cause secondary pollution.The repair material takes fly ash as matrix carrier, is made of fly ash 60-80 parts, magnetic iron source 15-30 parts, mineral binder 5-15 parts, pore forming agent 1-5 parts by weight fraction, material particle size is 0.15-1.0mm, saturation magnetization is 5-15emu / g.It is prepared by fly ash pretreatment, mixed pulping, aging forming, high temperature calcination modification and magnetic separation purification in sequence.The raw material is cheap and easy to obtain, and the process is simple and controllable, with low energy consumption, which can be widely used in the adsorption and repair treatment of heavy metals, organic dyes and other pollutants in water body, and is convenient for engineering application.

Description

Technical Field

[0001] This invention relates to the field of environmental materials technology, specifically to a magnetically modified fly ash-based environmental mineral remediation material and its preparation method. Background Technology

[0002] Fly ash is a major industrial solid waste emitted by coal-fired power plants. Long-term stockpiling of large quantities of fly ash not only occupies land resources, but its leachate and dust can also cause secondary pollution to soil, water, and air. Fly ash itself possesses a porous structure and certain surface adsorption activity; processing it into environmental remediation materials is an important way to achieve high-value utilization of solid waste and treat waste with waste.

[0003] However, virgin fly ash has limited adsorption capacity, and its powdered state makes it difficult to quickly separate and recover from water bodies, easily causing secondary pollution and greatly limiting its large-scale application. Although existing magnetic modification technologies can endow fly ash with magnetic separation properties, they generally suffer from problems such as complex processes, expensive modifying reagents, and reliance on high-end functional materials, resulting in high preparation costs. At the same time, some modified materials have poor mechanical strength and underdeveloped pore structure, making it difficult to meet engineering requirements in terms of actual repair effects and recycling performance. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method for preparing a magnetically modified fly ash-based environmental mineral remediation material and its preparation. This material uses industrial solid waste fly ash as the core matrix, combined with conventional minerals and common chemical reagents, resulting in low raw material costs, balanced material adsorption and magnetic separation performance, a simple and controllable process, low energy consumption, and suitability for industrial mass production.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows: a magnetically modified fly ash-based environmental mineral remediation material, which is made from the following raw material components by weight: 60-80 parts fly ash, 15-30 parts magnetic iron source, 5-15 parts mineral binder, and 1-5 parts pore-forming agent; the remediation material uses fly ash as a matrix carrier and achieves magnetic modification through high-temperature reaction loading of magnetic iron source, with a material particle size of 0.15-1.0 mm and a saturation magnetization of 5-15 emu / g.

[0006] Furthermore, the magnetic iron source is one of ferrous sulfate heptahydrate and ferric chloride hexahydrate.

[0007] Furthermore, the mineral binder is one of sodium bentonite, kaolin, or attapulgite.

[0008] Furthermore, the pore-forming agent is one or both of soluble starch and carboxymethyl cellulose; the specific surface area of ​​the repair material is 30–80 m². 2 / g.

[0009] This invention also provides a method for preparing the above-mentioned magnetically modified fly ash-based environmental mineral remediation material, comprising the following steps: Step 1: Fly ash pretreatment: After sieving to remove impurities, the fly ash is dried in an oven to constant weight to obtain pretreated fly ash; Step 2: Mixing and slurry preparation: The magnetic iron source is dissolved in deionized water to prepare an iron salt solution, and the pretreated fly ash, mineral binder, and pore-forming agent are added sequentially, and the mixture is continuously stirred until the materials are evenly mixed to obtain a homogeneous mixed slurry; Step 3: Aging and molding: After the mixed slurry is aged at room temperature, it is extruded into strip-shaped blanks, naturally air-dried, crushed, and sieved; Step 4: High-temperature calcination modification: The sieved blanks are placed in a muffle furnace and calcined under a programmed temperature rise in an air atmosphere. After calcination, the blanks are naturally cooled with the furnace to obtain a crude material; Step 5: Magnetic separation and purification: The crude material is sent to a magnetic separation device for magnetic separation and the products with magnetic response are collected to obtain the magnetically modified fly ash-based environmental mineral remediation material.

[0010] Furthermore, in step one, the fly ash is passed through a 100-200 mesh standard sieve, the drying temperature is controlled at 105-110℃, and the drying time is 2-4 hours.

[0011] Furthermore, in step three, the aging time at room temperature is 12 to 24 hours; the diameter of the strip-shaped green body is 2 to 5 mm; after crushing, particles with a particle size of 0.15 to 1.0 mm are screened out for subsequent roasting.

[0012] Furthermore, in step four, the programmed heating rate is 5–10 °C / min, the calcination temperature is 400–600 °C, and the holding calcination time is 1–3 h.

[0013] Furthermore, in step five, the working magnetic field strength of the magnetic separator is 1000–3000 Gs, and the number of magnetic separation processes is 1–2.

[0014] The advantages of this invention compared to the prior art are: Realizing solid waste resource utilization: Using industrial solid waste fly ash as the main raw material, combined with common clay minerals and conventional chemical reagents, no high-end functional materials are required, which greatly reduces the preparation cost; at the same time, it disposes of industrial solid waste, reduces the environmental pressure caused by fly ash stockpiling, and is in line with the concept of green environmental protection.

[0015] The process is simple and controllable, and suitable for industrial production: The preparation process only includes five core steps: pretreatment, mixing and pulping, aging and molding, roasting and modification, and magnetic separation and purification. The process parameters are easy to control, the roasting temperature is moderate, the energy consumption is low, and no special equipment is required.

[0016] Balanced material performance: By regulating the pore structure through pore-forming agents, the specific surface area of ​​the material is increased and the adsorption sites are abundant, which can effectively remove pollutants such as heavy metals and cationic dyes in water. Magnetic components are generated in situ on the surface of fly ash at high temperature by a magnetic iron source, and the magnetic response is stable.

[0017] Wide range of applications: After high-temperature calcination, the mineral binder can significantly improve the mechanical strength and wear resistance of the material. The particle size is uniform and controllable, and it can be adapted to various water remediation scenarios such as in-situ addition, filling adsorption columns, and fluidized bed treatment. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the preparation method of magnetically modified fly ash-based environmental mineral remediation materials. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to three specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0020] Example 1 The magnetically modified fly ash-based environmental mineral remediation material of this embodiment, by weight, consists of the following raw material components: 70 parts fly ash, 22 parts ferrous sulfate heptahydrate, 10 parts sodium bentonite, and 3 parts soluble starch.

[0021] The preparation method specifically includes the following steps: Step 1: Fly ash pretreatment: Take dry fly ash from a coal-fired power plant, pass it through a 150-mesh standard sieve to remove coarse particles and impurities, place it in a 105℃ forced-air drying oven for 3 hours to constant weight, remove it and cool it to room temperature for later use, thus obtaining pretreated fly ash. Step 2: Mixing and slurry preparation: Weigh ferrous sulfate heptahydrate according to the formula, dissolve it in deionized water to prepare a 15% iron salt solution; add the pretreated fly ash, sodium bentonite and soluble starch in sequence, and stir continuously at 300 r / min for 40 minutes at room temperature until the materials are fully mixed, the slurry is uniform and free of lumps, thus obtaining a homogeneous mixed slurry. Step 3: Aging and Molding: Transfer the mixed slurry to a sealed container and allow it to age at room temperature for 18 hours. After aging, load it into a screw extruder and extrude it into strip-shaped billets with a diameter of 3 mm. Air dry the billets naturally until the moisture content is below 10%, then crush the billets and sieve to collect granular billets with a particle size of 0.15–1.0 mm. Step 4: High-Temperature Calcination and Modification: Spread the granular billets evenly in a corundum crucible and place it in a muffle furnace. Under an air atmosphere, the temperature is increased to 500°C at a rate of 8°C / min and calcined for 2 hours. After calcination, turn off the power and allow the furnace to cool naturally to room temperature to obtain the crude material. Step 5: Magnetic Separation and Purification: Send the crude material into a wet magnetic separator and treat it once under a working magnetic field strength of 2000 Gs. Discard the loose residue without magnetic response and collect the magnetic solid product to obtain the magnetically modified fly ash-based environmental mineral remediation material.

[0022] Performance testing: The saturation magnetization of the repair material prepared in this embodiment is 10.2 emu / g, and the specific surface area is 56 m². 2 / g; In an aqueous solution of cadmium ions with an initial concentration of 50 mg / L, with a material dosage of 2 g / L and an adsorption time of 2 h, the cadmium ion removal rate can reach 92.3%; The magnetic separation recovery rate under an external magnetic field can reach 98.5%.

[0023] Example 2 The magnetically modified fly ash-based environmental mineral remediation material of this embodiment, by weight, consists of the following raw material components: 80 parts fly ash, 15 parts ferric chloride hexahydrate, 5 parts kaolin, and 1 part carboxymethyl cellulose.

[0024] The preparation method specifically includes the following steps: Step 1: Fly ash pretreatment: Take dry fly ash from a coal-fired power plant, pass it through a 200-mesh standard sieve to remove coarse particles and impurities, place it in a 110℃ forced-air drying oven for 2 hours to constant weight, remove it and cool it to room temperature for later use, thus obtaining pretreated fly ash. Step 2: Mixing and slurry preparation: Weigh ferric chloride hexahydrate according to the formula, dissolve it in deionized water to prepare a 12% iron salt solution; add the pretreated fly ash, kaolin, and carboxymethyl cellulose in sequence, and stir continuously at 250 r / min for 30 minutes at room temperature until the materials are fully mixed, the slurry is uniform and free of lumps, thus obtaining a homogeneous mixed slurry. Step 3: Aging and Molding: Transfer the mixed slurry to a sealed container and allow it to age at room temperature for 12 hours. After aging, load it into a screw extruder and extrude it into strip-shaped billets with a diameter of 2 mm. Air dry the billets naturally until the moisture content is below 10%, then crush the billets and sieve to collect granular billets with a particle size of 0.15–1.0 mm. Step 4: High-Temperature Calcination and Modification: Spread the granular billets evenly in a corundum crucible and place it in a muffle furnace. Under an air atmosphere, the temperature is increased to 400°C at a rate of 5°C / min and calcined for 3 hours. After calcination, turn off the power and allow the furnace to cool naturally to room temperature to obtain the crude material. Step 5: Magnetic Separation and Purification: Feed the crude material into a wet magnetic separator and perform two consecutive magnetic separation treatments under a working magnetic field strength of 1000 Gs. Discard the loose residue without magnetic response and collect the magnetic solid phase product to obtain the magnetically modified fly ash-based environmental mineral remediation material.

[0025] Performance testing: The saturation magnetization of the repair material prepared in this embodiment is 5.8 emu / g, and the specific surface area is 35 m². 2 / g; In an aqueous solution of methylene blue with an initial concentration of 100 mg / L, with a material dosage of 3 g / L and an adsorption time of 2 h, the removal rate of methylene blue can reach 85.1%; The magnetic separation recovery rate under an external magnetic field can reach 95.2%.

[0026] Example 3 The magnetically modified fly ash-based environmental mineral remediation material of this embodiment, by weight, consists of the following raw material components: 60 parts fly ash, 30 parts ferric chloride hexahydrate, 15 parts attapulgite, and 5 parts soluble starch.

[0027] The preparation method specifically includes the following steps: Step 1: Fly ash pretreatment: Take dry fly ash from a coal-fired power plant, pass it through a 100-mesh standard sieve to remove coarse particles and impurities, place it in a 105℃ forced-air drying oven for 4 hours to constant weight, remove it and cool it to room temperature for later use, thus obtaining pretreated fly ash. Step 2: Mixing and slurry preparation: Weigh ferric chloride hexahydrate according to the ratio, dissolve it in deionized water to prepare an 18% iron salt solution; add the pretreated fly ash, attapulgite clay and soluble starch in sequence, and stir continuously at 350 r / min for 50 minutes at room temperature until the materials are fully mixed, the slurry is uniform and free of lumps, thus obtaining a homogeneous mixed slurry. Step 3: Aging and Molding: Transfer the mixed slurry to a sealed container and allow it to age at room temperature for 24 hours. After aging, load it into a screw extruder and extrude it into strip-shaped billets with a diameter of 5 mm. Air dry the billets naturally until the moisture content is below 10%, then crush the billets and sieve to collect granular billets with a particle size of 0.15–1.0 mm. Step 4: High-Temperature Calcination and Modification: Spread the granular billets evenly in a corundum crucible, place it in a muffle furnace, and calcine it to 600°C at a rate of 10°C / min under an air atmosphere. Hold the temperature for 1 hour. After calcination, turn off the power and allow the furnace to cool naturally to room temperature to obtain the crude material. Step 5: Magnetic Separation and Purification: Send the crude material into a wet magnetic separator and treat it once under a working magnetic field strength of 3000 Gs. Discard the loose residue with no magnetic response and collect the magnetic solid product to obtain the magnetically modified fly ash-based environmental mineral remediation material.

[0028] Performance testing: The saturation magnetization of the repair material prepared in this embodiment is 14.5 emu / g, and the specific surface area is 72 m². 2 / g; In an aqueous solution of lead ions with an initial concentration of 50 mg / L, with a material dosage of 2 g / L and an adsorption time of 2 h, the lead ion removal rate can reach 95.7%; The magnetic separation recovery rate under an external magnetic field can reach 99.1%.

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A magnetically modified fly ash-based environmental mineral remediation material, characterized in that, The material is made from the following raw materials in parts by weight: 60-80 parts fly ash, 15-30 parts magnetic iron source, 5-15 parts mineral binder, and 1-5 parts pore-forming agent. The repair material uses fly ash as the matrix carrier and achieves magnetic modification through high-temperature reaction loading of magnetic iron source. The material has a particle size of 0.15-1.0 mm and a saturation magnetization of 5-15 emu / g.

2. The magnetically modified fly ash-based environmental mineral remediation material according to claim 1, characterized in that, The magnetic iron source is either ferrous sulfate heptahydrate or ferric chloride hexahydrate.

3. The magnetically modified fly ash-based environmental mineral remediation material according to claim 1, characterized in that, The mineral binder is one of sodium bentonite, kaolin, or attapulgite.

4. The magnetically modified fly ash-based environmental mineral remediation material according to claim 1, characterized in that, The pore-forming agent is one or both of soluble starch and carboxymethyl cellulose; the specific surface area of ​​the repair material is 30-80 m². 2 / g.

5. A method for preparing a magnetically modified fly ash-based environmental mineral remediation material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Fly ash pretreatment: After sieving to remove impurities, fly ash is placed in an oven and dried to constant weight to obtain pretreated fly ash; Step 2: Mixing and pulping: Dissolve the magnetic iron source in deionized water to prepare an iron salt solution, then add pretreated fly ash, mineral binder and pore-forming agent in sequence, and continue stirring until the materials are mixed evenly to obtain a homogeneous mixed slurry; Step 3: Aging and molding: After the mixed slurry is left to stand at room temperature for aging, it is extruded into strip-shaped blanks, naturally air-dried, and then crushed and screened. Step 4: High-temperature roasting modification: The sieved billet is placed in a muffle furnace and roasted under a programmed temperature rise in an air atmosphere. After roasting, it is naturally cooled with the furnace to obtain the crude material. Step 5: Magnetic separation and purification: The crude material is fed into a magnetic separation device for magnetic separation and the product with magnetic response is collected to obtain the magnetically modified fly ash-based environmental mineral remediation material.

6. The preparation method according to claim 5, characterized in that, In step one, the fly ash is passed through a 100-200 mesh standard sieve, the drying temperature is controlled at 105-110℃, and the drying time is 2-4 hours.

7. The preparation method according to claim 5, characterized in that, In step three, the aging time at room temperature is 12 to 24 hours; the diameter of the strip-shaped green body is 2 to 5 mm; after crushing, particles with a particle size of 0.15 to 1.0 mm are screened out for subsequent roasting.

8. The preparation method according to claim 5, characterized in that, In step four, the programmed heating rate is 5–10℃ / min, the calcination temperature is 400–600℃, and the holding calcination time is 1–3h.

9. The preparation method according to claim 5, characterized in that, In step five, the working magnetic field strength of the magnetic separator is 1000–3000 Gs, and the number of magnetic separation processes is 1–2.

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