Method for detoxification of waste incineration fly ash and enhancement of iron powder activity

Abstract

The present application provides a kind of method for detoxification of waste incineration fly ash and improving the activity of iron powder, belongs to the harmless disposal technical field of hazardous waste.The method comprises: evenly mixing waste incineration fly ash, clay powder and iron powder to obtain ash clay iron powder; evenly mixing water into the ash clay iron powder to obtain ash clay iron powder mud; evenly mixing oil sludge into the ash clay iron powder mud, granulating to obtain oil ash iron powder ceramsite raw material; drying the oil ash iron powder ceramsite raw material to obtain dried iron powder material; calcining the dried iron powder material to obtain calcined iron powder material; grinding and sorting the calcined iron powder material to obtain active iron powder and waste incineration fly ash detoxification powder.The preparation process of the present application is simple, and through high-temperature co-disposal of oil sludge, waste incineration fly ash and iron powder, efficient detoxification of waste incineration fly ash and simultaneous improvement of iron powder adsorption activity are realized.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste harmless disposal technology, specifically involving a method for detoxifying and enhancing the activity of iron powder using fly ash from waste incineration. Background Technology

[0002] Incineration enables rapid waste treatment and waste reduction, while also utilizing the heat from incineration for power generation and waste heat recovery. However, the incineration process generates a large amount of flue gas, which is treated and then collected as fly ash through bag filters. The production of fly ash from waste incineration is generally 3% to 5% of the incinerated waste. Currently, there are 678 waste-to-energy plants nationwide, producing nearly 12 million tons of fly ash annually. Fly ash contains approximately 1% heavy metal pollutants and highly toxic dioxins. Therefore, fly ash from waste incineration is significantly toxic to humans and is classified as hazardous waste, listed in the "National Hazardous Waste List," and managed accordingly.

[0003] Technical Specifications for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial)

[0004] HJ1134-2020 standardizes and guides the disposal and environmental management of fly ash from municipal solid waste incineration, setting clear limits for heavy metal leaching toxicity, dioxin content, and chlorine content in the disposal products of fly ash. Therefore, when harmlessly disposing of fly ash from municipal solid waste incineration, it is necessary to comprehensively consider the impact of various disposal factors on the heavy metal leaching toxicity, dioxin content, and chlorine content in the fly ash.

[0005] Currently, the main treatment methods for fly ash from waste incineration include landfilling, high-temperature melting, high-temperature sintering, and co-processing in cement kilns. However, these methods all have requirements regarding the chlorine content of the fly ash. Therefore, dechlorination pretreatment of the fly ash is necessary to meet these requirements, which is a cumbersome and demanding process. Moreover, the content of toxic substances remains high after treatment, resulting in poor treatment effectiveness. Additionally, co-processing of zinc-containing sludge with waste incineration fly ash is also currently being explored. While this method can reduce chlorine content, it requires a multi-stage water washing system for dechlorination, making the process complex. Furthermore, the resulting reduced iron powder has low activity and a small heavy metal adsorption capacity, leading to poor treatment results for heavy metal-contaminated water bodies. Summary of the Invention

[0006] The present invention aims to at least solve one of the above-mentioned technical problems existing in the prior art, and provides a method for detoxifying and enhancing the activity of iron powder using waste incineration fly ash, so as to achieve not only detoxification of waste incineration fly ash, but also enhancement of iron powder activity during the disposal of waste incineration fly ash.

[0007] This invention provides a method for detoxifying and enhancing the activity of iron powder using waste incineration fly ash, comprising: mixing waste incineration fly ash, clay powder, and iron powder evenly to obtain ash-adhesive iron powder;

[0008] Add water to the gray-bonded iron powder and mix evenly to obtain gray-bonded iron powder slurry;

[0009] Oily clay is added to the gray-bonded iron powder slurry and mixed evenly, then granulated to obtain oily-bonded iron powder ceramsite raw material;

[0010] The oil-based iron powder ceramsite raw meal is dried to obtain dried iron powder.

[0011] The dried iron powder is calcined to obtain calcined iron powder;

[0012] The calcined iron powder is ground and sorted to obtain active iron powder and waste incineration fly ash detoxification powder.

[0013] Optionally, the mass ratio of the waste incineration fly ash, the clay powder, and the iron powder is in the range of (2.5–22.5):(15–45):100.

[0014] Optionally, the liquid-to-solid ratio of the water to the gray-bonded iron powder is 25-45:100mL / g.

[0015] Optionally, the mass ratio of the oil sludge to the gray-bonded iron powder sludge is (0.5-4.5):100.

[0016] Optionally, the drying temperature range is 50℃ to 250℃, and the drying time ranges from 6 hours to 36 hours.

[0017] Optionally, the calcination time ranges from 20 minutes to 60 minutes, and the calcination temperature ranges from 700℃ to 1300℃.

[0018] Optionally, the grinding and sorting of the calcined iron powder to obtain activated iron powder and waste incineration fly ash detoxification powder includes:

[0019] The calcined iron powder is ground into powder, and the powder is magnetically separated. The magnetically separated powder is active iron powder, and the remaining powder is detoxification powder of waste incineration fly ash.

[0020] Optionally, the adsorption capacity of Cr(VI) in the active iron powder is higher than 68 mg / g, and the adsorption capacity of Hg(II) is higher than 32 mg / g.

[0021] Optionally, the Pb(II) leaching toxicity in the waste incineration fly ash detoxification powder is less than 8.5 × 10⁻⁶. -3 mg / L, Cd(II) leaching toxicity is less than 7.15 × 10 mg / L. -3mg / L, chlorine content less than 0.6%, and dioxin content less than 24 ng-TEQ / kg.

[0022] This invention proposes a method for detoxifying and enhancing the activity of iron powder using waste incineration fly ash, comprising: uniformly mixing waste incineration fly ash, clay powder, and iron powder to obtain ash-bonded iron powder; adding water to the ash-bonded iron powder and mixing uniformly to obtain ash-bonded iron powder sludge; adding oily sludge to the ash-bonded iron powder sludge and mixing uniformly, then granulating to obtain oily ash iron powder ceramsite raw material; drying the oily ash iron powder ceramsite raw material to obtain dried iron powder; calcining the dried iron powder to obtain calcined iron powder; and grinding and sorting the calcined iron powder to obtain active iron powder and waste incineration fly ash detoxification powder. The preparation process of this invention is simple, and through high-temperature synergistic treatment of oily sludge, waste incineration fly ash, and iron powder, it achieves efficient detoxification of waste incineration fly ash and simultaneously enhances the adsorption activity of iron powder. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a method for detoxifying and enhancing the activity of iron powder using fly ash from waste incineration, according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic flowchart of a method for detoxifying and enhancing the activity of iron powder using fly ash from waste incineration, according to an embodiment of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0026] Unless otherwise specifically stated, the technical or scientific terms used in this invention should be understood in their ordinary sense by one of ordinary skill in the art to which this invention pertains. The terms "comprising" or "including," as used in this invention, do not limit the numbers, steps, operations, and / or groups thereof mentioned, nor do they exclude the appearance or inclusion of one or more other different numbers, steps, operations, and / or groups thereof.

[0027] like Figure 1 and Figure 2 As shown, this invention proposes a method S100 for detoxifying and enhancing the activity of iron powder using fly ash from waste incineration, comprising steps S110 to S160:

[0028] S110. Mix the fly ash from waste incineration, clay powder, and iron powder evenly to obtain ash-clay-iron powder.

[0029] Specifically, in step S110, the powder is mixed according to the mass ratio of (2.5~22.5):(15~45):100 and stirred evenly to obtain gray sticky iron powder.

[0030] In this embodiment, when the waste incineration fly ash, clay powder, and iron powder are within the above-mentioned preferred mass ratio range, the prepared waste incineration fly ash detoxification powder has a low content of toxic substances, that is, the lowest toxicity, and the active iron powder has a high heavy metal adsorption content.

[0031] It should be noted that when the concentration is below the above-mentioned preferred range, the amount of waste incineration fly ash and clay powder added is relatively small, and the catalytic cracking, carbothermic chlorination, and carbon-iron reaction are all insufficient. As a result, the toxicity of the waste incineration fly ash detoxification powder increases significantly as the mass ratio of waste incineration fly ash, clay powder, and iron powder decreases, while the adsorption capacity of active iron powder decreases significantly as the mass ratio of waste incineration fly ash, clay powder, and iron powder decreases.

[0032] It should be further noted that when the amount of fly ash and clay powder added exceeds the above-mentioned preferred range, the reaction between materials becomes unbalanced. This leads to a significant increase in the toxicity of the fly ash detoxification powder as the mass ratio of fly ash, clay powder, and iron powder increases further, while the adsorption capacity of the active iron powder decreases significantly as the mass ratio of fly ash, clay powder, and iron powder increases further.

[0033] S120. Add water to the gray-sticky iron powder and mix evenly to obtain gray-sticky iron powder mud.

[0034] Specifically, water is added to the gray-bonded iron powder at a liquid-to-solid ratio of 25–45:100 mL / g, and the mixture is stirred evenly to obtain gray-bonded iron powder slurry.

[0035] S130. Add oil mud to gray-bonded iron powder mud, mix evenly, granulate, and obtain oil-bonded iron powder ceramsite raw material.

[0036] Specifically, oily clay is added to gray-bonded iron powder mud at a mass ratio of (0.5 to 4.5): 100, stirred evenly, and granulated to obtain oily gray iron powder ceramsite raw material.

[0037] In this embodiment, when the oil sludge and the ash-adhesive iron powder sludge are within the above-mentioned preferred mass ratio range, the prepared waste incineration fly ash detoxification powder has a low content of toxic substances, that is, the lowest toxicity, and the active iron powder has a high heavy metal adsorption content.

[0038] It should be noted that when the content is below the above-mentioned preferred range, the amount of oil sludge added is small, and the reaction between materials is insufficient. This results in a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the mass ratio of oil sludge to ash-adhesive iron powder decreases, while the adsorption capacity of the active iron powder decreases significantly as the mass ratio of oil sludge to ash-adhesive iron powder decreases.

[0039] It should be further noted that when the amount of oil sludge added exceeds the above-mentioned preferred range, the reaction between materials becomes unbalanced, resulting in a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the mass ratio of oil sludge to ash-adhered iron powder sludge further increases, while the adsorption capacity of activated iron powder significantly decreases as the mass ratio of oil sludge to ash-adhered iron powder sludge further increases.

[0040] S140. Dry the raw iron powder ceramsite meal to obtain dried iron powder.

[0041] Specifically, the raw material of oil-based iron powder ceramsite is dried for 6 to 36 hours to obtain dried iron powder, wherein the drying temperature is 50 to 250℃.

[0042] S150. The dried iron powder is calcined to obtain calcined iron powder.

[0043] Specifically, the dried iron powder is loaded into a kiln for calcination for 20 to 60 minutes, then poured out and cooled to obtain calcined iron powder, wherein the calcination temperature is 700 to 1300℃.

[0044] In this embodiment, when the calcination time is within the above-mentioned preferred range, the prepared waste incineration fly ash detoxification powder has a low content of toxic substances, that is, the lowest toxicity, and the active iron powder has a high content of heavy metal adsorption.

[0045] It should be noted that when the calcination time is less than the above-mentioned preferred range, the calcination time is insufficient and the reaction is incomplete. This leads to a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the calcination time decreases, while the adsorption capacity of the active iron powder decreases significantly as the calcination time decreases.

[0046] It should be further noted that when the calcination time is longer than the above-mentioned preferred range, the calcination time is too long and the material is over-calcined, which causes the toxicity of the waste incineration fly ash detoxification powder to increase significantly with the further increase of calcination time, while the adsorption capacity of the active iron powder decreases significantly with the further increase of the mass ratio of oil sludge and ash-adhesive iron powder sludge.

[0047] S160. Grind and sort the calcined iron powder to obtain active iron powder and waste incineration fly ash detoxification powder.

[0048] Specifically, calcined iron powder is ground into powder, and the iron powder is separated by magnetic separation. The resulting iron powder is active iron powder, and the remaining powder after separating the iron powder is waste incineration fly ash detoxification powder.

[0049] It should be noted that, in this embodiment, the reaction mechanism is as follows: During the calcination of dried iron powder, inorganic chlorides in the waste incineration fly ash catalyze the mineralization and decomposition of dioxin pollutants under high temperature conditions, and catalyze the decomposition of organic matter in the sludge to generate carbon dioxide, water vapor, and small molecule organic gases. Simultaneously, inorganic chlorides and water vapor in the waste incineration fly ash permeate and migrate into the iron powder particles, destroying the metallographic structure of the iron powder through potentiometric corrosion and chemical corrosion, increasing the binding energy and adsorption activity of the iron powder. The small molecule organic gases generated by the sludge decomposition can inhibit electron loss from the iron powder metallographic structure through surface reduction, preventing the iron powder from losing its activity due to excessive corrosion and oxidation. Furthermore, the water vapor and small molecule organic gases released by the sludge decomposition can also increase the mineral activity in the clay powder, thereby promoting the reaction between the clay powder and the waste incineration fly ash. The iron oxides oxidized from some of the iron powder and the chlorides in the waste incineration fly ash can act as a solvent and adhesive initiator, accelerating the melting of the clay powder, thereby further promoting the reaction and fusion of the molten clay powder with the mineral components in the waste incineration fly ash, forming a stable sintered body. Heavy metal pollutants in waste incineration fly ash are effectively fixed in the clay powder melt. Calcined iron powder is ground into powder, and the magnetic iron powder is separated out. The remaining solid powder is the detoxified sintered waste incineration fly ash.

[0050] Furthermore, based on the method provided in this embodiment, the activated iron powder prepared has a Cr(VI) adsorption capacity higher than 68 mg / g and a Hg(II) adsorption capacity higher than 32 mg / g. The Pb(II) leaching toxicity in the waste incineration fly ash detoxification powder is lower than 8.5 × 10⁻⁶ mg / g. -3 mg / L, Cd(II) leaching toxicity is less than 7.15 × 10 mg / L. -3 The concentration of iron powder is mg / L, the chlorine content is less than 0.6%, and the dioxin content is less than 24 ng-TEQ / kg. In other words, the method of this invention can detoxify fly ash from waste incineration while simultaneously enhancing the activity of iron powder.

[0051] The following will further illustrate the method of detoxifying and enhancing the activity of iron powder using fly ash from waste incineration, with several specific examples:

[0052] Example 1

[0053] This example illustrates the effect of different mass ratios of waste incineration fly ash, clay powder, and iron powder on the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder, including the following steps:

[0054] S1. According to the mass ratios 1:15:100, 1.5:15:100, 2:15:100, 2.5:7.5:100, 2.5:10:100, 2.5:12.5:100, 2.5:15:100, 12.5:15:100, 22.5:15:100, 2.5:30:100, 12.5:30:100, 22.5:3 Mix 0:100, 2.5:45:100, 12.5:45:100, 22.5:45:100, 22.5:50:100, 22.5:55:100, 22.5:60:100, 25:45:100, 27.5:45:100, and 30:45:100 respectively with waste incineration fly ash, clay powder, and iron powder, and stir evenly to obtain ash-clay-iron powder;

[0055] S2. Add water to the gray-bonded iron powder according to the liquid-solid ratio of 25:100mL / g, stir evenly, and obtain gray-bonded iron powder mud.

[0056] S3. Add oil mud to the gray-bonded iron powder mud at a mass ratio of 0.5:100, stir evenly, granulate, and obtain oil-bonded iron powder ceramsite raw material.

[0057] S4. Dry the oil-based iron powder ceramsite raw material for 6 hours to obtain dried iron powder material, wherein the drying temperature is 50℃;

[0058] S5. The dried iron powder is loaded into the kiln for calcination for 20 minutes. It is then poured out and cooled to obtain calcined iron powder, wherein the calcination temperature is 700℃.

[0059] S6. Grind the calcined iron powder into powder, separate the iron powder by magnetic separation, and obtain active iron powder. The remaining powder after separating the iron powder is the detoxification powder of waste incineration fly ash.

[0060] It should be noted that the waste incineration fly ash red mud used in this embodiment was provided by a waste incineration power plant company in Changshu, Jiangsu Province. The main components detected include: 36.2% CaO, 23.9% Cl, 11.0% SO3, 11.6% Na2O, 6.33% K2O, 4.38% SiO2, 1.40% Fe2O3, 1.25% Al2O3 and other components.

[0061] It should be further noted that this embodiment also tested the heavy metal content, chlorine content, and dioxin content of the prepared waste incineration fly ash detoxification powder, and treated and measured the water containing heavy metal ions. Please refer to the following text for the specific measurement process, and the measurement results are shown in Table 1.

[0062] Among them, the heavy metal leaching test of the fly ash detoxification powder from waste incineration was conducted: the fly ash detoxification powder from waste incineration was used to prepare leachate according to the method of "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The concentration of heavy metals in the leachate was measured using inductively coupled plasma mass spectrometry (Inductively Coupled Plasma Mass Spectrometry) by Thermo Scientific. TM ELEMENT TM ) to conduct testing.

[0063] Determination of chlorine content in waste incineration fly ash detoxification powder: The chlorine content in waste incineration fly ash detoxification powder was determined in accordance with the "Building Sand" standard (GB / T 14684-2011).

[0064] Test for dioxin content in fly ash detoxification powder from waste incineration: The test for dioxin content in fly ash detoxification powder from waste incineration shall be carried out in accordance with the Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (HJ1134).

[0065] Treatment of water containing heavy metal ions: The iron-based adsorbent powder was added to water containing 200 mg / L Cr(VI) and 50 mg / L Hg(II) at an initial pH of 2 and with a solid / liquid ratio of 1 g: 1 L. The mixture was stirred at 120 rpm for 10 min.

[0066] The concentrations of heavy metal ions in the water were determined. The concentrations of Pb(II) and Cd(II) pollutants were determined according to the "Determination of 32 Elements in Water by Inductively Coupled Plasma Atomic Emission Spectrometry" (HJ 776-2015), the concentration of Cr(VI) pollutant was determined according to the "Determination of Hexavalent Chromium in Water by Flow Injection-Diphenylcarbazide Spectrophotometry" (HJ 908-2017), and the concentration of Hg(II) pollutant was determined according to the "Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony in Water by Atomic Fluorescence Spectrometry" (HJ 694-2014).

[0067] Table 1. Effects of different mass ratios of waste incineration fly ash, clay powder, and iron powder on the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder.

[0068]

[0069]

[0070] As shown in Table 1 above, when the mass ratio of waste incineration fly ash, clay powder, and iron powder is less than 2.5:15:100 (for example, the mass ratio of waste incineration fly ash, clay powder, and iron powder = 1.5:20:100, 1:20:100, 0.5:20:100, 2:17.5:100, 2:15:100, 2:12.5:100, and even lower ratios not listed in Table 1), the addition of waste incineration fly ash and clay powder is insufficient, resulting in incomplete catalytic cracking, carbothermic chlorination, and carbon-iron reaction. Consequently, the toxicity of waste incineration fly ash detoxification powder increases significantly as the mass ratio of waste incineration fly ash, clay powder, and iron powder decreases, while the adsorption capacity of active iron powder decreases significantly as the mass ratio of waste incineration fly ash, clay powder, and iron powder decreases.

[0071] Furthermore, when the mass ratio of waste incineration fly ash, clay powder, and iron powder is equal to 2.5–22.5:15–45:100 (for example, the mass ratios of waste incineration fly ash, clay powder, and iron powder are 2.5:15:100, 12.5:15:100, 22.5:15:100, 2.5:30:100, 12.5:30:100, 22.5:30:100, 2.5:45:100, 12.5:45:100, and 22.5:45:100), the dried iron powder is calcined. During the process, under high-temperature conditions, inorganic chloride salts in the fly ash from waste incineration catalyze the mineralization and decomposition of dioxin pollutants, and catalyze the decomposition of organic matter in oil sludge to generate carbon dioxide, water vapor, and small molecule organic gases. At the same time, inorganic chloride salts and water vapor in the fly ash from waste incineration permeate and migrate into iron powder particles, destroying the metallographic structure of iron powder through potential corrosion and chemical corrosion, increasing the binding energy and adsorption activity of iron powder. Meanwhile, the small molecule organic gases generated by the decomposition of oil sludge can inhibit the loss of electrons in the metallographic structure of iron powder through surface reduction, preventing iron powder from losing its activity due to excessive corrosion and oxidation.

[0072] Ultimately, the Pb(II) leaching toxicity of the waste incineration fly ash detoxification powder prepared within the above-mentioned preferred mass ratio range was all below 8.5 × 10⁻⁶. -3 The Cd(II) leaching toxicity was below 7.15 × 10 mg / L. -3 mg / L, chlorine content was less than 0.6%, dioxin content was less than 24 ng-TEQ / kg; the adsorption capacity of Cr(VI) of active iron powder was greater than 68 mg / g, and the adsorption capacity of Hg(II) was greater than 32 mg / g.

[0073] Furthermore, when the mass ratio of waste incineration fly ash, clay powder, and iron powder is greater than 22.5:45:100 (e.g., mass ratios of waste incineration fly ash, clay powder, and iron powder = 22.5:50:100, 22.5:55:100, 22.5:60:100, 25:45:100, 27.5:45:100, 30:45:100, and higher ratios not listed in Table 1), the excessive addition of waste incineration fly ash and clay powder leads to an imbalance in the reaction between materials. This results in a significant increase in the toxicity of waste incineration fly ash detoxification powder as the mass ratio of waste incineration fly ash, clay powder, and iron powder further increases, while the adsorption capacity of activated iron powder significantly decreases as the mass ratio of waste incineration fly ash, clay powder, and iron powder further increases.

[0074] Therefore, overall, considering both benefits and costs, in this embodiment, the optimal ratio of the mass of waste incineration fly ash, clay powder, and iron powder to 2.5–22.5:15–45:100 is most conducive to improving the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder.

[0075] Example 2

[0076] This example illustrates the effect of different mass ratios of oily sludge and ash-adhered iron powder sludge on the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder, including the following steps:

[0077] S1. Mix the waste incineration fly ash, clay powder, and iron powder in a mass ratio of 22.5:45:100, stir evenly, and obtain ash-clay-iron powder.

[0078] S2. Add water to the gray-bonded iron powder according to the liquid-solid ratio of 35:100mL / g, stir evenly, and obtain gray-bonded iron powder mud.

[0079] S3. Add oil mud to the gray-bonded iron powder mud according to the mass ratio of 0.25:100, 0.3:100, 0.4:100, 0.5:100, 2.5:100, 4.5:100, 5:100, 5.5:100, and 6:100, stir evenly, granulate, and obtain oil-bonded iron powder ceramsite raw material;

[0080] S4. Dry the oil-based iron powder ceramsite raw material for 21 hours to obtain dried iron powder material, wherein the drying temperature is 150℃.

[0081] S5. The dried iron powder is loaded into the kiln for calcination for 40 minutes. It is then poured out and cooled to obtain calcined iron powder, wherein the calcination temperature is 1000℃.

[0082] S6. Grind the calcined iron powder into powder, separate the iron powder by magnetic separation, and obtain active iron powder. The remaining powder after separating the iron powder is the detoxification powder of waste incineration fly ash.

[0083] It should be noted that the heavy metal leaching test, chlorine content determination, dioxin content detection test in the waste incineration fly ash and waste incineration fly ash detoxification powder, and the treatment and determination process of water containing heavy metal ions used in this embodiment are all the same as in Example 1, and the determination results are shown in Table 2.

[0084] Table 2. Effects of different mass ratios of oily sludge and ash-adhered iron powder on the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder.

[0085]

[0086] As shown in Table 2 above, when the mass ratio of oily sludge to ash-bonded iron powder sludge is less than 0.5:100 (for example, the mass ratio of oily sludge to ash-bonded iron powder sludge = 0.4:100, 0.3:100, 0.25:100 and lower ratios not listed in Table 2), less oily sludge is added, and the reaction between materials is insufficient. This leads to a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the mass ratio of oily sludge to ash-bonded iron powder sludge decreases, while the adsorption capacity of activated iron powder decreases significantly as the mass ratio of oily sludge to ash-bonded iron powder sludge decreases.

[0087] Furthermore, when the mass ratio of oily sludge to ash-bonded iron powder is 0.5–4.5:100 (e.g., oily sludge to ash-bonded iron powder mass ratio = 0.5:100, 2.5:100, 4.5:100), during the drying and calcination of the iron powder, the inorganic chloride salts in the waste incineration fly ash catalyze the mineralization and decomposition of dioxin pollutants under high temperature conditions, and catalyze the decomposition of organic matter in the oily sludge to generate carbon dioxide, water vapor, and small molecule organic gases. Simultaneously, the inorganic chloride salts and water vapor in the waste incineration fly ash permeate and migrate into the iron powder particles, destroying the metallographic structure of the iron powder through potentiometric corrosion and chemical corrosion, increasing the binding energy and adsorption activity of the iron powder. The small molecule organic gases generated by the decomposition of the oily sludge can inhibit the loss of electrons in the metallographic structure of the iron powder through surface reduction, preventing the iron powder from losing its activity due to excessive corrosion and oxidation. At the same time, the water vapor and small molecule organic gases released by the decomposition of the oily sludge can also increase the mineral activity in the clay powder, thereby promoting the reaction between the clay powder and the waste incineration fly ash. Iron oxides formed by the partial oxidation of iron powder and chloride salts in waste incineration fly ash can act as solvents and adhesive initiators, accelerating the melting of clay powder. This further promotes the reaction and fusion of the molten clay powder with the mineral components in the waste incineration fly ash, forming a stable sintered body.

[0088] Ultimately, the Pb(II) leaching toxicity of the waste incineration fly ash detoxification powder prepared within the above-mentioned preferred mass ratio range was all below 2.8 × 10⁻⁶. -4 The Cd(II) leaching toxicity was below 5.4 × 10 mg / L. -5mg / L, chlorine content was less than 0.5%, dioxin content was less than 17 ng-TEQ / kg; the adsorption capacity of Cr(VI) of active iron powder was greater than 77 mg / g, and the adsorption capacity of Hg(II) was greater than 39 mg / g.

[0089] Furthermore, when the mass ratio of oily sludge to ash-adhered iron powder sludge is greater than 4.5:100 (e.g., oily sludge to ash-adhered iron powder sludge mass ratio = 5:100, 5.5:100, 6:100 and higher ratios not listed in Table 2), the excessive addition of oily sludge leads to an imbalance in the reaction between materials. This results in a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the mass ratio of oily sludge to ash-adhered iron powder sludge further increases, while the adsorption capacity of activated iron powder significantly decreases as the mass ratio of oily sludge to ash-adhered iron powder sludge further increases.

[0090] Therefore, overall, considering both benefits and costs, in this embodiment, the ratio of oily sludge to ash-adhesive iron powder sludge of 0.5 to 4.5:100 is most conducive to improving the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder.

[0091] Example 3

[0092] This example illustrates the effect of different calcination times on the performance of the prepared waste incineration fly ash detoxification powder and activated iron powder, including the following steps:

[0093] S1. Mix the waste incineration fly ash, clay powder, and iron powder in a mass ratio of 22.5:45:100, stir evenly, and obtain ash-clay-iron powder.

[0094] S2. Add water to the gray-bonded iron powder according to the liquid-solid ratio of 45:100mL / g, stir evenly, and obtain gray-bonded iron powder mud.

[0095] S3. Add oil mud to the gray-bonded iron powder mud at a mass ratio of 4.5:100, stir evenly, granulate, and obtain oil-bonded iron powder ceramsite raw material.

[0096] S4. Dry the raw iron powder ceramsite meal for 36 hours to obtain dried iron powder, wherein the drying temperature is 250℃.

[0097] S5. The dried iron powder is loaded into the kiln for calcination for 5 minutes, 10 minutes, 15 minutes, 20 minutes, 40 minutes, 60 minutes, 65 minutes, 70 minutes and 75 minutes. The powder is then poured out and cooled to obtain calcined iron powder, wherein the calcination temperature is 1300℃.

[0098] S6. Grind the calcined iron powder into powder, separate the iron powder by magnetic separation, and obtain active iron powder. The remaining powder after separating the iron powder is the detoxification powder of waste incineration fly ash.

[0099] It should be noted that the heavy metal leaching test, chlorine content determination, dioxin content detection test in the waste incineration fly ash and waste incineration fly ash detoxification powder, and the treatment and determination of water containing heavy metal ions used in this embodiment are all the same as in Example 1, and the test results are shown in Table 3.

[0100] Table 3. Effects of different calcination times on the properties of the prepared waste incineration fly ash detoxification powder and active iron powder.

[0101]

[0102] As shown in Table 3 above, when the calcination time is less than 20 minutes (for example, calcination time = 15 minutes, 10 minutes, 5 minutes and lower ratios not listed in Table 3), the calcination time is insufficient and the reaction is incomplete. This leads to a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the calcination time decreases, while the adsorption capacity of the active iron powder decreases significantly as the calcination time decreases.

[0103] Furthermore, when the calcination time is between 20 and 60 minutes (e.g., calcination time = 20 minutes, 40 minutes, 60 minutes), during the calcination of dried iron powder, the inorganic chloride salts in the waste incineration fly ash catalyze the mineralization and decomposition of dioxin pollutants under high-temperature conditions, and catalyze the decomposition of organic matter in the oil sludge to generate carbon dioxide, water vapor, and small molecule organic gases. Simultaneously, the inorganic chloride salts and water vapor in the waste incineration fly ash permeate and migrate into the iron powder particles, destroying the metallographic structure of the iron powder through potentiometric corrosion and chemical corrosion, increasing the binding energy and adsorption activity of the iron powder. The small molecule organic gases generated by the decomposition of the oil sludge can inhibit the loss of electrons in the metallographic structure of the iron powder through surface reduction, preventing the iron powder from losing its activity due to excessive corrosion and oxidation. At the same time, the water vapor and small molecule organic gases released by the decomposition of the oil sludge can also increase the mineral activity in the clay powder, thereby promoting the reaction between the clay powder and the waste incineration fly ash. Iron oxides from partial iron powder oxidation and chloride salts from waste incineration fly ash act as solvents and adhesive initiators, accelerating the melting of clay powder. This further promotes the reaction and fusion of the molten clay powder with the mineral components in the waste incineration fly ash, forming a stable sintered body. Heavy metal pollutants in the waste incineration fly ash are effectively fixed within the molten clay powder.

[0104] Ultimately, the Pb(II) leaching toxicity of the prepared waste incineration fly ash detoxification powder was all below 6.9 × 10⁻⁶. -5 The Cd(II) leaching toxicity was below 7.2 × 10 mg / L. -6 mg / L, chlorine content was less than 0.4%, dioxin content was less than 13 ng-TEQ / kg; the adsorption capacity of Cr(VI) of active iron powder was greater than 84 mg / g, and the adsorption capacity of Hg(II) was greater than 44 mg / g.

[0105] Furthermore, when the calcination time is greater than 60 minutes (e.g., calcination time = 65 minutes, 70 minutes, 75 minutes and higher ratios not listed in Table 3), the calcination time is too long and the material is over-calcined, which leads to a significant increase in the toxicity of the waste incineration fly ash detoxification powder as the calcination time increases further, while the adsorption capacity of the active iron powder decreases significantly as the mass ratio of oil sludge and ash-adhesive iron powder sludge increases further.

[0106] Therefore, overall, considering both benefits and costs, in this embodiment, a calcination time of 20 to 60 minutes is most conducive to improving the performance of the prepared waste incineration fly ash detoxification powder and active iron powder.

[0107] This invention proposes a method for detoxifying and enhancing the activity of iron powder using fly ash from waste incineration, which has the following beneficial effects:

[0108] First, the preparation process of this invention is simple. By using high temperature to synergistically treat oil sludge, waste incineration fly ash, and iron powder, it achieves efficient detoxification of waste incineration fly ash and simultaneously enhances the adsorption activity of iron powder. Compared with the original iron powder, the adsorption capacity of the treated iron powder is significantly increased.

[0109] Second, the chlorine content of the waste incineration fly ash after detoxification using the method of this invention is less than 1%, and the heavy metal leaching concentration and dioxin content both meet the pollution control requirements of the "Technical Specification for Pollution Control of Municipal Solid Waste Incineration Fly Ash" (HJ1134-2020).

[0110] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for detoxification and activity enhancement of iron powder using waste incineration fly ash, characterized by, The application relates to a method for preparing active iron powder and waste incineration fly ash detoxification powder. The waste incineration fly ash, clay powder and iron powder are mixed uniformly to obtain ash-clay-iron powder; the mass ratio of the waste incineration fly ash, the clay powder and the iron powder ranges from 2.5 to 22.5, from 15 to 45 and 100 respectively; Water is added into the ash-clay-iron powder to mix uniformly to obtain ash-clay-iron powder mud; Oil mud is added into the ash-clay-iron powder mud to mix uniformly, granulation is carried out to obtain oil ash-iron powder ceramsite raw material; the mass ratio of the oil mud and the ash-clay-iron powder mud ranges from 0.5 to 4.5 to 100; The oil ash-iron powder ceramsite raw material is dried to obtain dried iron powder material; The dried iron powder material is calcined for 20 to 60 minutes to obtain calcined iron powder material; The calcined iron powder material is ground and sorted to obtain active iron powder and waste incineration fly ash detoxification powder. The Cr(VI) adsorption capacity of the active iron powder is higher than 68 mg / g, and the Hg(II) adsorption capacity is higher than 32 mg / g.

2. The method of claim 1, wherein, The liquid-solid ratio of the water and the ash-clay-iron powder ranges from 25 to 45 to 100 mL / g.

3. The method of claim 1, wherein, The drying temperature ranges from 50 DEG C to 250 DEG C, and the drying time ranges from 6 to 36 hours.

4. The method of claim 1, wherein, The calcination temperature ranges from 700 DEG C to 1300 DEG C.

5. The method according to any one of claims 1 to 4, characterized in that, The calcined iron powder material is ground and sorted to obtain active iron powder and waste incineration fly ash detoxification powder, which comprises the following steps: The calcined iron powder material is ground into powder, and the powder is subjected to magnetic separation; the powder separated by the magnetic separation is active iron powder, and the remaining powder is waste incineration fly ash detoxification powder.

6. The method according to any one of claims 1 to 4, characterized in that, The Pb(II) leaching toxicity of the waste incineration fly ash detoxification powder is lower than 8.5 x 10 -3 mg / L, the Cd(II) leaching toxicity is lower than 7.15 x 10 -3 mg / L, the chlorine content is lower than 0.6%, and the dioxin content is lower than 24 ng-TEQ / kg.

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