A method for preparing ceramsite by co-processing multiple solid wastes and its application

Abstract

The present invention relates to the technical field of solid waste resource utilization, and in particular to a method for preparing ceramsite by co-processing multiple solid wastes. The method comprises the following steps: S1, uniformly stirring and mixing water plant sludge, non-washed waste incineration fly ash, contaminated soil and iron tailings slag powder in proportion to obtain a stirred mixture; S2, directly placing the uniformly mixed wet stirred mixture into a ceramsite drying and granulation kiln, and granulating the mixture in the kiln to obtain raw material balls; S3, passing the raw material balls into a pyrolysis section in the kiln for low-temperature pyrolysis treatment; S4, passing the pyrolyzed raw material balls into a calcining kiln for high-temperature sintering treatment; S5, passing the obtained sample through a cooling kiln, and taking out the cooled sample to obtain the multiple solid waste ceramsite. The present invention uses pure solid waste to prepare ceramsite, eliminating the steps of drying and granulating raw materials in traditional ceramsite manufacturing. Water plant sludge, waste incineration fly ash, contaminated soil and iron tailings slag are utilized in a high-value manner, with low energy consumption and less secondary environmental pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and in particular to a method for preparing ceramsite by co-disposal of multiple solid wastes. Background Art

[0002] With China's sustainable development and accelerated urbanization, the number of municipal solid waste incineration plants and sewage treatment plants has gradually increased. With China's sustainable development and transition to a green economy, an increasing number of metal smelters and mines are facing closure and relocation. The relocation and closure of factories and mines generates large amounts of solid waste, such as tailings, waste rock, fly ash, and industrial waste. The surface soil of relocated or closed smelters and mines is covered by various solid wastes for a long time, and coupled with rainwater erosion, a large amount of heavy metals accumulate in the soil. These accumulated heavy metals are difficult to remove through dilution and self-purification within the ecological environment.

[0003] Previous reports have shown that solid wastes such as contaminated soil, waterworks sludge, and various metal slags can be used as raw materials or catalysts for the production of ceramsite. In recent years, a growing number of researchers have begun researching the production of ceramsite from solid wastes. However, these studies primarily focus on single solid wastes, using clay or shale as the primary raw material for ceramsite production. Producing high-temperature sintered ceramsite using these raw materials not only fails to effectively treat solid waste but also consumes significant land resources. The production of ceramsite from single solid wastes typically uses a single industrial solid waste as the primary raw material, such as fly ash, coal gangue, or sewage sludge. This type of ceramsite fully utilizes the chemical composition and physical properties of a single solid waste, offering a single raw material source and relatively stable composition. However, this method is relatively limited in terms of solid waste treatment capacity, primarily due to the supply and processing capacity of the single solid waste. The synergistic production of ceramsite from multiple solid wastes involves combining two or more industrial solid wastes in a specific ratio, such as fly ash and coal gangue, or steel slag and sewage sludge. This approach not only allows for greater solid waste disposal, but also optimizes the performance of ceramsite by leveraging the complementary strengths of different solid wastes. In terms of solid waste treatment capacity, the collaborative preparation of multiple solid wastes offers significant advantages, enabling the simultaneous treatment of multiple types of solid waste, significantly increasing the total solid waste treatment capacity.

[0004] The process of preparing ceramsite from a single solid waste is relatively simple, mainly including the steps of crushing, mixing, pelletizing, drying, sintering and cooling. Due to the single raw material composition, process parameters such as sintering temperature and time are relatively fixed, and product performance is relatively consistent. However, this process may face bottlenecks in equipment capacity and efficiency when treating large-scale solid waste. The process of synergistically preparing ceramsite from multiple solid wastes is more complicated, requiring pretreatment of different solid wastes and optimization of the ratio according to their chemical composition and physical properties. During the sintering process, the control of temperature and time is also more stringent to ensure that the chemical reactions and physical changes between different solid wastes can be coordinated to obtain the ideal ceramsite product. Despite the complexity of the process, the synergistic preparation of ceramsite from multiple solid wastes is more flexible in processing capacity and can adapt to the treatment needs of different types and quantities of solid waste.

[0005] The performance of ceramsite prepared from a single solid waste as raw material mainly depends on the characteristics of the solid waste itself. For example, fly ash ceramsite usually has good thermal insulation properties, while coal gangue ceramsite has higher strength and wear resistance. However, due to the single raw material, this type of ceramsite has limited room for improvement in performance and it is difficult to meet multiple performance requirements at the same time, which also limits its further expansion in solid waste treatment capacity. Ceramsite prepared from multiple solid wastes can often have the advantages of each single solid waste ceramsite due to the interaction of multiple solid waste components, and achieve breakthroughs in certain performance. The specific performance differences can be reflected in the following indicators:

[0006] 1. Strength and durability: Through reasonable proportions and process control, multi-solid waste ceramsite can significantly improve strength and durability while maintaining a low density. However, single solid waste ceramsite may have limited performance in this regard.

[0007] 2. Thermal insulation performance: Although some single solid wastes, such as fly ash ceramsite, have good thermal insulation performance, multi-solid waste ceramsite may achieve better performance in thermal insulation through the synergistic effect of multiple materials;

[0008] 3. Wear resistance and fire resistance: Single solid waste ceramsite such as coal gangue ceramsite has high strength and wear resistance, but multi-solid waste ceramsite may achieve more balanced development in wear resistance and fire resistance through the complementary advantages of different materials.

[0009] The application areas of single solid waste ceramsite are relatively fixed, mainly based on its performance characteristics. For example, fly ash ceramsite is often used in building insulation materials, and sludge ceramsite is mostly used as filter media in sewage treatment. Although these application areas are stable, it is difficult to achieve large-scale breakthroughs in solid waste treatment volume. Ceramsite prepared from multiple solid wastes has a wider range of applications due to its excellent comprehensive performance. For example, high-strength ceramsite can be used in load-bearing structures, ultra-light ceramsite can be used for roof and wall insulation, and ceramsite for water treatment can be used as high-efficiency filter media for sewage treatment and reuse. The wide application of multiple solid waste ceramsite gives it greater potential in solid waste treatment volume, which can meet the demand for ceramsite in different industries, thereby further increasing the amount of solid waste treatment.

[0010] From an environmental and economic perspective, whether using a single solid waste or multiple solid wastes to produce ceramsite, it can effectively dispose of industrial solid waste, reduce environmental pollution, and have significant environmental benefits. However, the synergistic production of ceramsite from multiple solid wastes offers even greater advantages in comprehensive resource utilization. The coordinated utilization of multiple solid wastes not only increases solid waste utilization but also addresses the difficulty of using certain solid wastes individually, further enhancing economic and social benefits.

[0011] However, traditional off-kiln granulation for ceramsite production requires pre-processing of the raw materials outside the rotary kiln, including crushing, grinding, and pelletizing. The pellets are then fed into the kiln for expansion and cooling, resulting in a complex process. If a variety of solid wastes are used as raw materials for ceramsite production, traditional off-kiln granulation requires pre-processing of each type of solid waste, requiring additional pre-processing equipment, which in turn increases equipment costs, labor costs, and energy consumption.

[0012] In summary, there are significant differences between the preparation of ceramsite using a single solid waste as raw material and the synergistic preparation of ceramsite using multiple solid wastes in terms of raw material selection, preparation process, product performance, and application areas, particularly in terms of solid waste treatment capacity. The synergistic preparation of ceramsite using multiple solid wastes demonstrates greater potential for comprehensive resource utilization and product performance optimization, and represents an important direction for the future development of ceramsite preparation technology. Therefore, the rational use of pure multiple solid wastes to synergistically process high-strength, porous, green ceramsite for application in the field of solid waste resource utilization technology has significant practical significance for achieving resource utilization of solid waste and removing heavy metal pollutants from soil. Summary of the Invention

[0013] The purpose of the present invention is to address the problems existing in the background technology and propose a method for preparing ceramsite by co-disposal of multiple solid wastes, a method for preparing ceramsite by utilizing fly ash from garbage incineration, sludge from waterworks, contaminated soil and iron tailings, and a new type of ceramsite drying and granulation kiln to realize ceramsite kiln granulation to solve the problem of drying ceramsite raw materials and save the cost of ceramsite granulation outside the kiln.

[0014] The technical solution of the present invention, in a first aspect, provides a method for preparing ceramsite by co-processing multiple solid wastes, comprising the following specific steps:

[0015] S1. Mixing and stirring raw materials: water plant sludge, disposable waste incineration fly ash, contaminated soil and iron tailings slag powder are uniformly mixed in proportion to obtain a stirred mixture;

[0016] S2, granulation molding: the uniformly mixed wet state stirred mixture obtained in step S1 is directly placed into a ceramsite drying and granulation kiln, and granulated in the kiln to obtain raw material balls;

[0017] S3, low-temperature pyrolysis: the raw material balls obtained in step S2 enter the pyrolysis section in the kiln for low-temperature pyrolysis treatment;

[0018] S4, high temperature sintering: the pyrolyzed raw material balls obtained in step S3 are put into a calcining kiln for high temperature sintering;

[0019] S5. Cooling: The sample obtained in step S4 is passed through a cooling kiln, and the multi-component solid waste ceramsite obtained by cooling the sample is taken out.

[0020] Preferably, the raw material ratio in step S1 is 15% of water plant sludge, 12% of iron ore tailings, 15% of waste incineration fly ash and 58% of contaminated soil, and the fly ash uses unwashed raw ash.

[0021] Preferably, in step S1, the raw materials are crushed into coarse particles, which are then pulverized using a crusher and sieved through a nylon sieve to obtain a powdered sample.

[0022] Preferably, the moisture content of the wet mixture in step S2 is controlled at 70%-80%, the temperature of the ceramsite drying and granulation kiln is 120-160°C, the drying time is 5-10 minutes, and the diameter of the prepared raw material balls is 1-2 cm.

[0023] Preferably, the low-temperature pyrolysis temperature in step S3 is 700-800° C., and the pyrolysis time is 10-15 minutes.

[0024] Preferably, in step S4, the high-temperature sintering temperature is 1100-1150° C., and the sintering time is 5-10 minutes.

[0025] Preferably, the temperature of the cooling kiln in step S5 is 600-30°C.

[0026] The second aspect of the present invention provides ceramsite prepared by the coordinated disposal of multiple solid wastes, which is prepared using the above-mentioned method, wherein fly ash from waste incineration is used as a combustion aid during the high-temperature sintering of ceramsite; water plant sludge and iron tailings are used as expansion agents during the high-temperature sintering of ceramsite; the particle size of the prepared ceramsite is 1-2 cm.

[0027] A third aspect of the present invention provides an application of ceramsite prepared by the coordinated disposal of multiple solid wastes in concrete. The ceramsite is prepared using the above method and is used as an additive to concrete to improve the performance of the concrete.

[0028] A fourth aspect of the present invention provides an application of ceramsite prepared by the coordinated disposal of multiple solid wastes in concrete. The ceramsite is prepared using the above method and is used as aggregate for lightweight slats to improve the strength of the lightweight slats.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] (1) Compared with the traditional method for preparing ceramsite by co-processing multiple solid wastes, the method of preparing ceramsite by co-processing multiple solid wastes of the present invention optimizes the raw materials of ceramsite and abandons the traditional method for preparing ceramsite using clay or shale as raw materials. The present invention uses waste incineration fly ash as a combustion aid during high-temperature sintering of ceramsite, and water plant sludge and iron tailings as expansion agents during high-temperature sintering of ceramsite. The particles in waste incineration fly ash are fine and the burned materials are relatively complex. They can absorb most of the heavy metals in the flue gas. Therefore, waste incineration fly ash contains a large amount of heavy metals, especially CaO, which is as high as 30% or more. The large amount of organic matter in water plant sludge can be completely carbonized when the temperature exceeds 600°C. This is the basic principle of using organic matter in sludge to prepare porous ceramsite. The present invention pioneered the use of pure solid waste as raw material to prepare ceramsite, and the high-value-added ceramsite finally obtained can be applied to the construction field, achieving the goal of eliminating waste by eliminating waste, with higher economic and environmental value, and at the same time has great significance for waste reduction, harmlessness and resource disposal.

[0031] (2) The method for preparing ceramsite by co-processing multiple solid wastes of the present invention is compared with the traditional method for preparing ceramsite by co-processing multiple solid wastes. The traditional method for preparing ceramsite by co-processing multiple solid wastes usually uses a single solid waste material and land resources such as clay or shale for preparation. The technology for co-processing ceramsite by co-processing multiple solid wastes can simultaneously utilize multiple different types of solid waste materials for preparation. In this way, in terms of application scope, the technology for co-processing ceramsite by co-processing multiple solid wastes can be more widely applied to various types of solid waste treatment; in terms of disposal quantity, since multiple different types of solid waste materials can be processed simultaneously, the disposal quantity is also relatively larger; in terms of production scale and product application, the technology for co-processing ceramsite by co-processing multiple solid wastes can achieve large-scale production, and the obtained ceramsite products have a wider range of applications. The method for preparing high-strength porous green ceramsite by co-processing pure multiple solid wastes of the present invention has a significant effect on the porosity of ceramsite by adding sludge. Sludge is mainly composed of organic matter, and its ignition loss is much higher than that of fly ash and clay. Therefore, during the ceramsite roasting process, the decomposition and volatilization of sludge will produce a large number of pores. Tests show that as the amount of sludge increases, the porosity of ceramsite first increases and then decreases. When the sludge content reaches 40%, the ceramsite's one-hour water absorption rate reaches a maximum of 8.6%, while at 15%, the one-hour water absorption rate reaches a minimum of 1.2%. This phenomenon indicates that the incorporation of an appropriate amount of sludge can effectively increase the porosity of ceramsite, but excessive sludge can cause the ceramsite to crack during the roasting process, affecting the final product performance. Secondly, the addition of iron ore tailings also has a certain impact on the porosity of ceramsite. Iron ore tailings contain a large amount of iron oxides and other minerals. These substances undergo chemical reactions at high temperatures, forming new mineral phases and generating gases, which form a porous structure. Tests have shown that the incorporation of iron ore tailings can reduce the apparent density and bulk density of ceramsite and increase its porosity.

[0032] The combined use of sewage sludge and iron ore tailings has a more complex effect on the porosity of ceramsite. When used together, they create a synergistic effect, leveraging the sludge's high loss on ignition to increase porosity while the iron ore tailings' chemical composition promotes solid-phase reactions in the ceramsite, improving its strength and porosity uniformity. Research has shown that a 1:1 mass ratio of sewage sludge to iron ore tailings yields higher porosity and better strength. At this point, the ceramsite's water absorption rate is moderate, meeting application requirements without compromising its performance due to excessive water absorption.

[0033] The use of fly ash from landfill as a raw material for producing ceramsite also has a multi-faceted impact on its performance and quality. The addition of fly ash from landfill will change the density and porosity of the ceramsite. Fly ash contains a relatively large amount of inorganic components, such as calcium oxide and silicon oxide. These components react with other components in the ceramsite raw materials during high-temperature roasting to form a porous structure. Therefore, adding an appropriate amount of fly ash can help increase the porosity of the ceramsite, giving it better lightweight properties. However, adding too much fly ash may cause the density of the ceramsite to decrease too much, affecting its mechanical strength. Fly ash particles are small and uniform. Incorporating them into the ceramsite raw materials can help improve the particle size distribution of the ceramsite and improve the uniformity of the finished product. However, the amount of fly ash added needs to be strictly controlled, otherwise it may lead to uneven particle size of the ceramsite, affecting its effectiveness in practical applications.

[0034] The appropriate addition of fly ash from landfill can improve the compressive strength of ceramsite. The active ingredients in fly ash react with other components of the ceramsite raw materials at high temperatures to form reinforcing materials, thereby improving the mechanical properties of the ceramsite. However, when the fly ash content exceeds a certain limit, the compressive strength of the ceramsite decreases, affecting its performance as a building material. The addition of fly ash from landfill also has a certain impact on the durability of ceramsite. Certain components in fly ash may undergo chemical reactions under long-term environmental conditions, resulting in a decrease in the performance of the ceramsite. Therefore, when using fly ash to produce ceramsite, its long-term durability needs to be fully evaluated and tested.

[0035] Surprisingly, experiments have shown that adding fly ash to the ceramsite during its production process forms a glaze on its surface, improving its physical and chemical properties. During the ceramsite sintering process, when temperatures reach a certain level (generally above 1000°C), certain components in the fly ash, such as calcium oxide (CaO), silicon dioxide (SiO2), and aluminum oxide (Al2O3), undergo a melting reaction, forming a liquid phase. This liquid phase spreads across the ceramsite surface and solidifies upon cooling, forming a glaze. Due to surface tension, the molten materials form a uniform, smooth film on the ceramsite surface, which facilitates the formation and even distribution of the glaze. The formation of the glaze effectively binds heavy metals in the fly ash to the ceramsite surface, preventing their leaching and diffusion into the environment, thereby reducing environmental risks. Furthermore, the formation of the glaze improves the ceramsite's water resistance, acid and alkali resistance, and mechanical strength.

[0036] (3) Compared with the traditional off-kiln granulation and calcination method of ceramsite, the off-kiln granulation process of the present invention is more complicated and requires additional pre-treatment equipment such as crushers, grinders, pelletizers, etc., so the cost is higher. At the same time, the energy consumption of off-kiln granulation is also relatively high because it involves more processing steps. The raw materials for traditional off-kiln granulation need to be mixed and ground. The fine powder after grinding enters the granulation stage and is made into spherical particles with uniform particle size through equipment such as disc pelletizers. During the granulation process, adhesives such as polyvinyl alcohol aqueous solution, paraffin and phenolic varnish need to be added to improve the formability of the particles. After the off-kiln granulation is completed, the prepared particles are sent to the rotary kiln for high-temperature sintering. The granulation and pelletization of ceramsite in the kiln mainly occurs in the rotary kiln. The new ceramsite drying kiln adds iron chains to the drying kiln to dry and crush the raw materials, and then innovatively realizes the granulation in the kiln through a special design structure. The basic principle is that the raw materials are continuously tumbled and mixed within the drying kiln through the rotation of the kiln body. Specially designed iron chains gradually conduct heat through the drying, crushing, and granulation processes, ultimately forming raw material pellets with a particle size of 5-15 mm. There are significant differences between in-kiln and off-kiln granulation in terms of process, equipment costs, labor costs and energy consumption, and production flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a process flow chart of the method for preparing ceramsite from multi-component solid wastes of the present invention;

[0038] Figure 2 This is a laboratory process flow chart of the method for preparing ceramsite from multi-component solid wastes of the present invention;

[0039] Figure 3 Schematic diagram of the pilot test line for preparing ceramsite from multi-component solid wastes of the present invention;

[0040] Figure 4 This is the result of the orthogonal test scheme for preparing ceramsite in Example 6 of the experimental example of the present invention;

[0041] Figure 5 This is the heavy metal leaching result of the ceramsite prepared in Example 6 of the experimental example of the present invention;

[0042] Figure 6 It is the heavy metal loss on ignition of the ceramsite prepared in Example 6 of the experimental example of the present invention. DETAILED DESCRIPTION

[0043] Example 1 Figure 1As shown, the present invention proposes a method for preparing ceramsite by co-disposal of multiple solid wastes, comprising the following specific steps: S1, mixing and stirring raw materials: water plant sludge, washless waste incineration fly ash, contaminated soil and iron tailings slag powder are uniformly stirred and mixed in proportion to obtain a stirred mixture; the raw material ratio in step S1 is 15% water plant sludge, 12% iron tailings slag, 15% waste incineration fly ash and 58% contaminated soil, and the fly ash uses unwashed raw ash; in step S1, the raw materials are crushed into coarse particles, then crushed by a crusher and sieved through a nylon sieve to obtain a powdered sample; in this step, the water plant sludge, iron tailings slag, waste incineration fly ash and contaminated soil are uniformly mixed by sufficient stirring.

[0044] Table 1 Detailed information of raw materials

[0045]

[0046] Table 2 Chemical composition of raw materials

[0047]

[0048] S2, granulation molding: the uniformly mixed wet state stirred mixture obtained in step S1 is directly placed in a ceramsite drying and granulation kiln, and granulated in the kiln to obtain raw material balls; the moisture content of the wet state mixture in step S2 is controlled at 70%-80%, the temperature of the ceramsite drying and granulation kiln is 120-160°C, the drying time is 5-10 minutes, and the diameter of the prepared raw material balls is 1-2 cm; in the novel ceramsite drying kiln, iron chains are added to the drying kiln to dry and crush the raw materials, and then granulation is innovatively achieved in the kiln by a specially designed chain;

[0049] S3, low-temperature pyrolysis: The raw material pellets obtained in step S2 are placed in the pyrolysis section of the kiln for low-temperature pyrolysis. The low-temperature pyrolysis temperature in step S3 is 700-800°C and the pyrolysis time is 10-15 minutes. The pyrolysis process can remove most organic pollutants such as pathogens, microorganisms, insect eggs, and dioxins from the fly ash and water plant sludge.

[0050] S4, high-temperature sintering: The pyrolyzed raw balls obtained in step S3 are placed in a calcining kiln for high-temperature sintering. The high-temperature sintering temperature in step S4 is 1100-1150° C., and the sintering time is 5-10 minutes. The high-temperature sintering reaction removes and solidifies most of the heavy metal ions in the raw balls, so that the prepared ceramsite has higher porosity and hardness.

[0051] S5, cooling: the sample obtained in step S4 is passed through a cooling kiln, and the multi-solid waste ceramsite obtained by cooling the sample is taken out; the temperature of the cooling kiln in step S5 is 600-30°C; the cooling kiln gradually and naturally cools the high-temperature ceramsite to prevent it from being suddenly cooled and causing the ceramsite particles to explode.

[0052] Compared to traditional methods for producing ceramsite from solid waste, the present invention's method for producing ceramsite from multi-solid wastes optimizes the raw materials used, eliminating the traditional use of clay or shale as raw materials. This method uses waste incineration fly ash as a combustion aid during the high-temperature sintering of the ceramsite, and water plant sludge and iron ore tailings as expansion agents. The fine particles in waste incineration fly ash and the complex materials burned make it capable of absorbing most heavy metals in flue gas. Consequently, waste incineration fly ash contains significant amounts of heavy metals, particularly CaO, exceeding 30%. The large amount of organic matter in water plant sludge can be completely carbonized at temperatures exceeding 600°C. This is the fundamental principle behind utilizing organic matter in sludge to produce porous ceramsite. This invention pioneers the use of pure solid waste as raw material to produce ceramsite. The resulting high-value-added ceramsite can be applied in the construction industry, achieving the goal of eliminating waste through waste reduction. It possesses higher economic and environmental value and is of significant significance for waste reduction, harmlessness, and resource utilization.

[0053] Example 2 This example provides a method for preparing ceramsite by co-processing multiple solid wastes in a laboratory. Figure 2-3 As shown, the following steps are included:

[0054] S1. Raw material processing: After the water plant sludge is dehydrated in an oven for 24 hours, the moisture content is reduced to 10% to 20%, ensuring the smooth progress of the subsequent processing process. Next, the dried sludge sample is processed by a crusher, crushed into coarse particles, and screened through a 100-mesh sieve to obtain a powder sample with a particle size of less than 0.15 mm. Iron ore tailings, fly ash, and contaminated soil also undergo a similar processing process. After drying in an oven at 60°C for 10 hours, they are processed using a crusher and screened through a 100-mesh nylon sieve to obtain a powder sample with a particle size of less than 0.15 mm.

[0055] S2. Granulation: The pretreated raw materials were mixed according to the specifications of Control Group 1 in Table 3, and 30 ml of deionized water was added and stirred. During the stirring process, it was necessary to ensure that the deionized water and the raw materials were thoroughly mixed. The resulting mixture was then allowed to stand for 12 hours. After the raw materials were aged, they were manually formed into granules with a diameter of 1-2 cm.

[0056] S3, drying the raw balls: the wet raw balls obtained in step S2 are placed for aging for 12 hours, and the aged raw balls are placed in an oven at 105° C. and dried for 12 hours to obtain dry raw balls.

[0057] S4. Preheating of raw balls: Place the dried raw balls obtained in step S3 in a muffle furnace and heat them from 30°C to 400°C for 15 minutes at a heating rate of 10°C per minute. Preheat and fire them. After firing, do not remove the sample to obtain raw balls.

[0058] S5, high temperature sintering: the raw material balls obtained in step S4 are placed in a muffle furnace and preheated from 400°C to 1150°C for 15 minutes at a heating rate of 10°C per minute for high temperature sintering, and cooled at room temperature. After cooling to room temperature, the ceramsite sample is taken out to obtain high-strength porous ceramsite.

[0059] Table 3 Ratio of raw materials of ceramsite samples

[0060]

[0061] Embodiment 3 This embodiment differs from Embodiment 2 in that the specific parameters in step S2 are different.

[0062] S2. Granulation: The pretreated raw materials were mixed according to the specifications of Control Group 2 in Table 1, and 30 ml of deionized water was added and stirred. During the stirring process, it was necessary to ensure that the deionized water and the raw materials were thoroughly mixed. The resulting mixture was then allowed to stand for 12 hours. After the raw materials were aged, they were manually formed into granules with a diameter of 1-2 cm.

[0063] Embodiment 4 This embodiment differs from Embodiment 2 in that the specific parameters in step S2 are different.

[0064] S2. Granulation: The pretreated raw materials were mixed according to the specifications of Control Group 3 in Table 1, and 30 ml of deionized water was added and stirred. During the stirring process, it was necessary to ensure that the deionized water and the raw materials were thoroughly mixed. The resulting mixture was then allowed to stand for 12 hours. After the raw materials were aged, they were manually formed into granules with a diameter of 1-2 cm.

[0065] Embodiment 5 This embodiment differs from Embodiment 2 in that the specific parameters in step S2 are different.

[0066] S2. Granulation: The pretreated raw materials were mixed according to the specifications of Control Group 4 in Table 1, and 30 ml of deionized water was added and stirred. During the stirring process, it was necessary to ensure that the deionized water and the raw materials were thoroughly mixed. The resulting mixture was then allowed to stand for 12 hours. After the raw materials had aged, they were manually formed into granules with a diameter of 1-2 cm.

[0067] Embodiment 6 The difference between this embodiment and embodiment 2 is that the specific parameters in steps S2, S4, and S5 are different.

[0068] S2. Granulation: Mix the pretreated raw materials according to the specifications 1-5 in Table 1, add 30 ml of deionized water, and stir. During the stirring process, ensure that the deionized water and the raw materials are thoroughly mixed. The resulting mixture is then allowed to stand for 12 hours. After the raw materials have aged, they are manually formed into granules with a diameter of 1-2 cm. According to the raw material ratios shown in Table 1, a total of 20 batches of ceramsite were prepared according to the control and orthogonal test procedures.

[0069] S4. Preheating of raw balls: The dried raw balls obtained in step S3 are placed in a muffle furnace and preheated and fired according to an orthogonal experimental design. After firing, the samples are not taken out to obtain raw balls.

[0070] S5, high-temperature sintering: placing the raw material balls obtained in step S4 into a muffle furnace and performing high-temperature sintering according to an orthogonal experimental design, cooling at room temperature, and taking out the ceramsite sample after cooling to room temperature to obtain high-strength porous ceramsite.

[0071] Example 7 This example differs from Example 2 in that this example adopts the ratio of Example 6 for pilot test line operation.

[0072] S1. Mixing and stirring of raw materials: water plant sludge, unwashed waste incineration fly ash, contaminated soil and iron tailings are uniformly mixed at a ratio of 15% water plant sludge, 12% iron tailings, 15% waste incineration fly ash and 58% contaminated soil, and the fly ash is the unwashed raw ash, to obtain a stirred mixture.

[0073] S2, granulation molding: the uniformly mixed mixture with a water content of 70%-80% obtained in step S1 is directly placed in a new type of ceramsite drying and granulation kiln, and the temperature in the kiln is controlled at 120-160°C by adding an iron chain to the drying kiln, and the processes of drying, crushing the raw materials and granulation are carried out to realize the granulation in the kiln to obtain raw material balls.

[0074] S3, low-temperature pyrolysis: The raw material pellets obtained in step S2 enter the pyrolysis section at a temperature of 700-800°C in the kiln for low-temperature pyrolysis treatment to remove most of the pathogens, microorganisms, insect eggs, dioxins and other organic pollutants in the garbage fly ash and water plant sludge.

[0075] S4, high temperature sintering: The pyrolyzed raw material balls obtained in step S3 are placed in a calcining kiln at a temperature of 1100-1150°C for high temperature sintering. Most of the heavy metal ions in the raw material balls are removed and solidified through the high temperature sintering reaction, so that the prepared ceramsite has stronger porosity and hardness.

[0076] S5. Cooling: The sample obtained in step S4 is passed through a cooling kiln at a temperature of 600-160° C., and the multi-component solid waste ceramsite is taken out from the cooled sample.

[0077] Experimental Example 1

[0078] Taking the ceramsite prepared in Example 6 as an example, a test experiment was carried out, and based on the experimental results, a heavy metal leaching result diagram and a heavy metal loss on ignition ratio diagram of the high-strength porous green ceramsite were drawn. As shown in Table 4, the performance test results of 20 orthogonal experimental schemes of high-strength porous green ceramsite were obtained.

[0079] Table 4 Orthogonal test scheme and ceramsite performance test results

[0080]

[0081] Through comprehensive analysis and comparison of the results from orthogonal and single-factor experiments, the optimal preparation conditions for achieving ideal results were determined to be: preheating at 400°C for 15 minutes and sintering at 1150°C for 10 minutes. The optimal raw material ratio for ceramsite is 15% fly ash, 15% municipal sludge, 58% contaminated soil, and 12% iron ore tailings. Ceramsite produced using the specified process and raw material ratio exhibits remarkable properties such as strong stability, extremely low water absorption, lightweight, and high particle strength.

[0082] like Figure 5 As shown in the graph, the solidification rate of heavy metals in the ceramsite after sintering ranges from 91.00% to 100%, indicating that the heavy metal ions are successfully solidified within the ceramsite. Compared with the raw material, the heavy metal leaching rate of the ceramsite is significantly reduced, indicating that the ceramsite has strong resistance to acid leaching.

[0083] By comparing the concentrations of heavy metals in raw materials and ceramsite, evaluating the mass loss of ceramsite before and after sintering, and combining the results of BCR continuous extraction technology test, it is feasible to analyze the degree of heavy metal mass loss of ceramsite during sintering (such as Figure 5 and Figure 6 shown). Combined Figure 5 and Figure 6 It can be seen that during the calcination process, most heavy metal elements experience varying degrees of combustion and gasification losses. The percentages of lost elements such as Ni, Pb, Cd, and Zn can exceed 97%, reaching a maximum when Ni is 100%. While the contents of Cu and Cr are slightly lower, they still exceed 90%.

[0084] Application Example 1

[0085] This embodiment provides an application of ceramsite prepared by the coordinated disposal of multiple solid wastes in concrete. The ceramsite is prepared using the method described in Example 1, and the ceramsite is used as an additive to concrete to improve the performance of the concrete.

[0086] Application of multi-solid waste ceramsite in concrete

[0087] To enhance the lightweight and environmentally friendly properties of concrete, the Guangzhou Huadu District International Green Building Materials Center project employed a concrete production technology that replaced traditional aggregates with multi-solid waste ceramsite. The concrete product's formula includes 10 parts P·O42.5 ordinary Portland cement, 10 parts manufactured sand, 4 parts water, 20 parts multi-solid waste ceramsite, and 0.2 parts admixtures (including water reducers, retarders, air-entraining agents, and early strength agents). Ceramsite concrete may be designated as a strength grade (LC), with LC15 corresponding to C15 for ordinary concrete. Ceramsite concrete can have strengths ranging from LC15 to LC30, but is somewhat lower than ordinary concrete due to the inherent strength of the ceramsite. As shown in Tables 5 and 6, ceramsite concrete has a density of only 60-70% of that of ordinary concrete, significantly reducing the deadweight of the structure. Furthermore, ceramsite concrete has a low thermal conductivity (0.2-0.5 W / (m·K)), making it suitable for energy-saving buildings. The lightweight nature of ceramsite reduces seismic loads and improves building safety. Although ceramsite concrete costs 20-30% more than conventional concrete, it saves on transportation, foundation, and insulation costs. During construction, multi-solid waste ceramsite is mixed with various raw materials in appropriate proportions, then stirred, formed on a vibrating table, and subjected to standard curing. The resulting concrete not only exhibits excellent strength but also significantly reduces the building's deadweight, saving costs. By using multi-solid waste ceramsite, the project reduced the weight of concrete per cubic meter by approximately 20% and also reduced the use of manufactured sand and gravel. This not only improved the building's seismic performance but also brought significant economic and environmental benefits.

[0088] Table 5 Performance and cost data of ordinary concrete

[0089]

[0090] Table 6 Performance and cost data of ceramsite concrete

[0091]

[0092] Application Example 2

[0093] This embodiment provides an application of ceramsite prepared by the coordinated disposal of multiple solid wastes in concrete. The ceramsite is prepared using the method described in Example 1, and the ceramsite is used as aggregate for lightweight slats to improve the strength of the lightweight slats.

[0094] In the building partition project of the International Green Building Materials Center in Huadu District, Guangzhou, fly ash ceramsite was used as the main aggregate for lightweight strips. The project used hollow strips with multi-solid waste ceramsite as the main raw material, with a specification size of 2450mm×600mm×90mm. As shown in Table 7, ceramsite lightweight strips use ceramsite as aggregate and cement as cementitious material. The strength mainly depends on the adhesion between ceramsite and cement. By adding fibers (such as glass fiber and polypropylene fiber), the density can be increased to above 3.0MPa, reducing the construction damage rate. The density of ordinary concrete wall panels is about 2000kg / m 2 The density of ceramsite lightweight board is about 800-1200kg / m 2 . The use of ceramsite lightweight strips can reduce the load on the building structure and save the cost of foundations and beams and columns. The porous structure inside ceramsite effectively blocks heat conduction, and the thermal conductivity is close to that of aerated concrete (0.15-0.25 W / (m·K)). In addition, the sound insulation of ceramsite lightweight strips increases with thickness. The single-layer sound insulation of 120mm board can reach 40dB, and the double-layer hollow structure can reach more than 50dB. In summary, ceramsite lightweight strips are not only light in weight and high in strength, but also have good sound insulation and thermal insulation properties. After the completion of the project, it was tested that all performance indicators of the partition wall met the standard requirements of JG / T 169 "General Technical Requirements for Lightweight Strips for Building Partition Walls". At the same time, due to the use of multi-solid waste ceramsite, the use of traditional clay ceramsite is reduced, arable land resources are protected, and good social and ecological benefits are reflected.

[0095] Table 7 Performance and cost data of ceramsite lightweight strip board

[0096]

[0097] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing ceramsite by co-processing multiple solid wastes, characterized in that: The specific steps include: S1. Mixing and stirring raw materials: water plant sludge, disposable waste incineration fly ash, contaminated soil and iron tailings slag powder are uniformly stirred and mixed in proportion to obtain a stirred mixture; the raw material ratio in step S1 is 15% water plant sludge, 12% iron tailings slag, 15% waste incineration fly ash and 58% contaminated soil; The water plant sludge contains 59.5% organic matter, and the waste incineration fly ash uses unwashed raw ash, with a chloride ion content of 9.89% and a CaO content of 33.05%. The waste incineration fly ash is used as a combustion aid during the high-temperature sintering of ceramsite; the water plant sludge and iron ore tailings are used as expansion agents during the high-temperature sintering of ceramsite. S2, granulation molding: the uniformly mixed wet state stirred mixture obtained in step S1 is directly placed into a ceramsite drying and granulation kiln, and granulated in the kiln to obtain raw material balls; wherein the moisture content of the wet state mixture is controlled at 70%-80%; S3, low-temperature pyrolysis: the raw material balls obtained in step S2 enter the pyrolysis section in the kiln for low-temperature pyrolysis treatment; S4, high temperature sintering: the pyrolyzed raw material balls obtained in step S3 are put into a calcining kiln for high temperature sintering; The high temperature sintering temperature is 1100-1150℃ and the sintering time is 5-10 minutes; S5. Cooling: The sample obtained in step S4 is passed through a cooling kiln, and the multi-component solid waste ceramsite obtained by cooling the sample is taken out.

2. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: In step S1, the raw materials are crushed into coarse particles, which are then pulverized using a crusher and sieved through a nylon sieve to obtain a powdered sample.

3. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: The temperature of the ceramsite drying and granulation kiln is 120-160°C, the drying time is 5-10 minutes, and the diameter of the prepared raw material balls is 1-2 cm.

4. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: In step S3, the low-temperature pyrolysis temperature is 700-800° C., and the pyrolysis time is 10-15 minutes.

5. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: The temperature of the cooling kiln in step S5 is 600-30°C.

6. A ceramsite prepared by co-processing multiple solid wastes, characterized in that: The ceramsite is prepared by the method according to any one of claims 1 to 5; wherein the particle size of the prepared ceramsite is 1 to 2 cm.

7. Application of ceramsite prepared by co-processing multiple solid wastes in concrete, characterized in that: The ceramsite is prepared by the method according to any one of claims 1 to 5, and the ceramsite is used as an additive for concrete to improve the performance of the concrete.

8. Application of ceramsite prepared by co-processing multiple solid wastes in concrete, characterized in that: The ceramsite is prepared by the method according to any one of claims 1 to 5, and the ceramsite is used as aggregate of lightweight slats to improve the strength of the lightweight slats.

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