Solid waste-based core-shell particle as well as preparation method and application thereof

Abstract

The invention relates to a solid waste-based core-shell particle as well as a preparation method and application thereof. The solid-waste-based core-shell particle comprises an inner core and an outer shell wrapping the outer portion of the inner core, the inner core is porous and comprises solid waste particles and an inner core binder, the outer shell comprises solid waste particles and an outer shell binder, the average volume equivalent diameter of the solid waste particles is 0.5 mm or below, and the average volume equivalent diameter of the outer shell binder is 0.5 mm or below. And the average volume equivalent diameter of the solid waste-based core-shell particles is 5-15 mm. The solid waste-based core-shell particle has high mechanical property and high adsorption property, and can be used for soil improvement.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a solid waste-based core-shell particle, its preparation method and uses. Background Technology

[0002] Solid waste (also known as "solid waste") is increasingly generated and discharged in industrial production (such as slag and scrap metal), agricultural production (such as straw and livestock manure), urban construction (such as construction waste and demolition debris), daily life (such as kitchen waste and waste packaging), as well as commercial activities and medical processes. If left untreated, this solid waste will encroach on land, pollute soil and water sources, and release harmful gases, posing a threat to the ecological environment and public health. Therefore, the resource utilization of solid waste has always been an important issue for environmental protection and sustainable development.

[0003] Traditional methods of utilizing solid waste-based materials mainly include cementitious admixtures, concrete additives, and road base materials. However, there is still considerable room for improvement in the refinement and added value of these applications.

[0004] With population growth and agricultural development, the demand for soil resources is increasing, making soil improvement an increasingly important issue. Using solid waste for soil improvement is a win-win approach, enabling waste reuse while simultaneously enhancing the value of soil resources. Existing technologies have already made some efforts in this regard.

[0005] For example, Patent Document 1 discloses a method for promoting plant growth and soil improvement based on fly ash, which adds an appropriate amount of fly ash to the soil to adjust the pH of acidic soil, improve the soil physicochemical properties and soil structure (improving soil aeration and water retention), and at the same time provide nutrients for plants to promote plant growth.

[0006] Patent document 2 discloses a fly ash soil conditioner, which is prepared from the following raw materials in parts by weight: 50-70 parts modified fly ash, 15-25 parts humic acid, 30-40 parts organic matrix, 3-5 parts diatomaceous earth, 6-10 parts zeolite powder, 1.5-3.0 parts microbial agent, and 0.5-1.5 parts calcium carboxymethyl cellulose.

[0007] References

[0008] Patent Document 1: CN 120266623 A

[0009] Patent Document 2: CN 119955527 A Summary of the Invention

[0010] The problem the invention aims to solve

[0011] Patent Document 1 uses fly ash directly as a conditioner, while Patent Document 2 combines fly ash with organic matter and microorganisms. Both have significant room for improvement in terms of water retention and long-term effectiveness. Furthermore, both Patent Documents 1 and 2 involve directly mixing fly ash into the soil during application, requiring strict control of dosage and mixing methods to avoid additional dust pollution.

[0012] The purpose of this invention is to provide a solid waste-based core-shell particle with high mechanical and adsorption properties, which can be used for soil improvement, has excellent water retention, slow-release properties, and can avoid dust pollution.

[0013] Solution for solving the problem

[0014] To address the aforementioned problems, the inventors conducted long-term and in-depth research and proposed using solid waste as raw material to create a porous core, which is then encased in a relatively dense, hardened outer shell, thereby obtaining solid waste-based core-shell particles with high mechanical and adsorption properties. This led to the completion of this invention.

[0015] Specifically, the present invention solves the problems of the present invention through the following solutions.

[0016] [1] A solid waste-based core-shell particle, comprising a core and an outer shell covering the core, wherein the core is porous and comprises solid waste particles and a core binder, the outer shell comprises solid waste particles and an outer shell binder, wherein the average volume equivalent diameter of the solid waste particles is less than 0.5 mm, and the average volume equivalent diameter of the solid waste-based core-shell particle is 5 to 15 mm.

[0017] [2] According to the solid waste-based core-shell particles described in [1], wherein the solid waste particles are selected from one or more of boiler fly ash, furnace bottom ash, coal gasification slag, desulfurization gypsum, coal gangue, red mud, and metallurgical slag.

[0018] [3] According to the solid waste-based core-shell particles described in [1], wherein the core binder is selected from one or more of cement, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin.

[0019] [4] According to the solid waste-based core-shell particles described in [1], wherein the outer shell binder is selected from one or more of cement, sodium silicate water glass, potassium silicate water glass, calcium hydroxide, sodium hydroxide, potassium hydroxide, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin.

[0020] [5] According to the solid waste-based core-shell particles described in [1], wherein the core further comprises a core additive, the core additive being one or more selected from fertilizers, microorganisms, and pesticides.

[0021] [6] According to the solid waste-based core-shell particles described in [1], the outer shell further comprises an outer shell additive, which is selected from one or more of cement water-reducing agents, dispersants, accelerators, retarders, thickeners, and reinforcing fibers.

[0022] [7] According to the solid waste-based core-shell particles described in [1], wherein the porosity of the core is 20-45% and the average thickness of the shell is 0.2-1.2 mm.

[0023] [8] According to the solid waste-based core-shell particles described in [1], wherein the compressive strength of the solid waste-based core-shell particles is 0.1~2MPa.

[0024] [9] The method for preparing solid waste-based core-shell particles according to any one of [1] to [8] includes the following steps:

[0025] Preparation of core particles: Solid waste particles, core binder and optional core additives are mixed and granulated to obtain core particles;

[0026] Preparation of shell slurry: Solid waste particles, shell binder, water and optional shell additives are mixed to obtain shell slurry;

[0027] Coating: The outer shell slurry is coated onto the core particles using a rolling coating method, fluidized bed coating method, or impregnation coating method.

[0028]

[10] Use of solid waste-based core-shell particles according to any one of [1] to [8] for soil improvement.

[0029] The effects of the invention

[0030] The solid waste-based core-shell particles of this invention have high mechanical properties and high adsorption properties, and can be used for soil improvement.

[0031] The solid waste-based core-shell granules of this invention provide excellent water retention and slow-release properties when used for soil amendment. Furthermore, the method of mixing the granulated, large particles into the soil reduces the environmental risks associated with dust. In addition, the high mechanical properties of the solid waste-based core-shell granules of this invention prevent breakage during processing and also facilitate transportation. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of the solid waste-based core-shell particles prepared in Example 1. Detailed Implementation

[0033] The present invention will now be described in detail. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples.

[0034] <Terminology and Definitions>

[0035] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0036] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0037] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0038] In this specification, the terms "optionally" or "optionally" are used to indicate the use or non-use of certain substances, components, procedures, application conditions, etc.

[0039] All unit names used in this manual are international standard unit names, and unless otherwise stated, the "%" indicates weight or mass percentage.

[0040] In this specification, references to "preferred embodiments," "implementation methods," etc., mean that a specific element (e.g., feature, structure, property, and / or characteristic) related to that embodiment is included in at least one of the embodiments described herein, and may or may not be present in other embodiments. Furthermore, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0041] Solid waste-based core-shell granules

[0042] One object of the present invention is to provide a solid waste-based core-shell particle, comprising a core and a shell covering the core, wherein the core is porous and comprises solid waste particles and a core binder, and the shell comprises solid waste particles and a shell binder, wherein the average volume equivalent diameter of the solid waste particles is less than 0.5 mm, and the average volume equivalent diameter of the solid waste-based core-shell particle is 5 to 15 mm, preferably 5.2 to 10 mm, and also, for example, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, or 12 mm.

[0043] In some embodiments, the core porosity of the solid waste-based core-shell particles of the present invention is 20-45%, preferably 25-43%, and more preferably 30-42%.

[0044] In some embodiments, the average thickness of the outer shell in the solid waste-based core-shell particles of the present invention is 0.2 to 1.2 mm, preferably 0.3 to 0.8 mm.

[0045] In some embodiments, the compressive strength of the solid waste-based core-shell particles of the present invention is 0.1~2MPa, preferably 0.3~1.5MPa, and more preferably 0.6~1.0MPa.

[0046] The following describes in detail each component of the solid waste-based core-shell particles of the present invention.

[0047] solid waste

[0048] In some embodiments, the solid waste particles used in this invention are selected from one or more of boiler fly ash, furnace bottom ash, coal gasification slag, desulfurization gypsum, coal gangue, red mud, and metallurgical slag, with fly ash being preferred. These solid wastes are produced in large quantities and quantities, and their disposal is a major pain point in the industry. Furthermore, most of these solid wastes have experienced high-temperature environments and have weak adsorption properties; however, through granulation and bonding as in this invention, the gaps between the particles can serve as adsorption spaces.

[0049] In this invention, the average volumetric equivalent diameter of the solid waste particles is 0.5 mm or less, preferably 0.4 mm or less. By ensuring the average volumetric equivalent diameter of the solid waste particles is within this range, it is beneficial to subsequently bond the solid waste particles using a core binder, and bonding failure can be effectively avoided. From the perspective of reducing production costs, improving production efficiency, and facilitating dust-free operation, the particle size of the solid waste particles is preferably greater than 1 μm, more preferably greater than 10 μm, and most preferably greater than 20 μm.

[0050] In some embodiments, the solid waste-based core-shell particles of the present invention contain 70-99% by weight, preferably 80-98% by weight, more preferably 85-97% by weight, and for example 88% by weight, 90% by weight, 92% by weight, 94% by weight, 95% by weight, and 96% by weight.

[0051] In some implementations, based on the weight of the core, the content of solid waste particles is 90 to 99.999% by weight, preferably 92 to 99.995% by weight, more preferably 94 to 99.99% by weight, and also, for example, 95% by weight, 96% by weight, 97% by weight, 98% by weight, 99% by weight, etc.

[0052] In some embodiments, based on the weight of the shell, the content of solid waste particles is 60-98% by weight, preferably 70-97% by weight, more preferably 80-96% by weight, and also, for example, 85% by weight, 90% by weight, 92% by weight, 94% by weight, etc.

[0053] Core adhesive

[0054] In some implementations, the core binder is selected from one or more of cement, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin. Considering both cost and performance (cost-effectiveness), polyvinyl alcohol and starch are preferred.

[0055] In some implementations, based on the weight of the core, the content of the core binder is 0.001 to 5% by weight, preferably 0.005 to 4% by weight, more preferably 0.01 to 3% by weight.

[0056] shell adhesive

[0057] In some embodiments, the outer shell adhesive is selected from one or more of cement, sodium silicate water glass, potassium silicate water glass, calcium hydroxide, sodium hydroxide, potassium hydroxide, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin. Among these, cement, gypsum, sodium silicate, and sodium poly(meth)acrylate are preferred from the perspective of balancing cost and performance.

[0058] In some embodiments, the content of the shell adhesive is 1 to 30% by weight, preferably 2 to 25% by weight, and more preferably 3 to 20% by weight, based on the weight of the shell.

[0059] kernel additives

[0060] In some embodiments, the core also includes core additives, which are one or more selected from fertilizers, microorganisms, and pesticides. By introducing these additives into the core, the solid waste-based core-shell particles of the present invention can be endowed with other functions. For example, by introducing fertilizers into the core, the solid waste-based core-shell particles of the present invention possess the function of slow-release fertilizer, capable of providing fertility to the soil for a considerable period of time. As another example, by introducing pesticides into the core, the solid waste-based core-shell particles of the present invention possess the function of slow-release pesticide, capable of killing pests and other pests over a long period of time. Furthermore, by introducing microorganisms into the core, the solid waste-based core-shell particles of the present invention can regulate the soil microbial environment.

[0061] In some implementations, the content of the core additive is 0.01 to 10% by weight, preferably 0.1 to 8% by weight, more preferably 1 to 5% by weight, based on the weight of the core.

[0062] Shell additives

[0063] In some embodiments, the shell further comprises a shell additive, which is one or more selected from cement water-reducing agents, dispersants, accelerators, retarders, thickeners, and reinforcing fibers.

[0064] Examples of cement water-reducing agents include lignin sulfonate water-reducing agents, sulfonated coal tar-based water-reducing agents, sulfonated melamine-formaldehyde resin, and polycarboxylate water-reducing agents, with polycarboxylate water-reducing agents being preferred. When the outer shell adhesive contains cement, it is preferable that the outer shell additive contains a cement water-reducing agent.

[0065] The reinforcing fiber can be one or more selected from biomass fiber, polyethylene fiber, polypropylene fiber and glass fiber.

[0066] In some embodiments, the content of the shell additive is 0.01 to 20% by weight, preferably 0.1 to 15% by weight, based on the weight of the shell.

[0067] <Preparation Method>

[0068] One objective of this invention is to provide a method for preparing solid waste-based core-shell particles, characterized by comprising the following steps:

[0069] Preparation of core particles: Solid waste particles, core binder and optional core additives are mixed and granulated to obtain core particles;

[0070] Preparation of shell slurry: Solid waste particles, shell binder, water and optional shell additives are mixed to obtain shell slurry;

[0071] Coating: The outer shell slurry is coated onto the core particles using a rolling coating method, fluidized bed coating method, or impregnation coating method.

[0072] In some embodiments, the preparation method of the present invention further includes the following steps:

[0073] Curing: When the outer shell adhesive contains cement, it shall be cured in an environment with a relative humidity of ≥95% for 6~168h; when the outer shell adhesive contains NaOH, it shall be cured in a steam environment at 60~80℃ for 6~24h.

[0074] The following describes in detail each step of the preparation method of the present invention.

[0075] Preparation of kernel particles

[0076] In this invention, core particles are obtained by mixing and granulating solid waste particles, a core binder, and optional core additives.

[0077] In some embodiments, solid waste particles and a binder are mixed and granulated to obtain core particles, wherein the binder comprises a core binder, water, and optionally a core additive. Preferably, the amount of binder is 10% by weight or less of the solid waste particles, more preferably 5% by weight or less, and more preferably 3% by weight or less. From the perspective of sufficient bonding, the lower limit is generally 0.5% by weight or more, preferably 0.8% by weight or more.

[0078] In a specific implementation plan, solid waste particles are placed in a granulation device, a binder is added to the granulation device, and core particles are obtained by granulation through rolling, fluidization or extrusion.

[0079] Preferably, the adhesive liquid is atomized and added to the granulation equipment, more preferably sprayed into the granulation equipment.

[0080] In some embodiments, the invention further includes the preparation of the adhesive liquid. Specifically, the core adhesive, water, and optionally a core additive are mixed and optionally stirred to prepare the adhesive liquid. The content of the core adhesive is 0.5 to 5% by weight, based on the weight of the adhesive liquid.

[0081] In some implementations, solid waste particles, a core binder, and optional core additives are placed in a granulation apparatus, water is added to the granulation apparatus, and core particles are obtained by rolling, fluidizing, or extruding granulation.

[0082] Preferably, the water is atomized and added to the granulation equipment, more preferably it is sprayed into the granulation equipment.

[0083] Preparation of shell slurry

[0084] In this invention, a shell slurry is obtained by mixing solid waste particles, shell binder, water, and optional shell additives.

[0085] In some implementations, the shell slurry comprises, by weight: 60-85 parts solid waste particles, 5-20 parts shell binder, 10-25 parts water, and 0-2 parts shell additives.

[0086] In some implementations, the components are thoroughly mixed by applying stirring.

[0087] Cover

[0088] In this invention, the outer shell slurry is coated onto the core particles using a rolling coating method, a fluidized bed coating method, or an impregnation coating method.

[0089] In some implementations, fluidized bed coating machines, disc granulators, drum granulators, or impregnation machines are used for coating.

[0090] In some embodiments, a fluidized bed coating machine, a disc granulator, or a drum granulator is used for coating. In these embodiments, coating is preferably performed by:

[0091] The core particles are fully fluidized or uniformly tumbled in the equipment; the shell slurry is sprayed onto the surface of the tumbling core particles through an atomizing nozzle; and dry hot air at 40~80℃ is blown into the particle bed.

[0092] Dry hot air can be blown into the particle bed continuously or intermittently. The blown hot air helps to quickly evaporate the moisture in the outer shell slurry sprayed onto the surface of the core particles, and the solid components in the outer shell slurry are rapidly deposited on the surface of the core particles to form an outer shell.

[0093] In these implementation schemes, the average thickness and uniformity of the outer shell can be adjusted by regulating the spray rate of the outer shell slurry, atomization pressure, hot air temperature and volume, coating time, etc.

[0094] In some embodiments, an impregnation machine is used for coating. In these embodiments, coating is preferably performed in the following manner:

[0095] The core particles are immersed in the outer shell slurry for 5-30 seconds, and after draining off the excess slurry, an outer shell coating is formed. After drying, the solid waste-based core-shell particles of the present invention are obtained.

[0096] Other steps

[0097] In some embodiments, the method of the present invention optionally includes a pretreatment step of solid waste, said pretreatment step including one or more of washing, crushing, screening, and drying. Washing can remove impurities from the solid waste. Screening ensures that the equivalent average diameter of the particles is less than 0.5 mm and also removes impurities from the solid waste. Crushing can prevent larger solid waste particles from causing bonding failure in the subsequent bonding process. Drying can be carried out by placing the solid waste particles in an oven at a temperature of 90-120°C, preferably 100-10°C, for a drying time of 10-15 hours, preferably 11-13 hours. By drying to remove moisture from the solid waste particles, the ratio of solid waste particles to water in the bonding liquid can be more precisely controlled, making the bonding process more reliable.

[0098] The present invention also relates to solid waste-based core-shell particles obtained by the preparation method of the present invention.

[0099] <Application>

[0100] The present invention also relates to the use of solid waste-based core-shell particles for soil improvement, such as for soil moisturizers, pesticide slow-release, fertilizer slow-release, etc.

[0101] The present invention also relates to a soil improvement method comprising the step of incorporating the solid waste-based core-shell particles of the present invention into the soil.

[0102] Example

[0103] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by this invention.

[0104] Example 1

[0105] Core preparation: Take 1 kg of fly ash, place it in a disc granulator, and spray in 10 g of 2 wt% polyvinyl alcohol aqueous solution to make a core with an average volume equivalent diameter of 5 mm.

[0106] Preparation of shell slurry: Mix 1 kg of fly ash, 50 g of ordinary silicate cement (model PO 42.5), 150 g of water and 5 g of industrial polycarboxylate superplasticizer (water reduction rate 28%) and stir to make shell slurry.

[0107] Coating: The core is added to a fluidized bed, hot air at 50°C is introduced, and the outer shell slurry is atomized and sprayed at a pressure of 0.4 MPa to coat the outer shell to a thickness of 0.5 mm.

[0108] Curing: Curing at 20℃, normal pressure, and saturated humidity for 24 hours yields the finished granules.

[0109] Performance testing: The finished particles have a compressive strength of 0.8 MPa and a core porosity of 36%.

[0110] Example 2

[0111] Core preparation: The core was prepared in the same manner as in Example 1.

[0112] Preparation of shell slurry: Mix 1 kg of fly ash, 200 g of sodium silicate water glass (modulus 2.0, concentration 20 wt%) and 50 g of water and stir to prepare shell slurry.

[0113] Covering: The outer shell is covered in the same manner as in Example 1.

[0114] Curing: Curing is carried out in a 75℃ constant temperature curing chamber by introducing steam for 8 hours.

[0115] Performance testing: The functional particles have a compressive strength of 1.5 MPa and a core porosity of 36%.

[0116] Example 3

[0117] Core preparation: Take 1 kg of fly ash and 0.01 kg of starch, place them in a disc granulator, spray in 0.2 kg of water, and make a core with an average volume equivalent diameter of 5 mm.

[0118] Preparation of shell slurry: Fly ash (68.5 wt%), sodium polyacrylate (10 wt%), calcium chloride coagulant (1.5 wt%), and water (20 wt%) are mixed and stirred to prepare shell slurry.

[0119] Coating: Immerse the core in the shell slurry for 10 seconds to uniformly coat the core surface with a 1mm thick layer of shell slurry.

[0120] Curing: The core covered with the outer shell slurry is cured at 20°C for 1 hour.

[0121] Performance testing: The functional particles have a compressive strength of 0.5 MPa and a core porosity of 40%.

[0122] <Tests and Evaluations>

[0123] The compressive strength of the particles was tested using a particle compressive strength tester.

[0124] Porosity was measured using the gas adsorption method.

[0125] The compressive strength and porosity of the particles obtained in Examples 1-3 were determined according to the above method, as shown in Table 1.

[0126] Table 1

[0127]

[0128] As shown in Table 1, the core of the solid waste-based core-shell particles of the present invention has a high porosity, thus exhibiting excellent adsorption and slow-release properties. Furthermore, the solid waste-based core-shell particles of the present invention have high compressive strength, facilitating stacking and transportation, and effectively preventing particle breakage during use.

[0129] Industrial availability

[0130] The solid waste-based core-shell particles of this invention can be widely used for soil improvement, such as for soil moisture retention, pesticide slow release, and fertilizer slow release.

Claims

1. A solid waste-based core-shell granule, characterized in that: It includes a core and a shell covering the core. The core is porous and includes solid waste particles and a core binder. The shell includes solid waste particles and a shell binder. The average volume equivalent diameter of the solid waste particles is less than 0.5 mm, and the average volume equivalent diameter of the solid waste-based core-shell particles is 5 to 15 mm.

2. The solid waste-based core-shell particles according to claim 1, characterized in that: The solid waste particles are selected from one or more of the following: boiler fly ash, furnace bottom ash, coal gasification slag, desulfurization gypsum, coal gangue, red mud, and metallurgical slag.

3. The solid waste-based core-shell particles according to claim 1, characterized in that: The core binder is selected from one or more of cement, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin.

4. The solid waste-based core-shell particles according to claim 1, characterized in that: The outer shell adhesive is selected from one or more of the following: cement, sodium silicate water glass, potassium silicate water glass, calcium hydroxide, sodium hydroxide, potassium hydroxide, gypsum, polyvinyl alcohol, sodium poly(meth)acrylate, sodium silicate, carboxymethyl cellulose, starch, poly(meth)acrylate, and epoxy resin.

5. The solid waste-based core-shell particles according to claim 1, characterized in that: The core also includes a core additive, which is one or more selected from fertilizers, microorganisms, and pesticides.

6. The solid waste-based core-shell particles according to claim 1, characterized in that: The outer shell also includes an outer shell additive, which is one or more selected from cement water-reducing agents, dispersants, accelerators, retarders, thickeners, and reinforcing fibers.

7. The solid waste-based core-shell particles according to claim 1, characterized in that: The core has a porosity of 20-45%, and the outer shell has an average thickness of 0.2-1.2 mm.

8. The solid waste-based core-shell particles according to claim 1, characterized in that: The compressive strength of the solid waste-based core-shell particles is 0.1~2MPa.

9. The method for preparing solid waste-based core-shell particles according to any one of claims 1 to 8, characterized in that, Includes the following steps: Preparation of core particles: Solid waste particles, core binder and optional core additives are mixed and granulated to obtain core particles; Preparation of shell slurry: Solid waste particles, shell binder, water and optional shell additives are mixed to obtain shell slurry; Coating: The outer shell slurry is coated onto the core particles using a rolling coating method, fluidized bed coating method, or impregnation coating method.

10. Use of solid waste-based core-shell particles according to any one of claims 1 to 8 for soil improvement.

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