A household garbage incineration fly ash resource treatment system and treatment process

Abstract

This invention discloses a system and process for the resource recovery of fly ash from municipal solid waste incineration. The system includes a feeding buffer unit, a slurry-washing unit, a low-temperature detoxification unit, a water treatment unit, and a tailings resource recovery unit. The slurry-washing unit includes a primary washing and dewatering device and a secondary washing and dewatering device. The filtrate from the primary washing and dewatering device is sent to the water treatment unit, and the solid ash from the secondary washing and dewatering device is fed into the preheating tank of the low-temperature detoxification unit. The low-temperature detoxification unit includes a preheating tank, a detoxification reactor, an energy recovery component, and a dewatering device arranged sequentially. The steam exhaust port of the detoxification reactor is connected to the preheating tank. The filtrate outlet of the dewatering device is connected to the preheating tank, and the ash outlet of the dewatering device is connected to the tailings resource recovery unit. The solid material outlet of the water treatment unit is connected to the preheating tank. This invention systematically solves the problem of synergistic treatment of chlorides, heavy metals, and dioxins in fly ash, and simultaneously achieves the resource recovery of fly ash and secondary pollutants.

Description

Technical Field

[0001] This invention relates to the field of waste incineration fly ash treatment technology, specifically to a resource utilization treatment system and process for municipal solid waste incineration fly ash. Background Technology

[0002] Fly ash is a secondary pollutant generated during the incineration of municipal solid waste. It contains high concentrations of soluble chloride salts (such as NaCl and KCl), a certain amount of heavy metals (such as Pb, Cd, Zn, and Cr), and trace amounts of persistent organic pollutants (such as dioxins). It is classified as hazardous waste, and its treatment and disposal are becoming increasingly prominent issues that urgently need to be effectively addressed.

[0003] The traditional method for treating fly ash is primarily the solidification and stabilization-safe landfill approach. While this method offers advantages such as ease of operation, mature technology, and wide applicability, it essentially involves the transfer and sequestration of pollutants. This not only permanently occupies land resources but also fails to effectively decompose the highly toxic dioxins and other persistent organic pollutants in fly ash, posing a significant risk of environmental leakage. Furthermore, this technology cannot recover and reuse valuable resources from fly ash, contradicting the sustainable development concepts of "zero-waste city" construction and a circular economy.

[0004] To address this predicament, resource-oriented fly ash disposal technologies have been widely explored in recent years, such as cement kiln co-processing, high-temperature sintering / melting to prepare ceramsite or glass, and plasma gasification melting. These technologies attempt to stabilize heavy metals and degrade dioxins through high temperatures or chemical means, transforming fly ash into building materials and other products. However, they all face significant bottlenecks in industrial-scale application: cement kiln co-processing is constrained by geographical and market limitations and poses a potential risk to cement performance; high-temperature sintering / melting technology consumes enormous amounts of energy, and the market competitiveness and acceptance of the resulting building materials remain to be verified; and technologies such as plasma melting are difficult to apply on a large scale due to extremely high investment and operating costs.

[0005] Therefore, under the policy guidance of "zero-waste city" construction and resource recycling, the industry urgently needs to develop a method that can economically and efficiently solve the problem of removing chloride, heavy metals and dioxins from fly ash simultaneously, while ensuring the resource utilization of the final products, so as to achieve zero landfill, harmlessness and resource utilization of fly ash.

[0006] The key to fly ash resource utilization lies in how to efficiently and with low energy consumption transform and degrade various heavy metals and dioxins in dechlorinated fly ash, converting it into general solid waste. Hydrothermal treatment or wet catalytic oxidation for heavy metal stabilization and dioxin transformation and degradation is a relatively ideal solution. This type of technology, operating in a relatively mild medium-low temperature hydrothermal environment (generally 150℃~350℃), utilizes heavy metal and / or dioxin treatment agents to reduce the toxicity of fly ash. The products meet the treatment requirements for general solid waste, demonstrating significant energy-saving and consumption-reducing advantages.

[0007] Existing harmless and resource-based technologies still have shortcomings. First, pretreatment efficiency (mainly water washing and dechlorination) is low. Traditional water washing equipment relies on natural diffusion or stirring, resulting in low solid-liquid mass transfer efficiency, leading to large water consumption, incomplete dechlorination, and long reaction times, significantly increasing water treatment costs and limiting system capacity. Second, detoxification unit operating costs and energy consumption are high: mainstream detoxification technologies (such as high-temperature sintering / melting, low-temperature thermal decomposition, hydrothermal technology, etc.) generally rely on high-temperature and high-pressure conditions or require the addition of multiple chemical agents, resulting in huge system energy consumption. Furthermore, the cost of chemicals and the equipment's temperature and pressure resistance requirements jointly drive up operating costs. Third, system reliability is insufficient. Some solutions suffer from severe equipment corrosion and complex operation, leading to high system failure rates, frequent maintenance, and poor long-term stability and economy. Fourth, the technology and economics cannot form a closed loop: most solutions focus on the "detoxification" stage, lacking a complete design for the final treatment of high-salinity wastewater and the high-value utilization of harmless fly ash, resulting in a broken technology chain, failing to form a sustainable economic closed loop, and posing a risk of secondary pollution.

[0008] Existing reaction vessels or stirred tanks under low-temperature hydrothermal / wet catalytic oxidation conditions are pressure vessels operating in a batch feed manner. To improve the processing capacity of the batch reactor and recover heat, current solutions involve adding multiple pretreatment or preheating tanks and post-treatment tanks to perform multiple stepped heat exchanges between the current batch of feed and the previous batch, thereby reducing the residence time of the material in the reaction vessel and recovering some energy. However, this solution inevitably leads to a series of problems such as an increase in the number of devices and a complex material transfer path.

[0009] Materials processed using low-temperature hydrothermal or wet catalytic oxidation typically have a high moisture content, generally above 75%, otherwise homogeneous mixing and sufficient heating for reaction will be difficult to achieve. Existing solutions with high material moisture content limit the processing capacity of the reaction vessel and significantly increase energy consumption; alternatively, more powerful stirring equipment or faster rotation speeds may be used, leading to increased wear, higher energy consumption, and a rapid shortening of equipment lifespan.

[0010] Low-temperature hydrothermal or wet catalytic oxidation reactions involve high-temperature materials. After the reaction, the materials need to be cooled before they can be discharged and transported to the next process stage. Existing technologies can quickly reduce the temperature to around 120°C by utilizing the steam depressurization within the reaction tank. However, the high-temperature, high-solids materials in the reaction tank have a certain viscosity, making it difficult to achieve stable long-term emptying using conventional screw pump sets. This can easily lead to problems such as stator softening, rotor jamming, severe wear, and material blockage inside the tank and in the pipelines.

[0011] After each batch of hydrothermal reaction, the material and steam in the tank still carry a large amount of heat that can be recovered and reused. Generally, the steam is depressurized to preheat the next batch of material, recovering some of the heat. After the material cools down to below 120°C, the steam heat exchange capacity decreases significantly. However, at this point, the material temperature and solids content are too high to be discharged immediately. Generally, it needs to be cooled naturally or by adding about 20% of the total material in the tank with cold water to cool it down to about 100°C before it can be stably transported to the next process stage. The above cooling methods will greatly prolong the process residence time, limit the equipment's processing capacity, and increase process water consumption. In addition, the low-quality waste heat generated by intermittent discharge has little recovery value and is difficult to meet the needs of upstream or downstream processes, easily leading to energy waste. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a simple, easy-to-operate, and effective system and process for the resource utilization of fly ash from municipal solid waste incineration, which is beneficial to improving the quality of fly ash treatment, in order to address the shortcomings of the existing technology.

[0013] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A system for the resource utilization of fly ash from municipal solid waste incineration includes: a feeding buffer unit, a slurry-washing unit, a low-temperature detoxification unit, a water treatment unit, and a tailings resource utilization unit; The pulping-washing unit includes a pulping tank, a primary washing tank, a primary dewatering device, a primary crushing device, a secondary washing tank, a secondary dewatering device, and a secondary crushing device arranged sequentially. The low-temperature detoxification unit includes a preheating tank, a detoxification reaction vessel, an energy recovery component, and a dehydration device arranged in sequence. The feed buffer unit is connected to the slurry tank; the filtrate outlet of the primary dewatering device is connected to the water treatment unit; the filtrate outlet of the secondary dewatering device is connected to the primary washing tank; and the ash outlet of the secondary crushing device is connected to the preheating tank. The steam exhaust port of the detoxification reactor is connected to the preheating tank; the filtrate outlet of the dewatering equipment is connected to the preheating tank; and the solid material outlet of the dewatering equipment is connected to the tailings resource utilization unit. The solid material outlet of the water treatment unit is connected to the preheating tank, and the condensate outlet of the water treatment unit is connected to the secondary washing tank.

[0014] As a further improvement of the present invention, the water treatment unit includes a gravity and hardness removal reaction tank, an ultrafiltration device, a nanofiltration device, and an evaporation and salt separation device arranged in sequence; the solid material outlet of the ultrafiltration device is connected to a preheating tank, the concentrated phase material outlet of the nanofiltration device is connected to a preheating tank, and the condensate outlet of the evaporation and salt separation device is connected to a secondary washing tank.

[0015] As a further improvement of the present invention, the energy recovery component is a cascaded heat recovery system consisting of multiple heat exchangers and cooling towers; the latent heat of the depressurized steam in the detoxification reactor is recovered for heating the preheating tank, and the sensible heat of the slurry in the detoxification reactor is recovered through the energy recovery component.

[0016] As a further improvement of the present invention, the slurry tank is provided with a stirring paddle, which has multiple serrated blades along the vertical direction; the inner sidewall of the slurry tank is provided with a U-shaped baffle, and the stirring paddle and the U-shaped baffle work together to form a strong shear and turbulent field.

[0017] As a further improvement of the present invention, the primary washing tank and the secondary washing tank have the same structural configuration; the primary washing tank is provided with an axial flow agitator, the axial flow agitator is provided with multiple layers of agitator impellers in the vertical direction, and each layer of agitator impellers faces the bottom of the primary washing tank; the inner sidewall of the primary washing tank is provided with multiple layers of deflection baffles in the vertical direction, and the deflection directions of adjacent layers of deflection baffles are opposite.

[0018] As a further improvement of the present invention, the bottom of the primary washing tank is provided with a discharge port, and a three-way control valve is provided on the discharge port; a forced reflux pipe is provided on the outside of the primary washing tank, the discharge end of the forced reflux pipe is connected to the upper part of the primary washing tank, a circulation pump is provided on the forced reflux pipe, the inlet end of the circulation pump is connected to one outlet of the three-way control valve through a pipe, and the other outlet of the three-way control valve is connected to the discharge pipe.

[0019] As a general technical concept, the present invention also provides a process for the resource utilization of fly ash from municipal solid waste incineration. The process employs the aforementioned municipal solid waste incineration fly ash resource utilization system to perform water washing and dechlorination, dioxin removal, and heavy metal solidification of the fly ash, including the following steps: Step S1: The fly ash produced by municipal solid waste incineration is collected from the incinerator flue and then enters the feed buffer unit; Step S2: The fly ash in the feed buffer unit is conveyed to the pulping tank for pulping treatment, and the resulting slurry is conveyed to the primary washing tank. Step S3: After the slurry is washed and dechlorinated in the primary washing tank, it is transported to the primary dewatering device. The liquid phase material produced by the primary dewatering device is transported to the water treatment unit for chloride recovery and utilization, and the solid phase material produced by the primary dewatering device is transported to the primary crushing device. Step S4: The slag produced in the primary crushing device is transported to the secondary washing tank for secondary washing and dechlorination, and the resulting slurry is transported to the secondary dewatering device. Step S5: The liquid material generated in the secondary dewatering device is recycled to the primary washing tank, and the solid material generated in the secondary dewatering device is transported to the secondary crushing device. Step S6: The slag produced in the secondary crushing device is transported to the preheating tank, where water and detoxification agents are added, and the materials are mixed and preheated. Step S7: The waste heat mixture in the preheating tank is transported to the detoxification reactor for detoxification reaction to achieve heavy metal stabilization and dioxin degradation. Step S8: After the detoxification reaction is completed, the depressurized steam in the detoxification reactor is recycled to the preheating tank to preheat the mixture. The high-temperature detoxified slurry in the detoxification reactor is transported to the energy recovery component for cooling and heat recovery. Step S9: The cooled detoxified slurry is transported to the dewatering equipment. The liquid phase material generated in the dewatering equipment is recycled to the preheating tank, and the solid phase material generated in the dewatering equipment is transported to the tailings resource utilization unit to realize the tailings disposal.

[0020] As a further improvement of the present invention, in step S6, the dosage of the detoxification agent is 3% to 10% of the mass of the original ash; the components of the detoxification agent include: iron salt, sulfite, sulfate, organic composite agent and supported transition metal catalyst; by weight, the iron salt is 20 to 40 parts, the sulfite is 10 to 25 parts, the sulfate is 15 to 30 parts, the organic composite agent is 5 to 15 parts, and the supported transition metal catalyst is 5 to 15 parts.

[0021] As a further improvement of the present invention, the organic composite agent is a composition of humic acid, sodium carboxymethyl cellulose and modified lignin, and the supported transition metal catalyst is supported on activated carbon, zeolite, titanium dioxide or γ-alumina, and loaded with at least one of copper, manganese, cerium or iron.

[0022] As a further improvement of the present invention, in step S6, the mixture is preheated to 80°C to 95°C in a preheating tank, and the moisture content of the material in the preheating tank is 70% to 80%.

[0023] As a further improvement of the present invention, in step S7, the temperature of the detoxification reaction is 160℃~180℃, the pressure is 0.6Mpa~1.0Mpa, and the time is 30~60min.

[0024] The municipal solid waste fly ash resource utilization system of the present invention can simultaneously achieve heavy metal stabilization and dioxin degradation at a relatively low temperature, mainly due to two synergistic effects: (1) chemical synergy between reagent components (reducing reaction activation energy and increasing reaction rate): the detoxification reagent constitutes a dual pathway of free radical oxidation and chemical precipitation, in which sulfite and transition metals continuously excite free radicals in subcritical water, directly attacking the C of dioxins. Cl bond, realize reduction dechlorination and ring-opening mineralization. The reaction rate constant of the free radical oxidation path is 2 to 3 orders of magnitude higher than that of the pure thermal decomposition path. Therefore, degradation can be completed without long-term heat preservation. At the same time, iron salt and sulfate rapidly react with dissolved heavy metal ions to form insoluble sulfate and ferrate precipitates. Organic composite agent acts as an electron donor to accelerate the cycle and assists in dispersing fly ash particles and increasing nucleation sites, which significantly reduces the activation energy of the reaction. The heavy metal precipitation reaction can reach equilibrium within a few minutes, which significantly shortens the time required for stabilization. (2) Process synergy between washing-detoxification system (eliminating inhibitory factors and enhancing mass transfer): The pre-forced turbulent washing reduces the chlorine content of fly ash to ≤1% at room temperature, eliminating the quenching effect of chloride ions on free radicals. At the same time, the specific surface area of ​​fly ash increases and pores are exposed after dechlorination, making it easier for detoxification agents to penetrate, reducing mass transfer resistance, improving the accessibility of heavy metals and dioxins, and further increasing the reaction rate.

[0025] Compared with the prior art, the advantages of the present invention are as follows: 1. The municipal solid waste incineration fly ash resource utilization system and process of the present invention utilizes a water treatment unit to recover and utilize chloride resources from the filtrate produced by the primary dewatering unit, and reuses the filtrate produced by the secondary dewatering unit back into the primary washing tank, reducing the consumption of fresh water. The ash residue produced by the secondary dewatering unit is crushed by a secondary crushing unit and directly transported to the preheating tank, realizing the resource utilization of materials throughout the slurry-washing process without generating additional waste. The water required in the preheating tank comes from the filtrate produced by the dewatering equipment, reducing system water consumption. The heat required for preheating the mixture in the preheating tank comes from the latent heat of steam released from the detoxification reactor and the latent heat of steam generated in the water treatment unit. The preheated mixture enters the detoxification reactor, which can quickly reach the required detoxification reaction temperature, achieving efficient recovery and utilization of heat energy, and also helping to reduce the time required for the detoxification reaction. The detoxified fly ash slurry is transported to the energy recovery component for heat recovery and utilization, and then transported to the dewatering unit for dewatering treatment. The resulting solid material is finally fed into the tailings resource utilization unit for disposal. This invention systematically solves the problem of synergistic treatment of chloride salts, heavy metals and dioxins in fly ash, and simultaneously completes the resource utilization of fly ash and secondary pollutants. It realizes the full-scale and high-value transformation of fly ash from hazardous waste to resource-based products, ensuring that no secondary waste is generated throughout the entire process and producing products with clear market value. It achieves the unity of environmental and economic benefits and provides a reliable technical path for the "zero landfill" and sustainable management of fly ash.

[0026] 2. The waste incineration fly ash resource utilization system and process of this invention significantly improves the quality of fly ash slurry washing by structurally modifying the slurry tank and washing tank. In the slurry tank, a stirring paddle with multi-layered serrated blades and a U-shaped baffle work together to form a strong shear and turbulent field, which quickly disperses fly ash clumps, avoiding "external wetness and internal dryness," and significantly improving the uniformity of slurry. It can also adapt to different ash qualities and operating conditions, solving the problem of fly ash caking at the source and providing a stable and homogeneous slurry for subsequent washing and dechlorination. In the washing tank, a "circulating reactor + high-flow circulation pump" is used to construct an external high-speed circulation loop, forming forced turbulence. Through the synergistic effect of stirring, internal guidance, and external circulation, the liquid film boundary layer on the particle surface is significantly thinned, reducing the material reaction mixing energy. This transforms the dechlorination process from diffusion-controlled to reaction-controlled, significantly shortening the washing and dechlorination time, improving dechlorination efficiency and effect, reducing water consumption, and lowering water treatment costs.

[0027] 3. The municipal solid waste incineration fly ash resource recovery system and process of the present invention adopts a two-stage cascade recovery design of "latent heat of steam + sensible heat of slurry" in the detoxification reactor: the first stage recovers depressurized steam for preheating tank heating to achieve preheating of the mixed materials; the second stage recovers the sensible heat of the slurry through a heat exchanger in the energy recovery component. The cooling water after heat exchange can be reused in the slurry-washing unit, and a cooling tower is configured in the energy recovery component to achieve thermal balance interlock control. It can be interlocked with the regulating valve through sensors to achieve synergistic optimization of heat recovery and system stability. Both the latent heat of steam and the sensible heat of slurry are efficiently utilized, avoiding energy waste, and also enabling the detoxified slurry to be cooled down quickly to below 60°C, shortening the batch discharge waiting time and improving the operating efficiency of the detoxification reactor; the reuse of cooling water after heat exchange reduces the need for process fresh water replenishment, and also avoids problems such as stator softening, rotor jamming, and blockage caused by high-temperature slurry directly entering the dewatering equipment.

[0028] 4. The waste incineration fly ash resource utilization treatment system and process of the present invention involves mixing and preheating the washed ash residue with a detoxification agent in a preheating tank before conveying it to a detoxification reactor for detoxification reaction. A "one-agent-two-effect" composite agent is used as the detoxification agent, with a dosage of 3% to 10% of the original ash mass. Fly ash detoxification is directly achieved through chemical precipitation and free radical oxidation pathways within a single reactor at a medium-low temperature of 160℃ to 180℃. This results in lower reaction activation energy and simultaneous heavy metal stabilization and dioxin catalytic oxidation degradation. This eliminates the complex process of separate steps and equipment for "heavy metal stabilization + dioxin degradation" in traditional processes, significantly simplifying the process, reducing reaction temperature and pressure, and decreasing investment and operating costs. Furthermore, the agent dosage is low, resulting in extremely low fly ash weight gain and volume increase rates. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the structural principle of a municipal solid waste incineration fly ash resource utilization system in a specific embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the structural principle of the slurry tank in a specific embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the structural principle of the washing tank in a specific embodiment of the present invention.

[0032] Legend: 100, Feed buffer unit; 101, Feed hopper; 200, Slurry-washing unit; 201, Slurry tank; 2011, Ash inlet; 2012, Water inlet; 2013, Observation port; 2014, Agitator; 2015, Impeller blade; 2016, U-shaped baffle; 2017, Discharge port; 2018, Jacket; 202, Primary washing tank; 2021, Feed port; 2022, Angled baffle; 2023, Axial flow agitator; 2024, Forced reflux pipe; 2025, Circulation pump; 202 6. Discharge pipe; 203. Primary dewatering device; 204. Primary crushing device; 205. Secondary washing tank; 206. Secondary dewatering device; 207. Secondary crushing device; 300. Low-temperature detoxification unit; 301. Preheating tank; 302. Detoxification reactor; 303. Energy recovery component; 304. Dewatering equipment; 400. Water treatment unit; 401. Heavy and hard removal reactor; 402. Ultrafiltration equipment; 403. Nanofiltration equipment; 404. Evaporation and salt separation equipment; 500. Tailings resource utilization unit; 501. Brick making equipment. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0034] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0036] Example 1 like Figure 1 As shown, the municipal solid waste incineration fly ash resource utilization system of the present invention includes: a feeding buffer unit 100, a slurry-washing unit 200, a low-temperature detoxification unit 300, a water treatment unit 400, and a tailings resource utilization unit 500.

[0037] The feeding buffer unit 100 includes a feeding hopper 101. The feeding hopper 101 can adopt conventional configurations in the art, including a top feed inlet, a bottom discharge outlet, an insulation and heat tracing system, and an arch-breaking device. Fly ash is collected from the incinerator flue and enters the feeding hopper 101. The fly ash has extremely low moisture content and is highly hygroscopic. To prevent caking and obstruction during temporary storage, the feeding hopper 101 is equipped with an insulation and heat tracing system to maintain a constant temperature of 60℃~80℃ inside the feeding hopper 101, preventing moisture absorption after cooling. If the heat tracing components malfunction, the internal arch-breaking device of the feeding hopper 101 can physically break up the caking. The heat source for the heat tracing system can be introduced from waste heat of the waste incineration system, heat recovery from the low-temperature detoxification unit 300, or heat recovery from the water treatment unit 400, achieving energy utilization and waste-to-waste treatment. The start and stop of the heat tracing system can be automatically controlled by a temperature sensor inside the feeding hopper 101 to reduce energy consumption. The arch-breaking device can be combined with the discharge device of the feed hopper 101, adopting a screw discharge system, and a vibration device is attached to the lower outer wall of the feed hopper 101 to solve the arch-breaking and discharge problems simultaneously with the screw discharge system.

[0038] In this embodiment, the pulping-washing unit 200 includes a pulping tank 201, a primary washing tank 202, a primary dewatering device 203, a primary crushing device 204, a secondary washing tank 205, a secondary dewatering device 206, and a secondary crushing device 207 arranged sequentially. The low-temperature detoxification unit 300 includes a preheating tank 301, a detoxification reactor 302, an energy recovery component 303, and a dewatering device 304 arranged sequentially. The feed buffer unit 100 is connected to the pulping tank 201, and the filtrate outlet of the primary dewatering device 203 is connected to the water treatment unit 400, through which chloride resources in the filtrate are recovered and utilized. The filtrate outlet of the secondary dewatering device 206 is connected to the primary washing tank 202 to achieve filtrate reuse and reduce system water consumption. The ash outlet of the secondary crushing device 207 is connected to the preheating tank 301, and the crushed dechlorinated ash is directly fed into the preheating tank 301. The steam exhaust port of the detoxification reactor 302 is connected to the preheating tank 301 to preheat the mixture in the preheating tank 301 using the depressurized steam from the detoxification reactor 302, thereby improving thermal energy utilization. The filtrate outlet of the dewatering equipment 304 is connected to the preheating tank 301 to achieve filtrate reuse, reducing water consumption and avoiding secondary waste generation. The solid material outlet of the dewatering equipment 304 is connected to the tailings resource utilization unit 500 to achieve the disposal and utilization of detoxified ash. The solid material outlet of the water treatment unit 400 is connected to the preheating tank 301 to achieve solid material disposal. The condensate outlet of the water treatment unit 400 is connected to the secondary washing tank 205 to improve water resource utilization.

[0039] In this embodiment, the solid slag after washing and dehydration enters the preheating tank 301, where water and detoxification agents are added, mixed, and preheated. It then enters the detoxification reactor 302 to achieve heavy metal stabilization and dioxin degradation. After the reaction in the detoxification reactor 302 is completed, it undergoes depressurization and cooling. The depressurized steam is used to preheat the next batch of material or for heating the feed hopper 101 and the slurry-washing unit 200. The material enters the energy recovery component 303 for cooling. The cooled material then enters the dewatering equipment 304 for dewatering. The solid phase after dewatering enters the tailings resource utilization unit 500, while the liquid phase serves as supplementary water for the preheating tank 301 or the slurry-washing unit 200. The dewatering equipment 304 can be a centrifugal dewatering machine or a plate and frame dewatering machine.

[0040] The preheating tank 301 can adopt conventional settings in the field. The top of the preheating tank 301 has a feed inlet, a dosing inlet, an observation window and a high-pressure water flushing port. The top and walls of the tank are equipped with preheating steam / hot water inlets. The preheating tank 301 is equipped with an agitator to ensure that the material is stirred evenly and does not settle during the preheating and dosing process.

[0041] The detoxification reactor 302 can be a conventional pressure vessel in the field, made of a special alloy that is alkali-resistant and chlorine-resistant; it is equipped with a multi-layer agitator; the top of the reactor is equipped with a feed inlet, a steam inlet, a pressure relief pipe, an observation window, a high-pressure water flushing port, and pressure and temperature instruments; the reactor wall is equipped with a steam inlet and a baffle plate, which can improve heating and mixing efficiency and prevent the formation of dead zones in the stirring; the bottom of the reactor is a large-diameter discharge port to prevent solid phase deposition and blockage.

[0042] In this embodiment, the energy recovery component 303 is a cascaded heat recovery system consisting of multiple heat exchangers and cooling towers; the latent heat of the depressurized steam in the detoxification reactor 302 is recovered for heating the preheating tank 301, and the sensible heat of the slurry in the detoxification reactor 302 is recovered through the energy recovery component 303.

[0043] In this embodiment, a two-stage cascade recovery design of "latent heat of steam + sensible heat of slurry" is adopted in the detoxification reactor 302: the first stage recovers depressurized steam for heating the preheating tank 301 to preheat the mixed materials; the second stage recovers the sensible heat of the slurry through the heat exchanger in the energy recovery component 303. The cooling water after heat exchange can be reused in the slurry-washing unit 200. A cooling tower is configured in the energy recovery component 303 to achieve thermal balance interlock control. It can be interlocked with the regulating valve through sensors to achieve synergistic optimization of heat recovery and system stability. Both the latent heat of steam and the sensible heat of slurry are utilized efficiently, avoiding energy waste. It also allows the detoxified slurry to be cooled down quickly to below 60°C, shortening the batch discharge waiting time and improving the operating efficiency of the detoxification reactor 302. The reuse of cooling water after heat exchange reduces the need for fresh process water replenishment and also prevents high-temperature slurry from directly entering the dewatering equipment 304, which could lead to stator softening, rotor jamming, and blockage.

[0044] like Figure 2 As shown, the slurry tank 201 adopts a vertical jacketed cylindrical structure. The upper part of the slurry tank 201 is equipped with an ash inlet 2011, a water inlet 2012, and an observation port 2013 to facilitate rapid tangential flow after material feeding. An agitator 2014 is installed inside the slurry tank 201, with three layers of serrated blades 2015 arranged vertically at the upper, middle, and bottom of the slurry tank 201. A U-shaped baffle 2016 is installed on the inner wall of the slurry tank 201. The agitator 2014 and the U-shaped baffle 2016 work together to create a strong shear and turbulent field, generating strong radial and axial flow to quickly break up fly ash clumps, ensuring slurry efficiency and uniformity. A water / steam pipe is installed inside the jacket 2018 of the slurry tank 201, allowing cooling water, hot water, or steam to be introduced according to the slurry temperature to adjust the slurry temperature. The bottom of the pulping tank 201 is the discharge port 2017. After the liquid is discharged from the bottom, it enters the primary washing tank 202.

[0045] In this embodiment, the primary washing tank 202 and the secondary washing tank 205 have the same structural configuration. For example... Figure 3 As shown, the primary washing tank 202 is provided with a feeding port 2021 at the top. The primary washing tank 202 is provided with an axial flow agitator 2023. The axial flow agitator 2023 is provided with multiple layers of agitator impellers in the vertical direction, and each layer of agitator impellers faces the bottom of the primary washing tank 202. The inner sidewall of the primary washing tank 202 is provided with three layers of deflection baffles 2022 in the vertical direction, and the deflection directions of adjacent two layers of deflection baffles 2022 are opposite.

[0046] Furthermore, the bottom of the primary washing tank 202 is provided with a discharge port, and a three-way control valve (not shown in the figure) is provided on the discharge port; a forced reflux pipe 2024 is provided on the outside of the primary washing tank 202, the discharge end of the forced reflux pipe 2024 is connected to the upper part of the primary washing tank 202, a circulation pump 2025 is provided on the forced reflux pipe 2024, the inlet end of the circulation pump 2025 is connected to one of the outlets of the three-way control valve through a pipe, and the other outlet of the three-way control valve is connected to the discharge pipe 2026, so that the slurry can be controlled to be forcibly refluxed or discharged according to process requirements.

[0047] Unlike conventional stirred washing or multi-stage washing, this embodiment uses a "circulating reactor + high-flow circulation pump" to construct an external high-speed circulation loop, with a circulation linear velocity of 0.5 m / s to 3 m / s, forming forced turbulence. A two-stage counter-current arrangement is adopted, with the liquid phase material generated in the second-stage washing being recycled to the first-stage washing. In the washing tank, through the synergistic effect of stirring, internal guidance, and external circulation, the liquid film boundary layer on the surface of fly ash particles can be significantly thinned, reducing the material reaction mixing energy and significantly improving the mass transfer coefficient of chloride ions diffusing from the solid phase surface to the liquid phase bulk. This transforms the dechlorination process from "diffusion-controlled" to "reaction-controlled," achieving a breakthrough in efficiency. Specifically, the dechlorination time is shortened to 10 min to 30 min, and the soluble chlorine content can be reduced to ≤1%; the water replenishment per ton is ≤0.5, significantly reducing the water treatment load; and the particle size after crushing is <10 mm, avoiding blockage of subsequent pipelines and the reactor.

[0048] In other embodiments, the linings of the slurry tank 201 and the washing tank can be replaced with plastic to reduce investment costs, prevent corrosion from chloride salts in fly ash, and make repair and replacement easier. The materials include, but are not limited to, fiberglass, PP, PPH, PVDF, PTFE, etc.

[0049] In this embodiment, the primary dewatering device 203 and the secondary dewatering device 206 can be plate and frame dewatering machines. Below the plate and frame dewatering machine are arranged a mesh-like structure of crushing wire ropes / nets / arch breakers / crushers, etc., to pre-crush the mud cake. The crushed material conveying equipment is a screw conveyor, which can further improve crushing efficiency and subsequent processing efficiency.

[0050] In this embodiment, both the primary crushing device 204 and the secondary crushing device 207 employ crushers. Vertical chain crushers and double-roll crushers are preferred as they can improve crushing efficiency and effectiveness.

[0051] In this embodiment, the water treatment unit 400 includes a gravity and hardness removal reaction tank 401, an ultrafiltration device 402, a nanofiltration device 403, and an evaporation and salt separation device 404 arranged sequentially. The solid material outlet of the ultrafiltration device 402 is connected to the preheating tank 301, the concentrated phase material outlet of the nanofiltration device 403 is connected to the preheating tank 301, and the condensate outlet of the evaporation and salt separation device 404 is connected to the secondary washing tank 205.

[0052] The filtrate from the primary dehydration unit 203 enters the gravity and hardening removal reaction tank 401, where gravity and hardening removal agents are added. The material discharged from the gravity and hardening removal reaction tank 401 undergoes solid-liquid separation in a high-density sedimentation tank or ultrafiltration equipment 402. The solid phase material enters the preheating tank 301, and the liquid phase material enters the nanofiltration equipment 403 to retain high-valence ions, such as sulfate and calcium, in the clarified liquid, further improving the salt separation efficiency of the evaporation and salt separation equipment 404 and reducing the production of impurities. The concentrated phase material produced by the nanofiltration equipment 403 enters the preheating tank 301, and the liquid phase material enters the evaporation and salt separation equipment 404 for evaporation and salt separation. The evaporation and salt separation equipment 404 adopts an MVR evaporation system or a multi-effect evaporation system to achieve NaCl and KCl separation. Furthermore, the ultrafiltration membrane in the ultrafiltration equipment 402 can be an external ultrafiltration membrane or an internal hollow fiber membrane.

[0053] In this embodiment, the municipal solid waste incineration fly ash resource utilization system performs water washing and dechlorination, dioxin removal, and heavy metal solidification on the fly ash, including the following steps: Step S1: The fly ash generated from the incineration of municipal solid waste is collected from the incinerator flue and then enters the feed buffer unit 100.

[0054] In step S2, the fly ash in the feed buffer unit 100 is conveyed to the slurry tank 201 for slurry processing. The resulting slurry is then conveyed to the primary washing tank 202. In the slurry tank 201, the liquid-to-solid ratio is water:raw ash = 1.5–3:1. The water intake can be adjusted according to the chlorine content in the feed fly ash. 0.3–0.5 parts of the liquid-to-solid ratio are fresh water, and the remainder is recycled water. The stirring paddle 2014 in the slurry tank 201 rotates at 50–100 rpm. The stirring rate is higher when the liquid-to-solid ratio is lower and lower when the liquid-to-solid ratio is higher.

[0055] Step S3: After primary washing and dechlorination in the primary washing tank 202, the slurry is conveyed to the primary dewatering unit 203. The liquid phase material produced by the primary dewatering unit 203 is conveyed to the water treatment unit 400 for chloride recovery and utilization, while the solid phase material produced by the primary dewatering unit 203 is conveyed to the primary crushing unit 204. Specifically, the flow rate of the circulation pump 2025 in the forced circulation system on the side of the primary washing tank 202 is 50-150 m³ / h to balance treatment efficiency and economy, and to ensure that the slurry in the primary washing tank 202 can be circulated at a linear velocity of 0.5-3 m / s, forming a strong swirling flow and a fully mixed flow field in the primary washing tank 202. The high-intensity turbulence established in the washing tank by the external circulation pump greatly enhances the solid-liquid mass transfer process, significantly shortens the water washing and dechlorination time, improves dechlorination efficiency and effect, reduces water consumption, and lowers water treatment costs. The water washing and dechlorination reaction time of the slurry in the primary washing tank 202 is 10-30 minutes; after crushing by the primary crushing device 204, the diameter (or length) of the slag is <10 mm.

[0056] In step S4, the slag produced in the primary crushing unit 204 is conveyed to the secondary washing tank 205 for secondary washing and dechlorination. The resulting slurry is then conveyed to the secondary dewatering unit 206. The operating parameters in the secondary washing tank 205 are the same as those in the primary washing tank 202.

[0057] In step S5, the liquid material generated in the secondary dewatering device 206 is recycled to the primary washing tank 202, and the solid material generated in the secondary dewatering device 206 is transported to the secondary crushing device 207; after crushing by the secondary crushing device 207, the diameter (or length) of the slag is <10 mm.

[0058] In step S6, the slag produced in the secondary crushing device 207 is conveyed to the preheating tank 301. Water and detoxification agents are then added to the preheating tank 301, and the materials are mixed and preheated. The moisture content of the materials in the preheating tank 301 is 70%–80% to ensure a balance between reaction efficiency and economy. The mixture is preheated to 80°C–95°C in the preheating tank 301 before being conveyed to the detoxification reactor 302. The stirring speed of the agitator in the preheating tank 301 is 10–60 rpm. During the heating process, the stirring speed can be appropriately increased to improve heating efficiency.

[0059] In step S7, the waste heat mixture in preheating tank 301 is transferred to detoxification reactor 302 for detoxification reaction to achieve heavy metal stabilization and dioxin degradation. Specifically, the detoxification reaction temperature is 160℃~180℃, the pressure is 0.6Mpa~1.0Mpa, and the time is 30~60min. The stirring speed in detoxification reactor 302 is 10~60 rpm. During heating, the stirring rate can be appropriately increased to improve heating efficiency, and during the detoxification reaction, the stirring rate can be appropriately decreased to prevent solid phase sedimentation.

[0060] Step S8: After the detoxification reaction is completed, the depressurized steam in the detoxification reactor 302 is recycled to the preheating tank 301 to preheat the mixture. The high-temperature detoxified slurry in the detoxification reactor 302 is transported to the energy recovery component 303 for cooling and heat recovery. The bottom outlet of the low-temperature detoxification reactor is equipped with a pull-out large-aperture mesh box to prevent the deposited solids from clogging or damaging the discharge pump. The discharge temperature of the energy recovery component 303 is below 60℃.

[0061] Step S9: The cooled, detoxified slurry is conveyed to dewatering equipment 304. The liquid phase material generated in dewatering equipment 304 is recycled to preheating tank 301, and the solid phase material generated in dewatering equipment 304 is conveyed to brick-making equipment 501 in tailings resource utilization unit 500 to achieve tailings disposal. Furthermore, the various indicators of the detoxified tailings meet the relevant standards of HJ 11134-2020, and can be used for co-resource utilization of general industrial solid waste and waste incineration slag. Slag bricks are made with a tailings blending ratio of 10%–50%, a slag blending ratio of 40%–80%, and a silicate cement blending ratio of 5%, achieving low-cost tailings disposal.

[0062] In step S6 of this embodiment, the dosage of the detoxification agent is 3% to 10% of the original ash mass; the components of the detoxification agent include: iron salt, sulfite, sulfate, organic composite agent and supported transition metal catalyst; by weight, the iron salt is 30 parts, the sulfite is 20 parts, the sulfate is 20 parts, the organic composite agent is 15 parts and the supported transition metal catalyst is 15 parts.

[0063] Furthermore, the organic composite agent is a composition of humic acid, sodium carboxymethyl cellulose, and modified lignin, and the supported transition metal catalyst is copper metal supported on activated carbon. In other embodiments, the supported transition metal may also be at least one of manganese, cerium, or iron.

[0064] In this embodiment, the roles of each component of the detoxification treatment agent include: (1) heavy metal stabilization: the iron salts and sulfates in the agent react with the Pb leached from the fly ash under subcritical hydrothermal conditions (160-180℃). 2+ Cd 2+ Zn 2+ The reaction produces insoluble sulfates (such as PbSO4) and ferrates (such as ZnFe2O4), achieving chemical precipitation stabilization. Sulfites can reduce some high-valence heavy metals (such as Cr). 6+ →Cr 3+ The process reduces the toxicity and mobility of fly ash. In a subcritical hydrothermal environment, aluminosilicate minerals in fly ash undergo partial dissolution and recrystallization, forming zeolite-like structures (such as hydrated calcium silicate and ettringite). The organic composite agents in the reagents promote the dispersion of fly ash particles and increase the nucleation sites for mineral recrystallization. The surface of the supported transition metal catalyst provides lattice defects, inducing heterogeneous nucleation of heavy metals on the catalyst surface and strengthening lattice encapsulation. Ultimately, heavy metals are fixed within a stable mineral lattice through a dual mechanism of chemical bonding and physical encapsulation.

[0065] (2) Dioxin degradation: Due to the characteristics of subcritical water environment, the dielectric constant of water decreases and the ion product exponent increases, which increases the solubility of nonpolar dioxin molecules, causing them to transfer from the solid phase to the liquid phase; at the same time, H + and OH -Increased concentration promotes free radical chain reactions. Sulfite is excited to produce sulfate radicals (SO42-). - •); A supported transition metal catalyst catalyzes the decomposition of water to generate hydroxyl radicals (·OH) via a Fenton-like reaction. An organic composite agent acts as an electron donor, accelerating the valence cycle of the transition metal and increasing the radical yield. The radicals attack the C-Cl bond of the dioxin molecule, achieving reductive dechlorination and oxidative ring-opening, ultimately mineralizing into CO2, H2O, and inorganic chloride ions.

[0066] In this embodiment, heavy metals in fly ash are stabilized mainly through two mechanisms: First, under subcritical hydrothermal conditions, a core detoxifying agent is added to chemically precipitate the heavy metals in fly ash into a chemically inert and stable form, reducing their migration and diffusion capabilities in the environment; Second, under subcritical hydrothermal conditions, mineral encapsulation and surface adsorption are used to effectively isolate heavy metals from the external environment, forming a lattice structure inside the fly ash to fix the heavy metals within the lattice structure, thus achieving heavy metal stabilization.

[0067] Within the high-pressure subcritical hydrothermal system of the detoxification reactor 302, the properties of the water medium are reconstructed by precisely controlling temperature and pressure parameters. The dielectric constant of water is significantly reduced, while the ion product increases exponentially. This unique physicochemical environment greatly enhances the dissociation kinetics of pollutants in fly ash. Simultaneously, the polarity of subcritical water decreases, promoting the dissolution of dioxins. Unlike solid-phase reactions, dioxin degradation under subcritical conditions occurs in the liquid phase, increasing the reaction rate. Furthermore, under the action of a large number of free radicals generated by the auxiliary agents, effective dechlorination, detoxification, and mineralization of dioxins are achieved, resulting in degradation.

[0068] In step S3 of this embodiment, the de-heavy and de-hardening agent is a combination of sodium sulfate and sodium carbonate, with a ratio of sodium sulfate to sodium carbonate of 2 to 5:1, and the dosage of the de-heavy and de-hardening agent is 3% to 6% of the original ash mass.

[0069] In other embodiments, the de-heavy and hardening agent may also be a combination of alum, sodium sulfate and sodium carbonate to further improve the de-heavy and hardening efficiency and reduce the agent cost.

[0070] In this embodiment, the core equipment of the energy recovery component 303 is a cascaded heat recovery system composed of multiple heat exchangers and cooling towers. The energy of the detoxification reactor 302 is recovered in two stages: the first stage is steam recovery and utilization. The energy in the high-temperature zone (160-180°C) of the detoxification reactor 302 is first transferred to the preheating tank 301 at the front end through depressurization to preheat the next batch of materials. Then, the pressure of the reactor is further reduced by a vacuum pump, and the low-grade steam in the range of 100-120°C is drawn to the front end for material preheating and heating of the feed hopper 101 and slurry-water washing unit 200, realizing rapid energy reuse and shortening the residence time of the material in the low-temperature detoxification reaction. The second stage is the recovery and utilization of energy in the material after the reaction. Energy is recovered through a wide-channel plate heat exchanger. The hot side is the high-temperature slurry discharged from the low-temperature detoxification reactor 302, and the cold side is cooling water. Countercurrent heat exchange is carried out. The cooling water is used for slurrying of the next batch of materials to realize heat reuse. This process can cool the hot discharge material to below 60°C. To ensure the system's thermal balance and stable operation under any conditions, and to handle residual low-grade heat that cannot be recovered, the energy recovery unit 303 is equipped with a cooling tower. Process circulating water or equipment cooling water that still requires further cooling after recovery by the main and auxiliary heat exchangers is pumped to the cooling tower for evaporative heat dissipation, ensuring that the temperature of critical equipment remains within a safe range and maintaining the temperature stability of the entire hydrothermal system. Furthermore, the energy recovery unit 303 is equipped with temperature, pressure, and flow sensors interlocked with automatic regulating valves to intelligently and collaboratively control the plate heat exchanger network and the cooling tower fan. The system automatically optimizes heat distribution and dissipation ratio based on real-time heat load, effectively improving the heat recovery and utilization rate while ensuring safe and stable operation.

[0071] During the heat exchange process of the detoxified slurry, the flow rate of the heat exchanger is 1.2 to 1.8 m / s to prevent solid phase deposition while taking into account both heat exchange efficiency and energy saving.

[0072] In this embodiment, except for the internally recycled materials, all water, steam, and slag in the entire system are recovered and used in the next batch of materials for harmless treatment, effectively eliminating the risk of secondary pollution during the treatment process. Furthermore, by recycling process water according to its quality, most of the relatively clean wastewater is directly recycled, effectively reducing water treatment operating costs and achieving a water replenishment volume of less than 0.5 tons per ton of raw fly ash. The treated washing wastewater and evaporation crystallization desalination are converted into industrial salt products. Simultaneously, the detoxified fly ash that meets relevant national standards is co-processed with waste incinerator slag for resource recovery, producing non-fired bricks that meet national standards.

[0073] Example 2 This embodiment provides a system and method for the whole-process treatment and resource utilization of fly ash from municipal solid waste incineration. The specific operation steps are as follows: Step S1: The fly ash produced by the incineration of municipal solid waste is collected from the flue of the incinerator and then enters the feed hopper 101.

[0074] Step S2: Fly ash enters slurry tank 201, the liquid-solid ratio is controlled at 3:1, the stirring paddle 2014 is started, the speed is set to 100 rpm, and the mixture is stirred for 10 minutes to form a uniform slurry; the slurry is pumped into primary washing tank 202.

[0075] Step S3: Start the circulation pump 2025, set the flow rate to 100 m3 / h, establish and maintain a circulation flow rate of 1.5 m / s in the primary washing tank 202, and intensify washing for 10 minutes. Then, the slurry is pumped into the primary dewatering device 203 by a screw pump for solid-liquid separation. Under a pressing pressure of 1.6 MPa, the pressure is maintained for 10 minutes to separate primary wet sludge cake (moisture content 38%) and primary washing liquid. The primary washing liquid enters the gravity and hardening reaction tank 401, and gravity and hardening agents (sodium sulfate:sodium carbonate = 4:1, the amount added is 4% of the original ash mass) are added. After the reaction is complete, it enters the ultrafiltration device 402 for solid-liquid separation. The solid phase enters the preheating tank 301, and the clear liquid enters the nanofiltration device 403 for solid-liquid separation. The chemical sludge is collected for later use, and the clear liquid enters the evaporation and salt separation device 404. Finally, sodium chloride and potassium chloride are crystallized and separated.

[0076] In step S4, the primary wet mud cake enters the primary crushing device 204 and is crushed to a particle size ≤10mm. Then it enters the secondary washing tank 205, and the resulting slurry is transported to the secondary dewatering device 206. At the same time, the condensate generated in the evaporation and salt separation section is added as secondary washing water. Meanwhile, the forced circulation washing and pressure filtration operation in step S3 above is repeated.

[0077] In step S5, the liquid phase of the secondary dewatering device 206 is returned to the slurry tank 201 as slurry washing water, and the solid material generated in the secondary dewatering device 206 is transported to the secondary crushing device 207. In step S6, dechlorination fly ash fragments (soluble chlorine content of 0.75%) are obtained in the secondary crushing unit 207. The dechlorination fly ash fragments, solid material from the ultrafiltration unit 402, chemical sludge from the nanofiltration unit 403, and recycled water are fed into the preheating tank 301, controlling the moisture content to 75%. A detoxification agent (3.5% of the original ash mass) is added to the slurry. The mixed slurry in the preheating tank 301 is preheated to 90°C using the residual heat from the detoxification reactor 302. The preheated slurry is then pumped into the detoxification reactor 302. Under subcritical water conditions, sulfite and loaded transition metal synergistically stimulate a large number of hydroxyl radicals and sulfate radicals, achieving highly efficient reductive dechlorination and oxidative mineralization with significantly reduced dependence on the temperature window.

[0078] Step S7, the parameters of the detoxification reactor 302 are controlled as follows: temperature 170℃, pressure 0.8Mpa, stirring speed 50rpm, and reaction time 45min.

[0079] Step S8: After the reaction is completed, the high-temperature slurry is depressurized through the pressure reducing valve, and the released flash steam is directly introduced into the preheating tank 301 for heating and feeding. Subsequently, the slurry flows through the plate heat exchanger in the energy recovery component 303 to exchange heat with cold water and cool down to 55°C.

[0080] Step S9: The cooled detoxified slurry enters the dewatering equipment 304 for solid-liquid separation to obtain detoxified residue (moisture content 35.6%) and detoxified liquid. The detoxified liquid is recycled back to the preheating tank 301. The qualified detoxified residue enters the brick-making equipment 501 of the tailings resource utilization unit 500. The slag and silicate cement (ratio approximately: detoxified residue: slag: cement = 40:50:10) are metered and mixed. After adding an appropriate amount of water and stirring, the mixture is pressed into shape by a brick press at a pressure of 20MPa. The brick blanks are cured in a standard curing room (temperature 20±2℃, relative humidity >95%) for 28 days, with a compressive strength of 15.3MPa.

[0081] In this embodiment, the forced turbulent scrubbing system can reduce the chlorine content of fly ash to below 1% at room temperature, eliminating the inhibitory effect of chlorine on catalyst activity and creating an optimal chemical environment for low-temperature detoxification. Conventional water washing has limited dechlorination efficiency, and residual chlorine forces the process to rely on higher temperatures to compensate for the reduced reaction activity. Therefore, this embodiment utilizes a "one-agent-two-effect" reagent combined with a "washing" system... The "detoxification" system works in tandem to achieve better simultaneous detoxification results at a lower temperature window.

[0082] Table 1. Chlorine content (wt%) and dioxin toxicity equivalent (ng-TEQ / kg)

[0083] The leaching concentration of the washing residue was determined according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010). The heavy metal concentration should not exceed the maximum allowable emission concentration limit specified in GB8978 (the maximum allowable emission concentration of Class II pollutants shall be implemented in accordance with the Class I standard) as specified in the "Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial)" (HJ1134-2020). The results are shown in Table 2. After system treatment, the heavy metal leaching concentration and dioxin toxicity equivalent both meet the national standard limits.

[0084] Table 2. Heavy metal leaching concentrations and national standard limits

[0085] In this embodiment, by employing forced circulation washing and a corrosion-resistant special washing tank, the system's dechlorination efficiency is effectively improved, the lifespan of key equipment is extended, and the overall operational stability and availability are significantly enhanced. Utilizing a "one-agent-two-effect" low-temperature synergistic reaction system and a high-efficiency heat recovery system, the energy consumption of the core detoxification process is reduced compared to traditional high-temperature technologies. Simultaneously, the reagent dosing system is greatly simplified, reducing material and maintenance costs. Deep and simultaneous removal of heavy metals and dioxins is achieved under a single, mild condition within the detoxification reactor, and the wastewater undergoes thorough resource recovery. The entire process generates virtually no secondary pollutants, ensuring high environmental safety. Furthermore, the final products are converted into building materials and industrial-grade crystalline salt, achieving zero landfill, harmless treatment, and resource recovery of fly ash.

[0086] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A system for the resource utilization of fly ash from municipal solid waste incineration, characterized in that, include: The unit includes a feed buffer unit (100), a pulping-washing unit (200), a low-temperature detoxification unit (300), a water treatment unit (400), and a tailings resource utilization unit (500). The pulping-washing unit (200) includes a pulping tank (201), a primary washing tank (202), a primary dewatering device (203), a primary crushing device (204), a secondary washing tank (205), a secondary dewatering device (206), and a secondary crushing device (207) arranged sequentially. The low-temperature detoxification unit (300) includes a preheating tank (301), a detoxification reactor (302), an energy recovery component (303), and a dehydration device (304) arranged in sequence. The feed buffer unit (100) is connected to the slurry tank (201), the filtrate outlet of the primary dewatering device (203) is connected to the water treatment unit (400), the filtrate outlet of the secondary dewatering device (206) is connected to the primary washing tank (202), and the ash outlet of the secondary crushing device (207) is connected to the preheating tank (301). The steam exhaust port of the detoxification reactor (302) is connected to the preheating tank (301); the filtrate outlet of the dewatering device (304) is connected to the preheating tank (301), and the solid material outlet of the dewatering device (304) is connected to the tailings resource utilization unit (500). The solid material outlet of the water treatment unit (400) is connected to the preheating tank (301), and the condensate outlet of the water treatment unit (400) is connected to the secondary washing tank (205). The primary washing tank (202) is provided with a discharge port at its bottom, and a three-way control valve is provided on the discharge port; a forced return pipe (2024) is provided on the outside of the primary washing tank (202), the discharge end of the forced return pipe (2024) is connected to the upper part of the primary washing tank (202), a circulation pump (2025) is provided on the forced return pipe (2024), the inlet end of the circulation pump (2025) is connected to one of the outlets of the three-way control valve through a pipe, and the other outlet of the three-way control valve is connected to the discharge pipe (2026) to form an external high-speed circulation loop; The sensible heat of the slurry in the detoxification reactor (302) is recycled through the energy recovery component (303) to rapidly cool down the high-temperature detoxification slurry; Furthermore, the bottom outlet of the detoxification reactor (302) is equipped with a pull-out large-aperture mesh box.

2. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that, The water treatment unit (400) includes a gravity and hardness removal reaction tank (401), an ultrafiltration device (402), a nanofiltration device (403), and an evaporation and salt separation device (404) arranged in sequence. The solid material outlet of the ultrafiltration device (402) is connected to the preheating tank (301), the dense material outlet of the nanofiltration device (403) is connected to the preheating tank (301), and the condensate outlet of the evaporation and salt separation device (404) is connected to the secondary washing tank (205).

3. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that, The energy recovery component (303) is a cascaded heat recovery system consisting of multiple heat exchangers and cooling towers; the latent heat of the depressurized steam in the detoxification reactor (302) is recovered for heat tracing in the preheating tank (301).

4. The municipal solid waste incineration fly ash resource utilization system according to any one of claims 1 to 3, characterized in that, The slurry tank (201) is equipped with a stirring paddle (2014), which has multiple serrated blades (2015) in the vertical direction; the inner side wall of the slurry tank (201) is equipped with a U-shaped baffle (2016), and the stirring paddle (2014) and the U-shaped baffle (2016) work together to form a strong shear and turbulent field.

5. The municipal solid waste incineration fly ash resource utilization system according to any one of claims 1 to 3, characterized in that, The primary washing tank (202) and the secondary washing tank (205) have the same structural configuration; the primary washing tank (202) is equipped with an axial flow agitator (2023), the axial flow agitator (2023) is provided with multiple layers of agitator impellers in the vertical direction, and each layer of agitator impellers faces the bottom of the primary washing tank (202); the inner wall of the primary washing tank (202) is provided with multiple layers of deflection baffles (2022) in the vertical direction, and the deflection directions of two adjacent layers of deflection baffles (2022) are opposite.

6. A process for the resource utilization of fly ash from municipal solid waste incineration, characterized in that, The system for resource recovery of municipal solid waste incineration fly ash according to any one of claims 1 to 5, which performs water washing and dechlorination, dioxin removal, and heavy metal solidification on fly ash, includes the following steps: Step S1: The fly ash generated from the incineration of municipal solid waste is collected from the incinerator flue and then enters the feed buffer unit (100). In step S2, the fly ash in the feed buffer unit (100) is conveyed to the pulping tank (201) for pulping treatment, and the resulting slurry is conveyed to the primary washing tank (202). Step S3: After the slurry is washed and dechlorinated in the primary washing tank (202), it is transported to the primary dewatering device (203). The liquid phase material generated by the primary dewatering device (203) is transported to the water treatment unit (400) for chloride recovery and utilization. The solid phase material generated by the primary dewatering device (203) is transported to the primary crushing device (204). Step S4: The slag produced in the primary crushing device (204) is transported to the secondary washing tank (205) for secondary washing and dechlorination, and the resulting slurry is transported to the secondary dewatering device (206). Step S5: The liquid material generated in the secondary dewatering device (206) is recycled to the primary washing tank (202), and the solid material generated in the secondary dewatering device (206) is transported to the secondary crushing device (207). Step S6: The slag produced in the secondary crushing device (207) is transported to the preheating tank (301), where water and detoxification agent are added, and the materials are mixed and preheated. Step S7: The waste heat mixture in the preheating tank (301) is transported to the detoxification reactor (302) for detoxification reaction to achieve heavy metal stabilization and dioxin degradation. Step S8: After the detoxification reaction is completed, the depressurized steam in the detoxification reactor (302) is recycled to the preheating tank (301) to preheat the mixture. The high-temperature detoxified slurry in the detoxification reactor (302) is transported to the energy recovery component (303) for cooling and heat recovery. Step S9: The detoxified slurry after cooling is transported to the dewatering equipment (304). The liquid phase material generated in the dewatering equipment (304) is recycled to the preheating tank (301). The solid phase material generated in the dewatering equipment (304) is transported to the tailings resource utilization unit (500) to realize the tailings disposal.

7. The process for resource recovery of fly ash from municipal solid waste incineration according to claim 6, characterized in that, In step S6, the dosage of the detoxification agent is 3% to 10% of the original ash mass; the components of the detoxification agent include: iron salt, sulfite, sulfate, organic composite agent and supported transition metal catalyst; by weight, the iron salt is 20 to 40 parts, the sulfite is 10 to 25 parts, the sulfate is 15 to 30 parts, the organic composite agent is 5 to 15 parts, and the supported transition metal catalyst is 5 to 15 parts.

8. The process for resource recovery of fly ash from municipal solid waste incineration according to claim 6, characterized in that, In step S6, the mixture is preheated to 80°C to 95°C in a preheating tank (301), and the moisture content of the material in the preheating tank (301) is 70% to 80%.

9. The process for resource recovery of fly ash from municipal solid waste incineration according to claim 6, characterized in that, In step S7, the detoxification reaction is carried out at a temperature of 160℃~180℃, a pressure of 0.6Mpa~1.0Mpa, and a time of 30~60min.

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