A method for preparing artificial cenospheres using fly ash, a solid waste.

Abstract

This invention belongs to the field of solid waste treatment technology, specifically disclosing a method for preparing artificial cenospheres using solid waste fly ash. The method involves weighing solid waste fly ash, a high-temperature foaming agent, a modifier, and an adhesive, mixing them evenly, and drying the mixture. The resulting mixture is then granulated to form artificial cenosphere blanks. The dried artificial cenosphere blanks are placed in a vortex expansion vitrification furnace for heat treatment. During this process, the modifier transforms into a liquid phase at high temperature and fills the pores of the microspheres. Simultaneously, the gas generated by the high-temperature foaming agent increases the internal pressure of the blank and promotes the formation of a porous structure within the microspheres. Finally, the blanks are cooled in the furnace, resulting in artificial cenospheres with a porous internal structure and a dense, hard glaze layer on the surface. This method is simple, low-cost, and suitable for industrial production. The implementation of this method requires the consumption of a large amount of solid waste fly ash, thus reusing the waste and effectively solving the environmental pollution problem caused by the large accumulation of solid waste fly ash.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, and specifically discloses a method for preparing artificial cenospheres using fly ash, a solid waste. Background Technology

[0002] Fly ash typically refers to the solid waste obtained by power plants through collection equipment after coal combustion.

[0003] Chinese patent (CN200910023179.1) discloses a method for preparing ceramsite using fly ash. In this method, the proportion of fly ash used is between 30% and 50%, and the firing temperature range is 1200 to 1300°C. The fly ash ceramsite prepared by this method has a compressive strength as high as 120 MPa. However, the fly ash content used in this invention is relatively small.

[0004] Chinese patent (201510148929.3) discloses a method for preparing lightweight ceramsite using fly ash and gasification slag, and its application. This technology uses fly ash, gasification slag, potassium-sodium feldspar, and additives as raw materials, and fires them at a high temperature of 1120–1200℃ to obtain a bulk density as high as 700 kg / m³. 3 Furthermore, lightweight ceramsite with a compressive strength reaching 10 MPa has been obtained. Chinese Patent (CN202210952343.2) discloses a method for preparing self-foaming sintered ceramsite. This method involves mixing 50-70% copper tailings, 15-35% fly ash, 5-20% high-ferrous phase solid waste foaming agent, and 3-5% fluxing agent, stirring the mixture into pellets, and then sintering them under an inert atmosphere. In addition, this method also utilizes the high-temperature decomposition reaction of +3 valent Fe compounds in red mud to prepare in-situ self-foaming lightweight ceramsite. The final lightweight ceramsite has a bulk density of 0.47-0.73 g / cm³. 3 The single-particle strength is 4.28–13.15 MPa. This invention of sintered ceramsite provides an important technical reference for the building materials industry to further develop towards lightweight and high-strength materials, and provides a feasible route for the green development of industrial metallurgical engineering and the materials industry. Chinese Patent (CN202011449619.2) discloses a fly ash ceramsite and its preparation method. The method uses polyvinyl alcohol, sodium- or potassium-containing compounds, fly ash and sludge as raw materials, and prepares ceramsite with a strength of 6.5–8.5 MPa and a strength of 450–750 kg / m³ through a cylinder pressing process. 3 The bulk density of fly ash ceramsite is high, however, the ceramsite prepared by the above invention has a high bulk density and cannot replace cenospheres.

[0005] By utilizing fly ash to prepare artificial cenospheres, the problem of large-scale fly ash accumulation can be perfectly solved. Cenospheres are a new type of multifunctional material with wide applications in drinking water treatment, wastewater treatment, thermal insulation materials, sound insulation materials, and catalyst carriers. Currently, the annual demand for cenospheres has reached 12-15 million cubic meters. 3 Furthermore, it continues to grow at a rate of approximately 20% annually, indicating a huge market demand. Using fly ash to produce artificial cenospheres not only reduces costs but also eliminates the hazards caused by the large-scale accumulation of solid waste fly ash. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a method for preparing artificial cenospheres using solid waste fly ash. The method involves mixing solid waste fly ash with a high-temperature foaming agent, a modifier, and an adhesive. The mixture is then granulated to form an artificial cenosphere blank. After heat treatment and cooling, artificial cenospheres with a porous internal structure and a dense, hard glaze layer on the surface are obtained, effectively solving the environmental pollution problem caused by the accumulation of solid waste fly ash.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A method for preparing artificial cenospheres using fly ash, a solid waste, includes the following steps:

[0009] (1) Weigh solid waste fly ash, high-temperature foaming agent, modifier and adhesive according to the raw material ratio, mix evenly, dry to obtain a mixture with moisture content of less than 3.0%. The role of adhesive is to improve the strength of microsphere blank, while the role of modifier is to reduce the bulk density of blank.

[0010] (2) The mixture obtained in step (1) is made into artificial cenosphere blanks by granulation process;

[0011] (3) The dried artificial bead blank is placed in a vortex expansion vitrification furnace for heat treatment. During this process, the modifier is transformed into a liquid phase at high temperature and fills the microsphere pores. At the same time, the gas generated by the high temperature foaming agent increases the internal pressure of the blank and promotes the formation of a porous structure inside the microsphere. Finally, it is cooled with the furnace to obtain artificial bead with a porous internal structure and a dense and hard glaze layer on the surface.

[0012] Furthermore, the method for preparing artificial cenospheres using solid waste fly ash comprises the following raw material proportions by weight: 65-85 parts solid waste fly ash, 0-10 parts high-temperature foaming agent, 15-30 parts modifier, and 0-3 parts adhesive.

[0013] Furthermore, in the method for preparing artificial cenospheres using fly ash, the fly ash refers to the solid waste obtained by collecting fine ash particles produced after coal combustion in coal-fired power plants. The particle size of the solid waste is less than 80 μm, and the silica content in the solid waste is greater than 38%.

[0014] Furthermore, in the method for preparing artificial cenospheres using fly ash, a solid waste, the high-temperature foaming agent is silicon carbide powder with a particle size of less than 25 μm.

[0015] Furthermore, in the method for preparing artificial cenospheres using fly ash, a solid waste, the modifier is a composite powder of glass powder and perlite powder mixed in a mass ratio of 1 to 1.5:1, with a particle size of less than 25 μm.

[0016] Furthermore, in the method for preparing artificial cenospheres using fly ash, a solid waste, the adhesive refers to dextrin and / or carboxymethyl cellulose.

[0017] Furthermore, in the method for preparing artificial cenospheres using solid waste fly ash, the granulation process in step (2) adopts extrusion granulation, stirring granulation, or spray drying granulation.

[0018] Furthermore, in the method for preparing artificial cenospheres using solid waste fly ash, in step (3), the artificial cenosphere blank is placed in a vortex expansion vitrification furnace for heat treatment at a temperature of 1150℃~1250℃. During this process, the modifier is converted into a liquid phase at high temperature and fills the microsphere pores. At the same time, the gas generated by the high-temperature foaming agent increases the internal pressure of the blank and promotes the formation of a porous structure inside the microsphere. Finally, the blank is cooled with the furnace to obtain artificial cenospheres with a porous internal structure and a dense and hard glaze layer on the surface.

[0019] Furthermore, in the method for preparing artificial cenospheres using solid waste fly ash, in step (3), when the artificial cenosphere blank is placed in a vortex expansion vitrification furnace for heat treatment, the heat treatment heating process is as follows: room temperature to 100℃, 2.5℃ / min; 100℃ to 1200℃, 6℃ / min; 1200℃ to 1250℃, 1℃ / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention discloses a method for preparing artificial cenospheres using solid waste fly ash. First, solid waste fly ash, a high-temperature foaming agent, a modifier, and an adhesive are weighed according to the raw material ratio, mixed evenly, and dried. The resulting mixture is then granulated to form artificial cenosphere blanks. The dried artificial cenosphere blanks are placed in a vortex expansion vitrification furnace for heat treatment. During this process, the modifier transforms into a liquid phase at high temperature and fills the pores of the microspheres. Simultaneously, the gas generated by the high-temperature foaming agent increases the internal pressure of the blank and promotes the formation of a porous structure within the microspheres. Finally, the blanks are cooled in the furnace to obtain artificial cenospheres with a porous internal structure and a dense, hard glaze layer on the surface. This method is simple, low-cost, and suitable for industrial production. The implementation of this method requires the consumption of a large amount of solid waste fly ash, thus reusing the waste. On the one hand, it effectively solves the environmental pollution problem caused by the large accumulation of solid waste fly ash; on the other hand, it manufactures artificial cenospheres, a multifunctional material with huge market demand, at low cost. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the strength test of a single artificial bead in this invention;

[0023] Figure 2 This is a picture of the artificial float beads prepared according to the present invention. Detailed Implementation

[0024] To help those skilled in the art better understand the differences between the present invention and the prior art, the present invention will be further described below with reference to specific embodiments. The content described in the embodiments should not be construed as a limitation of the present invention.

[0025] In the following examples, the artificial cenospheres are all based on a unified preparation method and performance index testing, namely: solid waste fly ash, high-temperature foaming agent, modifier, and binder are weighed according to the raw material ratio, mixed, and dried. Then, the resulting mixture is granulated into artificial cenosphere blanks by a granulator. After drying, the artificial cenosphere blanks are placed in a vortex expansion vitrification furnace or a box-type resistance furnace for heat treatment. Finally, artificial cenospheres with a porous internal structure and a dense and hard glaze layer on the surface are obtained. Among them, the high-temperature foaming agent refers to silicon carbide powder, and the binder refers to carboxymethyl cellulose or dextrin. It should be noted that: experiments have shown that the use of carboxymethyl cellulose or dextrin or a mixture of both as binders has little impact on the performance of the final artificial cenospheres. Therefore, in the examples, only carboxymethyl cellulose is used as an example of binder. The modifier refers to a composite powder of glass powder and perlite powder, wherein the chemical composition of the glass powder is as follows:

[0026] Chemical composition <![CDATA[SiO2]]> <![CDATA[Na2O]]> CaO <![CDATA[Al2O3]]> MgO <![CDATA[K2O]]> <![CDATA[SO2]]> Quality 70.55 10.97 7.72 4.63 3.94 0.54 0.44

[0027] The method for preparing artificial cenospheres using fly ash, a solid waste material, in this invention comprises the following process flow:

[0028] I. Preparation of Artificial Floating Bead Preform

[0029] 1. Weigh solid waste fly ash, high-temperature foaming agent, modifier and binder according to the raw material ratio, put the above raw materials into a ball mill, mix for 45 minutes, and put the mixed raw materials into a drying oven to dry, to obtain a powder mixture with a moisture content of less than 3.0%;

[0030] 2. Add the above powder mixture into the disc granulator. After starting the equipment, control the size and sphericity of the artificial cenosphere blank by controlling the amount of water sprayed, the rotation speed and time of the disc granulator, and obtain the artificial cenosphere blank.

[0031] II. Heat treatment of artificial bead blanks.

[0032] The artificial bead blanks were placed in an electric drying oven and dried at 110℃ for 24 hours. The dried artificial beads were then placed in a vortex expansion vitrification furnace or a box-type resistance furnace for heat treatment. The heat treatment process was as follows: room temperature to 100℃, 2.5℃ / min; 100℃ to 1200℃, 6℃ / min; 1200℃ to 1250℃, 1℃ / min. Finally, the bead was cooled in the furnace, resulting in artificial beads with a porous internal structure and a dense, hard glaze layer on the surface. Figure 2 As shown.

[0033] III. Performance Index Testing.

[0034] The strength test method for a single synthetic bead is attached. Figure 1 As shown, the strength of a single artificial bead was tested using a 500N press. The compressive strength of 10 artificial beads was then measured, and the average value was calculated. The strength of a single artificial bead was obtained using the following formula:

[0035]

[0036] In the formula: S is the compressive strength of a single artificial bead, in MPa; P C X is the load at which the artificial float breaks, in N; X is the diameter of the artificial float, in mm.

[0037] The test method for the water absorption rate of artificial cenospheres is as follows:

[0038] First, weigh 20 artificial cenospheres (m0). Then, place the sample in water and soak for 1 hour, then weigh it again and record the weight as m1. The formula for calculating the water absorption rate of artificial cenospheres is as follows:

[0039] Water absorption rate = (m1 - m0) / m0

[0040] In the formula: m1 is the wet weight of 20 artificial beads, in g; m0 is the dry weight of 20 artificial beads, in g.

[0041] Example 1

[0042] A method for preparing artificial cenospheres using fly ash, a solid waste, is described below by weight: 85 parts fly ash; 10 parts silicon carbide; 15 parts modifier (glass powder and perlite powder mixed in a 1:1 mass ratio); and 3 parts binder.

[0043] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 302 kg / m³. 3 The strength of a single artificial bead is 2.1 MPa; the water absorption rate is 0.8%.

[0044] Example 2

[0045] A method for preparing artificial cenospheres using fly ash, a solid waste material, is described below by weight: 75 parts fly ash, 2 parts silicon carbide, 23 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.2:1), and 1 part binder.

[0046] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 312 kg / m³. 3 The strength of a single artificial bead is 2.4 MPa; the water absorption rate is 0.8%.

[0047] Example 3

[0048] A method for preparing artificial cenospheres using solid waste fly ash, with the following raw material proportions by weight: 74 parts solid waste fly ash; 3 parts silicon carbide; 23 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.2:1); and 1 part binder.

[0049] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 298 kg / m³. 3 The strength of a single artificial bead is 2.0 MPa; the water absorption rate is 0.9%.

[0050] Example 4

[0051] A method for preparing artificial cenospheres using solid waste fly ash, with the following raw material proportions by weight: 72 parts solid waste fly ash; 4 parts silicon carbide; 23 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.2:1); and 1 part binder.

[0052] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 281 kg / m³. 3 The strength of a single artificial bead is 1.6 MPa; the water absorption rate is 1.4%.

[0053] Example 5

[0054] A method for preparing artificial cenospheres using solid waste fly ash, with the following raw material proportions by weight: 72 parts solid waste fly ash; 5 parts silicon carbide; 23 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.5:1); and 1 part binder.

[0055] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 261 kg / m³. 3 The strength of a single artificial bead is 1.2 MPa; the water absorption rate is 1.8%.

[0056] Example 6

[0057] A method for preparing artificial cenospheres using fly ash, a solid waste, is described below by weight: 72 parts fly ash, 1 part silicon carbide, 27 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.2:1), and 2 parts binder.

[0058] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 287 kg / m³. 3 The strength of a single artificial bead is 1.8 MPa; the water absorption rate is 1.1%.

[0059] Example 7

[0060] A method for preparing artificial cenospheres using solid waste fly ash, with the following raw material proportions by weight: 71 parts solid waste fly ash; 6 parts silicon carbide; 23 parts modifier (glass powder and perlite powder mixed at a mass ratio of 1.5:1); and 1 part binder.

[0061] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 237 kg / m³. 3 The strength of a single artificial bead is 1.0 MPa; the water absorption rate is 2.1%.

[0062] Example 8

[0063] A method for preparing artificial cenospheres using fly ash, a solid waste, is described below by weight: 65 parts fly ash; 5 parts silicon carbide; 30 parts modifier (glass powder and perlite powder mixed in a 1:1 mass ratio); and 1 part binder.

[0064] The performance indicators of the artificial cenospheres prepared in this embodiment, as tested, are as follows: bulk density 278 kg / m³. 3 The strength of a single artificial bead is 1.6 MPa; the water absorption rate is 1.2%.

[0065] The comparative sample was a high-quality artificial bead sold on the market.

[0066] The performance of the artificial cling beads prepared in Examples 1-8 of this invention and commercially available high-quality cling beads was compared, and the results are shown in Table 1:

[0067] Table 1. Performance comparison between the artificial flocculants prepared according to this invention and commercially available high-quality flocculants.

[0068]

[0069] As shown in Table 1, the performance of the artificial cenospheres prepared by this invention is comparable to that of commercially available high-quality cenospheres. The compressive strength of a single particle is higher than or close to that of commercially available high-quality cenospheres, and the density and water absorption rate are also within an acceptable range. The artificial cenospheres prepared by this invention can replace commercially available cenospheres and can be widely used in building energy-saving projects such as wall insulation, roof insulation, and composite insulation boards. The market demand is huge, and it can effectively solve the pollution problem caused by the stockpiling of solid waste fly ash.

[0070] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the details described herein.

Claims

1. A method for preparing artificial floating beads by using solid waste fly ash, characterized in that: It comprises the following steps, ​ (1) the solid waste fly ash, high temperature foaming agent, modifier and adhesive are weighed according to the raw material ratio, mixed uniformly, dried, and a mixture with a moisture content of less than 3.0% is obtained; (2) the mixture obtained in step (1) is made into artificial floating bead blank by granulation process; (3) the artificial floating bead blank is placed in an electric drying oven and dried at 110℃ for 24h, and the dried artificial floating bead blank is placed in a spin floating expansion vitrification furnace for heat treatment, in which process the modifier is converted into liquid phase at high temperature and fills the pores of the microbeads; at the same time, the gas generated by the high temperature foaming agent increases the internal pressure of the blank, and the porous structure is formed inside the microbeads, and finally the furnace is cooled to obtain artificial floating beads with porous structure inside and dense and hard glaze layer on the surface; The raw material ratio is 65-85 parts of solid waste fly ash, 2-10 parts of high temperature foaming agent, 15-30 parts of modifier and 1-3 parts of adhesive by weight; The high temperature foaming agent is silicon carbide powder with a particle size of less than 25μm; The modifier is a composite powder of glass powder and perlite powder mixed in a mass ratio of 1-1.5:1, with a particle size of less than 25μm; The adhesive is dextrin and / or carboxymethyl cellulose; In step (3), the artificial floating bead blank is placed in a spin floating expansion vitrification furnace for heat treatment, and the treatment temperature is 1150℃-1250℃; In step (3), when the artificial floating bead blank is placed in a spin floating expansion vitrification furnace for heat treatment, the heating process of heat treatment is as follows: room temperature-100℃, 2.5℃ / min; 100℃-1200℃, 6℃ / min; 1200℃-1250℃, 1℃ / min.

2. The method according to claim 1, wherein the method is characterized in that: The solid waste fly ash refers to the solid waste obtained from the fine ash particles collected after coal combustion in coal-fired power plants, and the particle size of the solid waste is less than 80μm, and the content of silicon dioxide in the solid waste is greater than 38%.

3. The method according to claim 1, wherein the method is characterized in that: In step (2), the granulation process adopts extrusion granulation, stirring granulation or spray drying granulation.

Images