Method for improving activity of detoxification fly ash and application of detoxification fly ash

Abstract

The invention discloses a method for improving the activity of detoxified fly ash. The detoxified fly ash is obtained by performing low-temperature thermal decomposition pretreatment, three-stage water washing, plate-frame pressure filtration separation, crushing and sieving on waste incineration fly ash; fully and uniformly mixing the detoxified fly ash and the composite exciting agent in proportion, and pre-grinding until the specific surface area is 400-500 m < 2 > / kg; carrying out damp-heat curing on the ground product; adding a microwave synergist into the cured detoxified fly ash-based active powder, and performing synergistic activation under microwave-assisted heating; and adding an organic silicon water repellent into the powder for surface modification, carrying out auxiliary grinding with triethanolamine, and carrying out ultrafine grinding on the activated material until the specific surface area is 600-800 m < 2 > / kg, so as to obtain the detoxification fly ash with improved activity. The activity of the detoxified fly ash is improved by adopting a stepped activation method of graded grinding, chemical excitation, damp and hot maintenance and microwave activation, the bottleneck of a single technology is broken through, and the dual goals of activity improvement and heavy metal stabilization are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and particularly relates to a method for enhancing the activity of detoxified fly ash and an application thereof. Background Art

[0002] Waste incineration fly ash is classified as hazardous waste because it contains dioxins and heavy metals. After washing and heat treatment for detoxification, it can be used as a raw material for building materials, but there are still problems such as low activity and insufficient utilization rate.

[0003] Existing technologies mostly use single chemical excitation (such as alkali excitation) or physical grinding, which still has the following defects: (1) The excitation efficiency is low, and a single exciter is difficult to destroy the stable glass structure in fly ash; (2) The activity improvement is limited and the mineral matching is not optimized, resulting in insufficient production of hydration products; (3) The cost is high. Some processes require high-temperature calcination to change the crystal phase composition, resulting in high energy consumption and cost.

[0004] Existing technologies use a single alkaline activator (sodium hydroxide) to enhance activity, but this suffers from low activation efficiency and prone to alkali reversion. Mechanical grinding combined with mineral modification fails to address the risk of secondary heavy metal release. Calcination activation is also used to enhance activity, but this results in high energy consumption and severe particle agglomeration. These methods generally suffer from limited activity enhancement, complex processes, and uncontrolled environmental risks. Summary of the Invention

[0005] In order to solve at least one of the above problems, the present invention provides a method for improving the activity of detoxified fly ash and its application.

[0006] In order to achieve the above object, the present invention adopts the following technical means: A first aspect of the present invention provides a method for increasing the activity of detoxified fly ash, comprising the following steps: S1. The waste incineration fly ash is subjected to low-temperature thermal decomposition pretreatment, three-stage water washing, and plate-and-frame filter press separation to obtain a detoxified fly ash product, and the detoxified fly ash product is crushed and sieved to obtain detoxified fly ash; S2. Detoxified fly ash and a composite activator are thoroughly mixed in a mass ratio of (70% to 85%): (15% to 30%) and then pre-ground to a specific surface area of ​​400 to 500 m² / kg; the composite activator is composed of mineral powder, fly ash, and gypsum; S3, the product after grinding in S2 is subjected to wet heat curing at 50-70°C and humidity ≥90% for 6 hours; S4, adding a microwave synergist to the detoxified fly ash-based active powder after curing, and activating it under microwave-assisted heating; the microwave synergist comprises silicon slag powder and ferrous oxide; S5. Cool the powder obtained in step S4, add 0.5% to 1.5% of an organosilicon hydrophobic agent for surface modification, and 0.1% to 0.5% of triethanolamine for auxiliary grinding. Ultrafinely grind the activated material to a specific surface area of ​​600 to 800 m² / kg to obtain detoxified fly ash with enhanced activity.

[0007] The ultrafine grinding adopts air flow grinding technology. High-speed air flow (300-500m / s) drives the particles to collide and crush. The built-in classifying wheel realizes dynamic particle size control and controls the particle size D50≤5μm.

[0008] In some embodiments of the present invention, in step S2, the mass ratio of mineral powder: fly ash: gypsum in the composite activator is (40%~60%): (30%~50%): (10%~20%). The slag powder in the composite activator must meet the national standard GB / T 18046-2017, Grade S95 commercially available slag. Its main technical indicators are: specific surface area (m2 / kg) ≥400, 7-day activity index ≥70%, 28-day activity index ≥95%, fluidity ratio ≥95%, initial setting time ratio ≤200%, sulfur trioxide (mass fraction) ≤4%, and chloride ion (mass fraction) ≤0.06%. The fly ash must be Grade II low-calcium ash and must meet the requirements of GB / T 1596-2017. Its main technical indicators are: water demand ratio ≤105%, SiO2+Al2O3 ≥70%, sulfur trioxide (mass fraction) ≤3%, and 28-day activity index ≥75%. The gypsum must be industrial by-product gypsum and must meet the requirements of GB / T 21371-2019. Its main technical indicators are: gypsum grade ≥75%, chloride ion (mass fraction) ≤0.5%, and moisture content ≤10%.

[0009] In some embodiments of the present invention, in step S4, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is (90-95%): (5-10%).

[0010] In some embodiments of the present invention, in step S4, the amount of the microwave synergist is 5-7% of the mass of the detoxified fly ash-based active powder.

[0011] In some embodiments of the present invention, in step S4, the microwave-assisted heating conditions are: microwave frequency 2.45 GHz, power density 3-5 W / g.

[0012] In some embodiments of the present invention, in step S1, the low-temperature thermal decomposition pretreatment method is: keeping the temperature at 350-400° C. for 60-90 minutes in the absence of oxygen to dechlorinate and detoxify dioxins in the fly ash.

[0013] In some embodiments of the present invention, in step S1, the detoxified fly ash product is separated by plate and frame filter press with a moisture content of 15-20%. The filter press equipment in this step is a new air-energy plate and frame filter press with a feed pressure of 6-10 kg / cm 2 , water pressing pressure 12-16 kg / cm 2 , air pressing pressure 4.5-10 kg / cm 2 , pressing time 10-15min.

[0014] In some embodiments of the present invention, in step S1, the detoxified fly ash product is crushed and sieved to pass through a 75 μm sieve with a sieve residue of no more than 15%. This step utilizes a vertical mill with multiple upper and lower blades and chain crushing, which effectively achieves the multiple effects of crushing, grinding, and granulation, and has a moisture tolerance of 25-50%.

[0015] The dioxin, heavy metal, and soluble chloride content of the detoxified fly ash treated in step S1 must meet the requirements of the "Technical Specification for Pollution Control of Municipal Waste Incineration Fly Ash" (HJ 1134-2020): the dioxin content of the detoxified fly ash product must not exceed 50 ng-TEQ / kg, the heavy metal concentration in the leachate prepared according to HJ 557 must not exceed the first-level implementation standard of the maximum allowable emission concentration for Category II pollutants in GB 8978, and the soluble chlorine content must not exceed 1%. It must also be identified as a solid waste according to GB 34330 and managed as general industrial solid waste.

[0016] The second aspect of the present invention provides detoxified fly ash with enhanced activity prepared according to the method described in the first aspect.

[0017] The third aspect of the present invention provides the application of the detoxified fly ash with enhanced activity described in the second aspect. The detoxified fly ash with enhanced activity is used as a composite admixture in the production of concrete, as an active admixture in the production of cement, as a low-carbon cementitious material to replace 30-50% of cement in the production of cement products, and as an inorganic binder for roadbed materials to stabilize gravel or solidify soil.

[0018] Beneficial effects of the present invention Compared with the prior art, the present invention has the following beneficial effects: The detoxified fly ash product has a low moisture content, which can ensure the effect of pre-crushed particle size on the one hand, and provide a small amount of reaction water for the next step of composite chemical excitation on the other hand; after the exciter is prepared and initially mixed, the surface defects of the powder particles can be increased after pre-grinding, which is beneficial to Ca 2+ Ion penetration and dissolution of silicon and aluminum in slag and fly ash, detoxification of large amounts of Ca in fly ash and gypsum 2+, can interact more actively with active anions such as silicate and aluminate in an alkaline environment to generate hydration products such as CSH, CAH gel and ettringite (AFt). The CaO-Al2O3-SiO2 glass in the mineral powder is in the alkaline environment provided by the detoxified fly ash and the SO4 provided by gypsum. 2- The depolymerization is carried out under low temperature to generate CSH gel and ettringite (AFt); the active SiO2 in fly ash reacts with the free CaO in the detoxified fly ash to generate secondary hydration products, forming a dense network structure and improving the activity of the detoxified fly ash product; aging and curing accelerates ion diffusion and promotes the formation of gel cross-linking network; microwaves are used to selectively heat polar substances such as Ca(OH)2 in fly ash. Microwave treatment can change the surface chemical state of the material, promote the desorption or rearrangement of surface hydroxyl groups (-OH), and expose more Ca 2+ Active sites; inhibit surface carbonization and reduce the probability of surface carbonation: CaO, Ca(OH)2→CaCO3. In addition, the Fe element in the microwave enhancer has a good wave absorption effect, high electromagnetic energy conversion efficiency, good projection, and can effectively bombard and destroy the silicon-oxygen tetrahedral structure inside and on the surface of the powder particles, significantly breaking the chemical bonds and maintaining a highly active surface. After ultrafine grinding, the surface energy of the particles increases, promoting ion migration and crystal nucleation. The small amount of heavy metals in the detoxified fly ash forms an isomorphous substitution structure with silicate minerals. The gelled mineral phase formed at the same time has a strong stabilizing binding effect on the heavy metals through adsorption and encapsulation. The organosilicon modified layer blocks the penetration of water molecules, doubly ensuring leaching safety. The above method combines mechanical treatment, chemical treatment and microwave treatment to achieve multi-dimensional coupled activation of the detoxified fly ash, greatly enhancing the activity of the detoxified fly ash.

[0019] The present invention uses a step-by-step activation method of graded grinding-chemical excitation-wet heat curing-microwave activation to enhance the activity of detoxified fly ash, breaking through the bottleneck of a single technology and achieving the dual goals of activity enhancement and heavy metal stabilization. During the detoxification treatment stage of waste incineration fly ash, some inactive substances are separated and removed, and the burning vector is reduced; a large amount of hydrated product gel is formed during the pre-crushing of the product, and the activity is enhanced; by matching the stimulator, the particle size becomes smaller, the specific surface area increases, and the activity is further enhanced; pre-grinding, aging curing and microwave activation strengthen the surface modification of the product, promote chemical reactions, and mineral crystal transformation; the activated product is subjected to secondary ultrafine grinding to reduce static electricity on the powder surface, prevent powder aggregation, form a high specific surface area powder, and the activity is multiplied.

[0020] The integrated activation scheme of the present invention utilizes a combined physical and chemical approach, maximizing the detoxified fly ash activity through the coordinated regulation of specific surface area, microscopic mineral crystal phase, and surface energy. The present invention utilizes a ternary composite activation system of mineral powder, fly ash, and gypsum, which increases activity by over 15% compared to a single activator. The composite activator cost is 40-60% lower than that of soda ash activation. No strong acid or alkaline waste liquid is discharged throughout the process, meeting green building material standards. The energy consumption of graded grinding is reduced by less than 40% compared to traditional processes. DETAILED DESCRIPTION

[0021] The following examples are provided to illustrate preferred embodiments of the present invention. Those skilled in the art will appreciate that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to practice the present invention and, therefore, can be considered preferred embodiments of the present invention. However, those skilled in the art will appreciate from this disclosure that many modifications may be made to the specific embodiments disclosed herein while still achieving the same or similar results without departing from the spirit or scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs, and the disclosures herein and the materials they cite are hereby incorporated by reference. Those skilled in the art will recognize or be able to ascertain, through routine experimentation, many technical equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0023] A method for increasing the activity of detoxified fly ash comprises the following steps: S1. Preheating the waste incineration fly ash in an anaerobic environment at a temperature of 350-400°C for 60-90 minutes for low-temperature thermal decomposition pretreatment, three-stage water washing, and plate-and-frame filter press separation to obtain a detoxified fly ash product with a moisture content of 15-20%. The detoxified fly ash product is crushed to pass a 75 μm sieve with a sieve residue of no more than 15%, thereby obtaining detoxified fly ash; S2. Detoxified fly ash and composite activator are fully mixed in a mass ratio of (70%~85%): (15%~30%) and then pre-ground to a specific surface area of ​​400~500 m 2 / kg; the composite activator is composed of mineral powder, fly ash and gypsum; the mass ratio of mineral powder: fly ash: gypsum in the composite activator is (40%~60%): (30%~50%): (10%~20%); S3, the product after grinding in S2 is subjected to wet heat curing at 50-70°C and humidity ≥90% for 6 hours; S4. A microwave synergist is added to the detoxified fly ash-based active powder after curing, and activated under microwave-assisted heating; the microwave synergist comprises silicon slag powder and ferrous oxide; the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is (90-95%): (5-10%); the amount of the microwave synergist accounts for 5-7% of the mass of the detoxified fly ash-based active powder; the microwave-assisted heating conditions are: microwave frequency 2.45 GHz, power density 3-5 W / g; S5. Cool the powder obtained in step S4, add 0.5% to 1.5% of an organosilicon hydrophobic agent for surface modification, and 0.1% to 0.5% of triethanolamine for auxiliary grinding. Ultrafinely grind the activated material to a specific surface area of ​​600 to 800 m² / kg to obtain detoxified fly ash with enhanced activity.

[0024] The technical solution of the present application will be further described in detail below in conjunction with specific implementation methods.

[0025] Example 1 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5, composite activator compatibility: the detoxified fly ash 75μm sieve undersize in step S4 is mixed with the composite activator in a mass ratio of 80%:20%, and the composite activator is composed of mineral powder, fly ash, and gypsum in a mass ratio of 50%:30%:20%; S6. Mixing and pre-grinding: fully mix the detoxified fly ash and the stimulant components, and pre-grind them to a specific surface area of ​​450 m² / kg; S7. Aging and curing: Curing under the conditions of 60℃ and 90% humidity for 6 hours; S8. Microwave activation: 6% (w / w) microwave synergist was added to the cured detoxified fly ash-based active powder for further microwave activation. The mass ratio of silicon slag powder to ferrous oxide in the microwave synergist was 10:1. The microwave activation conditions were: power density 5 W / g, time 15 min; S9, secondary ultrafine grinding: The powder after S8 is output and cooled, 1% of silicone hydrophobic agent is added for surface modification, 0.5% of triethanolamine is added for auxiliary grinding, and the activated material is further ultrafine ground to a specific surface area of ​​700 m² / kg.

[0026] Example 2 The other steps are the same as those in Example 1, except that: S5, compound stimulant preparation: the detoxified fly ash 75 μm undersize in step S4 is mixed with the compound stimulant in a mass ratio of 85%:15%.

[0027] Example 3 The other steps are the same as those in Example 1, except that: S5, compound stimulant preparation: the detoxified fly ash 75 μm undersize in step S4 is mixed with the compound stimulant in a mass ratio of 75%:25%.

[0028] Example 4 The other steps are the same as those in Example 1, except that: S5, compound stimulant preparation: the detoxified fly ash 75 μm undersize in step S4 is mixed with the compound stimulant in a mass ratio of 70%:30%.

[0029] Example 5 The other steps are the same as those in Example 1, except that: S5, compound stimulant preparation: the detoxified fly ash 75 μm undersize in step S4 is mixed with the compound stimulant in a mass ratio of 65%:35%.

[0030] Example 6 The other steps are the same as those in Example 1, except that: S5, compound stimulant preparation: the detoxified fly ash 75 μm undersize in step S4 is mixed with the compound stimulant in a mass ratio of 90%:10%.

[0031] Example 7 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 50° C. and 90% humidity for 6 hours.

[0032] Example 8 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 70° C. and 90% humidity for 6 hours.

[0033] Example 9 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 80° C. and 90% humidity for 6 hours.

[0034] Example 10 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 60° C. and 80% humidity for 6 hours.

[0035] Example 11 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 60° C. and 85% humidity for 6 hours.

[0036] Example 12 The other steps are the same as those in Example 1, except that: S7, aging and curing: wet heat curing at 60° C. and 95% humidity for 6 hours.

[0037] Example 13 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 15:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0038] Example 14 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 20:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0039] Example 15 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 19:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0040] Example 16 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 9:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0041] Example 17 The other steps are the same as those in Example 1, except that: S8, microwave activation: 5% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0042] Example 18 The other steps are the same as those in Example 1, except that: S8, microwave activation: 4% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0043] Example 19 The other steps are the same as those in Example 1, except that: S8, microwave activation: 8% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0044] Example 20 The other steps are the same as those in Example 1, except that: S8, microwave activation: 7% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 15 min.

[0045] Example 21 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 4 W / g, time 15 min.

[0046] Example 22 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 3 W / g, time 15 min.

[0047] Example 23 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 2 W / g, time 15 min.

[0048] Example 24 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 6 W / g, time 15 min.

[0049] Example 25 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 5 min.

[0050] Example 26 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 10 min.

[0051] Example 27 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 25 min.

[0052] Example 28 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 35 min.

[0053] Example 29 The other steps are the same as those in Example 1, except that: S8, microwave activation: 6% (w / w) microwave synergist is added to the cured detoxified fly ash-based active powder for further microwave synergistic activation, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is 10:1, and the microwave activation conditions are: power density 5 W / g, time 30 min.

[0054] Comparative Example 1 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3. Formation of detoxified fly ash product: The water-ash mixture of step S2 is filtered through a plate and frame filter to obtain detoxified fly ash with a moisture content of 15%.

[0055] Comparative Example 2 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: dechlorination and detoxification of dioxins in fly ash by keeping it warm at 400°C for 80 minutes in the absence of oxygen; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4: Output the detoxified fly ash filter cake, add 1% organic silicon hydrophobic agent for surface modification, and 0.5% triethanolamine for auxiliary grinding. After physical grinding, the specific surface area is 450m 2 / kg.

[0056] Comparative Example 3 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. Composite activator compatibility: the detoxified fly ash 75 μm undersize in step S4 is mixed with a composite activator in a mass ratio of 80%:20%, wherein the composite activator is composed of slag, fly ash, and gypsum in a mass ratio of 50%:30%:20%; S6. Mixing and pre-grinding: fully mix the detoxified fly ash and the components of the composite stimulant, and grind them to a specific surface area of ​​450 m² / kg.

[0057] Comparative Example 4 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. Compound activator preparation: the detoxified fly ash under the 75 μm sieve in step S4 is mixed evenly with the single activator fly ash in a mass ratio of 80%:20%, and ground to a specific surface area of ​​450 m² / kg.

[0058] Comparative Example 5 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. Compound activator preparation: the detoxified fly ash under the sieve of 75 μm in step S4 is mixed evenly with the single activator ore powder in a mass ratio of 80%:20%, and ground to a specific surface area of ​​450 m² / kg.

[0059] Comparative Example 6 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. Microwave activation: 6% (w / w) microwave synergist was added to the detoxified fly ash-based active powder for further microwave activation. The mass ratio of silicon slag powder to ferrous oxide in the microwave synergist was 10:1. The microwave activation conditions were: power density 5 W / g, time 15 min.

[0060] Comparative Example 7 A method for increasing the activity of detoxified fly ash, comprising the following steps: S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. Composite activator compatibility: the detoxified fly ash 75 μm undersize in step S4 is mixed with a composite activator in a mass ratio of 80%:20%, wherein the composite activator is composed of slag, fly ash, and gypsum in a mass ratio of 50%:30%:20%; S6. Mixing and pre-grinding: fully mix the detoxified fly ash and the stimulant components, and pre-grind them to a specific surface area of ​​450 m² / kg; S7. Aging and curing: Curing under the conditions of 60℃ and 90% humidity for 6 hours; S8, secondary ultrafine grinding: The powder after S8 is output and cooled, 1% of silicone hydrophobic agent is added for surface modification, 0.5% of triethanolamine is added for auxiliary grinding, and the activated material is further ultrafine ground to a specific surface area of ​​700 m² / kg.

[0061] Comparative Example 8 S1. Low-temperature thermal decomposition pretreatment of waste incineration fly ash: Dechlorination and detoxification of dioxins in fly ash by keeping it at 400°C in the absence of oxygen for 80 minutes; S2. Three-stage water washing pretreatment of waste incineration fly ash: The waste incineration fly ash after step S1 is subjected to three-stage countercurrent water washing to remove heavy metals, soluble chlorine and salts in the fly ash; S3, formation of detoxified fly ash product: the water-ash mixture of step S2 is subjected to plate and frame filter pressing to obtain a detoxified fly ash filter cake with a moisture content of 15%; S4. Product pre-crushing: Use a vertical crusher to pre-crush the filter cake with low moisture content to a 75um sieve residue of no more than 15%; S5. High-temperature calcination: The detoxified fly ash under 75 μm sieve in step S4 is calcined at 500-800° C. for 1 hour.

[0062] The products prepared in the above examples and comparative examples were subjected to performance testing. The strength activity index of activated detoxified fly ash, used as an active adhesive, was referenced to the S95 grade mineral powder index in GB / T 18046. Product applications include admixtures, mixed materials, and cementitious materials. Therefore, the "Granulated Blast Furnace Slag Powder for Cement, Mortar, and Concrete" (GB / T18046-2024), "Compound Admixtures for Concrete" (JGT486-2015), and "General Portland Cement" (GB175-2023) were comprehensively considered and evaluated.

[0063] The chemical composition of the detoxified fly ash in Example 1 was tested, and the results are shown in Table 1.

[0064] Table 1 Chemical composition of detoxified fly ash

[0065] The results of the activity enhancement performance test of the detoxified fly ash prepared by the schemes of Examples 1 to 29 and Comparative Examples 1 to 8 are shown in Table 2: Table 2 Results of Determination of Detoxification Fly Ash Vitality Enhancement Performance of Examples 1-29 and Comparative Examples 1-8

[0066] We selected the detoxified fly ash whose activity index reached the standard at 7 days and 28 days after the activity was improved as the active adhesive material, and further conducted performance tests on it as described in Table 3. The results of the environmental protection index tests are shown in Table 4.

[0067] Table 3 Performance test results of detoxified fly ash that meets the standards as active adhesive

[0068] Table 4 Determination results of environmental protection index of detoxified fly ash that meets the standards as active adhesive

[0069] Among the above indicators, water demand ratio is an important indicator reflecting the water consumption of materials. It is a technical indicator to assess whether it has water reduction function. The better the water reduction function, the more significantly it can reduce the mixing water consumption of materials, and the higher the engineering utilization value.

[0070] The sulfur trioxide content will affect the stability of cement and other products, causing adverse consequences such as expansion and cracking of the products; it will also affect the strength of concrete.

[0071] The fluidity ratio is a measure of the flow properties of materials during transportation and accumulation.

[0072] The results show that the percentage of fly ash treatment products and composite activators has a comprehensive impact on the activity index and other performance indicators. The optimal addition ratio of fly ash treatment products and composite activators is (70-85%): (15-30%). The aging and curing conditions after chemical excitation and microwave activation conditions have a certain influence on the activity index. Considering the decomposition temperature of ettringite not exceeding 70°C, the optimal aging and curing conditions are 50-70°C, humidity ≥90%, and time 4-8h. The proportion and dosage of microwave synergist have little effect.

[0073] Detoxification fly ash is mainly composed of alkaline calcium-based materials. Under the stimulation of silica, aluminum and sulfate, it will form gels such as CSH, CAH, CASH with early (7d) active strength and late (28d) active gel mainly composed of AFt (ettringite). Within a certain range, increasing the amount of detoxification fly ash will promote the early active strength, but is not conducive to the formation of late strength.

[0074] The control of chloride ions in this system mainly involves the formation of hydrated calcium chloroaluminate, which consumes most of the chloride ions in the material. Secondly, the dense matrix gel composed of various products such as AFt (ettringite) further physically isolates the chloride ions.

[0075] The ratio of detoxified fly ash to composite activator affects the performance indicators of active adhesive materials, such as water demand ratio, fluidity ratio, and initial setting time ratio, mainly due to the changes in the Si / Ca / Al ratio in the system and the changes in the physical properties caused by the production of gel products.

[0076] Heavy metals can be adsorbed by the chemical binding sites in the CSH gel product. In addition, the AFt phase product generated in the system is a layered crystal with chemical binding sites between its layers, which has the ability to adsorb oxygen anion heavy metals. Its hydration product will undergo a series of physical and chemical reactions with heavy metals, such as physical encapsulation, chemical adsorption, ion exchange, and precipitation reaction, so that the heavy metals are physically and chemically bound in the gel matrix. At the same time, the formation of the gel phase will promote the migration of heavy metals (Pb, Cr, Zn, etc.) in fly ash from an unstable state to a stable state.

[0077] Aging accelerates hydration and gel formation. Temperatures above 70°C cause the generated AFt to decompose, releasing more free chlorine and limiting the application scenarios of active adhesive products. Microwave enhancers do not significantly affect the activity or other properties of active adhesives. They primarily assist in microwave activation and improve its efficiency. The power density and duration of microwave activation have a direct and significant impact on the activation effect. Based on experimental data, a power density of 3-5 W / g and a duration of 10-30 minutes have shown the best activity enhancement results.

[0078] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that such equivalents also fall within the scope of the present application.

Claims

1. A method for increasing the activity of detoxified fly ash, characterized in that: The steps include: S1. The waste incineration fly ash is subjected to low-temperature thermal decomposition pretreatment, three-stage water washing, and plate-and-frame filter press separation to obtain a detoxified fly ash product, and the detoxified fly ash product is crushed and sieved to obtain detoxified fly ash; S2. Detoxified fly ash and a composite activator are thoroughly mixed in a mass ratio of (70% to 85%): (15% to 30%) and then pre-ground to a specific surface area of ​​400 to 500 m² / kg; the composite activator is composed of mineral powder, fly ash, and gypsum; S3, the product after grinding in S2 is subjected to wet heat curing at 50-70°C and humidity ≥90% for 6 hours; S4, adding a microwave synergist to the detoxified fly ash-based active powder after curing, and activating it under microwave-assisted heating; the microwave synergist comprises silicon slag powder and ferrous oxide; S5. Cool the powder obtained in step S4, add 0.5% to 1.5% of an organosilicon hydrophobic agent for surface modification, and 0.1% to 0.5% of triethanolamine for auxiliary grinding. Ultrafinely grind the activated material to a specific surface area of ​​600 to 800 m² / kg to obtain detoxified fly ash with enhanced activity.

2. The method for increasing the activity of detoxified fly ash according to claim 1, characterized in that: In step S2, the mass ratio of mineral powder: fly ash: gypsum in the composite activator is (40%~60%): (30%~50%): (10%~20%).

3. The method for increasing the activity of detoxified fly ash according to claim 1, characterized in that: In step S4, the mass ratio of silicon slag powder to ferrous oxide in the microwave synergist is (90-95%): (5-10%).

4. The method for increasing the activity of detoxified fly ash according to claim 3, characterized in that: In step S4, the amount of the microwave synergist used accounts for 5-7% of the mass of the detoxified fly ash-based active powder.

5. The method for increasing the activity of detoxified fly ash according to claim 4, characterized in that: In step S4, the microwave-assisted heating conditions are: microwave frequency 2.45 GHz, power density 3-5 W / g.

6. The method for increasing the activity of detoxified fly ash according to claim 1, characterized in that: In step S1, the low-temperature thermal decomposition pretreatment method is: keeping the temperature at 350-400° C. for 60-90 minutes in the absence of oxygen to dechlorinate and detoxify dioxins in the fly ash.

7. The method for increasing the activity of detoxified fly ash according to claim 1, characterized in that: In step S1, the detoxified fly ash product obtained by plate and frame filter pressing has a moisture content of 15-20%.

8. The method for increasing the activity of detoxified fly ash according to claim 1, characterized in that: In step S1, the detoxified fly ash product is crushed and sieved under the condition of passing through a 75 μm sieve with a sieve residue of no more than 15%.

9. Detoxified fly ash with enhanced activity prepared according to the method according to any one of claims 1 to 8.

10. The use of the detoxified fly ash with enhanced activity according to claim 9, characterized in that: The detoxified fly ash with enhanced activity is used as a composite admixture in the production of concrete, as an active admixture in the production of cement, as a low-carbon cementitious material to replace 30-50% of cement in the production of cement products, and as an inorganic binder in roadbed materials to stabilize gravel or solidify soil.

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