Light high-strength ceramsite based on fly ash and preparation method thereof

Abstract

The invention provides light-weight high-strength ceramsite based on fly ash and a preparation method of the light-weight high-strength ceramsite, and belongs to the technical field of ceramsite. The fly ash-based lightweight high-strength ceramsite is prepared from the following raw materials in parts by weight: 10 to 20 parts of fly ash, 5 to 10 parts of surface treatment sludge, 21 to 32 parts of coal gangue or polluted soil or a mixture of the coal gangue and the polluted soil in any proportion, 15 to 25 parts of construction waste, 10 to 17 parts of waste glass, 7 to 12 parts of oil-containing diatomite pyrolysis residues and 3 to 6 parts of waste emulsion. According to the method, the fly ash and the solid waste or the hazardous waste are reasonably utilized for co-processing, the ceramic forming performance of the fly ash is improved, and the high-quality and high-strength ceramsite is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramsite, and particularly relates to a lightweight and high-strength ceramsite based on fly ash and a preparation method thereof. Background Art

[0002] With the acceleration of the urbanization process and the improvement of people's living standards, the amount of municipal solid waste generated each year is increasing. As an effective waste treatment method, waste incineration can significantly reduce the volume of waste and recover heat energy, but at the same time, it will also generate a certain amount of fly ash. Fly ash contains a large amount of harmful substances such as heavy metals and dioxins. If not properly treated, it will cause serious pollution to the environment. Traditional fly ash treatment methods such as landfilling not only occupy a large amount of land resources but also pose a risk of secondary pollution. Therefore, it is particularly important to seek a method that can not only achieve harmless treatment of fly ash but also realize its resource utilization.

[0003] Ceramsite is a lightweight aggregate with a porous structure, having many excellent properties such as light weight, high strength, heat insulation, fire resistance, and strong seismic performance. In the construction field, ceramsite can be widely used in concrete preparation, lightweight partition boards, roof insulation and leveling, landscaping, etc. The concrete made with ceramsite as the aggregate has a lower density than ordinary concrete, but its compressive strength can be maintained at a relatively high level, which can effectively reduce the self-weight of buildings and lower the cost of foundation engineering. At the same time, the heat insulation performance of ceramsite can improve the energy efficiency of buildings, and its fire resistance can enhance the fire safety of buildings. In addition, ceramsite also has certain sound absorption performance and can be used in places with high acoustic design requirements.

[0004] In recent years, the preparation of ceramsite from fly ash has become a research hotspot in the field of solid waste resource utilization. Researchers have successfully prepared ceramsite products with certain properties by mixing fly ash with other raw materials such as clay, sludge, fly ash, etc., through processes such as pretreatment, granulation, and sintering. These studies have, to a certain extent, realized the harmlessness and resource utilization of fly ash, providing new ideas for fly ash treatment. However, the current technology for preparing ceramsite from fly ash is still in the research and pilot test stage. Although it has good application prospects, it still faces some problems that need to be solved urgently in practical applications. In order to reduce the content of harmful substances in fly ash and improve its ceramization performance, fly ash usually needs to be pretreated, such as dechlorination, impurity removal, stabilization, etc. However, these pretreatment methods are often cumbersome and costly. For example, common chemical treatment methods such as acid washing and alkali washing will produce a large amount of wastewater, which is difficult to treat and prone to secondary pollution; while physical methods such as water washing are relatively simple, but their effects on removing some insoluble impurities and heavy metals are limited. Therefore, if the cumbersome steps of fly ash pretreatment can be reduced through co-disposal, the utilization efficiency of fly ash will be greatly improved.

[0005] In addition, although fly ash ceramsite has the characteristic of light weight, there is still a certain gap in strength compared with traditional ceramsite, especially in the application of high-strength building structural materials. Therefore, there is still great potential for optimization and expansion in the co-disposal of fly ash to prepare high-performance ceramsite.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a light-weight and high-strength ceramsite in view of the deficiencies of the prior art, and to improve the ceramization performance of fly ash by co-disposing fly ash.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: a fly ash-based light-weight and high-strength ceramsite, comprising the following raw materials in parts by weight: 10-20 parts of fly ash, 5-10 parts of surface-treated sludge, 21-32 parts of coal gangue or contaminated soil or a mixture of the two in any proportion, 15-25 parts of construction waste, 10-17 parts of waste glass, 7-12 parts of pyrolysis residue of oil-containing diatomite, and 3-6 parts of waste emulsion.

[0009] Optionally, the construction waste contains the following chemical components in mass percentage: 30-50% of SiO2, 5-15% of CaO, and 10-20% of Al2O3.

[0010] Optionally, the waste glass contains the following chemical components in mass percentage: ≥70% of SiO2, 10-15% of Na2O, and 5-10% of CaO.

[0011] Optionally, the mass percentage of SiO2 in the pyrolysis residue of oil-containing diatomite ≥60%.

[0012] Optionally, the particle size of the fly ash, coal gangue or contaminated soil or a mixture of the two in any proportion, construction waste and pyrolysis residue of oil-containing diatomite ≤100 mesh.

[0013] Optionally, for the fly ash-based light-weight and high-strength ceramsite, its active components and their mass percentages are composed of: 50-60% of SiO2, 15-23% of Al2O3, 3-5% of Fe2O3, 10-13% of CaO, 1-3% of MgO, 3-8% of Na2O, and the CaO / SiO2 ratio is controlled at 0.2-0.3. SiO2: is the main framework component of ceramsite. Through high-temperature sintering, SiO2 reacts with Al2O3 to form a stable silicate structure, and reacts with CaO (CaO / SiO2 = 0.2-0.3) to generate wollastonite (CaSiO3), reducing the melting viscosity, promoting the uniform distribution of the liquid phase, and synergistically improving the strength and stability of ceramsite.

[0014] SiO2: is the main framework component of ceramsite. Through high-temperature sintering, SiO2 reacts with Al2O3 to form a stable silicate structure, and reacts with CaO (CaO / SiO2 = 0.2-0.3) to generate wollastonite (CaSiO3), reducing the melting viscosity, promoting the uniform distribution of the liquid phase, and synergistically improving the strength and stability of ceramsite.

[0015] Al2O3: Enhance the hardness of the ceramsite, and at the same time form a glass phase with SiO2 during the sintering process to improve the strength of the ceramsite.

[0016] CaO + MgO: CaO can react with components such as SiO2 and Al2O3 to form stable silicates and aluminates, improving the strength of the ceramsite. At the same time, CaO may react with the Cl element in the fly ash to reduce the leaching of the Cl element. MgO inhibits the crystallization of the glass phase at high temperatures, improves the creep resistance, and reduces the high-temperature deformation rate.

[0017] Fe2O3: An oxidation-reduction reaction occurs during the high-temperature sintering process, releasing gas, assisting in pore formation, forming a porous structure, and reducing the density of the ceramsite.

[0018] Na2O: Reduce the sintering temperature, promote the melting and bonding between particles, improve the strength of the ceramsite, and at the same time reduce energy consumption.

[0019] The present invention also provides a preparation method of lightweight and high-strength ceramsite based on fly ash, comprising the following steps: S1: Sufficiently mix fly ash, surface-treated sludge, coal gangue or contaminated soil or a mixture of the two in any proportion, construction waste, pyrolysis residue of oil-containing diatomite, and waste emulsion in a stirring device to obtain a mixture. S2: Transport the mixture to a homogenizer for pressure homogenization to obtain a homogenized material. S3: Transport the homogenized material to a spray dryer for spray drying to obtain dry granules. S4: Transport the dry granules to a high-temperature sintering furnace, preheat the high-temperature sintering furnace to 400 - 500 °C, hold for 30 - 50 min, then raise the temperature to 1050 - 1150 °C, hold for 20 - 40 min, and cool to obtain the product.

[0020] Optionally, the process parameters of the pressure homogenization include: the homogenization pressure is 30 - 35 MPa, the homogenization temperature is 40 - 50 °C, and the homogenization time is 15 - 20 min.

[0021] Optionally, the process parameters of the spray drying include: the inlet air temperature is 200 - 230 °C, the outlet air temperature is 70 - 80 °C, and the spray pressure is 0.8 - 1.0 MPa.

[0022] The components and functions of each raw material in the present invention are as follows: Fly ash: The main components are oxides such as SiO2, Al2O3, CaO, and Fe2O3, among which the content of SiO2 is the highest, followed by Al2O3. Fly ash contains heavy metals such as Pb and Cd, and their contents are affected by the composition of the garbage and the incineration process. Fly ash provides a silicate-aluminate skeleton and forms a glass phase at high temperatures, and heavy metals can be co-cured at high temperatures.

[0023] Surface treatment sludge: Belongs to HW17 surface treatment waste, specifically sourced from: waste corrosion liquid, waste washing liquid, waste bath liquid, bath slag and wastewater treatment sludge generated from acid (alkali) washing, degreasing, rust removal (excluding sandblasting rust removal), washing, phosphating, brightening, and chemical polishing processes on metal or plastic surfaces (not including: wastewater treatment sludge from acid (alkali) washing, roughening, sulfuric acid anodizing, and phosphoric acid chemical polishing of aluminum materials (plates), wastewater treatment sludge from chemical corrosion of aluminum electrodes for aluminum electrolytic capacitors and non-boric acid-based forming liquefaction, wastewater treatment sludge from alkali washing (potting) of aluminum extrusion processing molds, and wastewater treatment sludge from carbon steel pickling and rust removal, including: phosphating sludge, pickling sludge, fluorine-containing sludge, etc., which contain a certain amount of heavy metal elements and organic substances, etc. Some organic substances can be decomposed by high temperature to form pores and reduce density, reasonably added to optimize the porosity, and at the same time, heavy metals can be fixed in the high-temperature glass phase or mineral phase to reduce the leaching risk.

[0024] Coal gangue: Mainly contains SiO2, Al2O3, Fe2O3, and a small amount of C. Among them, SiO2 is 20 - 50%, Al2O3 is 15 - 30%, Fe2O3 is 1 - 7%, and CaO is 0.5 - 5%. It mainly provides silicon-aluminum sources, forms a framework structure at high temperatures, and improves the strength of ceramsite; a small amount of carbon can adjust foaming and reduce density. Coal gangue and construction waste provide framework support, prevent ceramsite from collapsing due to excessive micropores, and ensure strength while maintaining a low density.

[0025] Contaminated soil: Industrial-source contaminated soil is selected. In addition to containing mineral components such as silicon, aluminum, and iron, it also contains a certain amount of heavy metals and organic substances. As a raw material for preparing ceramsite, contaminated soil can provide silicon-aluminum sources. When used in combination with coal gangue, the ratio of the two can be adjusted according to needs. Preferably, the mass ratio of coal gangue to contaminated soil is (1 - 9):1 to meet the requirements of the framework structure of ceramsite; at the same time, heavy metals in contaminated soil can be solidified at high temperatures to reduce dissolution, and organic substances can be further treated after decomposition. At the same time, a part of the gas also participates in the pore formation of ceramsite to reduce the density of ceramsite.

[0026] Construction waste: Mainly contains CaO, SiO2, and Al2O3. Among them, by mass, SiO2 is 30 - 50%, CaO is 5 - 15%, and Al2O3 is 10 - 20%. It provides calcium sources and silicon-aluminum sources for making ceramsite, enhances the framework structure of coal gangue and / or contaminated soil, promotes the formation of high-temperature liquid phase, and enhances sintering densification.

[0027] Waste glass: Mainly contains SiO2, Na2O, and K2O. Among them, SiO2 ≥ 70%, Na2O is 10 - 15%, and CaO is 5 - 10%. As a low-temperature melting agent, it reduces the sintering temperature (1000 - 1150 °C) and reduces energy consumption; at the same time, it promotes the formation of glass phase, wraps heavy metals, and enhances strength.

[0028] Oil-containing diatomite pyrolysis residue: It is the pyrolysis product of oil-containing diatomite. Oil-containing diatomite is produced in the production process of lubricating oil additives and belongs to hazardous waste with high environmental risks. Currently, the treatment of oil-containing diatomite adopts the process of anaerobic high-temperature pyrolysis distillation. The solid phase produced is diatomite, inorganic substances and residual carbon. Traditional treatment is to separate deoiled diatomite, inorganic substances and residual carbon. The present invention directly utilizes this solid phase part, which mainly contains SiO2≥60%, and also contains hydrocarbon compounds and a small amount of residual carbon. It has a porous structure. The porous structure of the residual organic matter in it provides a pore-forming template, and the residual organic matter foams at high temperature for the second time, further reducing the density of the ceramsite.

[0029] Waste emulsion: It belongs to HW09 oil / water, hydrocarbon / water mixture or emulsion in the National Hazardous Waste List (2025 Edition), including three small codes 900-005-09, 900-006-09, 900-007-09. The industries that produce waste emulsion mainly include the machining industry, the electronics industry, the surface treatment industry, etc. The main pollution characteristics are high organic matter. Waste emulsion mainly contains water, oils, surfactants, etc., which can improve the formability of raw materials. The oils crack at high temperature to generate gases, foam to form pores, optimize the pore distribution and reduce the density.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the above technical solutions, the present invention provides a lightweight and high-strength ceramsite. By co-disposing fly ash, the ceramization performance of fly ash is improved. Fly ash is combined with a specific amount of surface treatment sludge, coal gangue or contaminated soil or any proportion mixture of the two, construction waste, oil-containing diatomite pyrolysis residue and waste emulsion. Through the coordination of components and processes, the strength of the ceramsite is further improved.

[0031] In the present invention, the oxides in fly ash and surface treatment sludge react with the silicon-aluminum components in coal gangue or contaminated soil or any proportion mixture of the two, and construction waste to form a solid glassy substance, improving the strength of the ceramsite. At the same time, CaO in fly ash and heavy metal compounds in surface treatment sludge undergo chemical reactions during sintering to form a stable glassy substance, reducing the risk of heavy metal leaching. Coal gangue or contaminated soil or any proportion mixture of the two and construction waste are both rich in SiO2 and Al2O3, which synergistically enhance the ceramsite skeleton, prevent the ceramsite from collapsing due to excessive micropores, ensure the strength while maintaining a low density, improve the durability and reduce the leaching of harmful substances. The fluxing effect of waste glass is combined with the micropore formation effect of oil-containing diatomite pyrolysis residue to reduce the sintering temperature, reduce energy consumption, and at the same time form a large number of micropores inside the ceramsite, reducing the density and improving the heat insulation performance. Both waste emulsion and oil-containing diatomite pyrolysis residue contain hydrocarbon compounds, which burn and decompose during the sintering process to form a large number of micropores, further reducing the density of the ceramsite.

[0032] Based on the characteristics of raw materials, the present invention optimizes the conventional ceramsite preparation process. By combining premixing, homogenization, spray drying and high-temperature sintering, the raw materials are granulated on the basis of sufficient mixing and homogenization, reducing compositional segregation and enabling the components in the granulated material to fully react during high-temperature sintering. The granulation process uses spray drying, and the process parameters are strictly controlled to controllably convert the homogenized material into granulated material. During the drying process, water evaporation forms initial pores, laying the foundation for subsequent sintering pore formation. The granulated material after spray drying enters a high-temperature sintering furnace for sintering to produce ceramics. Two-stage temperature control is adopted in the high-temperature sintering furnace. First, it is maintained at 400 - 500 °C for 30 - 50 min to decompose the organic matter in the granulated material and avoid rapid decomposition after heating, which may lead to structural collapse. Then, the temperature is raised to 1050 - 1150 °C and maintained for 20 - 40 min, and the components react to form a dense surface layer and an internal porous structure.

[0033] Through the coordinated treatment of raw materials and process, the bulk density of the obtained ceramsite of the present invention is ≤ 800 kg / m 3 , especially including density grades of 800, 700, 600, 500 and 400, with a 1-hour water absorption rate between 6% - 10%, a cylinder compressive strength ≥ 6.0 MPa, a boiling mass loss ≤ 3.0%, a loss on ignition ≤ 4.2%, and the contents of sulfides and sulfates (calculated as SO3), organic matter, chlorides (calculated as chloride ion content), and radioactivity all meeting the requirements of GB / T 17431.1. Detailed implementation manners

[0034] To better understand the present invention, the content of the present invention will be further clearly elaborated below in combination with embodiments. However, the protected content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0035] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0036] Unless otherwise specified, all raw materials are sourced from commercially available products and, unless otherwise specified, do not contain other unspecified components except for inevitable impurities.

[0037] In the following cases, the chemical compositions of the raw materials are as follows: The construction waste contains the following chemical components by mass percentage: SiO2 30 - 50%, CaO 5 - 15%, Al2O3 10 - 20%.

[0038] Waste glass contains the following chemical components in percentage by mass: SiO2 ≥ 70%, Na2O 10-15%, CaO 5-10%.

[0039] The mass percentage of SiO2 in the pyrolysis residue of oil-containing diatomite is ≥60%.

[0040] The particle size of fly ash, coal gangue or contaminated soil or any mixture of the two in any proportion, construction waste, oil-containing diatomaceous earth pyrolysis residue and waste emulsion is 100 mesh.

[0041] In the following embodiment, a fly ash-based lightweight high-strength ceramsite is made from the following raw materials in parts by weight: 10-20 parts of fly ash, 5-10 parts of surface-treated sludge, 21-32 parts of coal gangue or contaminated soil or a mixture of the two in any proportion, 15-25 parts of construction waste, 10-17 parts of waste glass, 7-12 parts of oil-containing diatomaceous earth pyrolysis residue, and 3-6 parts of waste emulsion.

[0042] Example 1: A fly ash-based lightweight high-strength ceramsite is made from the following raw materials in parts by weight: 10 parts of fly ash, 10 parts of surface-treated sludge, 30 parts of coal gangue, 20 parts of construction waste, 15 parts of waste glass, 10 parts of oil-containing diatomaceous earth pyrolysis residue, and 5 parts of waste emulsion.

[0043] A fly ash-based lightweight high-strength ceramsite, whose effective components and their mass percentages are as follows: SiO2 50.0%, Al2O3 21.3%, Fe2O3 3.5%, CaO 10.0%, MgO 2.3%, Na2O 8.0%, and the CaO / SiO2 ratio is controlled at 0.20.

[0044] A method for preparing lightweight and high-strength ceramsite based on fly ash comprises the following steps: S1: fully mixing fly ash, surface treatment sludge, coal gangue, construction waste, oil-containing diatomaceous earth pyrolysis residue and waste emulsion in a stirring device to obtain a mixture; S2: conveying the mixed material to a homogenizer for pressurized homogenization to obtain a homogenous material; S3: transporting the homogenized material to a spray dryer for spray drying to obtain dry granules; S4: The dry pellets are transported to a high-temperature sintering furnace, which is preheated to 450°C, maintained for 42 minutes, then heated to 1100°C, maintained for 30 minutes, and cooled to obtain the product.

[0045] The process parameters of pressurized homogenization include: homogenization pressure of 32 MPa, homogenization temperature of 43°C, and homogenization time of 17 min.

[0046] The process parameters of spray drying include: inlet air temperature of 210°C, outlet air temperature of 75°C, and spray pressure of 0.9MPa.

[0047] Example 2: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials by weight: 18 parts of fly ash, 9 parts of surface-treated sludge, 28 parts of coal gangue, 19 parts of construction waste, 13 parts of waste glass, 9 parts of pyrolysis residue of oil-containing diatomite, and 4 parts of waste emulsion.

[0048] A lightweight and high-strength ceramsite based on fly ash, its active components and their mass percentage composition are: SiO2 60.0%, Al2O3 15.0%, Fe2O3 3.2%, CaO 12.3%, MgO 1.1%, Na2O 3.1%, and the CaO / SiO2 ratio is controlled at 0.21.

[0049] A preparation method of a lightweight and high-strength ceramsite based on fly ash includes the following steps: S1: Sufficiently mix fly ash, surface-treated sludge, coal gangue, construction waste, pyrolysis residue of oil-containing diatomite, and waste emulsion in a stirring device to obtain a mixture. S2: Transport the mixture to a homogenizer for pressure homogenization to obtain a homogenized material. S3: Transport the homogenized material to a spray dryer for spray drying to obtain dry granules. S4: Transport the dry granules to a high-temperature sintering furnace, preheat the high-temperature sintering furnace to 420 °C, hold for 45 min, then raise the temperature to 1120 °C, hold for 27 min, and cool to obtain the product.

[0050] The process parameters of pressure homogenization include: homogenization pressure is 35 MPa, homogenization temperature is 40 °C, and homogenization time is 15 min.

[0051] The process parameters of spray drying include: inlet air temperature 220 °C, outlet air temperature 78 °C, and spray pressure is 0.8 MPa.

[0052] Example 3: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials by weight: 20 parts of fly ash, 8 parts of surface-treated sludge, 22 parts of coal gangue, 23 parts of construction waste, 14 parts of waste glass, 82 parts of pyrolysis residue of oil-containing diatomite, and 5 parts of waste emulsion.

[0053] A lightweight and high-strength ceramsite based on fly ash, its active components and their mass percentage composition are: SiO2 52.4%, Al2O3 20.8%, Fe2O3 3.0%, CaO 10.5%, MgO 2.5%, Na2O 4.5%, and the CaO / SiO2 ratio is controlled at 0.20.

[0054] A preparation method of a lightweight and high-strength ceramsite based on fly ash is carried out with reference to Example 1.

[0055] Example 4: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials in parts by weight: 17 parts of fly ash, 8 parts of surface treatment sludge, 27 parts of contaminated soil, 15 parts of construction waste, 16 parts of waste glass, 11 parts of oil-containing diatomaceous earth pyrolysis residue, and 6 parts of waste emulsion.

[0056] A fly ash-based lightweight high-strength ceramsite, whose effective components and their mass percentages are as follows: SiO2 53.0%, Al2O3 22.7%, Fe2O3 3.0%, CaO 11.2%, MgO 2.0%, Na2O 3.0%, and the CaO / SiO2 ratio is controlled at 0.21.

[0057] A method for preparing lightweight and high-strength ceramsite based on fly ash comprises the following steps: S1: fully mixing fly ash, surface treatment sludge, contaminated soil, construction waste, oil-containing diatomaceous earth pyrolysis residue and waste emulsion in a stirring device to obtain a mixture; S2: conveying the mixed material to a homogenizer for pressurized homogenization to obtain a homogenous material; S3: transporting the homogenized material to a spray dryer for spray drying to obtain dry granules; S4: The dry pellets are transported to a high-temperature sintering furnace, and the high-temperature sintering furnace is preheated to 500°C, maintained for 30 minutes, and then heated to 1150°C, maintained for 20 minutes, and cooled to obtain the product.

[0058] The process parameters of pressurized homogenization include: homogenization pressure of 35 MPa, homogenization temperature of 40°C, and homogenization time of 15 min.

[0059] The process parameters of spray drying include: inlet air temperature of 200°C, outlet air temperature of 70°C, and spray pressure of 0.8MPa.

[0060] Example 5: A fly ash-based lightweight and high-strength expanded clay, made from the following raw materials in parts by weight: 19 parts of fly ash, 10 parts of surface treatment sludge, 21 parts of contaminated soil, 25 parts of construction waste, 10 parts of waste glass, 12 parts of oil-containing diatomaceous earth pyrolysis residue, and 3 parts of waste emulsion.

[0061] A fly ash-based lightweight high-strength ceramsite, whose effective components and their mass percentages are as follows: SiO2 54.3%, Al2O3 15.5%, Fe2O3 4.8%, CaO 12.5%, MgO 2.3%, Na2O 4.0%, and the CaO / SiO2 ratio is controlled at 0.23.

[0062] A method for preparing lightweight and high-strength ceramsite based on fly ash is carried out with reference to Example 4.

[0063] Example 6: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials in parts by weight: 17 parts of fly ash, 9 parts of surface treated sludge, 24 parts of a mixture of coal gangue and contaminated soil, 21 parts of construction waste, 17 parts of waste glass, 7 parts of oil-containing diatomaceous earth pyrolysis residue, and 5 parts of waste emulsion, wherein the mass ratio of the mixture of coal gangue and contaminated soil is 5:1.

[0064] A fly ash-based lightweight high-strength ceramsite, whose effective components and their mass percentages are as follows: SiO2 58.7%, Al2O3 15.0%, Fe2O3 3.2%, CaO 12.9%, MgO 1.0%, Na2O 3.6%, and the CaO / SiO2 ratio is controlled at 0.22.

[0065] A method for preparing lightweight and high-strength ceramsite based on fly ash comprises the following steps: S1: fully mixing fly ash, surface treatment sludge, coal gangue and contaminated soil mixture, construction waste, oil-containing diatomaceous earth pyrolysis residue and waste emulsion in a stirring device to obtain a mixture; S2: conveying the mixed material to a homogenizer for pressurized homogenization to obtain a homogenous material; S3: transporting the homogenized material to a spray dryer for spray drying to obtain dry granules; S4: The dry pellets are transported to a high-temperature sintering furnace, which is preheated to 400°C, maintained for 50 minutes, then heated to 1050°C, maintained for 40 minutes, and cooled to obtain the product.

[0066] The process parameters of pressurized homogenization include: homogenization pressure of 30 MPa, homogenization temperature of 50°C, and homogenization time of 20 min.

[0067] The process parameters of spray drying include: inlet air temperature of 230°C, outlet air temperature of 80°C, and spray pressure of 1.0MPa.

[0068] Example 7: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials in parts by weight: 15 parts of fly ash, 7 parts of surface treated sludge, 32 parts of a mixture of coal gangue and contaminated soil, 17 parts of construction waste, 12 parts of waste glass, 12 parts of oil-containing diatomaceous earth pyrolysis residue, and 5 parts of waste emulsion, wherein the mass ratio of the mixture of coal gangue and contaminated soil is 1:1.

[0069] A lightweight and high-strength ceramsite based on fly ash, whose effective components and their mass percentages are as follows: SiO2 54.1%, Al2O3 16.5%, Fe2O3 3.5%, CaO 13.0%, MgO 1.5%, Na2O 4.5%, and the CaO / SiO2 ratio is controlled at 0.24.

[0070] A method for preparing lightweight and high-strength ceramsite based on fly ash is carried out with reference to Example 6.

[0071] Example 8: A lightweight and high-strength ceramsite based on fly ash is made from the following raw materials in parts by weight: 20 parts of fly ash, 5 parts of surface-treated sludge, 29 parts of a mixture of coal gangue and contaminated soil, 18 parts of construction waste, 12 parts of waste glass, 11 parts of pyrolysis residue of oil-containing diatomite, and 5 parts of waste emulsion, wherein: the mass ratio of the coal gangue to the contaminated soil mixture is 9:1.

[0072] A lightweight and high-strength ceramsite based on fly ash, its active ingredients and their mass percentage compositions are: SiO2 50.8%, Al2O3 17.6%, Fe2O3 4.2%, CaO 12.3%, MgO 1.2%, Na2O 6.7%, and the CaO / SiO2 ratio is controlled at 0.24.

[0073] The preparation method of a lightweight and high-strength ceramsite based on fly ash is carried out with reference to Example 6.

[0074] Comparative Example 1: A lightweight and high-strength ceramsite based on fly ash, which is different from Example 1 in that fly ash is used to replace coal gangue. The preparation method of this comparative example refers to Example 1.

[0075] Comparative Example 2: A ceramsite prepared based on fly ash, which is different from Example 1 in that the fly ash is adjusted to 25 parts by weight, and the other raw materials and parts by weight remain unchanged. The preparation method of this comparative example refers to Example 1.

[0076] Comparative Example 3: A ceramsite prepared based on fly ash, which is different from Example 1 in that the waste glass is adjusted to 20 parts by weight and the pyrolysis residue of oil-containing diatomite is adjusted to 5 parts by weight, and the other raw materials and parts by weight remain unchanged. The preparation method of this comparative example refers to Example 1.

[0077] Comparative Example 4: A ceramsite prepared based on fly ash, which is different from Example 1 in that the waste glass is adjusted to 5 parts by weight and the pyrolysis residue of oil-containing diatomite is adjusted to 20 parts by weight, and the other raw materials and parts by weight remain unchanged. The preparation method of this comparative example refers to Example 1.

[0078] Comparative Example 5: A ceramsite prepared based on fly ash, which is different from Example 1 in that the waste emulsion is omitted. The preparation method of this comparative example refers to Example 1.

[0079] Comparative Example 6: A lightweight and high-strength ceramsite based on fly ash, which is different from Example 1 in that the waste emulsion is adjusted to 10 parts by weight, and the other raw materials and parts by weight remain unchanged. The preparation method of this comparative example refers to Example 1.

[0080] Comparative Example 7: A lightweight and high-strength ceramsite based on fly ash, which is different from Example 1 in that diatomite is used to replace the pyrolysis residue of oil-containing diatomite, and the other parameters remain unchanged.

[0081] Comparative Example 8: A lightweight and high-strength ceramsite based on fly ash, which is different from Example 1 in that: the homogenization step is omitted in the preparation method, and at the same time, the mixing time in the stirring equipment is increased by 20 min.

[0082] Next, the content of the evaluation test will be described. Among them, the test items, index requirements and reference standards are shown in the following table: For the ceramsite prepared in the above Examples 1-6 and Comparative Examples 1-8, tests were carried out according to the regulations, and the results were averaged. The test results are recorded in Table 1 and Table 2 respectively.

[0083] Table 1 Performance test results of ceramsite in Examples 1-6 Table 1 results show that the present invention can prepare ceramsite with density grades of 500 kg / m 3 , 600 kg / m 3 , 700 kg / m 3 and 800 kg / m 3 At the same time, the cylinder compressive strength of the ceramsite of the corresponding density grade is more than 30% higher than the standard regulations, realizing an obvious improvement in strength under the same density grade, and at the same time, the product safety is guaranteed.

[0084] The bulk density of the ceramsite of the present invention ≤ 800 kg / m 3 , the 1h water absorption rate is between 6% and 10%, the cylinder compressive strength ≥ 6.0 MPa, the boiling mass loss ≤ 3.0%, the loss on ignition ≤ 4.2%, the content of sulfides and sulfates (calculated as SO3), the content of organic matter, the content of chlorides (calculated as chloride ion content) and the radioactivity all meet the regulations of GB / T17431.1.

[0085] Table 2 Performance test results of ceramsite in Comparative Examples 1-8 The results in Table 2 show that compared with Example 1, the density of the ceramsite in Comparative Example 1 increased, but the cylinder compressive strength did not increase significantly. Compared with Example 1, the density of the ceramsite in Comparative Example 2 decreased, but the decrease in the cylinder compressive strength was more obvious and did not achieve the expected effect. Compared with Example 1, the density of the ceramsite in Comparative Example 3 increased, but the produced ceramsite was brittle and the cylinder compressive strength decreased instead of increasing. Compared with Example 1, the density of the ceramsite in Comparative Example 4 decreased, and at the same time, the decrease in the cylinder compressive strength was more obvious. Compared with Example 1, although the density of the ceramsite in Comparative Example 5 increased, the cylinder compressive strength did not increase significantly and was inferior to that of the present invention. Compared with Example 1, the density of the ceramsite in Comparative Example 6 decreased significantly, and the cylinder compressive strength also decreased significantly at the same density level. Compared with Example 1, the density of the ceramsite in Comparative Example 7 increased, but the strength did not increase significantly and was inferior to that of the present invention. Compared with Example 1, both the density and the cylinder compressive strength of the ceramsite in Comparative Example 8 decreased significantly, indicating that homogenization is more beneficial to improving the properties of the ceramsite.

[0086] It can be seen that the synergistic disposal effect produced by preparing the ceramsite from fly ash, surface-treated sludge, coal gangue, contaminated soil or any mixture of the two, construction waste, pyrolysis residue of oil-containing diatomite and waste emulsion in the present invention is more significant, the comprehensive properties of the ceramsite are more remarkable, the matching of the preparation process and the components is scientific and reasonable, and a ceramsite product with higher cylinder compressive strength can be obtained at the same density level.

[0087] The ceramsite product prepared by the present invention can be used as a high-strength lightweight aggregate for building materials or other fields.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention shall be covered by the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A lightweight and high-strength ceramsite based on fly ash, characterized in that: The raw materials include the following parts by weight: 10-20 parts of fly ash, 5-10 parts of surface treatment sludge, 21-32 parts of coal gangue or contaminated soil or a mixture of the two in any proportion, 15-25 parts of construction waste, 10-17 parts of waste glass, 7-12 parts of oil-containing diatomaceous earth pyrolysis residue, and 3-6 parts of waste emulsion.

2. A fly ash-based lightweight high-strength ceramsite as claimed in claim 1, characterized in that: The construction waste contains the following chemical components in percentage by mass: SiO2 30-50%, CaO 5-15%, Al2O3 10-20%.

3. A fly ash-based lightweight high-strength ceramsite as claimed in claim 1, characterized in that: The mass percentage of SiO2 in the oil-containing diatomite pyrolysis residue is ≥60%.

4. A fly ash-based lightweight high-strength ceramsite as claimed in claim 1, characterized in that: The particle size of the fly ash, surface treated sludge, coal gangue or contaminated soil or a mixture of the two in any proportion, construction waste and oil-containing diatomaceous earth pyrolysis residue is ≤100 mesh.

5. A fly ash-based lightweight high-strength ceramsite according to any one of claims 1 to 4, characterized in that: Its effective ingredients and their mass percentages are: SiO2 50-60%, Al2O3 15-23%, Fe2O3 3-5%, CaO 10-13%, MgO 1-3%, Na2O 3-8%, and the CaO / SiO2 ratio is controlled at 0.2-0.

3.

6. A method for preparing a lightweight and high-strength ceramsite based on fly ash as claimed in claim 5, characterized in that: The following steps are involved: S1: fully mixing fly ash, surface treatment sludge, coal gangue or contaminated soil or a mixture of the two in any proportion, construction waste, oil-containing diatomaceous earth pyrolysis residue and waste emulsion in a stirring device to obtain a mixture; S2: conveying the mixed material to a homogenizer for pressurized homogenization to obtain a homogenized material; S3: conveying the homogenized material to a spray dryer for spray drying to obtain dry granules; S4: conveying the dry pellets to a high temperature sintering furnace, preheating the high temperature sintering furnace to 400-500° C., maintaining for 30-50 minutes, then heating to 1050-1150° C., maintaining for 20-40 minutes, cooling, and obtaining a product.

7. A method for preparing a lightweight and high-strength ceramsite based on fly ash as claimed in claim 6, characterized in that: The process parameters of the pressurized homogenization include: homogenization pressure of 30-35 MPa, homogenization temperature of 40-50° C., and homogenization time of 15-20 min.

8. The method for preparing a lightweight and high-strength ceramsite based on fly ash according to claim 6, characterized in that: The process parameters of the spray drying include: air inlet temperature of 200-230° C., air outlet temperature of 70-80° C., and spray pressure of 0.8-1.0 MPa.

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