An incinerator waste residue heavy metal on-line fluidization mineralization encapsulation and solidification system and method

Abstract

The application discloses a kind of incinerator waste residue heavy metal on-line fluidization mineralization encapsulation solidification system and method.The system is directly connected in series and integrated in solid waste incinerator tail end discharge end, including ash slag pretreatment unit, material metering feeder, multifunctional continuous pre-mineralization mixing screw device, mixed gas reaction fluidized bed reactor and gas-solid separation and circulation unit.The application utilizes high-temperature ash slag heat, completes pre-mineralization in 80-250 DEG C in mixing screw device, then carries out crystallization reform in 700-750 DEG C in fluidized bed reactor by means of fluidized mixed gas containing water vapor, constructs sodalite group mineral matrix in situ on the surface of ash slag particle, and makes heavy metal ions chemically bonded and encapsulated in cage-like crystal lattice by isomorphism replacement mechanism.The system is equipped with pressure pulsation on-line monitoring and closed-loop anti-caking control module, and utilizes incinerator itself flue gas and waste heat steam to build composite fluidization air source, realizes continuous, on-line, low-energy-consumption long-term stabilization treatment of incinerator waste residue heavy metal.

Description

Technical Field

[0001] This invention relates to the field of heavy metal pollution control in solid waste incineration residue, and particularly to an online fluidized mineralization encapsulation and solidification system and method for heavy metals in incinerator waste residue. Background Technology

[0002] Municipal solid waste incineration, hazardous waste incineration, medical waste incineration, and industrial sludge incineration are important technological means to achieve waste reduction, harmlessness, and energy recovery. However, the incineration process inevitably produces a large amount of bottom ash and fly ash, which are enriched with various heavy metals such as Pb, Cd, Cr, Cu, Zn, Ni, and Ba, as well as soluble chloride and sulfate salts. Incineration residues with toxic and hazardous properties must undergo stabilization treatment before being sent to landfills or used for building material resource utilization. Standards such as GB 16889-2024 have put forward stricter leaching toxicity limits for the management of incineration fly ash entering the site.

[0003] Currently, the technical routes for stabilizing heavy metals in incinerator waste residue are mainly divided into two categories: offline treatment and online treatment.

[0004] In terms of offline treatment, cement solidification technology is the most mature, using hydration products to physically encapsulate and surface-adsorb heavy metals. However, the solidified body has a large volumetric increase ratio and is sensitive to acidic leaching environments and chloride and sulfate corrosion, resulting in insufficient long-term stability. Chemical stabilization (such as sulfides, phosphates, and chelating agents) can selectively precipitate heavy metals, but the resulting precipitates still face the risk of re-dissolution under carbonization, wet-dry cycles, and long-term water-rock action. Geopolymer solidification utilizes aluminosilicate raw materials such as fly ash and slag to form a three-dimensional gel network under alkali activation, but often requires high alkali activation conditions. At high pH, ​​metallic aluminum in the bottom ash may evolve hydrogen, leading to increased matrix porosity, and some heavy metals still exist primarily in a physically encapsulated or gel-adsorbed state. Melting vitrification technology can melt ash and slag into a glassy state at temperatures above 1200 ℃, achieving excellent solidification results, but it consumes extremely high energy, requires large equipment investments, and faces significant challenges in controlling the dispersion of volatile heavy metals such as Pb and Cd at high temperatures. More importantly, the above-mentioned offline disposal methods are all intermittent modes of "discharge first, then process". After the ash is discharged from the incinerator, it needs to be cooled, transferred, and stored before entering the stabilization chemical section. This not only increases logistics and land costs, but also wastes a lot of heat carried by the high-temperature ash (usually 400-700℃), which means that energy needs to be repeatedly supplied when heating to the reaction temperature. The overall process thermal efficiency is low.

[0005] Regarding online treatment, a few studies have attempted to incorporate stabilization methods pre- or simultaneously with the incineration ash discharge process. For example, calcium-based or phosphate-based fixatives are directly injected into the flue gas duct at the tail end of the incinerator to utilize the waste heat of the flue gas for preliminary stabilization. However, this type of method mainly relies on surface chemical reactions, making it difficult to achieve deep lattice-level solidification of heavy metals, and the long-term geochemical stability of the stabilized products remains questionable. Another example is the direct co-incineration of clay minerals in a fluidized bed incinerator. However, the main incineration conditions (850-1100℃) far exceed the optimal crystallization temperature range (600-780℃) for aluminosilicate minerals, resulting in the ineffective formation of sodalite group minerals and instead the generation of a large amount of non-target high-temperature phases.

[0006] In the field of radioactive waste treatment, fluidized bed steam reforming (FBSR) technology offers important technological insights. This technology uses a superheated steam atmosphere at 650-850℃ to pyrolyze organic waste and react the inorganic residue with aluminosilicate precursors such as kaolinite to generate alkali metal aluminosilicate minerals with cage-like or channel-like frameworks, such as sodalite, zoisite, and nepheline. These minerals can be used to contain Cs through charge compensation, isomorphous substitution, and lattice inclusion. + 、Sr 2+ Nuclide and TcO4 - Cl - SO4 2- Anions are fixed inside the crystal lattice, exhibiting excellent long-term chemical durability and leaching resistance. However, FBSR technology is designed for radioactive waste, with complex and expensive systems, and operates in an intermittent or semi-intermittent mode, making it difficult to directly adapt to municipal and industrial incinerator slag scenarios that handle large volumes of waste with fluctuating material composition.

[0007] The waste residue system from incinerators differs significantly from that from radioactive waste resin pyrolysis residue: incinerator waste residue contains high levels of CaO, Fe2O3, and various variable-valence heavy metals, with complex mineral composition and particle size distribution. Heavy metals may be present in the glass phase, oxides, chlorides, sulfates, carbonates, or surface adsorbed states. Simply applying cement solidification or geopolymer processes makes it difficult to induce heavy metals into stable mineral lattices; direct melting treatment results in high energy consumption and a high risk of heavy metal volatilization; and adopting FBSR technology requires addressing the engineering challenges of continuous operation, large-scale production, and online coupling with the incinerator.

[0008] In summary, current technologies lack a systematic solution that can utilize the heat from incinerator slag online, operate continuously with low energy consumption, and deeply solidify heavy metals within a stable mineral lattice. There is an urgent need to develop an online mineralization, encapsulation, and solidification system for heavy metals that is integrated in series at the tail end of the incinerator, utilizes the sensible heat of the ash slag and the waste heat from the incinerator's own flue gas, and features fluidized continuous operation as its core characteristic. Summary of the Invention

[0009] To address the bottlenecks in existing heavy metal stabilization technologies for incinerator waste, such as the high energy consumption and low thermal efficiency resulting from the offline treatment mode requiring cooling-transfer-reheating, and the insufficient long-term stability due to the difficulty of inducing heavy metals into stable mineral lattices using existing solidification methods, this invention provides an online fluidized mineralization encapsulation and solidification system and method for heavy metals in incinerator waste. This system is integrated in series at the tail discharge end of the solid waste incinerator, utilizing the heat from high-temperature ash slag online to achieve lattice-level deep solidification of heavy metals and online stabilization transformation of waste slag through continuous fluidized operation.

[0010] To achieve the above objectives, the present invention provides an online fluidized mineralization encapsulation and solidification system for heavy metals in incinerator waste residue. The system is directly integrated in series at the tail discharge end of the solid waste incinerator, comprising: The ash and slag pretreatment unit is used to intercept high-temperature fly ash online and mechanically crush high-temperature bottom ash into a preset particle size range so as to directly utilize the heat of the ash and slag. The material metering and feeding device is used to continuously meter and output aluminosilicate precursors, alkali activators and optional structure guiding agents in proportion; The multifunctional continuous premineralization mixing screw device has its feed end connected to the ash and slag pretreatment unit and the material metering and feeding device. The mixing screw device uses the sensible heat of the ash and slag to maintain a preset premineralization temperature zone so that the material can complete solid-solid mass transfer and surface premineralization wetting during the high-shear propulsion process. The discharge end of the mixing screw device is provided with a tapered extrusion sealing section. The mixed material is continuously compacted in the tapered extrusion sealing section to form a continuous dense sealing to withstand the back pressure of the fluidized bed reactor and suppress the upstream reverse flow of the reaction gas. The mixed gas reaction fluidized bed reactor has its material inlet connected to the discharge end of the mixing screw, and the bottom of the reactor is connected to a mixed gas distribution system. The reactor maintains a high temperature crystallization zone, so that the pre-mineralized material undergoes skeletal rearrangement and in-situ lattice solidification reaction in a fluidized state. The gas-solid separation and circulation unit is connected to the flue gas outlet at the top of the fluidized bed reactor and is used to capture the fine particles released and return them to the bottom of the reactor.

[0011] As a preferred embodiment of the present invention, the multifunctional continuous premineralization mixing screw device is externally wrapped with a waste heat recovery insulation jacket. The jacket is connected to the flue of the solid waste incinerator or the waste heat boiler, which stably controls the temperature inside the mixing screw device within the premineralization temperature range of 80-250℃. The blades inside the mixing screw device adopt a gradually narrowing design with variable pitch or variable blade outer diameter, so that the mixed material is gradually compacted at the discharge end to form a continuous and dense material seal that resists back pressure, thereby preventing the reaction gas in the fluidized bed reactor from flowing backwards into the mixing screw device.

[0012] As a preferred embodiment of the present invention, the mixed gas reaction fluidized bed reactor adopts a segmented differential topology, including a dense phase reaction zone at the bottom and a top anti-sedimentation expansion section; the bottom of the dense phase reaction zone is provided with a gas distribution plate, and the upper side wall is provided with a thermocouple, an overflow product discharge valve and a pressure pulsation sensor; the anti-sedimentation expansion section is used to reduce the apparent flow rate of the gas phase and settle fine particles, and its top outlet is connected to the high-temperature cyclone separator of the gas-solid separation and circulation unit.

[0013] In a preferred embodiment of the present invention, the system further includes a central processing unit; the central processing unit is used to acquire and process the bed pressure drop signal in the dense phase zone of the reactor in real time, and to calculate the standard deviation σ of the pressure drop signal and the average particle circulation time. t ac The system assesses the tendency of bed agglomeration and loss of flow online, and achieves dynamic intervention against agglomeration by issuing closed-loop adjustment commands to the material metering and feeding device to replenish precursors.

[0014] In a preferred embodiment of the present invention, the mixed gas distribution system is connected to a gas thermal integrated distribution unit. The inlet pipe of the gas thermal integrated distribution unit is connected to the high-temperature flue gas pipe of the solid waste incinerator and the superheated steam pipe of the waste heat boiler. The gas thermal integrated distribution unit continuously mixes and produces a composite fluidized air source containing carbon dioxide, residual oxygen, and superheated steam with a volume fraction of not less than 40%. The CO2 and residual O2 naturally present in the incinerator flue gas can serve as auxiliary atmosphere components for the crystallization reaction, while the superheated steam has the dual function of fluidizing medium and crystallization mineralization reaction promoter.

[0015] This invention also provides a method for online fluidized mineralization, encapsulation, and solidification of heavy metals in incinerator waste using the above-mentioned system, comprising the following steps: 1) The ash and slag pretreatment unit continuously crushes the bottom ash from the tail end of the solid waste incinerator to a particle size range of 0.5-2 mm, and introduces it together with the intercepted high-temperature fly ash into a multi-functional continuous pre-mineralization mixing screw device. In the screw device, aluminosilicate precursors, alkali activators and structure guiding agents are continuously added according to the formula. 2) By utilizing the sensible heat of ash slag in conjunction with external waste heat insulation, the material in the mixing screw device is continuously advanced and held for 15-30 minutes at a temperature of 80-250℃. This allows the alkali activator to partially melt and induce the kaolin to undergo a pre-mineralization reaction, transforming it into an active precursor. Simultaneously, the pre-mineralized material is continuously compacted at the screw discharge end to form a continuous and dense material seal. While maintaining the airtight isolation effect of the continuous and dense material seal, the pre-mineralized material is continuously transported to the fluidized bed reactor. 3) Fluidizing gas containing water vapor is introduced into the bottom of the fluidized bed reactor, and the apparent gas velocity of the bed is controlled at 0.6-1.0 m / s, maintaining the bed crystallization and reforming temperature at 700-750℃; the active precursor combines with the inherent chloride ions and / or sulfate ions in the ash and slag to undergo deep skeletal rearrangement, and is oriented to crystallize in situ on the surface of the bottom ash and fly ash particles to construct a matrix of sodalite group minerals and / or nepheline group minerals; during this crystallization process, the heavy metal ions released by the ash and slag upon heating replace the alkali metal ions in the crystal lattice through the isomorphic substitution mechanism, and are encapsulated in the generated cage-like crystal lattice cavity by long-term chemical bonding; 4) After the solid material of heavy metal lattice solidification is completed, it is continuously discharged from the overflow valve on the side of the fluidized bed reactor, and after being cooled by the slag cooler, it is directly transported and disposed of as a solid product.

[0016] As a preferred process of the present invention, the fluidized bed reactor described in step 3) has a heterogeneous two-component synergistic fluidization field constructed inside the bed. The high-temperature bottom ash crushed to 0.5-2 mm in step 1) serves as the first component of the fluidized bed, which is a heavy inert bed material, to maintain stable bed heat capacity and gas-solid heat transfer. The fine fly ash and kaolin composite inclusions serve as the second component, which is a light fluidized material. High-frequency particle collisions and solid-solid mass transfer occur in the voids of the bottom ash bed material, and sodalite aggregates are generated on the surface of the bottom ash bed material particles and at independent crystallization sites.

[0017] In step 3), the volume fraction of superheated steam in the fluidized mixed gas is strictly controlled at 40-60%, the volume fraction of oxygen is controlled at 3-10%, and the remainder is carbon dioxide and nitrogen from the incinerator flue gas. This creates a hydrothermal high-temperature mineralization microenvironment at atmospheric or near-atmospheric pressure, which inhibits the uncontrollable volatilization and diffusion of heavy metal ions at temperatures above 750°C.

[0018] In a preferred process of this invention, in step 1), the additive formulation includes kaolin as the aluminosilicate precursor, sodium hydroxide as the alkali activator, and sodium chloride or sodium sulfate as the structure directing agent. The mass ratio of the aluminosilicate precursor, alkali activator, and structure directing agent satisfies 1:(0.3-0.5):(0.1-0.2). By dynamically adjusting the feed rate of the additives, the Na / (Al+Si) molar ratio in the fluidized bed reactor is maintained at 0.45-0.80, and the Al / Si molar ratio at 0.80-1.40. This ensures the directional formation of the target sodalite group mineral phases and inhibits the excessive formation of sodium-rich competing phases such as nepheline.

[0019] As a preferred process of the present invention, the system is equipped with a central processing unit that is electrically connected to the pressure pulsation sensor and the material metering and feeding device; the central processing unit is used to collect and process the bed pressure drop signal in the dense phase zone of the reactor in real time, and calculate the standard deviation σ of the pressure drop signal and the average particle circulation time t that passes through the average value. ac The system implements the following anti-caking dynamic intervention method during continuous operation: 1) The bed pressure drop signal in the dense phase reaction zone is continuously monitored online using a central processing unit. If the calculated standard deviation σ fluctuates abnormally, and the average particle circulation time... t ac When the set safety threshold is exceeded, it is determined that the local enrichment of fusible chlorides or sulfates in the reaction system leads to the risk of material agglomeration and clumping. 2) The central processing unit outputs adjustment commands to the frequency converter corresponding to the aluminosilicate precursor to increase the mass feeding rate of the aluminosilicate precursor, thereby increasing the instantaneous ratio of the mass flow rate of the aluminosilicate precursor to the mass flow rate of the ash. The incremental aluminosilicate precursor forms a dense protective coating layer on the surface of the precursor and the surface of the bed material particles, and reacts with free alkali metal ions in a solid phase to generate high-melting-point alkali metal aluminosilicate minerals. This reduces the content of low-melting-point liquid phase and weakens the liquid bridge adhesion between particles, preventing the fluidized bed from undergoing a defluidization chain reaction due to the stickiness of the ash surface.

[0020] Compared with the prior art, the core innovation and beneficial effects of this invention are as follows: First, this invention is the first to directly connect an aluminosilicate fluidized bed mineralization encapsulation and solidification system in series at the tail end of a solid waste incinerator. After the high-temperature ash is discharged, online pretreatment, premineralization, fluidized crystallization, cooling, and transportation can be completed sequentially, making the mineralization and solidification process continuously connected with the incineration ash discharge process. Compared with traditional offline treatment methods, this system eliminates the steps of ash cooling, transportation, storage, and reheating before treatment, and can directly utilize the sensible heat carried by the high-temperature ash (400-700 ℃) to provide heat for the premineralization and partial crystallization reactions, thereby reducing external heat input and improving the energy utilization efficiency of the incinerator waste stabilization process.

[0021] Secondly, a multi-functional continuous pre-mineralization mixing screw was installed. This device combines material mixing and continuous conveying functions, utilizing the sensible heat of high-temperature ash slag and the heat provided by the waste heat insulation jacket to maintain the material temperature within the pre-mineralization temperature range of 80-250 ℃. Under this temperature condition, the alkali activator forms a locally micro-melting state and promotes the orderly dehydroxylation of kaolin, transforming it into an active metakaolin precursor, allowing each solid component to complete contact, wetting, and pre-mineralization during the conveying process. Its discharge end adopts a tapered extrusion structure, where the high-density mixture forms a continuous and dense material plug under extrusion, thereby preventing fluidizing gas backflow and withstanding the fluidized bed back pressure. This structure can replace high-temperature rotary valves or double-flap valves, which is beneficial for improving the service life and operational reliability of the feed sealing structure under high-temperature, dusty, and abrasive conditions.

[0022] Third, based on the differences in particle size and density between the incinerator bottom ash and fly ash, a dual-component fluidized bed with varying density was constructed. Crushed bottom ash with a particle size of 0.5–2 mm served as a heavy, inert bed material, maintaining stable fluidization and providing necessary heat capacity and temperature buffering. The composite inclusions formed by fine fly ash and kaolin served as a lightweight, active material, allowing for thorough dispersion and circulation within the bed. This utilizes the particle size distribution of the incinerator ash itself to form a suitable bed composition, eliminating the need for additional external inert bed material. This ensures stable fluidization and heat capacity buffering of the fluidized bed while providing a sufficient reaction interface for heterogeneous nucleation and surface coating crystallization of sodalite group minerals.

[0023] Fourth, the flue gas from the incinerator is mixed with superheated steam generated by the waste heat boiler and used as the fluidizing gas. CO2 and residual O2 in the flue gas are used to regulate the crystallization reaction atmosphere, while the superheated steam acts as both the fluidizing medium and the mineralization reaction promoter, maintaining the bed at a mineralization crystallization temperature of 700-750 °C under atmospheric or near-atmospheric pressure. This composite atmosphere facilitates the rearrangement of the aluminosilicate framework, promotes the migration of heavy metal ions at the particle interface and lattice solidification, and effectively suppresses the uncontrolled volatilization of divalent heavy metals at excessively high temperatures by controlling the crystallization temperature. This gas-thermal integration scheme minimizes dependence on external gas sources and heating energy.

[0024] Fifth, a closed-loop anti-caking control module based on bed pressure pulsation signals was implemented. The system calculates the standard deviation of pressure pulsation by real-time acquisition of the pressure drop signal in the dense phase region of the fluidized bed. σ and average particle cycle time t acThis is used to determine the fluidization state of the bed. When fusible chlorides or sulfates become locally enriched, causing particle agglomeration and signs of impending defluidization, the control module increases the feed ratio of kaolin to form a high-temperature resistant coating on the surface of the material particles. It also reduces the generation of low-melting-point liquid phase by consuming free sodium ions, weakening the liquid bridge effect between particles, thereby inhibiting the further expansion of agglomeration and helping to maintain the long-term continuous operation of the system.

[0025] In summary, the online fluidized mineralization encapsulation and solidification system and process for heavy metals in incinerator waste provided by this invention transforms the offline treatment of heavy metal stabilization in incinerator waste from a method involving cooling, transfer, intermittent operation, and reheating to a continuous online treatment method that occurs during the incineration ash discharge process. Simultaneously, it transforms the heavy metal treatment from primarily relying on surface coating and physical embedding into a chemical fixation of mineral lattices, improving the stability of the solidified morphology. This invention provides a continuous, energy-efficient, and stable treatment method for the harmless treatment and resource utilization of solid waste incineration residue. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall process flow and equipment connection of the online fluidized mineralization encapsulation and solidification system for heavy metals in incinerator waste residue in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the ash and slag pretreatment unit in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the material metering and feeding device in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of the multifunctional continuous premineralization mixing screw device in an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the structure of the mixed gas reaction fluidized bed reactor in an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of the gas-solid separation and circulation unit in an embodiment of the present invention.

[0032] Figure 7 This is a schematic diagram of the gas thermal integrated distribution unit in an embodiment of the present invention. Figure 8 This is a flowchart of the anti-caking dynamic intervention control logic in an embodiment of the present invention.

[0033] The attached figures are labeled as follows: 1-Solid waste incinerator; 2-Ash and slag pretreatment unit; 3-Material metering and feeding device; 4-Multi-functional continuous pre-mineralization mixing screw; 5-Mixed gas reaction fluidized bed reactor; 6-Gas-solid separation and circulation unit; 7-Gas thermal integrated regulation unit; 8-External waste heat boiler or flue; 9-Slag cooler; 10-Central processing unit; 11-High-temperature fly ash interceptor; 12-Bottom ash mechanical crusher; 13-High-temperature resistant filter element assembly; 14-High-temperature reverse-flushing ash removal assembly; 15-Fly ash 16-High-temperature airtight ash discharge assembly; 17-Insulated bottom slag feed chute; 18-High-temperature particle size classification assembly; 19-Ash and slag collection outlet; 20-Kaolin loss-in-weight metering bin; 21-Alkali activator loss-in-weight metering bin; 22-Structure guiding agent loss-in-weight metering bin; 23-Weighing sensor assembly; 24-Sealed feeding valve assembly; 25-Anti-bridging and arch-breaking assembly; 26-Variable frequency metering screw feeder assembly; 27-Flexible sealing connection assembly; 28-Sealed collection hopper; 29-Weighing control... 30-Waste heat recovery insulation jacket; 31-Gradual shrinking extrusion sealing section; 32-Mixed gas distribution system; 33-Dense phase reaction zone; 34-Anti-sedimentation expansion section; 35-Thermocouple assembly; 36-Overflow product discharge valve; 37-Pressure pulsation detection component; 38-Pre-mineralized product inlet; 39-Gradual expansion transition section; 40-High temperature cyclone separator; 41-Dust-laden gas tangential inlet; 42-Cylindrical separation section; 43-Conical collection section; 44-Center discharge... 45 - Gas pipe; 46 - Separated gas outlet; 47 - High-temperature return leg; 48 - High-temperature non-mechanical return valve; 49 - Return flow aid gas inlet; 50 - Particle return pipe; 51 - Automatic regulating valve assembly; 52 - High-temperature flue gas inlet branch; 53 - Superheated steam inlet branch; 54 - Branch flow measurement component; 55 - Branch pressure and temperature monitoring component; 56 - Static mixing section; 57 - Mixed gas temperature sensor; 58 - Online gas component analysis component; 59 - Composite fluidizing gas outlet pipe. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0035] The core of this invention lies in directly integrating an aluminosilicate fluidized mineralization encapsulation and solidification system in series at the tail end of a solid waste incinerator. The system utilizes the heat from high-temperature ash (400-700℃) to drive a pre-mineralization reaction online, combined with a water-containing steam fluidized gas mixture for crystallization and reforming at 700-750℃. This constructs a sodalite group mineral matrix in situ on the surface of the ash particles, allowing divalent heavy metal ions to be chemically bonded and encapsulated within a cage-like lattice via isomorphic substitution. Furthermore, an online pressure pulsation monitoring and closed-loop anti-caking control module is configured to ultimately achieve continuous, online, low-energy-consumption, and long-term stable treatment of incinerator waste.

[0036] Reference Figure 1 This document illustrates the overall process flow and equipment connection diagram of the online fluidized mineralization encapsulation and solidification system for heavy metals in incinerator slag in this embodiment of the invention. The system is directly integrated in series at the tail discharge end of the solid waste incinerator 1, and sequentially includes, according to the material flow direction: ash pretreatment unit 2, material metering and feeding device 3, multi-functional continuous premineralization mixing screw device 4, mixed gas reaction fluidized bed reactor 5, gas-solid separation and circulation unit 6 (in this embodiment, a high-temperature cyclone separator is used), and gas thermal integrated regulation unit 7.

[0037] The ash pretreatment unit 2 is used to intercept high-temperature fly ash online and mechanically crush the high-temperature bottom ash to a preset particle size range to directly utilize the heat of the ash. The material metering and feeding device 3 is used to continuously meter and output aluminosilicate precursors, alkali activators, and optional structure-directing agents in proportion. The multifunctional continuous premineralization mixing screw device 4 uses the sensible heat of the ash to maintain a preset premineralization temperature zone, so that the material completes solid-solid mass transfer and surface premineralization wetting during high-shear propulsion. The discharge end of the mixing screw forms a dense material plug with air-locking function through a tapered extrusion structure. The mixed gas reaction fluidized bed reactor 5 maintains a high-temperature crystallization temperature zone, so that the premineralized material undergoes skeletal rearrangement and in-situ lattice solidification reaction in a fluidized state. The gas-solid separation and circulation unit 6 is connected to the flue gas outlet at the top of the fluidized bed reactor to capture the dispersed fine particles and return them to the bottom of the reactor. The gas thermal integration and blending unit 7 is used to mix and produce a composite fluidized gas mixture, which is then introduced into the bottom of the fluidized bed reactor via the air distribution system 32. The online fluidized bed mineralization and solidification system for heavy metals in incinerator waste is also equipped with a slag cooler 9 and a central processing unit 10. The high-temperature solid products overflowing from the mixed gas reaction fluidized bed reactor 5 are cooled by the slag cooler 9 and then transported off-site. The central processing unit 10 is electrically connected to the pressure pulsation detection component 37 and the material metering and feeding device 3 to form a closed-loop anti-caking control circuit. The gas inlet pipes of the gas thermal integrated distribution unit 7 are respectively drawn from the high-temperature flue gas pipes of the external solid waste incinerator 1 and the superheated steam pipes of the external waste heat boiler or flue 8.

[0038] Reference Figure 2This is a schematic diagram of the structure of the ash pretreatment unit 2 in this embodiment of the invention, including a high-temperature fly ash interceptor 11 and a bottom ash mechanical crusher 12. The high-temperature fly ash interceptor 11 is equipped with a high-temperature resistant filter element assembly 13, a high-temperature backflushing cleaning assembly 14 at its top, and a fly ash collection hopper 15 at its bottom. When high-temperature flue gas passes through the high-temperature resistant filter element assembly 13, fly ash is intercepted on the surface of the filter element. The high-temperature backflushing cleaning assembly 14 backflushes the filter element at a set cycle, causing the adhering fly ash to fall into the fly ash collection hopper 15. The fly ash is discharged through a high-temperature airtight ash discharge assembly 16. The high-temperature bottom ash discharged from the solid waste incinerator 1 enters the bottom ash mechanical crusher 12 through an insulated bottom ash feed chute 17. The crushed bottom ash enters a high-temperature particle size classification assembly 18; coarse particles on the sieve are returned to the bottom ash mechanical crusher 12 for further crushing, while bottom ash of the qualified particle size enters the ash collection outlet 19. The fly ash discharged from the high-temperature airtight ash discharge component 16 and the qualified particle size bottom ash are combined at the ash and slag collection outlet 19 and then enter the multi-functional continuous pre-mineralization mixing screw device 4.

[0039] Reference Figure 3 This is a schematic diagram of the material metering and feeding device 3 in this embodiment of the invention, including a kaolin loss metering bin 20, an alkali activator loss metering bin 21, and a structure guiding agent loss metering bin 22. Each metering bin is supported by a weighing sensor group 23, and a sealed feeding valve group 24 is provided at the top. An anti-bridging and arch-breaking component 25 is provided in the conical section of the bin body. The lower part of each metering bin is connected to a variable frequency metering screw feeder group 26. The feeding port and discharge port of the metering bin are provided with flexible sealing connection components 27 to reduce the influence of external pipeline load and equipment vibration on the weighing signal. The three additives are discharged through the variable frequency metering screw feeder group 26 and enter the sealed collection hopper 28, and are then fed into the multi-functional continuous pre-mineralization mixing screw device 4 by the sealed collection hopper 28. The weighing control and variable frequency drive unit 29 receives the signal from the weighing sensor group 23 and adjusts the speed of the corresponding metering screw according to the mass change of each metering bin per unit time. The weighing control and variable frequency drive unit 29 is communicatively connected to the central processing unit 10. When abnormal fluctuations occur in bed pressure, the central processing unit 10 adjusts the output of the kaolin feeding channel through the weighing control and frequency conversion drive unit 29.

[0040] Reference Figure 4This is a schematic diagram of the multifunctional continuous premineralization mixing screw device 4 in this embodiment of the invention. The screw device is externally encased in a waste heat recovery insulation jacket 30, through which a heat medium from the solid waste incinerator flue or waste heat boiler is introduced to stably control the internal temperature of the screw device within the premineralization temperature range of 80-250℃. The screw blades inside the screw device adopt a tapered design with a gradually decreasing pitch and gradually increasing outer diameter from the feed end to the discharge end. A tapered extrusion sealing section 31 is formed at the discharge end, where the mixed material is continuously compacted to form a continuous dense sealing layer, thus withstanding the back pressure of the fluidized bed reactor and suppressing the upstream countercurrent flow of reactant gases.

[0041] Reference Figure 5 This is a schematic diagram of the structure of the mixed gas reaction fluidized bed reactor 5 in this embodiment of the invention. The lower part is a dense phase reaction zone 33, and a mixed gas distribution system 32 is provided at the bottom of the dense phase reaction zone 33. The mixed gas distribution system 32 uses a gas distribution plate to ensure that the composite fluidized gas enters the bed uniformly from the bottom of the reactor. A thermocouple assembly 35 and a pressure pulsation detection component 37 are provided along the height direction on the sidewall of the dense phase reaction zone 33. The thermocouple assembly 35 is used to measure the temperature at different bed heights. The pressure pulsation detection component 37 may include upper and lower pressure taps arranged along the bed height, as well as differential pressure or pressure signal acquisition elements, for obtaining bed pressure drop and pressure fluctuation signals. An overflow product discharge valve 36 is also provided on the sidewall of the dense phase reaction zone 33 for continuously discharging solid products that have reached the set bed height. The upper part of the dense phase reaction zone 33 is connected to the anti-sedimentation expansion section 34 via a gradually expanding transition section 39. The inner diameter of the anti-sedimentation expansion section 34 is 1.5 times the inner diameter of the dense phase reaction zone 33. The gradual expansion transition section 39 can reduce local disturbances caused by sudden expansion. After the gas enters the anti-sedimentation expansion section 34, the apparent velocity decreases, and some fine particles return to the dense phase reaction zone 33 under gravity. The pre-mineralized product inlet 38 is located on the side of the gradual expansion transition section 39 and is connected to it. Figure 4 The outlet of the gradually shrinking extrusion sealing section 31 is connected. The dust-laden gas at the top of the anti-dust expansion section 34 enters the gas-solid separation and circulation unit 6. The gas-solid separation and circulation unit 6 adopts a high-temperature cyclone separator. The separated gas is discharged from the top of the cyclone separator, and the captured fine particles are returned to the lower part of the dense phase reaction zone 33 through the material leg and return pipe.

[0042] Reference Figure 6This is a schematic diagram of the gas-solid separation and circulation unit 6 in this embodiment of the invention. It is connected to the upper outlet of the mixed gas reaction fluidized bed reactor 5 and communicates with the lower part of the dense phase reaction zone 33. It is used to separate fine particles in the exhaust gas flow from the anti-sedimentation expansion section 34 and return them to the reactor 5. The gas-solid separation and circulation unit 6 includes a high-temperature cyclone separator 40, a dust-laden gas tangential inlet 41, a cylindrical separation section 42, a conical collection section 43, a central exhaust pipe 44, a separated gas outlet 45, a high-temperature return leg 46, a high-temperature non-mechanical return valve 47, a return flow aid gas inlet 48, and a particle return pipe 49. The dust-laden gas flow enters the high-temperature cyclone separator 40 through the dust-laden gas tangential inlet 41. The particles fall along the wall of the separator into the conical collection section 43 under the action of the rotating air flow. The separated gas is discharged through the central exhaust pipe 44 and the separated gas outlet 45. The conical collecting section 43 is connected to the dense phase reaction zone 33 via a high-temperature return leg 46, a high-temperature non-mechanical return valve 47, and a particle return pipe 49. The high-temperature non-mechanical return valve 47 preferably employs a material seal type or an L-shaped return structure. The return flow-aiding gas inlet 48 is used to introduce flow-aiding gas to maintain continuous particle return and suppress gas backflow. The particle return pipe 49 is connected above the mixed gas distribution system 32 and below the overflow product discharge valve 36, allowing the collected fine particles to return to the dense phase reaction zone 33 to continue participating in the reaction.

[0043] Reference Figure 7 This is a schematic diagram of the gas thermal integrated distribution unit 7 in this embodiment of the invention. It is used to mix high-temperature flue gas from the incineration system and superheated steam from the waste heat boiler, and to transport the resulting composite fluidized gas to the mixed gas reaction fluidized bed reactor 5. The gas thermal integrated distribution unit 7 includes an automatic regulating valve group 50, a high-temperature flue gas inlet branch 51, a superheated steam inlet branch 52, a branch flow measurement component 53, a branch pressure and temperature monitoring component 54, a static mixing section 55, a mixed gas temperature sensor 56, an online gas component analysis component 57, and a composite fluidized gas outlet pipe 58. The high-temperature flue gas inlet branch 51 and the superheated steam inlet branch 52 are respectively connected to the flue gas pipeline at the tail end of the incinerator and the superheated steam pipeline of the waste heat boiler. The branch flow measurement component 53, the branch pressure and temperature monitoring component 54, and the automatic regulating valve group 50 are installed on the two branches to monitor and regulate the flow rate, pressure, temperature, and mixing ratio of the two gases. The automatic regulating valve group 50 preferably includes a regulating valve, a check valve, and a shut-off valve. The two gas streams converge into the static mixing section 55 after passing through the automatic regulating valve group 50. The mixed gas then undergoes temperature and composition monitoring via the mixed gas temperature sensor 56 and the online gas component analysis component 57, before being sent to the mixed gas distribution system 32 through the composite fluidized gas outlet pipe 58. The gas thermal integrated distribution unit 7 can operate independently without requiring a control connection to the central processing unit 10. (Refer to...) Figure 8This is a flowchart illustrating the dynamic intervention control logic for anti-caking in this embodiment of the invention. The central processing unit 10 continuously collects the bed pressure drop signal from the pressure pulsation detection component 37 online and calculates the standard deviation σ and the average particle cycle time in real time. t ac .when σ Abnormal fluctuations and t ac When the set safety threshold is exceeded, it is determined that there is a risk of agglomeration due to local enrichment of fusible salt. The central processing unit 10 sends an adjustment command to the weighing control and frequency conversion drive unit 29 to increase the output of the frequency conversion metering screw feeder group 26 in the kaolin channel. After the pressure fluctuation returns to the normal range, the feed rate gradually returns to the original set value.

[0044] The technical solution and beneficial effects of the present invention will be described in detail below with reference to specific embodiments and comparative examples. The solid waste incinerator used in the following embodiments is a 750 t / d mechanical grate incinerator of a municipal solid waste incineration plant, with a slag discharge temperature of about 550-650℃ and a tail flue fly ash temperature of about 400-500℃.

[0045] Example 1 This embodiment demonstrates the basic operating scheme of the system of the present invention, in order to prove the technical effect of the online fluidized mineralization encapsulation and solidification process.

[0046] (1) Ash and slag pretreatment: The high-temperature bottom ash (approximately 600°C) discharged from the upstream solid waste incinerator is directly fed into the bottom ash mechanical crusher 12 of the ash and slag pretreatment unit 2, and crushed online to a particle size range of 0.5-2 mm. At the same time, the high-temperature fly ash (approximately 450°C) in the tail flue of the incinerator is intercepted online through the high-temperature resistant filter element assembly 13 (high-temperature resistant metal filter bag or ceramic fiber tubular filter). Neither the bottom ash nor the fly ash is cooled, and its heat is directly utilized to enter the multi-functional continuous pre-mineralization mixing screw device 4.

[0047] (2) Additive metering and premineralization mixing: The material is continuously metered and output according to the mass ratio of kaolin:sodium hydroxide:sodium chloride 1:0.5:0.15 through the material metering and feeding device 3. Among them, the addition ratio of kaolin (#1 chiral powder, China Kaolin Co., Ltd.) relative to the total mass of ash (bottom ash + fly ash, mass ratio of about 4:1) is 20wt%. The above-mentioned high-temperature ash and additives enter the multi-functional continuous premineralization mixing spiral device 4. The sensible heat of the ash (about 550-600℃) and the auxiliary temperature regulation of the waste heat recovery insulation jacket 30 are used to stabilize the material temperature in the spiral device at the premineralization temperature zone of 180-200℃. The material is continuously pushed and stays in the spiral device for about 20 minutes. During this period, NaOH undergoes local micro-melting and induces kaolin to dehydroxylate and transform into metakaolin active precursor, completing solid-solid premineralization. The discharge end forms a continuous and dense airlock material plug through the gradually shrinking extrusion sealing section 31, and the pre-mineralized product finally enters the fluidized bed reactor 5.

[0048] (3) Fluidized Crystallization Reaction: The inlet pipe of the gas thermal integrated distribution unit 7 is connected to the high-temperature flue gas pipe of the solid waste incinerator and the superheated steam pipe of the waste heat boiler. The high-temperature flue gas and superheated steam are distributed into a composite fluidized mixed gas through the valve group. The volume fraction of the mixed gas is: water vapor 48%, CO2 32%, O2 7%, N2 13% (of which CO2 and part of N2 come from the flue gas of the incinerator, O2 is the residual oxygen in the flue gas, and water vapor comes from the superheated steam of the waste heat boiler). The total gas flow rate is controlled according to the apparent gas velocity of the bed layer of 0.8 m / s. The mixed gas enters the dense phase reaction zone 33 through the air distribution system 32. The bed temperature is stably controlled at 725 ℃, and the material stays in the fluidized state for about 60 min. During this period, the metakaolin active precursor combines with the Cl inherent in the fly ash. - On the surface of bottom slag and fly ash particles, skeletal rearrangement occurs, leading to directional crystallization and the formation of sodalite (Na8(AlSiO4)6Cl2). Simultaneously, divalent heavy metal ions (Pb) are released from the ash upon heating. 2+ Cd 2+ Cu 2+ Zn 2+ (etc.) replaces monovalent Na in the sodalite lattice via isomorphic substitution mechanism. + The particles maintain lattice electroneutrality by generating cation vacancies and are ultimately chemically bonded and encapsulated within the sodalite β-cage cavity. During the reaction, the dust-laden gas stream discharged from the upper part of the anti-dust expansion section 34 enters the gas-solid separation and circulation unit 6, where it undergoes gas-solid separation via a high-temperature cyclone separator 40. The collected fine particles are returned to the lower part of the dense phase reaction zone 33 to continue participating in the reaction. This recycling process increases the residence time and reaction extent of fine particles within the reactor.

[0049] (4) Product cooling and collection: After the solid material has been solidified, it is continuously discharged from the overflow product discharge valve 36 into the slag cooler 9. After being cooled to below 60°C, it is transported out as a raw material for stabilized green building materials. The fine particles separated from the top of the fluidized bed are collected by the high-temperature cyclone separator 40 and then returned to the lower part of the dense phase reaction zone 33 through the material leg. The separated gas is discharged from the top of the cyclone separator.

[0050] Example 1 Operation Results: The system operated continuously for 72 hours, with stable pressure drop in the fluidized bed and no agglomeration or loss of fluidization. XRD analysis showed that the mass fraction of sodalite phase in the discharged product was approximately 65-72 wt%, and the mass fraction of nepheline phase was approximately 12-18 wt%. Compared with the original fly ash, TCLP leaching tests showed that the leaching concentration of Pb in the encapsulated product decreased by 94.2%, Cd by 96.5%, Cr by 91.8%, Cu by 93.1%, and Zn by 95.3%. The leaching concentrations of all heavy metals met the landfill limits for municipal solid waste incineration fly ash in GB 16889-2024. The system's external energy consumption (mainly additives and a small amount of supplementary electric heating) was approximately 58% lower than that of the traditional offline treatment mode (cooling and then reheating to 725℃).

[0051] Example 2 This embodiment, based on Embodiment 1, dynamically adjusts the additive mass flow rate ratio according to the XRF real-time composition analysis results of the feed ash, precisely controlling the Na / (Al+Si) molar ratio in the fluidized bed reactor reaction system to approximately 0.60 and the Al / Si molar ratio to approximately 1.10. The required Al(OH)3 is pre-mixed with kaolin and added through the kaolin loss metering bin 20, without a separate feeding channel. The remaining equipment and operating conditions are the same as in Embodiment 1.

[0052] Compared with Example 1, the mass fraction of sodalite phase in this example is increased to about 73-78 wt%, the mass fraction of nepheline phase is reduced to about 8-12 wt%, and the leaching concentration of Pb is reduced by 96.1%, Cd by 97.1%, Cr by 93.5%, Cu by 93.9%, and Zn by 96.2% compared with the original fly ash. Compared with Example 1, the content of target mineral phases is increased, and the leaching concentration of heavy metals is further reduced.

[0053] Example 3 To verify the broad applicability of the system of the present invention to different types of incinerator ash, bottom ash and fly ash from hazardous waste incineration, bottom ash and fly ash from medical waste incineration, and bottom ash and fly ash from industrial sludge incineration were used as raw materials and continuously operated under the optimized conditions of Example 2.

[0054] Hazardous waste incineration ash: The bottom ash and fly ash contained 3850 mg / kg Pb, 210 mg / kg Cd, and 1560 mg / kg Cr. After operation, the concentrations of Pb, Cd, and Cr in the TCLP leachate of the encapsulated product decreased by 96.8%, 97.3%, and 94.5%, respectively.

[0055] The ash residue from medical waste incineration contains 5230 mg / kg Zn and 1240 mg / kg Cu ​​in the bottom ash and fly ash. After operation, the concentrations of Zn and Cu in the TCLP leachate of the encapsulated product decreased by 94.7% and 93.9%, respectively.

[0056] Industrial sludge incineration ash: The Ni content in the bottom ash and fly ash is 890 mg / kg, and the Ba content is 1350 mg / kg. After operation, the Ni and Ba concentrations in the TCLP leachate of the encapsulated product decreased by 92.8% and 95.1%, respectively.

[0057] The heavy metal leaching concentrations of the encapsulated products obtained from each group of ash residues all met the corresponding standard limits, verifying that the system of the present invention has good raw material adaptability and technical universality.

[0058] Example 4 This embodiment artificially increases the chloride content of the feed ash (adding an additional 3wt% NaCl) to create an extreme working condition of local enrichment of fusible salts, and tests the response effectiveness of the anti-caking dynamic intervention control module.

[0059] Under stable operating conditions in Example 2, the proportion of NaCl in the feed was artificially increased at a certain time (t0). Approximately 15 minutes after t0, the central processing unit 10 detected that the standard deviation σ of the pressure pulsation signal in the dense phase reaction zone began to rise continuously, and the average particle cycle time t ac Gradually deviating from the normal fluctuation range. When σ exceeds the preset safety threshold (2.5 times the normal fluctuation range) and t ac In the event of a synchronization anomaly, the central processing unit 10 sends a command to the weighing control and frequency conversion drive unit 29 to increase the output of the frequency conversion metering screw feeder group 26 in the kaolin channel by 40%. After approximately 8 minutes of adjustment, the pressure pulsation signal gradually returns to the normal range, and σ and t... ac The fluidized bed returned to a safe range. No defluidization or agglomeration / dead-bed accidents occurred throughout the process, verifying the reliability and response speed of the anti-agglomeration control module.

[0060] Because the added chloride salt has a relatively strong structure-directing ability, it can further synthesize minerals by interacting with the system-controlled kaolinite. In this embodiment, the mass fraction of the sodalite phase is increased to about 70-75 wt%, the nepheline phase is reduced to about 9-14 wt%, and the Pb leaching concentration is reduced by 94.5%, Cd by 96.4%, Cr by 92.4%, Cu by 93.3%, and Zn by 96.1% compared to the original fly ash. Compared with Example 1, the content of the target mineral phases is increased, and the heavy metal leaching concentration is further reduced.

[0061] Comparative Example 1 This comparative example demonstrates the crucial role of the water vapor fluidized gas mixture in the system of the present invention. Under the exact same system configuration and operating parameters as in Example 1, only the fluidized gas mixed by the gas thermal integration and blending unit 7 was replaced with dry air (free of water vapor, directly supplied by an air cylinder, with the total flow rate maintained at the same apparent gas velocity), while all other conditions remained unchanged.

[0062] Under anhydrous conditions, the rates of kaolin precursor deconstruction and framework rearrangement in the fluidized bed reactor were significantly reduced. XRD analysis showed that the mass fraction of sodalite phase in the discharged product was only about 21-28 wt%, with a large amount of unreacted kaolin and mesophase residues. TCLP leaching tests showed that the Pb leaching concentration decreased by only about 42% and the Cd concentration by about 38%, far less than the effect of Example 1. This comparative example fully demonstrates that a water vapor-containing hydrothermal microenvironment plays an irreplaceable role in achieving sufficient deconstruction and crystallization of aluminosilicates and lattice solidification of heavy metals under mesotemperature conditions (725°C).

[0063] Comparative Example 2 This comparative example demonstrates the key role of the multifunctional continuous pre-mineralization mixing screw device in the system of this invention. The mixing screw device 4 in the system configuration of Example 1 is replaced with a conventional star-shaped feed valve. The high-temperature ash and additives are directly fed into the fluidized bed reactor 5 through the feed valve after simple mechanical mixing. All other conditions are the same as in Example 1.

[0064] Due to the lack of a pre-mineralization isothermal stage of 80-250℃, kaolin failed to complete orderly dehydroxylation and pre-mineralization into reactive metakaolin before entering the fluidized bed reactor. Direct exposure to 725℃ led to rapid, disordered dehydration, forming an inactive amorphous phase. XRD analysis showed that the mass fraction of sodalite in the discharged product was only about 35-42 wt%, while the nepheline phase increased to about 30-38 wt%. TCLP leaching tests showed that the Pb leaching concentration decreased by only about 68%. Furthermore, due to the lack of a dense material plug formed by a tapered extrusion sealing section, water vapor mixtures frequently backflowed into the feed end of the fluidized bed reactor, causing condensation and blockage of wet material in the feed inlet area, severely impacting the system's continuous operational stability. This comparative example clearly demonstrates that the pre-mineralization temperature zone, high-shear solid-solid mass transfer environment, and gas-locking function provided by the mixing screw are necessary prerequisites for achieving subsequent efficient crystallization encapsulation and continuous stable system operation.

[0065] Comparative Example 3 Take municipal solid waste incineration fly ash and bottom ash from the same source as in Example 1, and process them according to the traditional offline disposal mode: the ash and ash are first cooled to room temperature by water cooling and then transferred to the processing workshop. The fly ash is mixed with P·O 42.5 ordinary Portland cement at a mass ratio of 1:3, an appropriate amount of water is added and stirred evenly, and then poured into molds for molding and standard curing for 28 days.

[0066] Compared to the online fluidized bed encapsulation product of Example 1, the cement-cured body exhibited approximately 15 times higher Pb leaching concentration, approximately 22 times higher Cd concentration, and approximately 18 times higher Zn concentration under TCLP acidic leaching conditions (acetic acid buffer, pH 2.88). Furthermore, the volumetric efficiency of the cement-cured body was approximately 1.6-1.8, significantly higher than the volumetric efficiency of the process of this invention (approximately 1.1-1.2). This comparative example demonstrates that lattice chemical bonding encapsulation offers significantly superior long-term chemical durability compared to physical cement embedding, and that the online process of this invention effectively reduces the solidification volumetric efficiency.

[0067] Comparative Example 4 This comparative example demonstrates the key roles of the aluminosilicate precursor and the alkali activator in the system of this invention. Under the system configuration and operating parameters of Example 1, only the supply of all additives to the material metering and feeding device 3 was stopped; that is, the ash (bottom ash + fly ash) was subjected to fluidized bed heat treatment alone under the same temperature, atmosphere, and residence time conditions, without the addition of kaolin, alkali activator, or structure directing agent. The remaining conditions were the same as in Example 1.

[0068] XRD analysis showed that only the original ash phases (quartz, calcite, calcium aluminum feldspar, etc.) were detected in the discharged product, with no sodalite group minerals formed. TCLP leaching tests showed that the leaching concentrations of each heavy metal were not significantly reduced compared to the original fly ash. This comparative example fully demonstrates that heat treatment alone cannot achieve the stable encapsulation of heavy metals; the introduction of aluminosilicate precursors and alkali activators is the material basis for constructing the cage-like mineral encapsulation matrix.

[0069] To more clearly demonstrate the beneficial effects of the various technical features of the present invention, the key conditions and main results of the above embodiments and comparative examples are summarized in Table 1 below.

[0070] Table 1. Comparison of key conditions and main results between the examples and comparative examples. As can be seen from the data in Table 1: Example 1 used a complete system configuration, and the resulting solidified product had a sodium silicate phase content of 65%-72%, a heavy metal leaching concentration reduction rate of over 90%, and a continuous stable operating time of over 72 hours. Comparative Example 1 simply replaced the water vapor-containing composite fluidizing gas with dry air, keeping all other conditions unchanged. The resulting product had a sodium silicate phase content reduced to 21%-28%, and a heavy metal leaching concentration reduction rate of less than 50%. These results indicate that under the experimental conditions, the hydrothermal reaction environment formed by water vapor is conducive to the rearrangement of the aluminosilicate framework and the lattice solidification of heavy metal ions, and is an important factor affecting the degree of mineralization solidification reaction.

[0071] The results of Example 1 and Comparative Example 2 show that the pre-mineralization mixing screw has a significant impact on the subsequent fluidized bed mineralization process and the continuous operation of the system. Without the pre-mineralization mixing screw, the material failed to complete preheating, mixing, and preliminary mineralization before entering the fluidized bed reactor, resulting in a significant decrease in the sodium carbonate phase content of the obtained product. Simultaneously, due to the lack of a tapered compression airlock structure, the fluidizing gas easily backflows along the feed channel, thus affecting feed stability and the continuous operation of the unit. Therefore, the pre-mineralization temperature zone and its airlock structure are crucial conditions for maintaining the stable operation of this process.

[0072] Compared with Example 1, Example 2 improved the sodalite phase content and heavy metal leaching concentration reduction rate by adjusting the Na / (Al+Si) molar ratio and Al / Si molar ratio of the raw material system to a suitable range for sodalite group mineral formation. This result indicates that the ratio of sodium, aluminum, and silicon in the raw materials directly affects the formation of aluminosilicate crystal phases and the solidification effect of heavy metals.

[0073] The results of Examples 4 and 1 show that, under conditions of high chloride content and increased bed agglomeration tendency, the central processing unit and its closed-loop anti-caking control module can identify abnormal changes based on bed pressure pulsation signals and adjust the kaolin feed rate in a timely manner, thereby suppressing bed agglomeration and de-flow. This control method helps improve the system's adaptability to fluctuations in ash composition and maintains continuous operation of the unit.

[0074] Compared with the simple heat treatment method used in Comparative Example 4, the traditional offline cement curing method used in Example 3 shows that the present invention exhibits better overall performance in terms of heavy metal leaching control, chemical stability of cured products, processing capacity expansion ratio, energy consumption, and continuous operation capability. This is because the present invention does not rely on a single heat treatment or physical encapsulation effect, but rather uses processes such as pre-mineralization, fluidized mineralization, and particle circulation to allow heavy metals to gradually enter the aluminosilicate mineral structure and thus be stably cured.

[0075] Based on the above experimental results, this invention continuously connects processes such as ash pretreatment, additive metering, pre-mineralization mixing, fluidized crystallization, gas-solid separation circulation, and product cooling. Through water-steam composite fluidized gas, synergistic fluidization with varying density particles, and bed state monitoring and adjustment, continuous mineralization of incinerator waste slag can be achieved under conditions of lower external energy consumption. The cooperation between each unit collectively improves mineral formation, heavy metal solidification, and system operational stability.

[0076] The above embodiments are used to illustrate the technical solution of the present invention, and are not intended to limit its scope of protection. Those skilled in the art can make corresponding adjustments to the pre-mineralization temperature, crystallization temperature, additive composition and addition ratio, fluidized bed reactor size, and air distribution structure according to the type of incinerator, ash composition, and processing scale. Equivalent substitutions or conventional improvements made without departing from the technical concept of the present invention should fall within the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

Claims

1. An online fluidized bed mineralization encapsulation and solidification system for heavy metals in incinerator waste residue, characterized in that, The system is directly integrated in series at the tail discharge end of the solid waste incinerator, including: The ash and slag pretreatment unit is used to intercept high-temperature fly ash online and mechanically crush high-temperature bottom ash into a preset particle size range so as to directly utilize the heat of the ash and slag. The material metering and feeding device is used to continuously meter and output aluminosilicate precursors, alkali activators and optional structure guiding agents in proportion; The multifunctional continuous premineralization mixing screw device has its feed end connected to the ash and slag pretreatment unit and the material metering and feeding device. The mixing screw device uses the sensible heat of the ash and slag to maintain a preset premineralization temperature zone so that the material can complete solid-solid mass transfer and surface premineralization wetting during the high-shear propulsion process. The discharge end of the mixing screw device is provided with a tapered extrusion sealing section. The mixed material is continuously compacted in the tapered extrusion sealing section to form a continuous dense sealing to withstand the back pressure of the fluidized bed reactor and suppress the upstream reverse flow of the reaction gas. The mixed gas reaction fluidized bed reactor has its material inlet connected to the discharge end of the mixing screw, and the bottom of the reactor is connected to a mixed gas distribution system. The reactor maintains a high temperature crystallization zone, so that the pre-mineralized material undergoes skeletal rearrangement and in-situ lattice solidification reaction in a fluidized state. The gas-solid separation and circulation unit is connected to the flue gas outlet at the top of the fluidized bed reactor and is used to capture the fine particles released and return them to the bottom of the reactor.

2. The system according to claim 1, characterized in that: The multifunctional continuous premineralization mixing screw device is externally wrapped with a waste heat recovery insulation jacket. The jacket is connected to the flue of the solid waste incinerator or the waste heat boiler, which stably controls the internal temperature of the mixing screw device within the premineralization temperature range of 80-250℃. The blades inside the mixing screw device adopt a gradually narrowing design with variable pitch or variable blade outer diameter, so that the mixed material is gradually compacted at the discharge end to form a continuous and dense material seal that resists back pressure, thereby preventing the reaction gas in the fluidized bed reactor from flowing backwards into the mixing screw device.

3. The system according to claim 1, characterized in that: The mixed gas reaction fluidized bed reactor adopts a segmented differential topology, including a dense phase reaction zone at the bottom and a top anti-sedimentation expansion section. The bottom of the dense phase reaction zone is equipped with a gas distribution plate, and the upper side wall is equipped with a thermocouple, an overflow product discharge valve, and a pressure pulsation sensor. The anti-sedimentation expansion section is used to reduce the apparent flow rate of the gas phase and settle fine particles. Its top outlet is connected to the high-temperature cyclone separator of the gas-solid separation and circulation unit.

4. The system according to claim 3, characterized in that: The system also includes a central processing unit electrically connected to the pressure pulsation sensor and the material metering and feeding device; the central processing unit is used to acquire and process the bed pressure drop signal in the dense phase zone of the reactor in real time, and calculate the standard deviation σ of the pressure drop signal and the average particle circulation time. t ac The system assesses the tendency of bed agglomeration and loss of flow online, and achieves dynamic intervention against agglomeration by issuing closed-loop adjustment commands to the material metering and feeding device to replenish precursors.

5. The system according to claim 1, characterized in that: The mixed gas distribution system is connected to a gas thermal integrated distribution unit. The gas thermal integrated distribution unit’s inlet pipe is connected to the high-temperature flue gas pipe of the solid waste incinerator and the superheated steam pipe of the waste heat boiler. The gas thermal integrated distribution unit continuously mixes and produces a composite fluidized air source containing carbon dioxide, residual oxygen and superheated steam with a volume fraction of not less than 40%.

6. A method for online fluidized mineralization, encapsulation, and solidification of heavy metals in incinerator waste using the system described in claim 1, characterized in that, Includes the following steps: 1) The ash and slag pretreatment unit continuously crushes the bottom ash from the tail end of the solid waste incinerator to a particle size range of 0.5-2 mm, and introduces it together with the intercepted high-temperature fly ash into a multi-functional continuous pre-mineralization mixing screw device. In the screw device, aluminosilicate precursors, alkali activators and structure guiding agents are continuously added according to the formula. 2) By utilizing the sensible heat of ash slag in conjunction with external waste heat insulation, the material in the mixing screw device is continuously advanced and held for 15-30 minutes at a temperature of 80-250℃. This allows the alkali activator to partially melt and induce the kaolin to undergo a pre-mineralization reaction, transforming it into an active precursor. Simultaneously, the pre-mineralized material is continuously compacted at the screw discharge end to form a continuous and dense material seal. While maintaining the airtight isolation effect of the continuous and dense material seal, the pre-mineralized material is continuously transported to the fluidized bed reactor. 3) Fluidizing gas containing water vapor is introduced into the bottom of the fluidized bed reactor, and the apparent gas velocity of the bed is controlled at 0.6-1.0 m / s, maintaining the bed crystallization and reforming temperature at 700-750℃; the active precursor combines with the inherent chloride ions and / or sulfate ions in the ash and slag to undergo deep skeletal rearrangement, and is oriented to crystallize in situ on the surface of the bottom ash and fly ash particles to construct a matrix of sodalite group minerals and / or nepheline group minerals; during this crystallization process, the heavy metal ions released by the ash and slag upon heating replace the alkali metal ions in the crystal lattice through the isomorphic substitution mechanism, and are encapsulated in the cage-like crystal lattice cavity by long-term chemical bonding; 4) After the solid material of heavy metal lattice solidification is completed, it is continuously discharged from the overflow valve on the side of the fluidized bed reactor, and after being cooled by the slag cooler, it is directly transported and disposed of as a solid product.

7. The method according to claim 6, characterized in that: In step 3), the fluidized bed reactor has a dual-component synergistic fluidization field with different weights inside the bed. The high-temperature bottom ash crushed to 0.5-2 mm in step 1) serves as the first component of the fluidized bed, which is a heavy inert bed material to maintain stable bed heat capacity and gas-solid heat transfer. The fine fly ash and kaolin composite inclusions serve as the second component, which is a light fluidized material. High-frequency particle collisions and solid-solid mass transfer occur in the voids of the bottom ash bed material, and sodalite aggregates are generated on the surface of the bottom ash bed material particles and at independent crystallization sites.

8. The method according to claim 6, characterized in that: In step 3), the volume fraction of superheated steam in the fluidized mixed gas is strictly controlled at 40-60%, the volume fraction of oxygen is controlled at 3-10%, and the remainder is carbon dioxide and nitrogen from the incinerator flue gas. This creates a hydrothermal high-temperature mineralization microenvironment at atmospheric or near-atmospheric pressure, which inhibits the uncontrollable volatilization and diffusion of heavy metal ions at temperatures above 750°C.

9. The method according to claim 6, characterized in that: In step 1), the additive ratio is as follows: the aluminosilicate precursor is kaolin, the alkali activator is sodium hydroxide, and the structure directing agent is sodium chloride or sodium sulfate; the mass ratio of the aluminosilicate precursor, the alkali activator and the structure directing agent satisfies 1:(0.3-0.5):(0.1-0.2). By dynamically adjusting the mass feed rate of the additive, the Na / (Al+Si) molar ratio of the reaction system in the fluidized bed reactor is made to be 0.45-0.80, and the Al / Si molar ratio is made to be 0.80-1.

40.

10. The method according to claim 6, characterized in that, The system is equipped with a central processing unit (CPU); the CPU is used to acquire and process the bed pressure drop signal in the dense phase zone of the reactor in real time, and calculate the standard deviation σ of the pressure drop signal and the average particle circulation time t that passes through the average value. ac The system implements the following anti-caking dynamic intervention method during continuous operation: 1) The bed pressure drop signal in the dense phase reaction zone is continuously monitored online using a central processing unit. If the calculated standard deviation σ fluctuates abnormally, and the average particle circulation time... t ac When the set safety threshold is exceeded, it is determined that the local enrichment of fusible chlorides or sulfates in the reaction system leads to the risk of material agglomeration and clumping. 2) The central processing unit outputs adjustment commands to the frequency converter corresponding to the aluminosilicate precursor to increase the mass feeding rate of the aluminosilicate precursor, thereby increasing the instantaneous ratio of the mass flow rate of the aluminosilicate precursor to the mass flow rate of the ash. The incremental aluminosilicate precursor forms a dense protective coating layer on the surface of the precursor and the surface of the bed material particles, and reacts with free alkali metal ions in a solid phase to generate high-melting-point alkali metal aluminosilicate minerals. This reduces the content of low-melting-point liquid phase and weakens the liquid bridge adhesion between particles, preventing the fluidized bed from undergoing a defluidization chain reaction due to the stickiness of the ash surface.

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