A method for preparing small-diameter ceramsite for sound barrier sound-absorbing material

Abstract

The application discloses a small-particle-size ceramicite preparation method for sound barrier sound-absorbing material, adjusts the iron content, aluminum content and water content of the soil source, and makes the granulator satisfy 0.25<=K1<=0.4 and 0.55<=K2<=0.8, so that the small-particle-size ceramicite is obtained, and an efficient and optimized solution is provided for the preparation of the high-performance sound barrier ceramicite sound-absorbing material.

Description

Technical Field

[0001] This invention belongs to the field of sound-absorbing materials technology, specifically relating to a method for preparing small-diameter ceramic particles for sound-absorbing materials in sound barriers. Technical Background

[0002] In the field of noise control for high-speed railways and urban rail transit, traditional sound barrier sound-absorbing materials mostly use fiber materials such as rock wool, presented in a structure wrapped with water-repellent fabric. However, such materials have many significant drawbacks, such as the difficulty in quality control, and the fact that rock wool and water-repellent fabric are prone to damage, pulverization, and collapse due to production processes or environmental factors, causing the sound barrier to lose its acoustic function. Traditional cement-based sound-absorbing materials also have poor acoustic performance, with low sound absorption coefficients, insufficient sound insulation, and their mechanical strength (compressive and flexural strength) and durability are insufficient to meet long-term use requirements. From an environmental perspective, the production of traditional materials relies on natural resources and fails to effectively address the resource utilization of solid waste such as construction waste and sludge, which contradicts the requirements of green and low-carbon development.

[0003] In contrast, the sintering process of expanded clay aggregate (ECA) has been widely used in the construction industry due to its lightweight, high strength, high sound absorption, high seismic resistance, and high stability. Its stable properties, high sound absorption, lightweight nature, and high pressure resistance make it a promising candidate for use as a sound-absorbing material in high-speed railway sound barriers. However, existing ECA sintering processes have some limitations. On the one hand, the prepared ECA particle size is often large, making it difficult to fully utilize its acoustic function when the thickness of the sound barrier is limited. On the other hand, ECA with different particle sizes and gradations exhibits varying absorption effects on noise at different frequencies, making it difficult to effectively reduce high-speed railway noise, thus limiting the application of ECA in railway sound barriers.

[0004] In summary, how to introduce ceramsite into railway sound barriers, fully utilize its advantages, and solve the problems of large particle size, high density, limited absorption frequency range, and insufficient mechanical properties of existing ceramsite has become a hot research topic. Summary of the Invention

[0005] This invention addresses the problems in the prior art by providing a method for preparing small-particle-size ceramic particles for sound-absorbing materials in sound barriers. This method overcomes the limitation that ceramic particles are difficult to apply to sound barriers and provides a method for preparing small-particle-size ceramic particles for sound-absorbing materials in sound barriers.

[0006] In a first aspect, the present invention provides a method for preparing small-diameter ceramic particles for sound-absorbing materials in sound barriers, comprising the following steps:

[0007] S1: Detect and classify the soil composition, and then adjust the iron content of the classified soil to 5%-8% and the aluminum content to 1%-19%;

[0008] S2: Mix the soil source and adjust the moisture content of the mixed soil source to 20%-30%. Prepare precursor soil bricks with a particle size of 0.4-4.75mm, wherein the sludge mass percentage is less than 30%. Add the precursor soil bricks to a pellet mill to prepare soil pellets. The pellet mill must meet the following requirements: 0.25≤K1≤0.4,

[0009]

[0010] 0.55≤K2≤0.8, where the diameter of the disk is d in meters, and the angle between the disk axis and the vertical direction is θ. The pellet mill rotation speed is V, with units of rad / s, and the feeding speed is Q (m). 3 / h);

[0011] S3: Calcining the clay pellets yields small-diameter ceramsite.

[0012] As a further preferred embodiment, in step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 1.5≤d≤3, 23°≤φ≤38°, 0.3≤v≤0.9, and 5≤Q≤15.

[0013] As a further preferred embodiment, in step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 2≤d<3, 25°≤φ≤35°, 0.4≤v≤0.9, and 8≤Q≤15.

[0014] As a further option, the method for detecting the soil source in step S1 is not limited in principle, including but not limited to any one or more of chemical analysis and spectroscopic analysis methods.

[0015] As a further option, in step S1, the soil source is not limited in principle, and technicians can choose any available soil source, including but not limited to construction waste soil, clay, sludge, shale, and slag, among one or more of these.

[0016] As a further solution, in step S2, the step of adjusting the moisture content of the mixed soil source is as follows: the moisture content of the classified soil sources is adjusted separately, and then the soil sources with different moisture contents are mixed so that the moisture content of the mixed soil source is maintained between 20% and 30%.

[0017] Specifically, in this plan, the moisture content will be adjusted according to different types of soil:

[0018] Among them, the moisture content of the clay was adjusted to 18%-22%;

[0019] The sludge moisture content was adjusted to 28-32%;

[0020] The moisture content of soils other than clay and sludge is adjusted to 3% or less. These other soil types include, but are not limited to, construction waste soil, shale, slag, and one or more other types of soil.

[0021] As a further option, in step S1, the method for adjusting the moisture content of the classified soil is not limited in principle. Technicians can choose different methods to adjust the moisture content of the soil according to their needs. The adjustment methods include, but are not limited to, watering, sun drying, kiln heat recovery drying, and any one or more other methods.

[0022] As a further option, in step S1, the method for adjusting the iron / aluminum content of the classified soil source is to add iron / aluminum compounds or soil with low iron / aluminum content corresponding to the classified soil type to the classified soil source.

[0023] As some preferred examples, the iron content of the soil after classification was adjusted to 5%-8%, and the aluminum content to 10%-18%.

[0024] As a further option, the iron / aluminum compound refers to any one or more of iron / aluminum oxides and iron / aluminates.

[0025] As a further option, in step S2, before preparing the soil pellets by the pellet mill, the step of preparing the precursor soil pellets is as follows: preparation is carried out according to different soil sources. When the soil source contains only clay, the clay is crushed, then extruded into pellets, and particles with a particle size of 0.4-4.75mm are screened out to obtain the precursor soil pellets.

[0026] When the soil source contains other types of soil, the clay is crushed, then mixed with other types of soil, extruded into granules, and sieved to obtain particles with a particle size of 0.4-4.75 mm to obtain precursor soil.

[0027] Particles that do not meet the requirements after screening are re-extruded into granules and then screened again.

[0028] As a further option, the method of crushing clay is not limited in principle. Technicians can choose the appropriate method to crush it, such as using a vertical soil granulator to crush the clay.

[0029] As a further option, the method of extruding the mixed soil into granules is not limited in principle; technicians can choose different methods and extrusion equipment to prepare granules according to their needs.

[0030] As a further embodiment, the sludge mass percentage in the precursor adobe is less than or equal to 25%.

[0031] As a further option, the calcination temperature in step S3 is selected from 950℃-1300℃, and the calcination time is greater than 60min.

[0032] As some preferred examples, the calcination temperature in step S3 is selected from 1000℃-1200℃, and the calcination time is selected from 80-180min.

[0033] Secondly, this solution provides a method for preparing small-particle-size ceramsite using the above-mentioned method, where the particle size is 0.6–5 mm and the bulk density is less than or equal to 600 g / m³. 3 .

[0034] Thirdly, the present invention provides a small-diameter ceramic particle sound baffle, comprising small-diameter ceramic particles.

[0035] As a further embodiment, the sound-absorbing plate prepared from the small-diameter ceramsite sound baffle has a thickness greater than 45mm.

[0036] As a further solution, the sound absorption coefficient of small-diameter ceramic abrasive baffles is greater than 0.3 for noise at 125Hz and greater than 0.6 for noise at 125Hz.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] This solution achieves precise particle size control and significant improvement in sound absorption performance of lightweight, small-diameter ceramsite by precisely controlling the iron, aluminum, and moisture content of the soil source and optimizing the pelletizing process parameters. Specifically, controlling the iron content of the soil source to 5%–8% and the aluminum content to 1%–19% enhances the bonding force and compressive strength of the adobe particles, avoiding particle breakage and adhesion problems, while optimizing the bulk density and overall performance of the ceramsite. Regulating the moisture content of the soil source to 20%–30% effectively prevents crushing and sticking during the pelletizing process, ensuring the quality and particle size stability of the ceramsite after calcination. Furthermore, through multi-parameter coupling optimization (K1≤0.4, 0.55≤K2≤0.8), synergistic optimization of the pelletizing process parameters and soil properties is achieved, resulting in ceramsite with good particle size distribution and excellent sound absorption performance, with noise absorption coefficients greater than 0.3 and 0.6 in the 125Hz and 250Hz frequency bands, respectively. Ultimately, this solution significantly broadens the application scope of ceramsite in sound baffles, solves the problems of difficult particle size control and limited sound absorption performance in traditional preparation methods, and provides an efficient and optimized solution for the development of high-performance ceramsite sound baffles, with broad application prospects. Detailed Implementation

[0039] For ease of understanding, the present invention will be described more fully below, and embodiments of the present invention will be given, but this does not limit the scope of the present invention.

[0040] The following are descriptions of terms or words, and unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] Unless otherwise specified, the moisture content, iron content, and aluminum content mentioned in this invention refer to mass content.

[0042] This invention provides a method for preparing small-particle-size ceramsite for sound-absorbing materials in sound barriers, comprising the following steps:

[0043] S1: Detect and classify the soil composition, and then adjust the iron content of the classified soil to 5%-8% and the aluminum content to 1%-19%;

[0044] S2: Mix the soil source and adjust the moisture content of the mixed soil source to 20%-30%. Make the soil source into precursor soil bricks with a particle size of 0.4-4.75mm, in which the sludge mass ratio is less than 30%. Add the precursor soil bricks to a pellet mill to prepare soil brick particles.

[0045] Among them, the pellet mill meets the requirements

[0046] 0.25≤K1≤0.4,

[0047]

[0048] 0.55≤K2≤0.8, where the diameter of the disk is d in meters, and the angle between the disk axis and the vertical direction is θ. The pellet mill rotation speed is V, with units of rad / s, and the feeding speed is Q (m). 3 / h);

[0049] S3: Calcining the clay pellets yields small-diameter ceramsite.

[0050] The frequency range of sound absorption by ceramsite is closely related to its particle size. Controlling the particle size of ceramsite helps to increase the density of ceramsite when preparing sound baffles, thereby enhancing its sound absorption capacity. Furthermore, it helps to optimize the sound absorption range of ceramsite and broaden its application in sound baffles. However, controlling the particle size of ceramsite during the firing process is not easy. During firing, the particle size is often affected by various factors such as soil moisture content, metal content in the soil, granulation speed, feeding speed, granulator diameter, and even calcination conditions. This solution achieves control over the iron and aluminum content in the classified soil. Since iron in the soil can act as a natural binder, it enhances the cohesion and compressive strength of the adobe particles. Synergistic aluminum content improves soil swelling and shear capacity. By controlling the iron content of the sorted soil (5%–8%) and aluminum content (1%–19%), the iron and aluminum content in the soil source are controlled. This effectively optimizes the binding force between soil particles, preventing particle breakage due to mechanical stress (such as friction from the pellet mill disc and centrifugal force) and avoiding adhesion inside the pellet mill. This, combined with pellet mill parameters, effectively controls the size of small-diameter ceramsite. Furthermore, controlling the iron and aluminum content helps optimize the bulk density of small-diameter ceramsite, further improving its overall performance. Simultaneously, this method also regulates the moisture content of the mixed soil source. The combined soil source has a moisture content of 20%-30%. This scheme helps to avoid the crushing or sticking of the prepared precursor adobe in the pellet mill, and at the same time, it controls the particle size of small-diameter ceramsite by adjusting the pellet mill parameters. It also prevents clumping during calcination or affecting the weight of small-diameter ceramsite, thus impacting its quality. After adjusting the soil source moisture content, iron content, and aluminum content, this scheme comprehensively considers various parameters for preparing adobe pellets, including the disc diameter, the angle between the disc axis and the vertical direction, the pellet mill speed, and the feeding speed. In numerous experiments, researchers found that the disc diameter affects material distribution; the angle between the disc axis and the vertical direction affects the material trajectory; and the pellet mill speed represents centrifugal force. The relationship with gravity and the regulation of their balance are considered. The feeding speed affects the nucleation density of the precursor soil. In formulas K1 and K2, this scheme comprehensively considers the interaction of the above factors. Through multi-parameter coupling constraints, the synergistic optimization of the pellet mill process parameters and soil source properties (such as iron content, aluminum content, and moisture content) is achieved. When 0.25≤K1≤0.4 and 0.55≤K2≤0.8, the small-diameter ceramsite prepared by this scheme has good particle size distribution and good absorption capacity for noise in different frequency bands such as 125Hz and 250Hz (when used for sound baffles with a thickness greater than 45mm, the sound absorption coefficient for 125Hz noise is greater than 0.3 and the sound absorption coefficient for 125Hz noise is greater than 0.6).

[0051] As some preferred examples, in step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 1.5≤d≤3, 23°≤φ≤38°, 0.3≤v≤0.9, and 5≤Q≤15.

[0052] As some preferred examples, in step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 2≤d<3, 25°≤φ≤35°, 0.4≤v≤0.9, and 8≤Q≤15.

[0053] As some examples, the method for detecting the soil source in step S1 is not limited in principle, including but not limited to any one or more of chemical analysis and spectroscopic analysis methods.

[0054] As examples, the chemical analysis method is selected from any one or more of the potentiometric method, potassium dichromate oxidation method, and heavy metal detection method.

[0055] As examples, the spectroscopic analysis method is selected from any one or more of near-infrared spectroscopy and X-ray fluorescence spectroscopy.

[0056] As an example, in step S1, the soil source is not limited in principle. Technicians may choose any available soil source, including but not limited to construction waste soil, clay, sludge, shale, and slag.

[0057] As an example, in step S2, the step of adjusting the moisture content of the mixed soil source is as follows: the moisture content of the classified soil source is adjusted separately, and then the soil sources with different moisture contents are mixed so that the moisture content of the mixed soil source is maintained between 20% and 30%.

[0058] Specifically, in this plan, the moisture content will be adjusted according to different types of soil:

[0059] Among them, the moisture content of the clay was adjusted to 18%-22%;

[0060] The sludge moisture content was adjusted to 28-32%;

[0061] The moisture content of soils other than clay and sludge is adjusted to 3% or less. These other soil types include, but are not limited to, construction waste soil, shale, slag, and one or more other types of soil.

[0062] As examples, in step S1, the method for adjusting the moisture content of the classified soil is not limited in principle. Technicians can choose different methods to adjust the moisture content of the soil according to their needs. The adjustment methods include, but are not limited to, watering, sun drying, kiln heat recovery drying, and any one or more other methods.

[0063] As some examples, in step S1, the method of adjusting the iron / aluminum content of the classified soil source is to add iron / aluminum compounds or soil with low iron / aluminum content corresponding to the classified soil type to the classified soil source. Here, the soil source with low iron content refers to soil source with iron content of less than 5%, and the soil source with low aluminum content refers to soil source with aluminum content of less than 15%.

[0064] As some preferred examples, the iron content of the soil after adjustment and classification is 5% to 8%, and the aluminum content is 1% to 19%.

[0065] As examples, the iron / aluminum compounds refer to any one or more of iron / aluminum oxides and iron / aluminates.

[0066] As examples, the iron and aluminum oxides refer to oxides containing only iron, aluminum and oxygen elements in different valence states, including any one or more of ferrous oxide, ferric oxide, iron(II) oxide, ferric oxide, ferric oxide, and aluminum oxide.

[0067] As examples, the ferrates and aluminates refer to oxides containing iron and other metals, including any one or more of calcium ferrate, sodium ferrate, potassium ferrate, lithium ferrate, magnesium ferrate, aluminum ferrate, zinc ferrate, barium ferrate, manganese ferrate, copper ferrate, and magnesium aluminate.

[0068] As some examples, in step S2, before preparing the precursor soil cells by the granulator, the preparation of the precursor soil cells is as follows: the preparation is carried out according to different soil sources. When the soil source contains only clay, the clay is crushed, then extruded into granules, and particles with a particle size of 0.4-4.75mm are screened out to obtain the precursor soil cells.

[0069] When the soil source contains other types of soil, the clay is crushed, then mixed with other types of soil, extruded into granules, and sieved to obtain particles with a particle size of 0.4-4.75 mm to obtain precursor soil.

[0070] Particles that do not meet the requirements after screening are re-extruded into granules and then screened again.

[0071] In some cases, the method of crushing clay is not limited in principle. Technicians can choose the appropriate method to crush it, such as using a vertical soil granulator to crush the clay.

[0072] As some examples, there are no restrictions on the method of extruding the mixed soil into granules. Technicians can choose different methods and extrusion equipment to prepare granules according to their needs.

[0073] As some examples, the sludge mass ratio in the precursor adobe is less than or equal to 25%, which helps to control the proportion of organic matter by controlling the sludge, thereby optimizing the internal pores of small-diameter ceramsite and improving the sound absorption performance and compressive strength of small-diameter ceramsite.

[0074] As examples, the calcination temperature in step S3 is selected from 950℃-1300℃, and the calcination time is greater than 60min.

[0075] As some preferred examples, the calcination temperature in step S3 is selected from 1000℃-1200℃, and the calcination time is selected from 80-180min, which helps to further improve the pore uniformity of small-diameter ceramsite, thereby improving the sound absorption performance of small-diameter ceramsite.

[0076] Secondly, this solution provides a method for preparing small-particle-size ceramsite using the above-mentioned method, where the particle size is 0.6–5 mm and the bulk density is less than or equal to 600 g / m³. 3 .

[0077] Thirdly, the present invention provides a small-diameter ceramic particle sound baffle, comprising small-diameter ceramic particles.

[0078] As a further embodiment, the sound-absorbing plate prepared from the small-diameter ceramsite sound baffle has a thickness greater than 45mm.

[0079] As a further solution, the sound absorption coefficient of small-diameter ceramic abrasive baffles is greater than 0.3 for noise at 125Hz and greater than 0.6 for noise at 125Hz.

[0080] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application and do not represent all possible embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0081] The chemical raw materials used in the following examples and comparative examples are all prior art and were obtained commercially. The experimental apparatus and testing equipment used in the following examples and comparative examples are all conventional equipment in the art, and there are no special requirements or limitations.

[0082] Example 1

[0083] S1: By testing the soil composition, the soil is divided into clay, sludge, shale, and slag. The clay, sludge, shale, and slag are then dried to achieve a moisture content of 20% for the clay, 30% for the sludge, and 2% for the shale and slag. Ferric oxide, aluminum oxide, or their compounds are added to the clay, sludge, shale, and slag respectively and mixed evenly to achieve an iron content of approximately 6% and an aluminum content of approximately 14% in the clay, sludge, shale, and slag.

[0084] S4: Clay is crushed using a vertical soil granulator and then mixed with sludge, shale, and slag. Sludge comprises 20% of the total mixed soil mass, and the mixed soil moisture content is 25%. Particles are prepared using a roller granulator and then sieved through a 4.75mm mesh screen to obtain precursor soil blocks with a particle size of 0.4-4.75mm. The precursor soil blocks are then fed into a disc granulator for pelletizing. The disc diameter is 2.5m, the angle between the disc axis and the vertical direction is 30°, the granulator speed is 0.628 rad / s, and the feeding speed is 10m / s. 3 / h;

[0085] S5: The soil pellets granulated by the disc granulator are fed into a rotary kiln and calcined at 1100℃ for 60 minutes to obtain small-diameter ceramsite.

[0086] Example 2

[0087] The synthesis method and preparation steps are the same as in Example 1, except that the diameter of the disk is 2m.

[0088] Example 3

[0089] The synthesis method and preparation steps are the same as in Example 1, except that the diameter of the disk is 3m.

[0090] Example 4

[0091] The synthesis method and preparation steps are the same as in Example 1, except that the angle between the disk axis and the vertical direction is 23°.

[0092] Example 5

[0093] The synthesis method and preparation steps are the same as in Example 1, except that the angle between the disk axis and the vertical direction is 38°.

[0094] Example 6

[0095] The synthesis method and preparation steps are the same as in Example 1, except that the granulator speed is 0.3 rad / s.

[0096] Example 7

[0097] The synthesis method and preparation steps are the same as in Example 1, except that the granulator speed is 0.9 rad / s.

[0098] Example 8

[0099] The synthesis method and preparation steps are the same as in Example 1, except that the feeding speed is 5m. 3 / h.

[0100] Example 9

[0101] The synthesis method and preparation steps are the same as in Example 1, except that the feeding speed is 15m. 3 / h.

[0102] Example 10

[0103] The synthesis method and preparation steps are the same as in Example 1, except that the sludge mass ratio is 30%.

[0104] Example 11

[0105] The synthesis method and preparation steps are the same as in Example 1, except that the calcination temperature is 1000℃ and the calcination time is 40min.

[0106] Comparative Example 1

[0107] The synthesis method and preparation steps are the same as in Example 1, except that the moisture content of the clay is 70% and the moisture content of the mixed soil is 45%.

[0108] Comparative Example 2

[0109] The synthesis method and preparation steps are the same as in Example 1, except that the moisture content of the silt is 50% and the moisture content of the mixed soil is 47%.

[0110] Comparative Example 3

[0111] The synthesis method and preparation steps are the same as in Example 1, except that the iron content is 1% and the aluminum content is 10%.

[0112] Comparative Example 4

[0113] The synthesis method and preparation steps are the same as in Example 1, except that the iron content is 15% and the aluminum content is 25%.

[0114] Comparative Example 5

[0115] The synthesis method and preparation steps are the same as in Example 1, except that the precursor soil particle size is 5-10 mm.

[0116] Comparative Example 6

[0117] The synthesis method and preparation steps are the same as in Example 1, except that the mass ratio of silt in the precursor soil particles is 50%.

[0118] Comparative Example 7

[0119] The synthesis method and preparation steps are the same as in Example 1, except that the diameter of the disk is 2.5m, the angle between the disk axis and the vertical direction is 23°, the granulator speed is 0.4rad / s, and the feeding speed is 6m / s. 3 / h, K1 is 0.23, K2 is 0.78.

[0120] Comparative Example 8

[0121] The synthesis method and preparation steps are the same as in Example 1, except that the diameter of the disk is 2.5m, the angle between the disk axis and the vertical direction is 23°, the granulator speed is 0.4rad / s, and the feeding speed is 6m / s. 3 / h, K1 is 0.19, K2 is 0.85.

[0122] Test methods

[0123] Expanded clay aggregate was mixed with water, cement, and latex powder in a ratio of 6:1:0.15 to prepare a 50mm thick expanded clay aggregate sound-absorbing board, which was installed in the expanded clay aggregate metal sound barrier structure. The thickness of the air layer behind it was 54.5mm. The sound absorption coefficients at 125Hz and 250Hz were measured according to the standard "Acoustic Reverberation Chamber Sound Absorption Measurement" (GB / T20247-2006).

[0124] The test results are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128]

[0129] As can be observed from Examples 1-11 and Comparative Examples 1-8, Examples 1-11 exhibit superior overall sound absorption capabilities at 125Hz and 250Hz compared to Comparative Examples 1-8. This indicates that the preparation method proposed in this scheme can effectively absorb sound waves of different frequency bands in railway noise, thereby broadening the application of ceramsite in railway sound barriers.

[0130] First, based on Example 1 and Comparative Examples 1-4, it can be observed that when the moisture content or iron / aluminum content in the comparative examples does not meet the requirements of a mixed soil moisture content of 20%-30% (clay moisture content of 18-22%, sludge moisture content of 28-32%, and remaining soil moisture content of less than 2%), a soil iron content of 5%-8%, and an aluminum content of 1%-19%, Comparative Examples 1-4 exhibit a comprehensive sound absorption capacity far lower than that of Example 1. This may be because when the moisture content of any soil in the soil source is higher than the set moisture content (clay moisture content of 18-22%, sludge moisture content of 28-32%, and remaining soil moisture content of less than 4-2%) (Comparative Examples 1 and 2), it is impossible to successfully prepare small-diameter ceramsite with the granulator, and it is also impossible to control the particle size of small-diameter ceramsite. Therefore, the average particle size of Comparative Examples 1 and 2 is significantly worse than that of Example 1, and their sound absorption capacity is also inferior to that of Example 1. Meanwhile, Comparative Example 3-4, which does not meet the iron / aluminum ratio requirement, may affect the soil's cohesiveness and particle mechanical properties, thereby affecting the performance of small-diameter ceramsite. Therefore, Comparative Example 3-4 exhibits weaker sound absorption performance and worse bulk density.

[0131] In Example 1 and Comparative Example 5, it can be observed that when the precursor soil particle size is 5-10mm, the average particle size of Comparative Example 5 is significantly affected, and its sound absorption capacity is also significantly weaker than that of Example 1. This may be because the 0.4-4.75mm precursor soil, as the basis of the soil particles, can better respond to the process parameters of the pelletizer in the subsequent pelletizing process, thereby achieving precise control of the particle size of small-diameter ceramsite. When the precursor soil particle size is 5-10mm, the conditions of the pelletizer will not be able to effectively control the precursor soil, thus affecting the performance of Comparative Example 5.

[0132] Sludge typically contains a large amount of organic matter. When the content exceeds 30%, a large amount of gas will be released during calcination, which will affect the pores and surface glaze of small-diameter ceramsite. Therefore, it is necessary to control the mass ratio of sludge. As can be observed from Example 1 and Comparative Example 6, when the mass ratio of sludge is 50%, the average particle size and overall sound absorption capacity of Comparative Example 6 are significantly affected. Therefore, the mass ratio of sludge in the raw materials for preparing small-diameter ceramsite should be controlled to be less than 30%.

[0133] Based on the above conditions, as observed in Examples 1 and 7-8, even if the moisture content, iron content, aluminum content, silt mass ratio, and precursor adobe particle size in the soil source all meet the requirements, Comparative Example 7-8 still cannot obtain ideal small-diameter ceramsite when the conditions of either formula K1 or K2 are not met. This is because the parameters affecting the particle size of small-diameter ceramsite are very complex, and only when the above conditions work together can the ideal result be obtained. In Comparative Example 7-8, K1 and K2 cannot be met, therefore Comparative Example 7-8 cannot simultaneously achieve absorption at 125Hz and 250Hz.

[0134] In Examples 1-9, this scheme further optimizes the parameters in K1 and K2. It can be observed that in Examples 1-3, as the diameter of the disc gradually increases, the sound absorption coefficient of small-diameter ceramsite at 250Hz gradually increases. In Examples 1, 4, and 5, the increase of the angle φ between the disc axis and the vertical direction is accompanied by the increase of the sound absorption coefficient at 125Hz. The increase of the pellet mill speed is also accompanied by the enhancement of the sound absorption capacity at 125Hz (Examples 1, 6, and 7). The increase of the feeding speed Q can also bring about the optimization of the sound absorption capacity at 125Hz (Examples 1, 8, and 9). After comprehensively considering the sound absorption performance of small-diameter ceramsite at 125Hz and 250Hz, based on Examples 1-9, the preferred pellet mill of this scheme satisfies: 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 2≤d<3, 25°≤φ≤35°, 0.4≤v≤0.9, and 8≤Q≤15.

[0135] In Example 10, this scheme further optimizes the mass ratio of sludge in the precursor adobe. As can be observed from Examples 1 and 10, Example 1 exhibits better sound absorption capacity than Example 10. This may be because when the mass ratio of sludge in the precursor adobe is less than 25%, it helps to further optimize the internal pore structure of small-diameter ceramsite and improve the sound absorption performance of small-diameter ceramsite.

[0136] Examples 1 and 11 discuss the effect of calcination temperature on the performance of small-diameter ceramsite. When the calcination temperature is selected from 1000℃-1200℃ and the calcination time is selected from 80-180min, Example 1 shows better sound absorption performance than Example 11.

[0137] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A method for preparing small-particle-size ceramsite for sound-absorbing materials in sound barriers, characterized in that, Includes the following steps: S1: Detect and classify the soil composition, and then adjust the iron content of the classified soil to 5%-8% and the aluminum content of the soil to 1%-19%; S2: Mix the soil source and adjust the moisture content of the mixed soil source to 20%-30%. Prepare precursor soil bricks with a particle size of 0.4-4.75mm, wherein the sludge mass percentage is less than 30%. Add the precursor soil bricks to a pelletizer to prepare soil pellets. The pelletizer must meet the following requirements: , Wherein, the diameter of the disc is d (in meters), the angle between the disc axis and the vertical direction is θ (in degrees), the pellet mill speed is V (in rad / s), and the feeding speed is Q (in meters). 3 / h; S3: Calcining the clay pellets yields small-diameter ceramsite.

2. The preparation method according to claim 1, characterized in that, In step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 1.5≤d≤3, 23°≤φ≤38°, 0.3≤V≤0.9, and 5≤Q≤15.

3. The preparation method according to claim 1, characterized in that, In step S3, the granulator satisfies 0.3≤K1≤0.4, 0.6≤K2≤0.8, where 2≤d<3, 25°≤φ≤35°, 0.4≤V≤0.9, and 8≤Q≤15.

4. The preparation method according to claim 1, characterized in that, The method for detecting the soil source in step S1 is selected from any one or more of chemical analysis methods and spectroscopic analysis methods. In step S1, the soil source is selected from any one or more of construction waste soil, clay, sludge, shale, and slag.

5. The preparation method according to claim 1, characterized in that, In step S2, the step of adjusting the moisture content of the mixed soil source is as follows: the moisture content of the classified soil source is adjusted separately, and then the soil sources with different moisture contents are mixed so that the moisture content of the mixed soil source is maintained between 20% and 30%.

6. The preparation method according to claim 5, characterized in that, Adjust the moisture content according to different types of soil: The moisture content of the clay should be adjusted to 18%-22%; The sludge moisture content was adjusted to 28-32%; Except for clay and sludge, the moisture content of other types of soil is adjusted to 3% or below. The other types of soil include, but are not limited to, construction waste soil, shale, slag and other one or more types of soil. In step S2, the method for adjusting the moisture content of the classified soil source is selected from any one or more methods such as watering, sun drying, and kiln heat recovery drying.

7. The preparation method according to claim 1, characterized in that, In step S1, the method for adjusting the iron / aluminum content of the classified soil source is to add iron / aluminum compounds or soil with low iron / aluminum content corresponding to the classified soil type to the classified soil source.

8. The preparation method according to claim 1, characterized in that, The iron content of the soil after classification is adjusted to 5%-8%, and the aluminum content to 10%-18%.

9. The preparation method according to claim 7, characterized in that, The iron / aluminum compound refers to any one or more of iron / aluminum oxides and iron / aluminates.

10. The preparation method according to claim 1, characterized in that, In step S2, before preparing the soil pellets by the pellet mill, the step of preparing the precursor soil pellets is as follows: preparation is carried out according to different soil sources. When the soil source contains only clay, the clay is crushed, then extruded into pellets, and particles with a particle size of 0.4-4.75mm are screened out to obtain the precursor soil pellets. When the soil source contains other types of soil, the clay is crushed, then mixed with other types of soil, extruded into granules, and sieved to obtain particles with a particle size of 0.4-4.75 mm to obtain precursor soil. Particles that do not meet the requirements after screening are re-extruded into granules and then screened again.

11. The preparation method according to claim 10, characterized in that, The method for crushing clay is to use a vertical soil granulator to break up the clay.

12. The preparation method according to claim 10, characterized in that, The sludge mass percentage of the precursor adobe is less than or equal to 25%.

13. The preparation method according to claim 1, characterized in that, In step S3, the calcination temperature is selected from 950℃-1300℃, and the calcination time is greater than 30min.

14. The preparation method according to claim 1, characterized in that, In step S3, the calcination temperature is selected from 1000℃-1200℃, and the calcination time is selected from 50-100min.

15. A type of small-diameter ceramsite, characterized in that, Prepared by any one of the methods of claims 1-14.

16. The small-diameter ceramsite according to claim 15, characterized in that, Small-diameter ceramsite has a particle size of 0.6~5mm and a bulk density of less than or equal to 600g / m³. 3 .

17. A small-particle-size ceramsite sound baffle, characterized in that, Includes the small-diameter ceramic particles as described in claim 15.

18. The small-particle-size ceramsite sound baffle according to claim 17, characterized in that, The sound-absorbing plate prepared from the small-diameter ceramsite sound baffle has a thickness greater than 45mm. Small-diameter ceramsite sound baffles have a noise absorption coefficient greater than 0.3 at 125Hz and a noise absorption coefficient greater than 0.6 at 250Hz.

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