Lightweight water-retaining material prepared from sludge incineration slag and preparation method thereof

Abstract

The application relates to the technical field of sludge recycling, and particularly discloses a lightweight water-retaining material prepared from sludge incineration slag and a preparation method thereof. The preparation method for preparing the lightweight water-retaining material from the sludge incineration slag comprises the following steps: drying and grinding sludge incineration slag, red mud, waste mud and a pore-forming agent respectively, the mass proportion of the sludge incineration slag reaches 40-60%, an alkali activator with solutes of Na2SiO3 and NaOH is additionally configured, the alkali activator is sprayed onto mixed powder, granulation is carried out to form particles, pre-calcination and high-temperature calcination at a temperature of 950-1100 DEG C are carried out after drying, and the lightweight water-retaining material is obtained after cooling. In the scheme, the sludge incineration slag is used as a main raw material, the red mud, rice husks and lake bottom silt are used as auxiliary materials, the sintering temperature is reduced by adding the red mud, the porosity is increased by simultaneously adding the pore-forming agent, the prepared finished product has the advantages of light weight, porosity, large specific surface area and high water absorption, the purpose of lightweight water retention is achieved, the utilization rate of solid waste resources is improved, and the development of circular economy is promoted.

Description

Technical Field

[0001] This application relates to the field of sludge reuse technology, specifically to a lightweight water-retaining material prepared from sludge incineration slag and its preparation method. Background Technology

[0002] The rapidly increasing volume of urban sludge is facing growing pressure in its treatment and disposal. Sludge incineration is a common method of sludge disposal, effectively removing organic matter and harmful substances and significantly reducing sludge volume. However, the efficient disposal and comprehensive utilization of sludge incineration ash has become a pressing issue. Sludge incineration ash refers to the inorganic residue left after sludge has undergone high-temperature combustion. It is rich in elements such as silicon and aluminum, with the combined content of SiO2 and Al2O3 typically exceeding 70%. Currently, landfilling remains the primary disposal method for sludge incineration ash. Given the scarcity of land resources and significant environmental risks, landfill space in many cities is dwindling, making zero-landfill resource utilization a key research focus in the field of sludge incineration. The main directions for the resource utilization of sludge incineration ash include phosphorus recovery, brick making, use as lightweight aggregate, concrete admixture, and adsorbent.

[0003] Patent application CN115322007A describes a method for producing ceramsite from sludge incineration slag. The method involves drying water-containing sludge, slag, clay, fly ash, iron oxide, and zeolite to a constant weight, crushing and sieving them, adding water to mix them until they are moist, extruding them into shape, and then drying and calcining them to obtain ceramsite. However, clay is the material with the largest mass percentage among the raw materials, while sludge incineration slag does not have the largest mass percentage and only accounts for 20-32.6% of the total mass. Therefore, the treatment efficiency of sludge incineration slag is not high. Summary of the Invention

[0004] This application aims to explore new pathways for the resource utilization of sludge incineration ash, thereby achieving the harmless, reduced-volume, stabilized, and resource-oriented disposal of sludge incineration ash. This will reduce landfill space usage, conserve land resources, and mitigate environmental risks. Furthermore, the addition of red mud, rice husks, and silt, among other solid wastes, enables effective resource utilization, reduces solid waste emissions, and generates high-value-added products, achieving high-value utilization of waste materials.

[0005] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0006] Raw material pretreatment: The sludge incinerator slag, red mud, waste mud, and pore-forming agent are dried separately.

[0007] Grinding: Dry sludge incinerator slag, red mud, waste mud, and pore-forming agent are ground into powders to obtain sludge incinerator slag powder, red mud powder, waste mud powder, and pore-forming agent powder.

[0008] Prepare the alkaline activator: Prepare a mixed aqueous solution of Na2SiO3 and NaOH as the solute, and cool it to 5-50℃.

[0009] Granulation and molding: According to the mass proportions, 50-60 parts of sludge incinerator slag powder, 20-25 parts of red mud powder, 20-25 parts of waste mud powder, and 10-15 parts of pore-forming agent powder are mixed and granulated. During the granulation process, the alkali activator is sprayed onto the mixed powder to form granules.

[0010] Aging: Store the particles at room temperature for 12-36 hours.

[0011] Drying: Dry the aged granules.

[0012] Pre-calcination: Heat the dried granules to 300-400℃.

[0013] High-temperature firing: The firing temperature is 950-1100℃, and the firing time is 5-15 minutes.

[0014] After calcination and cooling, the lightweight water-retaining material is obtained.

[0015] The slag from sludge incineration contains various inorganic minerals such as SiO2, Al2O3, and Fe2O3, exhibiting a composition similar to clay. From an elemental perspective, sludge incineration slag is suitable as a raw material for synthesizing lightweight water-retaining materials (which can be in the form of ceramsite). This method involves activating the sludge incineration slag with alkali and then sintering it to prepare the lightweight water-retaining material. This scheme also utilizes red mud, a high-alumina material, which facilitates the formation of a glassy phase during ceramsite sintering, thereby promoting mass transfer in the ceramsite, lowering the calcination temperature, saving energy, and addressing the problem of environmental pollution caused by the accumulation of large amounts of red mud and the resulting alkaline substances. By adding red mud, the sintering temperature is lowered, energy is saved, and the volatilization of heavy metals from the sludge incineration slag is reduced during sintering. Simultaneously, a pore-forming agent is added to increase porosity, resulting in a finished product that is lightweight, porous, has a large specific surface area, and high water absorption, achieving the goal of lightweight water retention. In the above technical scheme, the mass proportion of sludge incineration slag reaches 40-60%, resulting in high efficiency in the disposal of sludge incineration slag.

[0016] During the alkali activation process, the alkali activator reacts chemically with silica, metal oxides, and metal ions in the sludge incinerator slag. For example, NaOH reacts with SiO2 to form Na2SiO3, and NaOH reacts with Al2O3 to form NaAlO2. NaOH also reacts with heavy metal ions, and the products are solidified in the reaction system. Na2SiO3 and Ca... 2+ Mg 2+The reaction process generates CaSiO3, MgSiO3, and Na2SiO3, which in turn react with heavy metal ions. The products are solidified within the reaction system. After this reaction, the heavy metals in the slag are also encapsulated and fixed within the system, reducing their potential environmental harm and improving the safety of this lightweight water-retaining material. The activated slag has a higher specific surface area, more uniform pore size distribution, and better mechanical strength, resulting in ceramsite with excellent water absorption, hardness, and durability. Experiments have shown that the bulk density of the ceramsite is 400-500 kg / cm³. 3 The compressive strength of the cylinder is 1.5-2.5 MPa, and the water absorption rate is 30-50%.

[0017] A preferred embodiment of the method for preparing lightweight water-retaining materials from sludge incineration slag is that the sludge is one or more of lake bottom silt, river bottom mud, and construction waste mud.

[0018] By adopting the above technical solution, these waste sludges contain substances such as silica and silicates, which can react with alkaline activators. This option provides a solution for treating lake bottom silt, river bottom mud and construction waste mud, reducing solid waste emissions, increasing product added value, and realizing high-value utilization of waste.

[0019] A preferred embodiment of the method for preparing lightweight water-retaining materials from sludge incineration slag is that the pore-forming agent is one or both of raw rice husk and carbonized rice husk.

[0020] By employing the above technical solution, using one or both of raw rice husks and carbonized rice husks as pore-forming agents, the impact of red mud forming a glassy phase that blocks pores during the sintering of ceramic particles is reduced. This pore-forming agent increases porosity, and inorganic components in the rice husks, such as silicates, also participate in the formation process of the ceramic particles, positively impacting their structure and properties. Raw rice husks refer to rice husks removed from paddy rice that have not undergone carbonization or other chemical treatments; they are generally yellow. Carbonized rice husks refer to the charred material formed by heating raw rice husks below their ignition point, causing incomplete combustion.

[0021] A preferred embodiment of the method for preparing lightweight water-retaining materials from sludge incineration slag is that, in the alkali activator, the mass concentration of Na2SiO3 is 60-75% and the mass concentration of NaOH is 6-8%.

[0022] By adopting the above technical solution, high concentrations of Na2SiO3 can react with Ca in sludge incineration slag and waste sludge. 2 + Mg 2+It reacts with other heavy metal ions to form water-insoluble silicates. Lower concentrations of NaOH can react with SiO2 and other metal ions to form water-insoluble silicates. The reaction products can encapsulate the heavy metal elements. The alkaline activator at this concentration has high safety and is suitable for vegetation planting.

[0023] A preferred embodiment of the method for preparing lightweight water-retaining materials from sludge incineration slag is as follows: during the granulation process, the alkali activator is sprayed onto the mixed powder, and granules are formed by rolling, maintaining the moisture content of the granules at 18-20%, and finally forming particles with a diameter of 5-10 mm.

[0024] By adopting the above technical solution, the alkali activator has high permeability to the powder and can react with the sludge, incinerator slag, waste mud, red mud and other materials in the powder, playing a role in binding the raw materials. Through continuous spraying of the alkali activator and continuous rolling of the granules, the granules gradually become larger, thus achieving granulation.

[0025] A preferred embodiment of the method for preparing lightweight water-retaining materials from sludge incineration slag is that the pre-calcination specifically involves: starting preheating at 40-60℃, increasing the temperature to 300-400℃ at a heating rate of 8-12℃ / min, and preheating for 15-25min.

[0026] By adopting the above technical solution, the pre-firing step of this parameter can remove moisture, remove harmful gases, decompose organic matter, improve the adhesion of each raw material, and fix the shape of the product.

[0027] Secondly, this application also proposes a lightweight water-retaining material prepared from sludge incineration slag, and adopts the following technical solution.

[0028] A lightweight water-retaining material prepared from sludge incineration slag is obtained according to the above method.

[0029] By adopting the above technical solution, the prepared lightweight water-retaining material has the advantages of being lightweight and porous, having a large specific surface area, and being able to adsorb a large amount of water and nutrients.

[0030] A preferred embodiment of the lightweight water-retaining material prepared from the sludge incineration slag is ceramsite with a bulk density of 400-500 kg / cm³. 3 The compressive strength of the cylinder is 1.5-2.5 MPa, and the water absorption rate is 30-50%.

[0031] By adopting the above technical solutions, lightweight water-retaining materials are lightweight, porous, and have a high water absorption rate. They can be applied to flower nutrient soil to realize the high-value utilization of sludge incineration slag.

[0032] In summary, this application proposes a method for preparing ceramsite using sludge incineration slag as the main raw material and red mud, rice husks, and other pore-forming agents, as well as silt and other waste mud, as auxiliary materials. This method achieves synergistic treatment of multiple solid wastes, reducing environmental pollution and improving resource utilization. Alkali activation treatment alters the physical and chemical properties of the slag, resulting in ceramsite with typically high porosity, low density, and good permeability. Adding red mud facilitates the formation of a glassy phase in the ceramsite during sintering, thereby promoting mass transfer and lowering the sintering temperature. Simultaneously, the addition of red mud reduces the volatility of heavy metals in the sludge incineration slag during sintering, resulting in low leaching. However, the formation of the glassy phase can also clog pores. Therefore, rice husks are used as a pore-forming agent. The combustion of its organic components releases heat and gas, forming pores of a certain size and increasing porosity. Furthermore, the inorganic components in rice husks, such as silicates, also participate in the formation process of the ceramsite, positively impacting its structure and properties.

[0033] Compared with other methods for preparing ceramsite from sludge incineration slag, this method uses sludge incineration slag as the main raw material and red mud, rice husks, and lake bottom silt as auxiliary materials. The synergistic treatment of multiple solid wastes not only reduces the proportion of other natural materials and lowers production costs, but also has the advantages of environmental protection and sustainability, reduces waste emissions, improves the utilization rate of solid waste resources, and promotes the development of a circular economy. Attached Figure Description

[0034] Figure 1 This is an overall structural diagram of the lightweight water-retaining material prepared from sludge incineration slag in Example 1.

[0035] Figure 2 The diagram shows the internal pore size of the lightweight water-retaining material prepared from the sludge incineration slag of Example 1. Detailed Implementation

[0036] Example 1

[0037] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0038] Raw material pretreatment: The sludge incinerator slag, red mud, waste mud, and pore-forming agent were dried by baking at 105℃ for 24 hours. The waste mud was lake bottom silt. The pore-forming agent was raw rice husk.

[0039] Grinding: Using a ball mill, dry sludge incinerator slag, red mud, waste mud, and pore-forming agent are ground for 50-60 minutes respectively, ground into powder, and passed through a 100-mesh sieve to obtain sludge incinerator slag powder, red mud powder, waste mud powder, and pore-forming agent powder.

[0040] Preparation of alkali activator: Weigh 70 parts Na2SiO3 and 7 parts NaOH by mass, add 23 parts water and mix to dissolve. Since the dissolution of solid sodium hydroxide releases a large amount of heat, the alkali activator is generally prepared 24 hours before the test and cooled to room temperature before use. This room temperature can be 5 to 50°C.

[0041] Granulation and molding: According to the mass proportions, 55 parts of sludge incinerator slag powder, 22 parts of red mud powder, 22 parts of waste mud powder, and 12 parts of pore-forming agent powder are mixed and put into a disc granulator for granulation. During the granulation process, the prepared alkali activator is sprayed onto the mixed powder through a spray bottle. Through continuous disc rolling, granules are formed. The moisture content of the granules is maintained at about 18-20%, and finally spherical particles with a diameter of 5-10mm are formed.

[0042] Aging: The spherical particles are aged by storing them at room temperature for 24 hours.

[0043] Drying: Dry the aged granules at 105℃ to constant weight.

[0044] The sintering process then takes place in a muffle furnace, which is divided into two stages: pre-calcination and high-temperature roasting, as described below.

[0045] Pre-calcination: In a muffle furnace, the dried particles are preheated from 50°C to 350°C at a heating rate of 10°C / min for 20 min.

[0046] High-temperature firing: The firing temperature is 1030℃ and the firing time is 10 minutes.

[0047] After the sintering process is completed, the pellets are removed from the muffle furnace and cooled to room temperature to obtain the lightweight water-retaining material, such as... Figure 1 The lightweight water-retaining material is ceramsite, and the internal pore structure of the ceramsite is referenced. Figure 2 It has abundant pores.

[0048] Example 2

[0049] This embodiment prepares a lightweight water-retaining material from sludge incineration slag. The method used is basically the same as that in Embodiment 1, except that the sludge in this embodiment is riverbed sediment, and the raw material ratio and process parameters have been adjusted, as detailed below.

[0050] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0051] Raw material pretreatment: The sludge incinerator slag, red mud, waste mud, and pore-forming agent were dried by baking at 105℃ for 24 hours.

[0052] Grinding: Using a ball mill, dry sludge incinerator slag, red mud, waste mud, and pore-forming agent are ground for 50-60 minutes respectively, ground into powder, and passed through a 100-mesh sieve to obtain sludge incinerator slag powder, red mud powder, waste mud powder, and pore-forming agent powder.

[0053] Preparation of alkali activator: Weigh 60 parts Na2SiO3 and 8 parts NaOH by mass, add 32 parts water and mix to dissolve. Since the dissolution of solid sodium hydroxide releases a large amount of heat, the alkali activator is generally prepared 24 hours before the test and cooled to room temperature before use. This room temperature can be 5 to 50°C.

[0054] Granulation and molding: According to the mass proportions, 60 parts of sludge incinerator slag powder, 20 parts of red mud powder, 20 parts of waste mud powder, and 10 parts of pore-forming agent powder are mixed and put into a disc granulator for granulation. During the granulation process, the prepared alkali activator is sprayed onto the mixed powder through a spray bottle. Through continuous disc rolling, granules are formed. The moisture content of the granules is maintained at about 18-20%, and finally spherical particles with a diameter of 5-10mm are formed.

[0055] Aging: The spherical particles are aged by storing them at room temperature for 24 hours.

[0056] Drying: Dry the aged granules at 105℃ to constant weight.

[0057] The sintering process then takes place in a muffle furnace, which is divided into two stages: pre-calcination and high-temperature roasting, as described below.

[0058] Pre-calcination: In a muffle furnace, the dried particles are preheated from 50°C to 400°C at a heating rate of 10°C / min for 15 minutes.

[0059] High-temperature firing: The firing temperature is 1100℃ and the firing time is 5 minutes.

[0060] After the sintering process is completed, the pellets are removed from the muffle furnace and cooled to room temperature to obtain the lightweight water-retaining material, which is ceramsite.

[0061] Example 3

[0062] This embodiment prepares a lightweight water-retaining material from sludge incineration slag. The method used is basically the same as that in Embodiment 1, except that the sludge in this embodiment is construction waste mud, the pore-forming agent is carbonized rice husk, and the raw material ratio and process parameters are adjusted as follows.

[0063] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0064] Raw material pretreatment: The sludge incinerator slag, red mud, waste mud, and pore-forming agent were dried by baking at 105℃ for 24 hours.

[0065] Grinding: Using a ball mill, dry sludge incinerator slag, red mud, waste mud, and pore-forming agent are ground for 50-60 minutes respectively, ground into powder, and passed through a 100-mesh sieve to obtain sludge incinerator slag powder, red mud powder, waste mud powder, and pore-forming agent powder.

[0066] Preparation of alkali activator: Weigh 75 parts Na2SiO3 and 6 parts NaOH by mass, add 19 parts water and mix to dissolve. Since the dissolution of solid sodium hydroxide releases a large amount of heat, the alkali activator is generally prepared 24 hours before the test and cooled to room temperature before use. This room temperature can be 5 to 50°C.

[0067] Granulation and molding: According to the mass proportions, 50 parts of sludge incinerator slag powder, 25 parts of red mud powder, 25 parts of waste mud powder, and 15 parts of pore-forming agent powder are mixed and placed into a disc granulator for granulation. During the granulation process, the prepared alkali activator is sprayed onto the mixed powder through a spray bottle. Through continuous disc rolling, granules are formed, and the moisture content of the granules is maintained at about 18-20%. Finally, spherical particles with a diameter of 5-10mm are formed.

[0068] Aging: The spherical particles are aged by storing them at room temperature for 24 hours.

[0069] Drying: Dry the aged granules at 105℃ to constant weight.

[0070] The sintering process then takes place in a muffle furnace, which is divided into two stages: pre-calcination and high-temperature roasting, as described below.

[0071] Pre-calcination: In a muffle furnace, the dried particles are preheated from 50°C to 300°C at a heating rate of 10°C / min for 25 minutes.

[0072] High-temperature firing: The firing temperature is 950℃ and the firing time is 15 minutes.

[0073] After the sintering process is completed, the pellets are removed from the muffle furnace and cooled to room temperature to obtain the lightweight water-retaining material, which is ceramsite.

[0074] Comparative Example 1

[0075] This comparative example prepares a lightweight water-retaining material from sludge incineration slag. The method used is basically the same as in Example 1, except that the raw materials in this comparative example do not contain red mud; instead, an equal mass of waste mud is used to replace red mud. The specific method for preparing the lightweight water-retaining material in this comparative example is as follows.

[0076] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0077] Raw material pretreatment: The sludge incinerator slag, waste sludge, and pore-forming agent were dried separately by baking at 105℃ for 24 hours. The waste sludge was lake bottom silt. The pore-forming agent was raw rice husk.

[0078] Grinding: Using a ball mill, dry sludge incinerator slag, waste mud, and pore-forming agent are ground into powder for 50-60 minutes respectively, and then passed through a 100-mesh sieve to obtain sludge incinerator slag powder, waste mud powder, and pore-forming agent powder.

[0079] Preparation of alkali activator: Weigh 70 parts Na2SiO3 and 7 parts NaOH by mass, add 23 parts water and mix to dissolve. Since the dissolution of solid sodium hydroxide releases a large amount of heat, the alkali activator is generally prepared 24 hours before the test and cooled to room temperature before use. This room temperature can be 5 to 50°C.

[0080] Granulation and molding: According to the mass proportions, 55 parts of sludge incinerator slag powder, 44 parts of waste sludge powder, and 12 parts of pore-forming agent powder are mixed and put into a disc granulator for granulation. During the granulation process, the prepared alkali activator is sprayed onto the mixed powder through a spray bottle. Through continuous disc rolling, granules are formed. The moisture content of the granules is kept at about 18-20%, and finally spherical particles with a diameter of 5-10mm are formed.

[0081] Aging: The spherical particles are aged by storing them at room temperature for 24 hours.

[0082] Drying: Dry the aged granules at 105℃ to constant weight.

[0083] The sintering process then takes place in a muffle furnace, which is divided into two stages: pre-calcination and high-temperature roasting, as described below.

[0084] Pre-calcination: In a muffle furnace, the dried particles are preheated from 50°C to 350°C at a heating rate of 10°C / min for 20 min.

[0085] High-temperature firing: The firing temperature is 1030℃ and the firing time is 10 minutes.

[0086] After the sintering process is completed, the pellets are removed from the muffle furnace and cooled to room temperature to obtain the lightweight water-retaining material, which is ceramsite.

[0087] Comparative Example 2

[0088] This comparative example prepares a lightweight water-retaining material from sludge incineration slag. The method used is basically the same as that in Example 1, except that the raw materials in this comparative example do not contain pore-forming agents, and waste sludge of equal mass is used instead of pore-forming agents.

[0089] The specific method for preparing lightweight water-retaining materials in this comparative example is as follows.

[0090] A method for preparing lightweight water-retaining materials from sludge incineration slag, the method comprising:

[0091] Raw material pretreatment: The sludge incinerator slag, red mud, and waste mud were dried by baking at 105℃ for 24 hours. The waste mud was lake bottom silt.

[0092] Grinding: Using a ball mill, dry sludge incinerator slag, red mud, and waste mud are ground for 50-60 minutes respectively to form powder, which is then passed through a 100-mesh sieve to obtain sludge incinerator slag powder, red mud powder, and waste mud powder.

[0093] Preparation of alkali activator: Weigh 70 parts Na2SiO3 and 7 parts NaOH by mass, add 23 parts water and mix to dissolve. Since the dissolution of solid sodium hydroxide releases a large amount of heat, the alkali activator is generally prepared 24 hours before the test and cooled to room temperature before use. This room temperature can be 5 to 50°C.

[0094] Granulation and molding: According to the mass proportions, 55 parts of sludge incinerator slag powder, 22 parts of red mud powder, and 34 parts of waste mud powder are mixed and put into a disc granulator for granulation. During the granulation process, the prepared alkali activator is sprayed onto the mixed powder through a spray bottle. Through continuous disc rolling, granules are formed. The moisture content of the granules is maintained at about 18-20%, and finally spherical particles with a diameter of 5-10mm are formed.

[0095] Aging: The spherical particles are aged by storing them at room temperature for 24 hours.

[0096] Drying: Dry the aged granules at 105℃ to constant weight.

[0097] The sintering process then takes place in a muffle furnace, which is divided into two stages: pre-calcination and high-temperature roasting, as described below.

[0098] Pre-calcination: In a muffle furnace, the dried particles are preheated from 50°C to 350°C at a heating rate of 10°C / min for 20 min.

[0099] High-temperature firing: The firing temperature is 1030℃ and the firing time is 10 minutes.

[0100] After the sintering process is completed, the pellets are removed from the muffle furnace and cooled to room temperature to obtain the lightweight water-retaining material, which is ceramsite.

[0101] Experimental Example 1

[0102] The ceramsite prepared in Examples 1-3 and Comparative Examples 1-2 was tested, and some of its properties were tested as follows: bulk density was 400-500 kg / cm³. 3 The compressive strength of the cylinder is 1.5-2.5 MPa, and the water absorption rate is 30-50%.

[0103] Table 1 Test data of various expanded clay aggregate properties

[0104]

[0105]

[0106] According to Table 1, the bulk density, compressive strength and water absorption rate of the expanded clay particles in Examples 1-3 are comparable, and all have achieved good results, making them suitable as water-retaining materials for flower roots.

[0107] Compared to Example 1, Comparative Example 1 did not contain red mud in its raw materials; instead, it used waste mud of the same mass instead. The bulk density of the ceramsite in Comparative Example 1 was comparable to that in Example 1, but the compressive strength was significantly lower, and the water absorption rate was slightly higher. Overall, the ceramsite of Example 1 was lightweight, had high water absorption, and exhibited greater mechanical strength. This aligns with the argument that red mud facilitates the formation of the glassy phase during the sintering process of ceramsite, thereby promoting mass transfer and enhancing the mechanical strength of the ceramsite.

[0108] Compared to Example 1, Comparative Example 2 did not contain a pore-forming agent in its raw materials; instead, it used an equal mass of waste mud instead. The bulk density of the expanded clay particles in Comparative Example 2 was increased due to its fewer pores. The expanded clay particles in Comparative Example 2 were heavier, which would limit their application, such as as a water-retaining material for flowers, due to the greater pressure they exert on plant roots. The compressive strength of the expanded clay particles in Comparative Example 2 was comparable to that in Example 1, both exhibiting good mechanical strength. However, the water absorption rate of the expanded clay particles in Comparative Example 2 was significantly lower than that in Example 1, which somewhat limited their application as a water-retaining material for flowers.

[0109] Summarize

[0110] This application aims to improve the utilization rate of sludge incineration ash and reduce environmental pollution caused by the large-scale stockpiling of sludge incineration ash and red mud. It proposes using sludge incineration ash as the main raw material and red mud, rice husks, and silt as auxiliary materials to prepare ceramsite, thereby improving the resource utilization of solid waste and reducing production costs. This application solves the problems of high production costs and waste of mineral resources associated with traditional ceramsite preparation from non-renewable resources. Furthermore, this application utilizes a scientifically sound design method to leverage the interaction between sludge incineration ash and red mud, rice husks, and silt, facilitating the comprehensive utilization of various solid waste materials, reducing production costs, minimizing the waste of non-renewable mineral resources, and ultimately improving the resource utilization rate of solid waste while protecting the ecological environment. The ceramsite prepared using this solid waste can be applied to flower potting soil, enabling the resource utilization of solid waste to not only solve the environmental pollution problems caused by solid waste landfill but also create diverse ecological value.

[0111] The above are merely some embodiments of this application. The scope of protection of this application is not limited to the above embodiments. For those skilled in the art, any improvements and modifications made without departing from the inventive design of this application should also fall within the scope of protection of this application.

Claims

1. A method for producing a lightweight water retaining material from sludge incineration slag, characterized by, The method comprises: Raw material pretreatment: drying sludge incinerator slag, red mud, waste mud, and pore-forming agent respectively; Grinding: grinding the dried sludge incinerator slag, red mud, waste mud, and pore-forming agent into powder respectively to obtain sludge incinerator slag powder, red mud powder, waste mud powder, and pore-forming agent powder; Preparation of alkali activator: preparing a mixed aqueous solution with Na2SiO3 and NaOH as solutes, and cooling to 5-50℃; Granulation and molding: according to the mass fraction, mixing sludge incinerator slag powder 50-60 parts, red mud powder 20-25 parts, waste mud powder 20-25 parts, and pore-forming agent powder 10-15 parts for granulation, and in the granulation process, spraying the alkali activator onto the mixed powder to form particles; Aging: storing the particles at room temperature for 12-36 hours; Drying: drying the aged particles; Pre-calcination: heating the dried particles to 300-400℃; High-temperature calcination: calcination temperature is 950-1100℃, and calcination time is 5-15min; Cooling after calcination to obtain the light water-retaining material; In the alkali activator, the mass concentration of Na2SiO3 is 60-75%, and the mass concentration of NaOH is 6-8%; In the granulation process, the alkali activator is sprayed onto the mixed powder to form granules by rolling, and the moisture content of the granules is maintained at 18-20%, and finally particles with a diameter of 5-10mm are formed; The pre-calcination specifically comprises: preheating from 40-60℃, heating to 300-400℃ at a heating rate of 8-12℃ / min, and preheating time is 15-25min.

2. The method according to claim 1, wherein the method is characterized by, The waste mud is one or more of lake bottom sludge, river channel sludge, and construction waste mud.

3. The method according to claim 1, wherein the method is characterized by, The pore-forming agent is one or both of raw rice husk and carbonized rice husk.

4. A lightweight water retaining material prepared from sludge incineration slag, characterized by, Prepared according to any one of claims 1-3.

5. The lightweight water retaining material produced from sludge incineration ash according to claim 4, characterized by, The lightweight water retaining material is a ceramic ball with a bulk density of 400-500 kg / cm 3 , a cylinder pressure strength of 1.5-2.5 MPa, and a water absorption of 30-50%.

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