Method for preparing ceramsite through multi-element solid waste co-treatment and application

Abstract

The invention relates to the technical field of solid waste recycling, in particular to a method for preparing ceramsite through multi-element solid waste co-treatment. The method comprises the following steps: S1, uniformly stirring and mixing waterworks sludge, washing-free waste incineration fly ash, polluted soil and iron tailing slag powder in proportion to obtain a stirred mixture; s2, directly putting the stirred mixture which is uniformly mixed and is in a wet state into a ceramsite drying and granulating kiln, and granulating in the kiln to obtain raw material balls; s3, the raw material balls enter a pyrolysis section in the kiln to be subjected to low-temperature pyrolysis treatment; s4, the pyrolyzed raw material balls enter a calcining kiln to be subjected to high-temperature sintering treatment; and S5, passing the obtained sample through a cooling kiln, and taking out the cooled sample to obtain the multi-element solid waste ceramsite. According to the method, pure solid waste is adopted for preparing the ceramsite, and the links of raw material drying and granulation in traditional ceramsite manufacturing are omitted. The sludge of the waterworks, the waste incineration fly ash, the polluted soil and the iron tailing slag are utilized in a high-valued manner, the energy consumption is low, and less secondary environmental pollutants are generated.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and particularly to a method for co - disposing multiple solid wastes to prepare ceramsite. Background Art

[0002] With the acceleration of China's social sustainable development and urbanization process, the number of urban domestic waste incineration plants and sewage treatment plants is gradually increasing. With the sustainable development of Chinese society and the transformation towards a green economy, more and more metal smelters and mines are facing closure and relocation. The relocation and closure of factories and mines will generate a large amount of solid waste, such as tailings, waste rocks, fly ash, and industrial waste. The surface soil of relocated or closed smelters and mines has been covered by various solid wastes for a long time, and coupled with the scouring of rainwater, most heavy metals accumulate in the soil. It is very difficult for these heavy metals accumulated in the soil to be removed by the dilution and self - purification of the ecological environment.

[0003] According to previous reports, solid wastes such as contaminated soil, tap - water plant sludge, and various metal slags can be used as raw materials or promoters for preparing ceramsite. In recent years, more and more scholars have started to study how to produce ceramsite using solid wastes. However, these studies mainly use a single solid waste as a supplement, with clay or shale as the main raw material for preparing ceramsite. Producing high - temperature sintered ceramsite according to the ratio of these raw materials not only cannot effectively treat solid wastes, but also consumes a large amount of land resources. Preparing ceramsite with a single solid waste usually uses a certain industrial solid waste as the main raw material, such as fly ash, coal gangue, sludge, etc. The preparation of this type of ceramsite makes full use of the chemical composition and physical properties of a single solid waste, and has the characteristics of a single raw material source and relatively stable composition. However, this method is relatively limited in the amount of solid waste treated, mainly restricted by the supply and treatment capacity of a single solid waste. The co - preparation of ceramsite from multiple solid wastes mixes two or more industrial solid wastes in a certain proportion, such as the combination of fly ash and coal gangue, steel slag and sludge, etc. This method can not only dispose of solid wastes to a greater extent, but also optimize the performance of ceramsite through the complementary advantages between different solid wastes. In terms of the amount of solid waste treated, the co - preparation of ceramsite from multiple solid wastes has obvious advantages. It can simultaneously treat multiple solid wastes and greatly increase the total amount of solid waste treated.

[0004] The process of preparing ceramsite from a single solid waste is relatively simple, mainly including steps such as 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 the product performance is also relatively consistent. However, when dealing with large-scale solid waste, this process may face bottlenecks in equipment capacity and efficiency. The process of co-preparing ceramsite from multiple solid wastes is more complex, requiring pretreatment of different solid wastes and optimization of the proportion according to their chemical compositions and physical properties. During the sintering process, the control of temperature and time is also more strict to ensure that the chemical reactions and physical changes between different solid wastes can proceed in coordination, so as to obtain an ideal ceramsite product. Although the process is complex, the co-preparation of ceramsite from multiple solid wastes is more flexible in terms of throughput and can adapt to the treatment requirements of different types and quantities of solid wastes.

[0005] The performance of ceramsite prepared from a single solid waste mainly depends on the characteristics of the solid waste itself. For example, fly ash ceramsite usually has good heat insulation performance, while coal gangue ceramsite has high strength and wear resistance. However, due to the single raw material, the room for improvement in the performance of such ceramsite is limited, and it is difficult to meet multiple performance requirements at the same time, which also limits the further expansion of its solid waste treatment capacity. Due to the interaction of multiple solid waste components, the ceramsite co-prepared from multiple solid wastes often has the advantages of each single solid waste ceramsite and achieves breakthroughs in some performances. The specific performance differences can be reflected from the following indicators: 1. Strength and durability: Through reasonable proportioning and process control, the ceramsite from multiple solid wastes can significantly improve strength and durability while maintaining a low density, while the performance of the ceramsite from a single solid waste may be more limited in this regard;

[0006] 2. Heat insulation performance: Although some single solid wastes such as fly ash ceramsite have good heat insulation performance, the ceramsite from multiple solid wastes may achieve better performance in heat insulation through the synergistic effect of multiple materials;

[0007] 3. Wear resistance and fire resistance: Single solid waste ceramsite such as coal gangue ceramsite has high strength and wear resistance, but the ceramsite from multiple solid wastes may achieve a more balanced development in wear resistance and fire resistance through the complementary advantages of different materials.

[0008] The application fields of single solid waste ceramsite are relatively fixed, mainly determined by its performance characteristics. For example, fly ash ceramsite is commonly used in building thermal insulation materials, while sludge ceramsite is mostly used as filter media in sewage treatment. Although these application fields are stable, it is difficult to achieve a large-scale breakthrough in the volume of solid waste treatment. Ceramsite prepared by co-processing 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 an efficient filter media for sewage treatment and reuse. The wide application of multi-solid waste ceramsite makes it have greater potential in the volume of solid waste treatment, which can meet the needs of different industries for ceramsite, thus further increasing the volume of solid waste treatment.

[0009] Considering from the aspects of environmental and economic benefits, whether it is single solid waste or multi-solid waste to prepare ceramsite, it can effectively dispose of industrial solid waste and reduce environmental pollution, with significant environmental benefits. However, co-processing multiple solid wastes to prepare ceramsite has more advantages in comprehensive utilization of resources. Through the co-utilization of multiple solid wastes, not only can the usage of solid waste be increased, but also the problem that some solid wastes are difficult to be utilized alone can be solved, further improving economic and social benefits.

[0010] However, the traditional out-of-kiln granulation for ceramsite production requires pre-treatment of raw materials outside the rotary kiln, including crushing, grinding, and pelletizing, and then sending the spherical particles into the kiln for swelling and cooling. The process flow is complex. If multiple solid wastes are used as raw materials for ceramsite production and produced according to the traditional out-of-kiln granulation method, corresponding pre-treatment needs to be carried out for various different solid wastes, which requires adding additional pre-treatment equipment, with high equipment cost, labor cost, and energy consumption.

[0011] In summary, there are obvious differences between preparing ceramsite with single solid waste as raw material and co-processing multiple solid wastes to prepare ceramsite in terms of raw material selection, preparation process, product performance, and application fields, especially in the volume of solid waste treatment, each having its own characteristics. Co-processing multiple solid wastes to prepare ceramsite shows greater potential in comprehensive utilization of resources and optimization of product performance, which is an important direction for the future development of ceramsite preparation technology. Therefore, rationally using pure multi-solid waste co-disposal to prepare high-strength porous green ceramsite and applying it to the field of solid waste resource utilization technology has great practical significance for realizing the resource utilization of solid waste and removing soil heavy metal pollutants. Summary of the Invention

[0012] The object of the present invention is to propose a method for co-disposing multiple solid wastes to prepare ceramsite in view of the problems in the background technology, a method for preparing ceramsite by using municipal solid waste incineration fly ash, water treatment plant sludge, contaminated soil, and iron tailings slag, and realizing in-kiln granulation of ceramsite through a new type of ceramsite drying and granulating kiln to solve the problem of ceramsite raw material drying and save the cost of out-of-kiln granulation of ceramsite.

[0013] Technical solution of the present invention. In the first aspect of the present invention, a method for co-disposing multiple solid wastes to prepare ceramsite is provided, which includes the following specific steps: S1. Mixing and stirring of raw materials: Mix tap water plant sludge, non-washed municipal solid waste incineration fly ash, contaminated soil and iron tailings powder in proportion to obtain a stirred mixture. S2. Granulation and forming: Directly put the uniformly mixed and moist stirred mixture obtained in step S1 into a ceramsite drying and granulating kiln, and granulate in the kiln to obtain green pellets. S3. Low-temperature pyrolysis: Subject the green pellets obtained in step S2 to low-temperature pyrolysis treatment in the pyrolysis section of the kiln. S4. High-temperature sintering: Put the pyrolyzed green pellets obtained in step S3 into a calcination kiln for high-temperature sintering treatment. S5. Cooling: Pass the sample obtained in step S4 through a cooling kiln, and take out the cooled sample to obtain multi-solid waste ceramsite.

[0014] Preferably, in step S1, the raw material ratio is 15% tap water plant sludge, 12% iron tailings, 15% municipal solid waste incineration fly ash and 58% contaminated soil, and the fly ash used is the original unwashed ash.

[0015] Preferably, in step S1, the raw materials are crushed into coarse particles, then crushed by a crusher and screened through a nylon sieve to obtain a powdery sample.

[0016] Preferably, in step S2, the water content of the moist mixture is controlled at 70%-80%, the temperature of the ceramsite drying and granulating kiln is 120-160°C, the drying time is 5-10 minutes, and the diameter of the prepared green pellets is 1-2 cm.

[0017] Preferably, in step S3, the low-temperature pyrolysis temperature is 700-800°C, and the pyrolysis time is 10-15 minutes.

[0018] Preferably, in step S4, the high-temperature sintering temperature is 1100-1150°C, and the sintering time is 5-10 minutes.

[0019] Preferably, in step S5, the temperature of the cooling kiln is 600-30°C.

[0020] In the second aspect of the present invention, a ceramsite prepared by co-disposing multiple solid wastes is provided. It is prepared by the above method. Among them, municipal solid waste incineration fly ash 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.

[0021] The third aspect of the present invention provides an application of ceramsite prepared by co-disposing multiple solid wastes in concrete. The ceramsite is prepared by the above method and used as an additive in concrete to improve the performance of the concrete.

[0022] The fourth aspect of the present invention provides an application of ceramsite prepared by co-disposing multiple solid wastes in concrete. The ceramsite is prepared by the above method and used as an aggregate in lightweight panels to improve the strength of the lightweight panels.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects: (1) Compared with the traditional method for preparing ceramsite from solid wastes, the method for preparing ceramsite by co-disposing multiple solid wastes in the present invention optimizes the raw materials of ceramsite and abandons the traditional method of using clay or shale as raw materials. The present invention uses waste incineration fly ash as a combustion aid during the high-temperature sintering of ceramsite, and water treatment plant sludge and iron tailings as expansion agents during the high-temperature sintering of ceramsite. The particles in waste incineration fly ash are fine and the combustion materials are complex. It can adsorb most of the heavy metals in the flue gas. Therefore, waste incineration fly ash contains a large amount of heavy metals, especially CaO up to more than 30%. There is a large amount of organic matter in water treatment plant sludge. When the temperature exceeds 600 °C, the organic matter can be completely carbonized. This is the basic principle for preparing porous ceramsite using the organic matter in the sludge. The present invention innovatively uses pure solid wastes as raw materials to prepare ceramsite, and the finally obtained ceramsite with high added value can be applied to the construction field, achieving the goal of turning waste into useful materials, having higher economic and environmental values, and being of great significance for the reduction, harmlessness, and resource utilization of waste.

[0024] (2) The method for preparing ceramsite by co-disposal of multiple solid wastes of the present invention is compared with the traditional method for preparing ceramsite by co-disposal of multiple solid wastes. The traditional method for preparing ceramsite by co-disposal of multiple solid wastes usually uses a single solid waste material and land resources such as clay or shale for preparation. The technology for co-disposal of ceramsite by co-disposal of multiple solid wastes can simultaneously use multiple different types of solid waste materials for preparation. In this way, in terms of application scope, the technology for co-disposal of ceramsite by co-disposal of 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 treated at the same time, the disposal quantity is relatively larger; in terms of production scale and product application, the technology for co-disposal of ceramsite by co-disposal of 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-disposal of 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. The test shows that with the increase of sludge content, the porosity of ceramsite first increases and then decreases. When the sludge content reaches 40%, the 1-hour water absorption rate of ceramsite is the largest, which is 8.6%; and when the sludge content is 15%, the 1-hour water absorption rate is the smallest, which is 1.2%. This phenomenon shows that the addition of an appropriate amount of sludge can effectively improve the porosity of ceramsite, but excessive sludge will cause the ceramsite to burst during the roasting process, affecting the final performance of the product. Secondly, the addition of iron ore tailings also has a certain effect on the porosity of ceramsite. Iron ore tailings contain more iron oxides and other minerals, which will react chemically at high temperatures to generate new mineral phases and produce gases, thereby forming a porous structure. The test shows that the addition of iron ore tailings can reduce the apparent density and bulk density of ceramsite and increase the porosity of ceramsite.

[0025] The combined use of sludge and iron ore tailings has a more complex effect on the porosity of ceramsite. When the two are used in combination, a synergistic effect can be exerted, which not only increases the porosity by using the high ignition loss of sludge, but also promotes the solid phase reaction of ceramsite by using the chemical composition of iron ore tailings, thereby improving the strength and porosity uniformity of ceramsite. Studies have shown that when the mass ratio of sludge to iron ore tailings is 1:1, the porosity of the obtained ceramsite is higher and the strength is better. At this time, the water absorption rate of ceramsite is moderate, which can meet the use requirements and will not affect the performance of ceramsite due to excessive water absorption.

[0026] The use of garbage fly ash as raw material to produce ceramsite has also had many effects on the performance and quality of ceramsite. The addition of garbage fly ash will change the density and porosity of ceramsite. Fly ash contains more inorganic components, such as calcium oxide, silicon oxide, etc. These components will react with other components in the ceramsite raw materials during high-temperature roasting to form a porous structure. Therefore, adding fly ash in an appropriate amount can help improve the porosity of ceramsite and make it have better lightweight properties. However, excessive addition of fly ash may cause the density of ceramsite to decrease too much, affecting its mechanical strength. Fly ash particles are small and uniform. Adding it to the raw material of ceramsite can help improve the particle size distribution of ceramsite and improve the uniformity of the finished product. However, the amount of fly ash added needs to be strictly controlled, otherwise it may cause uneven particle size of ceramsite, affecting its effect in practical applications.

[0027] The compressive strength of ceramsite can be improved by adding appropriate amounts of fly ash from garbage. The active ingredients in fly ash can react with other ingredients in ceramsite raw materials at high temperatures to generate reinforcing materials, thereby improving the mechanical properties of ceramsite. However, when the fly ash dosage exceeds a certain limit, the compressive strength of ceramsite will decrease, affecting its performance as a building material. The addition of fly ash from garbage also has a certain effect on the durability of ceramsite. Certain components in fly ash may react chemically under long-term environmental effects, resulting in a decrease in the performance of ceramsite. Therefore, when using fly ash to produce ceramsite, its long-term durability needs to be fully evaluated and tested.

[0028] Surprisingly, the experiment showed that adding fly ash as raw material in the preparation of ceramsite can form glaze on its surface and improve its physical and chemical properties. During the sintering process of ceramsite, when the temperature reaches a certain level (generally above 1000℃), some components in fly ash such as calcium oxide (CaO) and silicon dioxide (SiO 2 )、Alumina(Al 2 O 3 ) will undergo a melting reaction to form a liquid phase. These liquid substances spread on the surface of the ceramsite and cool and solidify to form a layer of glaze. Due to the effect of surface tension, the molten substance will form a uniform and smooth film on the surface of the ceramsite, which is conducive to the formation and uniform distribution of the glaze. The formation of glaze enables the surface of the ceramsite to effectively fix the heavy metals in the garbage fly ash, preventing its leaching and diffusion in the environment, thereby reducing its environmental risks. At the same time, the formation of glaze can also improve the water resistance, acid and alkali resistance and mechanical strength of the ceramsite.

[0029] (3) Compared with the traditional method of pelletizing outside the kiln and then calcining for preparing ceramsite by the method of co-disposing multiple solid wastes of the present invention, the technological process of pelletizing outside the kiln is more complex and requires additional pretreatment equipment such as crushers, grinders, pelletizers, etc., so the cost is higher. At the same time, the energy consumption of pelletizing outside the kiln is also relatively high because it involves more processing steps. For the raw materials of traditional pelletizing outside the kiln, the mixed raw materials need to be ground. The fine powder after grinding enters the pelletizing stage and is made into spherical particles with uniform particle size through equipment such as disk pelletizers. During the pelletizing process, adhesives such as aqueous polyvinyl alcohol solution, paraffin wax, and phenolic varnish also need to be added to improve the formability of the particles. After the pelletizing outside the kiln is completed, the formed pellets are sent into a rotary kiln for high-temperature sintering. The pelletizing and ball forming inside the ceramsite kiln mainly occur in the rotary kiln. The new type of ceramsite drying kiln innovatively realizes in-kiln pelletizing by adding iron chain drying and crushing the raw materials in the drying kiln part, and then through a specially designed structure. Its basic principle is that through the rotation of the kiln body, the raw materials continuously tumble and mix inside the drying kiln of the kiln, and the iron chains designed with special structures gradually complete the processes of drying, crushing, and pelletizing of the raw materials through heat conduction, and finally form green balls with particle sizes between 5 - 15 mm. There are significant differences between in-kiln pelletizing and out-of-kiln pelletizing of ceramsite in terms of technological process, equipment cost, labor cost, energy consumption, production flexibility, etc. Description of the Drawings

[0030] Figure 1 is the technological process flow chart of the method for preparing ceramsite from multiple solid wastes of the present invention; Figure 2 is the laboratory technological process flow chart of the method for preparing ceramsite from multiple solid wastes of the present invention; Figure 3 is the schematic diagram of the pilot experiment line for preparing ceramsite from multiple solid wastes of the present invention; Figure 4 is the result of the orthogonal test scheme for preparing ceramsite in Example 6 of the experimental examples of the present invention; Figure 5 is the heavy metal leaching result of the ceramsite prepared in Example 6 of the experimental examples of the present invention; Figure 6 is the heavy metal loss on ignition of the ceramsite prepared in Example 6 of the experimental examples of the present invention. Detailed Embodiments

[0031] Example 1 As 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, unwashed waste incineration fly ash, contaminated soil and iron tailings slag powder are uniformly stirred and mixed in proportion to obtain a stirred mixture; in step S1, the raw material ratio is 15% of water plant sludge, 12% of iron tailings slag, 15% of waste incineration fly ash and 58% of 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.

[0032] Table 1 Detailed information of raw materials

[0033] Table 2 Chemical composition of raw materials

[0034] S2, granulation molding: the uniformly mixed wet state stirred mixture obtained in step S1 is directly placed in a ceramsite drying 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 granulation kiln is 120-160°C, the drying time is 5-10 minutes, and the diameter of the prepared raw material balls is 1-2cm; in the new ceramsite drying kiln, an iron chain is added to the drying kiln part to dry and break the raw materials, and then the kiln granulation is innovatively achieved through a specially designed chain; S3, low-temperature pyrolysis: the raw material balls obtained in step S2 are placed in the pyrolysis section in the kiln for low-temperature pyrolysis treatment; 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 of the organic pollutants such as pathogens, microorganisms, insect eggs and dioxins in the garbage fly ash and the sludge of the water plant; 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 in step S4 is 1100-1150°C, and the sintering time is 5-10 minutes; most of the heavy metal ions in the raw material balls are removed and solidified by the high temperature sintering reaction, so that the prepared ceramsite has stronger porosity and hardness; S5, cooling: passing the sample obtained in step S4 through a cooling kiln, and taking out the multi-solid waste ceramsite obtained from the cooled sample; 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 burst.

[0035] Compared with the traditional method for preparing ceramsite from solid waste, the method for co-disposing multiple solid wastes to prepare ceramsite in the present invention optimizes the raw materials for ceramsite and abandons the use of clay or shale as raw materials in the traditional method for preparing ceramsite. The present invention uses waste incineration fly ash as a combustion aid during the high-temperature sintering of ceramsite, and water treatment plant sludge and iron tailings slag as expansion agents during the high-temperature sintering of ceramsite. The particles in waste incineration fly ash are fine and the combustible materials are complex. Due to its ability to adsorb most heavy metals in flue gas, a large amount of heavy metals, especially CaO, is contained in waste incineration fly ash, with a content of over 30%. There is a large amount of organic matter in water treatment plant sludge. When the temperature exceeds 600 °C, the organic matter can be completely carbonized. This is the basic principle for preparing porous ceramsite using the organic matter in sludge. The present invention innovatively uses pure solid waste as raw materials to prepare ceramsite, and the finally obtained ceramsite with high added value can be applied in the construction field, achieving the goal of treating waste with waste, having higher economic and environmental value, and being of great significance for the reduction, harmlessness, and resource utilization of waste.

[0036] Example 2 This example provides a method for co-disposing multiple solid wastes to prepare ceramsite in a laboratory, as Figures 2-3 shown, including the following steps: S1. Raw material treatment: After dehydrating the water treatment plant sludge in an oven for 24 hours, the water content is reduced to 10% - 20%, ensuring the smooth progress of subsequent treatment processes. Next, the dried sludge sample is processed by a crusher, crushed into coarse particles, and screened through a 100-mesh sieve to finally obtain a powdery sample with a particle size less than 0.15 mm. The iron tailings slag, fly ash, and contaminated soil also undergo a similar treatment 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 finally obtain a powdery sample with a particle size less than 0.15 mm; S2. Granulation and forming: The pretreated raw materials are mixed according to the specifications of Control Group 1 in Table 3, and 30 ml of deionized water is added for stirring. During the stirring process, it is necessary to fully ensure that the deionized water is completely mixed with the raw materials evenly. Then, the obtained mixture is left for 12 hours. After the raw materials are aged, the raw materials need to be manually made into particles with a diameter of 1 - 2 cm.

[0037] S3. Drying of green pellets: The wet green pellets obtained in step S2 are left for aging for 12 h, and the aged green pellets are placed in an oven at 105 °C and dried for 12 h to obtain dry green pellets.

[0038] S4. Preheating of green pellets: The dry green pellets obtained in step S3 are placed in a muffle furnace and heated from 30 °C to 400 °C for preheating for 15 minutes at a heating rate of 10 °C per minute for preheating and firing. After the firing is completed, the sample is not taken out to obtain raw material pellets.

[0039] S5. High-temperature sintering: Place the raw material balls obtained in step S4 into a muffle furnace, preheat from 400°C to 1150°C for 15 minutes with a heating rate of 10°C per minute, conduct high-temperature sintering, cool under room temperature conditions, and take out the ceramsite sample after cooling to room temperature to obtain high-strength porous ceramsite.

[0040] Table 3 Raw material ratio of ceramsite sample

[0041] Example 3 The difference between this example and Example 2 lies in: different specific parameters in step S2.

[0042] S2. Granulation and forming: The pretreated raw materials are mixed according to the specifications of control group 2 in Table 1, and 30 ml of deionized water is added for stirring. During the stirring process, it is necessary to fully ensure that the deionized water and the raw materials are completely mixed evenly. Then the obtained mixture is left for 12 hours. After the raw materials are aged, the raw materials need to be manually made into particles with a diameter of 1 - 2 cm.

[0043] Example 4 The difference between this example and Example 2 lies in: different specific parameters in step S2.

[0044] S2. Granulation and forming: The pretreated raw materials are mixed according to the specifications of control group 3 in Table 1, and 30 ml of deionized water is added for stirring. During the stirring process, it is necessary to fully ensure that the deionized water and the raw materials are completely mixed evenly. Then the obtained mixture is left for 12 hours. After the raw materials are aged, the raw materials need to be manually made into particles with a diameter of 1 - 2 cm.

[0045] Example 5 The difference between this example and Example 2 lies in: different specific parameters in step S2.

[0046] S2. Granulation and forming: The pretreated raw materials are mixed according to the specifications of control group 4 in Table 1, and 30 ml of deionized water is added for stirring. During the stirring process, it is necessary to fully ensure that the deionized water and the raw materials are completely mixed evenly. Then the obtained mixture is left for 12 hours. After the raw materials are aged, the raw materials need to be manually made into particles with a diameter of 1 - 2 cm.

[0047] Example 6 The difference between this example and Example 2 lies in: different specific parameters in steps S2, S4, and S5.

[0048] S2. Granulation and forming: The pretreated raw materials are mixed according to the specifications of No. 1-5 in Table 1, and 30 ml of deionized water is added and stirred. During the stirring process, it is necessary to fully ensure that the deionized water and the raw materials are completely and evenly mixed. Then the obtained mixture is left for 12 hours. After the raw materials are aged, the raw materials need to be manually made into particles with a diameter of 1-2 cm. According to the raw material ratio shown in Table 1, a total of 20 batches of ceramsite were prepared according to the control group and the orthogonal test procedure.

[0049] S4. Preheating of green balls: The dried green balls obtained in step S3 are placed in a muffle furnace and preheated and fired according to the orthogonal experimental design. After the firing is completed, the samples are not taken out to obtain raw material balls.

[0050] S5. High-temperature sintering: The raw material balls obtained in step S4 are placed in a muffle furnace and subjected to high-temperature sintering according to the orthogonal experimental design, cooled at room temperature, and the ceramsite samples are taken out after cooling to room temperature to obtain high-strength porous ceramsite.

[0051] Example 7 The difference between this example and Example 2 is that this example uses the ratio of Example 6 to operate the pilot test line.

[0052] S1. Mixing and stirring of raw materials: The sludge from the water treatment plant, the fly ash from the incineration of non-washable garbage, the contaminated soil and the iron tailings are uniformly stirred and mixed according to the ratio of 15% of the sludge from the water treatment plant, 12% of the iron tailings, 15% of the fly ash from the garbage incineration and 58% of the contaminated soil, and the fly ash is the original ash without washing.

[0053] S2. Granulation and forming: The uniformly mixed stirring mixture with a water content of 70%-80% obtained in step S1 is directly put into a new type of ceramsite drying and granulating kiln. The temperature in the drying kiln is controlled at 120-160 °C by adding iron chains in the drying kiln part, and processes such as drying, crushing the raw materials and granulating are carried out to realize granulation in the ceramsite kiln and obtain green balls.

[0054] S3. Low-temperature pyrolysis: The green balls obtained in step S2 enter the pyrolysis section with a temperature of 700-800 °C in the kiln for low-temperature pyrolysis treatment to remove most of the organic matter pollutants such as germs, microorganisms, insect eggs and dioxins in the fly ash from the garbage and the sludge from the water treatment plant.

[0055] S4. High-temperature sintering: The pyrolyzed green balls obtained in step S3 enter a calcination kiln with a temperature of 1100-1150 °C for high-temperature sintering treatment. Most of the heavy metal ions in the green balls are removed and solidified through the high-temperature sintering reaction, so that the prepared ceramsite has stronger porosity and hardness.

[0056] S5. Cooling: The sample obtained in step S4 is passed through a cooling kiln at a temperature of 600 - 160 °C, and the cooled sample is taken out to obtain the multi-component solid waste ceramsite.

[0057] Experimental Example 1 Taking the ceramsite prepared in Example 6 as an example, a test experiment was carried out, and based on the experimental results, the heavy metal leaching result diagram and the heavy metal loss ratio diagram of the high-strength porous green ceramsite were drawn. The performance test results of 20 kinds of orthogonal experimental schemes of high-strength porous green ceramsite are shown in Table 4.

[0058] Table 4 Orthogonal experimental scheme and ceramsite performance test results

[0059] Through the comprehensive analysis and comparison of the results of orthogonal experiments and single-factor experiments, the optimal preparation conditions to obtain ideal results were determined as: preheating at 400 °C for 15 minutes and sintering at 1150 °C for 10 minutes. The optimal raw material ratio of the ceramsite is 15% fly ash, 15% municipal sludge, 58% contaminated soil, and 12% iron tailings slag. The ceramsite prepared according to the specified process and raw material ratio has remarkable characteristics such as strong stability, extremely low water absorption, light weight, and high particle strength.

[0060] As Figure 5 shown, the solidification rate of heavy metals in the ceramsite after sintering is 91.00% - 100%, indicating that the heavy metal ions have been successfully solidified in the ceramsite. Compared with the raw materials, the heavy metal leaching rate of the ceramsite is significantly reduced, indicating that the prepared ceramsite has strong acid leaching resistance.

[0061] By comparing and analyzing the heavy metal concentrations in the raw materials and the ceramsite, evaluating the mass loss before and after ceramsite sintering, and combining the results of the BCR sequential extraction technology test, it is feasible to analyze the degree of heavy metal mass loss during the ceramsite sintering process (as Figure 5 and Figure 6 shown). Combining Figure 5 and Figure 6 it can be seen that during the roasting process of the ceramsite, most heavy metal elements have different degrees of combustion loss and gasification loss. The percentage of loss elements such as Ni, Pb, Cd, and Zn can exceed 97%, reaching the maximum value when Ni is 100%. The contents of Cu and Cr are slightly lower, but still exceed 90%.

[0062] Application Example 1 This embodiment provides an application of ceramsite prepared by multi-component solid waste co-disposal in concrete. The ceramsite is prepared by the method described in Example 1, and the ceramsite is used as an additive in concrete to improve the performance of concrete.

[0063] Application of multi-component solid waste ceramsite in concrete In the project of the International Green Building Materials Center in Huadu District, Guangzhou, in order to improve the lightweight performance and environmental protection characteristics of concrete, a concrete preparation technology using multi-source solid waste ceramsite to replace traditional aggregates is adopted. The formula of this concrete product includes: 10 parts of P·O42.5 ordinary Portland cement, 10 parts of manufactured sand, 4 parts of water, 20 parts of multi-source solid waste ceramsite, and 0.2 parts of admixtures (including water reducer, retarder, air-entraining agent and early strength agent). The strength grade of ceramsite concrete can be represented by LC. For example, LC15 corresponds to C15 of ordinary concrete. The strength range of ceramsite concrete can be from LC15 to LC30, but it is lower than that of ordinary concrete because the strength of ceramsite itself is lower. As shown in Table 5 and Table 6, the density of ceramsite concrete is only 60-70% of that of ordinary concrete, significantly reducing the structural self-weight. In addition, the thermal conductivity of ceramsite concrete is low (0.2-0.5 W / (m·K)), which is suitable for energy-saving buildings. The lightweight characteristics of ceramsite can reduce seismic loads and enhance building safety. Although the material cost of ceramsite concrete is 20-30% higher than that of ordinary concrete, it can save transportation, foundation and insulation costs. During the construction process, after mixing multi-source solid waste ceramsite with various raw materials in proportion, through stirring, vibrating table forming and standard curing, the finally produced concrete not only has excellent strength performance, but also greatly reduces the building self-weight and saves costs. By using multi-source solid waste ceramsite in this project, the weight of each cubic meter of concrete is reduced by about 20%, and the usage of manufactured sand and crushed stone is also reduced. This not only improves the seismic performance of the building, but also brings significant economic and environmental benefits to the project.

[0064] Table 5 Data Sheet of Performance and Cost of Ordinary Concrete

[0065] Table 6 Data Sheet of Performance and Cost of Ceramsite Concrete

[0066] Application Example 2 This embodiment provides an application of ceramsite prepared by multi-source solid waste co-disposal in concrete. The ceramsite is prepared by the method described in Example 1, and the ceramsite is used as the aggregate of the lightweight slab to improve the strength of the lightweight slab.

[0067] In the building partition wall project of the International Green Building Materials Center in Huadu District, Guangzhou, fly ash ceramsite is used as the main aggregate of lightweight panels. The project uses hollow panels mainly made of multi-source solid waste ceramsite, with the specification size of 2450mm×600mm×90mm. As shown in Table 7, the ceramsite lightweight panel uses ceramsite as the aggregate and cement as the gelling material, and its strength mainly depends on the adhesion between ceramsite and cement. By adding fibers (such as glass fiber, polypropylene fiber), the strength can be increased to more than 3.0MPa, reducing the construction breakage rate. The density of ordinary concrete wall panels is about 2000kg / m 2 , and the density of ceramsite lightweight panels is about 800-1200kg / m 2 . Using ceramsite lightweight panels can reduce the building structure load and save the cost of foundation and beam columns. The internal porous structure of 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 panels increases with the thickness. The single-layer sound insulation of 120mm board can reach 40dB, and the double-layer hollow structure can reach more than 50dB. To sum up, the ceramsite lightweight panel is not only light in weight and high in strength, but also has good sound insulation and heat insulation performance. After the project is completed, after testing, all performance indicators of the partition wall meet the standard requirements of JG / T 169 "General Technical Requirements for Lightweight Panels for Building Partitions". At the same time, due to the use of multi-source solid waste ceramsite, the use of traditional clay ceramsite is reduced, protecting the cultivated land resources and reflecting good social and ecological benefits.

[0068] Table 7 Performance and Cost Data of Ceramsite Lightweight Panels

[0069] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to this. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. A method for preparing ceramsite by co-disposal of multiple solid wastes, characterized in that: The specific steps include: S1. Mixing and stirring raw materials: uniformly mixing water plant sludge, disposable waste incineration fly ash, contaminated soil and iron tailings slag powder according to proportion to obtain a stirred mixture; S2, granulation and 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; S3, low-temperature pyrolysis: the raw material balls obtained in step S2 are placed in 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; S5, cooling: passing the sample obtained in step S4 through a cooling kiln, and taking out the multi-solid waste ceramsite obtained from the cooled sample.

2. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: The raw material ratio in step S1 is 15% of waterworks sludge, 12% of iron ore tailings, 15% of waste incineration fly ash and 58% of contaminated soil, and the fly ash adopts unwashed raw ash.

3. 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.

4. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: In step S2, the moisture content of the wet mixture is controlled at 70%-80%, the temperature of the ceramsite drying 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.

5. 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.

6. The method for preparing ceramsite by co-processing multiple solid wastes according to claim 1, characterized in that: In step S4, the high temperature sintering temperature is 1100-1150° C., and the sintering time is 5-10 minutes.

7. 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.

8. A ceramsite prepared by co-disposal of multiple solid wastes, characterized in that: The method according to any one of claims 1 to 7 is used for preparation; wherein fly ash from waste incineration is used as a combustion aid during high-temperature sintering of ceramsite; sewage sludge and iron tailings are used as expansion agents during high-temperature sintering of ceramsite; and the particle size of the prepared ceramsite is 1 to 2 cm.

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

10. Application of ceramsite prepared by co-treatment of multiple solid wastes in concrete, characterized in that: The ceramsite is prepared by the method according to any one of claims 1 to 7, and the ceramsite is used as aggregate of lightweight slats to improve the strength of the lightweight slats.

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