Fly ash detoxification furnace slag aggregate making and remelting process in garbage incinerator
By injecting solid chlorine agents into the waste incinerator to treat fly ash, preparing slag aggregate, and burning it back into the furnace, the problems of land occupation and secondary pollution in fly ash disposal are solved, and efficient and economical resource utilization is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-04
- Publication Date
- 2026-04-03
AI Technical Summary
Existing fly ash disposal methods suffer from large land resource occupation, high risk of secondary pollution, and high long-term management costs. Resource utilization technologies such as high-temperature melting require the construction of additional dedicated disposal facilities. Co-processing in cement kilns has low reliability, high-temperature melting technology has poor economic efficiency, and by-products from water washing processes have poor sales channels.
Pretreatment is carried out in the waste incinerator by injecting chlorine-fixing agents, heavy metal fixatives, dioxin inhibitors and adsorption passivators. After collecting and mixing with water, slag aggregate intermediates are prepared and then burned back into the furnace. Combined with SCR denitrification and deacidification processes, the flue gas emissions are ensured to meet the standards.
It achieves efficient detoxification of fly ash, reduces land resource occupation and secondary pollution risks, improves the reliability and economy of resource-based disposal, reduces energy consumption and treatment costs, and the by-products can be used as building material raw materials.
Smart Images
Figure CN121782574A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a process for detoxifying fly ash in waste incinerators to produce slag aggregate for recycling, belonging to the field of waste incineration technology. Background Technology
[0002] With the acceleration of urbanization in my country, municipal solid waste incineration power generation has become a core means of solving the problem of garbage besieging cities. However, the fly ash produced during the incineration process is classified as HW18 hazardous waste because it is rich in heavy metals (Hg, Pb, Cd, etc.) and toxic and harmful substances such as dioxins.
[0003] Currently, fly ash disposal mainly involves solidification and stabilization followed by landfilling. However, this method suffers from problems such as large land resource consumption, high risk of secondary pollution, and high long-term management costs. Existing resource recovery technologies, including cement kiln co-processing, high-temperature melting, and water washing combined with non-fired building materials, require the construction of dedicated disposal facilities. Furthermore, cement kiln co-processing is limited by geographical distribution and operating rates, resulting in low reliability. High-temperature melting technology has energy consumption as high as 1500-2000 kWh / ton, making it uneconomical. Water washing processes require deep chloride removal, and the byproducts have poor market prospects. Based on this, the present invention provides a process for detoxifying fly ash in waste incinerators to produce slag aggregate for recycling. Summary of the Invention
[0004] The technical problems to be solved by this invention are: landfilling has a large land resource occupation, high risk of secondary pollution, and high long-term management costs; resource utilization technologies such as high-temperature melting require additional dedicated disposal facilities; cement kiln co-processing has low reliability; high-temperature melting technology has poor economic efficiency; and by-products from water washing processes have poor sales channels.
[0005] To address the aforementioned problems, this invention provides a process for detoxifying fly ash in waste incinerators to produce slag aggregate for recycling. The proposed technical solution includes the following steps:
[0006] S1: Pretreatment stage: Chlorine-fixing agent and heavy metal fixative are continuously sprayed into the observation hole of the waste incinerator grate to solidify chloride ions and heavy metals in fly ash. Dioxin inhibitor is sprayed into the secondary air inlet of the waste incinerator grate to inhibit the formation of dioxins. Adsorption and passivation agent is sprayed into the bag filter of the incinerator flue gas purification system to adsorb dioxins and further passivate heavy metals.
[0007] S2: Fly ash collection stage: Pre-treated and detoxified fly ash is collected by a bag filter. The heavy metals, dioxins and chloride ions in the fly ash are solidified or inhibited to meet the general solid waste standards.
[0008] S3: Slag aggregate preparation stage: The collected detoxified fly ash is mixed with adsorption and passivation agent and water. After being stirred evenly by a stirrer, it is sent to a briquetting machine to be pressed into shape to obtain slag aggregate intermediate.
[0009] S4: Recycling stage: The slag aggregate intermediate is sent to the high temperature zone above 850°C of the waste incinerator for recycling. During the combustion process, dioxins are almost completely decomposed, and the combustion products are collected and utilized as general solid waste.
[0010] Furthermore, in step S1, the addition time of the chlorine-fixing agent, dioxin inhibitor, and adsorption passivating agent is from 1 hour before ash collection to the end of ash collection, with a total duration of 3 hours.
[0011] Furthermore, in step S1, the solid chlorine agent is mainly composed of a mixture of aluminum oxide, silicon oxide, calcium oxide, iron oxide, magnesium oxide, and sodium oxide, with a particle size of 200-325 mesh.
[0012] Furthermore, in step S1, the heavy metal fixative is mainly composed of complex oxides of silicon dioxide, aluminum oxide, calcium oxide, and potassium oxide.
[0013] Furthermore, in step S1, the dioxin inhibitor is a weakly alkaline, pale yellow powder, and the main components of the dioxin inhibitor are sulfur, calcium carbonate, silicon dioxide, and aluminum oxide, with a particle size of 200-325 mesh.
[0014] Furthermore, in step S1, the adsorption passivating agent is an inorganic mineral with a magnesium aluminum silicate structure, and the main components of the adsorption passivating agent are aluminum oxide, silicon oxide, calcium oxide, iron oxide, and magnesium oxide, with a particle size of 200-325 mesh.
[0015] Furthermore, in step S3, the amount of water added is 8%-15% of the fly ash mass.
[0016] Furthermore, in step S4, during the re-combustion process, the furnace temperature is controlled above 850℃ and the residence time is ≥2 seconds, in conjunction with the SCR denitrification process and the dry + semi-dry + wet desulfurization process, to ensure that the flue gas meets emission standards.
[0017] The beneficial effects of this invention are:
[0018] This invention provides a process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, which can improve the stain resistance of cotton yarn. The process equipment for improving the stain resistance of cotton yarn has a simple structure, low energy consumption, and reduced costs. Attached Figure Description
[0019] Figure 1 This is a flow chart of the fly ash detoxification process in the waste incinerator of the present invention.
[0020] Figure 2 This is a flow chart of the fly ash to slag aggregate production process of the present invention.
[0021] Figure 3This is a table showing the results of the leaching toxicity test of fly ash samples according to the present invention. Detailed Implementation
[0022] The preferred embodiments of the present invention will now be described in detail.
[0023] This invention provides a process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, which includes the following steps:
[0024] S1: Pretreatment Stage: A chlorine-fixing agent and a heavy metal fixative are continuously sprayed through the observation port of the waste incinerator grate to solidify chloride ions and heavy metals in the fly ash. A dioxin inhibitor is sprayed at the secondary air inlet of the waste incinerator grate to inhibit dioxin formation. An adsorption passivating agent is sprayed before the bag filter of the incinerator flue gas purification system to adsorb dioxins and further passivate heavy metals. The chlorine-fixing agent, dioxin inhibitor, and adsorption passivating agent are added from 1 hour before ash removal until the end of ash removal, for a total duration of 3 hours. The main components of the chlorine-fixing agent are alumina, silicon dioxide, calcium oxide, iron oxide, magnesium oxide, and oxide. The sodium mixture, with a particle size of 200-325 mesh, reacts with chloride ions in fly ash at a combustion temperature of 600-800℃ to form Friedel's salt and calcium chlorosilicate salt; the heavy metal fixative is mainly composed of complex oxides of silicon dioxide, aluminum oxide, calcium oxide, and potassium oxide, which fix heavy metal ions such as lead and cadmium through surface adsorption, complexation reaction, and structural encapsulation to form stable aluminosilicate compounds, and can also prevent boiler coking; the dioxin inhibitor is a weakly alkaline pale yellow powder, and the main components of the dioxin inhibitor are sulfur, calcium carbonate, silicon dioxide, and aluminum oxide, with a particle size of 200-325 mesh. With a moisture content of less than 10%, it is uniformly dispersed in the furnace under the action of secondary air to inhibit the formation of dioxins; the adsorption passivating agent is an inorganic mineral with a magnesium aluminum silicate structure, which adsorbs dioxins and heavy metals, and can exchange magnesium ions with heavy metal ions to fix heavy metals into aluminosilicate stable substances. The main components of the adsorption passivating agent are aluminum oxide, silicon oxide, calcium oxide, iron oxide, and magnesium oxide, with a particle size of 200-325 mesh. Its complex chemical structure and mesoporous structure can fix soluble chlorine.
[0025] S2: Fly ash collection stage: Pre-treated and detoxified fly ash is collected by a bag filter. The heavy metals, dioxins and chloride ions in the fly ash are solidified or inhibited to meet the general solid waste standards.
[0026] S3: Slag Aggregate Preparation Stage: The collected detoxified fly ash is mixed with adsorption and passivation agent and water. After being stirred evenly by a stirrer, it is fed into a briquetting machine for pressing and molding to obtain slag aggregate intermediate. In step S3, the amount of water added is 8%-15% of the fly ash mass. The performance parameters of the slag aggregate intermediate meet the following requirements: particle size ≥ 98% residue rate through a 2.36mm square hole sieve, iron content < 2%, light floating matter content ≤ 0.2%, moisture content ≤ 18%, cylinder compressive strength ≥ 3.2MPa, and chloride ion content ≤ 9.61×10⁻⁶. 3 mg / kg;
[0027] S4: Recycled treatment stage: The intermediate slag aggregate is sent to the high-temperature zone above 850℃ in the waste incinerator for recycled combustion. During the combustion process, dioxins are almost completely decomposed, and the combustion products are collected and utilized as general solid waste. During the recycled combustion process, the furnace temperature is controlled above 850℃ and the residence time is ≥2 seconds. Combined with SCR denitrification process and dry + semi-dry + wet desulfurization process, the flue gas is ensured to meet emission standards.
[0028] Example 1
[0029] Xuchang Wangneng Environmental Energy Co., Ltd.'s 750-ton / day waste incinerator grate furnace
[0030] Pretreatment stage: At the observation holes of the three 750-ton / day waste incinerator grate furnaces of Xuchang Wangneng Environmental Energy Co., Ltd., solid chlorine agent and heavy metal fixative are continuously sprayed into the grate furnace at a rate of 120 kg / batch. Dioxin inhibitor is sprayed into the secondary air inlet pipe of the same waste incinerator grate furnace at a rate of 6 kg / batch. Adsorption and passivation agent is sprayed into the horizontal flue before the bag filter at a rate of 75 kg / batch. The addition time is from 1 hour before ash removal to the end of ash removal.
[0031] Fly ash collection stage: Detoxified fly ash is collected by bag filter, with a daily collection volume of 35 kg. After testing, the dioxin content and heavy metal leaching concentration in the fly ash meet the GB 5085.3-2007 standard.
[0032] Slag aggregate preparation stage: 35kg of detoxified fly ash, 75kg of adsorption and passivation agent, and 4.2kg of water are mixed and stirred for 15 minutes. The mixture is then fed into a briquetting machine and pressed into shape under a pressure of 10MPa to obtain 40kg of slag aggregate intermediate.
[0033] Recycled processing stage: The intermediate slag aggregate is sent into the 850℃ high-temperature zone of the incinerator and held for 2.5 seconds for recycling. During the combustion process, the flue gas is treated by SCR denitrification process and dry + semi-dry + wet deacidification process to ensure that the flue gas meets the emission standards.
[0034] In summary, after source detoxification, the fly ash of this invention exhibits a dioxin degradation rate exceeding 99%, heavy metal leaching concentrations below national standard limits, and chloride ion removal rates exceeding 98%. Recycling completely eliminates the risk of secondary dioxin formation, resulting in significant environmental benefits. The calcium, silicon, aluminum, and other mineral components in the fly ash are fully utilized after treatment, and the recycled combustion products can be used as building material raw materials or roadbed materials. This addresses the problems of large land resource occupation, high secondary pollution risk, and high long-term management costs associated with landfilling. Compared to resource recovery technologies such as high-temperature melting, the reliability of disposal is greatly improved, energy consumption is reduced by more than 60%, and economic efficiency is excellent. Byproducts have smooth sales channels, and no additional dedicated disposal facilities are required; processing can be achieved using existing waste incinerators, reducing processing costs.
[0035] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.
Claims
1. A process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, characterized by: Includes the following steps: S1: Pretreatment stage: Chlorine-fixing agent and heavy metal fixative are continuously sprayed into the observation hole of the waste incinerator grate to solidify chloride ions and heavy metals in fly ash. Dioxin inhibitor is sprayed into the secondary air inlet of the waste incinerator grate to inhibit the formation of dioxins. Adsorption and passivation agent is sprayed into the bag filter of the incinerator flue gas purification system to adsorb dioxins and further passivate heavy metals. S2: Fly ash collection stage: Pre-treated and detoxified fly ash is collected by a bag filter. The heavy metals, dioxins and chloride ions in the fly ash are solidified or inhibited to meet the general solid waste standards. S3: Slag aggregate preparation stage: The collected detoxified fly ash is mixed with adsorption and passivation agent and water. After being stirred evenly by a stirrer, it is sent to a briquetting machine to be pressed into shape to obtain slag aggregate intermediate. S4: Recycling stage: The slag aggregate intermediate is sent to the high temperature zone above 850°C of the waste incinerator for recycling. During the combustion process, dioxins are almost completely decomposed, and the combustion products are collected and utilized as general solid waste.
2. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S1, the solid chlorine agent, dioxin inhibitor, and adsorption passivating agent are added from 1 hour before ash collection to the end of ash collection, for a total duration of 3 hours.
3. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S1, the solid chlorine agent is mainly composed of a mixture of aluminum oxide, silicon oxide, calcium oxide, iron oxide, magnesium oxide and sodium oxide, with a particle size of 200-325 mesh.
4. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S1, the heavy metal fixative is mainly composed of complex oxides of silicon dioxide, aluminum oxide, calcium oxide, and potassium oxide.
5. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S1, the dioxin inhibitor is a weakly alkaline, pale yellow powder. The main components of the dioxin inhibitor are sulfur, calcium carbonate, silicon dioxide, and aluminum oxide, with a particle size of 200-325 mesh.
6. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S1, the adsorption passivating agent is an inorganic mineral with a magnesium aluminum silicate structure. The main components of the adsorption passivating agent are aluminum oxide, silicon oxide, calcium oxide, iron oxide, and magnesium oxide, with a particle size of 200-325 mesh.
7. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S3, the amount of water added is 8%-15% of the fly ash mass.
8. The process for detoxifying fly ash in a waste incinerator to produce slag aggregate for recycling, as described in claim 1, is characterized in that: In step S4, during the re-combustion process, the furnace temperature is controlled above 850℃ and the residence time is ≥2 seconds. This is combined with the SCR denitrification process and the dry + semi-dry + wet desulfurization process to ensure that the flue gas meets emission standards.