A method for solidifying and stabilizing waste incineration fly ash using construction waste

Abstract

The present application relates to the technical field of waste incineration fly ash disposal, and in particular to a method for solidifying and stabilizing waste incineration fly ash using construction waste. A method for solidifying and stabilizing waste incineration fly ash using construction waste comprises the following steps: mixing waste incineration fly ash and construction waste and then melting them at high temperature, then cooling the melt to obtain a geopolymer block material; finely grinding the geopolymer block material to a mass fraction of ≥75% of ‑45µm and a specific surface area of ​​≥450m 2 / kg, a powdery geopolymer material is obtained; the powdery geopolymer material, the waste incineration fly ash and the activator are mixed evenly, and the water-cement ratio is 0.4-0.7 to obtain a fly ash solidified body. The present invention uses construction waste and fly ash generated in the process of waste incineration to prepare geopolymer cement material, and replaces cement and chelating agent in the solidification and stabilization process to solidify and stabilize the waste incineration fly ash; it not only saves the consumption of cement and chelating agent, but also solves the storage problem of construction waste, and achieves the purpose of treating waste with waste.

Description

Technical Field

[0001] The present application relates to the technical field of waste incineration fly ash disposal, and in particular to a method for solidifying and stabilizing waste incineration fly ash by utilizing construction waste. Background Art

[0002] Waste incineration fly ash refers to fine particles collected from air pollution equipment, generally collected by cyclone dust collectors, electrostatic precipitators or bag filters. Waste incineration fly ash produced by grate incinerators accounts for 3-5% of the amount of domestic waste incinerated; waste incineration fly ash produced by fluidized bed incinerators accounts for more than 10% of the amount of domestic waste incinerated. Waste incineration fly ash is defined as hazardous waste because it gathers pollutants generated by waste incineration, mainly inorganic salts, heavy metals and dioxins. Incineration fly ash must be specially managed and disposed of.

[0003] At present, the solidification and stabilization technologies include cement solidification and stabilization technology, chelating agent solidification and stabilization technology and cement-chelating agent solidification and stabilization technology. All three technologies use cement, chelating agent, etc., resulting in high production costs.

[0004] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a method for solidifying and stabilizing waste incineration fly ash using construction waste, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0006] In order to achieve the above objectives, this application provides the following technical solutions:

[0007] A method for solidifying and stabilizing waste incineration fly ash using construction waste, comprising the following steps:

[0008] (1) Mixing waste incineration fly ash and construction waste to obtain a mixture; placing the mixture in a muffle furnace or a smelting furnace for high-temperature melting; after the melting is completed, taking the melt out of the furnace, and cooling it naturally or by water quenching to obtain a geopolymer block material;

[0009] (2) Grind the geopolymer block material using a ball mill or rod mill to a mass fraction of -45µm ≥ 75% and a specific surface area ≥ 450m 2 / kg, and obtain powdery geopolymer material;

[0010] (3) The powdered geopolymer material, waste incineration fly ash and activator are mixed evenly with a water-to-ash ratio of 0.4 to 0.7 to obtain a fly ash solidified body.

[0011] Preferably, in step (1), the construction waste includes waste concrete, slag, and waste bricks, and the main components of the construction waste are as follows: CaO 10-30%, SiO2 25-70%, Al2O3 5-20%, MgO 4-10%, Na2O 0.1-5%, and SO2 0.01-1%.

[0012] Preferably, in step (1), the main element contents of the waste incineration fly ash are as follows: Ca 30-70%, Si 1-10%, Cl 25-35%, Na 1-10%, K 1-10%, and C 1-15%.

[0013] Preferably, in step (1), the mass percentages of the waste incineration fly ash and construction waste are 30-60% and 40-70% respectively.

[0014] Preferably, in step (1), the melting temperature is 1100-1350° C., and the melting time is 40-150 min.

[0015] Further preferably, in step (2), the powdered geopolymer material is an amorphous material composed of silicon oxide tetrahedrons and aluminum oxide tetrahedrons.

[0016] More preferably, in step (3), the alkaline activator is one or more of NaOH, Ca(OH)2, and water glass. The alkaline activator is an alkaline substance that can activate the powdered geopolymer material to reconstruct it to form a new silicon (aluminum) oxygen tetrahedron structure and make the powder gel.

[0017] Still more preferably, in step (3), the mass percentage of the powdered geopolymer material is 35-50%, the mass percentage of the waste incineration fly ash is 45-60%, and the mass percentage of the activator is 2-10%.

[0018] Still more preferably, in step (3), the compressive strength of the fly ash solidified body is 4-25 MPa after 3 days, and 5-45 MPa after 28 days.

[0019] Beneficial effects:

[0020] The present invention utilizes two kinds of solid wastes, namely, construction waste and fly ash generated in the process of waste incineration, to prepare oligomer cement materials, and replaces cement and chelating agent in the solidification and stabilization process to solidify and stabilize the fly ash of waste incineration; it not only saves the consumption of resources such as cement and chelating agent, but also solves the storage problem of construction waste, thereby achieving the purpose of treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. Among them:

[0022] Figure 1 This is a flow chart of the method for solidifying and stabilizing waste incineration fly ash using construction waste in this application. DETAILED DESCRIPTION

[0023] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the embodiments of the present invention should belong to the scope of protection of the embodiments of the present invention.

[0024] Example 1

[0025] A method for solidifying and stabilizing waste incineration fly ash using construction waste, comprising the following steps:

[0026] 30% by mass of waste incineration fly ash and 70% by mass of construction waste were mixed evenly and placed in a muffle furnace, melted at 1350°C for 40 minutes, and the melt was taken out of the muffle furnace and quenched with water to obtain a geopolymer block material. The geopolymer block material was finely ground to a mass fraction of 77.12% and a specific surface area of ​​461m2 at -45µm. 2

[0027] / kg of powdered geopolymer material, which is an amorphous material composed of silicon oxide tetrahedron and aluminum oxide tetrahedron. 35% of powdered geopolymer material, 55% of waste incineration fly ash, 7% of water glass and 3% of NaOH are mixed. After mixing, the water-cement ratio is 0.7 to form a fly ash solid body. The compressive strength of the fly ash solid body is 3.12Mpa after 3 days and 7.81Mpa after 28 days. The flow chart is as follows Figure 1 The toxicity leaching test was carried out on the solidified fly ash, and the toxicity leaching test was carried out in accordance with the standard of "Solid Waste Leaching Toxicity Leaching Method Acetate Buffer Solution Method" (HJ / T300-2007). The results of the toxicity leaching test are shown in Table 1. The main element contents of waste incineration fly ash are as follows: Ca 35%, Si 3%, Cl 25%, Na 11%, K 9%, C 5%.

[0028] The main components of construction waste are as follows: CaO 18.71%, SiO2 50.31%, Al2O3 14.58%, MgO 7.54%, Na2O 1.23%, SO2 0.05%.

[0029] Example 2

[0030] A method for solidifying and stabilizing waste incineration fly ash using construction waste, comprising the following steps:

[0031] 50% by mass of waste incineration fly ash and 50% by mass of construction waste were mixed evenly and placed in a muffle furnace, melted at 1200°C for 90 minutes, and the melt was taken out of the muffle furnace and cooled naturally to obtain a geopolymer block material. The geopolymer block material was finely ground to a mass fraction of 85.19% and a specific surface area of ​​486m -45µm. 2 / kg of powdered geopolymer material, which is an amorphous material composed of silicon oxide tetrahedron and aluminum oxide tetrahedron. 50% of the geopolymer material, 47% of the waste incineration fly ash and 3% of NaOH were mixed, and after mixing, the water-cement ratio was 0.5 to form a fly ash solid body. The compressive strength of the fly ash solid body was 18Mpa after 3 days, and the compressive strength was 39Mpa after 28 days. The fly ash solid body was subjected to a toxic leaching test, and the toxic leaching test was carried out in accordance with the standard "Solid Waste Leaching Toxicity Leaching Method Acetic Acid Buffer Solution Method" (HJ / T300-2007). The results of the toxic leaching test are shown in Table 1. The main element contents of waste incineration fly ash are as follows: Ca41%, Si 8%, Cl 30%, Na 4%, K 5%, C 9%.

[0032] The main components of construction waste are as follows: CaO 12.15%, SiO2 63.34%, Al2O3 10.22%, MgO 8.29%, Na2O 1.63%, SO2 0.14%.

[0033] Example 3

[0034] A method for solidifying and stabilizing waste incineration fly ash using construction waste, comprising the following steps:

[0035] 60% by mass of waste incineration fly ash and 40% by mass of construction waste were mixed evenly and placed in a muffle furnace, melted at 1100°C for 150 minutes, and the melt was taken out of the muffle furnace and quenched with water to obtain a geopolymer block material. The geopolymer block material was finely ground to a mass fraction of 89.14% and a specific surface area of ​​523m2 at -45µm. 2 / kg of powdered geopolymer material, which is an amorphous material composed of silicon oxide tetrahedron and aluminum oxide tetrahedron. 45% of geopolymer material, 50% of waste incineration fly ash, 3% of water glass and 2% of Ca(OH)2 are mixed, and after mixing, the water-cement ratio is 0.4 to form a fly ash solid body. The compressive strength of the fly ash solid body after 3 days is 8.12Mpa, and the compressive strength after 28 days is 26.37Mpa. The fly ash solid body is subjected to a toxic leaching test, and the toxic leaching test refers to the standard of "Solid Waste Leaching Toxicity Leaching Method Acetic Acid Buffer Solution Method" (HJ / T300-2007). The results of the toxic leaching test are shown in Table 1. The main element contents of waste incineration fly ash are as follows: Ca 52%, Si 5%, Cl 21%, Na 8%, K 4%, C 12%.

[0036] The main components of construction waste are as follows: CaO 24.19%, SiO2 46.33%, Al2O3 19.35%, MgO 4.13%, Na2O 2.71%, and SO2 0.08%.

[0037] Table 1 Toxicity leaching results of examples

[0038]

[0039] As can be seen from Table 1, the heavy metals Pb, Zn, Cu, Cd, Cr, As, etc. in Examples 1-3 are all lower than the toxicity standard of the Landfill Pollution Control Standard (GB 16889-2008), which shows that the curing effect of the present invention is very good.

[0040] The fly ash in Example 1 was solidified and stabilized using cement, chelating agent, and chelating agent-cement combined solidification, and the measured leaching toxicity results are shown in Table 2.

[0041] Table 2 Leaching toxicity results (unit: mg / L)

[0042]

[0043] As can be seen from Table 2, the curing effect of the present invention is better than that of the chelating agent, and is similar to the curing effect of cement curing and combined curing.

[0044] The present invention utilizes two kinds of solid wastes, namely, construction waste and fly ash generated in the process of waste incineration, to prepare oligomer cement materials, and replaces cement and chelating agent in the solidification and stabilization process to solidify and stabilize the fly ash of waste incineration; it not only saves the consumption of resources such as cement and chelating agent, but also solves the storage problem of construction waste, thereby achieving the purpose of treating waste with waste.

[0045] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0046] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for solidifying and stabilizing waste incineration fly ash using construction waste, characterized in that: The following steps are involved: (1) Mixing waste incineration fly ash and construction waste to obtain a mixture; placing the mixture in a muffle furnace or a smelting furnace for high-temperature melting; after the melting is completed, taking the melt out of the furnace, and cooling it naturally or by water quenching to obtain a geopolymer block material; The main components of the construction waste are as follows: CaO 10-30%, SiO2 25-70%, Al2O3 5-20%, MgO 4-10%, Na2O 0.1-5, SO2 0.01-1%; The main element contents of the waste incineration fly ash are as follows: Ca 30-70%, Si 1-10%, Cl 25-35%, Na 1-10%, K 1-10%, C 1-15%; The melting temperature is 1100-1350°C; (2) Grind the geopolymer block material using a ball mill or rod mill to a mass fraction of -45µm ≥ 75% and a specific surface area ≥ 450m 2 / kg, to obtain a powdery geopolymer material; the powdery geopolymer material is an amorphous material composed of silicon-oxygen tetrahedrons and aluminum-oxygen tetrahedrons; the powdery geopolymer material replaces cement and chelating agent in the solidification and stabilization process to solidify and stabilize the waste incineration fly ash; (3) Powdered geopolymer material, waste incineration fly ash and an activator are mixed evenly with a water-to-cement ratio of 0.4 to 0.7 to obtain a fly ash solidified body; the fly ash solidified body has a compressive strength of 4 to 25 MPa after 3 days and a compressive strength of 5 to 45 MPa after 28 days.

2. The method for solidifying and stabilizing waste incineration fly ash using construction waste according to claim 1, characterized in that: In step (1), the construction waste includes waste concrete, slag and waste bricks.

3. The method for solidifying and stabilizing waste incineration fly ash using construction waste according to claim 1, characterized in that: In step (1), the mass percentages of the waste incineration fly ash and construction waste are 30-60% and 40-70% respectively.

4. The method for solidifying and stabilizing waste incineration fly ash using construction waste according to any one of claims 1 to 3, characterized in that: In step (1), the melting time is 40 to 150 minutes.

5. The method for solidifying and stabilizing waste incineration fly ash using construction waste according to claim 1, characterized in that: In step (3), the activator is one or more of NaOH, Ca(OH)2, and water glass.

6. The method for solidifying and stabilizing waste incineration fly ash using construction waste according to claim 5, characterized in that: In step (3), the mass percentage of the powdered geopolymer material is 35-50%, the mass percentage of the waste incineration fly ash is 45-60%, and the mass percentage of the activator is 2-10%.

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