High fly ash content fly ash sintering material, and preparation method and application thereof

Abstract

The present application relates to a kind of fly ash sintering material of high fly ash content and its preparation method and application.The method: silicon powder, alkali, water and dispersing agent are mixed and stirred at 75~95 ℃ for 4~12 h, to obtain special silicon aggregate solution;Sintering aid and waste incineration fly ash are mixed to obtain solid powder, then the solid powder and special silicon aggregate solution are placed in forming granulator to form granules, to obtain the shaped granules;Then calcine in high temperature treatment equipment at 600~900 ℃ for 0.2~1.2 h, to obtain the fly ash sintering material, the mass fraction of waste incineration fly ash in fly ash sintering material is 70~85%, and the mass fraction of sintering aid is 2~5%;The present application can realize high doping amount of waste incineration fly ash in fly ash sintering heat treatment process, and can reduce sintering temperature, the present application can obtain fly ash sintering material with heavy metal leaching toxicity reaching standard and strength reaching standard by low-temperature sintering treatment of high fly ash content waste incineration fly ash.

Description

Technical Field

[0001] This invention relates to the field of waste incineration fly ash disposal technology, and to a fly ash sintering material with high fly ash content, its preparation method, and its application. Background Technology

[0002] Fly ash from municipal solid waste incineration is a substance produced during the incineration of municipal solid waste and enters the flue gas purification system along with the flue gas, ultimately being collected by a dust collector. For grate-type waste incinerators, the output of fly ash is approximately 2-5% of the total waste fed into the furnace. Because fly ash is enriched with heavy metals such as Pb, Cd, Cu, Ni, and Zn, and also contains carcinogenic substances such as dioxins, it is classified as hazardous waste. Currently, the disposal methods for fly ash in domestic waste-to-energy plants remain at the stage of adding cement and stabilizers for solidification and landfilling, with resource utilization not yet on a large scale. Fly ash also contains abundant calcium and silicon resources, making its resource utilization significant. Fly ash washing in cement kilns is a relatively mature method for fly ash resource utilization, but the entire process is complex and costly. Sintering heat treatment of fly ash can achieve dioxin detoxification and is an effective means of realizing fly ash resource utilization. However, current fly ash sintering heat treatment processes generally suffer from problems such as low fly ash content and high sintering temperature. This is because existing fly ash sintering heat treatment processes can only obtain fly ash sintered materials that meet the standards for heavy metal stability and strength when using low fly ash content and high sintering temperature. This results in the high-temperature disposal cost still being much higher than the landfill disposal cost. Therefore, developing efficient and cost-effective fly ash sintering heat treatment technology is of great value and significance.

[0003] In summary, it is essential to provide a fly ash sinter with high fly ash content, its preparation method, and its application. Summary of the Invention

[0004] To address one or more technical problems existing in the prior art, this invention provides a high-fly ash content fly ash sintered material, its preparation method, and its application. This invention achieves low-sintering-temperature treatment of high-content waste incineration fly ash, and the resulting fly ash sintered material meets heavy metal leaching toxicity standards and possesses high strength.

[0005] The present invention provides a method for preparing fly ash sinter with high fly ash content in a first aspect, the method comprising the following steps:

[0006] (1) Mix silicon powder, alkali, water and dispersant evenly and stir at 75-95℃ for 4-12 hours to obtain a special silicon aggregate solution;

[0007] (2) The sintering aid and the fly ash from the waste incineration are mixed evenly to obtain solid powder. Then, the solid powder and the special silicon aggregate solution are placed together in a molding and granulation device to form granules and obtain shaped particles.

[0008] (3) The shaped granules are calcined at 600-900℃ for 0.2-1.2h in a high-temperature treatment equipment to obtain fly ash sinter with high fly ash content; the fly ash sinter contains 70-85wt% of waste incineration fly ash and 2-5wt% of sintering aids.

[0009] Preferably, in step (1): the alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0010] Preferably, in step (1): the dispersant is one or more of methyltriethoxysilane, propyltriethoxysilane, and sodium tripolyphosphate.

[0011] Preferably, in step (1), the mass ratio of the silicon powder, the alkali and the dispersant is 100:(5-15):(0.1-1.5).

[0012] Preferably, in step (1): the mass of water used is 3 to 6 times the mass of silicon powder used.

[0013] Preferably, the special silicon aggregate solution obtained in step (1) contains silicon dioxide with a particle size of 1 to 10 nm.

[0014] Preferably, in step (2): the sintering aid is one or more of calcium fluoride, boron powder, and borax with a particle size not greater than 100 nm.

[0015] Preferably, the compressive strength of the fly ash sinter with high fly ash content obtained in step (3) is not less than 4 MPa.

[0016] Preferably, the forming and granulating device includes a powder feeding plate, a liquid atomizer, a wet material feeding device, and a granulation and forming machine; a cavity is formed between the powder feeding plate, the liquid atomizer, and the wet material feeding device, the powder feeding plate is located above the cavity, the liquid atomizer is located circumferentially in the cavity, the wet material feeding device is located below the cavity, and the granulation and forming machine is located below the wet material feeding device; when forming and granulating using the forming and granulating device, the solid powder enters the cavity through the powder feeding plate, while the special silicon aggregate solution is atomized into liquid droplets by the liquid atomizer and enters the cavity. In the cavity, the liquid droplets fully contact and mix evenly with the solid powder to obtain wet material, and then the wet material enters the granulation and forming machine through the wet material feeding device to obtain shaped granules.

[0017] Preferably, the high-temperature treatment equipment includes a heating section cylinder at the top, a cooling section cylinder in the middle, and a solid material quenching tank at the bottom, connected in sequence. The heating section cylinder has an external heat insulation layer and an internal heating plate. The cooling section cylinder has an external cooling section jacket for the introduction of cooling medium. The top of the heating section cylinder has a waste gas outlet, a vacuum port, a gas inlet, and a solid material inlet. A porous partition is provided between the heating section cylinder and the cooling section cylinder. The bottom of the cooling section cylinder is the solid material outlet, which is connected to the solid material quenching pool. In step (3), after forming and granulating to obtain shaped particles, the shaped particles enter the heating section cylinder of the high-temperature treatment equipment through the solid material inlet and are heated to 600-900°C by the internal heating plate and calcined at 600-900°C for 0.2-1.2 hours. Then, they enter the cooling section cylinder through the porous partition to cool, and then enter the solid material quenching pool through the solid material outlet to quench, thereby obtaining fly ash sintered material with high fly ash content.

[0018] In a second aspect, the present invention provides a fly ash sinter with a high fly ash content prepared by the preparation method described in the first aspect of the present invention.

[0019] In a third aspect, the present invention provides the application of fly ash sintered material with high fly ash content prepared by the preparation method described in the first aspect of the present invention as a filler in building materials.

[0020] The present invention provides a granulation apparatus in a fourth aspect, the granulation apparatus comprising a powder feeding plate, a liquid atomizer, a wet material feeding device, and a granulation molding machine; a cavity is formed between the powder feeding plate, the liquid atomizer, and the wet material feeding device, the powder feeding plate being located above the cavity, the liquid atomizer being located circumferentially in the cavity, the wet material feeding device being located below the cavity, and the granulation molding machine being located below the wet material feeding device.

[0021] The present invention provides a high-temperature processing device in a fifth aspect. The high-temperature processing device includes a heating section cylinder located at the top, a cooling section cylinder located in the middle, and a solid material quenching tank located at the bottom, which are connected in sequence. The heating section cylinder is provided with a heat insulation layer on the outside and an internal heating plate on the inside. The cooling section cylinder is provided with a cooling section cylinder jacket for the introduction of a cooling medium on the outside. The top of the heating section cylinder is provided with an exhaust gas outlet, a vacuum port, a gas inlet, and a solid material inlet. A porous partition is provided between the heating section cylinder and the cooling section cylinder. The bottom of the cooling section cylinder is a solid material outlet, which is connected to the solid material quenching tank.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] This invention innovatively adds a self-made special silicon aggregate solution during the preparation of fly ash sintering material. The special silicon aggregate solution contains in-situ generated silicon dioxide with an extremely small particle size range (1 nm to 10 nm). This invention has found that the self-made special silicon aggregate exhibits extremely high activity, significantly superior to traditional silicon dioxide nanoparticles, effectively enhancing sintering activity. Simultaneously, the sintering aids selected in this invention are preferably calcium fluoride, boron powder, borax, etc., with a particle size not exceeding 100 nm, which also contribute to improving the sintering activity of waste incineration fly ash. The combination of the special silicon aggregate and the aforementioned sintering aids not only ensures high doping levels during fly ash sintering but also effectively reduces the sintering temperature. This invention, through low-temperature sintering of high-doped waste incineration fly ash, can prepare fly ash sintering material that meets the standards for heavy metal leaching toxicity and strength. Compared with traditional methods, this invention has significant efficiency and cost advantages, not only greatly reducing process costs but also possessing the potential for industrial-scale application. This invention also employs a novel molding equipment (molding and granulation device) to process materials, effectively achieving uniform mixing of powdered materials (solid powder) and liquid materials (special silicon aggregate solution), thus improving molding density and uniformity. In this invention, solid powder and special silicon aggregate solution are uniformly mixed before molding, granulation, and calcination, which is beneficial for improving the heavy metal stabilization and sintering uniformity of the prepared fly ash sinter. Conventional molding and granulation devices usually require other mixing equipment to achieve mixing between solids and liquids, and often suffer from uneven mixing. This invention also employs a novel heat treatment device (high-temperature treatment device) to heat-treat (calcine at high temperature) the shaped granules after molding, achieving internal heating of the solid material (shaped granules) with high heating efficiency. Common sintering equipment is generally a rotary kiln, which is very long, occupies a large area, and has a material filling rate of less than 30%. In contrast, the high-temperature treatment device in this invention can achieve a 100% filling rate, has a smaller footprint, higher thermal efficiency, and more complete sintering, which also helps improve the heavy metal stabilization effect of fly ash sinter. Overall, this invention provides a fly ash sintering heat treatment technology with significant practical value, combining environmental and economic benefits, and has broad application prospects in the field of solid waste treatment. Attached Figure Description

[0024] The accompanying drawings are provided for illustrative purposes only, and the proportions, dimensions, and quantities of the parts in the drawings may not be consistent with the actual product.

[0025] Figure 1 This is a flowchart illustrating the preparation process of fly ash sintered material in some specific embodiments of the present invention.

[0026] Figure 2 A schematic diagram of the granulation and forming device provided by the present invention; in the figure, 81: powder feeding plate; 82: liquid atomizer; 83: wet material feeding device; 84: granulation and forming machine;

[0027] Figure 3 The diagram shows the structure of the high-temperature processing equipment provided by the present invention. In the diagram, 1: heat insulation layer of the heating section cylinder; 2: cooling medium outlet of the cooling section cylinder jacket; 3: cooling medium inlet of the cooling section cylinder jacket; 4: solid material outlet; 5: solid material quenching pool; 6: porous partition; 7: internal heating plate; 8: exhaust gas outlet; 9: vacuum port; 10: gas inlet; 11: solid material inlet. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] In a first aspect, this invention provides a method for preparing fly ash sinter with high fly ash content, the preparation process being as follows: Figure 1 As shown, the method includes the following steps:

[0030] (1) Mix silicon powder, alkali, water and dispersant evenly and stir at 75-95℃ (e.g. 75℃, 80℃, 85℃, 90℃ or 95℃) for 4-12 hours (e.g. 4, 5, 6, 7, 8, 9, 10, 11 or 12 hours) to obtain a special silicon aggregate solution; the present invention does not have special requirements on the particle size of silicon powder, for example, silicon powder with a mesh size of 400 or larger can be selected;

[0031] (2) The sintering aid and the fly ash from the waste incineration are mixed evenly to obtain a solid powder. Then, the solid powder and the special silicon aggregate solution are placed together in a molding and granulation device to form and granulate the powder to obtain shaped particles. In this invention, for example, shaped particles with a size of less than 30 mm are obtained by molding and granulation.

[0032] (3) The shaped granules are calcined in a high-temperature treatment device at 600–900℃ (e.g., 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃) for 0.2–1.2 h (e.g., 0.2, 0.5, 0.8, 1 or 1.2 h) to obtain fly ash sinter with high fly ash content (abbreviated as fly ash sinter); the fly ash sinter contains 70–85% fly ash by mass of waste incineration fly ash. wt% (e.g., 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt%, 82wt%, 83wt%, 84wt%, or 85wt%), containing sintering aids at a mass fraction of 2–5wt% (e.g., 2wt%, 3wt%, 4wt%, or 5wt%); in this In this invention, the fly ash sintering material contains a total mass percentage of 100% of incineration fly ash, sintering aid, and special silicon aggregates. In this invention, high fly ash content refers to the fly ash sintering material containing 70-85 wt% of incineration fly ash. In this invention, the calcination temperature is low, only 600-900℃, while in conventional fly ash sintering heat treatment, the calcination temperature is generally higher than 1100℃, and the fly ash content is generally not higher than 50 wt%. In this invention, the special silicon aggregate solution contains water, and the high fly ash sintering material obtained after calcination does not contain water. Based on the water content in the special silicon aggregate and the contents of incineration fly ash, sintering aid, and special silicon aggregates in the fly ash sintering material, the dosage ratio of sintering aid, incineration fly ash, and special silicon aggregate solution in step (2) can be determined.

[0033] In preparing fly ash sintering material, this invention innovatively adds a self-made special silicon aggregate solution. The special silicon aggregate solution contains in-situ generated silicon dioxide with an extremely small particle size range (1nm~10nm). This invention has found that the self-made special silicon aggregate has extremely high activity, significantly better than traditional silicon dioxide nanoparticles, and can effectively improve sintering activity. The combination of the special silicon aggregate and the sintering aid not only ensures high doping levels during fly ash sintering but also effectively reduces the sintering temperature. This invention utilizes low-temperature sintering to treat high-doped waste incineration fly ash, producing fly ash sintered materials with acceptable heavy metal leaching values ​​and strength. Specifically, it significantly reduces the leaching values ​​of severely excessive Pb and Cd in waste incineration fly ash. This invention reduces the Pb (lead) leaching value in the fly ash sintered material by over 98.4% compared to the original Pb leaching value, and reduces the Cd (cadmium) leaching value by over 99%. Furthermore, this invention ensures that the compressive strength of the fly ash sintered material is not less than 4 MPa. Compared to traditional methods, this invention offers significant efficiency and cost advantages, not only substantially reducing process costs but also possessing the potential for industrial-scale application. Overall, this invention provides a fly ash sintering heat treatment technology with significant practical value, combining environmental and economic benefits, and has broad application prospects in the field of solid waste treatment.

[0034] In the preparation of the special silicon aggregate solution, the present invention controls the reaction temperature to 75–95°C and the reaction time to 4–12 hours to ensure the formation of extremely small (1 nm to 10 nm) and uniform special silicon aggregates with high activity. The present invention has found that reacting at 75–95°C for 4–12 hours effectively promotes the aggregation of silica and the formation of nanoparticles. If the reaction temperature is too low, the reaction rate will be slow, which is not conducive to the formation of highly active special silicon aggregates. If the reaction temperature is too high, the reaction will be too fast, the particles will grow rapidly, and the silica particles may quickly aggregate and form large agglomerates, making it difficult to control the particle size and uniformity. If the reaction time is too short, the formation of special silicon aggregates will be insufficient, resulting in uneven particle size and incomplete reaction. If the reaction time is too long, the special silicon aggregates may begin to re-aggregate, forming larger particles, destroying the uniform nanostructure, affecting the activity of the special silicon aggregates, and consequently affecting the sintering activity of waste incineration fly ash.

[0035] According to some preferred embodiments, in step (1): the alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0036] According to some preferred embodiments, in step (1): the dispersant is one or more of methyltriethoxysilane, propyltriethoxysilane, and sodium tripolyphosphate.

[0037] According to some preferred embodiments, in step (1), the mass ratio of the silicon powder, the alkali and the dispersant is 100:(5-15):(0.1-1.5) (e.g., 100:5:0.1, 100:5:0.5, 100:5:1, 100:5:1.5, 100:10:0.1, 100:10:0.5, 100:10:1, 100:10:1.5, 100:15:0.1, 100:15:0.5, 100:15:1 or 100:15:1.5), preferably 100:(5-10):(0.1-1.5).

[0038] According to some preferred embodiments, in step (1): the mass of water used is 3 to 6 times (e.g., 3, 4, 5 or 6 times) the mass of silicon powder used.

[0039] In this invention, preferably, during the preparation of the special silicon aggregate solution, the mass ratio of silicon powder, alkali, and dispersant is controlled to be 100:(5-15):(0.1-1.5), and the mass of water is 3-6 times the mass of silicon powder. This helps to generate special silicon aggregates with extremely small (1nm to 10nm) and uniform particle size and high activity. The possible reason is that if the amount of alkali is too small, the silicon powder cannot react sufficiently, resulting in a large amount of unreacted silicon powder and a low yield of special silicon aggregates. If the amount of alkali is too large, it will lead to the formation of irregular or large silica agglomerates, destroying the originally designed small particle size structure and affecting sintering activity. The role of the dispersant is to prevent the silica nanoparticles generated during the reaction from agglomerating. Aggregation is crucial for maintaining uniform particle dispersion. Insufficient dispersant can lead to agglomeration of nanoparticles, resulting in increased particle size and reduced sintering activity. Conversely, excessive dispersant may affect the stability of the reaction system, making it difficult to control the reaction process and hindering the formation of small-sized aggregates. Appropriate dispersant dosage effectively prevents agglomeration and maintains stable dispersion of nanoparticles. The addition of an appropriate amount of water ensures a suitable reaction concentration and a good mass transfer environment, which is beneficial for forming the desired particle size range and structure. In this invention, the use of the aforementioned special silicon aggregate solution for sintering waste incineration fly ash significantly improves sintering activity and facilitates the production of fly ash sinter that meets the standards for heavy metal leaching toxicity and strength.

[0040] According to some preferred embodiments, the special silicon aggregate solution obtained in step (1) contains silicon dioxide with a particle size of 1 to 10 nm.

[0041] According to some preferred embodiments, in step (2): the sintering aid is one or more of calcium fluoride, boron powder, and borax with a particle size of not more than 100 nm; in this invention, it is preferred that the sintering aid is one or more of calcium fluoride, boron powder, and borax with a particle size of not more than 100 nm, which also helps to improve the sintering activity of waste incineration fly ash.

[0042] According to some preferred embodiments, the compressive strength of the fly ash sinter with high fly ash content obtained in step (3) is not less than 4 MPa.

[0043] According to some preferred embodiments, the granulation apparatus includes a powder feeding plate 81, a liquid atomizer 82, a wet material feeding device 83, and a granulation and molding machine 84, for example... Figure 2 As shown; a cavity is formed between the powder feeding plate 81, the liquid atomizer 82, and the wet material feeding device 83. The powder feeding plate 81 is located above the cavity, the liquid atomizer 82 is located circumferentially within the cavity, and the liquid atomizer 82 is used to atomize the special silicon aggregate solution into droplets to form liquid droplets. The wet material feeding device 83 is located below the cavity, and the granulation and molding machine 84 is located below the wet material feeding device 83. In this invention, using as... Figure 2 The granulation device shown in the invention employs the following process: the solid powder enters the cavity through a powder feeding plate, while the special silicon aggregate solution is atomized into liquid droplets by a liquid atomizer and enters the cavity. In the cavity, the liquid droplets fully contact and mix evenly with the solid powder to obtain a wet material. This wet material is then fed into a granulation and molding machine via a wet material feeding device to form granules. In this invention, the granulation and molding machine can be an extrusion granulator. The granulation and molding device used in this invention is a highly efficient solid-liquid mixing granulation preparation device, which significantly improves the uniformity of the granules and enhances the density and uniformity of the granulation. This invention achieves uniform mixing of the solid powder with the special silicon aggregate solution before granulation and calcination, which is beneficial for improving the heavy metal stabilization and sintering uniformity of the prepared fly ash sinter.

[0044] According to some preferred embodiments, the high-temperature treatment equipment includes a heating section cylinder at the top, a cooling section cylinder in the middle, and a solid material quenching tank 5 at the bottom, connected in sequence. For example, Figure 3As shown, the heating section cylinder is provided with a heat insulation layer 1 on the outside, an internal heating plate 7 on the inside, and a cooling section cylinder jacket for the cooling medium to pass through on the outside; the top of the heating section cylinder is provided with an exhaust port 8, a vacuum port 9, a gas inlet 10, and a solid material inlet 11; a perforated partition 6 is provided between the heating section cylinder and the cooling section cylinder, and the bottom of the cooling section cylinder is a solid material outlet 4, which is connected to the solid material quenching pool 5; in step (3), the solid material is obtained by molding and granulation. After granulation, the shaped granules enter the heating section cylinder of the high-temperature treatment equipment through the solid material inlet. They are heated to 600–900°C by internal heating plates and calcined at 600–900°C for 0.2–1.2 hours. Then, they pass through a porous baffle into the cooling section cylinder for cooling, and finally enter the solid material quenching pool through the solid material outlet for further quenching, resulting in high-fly ash sintered material. In this invention, the upper part of the cooling section cylinder jacket is provided with a cooling medium outlet 2, and the lower part of the cooling section cylinder jacket is provided with a cooling medium inlet 3. This invention utilizes a cooling medium and internal heating... The type of plate, porous partition, etc., is not specifically limited and can be conventionally selected by those skilled in the art. In this invention, the holes in the porous partition are evenly distributed. In this invention, the exhaust port, vacuum port, gas inlet, and solid material inlet can be arranged sequentially from left to right at the top of the heating section cylinder. In this invention, multiple internal heating plates can be provided, such that they are evenly distributed inside the heating section cylinder. Preferably, the upper end of the internal heating plate is connected to the inner top of the heating section cylinder, and the internal heating plate is also connected to a heating power supply. The internal heating plate can heat the solid material (formed particles) from the inside, improving heating efficiency. In this invention, the gas inlet can be used to introduce atmospheres such as nitrogen, argon, and carbon dioxide, enabling atmosphere calcination. The high-temperature treatment equipment also has a vacuum port connected to an external vacuum system, enabling internal atmosphere control of the high-temperature treatment equipment, which is very beneficial for controlling the calcination atmosphere during the calcination process. This novel high-temperature heat treatment equipment can effectively improve the efficiency of the heat treatment process (calcination process) and reduce process energy consumption.

[0045] In a second aspect, the present invention provides a fly ash sinter with a high fly ash content prepared by the preparation method described in the first aspect of the present invention.

[0046] In a third aspect, the present invention provides the application of fly ash sinter with high fly ash content prepared by the preparation method described in the first aspect of the present invention as a filler in building materials; specifically, for example, it can be used as a filler in concrete materials, such as aggregates.

[0047] In a fourth aspect, the present invention provides a molding and granulation apparatus, for example, such as... Figure 2 As shown, the granulation device includes a powder feeding plate 81, a liquid atomizer 82, a wet material feeding device 83, and a granulation molding machine 84. A cavity is formed between the powder feeding plate 81, the liquid atomizer 82, and the wet material feeding device 83. The powder feeding plate 81 is located above the cavity, the liquid atomizer 82 is located circumferentially around the cavity, the wet material feeding device 83 is located below the cavity, and the granulation molding machine 84 is located below the wet material feeding device 83. In this invention, the granulation molding machine can be an extrusion granulator. This invention provides a highly efficient solid-liquid mixing granulation preparation device, which significantly improves the uniformity of the granulated particles.

[0048] In a fifth aspect, the present invention provides a high-temperature processing apparatus, for example, such as... Figure 3 As shown, the high-temperature treatment equipment includes a heating section cylinder at the top, a cooling section cylinder in the middle, and a solid material quenching tank 5 at the bottom, connected in sequence. The heating section cylinder has an external heat insulation layer 1 and an internal heating plate 7. The cooling section cylinder has an external cooling section jacket for the cooling medium to pass through. The top of the heating section cylinder has a waste gas outlet 8, a vacuum port 9, a gas inlet 10, and a solid material inlet 11. A perforated partition 6 is provided between the heating section cylinder and the cooling section cylinder. The bottom of the cooling section cylinder is a solid material outlet 4, which is connected to the solid material quenching tank 5. In this invention, the upper part of the cooling section jacket also has a cooling medium outlet 2, and the lower part of the cooling section jacket also has a cooling... Medium inlet 3; In this invention, the exhaust port, vacuum port, gas inlet, and solid material inlet can be sequentially arranged from left to right at the top of the heating section cylinder; In this invention, multiple internal heating plates can be provided, such that the multiple internal heating plates are evenly distributed inside the heating section cylinder. Preferably, the upper end of the internal heating plate is connected to the inner top of the heating section cylinder, and the internal heating plate is also connected to a heating power supply. The internal heating plate can realize the internal heating of solid materials, thereby improving heating efficiency; In this invention, the gas inlet can be used to introduce atmospheres such as nitrogen, argon, and carbon dioxide, which can realize the atmosphere calcination function. At the same time, the high-temperature treatment equipment also has a vacuum port, which is connected to an external vacuum system, enabling the internal atmosphere control of the high-temperature treatment equipment. This invention provides a novel high-temperature heat treatment equipment that can effectively improve the efficiency of the heat treatment process (calcination process) and reduce process energy consumption.

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Example 1

[0051] This embodiment provides a method for preparing fly ash sinter with high fly ash content, including the following steps:

[0052] ① Mix silicon powder, alkali, water and dispersant evenly and stir at 85°C for 5 hours to obtain a special silicon aggregate solution; wherein, the alkali is sodium hydroxide, the dispersant is methyltriethoxysilane, and the mass ratio of silicon powder, sodium hydroxide and methyltriethoxysilane is 100:8:1; the mass amount of water is 4 times the mass amount of silicon powder; the special silicon aggregate solution obtained in step ① contains silicon dioxide with a particle size (average particle size) of 1.8 nm.

[0053] ② Mix the sintering aid (boron powder with an average particle size of 100 nm) and the waste incineration fly ash (municipal solid waste incineration fly ash) evenly to obtain a solid powder; place the solid powder together with the special silicon aggregate solution obtained in step ① in a container as follows: Figure 2 The granulation apparatus shown is used for granulation to obtain shaped granules.

[0054] ③ The shaped particles obtained in step ② are placed in, for example... Figure 3 The fly ash sintered material with high fly ash content was obtained by calcining in a nitrogen atmosphere at 600°C for 1.2 hours in the high-temperature treatment equipment shown. The obtained fly ash sintered material contains 70 wt% fly ash from waste incineration, 2 wt% sintering aids, and 28 wt% special silicon aggregates.

[0055] Example 2

[0056] This embodiment provides a method for preparing fly ash sinter with high fly ash content, including the following steps:

[0057] ① Mix silicon powder, alkali, water and dispersant evenly and stir at 85°C for 5 hours to obtain a special silicon aggregate solution; wherein, the alkali is sodium hydroxide, the dispersant is methyltriethoxysilane, and the mass ratio of silicon powder, sodium hydroxide and methyltriethoxysilane is 100:8:1; the mass amount of water is 4 times the mass amount of silicon powder; the special silicon aggregate solution obtained in step ① contains silicon dioxide with a particle size (average particle size) of 1.8 nm.

[0058] ② Mix the sintering aid (boron powder with an average particle size of 100 nm) and the waste incineration fly ash (municipal solid waste incineration fly ash) evenly to obtain a solid powder; place the solid powder together with the special silicon aggregate solution obtained in step ① in a container as follows: Figure 2 The granulation apparatus shown is used for granulation to obtain shaped granules.

[0059] ③ The shaped particles obtained in step ② are placed in, for example... Figure 3 The fly ash sintered material with high fly ash content was obtained by calcining in a nitrogen atmosphere at 750°C for 1 hour in the high-temperature treatment equipment shown. The obtained fly ash sintered material contains 78 wt% fly ash from waste incineration, 4 wt% sintering aids, and 18 wt% special silicon aggregates.

[0060] Example 3

[0061] This embodiment provides a method for preparing fly ash sinter with high fly ash content, including the following steps:

[0062] ① Mix silicon powder, alkali, water and dispersant evenly and stir at 85°C for 5 hours to obtain a special silicon aggregate solution; wherein, the alkali is sodium hydroxide, the dispersant is methyltriethoxysilane, and the mass ratio of silicon powder, sodium hydroxide and methyltriethoxysilane is 100:8:1; the mass amount of water is 4 times the mass amount of silicon powder; the special silicon aggregate solution obtained in step ① contains silicon dioxide with a particle size (average particle size) of 1.8 nm.

[0063] ② Mix the sintering aid (boron powder with an average particle size of 100 nm) and the waste incineration fly ash (municipal solid waste incineration fly ash) evenly to obtain a solid powder; place the solid powder together with the special silicon aggregate solution obtained in step ① in a container as follows: Figure 2 The granulation apparatus shown is used for granulation to obtain shaped granules.

[0064] ③ The shaped particles obtained in step ② are placed in, for example... Figure 3 The fly ash sintered material with high fly ash content was obtained by calcining in a nitrogen atmosphere at 900℃ for 1 hour in the high-temperature treatment equipment shown. The fly ash sintered material contains 85 wt% fly ash from waste incineration, 5 wt% sintering aid, and 10 wt% special silicon aggregate.

[0065] Comparative Example 1

[0066] ① Mix the sintering aid (boron powder with an average particle size of 100nm), waste incineration fly ash (municipal solid waste incineration fly ash) and silicon micro powder evenly to obtain solid powder; granulate the solid powder in a conventional extrusion granulator to obtain shaped particles.

[0067] ② The shaped particles are calcined in a conventional rotary kiln at 750°C under a nitrogen atmosphere for 1 hour to obtain fly ash sintered material; the fly ash sintered material contains 78 wt% of waste incineration fly ash, 4 wt% of sintering aid, and 18 wt% of silica fume.

[0068] Comparative Example 2

[0069] ① A solid powder is obtained by uniformly mixing sintering aid (boron powder with an average particle size of 100nm), waste incineration fly ash (municipal solid waste incineration fly ash) and silica nanoparticles (average particle size of 50nm); the solid powder is granulated in a conventional extrusion granulator to obtain shaped granules.

[0070] ② The shaped particles are calcined in a conventional rotary kiln at 750°C under a nitrogen atmosphere for 1 hour to obtain fly ash sintered material; the fly ash sintered material contains 78 wt% of waste incineration fly ash, 4 wt% of sintering aid, and 18 wt% of silica nanoparticles.

[0071] Comparative Example 3

[0072] ① A solid powder is obtained by uniformly mixing a sintering aid (boron powder with an average particle size of 100 nm) and waste incineration fly ash (municipal solid waste incineration fly ash); the solid powder is granulated in a conventional extrusion granulator to obtain shaped particles; in the shaped particles, the mass ratio of waste incineration fly ash to sintering aid is 78:4.

[0073] ② The shaped particles are calcined in a conventional rotary kiln at 750°C under a nitrogen atmosphere for 1 hour to obtain fly ash sintered material.

[0074] The present invention tested the heavy metal leaching concentration (mg / mL) and compressive strength (MPa) of the fly ash obtained from waste incineration fly ash, Examples 1-3, and Comparative Examples 1-3. The results are shown in Table 1. The heavy metal leaching concentration was tested according to the solid waste leaching toxicity leaching method - acetic acid buffer solution method HJ / T300-2007 as specified in standard GB16889-2008.

[0075] Table 1

[0076]

[0077]

[0078] In Table 1, the symbol " / " indicates that the indicator does not exist or cannot be measured.

[0079] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0080] It should be noted that the terms "upper," "lower," "bottom," "top," "inner," and "outer," etc., indicate the direction or positional relationship based on the appendix. Figure 2 and attached Figure 3 The orientations or positional relationships shown are merely for the convenience of describing the invention and for simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of the invention, it should also be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection, an indirect connection through an intermediate medium, or a continuous connection, etc. Those skilled in the art can understand the specific meaning of this term in the invention according to the specific circumstances.

[0081] Finally, it should be noted that: the above provides a detailed description of the high fly ash content fly ash sinter, preparation method, and application disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing fly ash sinter with high fly ash content, characterized in that, The method includes the following steps: (1) Mix silicon powder, alkali, water and dispersant evenly and stir at 75~95℃ for 4~12h to obtain a special silicon aggregate solution; (2) The sintering aid and the fly ash from the waste incineration are mixed evenly to obtain a solid powder. Then, the solid powder and the special silicon aggregate solution are placed together in a granulation device to form granules and obtain shaped particles. The granulation device includes a powder feeding plate, a liquid atomizer, a wet material feeding device, and a granulation molding machine. A cavity is formed between the powder feeding plate, the liquid atomizer, and the wet material feeding device. The powder feeding plate is located above the cavity, the liquid atomizer is located around the cavity, the wet material feeding device is located below the cavity, and the granulation molding machine is located below the wet material feeding device. When granulating using the granulation device, the solid powder enters the cavity through the powder feeding plate, while the special silicon aggregate solution is atomized into liquid droplets by the liquid atomizer and enters the cavity. In the cavity, the liquid droplets fully contact and mix evenly with the solid powder to obtain wet material. Then, the wet material enters the granulation and molding machine through the wet material feeding device to form granules. (3) The shaped particles are calcined at 600~900℃ for 0.2~1.2h in a high-temperature treatment equipment to obtain fly ash sinter with high fly ash content; the fly ash sinter contains 70~85wt% of waste incineration fly ash and 2~5wt% of sintering aid.

2. The preparation method according to claim 1, characterized in that, In step (1): The alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide; The dispersant is one or more of methyltriethoxysilane, propyltriethoxysilane, and sodium tripolyphosphate; The mass ratio of the silicon powder, the alkali, and the dispersant is 100:(5~15):(0.1~1.5). The amount of water used is 3 to 6 times the amount of silicon powder used; and / or The special silicon aggregate solution obtained in step (1) contains silicon dioxide with a particle size of 1~10nm.

3. The preparation method according to claim 1, characterized in that, In step (2): The sintering aid is one or more of calcium fluoride, boron powder, and borax with a particle size of no more than 100 nm.

4. The preparation method according to claim 1, characterized in that: The compressive strength of the fly ash sinter with high fly ash content obtained in step (3) is not less than 4 MPa.

5. The preparation method according to claim 1, characterized in that: The high-temperature treatment equipment includes a heating section cylinder at the top, a cooling section cylinder in the middle, and a solid material quenching tank at the bottom, connected in sequence. The heating section cylinder has an external heat insulation layer and an internal heating plate. The cooling section cylinder has an external cooling section jacket for the introduction of cooling medium. The top of the heating section cylinder has a waste gas outlet, a vacuum port, a gas inlet, and a solid material inlet. A perforated partition is provided between the heating section cylinder and the cooling section cylinder. The bottom of the cooling section cylinder is a solid material outlet, which is connected to the solid material quenching tank. In step (3), after the shaped granules are obtained by molding and granulation, the shaped granules enter the heating section cylinder of the high-temperature treatment equipment through the solid material inlet and are heated to 600~900℃ by the internal heating plate and calcined at 600~900℃ for 0.2~1.2h. Then, they enter the cooling section cylinder through the porous partition and are cooled. Finally, they enter the solid material quenching pool through the solid material outlet to quench and obtain fly ash sinter with high fly ash content.

6. A fly ash sinter with high fly ash content, characterized in that: The fly ash sinter with high fly ash content is prepared by the preparation method according to any one of claims 1 to 5.

7. An application of a fly ash sinter with high fly ash content, characterized in that: The high fly ash content fly ash sinter is prepared by the preparation method according to any one of claims 1 to 5, and the high fly ash content fly ash sinter is used as a filler in building materials.

8. A pelletizing apparatus, characterized in that: Used to implement the preparation method according to any one of claims 1 to 5; The granulation and molding device includes a powder feeding plate, a liquid atomizer, a wet material feeding device, and a granulation and molding machine. A cavity is formed between the powder feeding plate, the liquid atomizer, and the wet material feeding device. The powder feeding plate is located above the cavity, the liquid atomizer is located circumferentially in the cavity, the wet material feeding device is located below the cavity, and the granulation molding machine is located below the wet material feeding device.

9. A high-temperature treatment device, characterized in that: Used to implement the preparation method according to any one of claims 1 to 5; The high-temperature treatment equipment includes a heating section cylinder at the top, a cooling section cylinder in the middle, and a solid material quenching tank at the bottom, connected in sequence. The heating section cylinder is provided with a heat insulation layer on the outside and an internal heating plate on the inside. The cooling section cylinder is provided with a cooling section jacket for the cooling medium to pass through. The top of the heating section cylinder is provided with an exhaust port, a vacuum port, a gas inlet, and a solid material inlet. A porous baffle is provided between the heating section cylinder and the cooling section cylinder. The bottom of the cooling section cylinder is a solid material outlet, which is connected to the solid material quenching tank.

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