A method for waste incineration fly ash segmented hydrothermal harmless disposal and high-value utilization

Abstract

The present application relates to a kind of waste incineration fly ash segmented type hydrothermal harmless disposal and high-value utilization method comprising the following steps: S1, fly ash is added to water and is pretreated, and water washing fly ash and washing liquid are separated;S2, bottom ash and soluble aluminate are added to the washing liquid, after subcritical hydrothermal reaction, and the solid phase material containing sodalite and hydrothermal reaction liquid are separated;S3, the washing fly ash, oxidizing agent is added to the hydrothermal reaction liquid, and low-temperature ultrasonic hydrothermal reaction is carried out, then the solid phase material containing sodalite and alkali are added, and microwave hydrothermal reaction is carried out, and hydrothermal solid phase product is separated;S4, the hydrothermal solid phase product is added to polluted water body and is removed pollutant.The present application removes the pollutant in fly ash efficiently, and can be further applied to the pollutant removal in wastewater, can provide technical support for large-scale harmless disposal and high-value utilization of waste incineration fly ash.

Description

Technical Field

[0001] This invention relates to the field of harmless disposal and resource utilization of hazardous solid waste, and in particular to a method for the safe disposal and resource reuse of fly ash from waste incineration. Background Technology

[0002] With the continuous development of urbanization in China, the amount of municipal solid waste generated is increasing at a rate of 8-10% annually. According to data from the "China Statistical Yearbook 2021," by 2020, the total amount of municipal solid waste collected nationwide had reached 235.117 million tons, of which 146.076 million tons were treated using incineration technology, accounting for over 60%. Although waste incineration technology has advantages such as volume reduction, harmlessness, and resource recovery, it produces bottom ash (15-25% of the total incinerated waste) and fly ash (3-5% of the total). Bottom ash has a large particle size (0.02-10mm), is loose and porous, has high water absorption, and low density, making it a typical bulk solid waste. It is rich in Si, Al, Ca, and other major constituent elements of aluminosilicate minerals and can be used as raw materials for the synthesis of zeolites, Katoite, sodalite, and other aluminosilicate minerals. In contrast, fly ash has a small particle size (about 100 μm), is lightweight, and contains a variety of toxic heavy metals (such as Pb, Zn, Cu, Cd, Cr, Ni, etc.), as well as high concentrations of soluble chlorine, dioxins, chlorobenzenes, and other volatile organic compounds. It is a typical hazardous waste, and if not properly disposed of, it will cause great harm to the environment and human health.

[0003] To remove toxic substances from waste incineration fly ash, reduce its environmental harm, and achieve its resource reuse, technologies such as solidification / stabilization, heat treatment, and hydrothermal treatment are commonly used to render fly ash harmless. Solidification / stabilization technology uses chemical agents or inorganic / organic solidifying agents to form a solidified body with the bottom ash or fly ash, reducing the specific surface area and permeability of the fly ash, thereby achieving the goal of harmless disposal. The resulting cementitious materials, geopolymers, and cementitious solids can be used as building materials. However, solidification / stabilization technologies are difficult to effectively treat and stabilize heavy metals such as lead and hexavalent chromium, as well as organic pollutants such as dioxins, in incineration fly ash. Thermal treatment involves heating the fly ash to a molten state in a high-temperature environment (700-2200℃) and then rapidly cooling it to form a dense and stable glassy slag, permanently sealing toxic and harmful substances within it. Materials such as ceramsite, rock wool, and foam ceramics formed by high-temperature melting can be used in road construction and fireproofing materials. However, excessively high melting temperatures may cause heavy metal volatilization, resulting in secondary pollution. Hydrothermal treatment utilizes elements such as calcium, silicon, and aluminum in fly ash to form minerals that can stabilize heavy metals under hydrothermal conditions. At the same time, by taking advantage of the abrupt changes in the viscosity, density, diffusion coefficient, and mass transfer properties of water under high temperature and high pressure, it effectively improves the miscibility between water and organic matter, thereby achieving the degradation of organic pollutants such as dioxins.

[0004] Although hydrothermal technology offers milder treatment conditions, can simultaneously stabilize multiple heavy metals, and produces products with no significant volume increase compared to the aforementioned technologies, it still suffers from lower removal rates of soluble chlorine, lower degradation and detoxification efficiency of organic pollutants such as dioxins, and lower stabilization efficiency of heavy metal lead. Amphoteric heavy metals such as lead and zinc are prone to migrate into the hydrothermal waste liquid, which can easily cause secondary pollution, and the products have low resource value.

[0005] In conclusion, it is necessary to develop a new technical solution to address the shortcomings of existing technologies. Summary of the Invention

[0006] Based on this, the present invention provides a segmented hydrothermal harmless treatment and high-value utilization method for waste incineration fly ash. This method can effectively stabilize heavy metals in fly ash, remove organic pollutants such as dioxins, and transform waste incineration fly ash into an adsorbent with high resource attributes, which can be further applied to the removal of pollutants in industrial wastewater or domestic wastewater. This method can provide technical support for the large-scale harmless treatment and high-value utilization of waste incineration fly ash.

[0007] One objective of this invention is to provide a method for the staged hydrothermal harmless treatment and high-value utilization of waste incineration fly ash, the method comprising the following steps:

[0008] S1. Add fly ash to water for pre-washing treatment, and separate the washed fly ash and washing liquid.

[0009] S2. Add the base ash and soluble aluminate to the washing solution, and after subcritical hydrothermal reaction, separate the sodalite-containing solid phase and the hydrothermal reaction solution.

[0010] S3. Add the water-washed fly ash and oxidant to the hydrothermal reaction solution and carry out a low-temperature ultrasonic hydrothermal reaction. Then add the sodalite-containing solid phase and alkali and carry out a microwave hydrothermal reaction to separate and obtain the hydrothermal solid phase product (adsorbent).

[0011] S4. The hydrothermal solid product is added to the polluted water body to remove pollutants.

[0012] Furthermore, in step S1, the liquid-to-solid ratio of the water and fly ash is 5-50 mL / g.

[0013] Furthermore, in step S1, the water washing pretreatment temperature is 20-50℃, the treatment time is 10-180min, and the oscillation speed is 100-1000r / min.

[0014] Preferably, in step S1, the liquid-to-solid ratio is 10-30 mL / g, more preferably 20 mL / g; the treatment temperature is 25°C; the shaking speed is 200-500 r / min, more preferably 300 r / min; and the shaking time is 10-240 min, more preferably 30-90 min, and even more preferably 60 min.

[0015] In step S2, the subcritical hydrothermal reaction is carried out at a temperature of 100-280℃ and for a time of 30-240 min.

[0016] Further, in step S2, the base ash and soluble aluminate are added to the washing solution to make the molar ratio of Si to Al 0.5-2.5:1.

[0017] Preferably, in step S2, the liquid-to-solid ratio is 3-20 mL / g, more preferably 5-15 mL / g, and even more preferably 10:1 mL / g; soluble aluminate is added to adjust the molar ratio of Si to Al to 0.75-2.0:1, and even more preferably 1.5:1.

[0018] Furthermore, in step S3, the reaction temperature of the low-temperature ultrasonic hydrothermal reaction is 50-150℃, the reaction time is 10-240 min, the stirring speed is 200-500 r / min, and the ultrasonic frequency is 20-30 kHz.

[0019] Furthermore, in step S3, the reaction temperature of the microwave hydrothermal reaction is 100-220℃, and the reaction time is 10-240 min.

[0020] Furthermore, in step S3, the oxidant is selected from one or more of hydrogen peroxide and sodium percarbonate.

[0021] Further, in step S3, the mass ratio of the water-washed fly ash to the sodalite-containing solid phase is 100:3-15.

[0022] Preferably, in step S3, the low-temperature ultrasonic hydrothermal reaction temperature is 70-130℃, more preferably 120℃; the ultrasonic frequency is 22-28KHz, more preferably 25KHz; the stirring speed is 250r / min; the reaction time is 30-180min, more preferably 120min; the amount of hydrogen peroxide added is 3.0-25.0% of the volume of the hydrothermal reaction liquid, more preferably 10.0-20.0%, and even more preferably 15.0%; the amount of sodium percarbonate added is 1.0-10.0% of the water-washed fly ash, more preferably 3.0-8.0%, and even more preferably 5.0%.

[0023] Preferably, in step S3, the temperature of the microwave hydrothermal reaction is 100-200℃, more preferably 120-180℃, and even more preferably 150℃; the reaction time is 30-180 min, more preferably 120 min; and the amount of sodalite solid is 5.0-10.0% of the water-washed fly ash, more preferably 8.0%.

[0024] Furthermore, in step S4, the pH of the polluted water body is 2-10.

[0025] Furthermore, the pollutant is an organic pollutant or a heavy metal, wherein the organic pollutant is one or more of organophosphorus pesticides, anilines, and phenols; and the heavy metal is Pb. 2+ Cr 3+ Cr 6+ Cd 2+ Zn 2+ Ni 2+ One or more of them.

[0026] Figure 1 This is a process flow diagram of the present invention.

[0027] The present invention has the following beneficial effects:

[0028] 1. This invention can simultaneously achieve efficient removal of chlorine from waste incineration fly ash, effective stabilization of heavy metals, degradation and detoxification of organic pollutants such as dioxins, and high-value utilization of waste incineration fly ash and bottom ash.

[0029] 2. The first stage of this invention, water washing pretreatment, can efficiently remove chloride salts from fly ash. Soluble chlorine in the washing liquid can be removed using subcritical hydrothermal technology by adding sodalite synthesized from waste incineration bottom ash and sodium aluminate. The synthesized sodalite solid can be further used for the degradation and detoxification of dioxins and the stabilization of heavy metals in fly ash. The second stage, low-temperature ultrasonic hydrothermal reaction, not only helps dissolve elements such as Ca, Si, and Al in fly ash but also achieves the degradation and detoxification of dioxins. The oxidizing atmosphere provided by the oxidant helps degrade organic pollutants such as dioxins in fly ash. The ultrasonic cavitation effect caused by ultrasound can generate local high temperatures (up to 5000K) and local high pressures (up to 50MPa) in a very small space, accompanied by strong shock waves and microjets with speeds up to 100m / s. This not only promotes the rapid dissolution of Ca, Si, and Al elements in fly ash but also causes water molecules within the bubbles to split into ·OH and ·OH groups. Strong oxidizing free radicals such as HO2 and H2O2, along with the instantaneous high temperature and pressure, may also promote supercritical water oxidation reactions. These strong oxidizing substances act directly and indirectly on dioxin-like organic pollutants in fly ash, achieving efficient degradation of dioxin-like organic pollutants. The high temperature and high pressure conditions of microwave-assisted hydrothermal treatment used in the third stage can further promote the rapid dissolution, precipitation, and crystallization of elements such as Ca, Si, and Al in the washed fly ash. The added solid phase containing sodalite, synthesized by subcritical hydrothermal treatment of the bottom ash, can provide solid nuclei for crystallizing minerals, promote mineral crystallization, control the crystallization type of minerals, increase the yield of crystallizing minerals, and rapidly and efficiently form aluminosilicate minerals with the ability to stabilize heavy metals in fly ash, achieving deep dechlorination of fly ash. The solid products after hydrothermal treatment can also be used as adsorbents for the removal of pollutants in industrial or domestic wastewater, achieving a major breakthrough in the harmless treatment and high-value utilization of waste incineration fly ash.

[0030] 3. Compared with other methods for the harmless treatment of fly ash from waste incineration, the technical solution of this invention can not only achieve efficient removal of toxic substances from fly ash, but also is simple to operate, low in cost, energy-saving and environmentally friendly. It can also convert fly ash into high-value products, with significant environmental and economic advantages and broad market application prospects. Attached Figure Description

[0031] Figure 1 This is a process flow diagram of the present invention.

[0032] Figure 2 The phase composition analysis (XRD) of the waste incineration fly ash before treatment in Example 1 of the present invention, the sodalite-containing solid phase in step S2, and the final hydrothermal solid phase product in step S3 are shown.

[0033] Figure 3The phase composition analysis (XRD) of the waste incineration fly ash before treatment in Example 2 of the present invention, the sodalite-containing solid phase in step S2, and the final hydrothermal solid phase product in step S3 are shown.

[0034] Figure 4 The phase composition analysis (XRD) of the waste incineration fly ash before treatment in Example 3 of the present invention, the sodalite-containing solid phase in step S2, and the final hydrothermal solid phase product in step S3. Detailed Implementation

[0035] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0036] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0037] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0038] The hydrogen peroxide concentration in this embodiment of the invention is 30.0 wt.%.

[0039] Example 1

[0040] In this implementation case, the fly ash from waste incineration is collected from the bottom ash and fly ash produced by incinerating municipal solid waste in a grate furnace. The fly ash contains soluble chlorine (Cl). -The toxicity level was 29600 mg / kg, and the dioxin toxicity equivalent was 38.12 TEQ μg / g; the leaching method adopted was the sulfuric acid and nitric acid method (HJ / T) for leaching toxicity of solid waste. Heavy metal leaching toxicity tests were conducted on fly ash according to standard 299-2007. The concentrations of heavy metals in the leachate were: Zn: 4.30 mg / L, Pb: 5.47 mg / L, Cu: 3.62 mg / L, Cd: 0.48 mg / L, Cr: 1.46 mg / L, Ni: 0.26 mg / L. The heavy metal leaching toxicity tests were also conducted on fly ash using the acetic acid buffer solution method (HJ / T300-2007), and the concentrations of heavy metals in the leachate were: Zn: 42.38 mg / L, Pb: 5.37 mg / L, Cu: 30.26 mg / L, Cd: 2.42 mg / L, Cr: 2.71 mg / L, Ni: 1.18 mg / L.

[0041] A method for staged hydrothermal harmless treatment and high-value utilization of fly ash from waste incineration includes the following steps:

[0042] S1. Grind the fly ash to be treated to make its particle size below 100μm. Accurately weigh 100g of the ground waste incineration fly ash and add it to deionized water at a liquid-solid ratio of 10mL / g. After mixing evenly, a mixed slurry is obtained. The first stage of water washing pretreatment is carried out at a temperature of 30℃ and a shaking speed of 300r / min for 60min. After the water washing is completed, the mixed slurry is centrifuged to separate the water-washed fly ash and water washing liquid. The water-washed fly ash is dried in an oven at 105±5℃ for 8h.

[0043] S2. Grind the bottom ash from waste incineration to make its particle size below 100μm. Accurately weigh 100g of the ground bottom ash, add sodium aluminate, and adjust the theoretical molar ratio of Si to Al to 1.0:1. Add the mixture of bottom ash and sodium aluminate to the washing solution at a liquid-to-solid ratio of 5mL / g. After stirring evenly, transfer it to a subcritical hydrothermal reactor and react at 220℃ for 30min. Centrifuge to separate the solid product and the hydrothermal reaction solution. Dry the solid product in an oven at 105±5℃ for 8h to obtain a solid phase containing sodalite.

[0044] S3. Add the water-washed fly ash and sodium percarbonate to the hydrothermal reaction solution at a liquid-to-solid ratio of 10 mL / g. The amount of sodium percarbonate added is 3.0% of the mass fraction of the water-washed fly ash. After stirring and mixing evenly, transfer to a low-temperature ultrasonic hydrothermal reactor. Carry out the second stage of low-temperature ultrasonic hydrothermal reaction at a temperature of 80℃, an ultrasonic frequency of 22 kHz, and a stirring speed of 300 r / min. The reaction time is 120 min.

[0045] After the low-temperature ultrasonic hydrothermal reaction is completed, the reactor is naturally cooled to room temperature. The obtained low-temperature ultrasonic hydrothermal slurry is transferred to a microwave-assisted hydrothermal reactor. A solid phase containing sodalite with a mass fraction of 5.0% of water-washed fly ash is added, and then NaOH is added to adjust the NaOH content to 0.7 mol / L. The third stage of microwave-assisted hydrothermal reaction is carried out at a temperature of 120℃ for 120 min. After the reaction is completed, the reactor is naturally cooled to room temperature. The solid phase product and hydrothermal waste liquid are separated. The solid phase product is placed in an oven at 105±5℃ and dried for 8 h to obtain the hydrothermal solid phase product.

[0046] S4. The hydrothermal solid product is added to a copper sulfate solution (300 mg / L) at a liquid-to-solid ratio of 100 mL / g. The pH is adjusted to 3 with concentrated nitric acid. The mixture is shaken at 25°C and 300 r / min for 2 h in a constant temperature shaker. The solid-liquid mixture is separated by centrifugation and filtered through a 0.45 μm filter membrane to obtain a solution sample.

[0047] Figure 2 The XRD analysis of the phase composition of the fly ash from waste incineration before treatment in Example 1 of this invention, the XRD analysis of the phase composition of the sodalite-containing solid phase obtained by the hydrothermal reaction of waste incineration bottom ash in step S2, and the XRD analysis of the phase composition of the final hydrothermal solid phase product obtained after the low-temperature ultrasonic hydrothermal reaction in step S3 are as follows.

[0048] Soluble chlorine in the samples was determined using ion chromatography. Heavy metal leaching toxicity tests were conducted on the hydrothermal solid-phase products according to the standards "Solid Waste Leaching Toxicity Leaching Method: Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) and "Solid Waste Leaching Toxicity Leaching Method: Acetic Acid Buffer Solution Method" (HJ / T300-2007). The concentration of heavy metals in the leachate and hydrothermal waste liquid was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The dioxin content in the hydrothermal solid-phase products was analyzed using high-resolution gas chromatography / high-resolution mass spectrometry (HRGC / MS). Cation exchange capacity and heavy metal adsorption capacity tests were performed on the hydrothermal solid-phase products.

[0049] After treatment using the process described in this embodiment, the soluble chlorine in the hydrothermal solid product was reduced to 23.22 mg / kg. The heavy metal leaching concentrations in the leachate obtained using the "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) were as follows: Zn: 0.162 mg / L, Pb: 0.176 mg / L, Cu: 0.261 mg / L, Cd: 0.038 mg / L, Cr: 0.026 mg / L, Ni: 0.011 mg / L. The concentrations obtained using the "Solid Waste Leaching Toxicity Leaching Method - Acetic Acid Buffer Solution Method" (HJ / T 300- In 2007, the leaching concentrations of heavy metals in the leachate used for heavy metal toxicity tests were: Zn: 7.62 mg / L, Pb: 0.216 mg / L, Cu: 5.61 mg / L, Cd: 0.126 mg / L, Cr: 0.226 mg / L, Ni: 0.071 mg / L; the heavy metal concentrations in the hydrothermal wastewater were: Zn: 0.212 mg / L, Pb: 0.116 mg / L. Cu: 0.121 mg / L, Cd: 0.026 mg / L, Cr: 0.016 mg / L, Ni: 0.011 mg / L; Therefore, after the fly ash from municipal solid waste incineration is treated using the process of this invention, the leaching concentrations of various heavy metals in the fly ash are not only lower than the values ​​specified in the "Identification Standard for Hazardous Waste—Leaching Toxicity Identification" (GB5085.3-2007), but also meet the values ​​specified in the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2008). Furthermore, the content of various heavy metals in the hydrothermal waste liquid is extremely low, indicating that the heavy metals are effectively stabilized during the hydrothermal reaction process and do not migrate to the hydrothermal waste liquid, thus preventing secondary pollution. The dioxin toxicity equivalent is reduced to 1.93 TEQ μg / kg, a reduction of 94.96%. The solid product obtained after treatment using the process of this embodiment has excellent adsorption performance, with Cu adsorption within 120 minutes. 2+ The removal rate was 90.27%, and the concentration was reduced to 1.23 mg / L, showing promising application prospects as an adsorbent for resource recycling.

[0050] Example 2

[0051] In this implementation case, the fly ash from waste incineration is collected from the bottom ash and fly ash produced by fluidized bed incineration of municipal solid waste. The fly ash contains soluble chlorine (Cl). -The toxicity level was 30620 mg / kg, and the dioxin toxicity equivalent was 46.28 TEQ μg / g; the leaching method adopted was the sulfuric acid and nitric acid method (HJ / T) for leaching toxicity of solid waste. Heavy metal leaching toxicity tests were conducted on fly ash according to standard 299-2007. The concentrations of heavy metals in the leachate were: Zn: 7.27 mg / L, Pb: 4.14 mg / L, Cu: 5.25 mg / L, Cd: 0.54 mg / L, Cr: 1.21 mg / L, Ni: 0.45 mg / L. The heavy metal leaching toxicity tests were also conducted on fly ash using the acetic acid buffer solution method (HJ / T300-2007), and the concentrations of heavy metals in the leachate were: Zn: 57.63 mg / L, Pb: 7.26 mg / L, Cu: 37.16 mg / L, Cd: 1.62 mg / L, Cr: 1.90 mg / L, Ni: 1.03 mg / L.

[0052] A method for staged hydrothermal harmless treatment and high-value utilization of fly ash from waste incineration includes the following steps:

[0053] S1. Grind the fly ash to be treated to make its particle size less than 100μm. Accurately weigh 100g of the ground waste incineration fly ash and add it to deionized water at a liquid-solid ratio of 20mL / g. After mixing evenly, a mixed slurry is obtained. The first stage of water washing pretreatment is carried out at a temperature of 25℃ and a shaking speed of 300r / min for 60min. After the water washing is completed, the mixed slurry is centrifuged to separate the water-washed fly ash and water washing liquid. The water-washed fly ash is dried in an oven at 105±5℃ for 8h.

[0054] S2. Grind the bottom ash from waste incineration to make its particle size below 100μm. Accurately weigh 100g of the ground bottom ash, add sodium aluminate, and adjust the theoretical molar ratio of Si to Al to 1.5:1. Add the mixture of bottom ash and sodium aluminate to the washing solution at a liquid-to-solid ratio of 10mL / g. After stirring evenly, transfer it to a subcritical hydrothermal reactor and react at 280℃ for 30min. Centrifuge to separate the solid product and the hydrothermal reaction solution. Dry the solid product in an oven at 105±5℃ for 8h to obtain a solid phase containing sodalite.

[0055] S3. The water-washed fly ash is added to the hydrothermal reaction liquid at a liquid-to-solid ratio of 10 mL / g, and then hydrogen peroxide is added. The amount of hydrogen peroxide added is 15.0% of the volume of the hydrothermal reaction liquid. After stirring and mixing evenly, it is transferred to a low-temperature ultrasonic hydrothermal reactor. The second stage of low-temperature ultrasonic hydrothermal reaction is carried out under the conditions of temperature, ultrasonic frequency and stirring speed of 120℃, 25KHz and 250r / min respectively, and the reaction time is 120min.

[0056] After the low-temperature ultrasonic hydrothermal reaction is completed, the reactor is naturally cooled to room temperature. The obtained low-temperature ultrasonic hydrothermal slurry is transferred to a microwave-assisted hydrothermal reactor. A solid phase containing sodalite with a mass fraction of 8.0% of water-washed fly ash is added, and then NaOH is added to adjust the NaOH content to 1.0 mol / L. The third stage of microwave-assisted hydrothermal reaction is carried out at a temperature of 150℃ for 120 min. After the reaction is completed, the reactor is naturally cooled to room temperature. The solid phase product and hydrothermal waste liquid are separated. The solid phase product is placed in an oven at 105±5℃ and dried for 8 h to obtain the hydrothermal solid phase product.

[0057] S4. The hydrothermal solid product is added to a phenol-copper solution (200 mg / L) at a liquid-to-solid ratio of 100 mL / g. The pH is adjusted to 3 with concentrated nitric acid. The mixture is shaken at 25°C and 300 r / min for 2 h in a constant temperature shaker. The solid-liquid mixture is separated by centrifugation and filtered through a 0.45 μm filter membrane to obtain a solution sample.

[0058] Figure 3 The XRD analysis results are as follows: for the phase composition analysis of the fly ash from waste incineration before treatment in Example 2 of this invention, the XRD analysis results of the sodalite-containing solid phase obtained by the hydrothermal reaction of waste incineration bottom ash in step S2, and the XRD analysis results of the final hydrothermal solid phase product obtained after the low-temperature ultrasonic hydrothermal reaction in step S3.

[0059] Soluble chlorine in the samples was determined using ion chromatography. Heavy metal leaching toxicity tests were conducted on the hydrothermal solid-phase products according to the standards "Solid Waste Leaching Toxicity Leaching Method: Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) and "Solid Waste Leaching Toxicity Leaching Method: Acetic Acid Buffer Solution Method" (HJ / T300-2007). The concentration of heavy metals in the leachate and hydrothermal waste liquid was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The dioxin content in the hydrothermal solid-phase products was analyzed using high-resolution gas chromatography / high-resolution mass spectrometry (HRGC / MS). Cation exchange capacity and heavy metal adsorption capacity tests were performed on the hydrothermal solid-phase products.

[0060] After treatment using the process described in this embodiment, the soluble chlorine in the fly ash was reduced to 35.66 mg / kg. The heavy metal leaching concentrations in the leachate, tested using the sulfuric acid-nitric acid method (HJ / T 299-2007) for heavy metal leaching toxicity testing of solid waste, were: Zn: 0.251 mg / L, Pb: 0.212 mg / L, Cu: 0.436 mg / L, Cd: 0.022 mg / L, Cr: 0.036 mg / L, Ni: 0.018 mg / L. The heavy metal leaching concentrations in the leachate, tested using the acetic acid buffer solution method (HJ / T300-2007) for heavy metal leaching toxicity testing of solid waste, were... The concentrations of the following substances were: Zn: 6.56 mg / L, Pb: 0.130 mg / L, Cu: 4.52 mg / L, Cd: 0.097 mg / L, Cr: 0.314 mg / L, Ni: 0.023 mg / L; the concentrations of heavy metals in the hydrothermal waste liquid were: Zn: 0.412 mg / L, Pb: 0.215 mg / L, Cu: 0.213 mg / L, Cd: 0.011 mg / L, Cr: 0.006 mg / L, Ni: 0.009 mg / L. Therefore, after the fly ash from municipal solid waste incineration is treated using the process of this invention, the leaching concentrations of various heavy metals in the fly ash are not only lower than the values ​​specified in the "Identification Standard for Hazardous Waste—Leaching Toxicity Identification" (GB5085.3-2007), but also meet the values ​​specified in the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2008). Furthermore, the content of various heavy metals in the hydrothermal waste liquid is extremely low, indicating that the heavy metals are effectively fixed in the fly ash during the hydrothermal reaction process, rather than migrating to the hydrothermal waste liquid on a large scale. The dioxin toxicity equivalent is reduced to 2.16 TEQ μg / kg, a reduction of 95.33%. The solid-phase product obtained after treatment using the process of this embodiment has excellent adsorption performance, with Cu adsorption within 120 minutes. 2+ The removal rate was 90.27%, and the concentration was reduced to 10.3 mg / L.

[0061] Example 3

[0062] In this implementation case, the fly ash from waste incineration is collected from the bottom ash and fly ash produced by incinerating municipal solid waste in a grate furnace. The fly ash contains soluble chlorine (Cl). -The toxicity level was 28350 mg / kg, and the dioxin toxicity equivalent was 26.12 TEQ μg / g; the leaching method adopted was the sulfuric acid and nitric acid method (HJ / T) for leaching toxicity of solid waste. Heavy metal leaching toxicity tests were conducted on fly ash according to standard 299-2007. The concentrations of heavy metals in the leachate were: Zn: 3.81 mg / L, Pb: 4.26 mg / L, Cu: 2.16 mg / L, Cd: 0.41 mg / L, Cr: 1.26 mg / L, Ni: 0.19 mg / L. The heavy metal leaching toxicity tests were also conducted on fly ash using the acetic acid buffer solution method (HJ / T300-2007), and the concentrations of heavy metals in the leachate were: Zn: 34.26 mg / L, Pb: 6.21 mg / L, Cu: 27.32 mg / L, Cd: 1.40 mg / L, Cr: 2.12 mg / L, Ni: 0.89 mg / L.

[0063] A method for staged hydrothermal harmless treatment and high-value utilization of fly ash from waste incineration includes the following steps:

[0064] S1. Grind the fly ash to be treated to make its particle size less than 100μm. Accurately weigh 100g of the ground waste incineration fly ash and add it to deionized water at a liquid-solid ratio of 20mL / g. After mixing evenly, a mixed slurry is obtained. The first stage of water washing pretreatment is carried out at a temperature of 40℃ and a shaking speed of 200r / min for 180min. After the water washing is completed, the mixed slurry is centrifuged to separate the water-washed fly ash and the water washing liquid. The water-washed fly ash is dried in an oven at 105±5℃ for 8h.

[0065] S2. Grind the bottom ash from waste incineration to make its particle size below 100μm. Accurately weigh 100g of the ground bottom ash, add sodium aluminate, and adjust the theoretical molar ratio of Si to Al to 1.25:1. Add the mixture of bottom ash and sodium aluminate to the washing solution at a liquid-to-solid ratio of 15mL / g. After stirring evenly, transfer it to a subcritical hydrothermal reactor and react at 180℃ for 240min. Centrifuge to separate the solid product and the hydrothermal reaction solution. Dry the solid product in an oven at 105±5℃ for 8h to obtain a solid phase containing sodalite.

[0066] S3. The water-washed fly ash is added to the hydrothermal reaction liquid at a liquid-to-solid ratio of 20 mL / g, and then hydrogen peroxide is added. The amount of hydrogen peroxide added is 15.0% of the volume of the hydrothermal reaction liquid. After stirring and mixing evenly, it is transferred to a low-temperature ultrasonic hydrothermal reactor. The second stage of low-temperature ultrasonic hydrothermal reaction is carried out under the conditions of temperature, ultrasonic frequency and stirring speed of 150℃, 20KHz and 200r / min respectively, and the reaction time is 120min.

[0067] After the low-temperature ultrasonic hydrothermal reaction is completed, the reactor is naturally cooled to room temperature. The obtained low-temperature ultrasonic hydrothermal slurry is transferred to a microwave-assisted hydrothermal reactor. A solid phase containing sodalite with a mass fraction of 15.0% of water-washed fly ash is added, and then NaOH is added to adjust the NaOH content to 1.5 mol / L. The third stage of microwave-assisted hydrothermal reaction is carried out at a temperature of 150℃ for 120 min. After the reaction is completed, the reactor is naturally cooled to room temperature. The solid phase product and hydrothermal waste liquid are separated. The solid phase product is placed in an oven at 105±5℃ and dried for 8 h to obtain the hydrothermal solid phase product.

[0068] S4. The hydrothermal solid product is added to a glyphosate solution (100 mg / L) at a liquid-to-solid ratio of 100 mL / g. The pH is adjusted to 3 with concentrated nitric acid. The mixture is shaken at 25°C and 300 r / min for 2 h in a constant temperature shaker. The solid-liquid mixture is separated by centrifugation and filtered through a 0.45 μm filter membrane to obtain a solution sample.

[0069] Figure 4 The XRD analysis of the phase composition of the fly ash from waste incineration before treatment in Example 3 of the present invention, the XRD analysis of the phase composition of the sodalite-containing solid phase obtained by the hydrothermal reaction of waste incineration bottom ash in step S2, and the XRD analysis of the phase composition of the final hydrothermal solid phase product obtained after the low-temperature ultrasonic hydrothermal reaction in step S3 are as follows.

[0070] Soluble chlorine in the samples was determined using ion chromatography. Heavy metal leaching toxicity tests were conducted on the hydrothermal solid-phase products according to the standards "Solid Waste Leaching Toxicity Leaching Method: Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) and "Solid Waste Leaching Toxicity Leaching Method: Acetic Acid Buffer Solution Method" (HJ / T300-2007). The concentration of heavy metals in the leachate and hydrothermal waste liquid was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The dioxin content in the hydrothermal solid-phase products was analyzed using high-resolution gas chromatography / high-resolution mass spectrometry (HRGC / MS). Cation exchange capacity and heavy metal adsorption capacity tests were performed on the hydrothermal solid-phase products.

[0071] After treatment using the process described in this embodiment, the soluble chlorine in the fly ash was reduced to 36.48 mg / kg. The heavy metal leaching concentrations in the leachate, obtained using the "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid-Nitric Acid Method" (HJ / T 299-2007), were as follows: Zn: 0.189 mg / L, Pb: 0.125 mg / L, Cu: 0.326 mg / L, Cd: 0.015 mg / L, Cr: 0.017 mg / L, Ni: 0.016 mg / L. The leaching was performed using the "Solid Waste Leaching Toxicity Leaching Method - Acetic Acid Buffer Solution Method" (HJ / T300-2007). The heavy metal leaching concentrations in the leachate used in the heavy metal toxicity test were: Zn: 5.23 mg / L, Pb: 0.152 mg / L, Cu: 3.21 mg / L, Cd: 0.112 mg / L, Cr: 0.173 mg / L, Ni: 0.056 mg / L; the heavy metal concentrations in the hydrothermal waste liquid were: Zn: 0.458 mg / L, Pb: 0.162 mg / L, Cu: 0.135 mg / L. The concentrations of Cd, Cr, and Ni were 0.007 mg / L, 0.009 mg / L, and 0.004 mg / L, respectively. Therefore, after treatment with the process of this invention, the leaching concentrations of various heavy metals in the fly ash from municipal solid waste incineration are not only lower than the values ​​specified in the "Identification Standard for Hazardous Waste—Leaching Toxicity Identification" (GB5085.3-2007), but also meet the values ​​specified in the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2008). Furthermore, the content of various heavy metals in the hydrothermal waste liquid is extremely low, indicating that the heavy metals are effectively stabilized during the hydrothermal reaction and do not migrate to the hydrothermal waste liquid, thus preventing secondary pollution. The toxicity equivalent of dioxins is reduced to 1.28 TEQ μg / kg, a reduction of 95.10%. The solid product obtained after treatment with the process of this embodiment can reduce glyphosate from 100 mg / L to 1.23 mg / L within 120 minutes, demonstrating good adsorption performance.

[0072] The above results demonstrate that the present invention can efficiently and simultaneously remove soluble chlorine, stabilize heavy metals, and degrade and detoxify organic pollutants such as dioxins from waste incineration fly ash. This not only reduces disposal costs and improves disposal efficiency but also integrates the harmless disposal and high-value utilization of waste incineration fly ash. This makes the value creation of the present invention more suitable for my country's national conditions and provides a theoretical basis and technical support for the industrial development of harmless disposal and resource utilization of waste incineration fly ash.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0074] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for the segmented hydrothermal harmless treatment and high-value utilization of fly ash from waste incineration, characterized in that, The method for staged hydrothermal harmless treatment and high-value utilization of waste incineration fly ash includes the following steps: S1. Add fly ash to water for pre-washing treatment, and separate the washed fly ash and washing liquid. S2. Add the base ash and soluble aluminate to the washing solution, and after subcritical hydrothermal reaction, separate the sodalite-containing solid phase and the hydrothermal reaction solution. S3. Add the water-washed fly ash and oxidant to the hydrothermal reaction solution and carry out a low-temperature ultrasonic hydrothermal reaction. Then add the sodalite-containing solid phase and alkali and carry out a microwave hydrothermal reaction to separate and obtain the hydrothermal solid phase product. S4. Add the hydrothermal solid product to the polluted water body to remove pollutants; In step S2, the subcritical hydrothermal reaction is carried out at a temperature of 100-280℃ and for a time of 30-240 min. In step S2, the base ash and soluble aluminate are added to the washing solution to make the molar ratio of Si to Al 0.5-2.5:1; In step S3, the mass ratio of the water-washed fly ash to the sodalite-containing solid phase is 100:3-15.

2. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S1, the liquid-to-solid ratio of the water and fly ash is 5-50 mL / g.

3. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S1, the water washing pretreatment is carried out at a temperature of 20-50℃, for a time of 10-180 min, and with a oscillation speed of 100-1000 r / min.

4. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S3, the reaction temperature of the low-temperature ultrasonic hydrothermal reaction is 50-150℃, the reaction time is 10-240 min, the stirring speed is 200-500 r / min, and the ultrasonic frequency is 20-30 kHz.

5. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S3, the reaction temperature of the microwave hydrothermal reaction is 100-220℃, and the reaction time is 10-240 min.

6. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S3, the oxidant is selected from one or more of hydrogen peroxide and sodium percarbonate.

7. The method for segmented hydrothermal harmless treatment and high-value utilization of waste incineration fly ash according to claim 1, characterized in that, In step S4, the pH of the polluted water is 2-10.

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