A method for preparing a road base material using incineration slag and contaminated sludge

Abstract

This invention discloses a method for preparing road base materials using incinerator slag and contaminated sludge. The method includes the following steps: wet-processing and chemically modifying the incinerator slag to obtain activated incinerator slag; treating solid-phase sludge using low-temperature plasma to obtain pretreated sludge; uniformly mixing the activated incinerator slag and pretreated sludge to obtain a mixed raw material; adding a mineralizing agent to the mixed raw material and mixing it uniformly, then adding water to obtain a reactive wet material; subjecting the reactive wet material to a hydrothermal reaction to obtain a mineralized material; and uniformly mixing the mineralized material with a water glass solution to obtain the road base material. This invention promotes the reaction of heavy metals in incinerator slag and contaminated sludge with the mineralizing agent under hydrothermal treatment conditions, solidifying and stabilizing them, effectively reducing the long-term leaching risk of heavy metals in the roadbed and their migration into the environment. Simultaneously, the hydrothermal treatment produces a thermodynamically stable mineral phase, significantly enhancing the strength, durability, and compressive strength of the roadbed material.

Description

Technical Field

[0001] This invention relates to the field of solid waste harmless treatment and environmental protection technology, and in particular to a method for preparing road base materials using incinerator slag and polluted sludge. Background Technology

[0002] In the field of solid waste harmless treatment and environmental protection technology, the treatment of incinerator slag and contaminated sludge has always been a difficult and hot topic. As a residue from the incineration process, incinerator slag is rich in heavy metals and other harmful substances, and if not properly treated, it can easily cause secondary pollution to the ecological environment. Similarly, contaminated sludge, especially sludge from industrial wastewater treatment plants and municipal wastewater treatment plants, contains a large amount of toxic and harmful heavy metals and organic pollutants. If directly discharged or improperly treated, it will pose a serious threat to soil, water bodies, and groundwater.

[0003] Traditional methods for treating incinerator slag and contaminated sludge mainly include landfilling, solidification / stabilization, and heavy metal recovery. While landfilling is relatively inexpensive, it presents challenges such as large land occupation and high leakage risks, hindering environmental protection and sustainable development. Solidification / stabilization technologies use physical or chemical means to stabilize or encapsulate hazardous substances within materials. Although this reduces risk to some extent, under specific environmental conditions, such as acidic or reducing environments, heavy metals and other hazardous substances may still be released again, posing potential environmental risks.

[0004] In addition, existing heavy metal recovery technologies, such as thermal treatment, electrochemical methods, chemical extraction and biotechnology, although theoretically capable of recovering and utilizing heavy metals, generally face problems such as high cost, high energy consumption and complex processes. In practical applications, they are inefficient and may bring the risk of secondary pollution, which limits their widespread application. Summary of the Invention

[0005] In view of the technical problems existing in the prior art, the present invention provides an efficient and environmentally friendly method for treating incinerator slag and polluted sludge, which can achieve both harmless treatment and effective recycling of resources.

[0006] A method for preparing road base material using incinerator slag and contaminated sludge includes the following steps:

[0007] S1: Activated incinerator slag, obtained by wet conditioning and chemical modification of incinerator slag;

[0008] S2: Pre-treat contaminated sludge, separate the contaminated sludge into solid and liquid phases to obtain solid phase sludge, and subject the solid phase sludge to low-temperature plasma treatment to obtain pre-treated sludge;

[0009] S3: Prepare mixed raw materials by uniformly mixing the activated incinerator slag and the pretreated sludge to obtain mixed raw materials;

[0010] S4: Prepare the wet reaction material by adding a mineralizing agent to the mixed raw materials and mixing evenly to obtain the dry reaction material, and then adding water to the dry reaction material to obtain the wet reaction material;

[0011] S5: Preparation of mineralized materials by hydrothermal reaction: The wet reaction material is placed in a hydrothermal reactor for hydrothermal reaction to obtain mineralized materials;

[0012] S6: Prepare road base material by mixing the mineralized material with water glass solution evenly to obtain road base material.

[0013] Furthermore, the particle size of the incinerator slag is ≤200 µm.

[0014] Furthermore, the chemical modification treatment method involves mixing the wet-processed incinerator slag with a water glass solution and allowing it to stand for 4-12 hours. The wet-processing method involves adding 10-15% of the dry weight of water to the incinerator slag. The water glass solution has a modulus of 2.0-3.3, a concentration of 20-30%, and is added in an amount 5-10 times the mass of the wet-processed incinerator slag.

[0015] Furthermore, the solid-liquid separation is carried out using a centrifugal separation device with a rotation speed of 3000~4500 rpm / min and a time of 10~20 min, and the water content of the solid sludge is 20~30%.

[0016] Furthermore, the low-temperature plasma treatment temperature is 20~30℃, the discharge voltage is 25~35 kV, and the treatment time is 30~45 min.

[0017] Furthermore, the activated incinerator slag in the mixed raw materials has a mass fraction of 60-80%, and the pretreated sludge has a mass fraction of 20-40%.

[0018] Furthermore, the mineralizing agent is composed of calcium silicate and calcium hydrogen phosphate, with mass fractions of 70-80% and 20-30%, respectively.

[0019] Furthermore, the amount of mineralizer added to the reaction dry material is 5-15% of the mass of the mixed raw materials, and the amount of water added to the reaction dry material is 32-42% of the weight of the reaction dry material.

[0020] Furthermore, the hydrothermal reaction temperature is 180~250℃, the reaction pressure is 3~5 MPa, and the reaction time is 6~12h.

[0021] Furthermore, the modulus of the water glass solution is 2.0~2.5, the concentration is 40~50%, and the mass fractions of the mineralizing material and the water glass solution are 80~90% and 10~20%, respectively.

[0022] In summary, the present invention has the following beneficial effects:

[0023] First, this invention employs a sealed reactor for hydrothermal mineralization, which effectively inhibits the generation of harmful particulate matter, thereby significantly reducing environmental pollution during material processing. Simultaneously, this process promotes the formation of thermodynamically stable mineral phases, greatly enhancing the strength, durability, and compressive strength of the road base material.

[0024] Secondly, this invention promotes the chemical reaction between heavy metals and mineralizing agents, forming stable compounds that significantly reduce the migration of heavy metals and enhance the stability of the solidified body after treatment. This method solves the environmental pollution problems caused by incinerator slag and contaminated sludge, effectively avoids the risk of secondary pollution, and significantly improves the engineering performance of materials, achieving the harmless treatment and efficient resource utilization of solid waste. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates a method for preparing road base materials using incinerator slag and contaminated sludge, as provided by this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] A method for preparing road base materials using incinerator slag and contaminated sludge, such as Figure 1 As shown, it includes the following steps:

[0029] S1: To prepare activated incinerator slag, the incinerator slag is screened, wet-processed, chemically modified, stirred, dried and ground to obtain activated incinerator slag.

[0030] S2: Pre-treated sludge is prepared by separating the polluted sludge into solid and liquid phases using a centrifugal separator. The solid sludge is then placed in a low-temperature plasma reactor for treatment. After plasma treatment, the sludge is dried and ground to obtain pre-treated sludge.

[0031] S3: Prepare mixed raw materials by mixing activated incinerator slag and pretreated sludge in a certain proportion to obtain mixed raw materials;

[0032] S4: Prepare the wet reaction material by mixing calcium silicate powder and calcium hydrogen phosphate powder in a certain proportion to obtain a mineralizer. Mix the mixed raw materials and the mineralizer evenly to obtain the dry reaction material, and add an appropriate amount of water to obtain the wet reaction material.

[0033] S5: Hydrothermal reaction to prepare mineralized materials. The wet reaction material is placed in a hydrothermal reactor, and the appropriate reaction temperature, reaction pressure and processing time are controlled to carry out the hydrothermal reaction. The product is then dried and ground to obtain the mineralized material.

[0034] S6: Prepare road base material by mixing the mineralized material with water glass solution in a certain proportion to prepare road base material.

[0035] This solution utilizes hydrothermal reactions to treat pollutants such as incinerator slag and contaminated sludge, promoting the formation of thermodynamically stable mineral phases. This significantly enhances the strength, durability, and compressive strength of road base materials. Furthermore, by promoting the chemical reaction between heavy metals and mineralizing agents in the pollutants during the process, stable compounds are formed, significantly reducing the migration of heavy metals and enhancing the stability of the solidified body after treatment. This solution effectively addresses the environmental pollution problems caused by incinerator slag and contaminated sludge, mitigating the risk of secondary pollution, and significantly improving the engineering performance of materials, achieving the harmless treatment and efficient resource utilization of solid waste.

[0036] Furthermore, the method for preparing activated incinerator slag in step S1 includes:

[0037] The screening method involves screening the incinerator slag to remove particles and impurities with a particle size greater than 200 µm, thereby obtaining fine-particle incinerator slag with uniform particle size.

[0038] The wet conditioning method involves adding 10-15% water by dry weight to the incinerator slag to homogenize its physicochemical properties and reduce dust generation.

[0039] The chemical modification method involves mixing incinerator slag with water glass solution and allowing it to stand for 4-12 hours. The water glass solution has a modulus of 2.0-3.3, a concentration of 20-30%, and is added in an amount 5-10 times the mass of the incinerator slag. The water glass solution can react with the metal oxides in the incinerator slag to generate silicate mineral phases, thereby activating the potential active substances in the incinerator slag and enhancing its reactivity.

[0040] The stirring method is mechanical stirring, the drying conditions are drying at 100℃ for 24 h, and the grinding time is 8~15 min. The above operations can increase the specific surface area of ​​the material, enhance its binding ability with other components in the subsequent reaction process, and thus promote the mineralization reaction.

[0041] Furthermore, the method for preparing pretreated sludge in step S2 includes:

[0042] The solid-liquid separation is carried out using a centrifugal separation device with a rotation speed of 3000~4500 rpm / min and a time of 10~20 min. The water content of the solid sludge is 20~30%.

[0043] A low-temperature plasma reactor is used to treat the solid sludge. The working chamber volume of the low-temperature plasma reactor is 10-20 L. It is equipped with a cooling water circulation system. The treatment temperature of the low-temperature plasma is controlled at 20-30℃. Since the operating temperature range of the low-temperature plasma reactor is hundreds to thousands of degrees Celsius, and the electron temperature is thousands to tens of thousands of degrees Celsius, the contact time between the plasma and the treated material is several microseconds to hundreds of microseconds. The treatment temperature of the low-temperature plasma refers to the external ambient temperature, maintained within the range of room temperature (approximately 20-30℃) to ensure the stability of the low-temperature environment. The reactor uses a bipolar pulse power supply with a working frequency controlled at 25-35 kHz and a discharge voltage of 25-35 kV to ensure stable plasma generation and effectively control the energy coupling efficiency during the reaction process to improve plasma generation efficiency. A high-efficiency ceramic dielectric barrier layer is installed inside the reactor to further optimize plasma generation. The treatment time for the solid sludge using this low-temperature plasma reactor is 30-45 minutes. Under the action of low-temperature plasma, organic pollutants in sludge are decomposed through physical bombardment and chemical reaction. At the same time, ultraviolet photons in low-temperature plasma effectively inactivate pathogenic microorganisms in sludge and reduce the biotoxicity of sludge.

[0044] The sludge treated by the low-temperature plasma reactor is placed in a drying device and dried at 100°C for 24 hours. Then, the dried sludge is ground for 10-15 minutes using a grinding device.

[0045] Furthermore, the method for preparing the mixed raw materials in step S3 includes:

[0046] The activated incinerator slag in the mixed raw materials has a mass fraction of 60-80%, and the pretreated sludge has a mass fraction of 20-30%.

[0047] Further, the method for preparing the wet reaction mixture in step S4 includes:

[0048] The mineralizing agent is composed of calcium silicate and dicalcium phosphate, with mass fractions of 70-80% and 20-30%, respectively. Calcium silicate, under hydrothermal reaction conditions, can react with silicon and calcium components in the material to form stable silicate mineral phases such as tobermorite, significantly improving the mechanical properties and durability of the mineralized product. dicalcium phosphate can react with metal ions in the material to form insoluble phosphate precipitates, fixing harmful heavy metals, further improving the chemical stability of the material, and reducing the risk of leaching harmful substances.

[0049] The amount of mineralizer added to the reaction dry material is 5-15% of the mass of the mixed raw materials.

[0050] The amount of water added to the reaction dry material is 32-42% of the weight of the reaction dry material, ensuring that the water is in full contact with the reaction dry material.

[0051] Furthermore, the method for preparing mineralized materials via hydrothermal reaction in step S5 includes:

[0052] The hydrothermal reactor is equipped with an adjustable-speed stirring device to ensure uniform distribution of materials under high temperature and high pressure, preventing agglomeration and insufficient local reaction. The reactor employs a double-jacket design; the outer jacket is equipped with an electric or steam heating system to control the reaction temperature, with a temperature sensor connected to the control system for real-time monitoring and adjustment. The inner jacket is a high-pressure-resistant structure, with pressure monitored by a pressure sensor and maintained by heating and the vapor pressure of the liquid within the reactor. This method utilizes a sealed reactor for hydrothermal mineralization, effectively suppressing the generation of harmful particulate matter and significantly reducing environmental pollution during material processing.

[0053] The hydrothermal reactor controls the reaction temperature at 180~250℃ and maintains the pressure at 3~5 MPa. The entire hydrothermal reaction process lasts for 6~12 hours to ensure that the harmful substances in the incinerator slag and polluted sludge fully react with the mineralizing agent to generate thermodynamically stable silicate and phosphate mineral phases.

[0054] The hydrothermal reaction products are gradually cooled to room temperature through the cooling system of the hydrothermal reactor, and then the internal pressure is slowly released. Although the hydrothermal reactor operates under high temperature conditions, the products after the reaction may still retain a certain amount of moisture because the reaction is carried out in a high-pressure environment. The reaction products are taken out and dried at 80~100℃ for 24 h to completely remove residual moisture, and then ground for 8~12 min.

[0055] Furthermore, the method for preparing the road base material in step S6 includes:

[0056] The water glass solution has a modulus of 2.0 to 2.5 and a concentration of 40 to 50%, and the mineralizing material and the water glass solution have mass fractions of 80 to 90% and 10 to 20%, respectively.

[0057] The specific implementation process involves using the road base material prepared according to this invention for roadbed compaction, which includes key steps such as roadbed compaction and maintenance.

[0058] The compaction method employs a progressive compaction approach, using a steel-drum roller with a weight range of 18–22 t to compact the mixed material in layers, with each layer thickness controlled within 150 mm, until the designed compaction degree is achieved. During compaction, two passes of low-speed static compaction are first performed at a speed of approximately 1.0–1.4 km / h to eliminate initial voids in the material and achieve preliminary density and uniformity. Next, two passes of medium-speed static compaction are performed at a speed of 1.8–2.2 km / h to further improve the density and uniformity of the material. Then, two passes of strong vibration compaction are performed at a speed of 2.5–3.0 km / h, with an amplitude controlled at 1.5–2.0 mm and a frequency controlled at 30–35 Hz. The larger amplitude and higher frequency optimize particle arrangement and reduce internal voids. Finally, two passes of weak vibration compaction are performed at a speed of 2.3–2.7 km / h, with an amplitude controlled at 0.8–1.2 mm and a frequency controlled at 20–25 Hz. The process involves applying a static pressure at approximately 2.0 to 2.4 km / h to alleviate stress concentration that may occur after strong vibrations and enhance the overall stability of the material. Finally, a static pressure is applied at approximately 2.0 to 2.4 km / h to smooth the surface, further improving its density and smoothness. Through the synergistic effect of these steps, the overall density, uniformity, and stability of the material are ensured.

[0059] The curing method is wet curing, with a relative humidity of no less than 90% during the curing process. The curing time is adjusted according to seasonal temperature changes and ranges from 7 to 14 days to ensure the full hydration reaction of the material.

[0060] Example 1

[0061] This embodiment provides a method for preparing road base material using incinerator slag and contaminated sludge, including the following steps:

[0062] S1: The incinerator slag is taken from the incineration residue of a municipal solid waste incineration plant and mainly contains the heavy metals lead (Pb) and cadmium (Cd). These heavy metals are enriched in the slag, posing potential environmental pollution and biotoxicity risks.

[0063] Incinerator slag with a particle size of less than 200 µm was mixed with 12% water by dry weight and conditioned to a homogeneous state. Then, the conditioned slag was mixed with 8% water glass solution by weight of the slag, wherein the water glass had a modulus of 2.5 and a concentration of 25%. The mixture was thoroughly stirred and allowed to stand for 10 h, then dried, and the resulting material was ground for 10 min to obtain activated incinerator slag.

[0064] S2: The contaminated sludge was taken from the wastewater treatment system of an electroplating plant, and this sludge poses a high risk of environmental pollution. The plating solution used in the electroplating process contains heavy metals chromium (Cr), nickel (Ni), and zinc (Zn). The accumulation of these heavy metals in the environment beyond the permitted levels may cause sensitization, toxicity, and even carcinogenic risks to ecosystems and organisms.

[0065] Solid sludge with a water content of approximately 25%, obtained by centrifugation, was placed in a low-temperature plasma reactor for treatment. The reactor temperature was controlled at 25±2℃, the operating frequency was set to 30 kHz, the discharge voltage was 30 kV, and the treatment time was 40 min. Subsequently, the plasma-treated sludge was dried and ground to obtain pretreated sludge.

[0066] S3: Mix the activated incinerator slag and pretreated sludge in a certain proportion to form a mixed raw material, wherein the activated incinerator slag has a mass fraction of 60% and the pretreated sludge has a mass fraction of 40%.

[0067] S4: Mix calcium silicate powder and dicalcium phosphate powder evenly in a certain proportion to form a mineralizer, wherein the mass fraction of calcium silicate powder is 70% and the mass fraction of dicalcium phosphate powder is 30%. Add 8% (by mass) of the mineralizer to the mixed raw materials and mix thoroughly to obtain the dry reaction mixture. Subsequently, add 35% (by mass) of water to the dry reaction mixture and continue mixing evenly to obtain the wet reaction mixture.

[0068] S5: The wet reaction material is placed under hydrothermal reaction conditions, with the reaction temperature controlled at 200℃, the reaction pressure set at 4 MPa, and the treatment time at 10 h. Subsequently, the product obtained by the hydrothermal reaction is dried and ground for 10 min to obtain the mineralized material.

[0069] S6: Mix the mineralized material with a water glass solution with a modulus of 2.5 and a concentration of 40% in a certain proportion, wherein the mass fraction of the mineralized material is 80% and the mass fraction of the water glass solution is 20%.

[0070] The designed road base area is 50 m². 2 The top surface is 2.5 m wide and 25 cm thick, and is paved in two layers using a 20-ton steel wheel roller. The compaction process includes the following steps: First, two passes of low-speed static compaction are performed at a speed of approximately 1.2 km / h; then, two passes of medium-speed static compaction are performed at a speed of 2.0 km / h; next, two passes of strong vibratory compaction are performed at a speed of 2.8 km / h, with an amplitude controlled at 1.8 mm and a frequency controlled at 32 Hz; then, two passes of weak vibratory compaction are performed at a speed of 2.5 km / h, with an amplitude controlled at 1.0 mm and a frequency controlled at 22 Hz; finally, one pass of static compaction is performed at a speed of approximately 2.2 km / h to finish the surface.

[0071] The maintenance method involved covering the burlap sacks with moisture-retaining materials, ensuring an overlap of at least 10cm between adjacent sacks, and then covering the sacks with a layer of soil. The sacks were then completely covered with soil, and water was sprayed regularly to maintain a relative humidity of 95% for both the sacks and the soil. After 7 days of maintenance, samples of the obtained road base material were taken for testing.

[0072] Example 2

[0073] The only difference from Example 1 is that in step S3 of this example, the mass fractions of activated slag and pretreated sludge in the mixed raw materials are 80% and 20%, respectively.

[0074] Example 3

[0075] The only difference from Example 1 is that in step S4 of this example, the amount of mineralizer added accounts for 12% of the mass of the mixed raw materials.

[0076] Comparative Example 1

[0077] The only difference from Example 1 is that in step S5 of this comparative example, the reaction temperature is set to 25°C (room temperature) and the reaction pressure is set to 101 kPa (atmospheric pressure), that is, the reaction of the wet material is carried out under normal temperature and pressure conditions.

[0078] Experimental Results and Analysis

[0079] The CBR bearing capacity of the undisturbed samples taken in each embodiment was tested according to the "Specifications for Design of Highway Subgrade" (JTG D30-2015), the unconfined compressive strength was tested according to the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), the resistance to wet-dry cycles and freeze-thaw cycles was tested according to the "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG E51-2009), and the leaching toxicity of solid waste was tested according to the "Leaching Toxicity of Solid Waste - Sulfuric Acid and Nitric Acid Method" (HJ / T299-2007). The results are shown in Table 1.

[0080] Table 1. Overview of the properties of road base materials prepared in each embodiment.

[0081]

[0082] According to the "Specifications for Highway Subgrade Design" (JTG D30-2015), the CBR (Carrying Ratio) requirement for subbase materials is generally no less than 30%, while that for upper base materials is no less than 50%. Specifically, the CBR of highway base materials should reach or exceed 60% to ensure sufficient load-bearing capacity for high-speed traffic. The test results in this embodiment show CBRs of 60%, 65%, and 62%, respectively, all conforming to relevant specifications and suitable for road structures subjected to significant loads.

[0083] Unconfined compressive strength is an important indicator for evaluating the load-bearing capacity of materials under compression. The unconfined compressive strength requirement for the subbase is usually not less than 1.5 MPa, while that for the upper base is not less than 2.5 MPa. However, in this embodiment of the invention, the tested unconfined compressive strengths were 4.0 MPa, 4.2 MPa, and 4.1 MPa, respectively, which far exceed the strength requirements of the subbase and upper base.

[0084] According to the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG E51-2009), the strength loss rate of the material after 10 wet-dry cycles should not exceed 15%; after 5 freeze-thaw cycles, the strength loss rate should not exceed 5%, to ensure that the material can maintain structural stability and durability under conditions of humidity and temperature changes. Tests showed that the road base material in this embodiment exhibited strength loss rates of 8%, 6%, and 7% after 10 wet-dry cycles, respectively, far below the standard requirements, demonstrating excellent resistance to wet-dry cycles and making it suitable for areas with heavy rainfall or frequent humidity fluctuations.

[0085] Furthermore, the strength loss rates of the materials in the embodiments of the present invention after five freeze-thaw cycles were 1.5%, 1%, and 1.2%, respectively, significantly better than the standard requirements, demonstrating extremely strong freeze-thaw resistance. They are suitable for cold regions and can maintain structural and performance stability in long-term freeze-thaw environments. Analysis of the mechanical and durability properties of the road base material in the embodiments of the present invention shows that the road base material of the present invention is suitable for various road base structures, including high-grade road bases for highways and general roads, which have high requirements for load-bearing capacity and long-term durability.

[0086] According to the "Identification Standard for Hazardous Waste - Leaching Toxicity Identification" (GB 5085.3-2007), the leaching toxicity limits for heavy metals are as follows: lead (Pb) is 5.0 mg / L, cadmium (Cd) is 1.0 mg / L, and hexavalent chromium (Cr) is... 6+ The limits for heavy metal leaching are 5.0 mg / L for nickel (Ni) and 100 mg / L for zinc (Zn). The leaching data for heavy metals obtained in the embodiments of this invention are all below the limits specified in the standards. Therefore, the embodiments of this invention are all within safe limits in terms of heavy metal leaching toxicity and comply with relevant environmental regulations.

[0087] In summary, the road base materials in all embodiments provided by this invention exhibit significant advantages in mechanical properties, specifically high CBR load-bearing capacity and unconfined compressive strength, ensuring superior load-bearing capacity and structural stability under various load conditions. Regarding durability, the material demonstrates excellent resistance to wet-dry cycles and freeze-thaw cycles, maintaining stable performance under harsh climatic conditions and significantly reducing material degradation and damage caused by environmental changes. Simultaneously, the road base material of this invention possesses excellent heavy metal stabilization effects, effectively solidifying heavy metals and meeting relevant environmental protection standards, thereby effectively reducing the potential pollution risks to the surrounding ecological environment.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing road base material using incinerator slag and contaminated sludge, characterized in that, Includes the following steps: S1: Activated incinerator slag. The incinerator slag is subjected to wet conditioning and chemical modification to obtain activated incinerator slag. The wet conditioning method is to add 10-15% of the dry weight of water to the incinerator slag. The chemical modification method is to mix the wet-conditioned incinerator slag with water glass solution evenly and let it stand for 4-12 hours. S2: Pre-treat contaminated sludge, separate the contaminated sludge into solid and liquid phases to obtain solid phase sludge, and subject the solid phase sludge to low-temperature plasma treatment to obtain pre-treated sludge; S3: Prepare mixed raw materials by mixing the activated incinerator slag and the pretreated sludge evenly to obtain mixed raw materials; S4: Prepare the wet reaction material by adding a mineralizing agent to the mixed raw materials and mixing evenly to obtain a dry reaction material, and adding water to the dry reaction material to obtain the wet reaction material. The mineralizing agent is composed of calcium silicate and calcium hydrogen phosphate. S5: Preparation of mineralized materials by hydrothermal reaction: The wet reaction material is placed in a hydrothermal reactor for hydrothermal reaction to obtain mineralized materials; S6: Prepare road base material by mixing the mineralized material with water glass solution evenly to obtain road base material.

2. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The particle size of the incinerator slag is ≤200 µm.

3. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The water glass solution in step S1 has a modulus of 2.0 to 3.3, a concentration of 20 to 30%, and is added in an amount that is 5 to 10 times the mass of the wet-processed incinerator slag.

4. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The solid-liquid separation is carried out using a centrifugal separation device with a rotation speed of 3000~4500 rpm / min and a time of 10~20 min. The water content of the solid sludge is 20~30%.

5. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The low-temperature plasma treatment temperature is 20~30℃, the discharge voltage is 25~35 kV, and the treatment time is 30~45 min.

6. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The activated incinerator slag in the mixed raw materials has a mass fraction of 60-80%, and the pretreated sludge has a mass fraction of 20-40%.

7. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The mass fractions of calcium silicate and calcium hydrogen phosphate are 70-80% and 20-30%, respectively.

8. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The amount of mineralizer added to the reaction dry material is 5-15% of the mass of the mixed raw materials, and the amount of water added to the reaction dry material is 32-42% of the weight of the reaction dry material.

9. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The hydrothermal reaction temperature is 180~250℃, the reaction pressure is 3~5 MPa, and the reaction time is 6~12 h.

10. The method for preparing road base material using incinerator slag and contaminated sludge according to claim 1, characterized in that, The water glass solution in step S6 has a modulus of 2.0 to 2.5 and a concentration of 40 to 50%, and the mineralizing material and the water glass solution have mass fractions of 80 to 90% and 10 to 20%, respectively.

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