Fly ash dechlorination method

Abstract

The invention discloses a fly ash dechlorination method which comprises the following steps: (1) crushing, grinding and drying a porcelain block to obtain porcelain powder; (2) drying and grinding the household garbage incineration fly ash to obtain fly ash powder; (3) the treated porcelain powder and fly ash powder are mixed, a solid mixture is obtained, and the addition amount of the porcelain powder accounts for 10-50% of the mass of the fly ash; and (4) roasting the solid mixture at 900-1100 DEG C for 1-10 hours to obtain the dechlorinated fly ash. According to the fly ash dechlorination method, the porcelain powder is used as an auxiliary agent for fly ash dechlorination, and the main components of the porcelain powder highly coincide with the use requirements of fly ash as a building material, so that the physical and chemical properties of the fly ash used for the building material are effectively improved, the purpose of treating waste with waste is achieved, and the use of chemical reagents is reduced. The fly ash auxiliary agent can effectively reduce the reaction temperature of fly ash heat treatment, and plays a role in reducing energy consumption. The method is simple and efficient, the final heavy metal leaching rate of the fly ash can be reduced, and the selectivity of follow-up process treatment is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource utilization of household garbage incineration fly ash, and in particular to a fly ash dechlorination method. BACKGROUND

[0002] Porcelain powder, mainly from waste bases, waste glaze, polishing waste residues and the like in the ceramic production process, is one of the main solid wastes in the ceramic industry. Porcelain powder itself has a certain application prospect in the building material field, but the application of ceramic waste residues in the building material field has technical difficulties such as "high cost and unstable performance", which restricts its large-scale transformation. Porcelain powder does not belong to hazardous waste, but its direct discharge will also seriously pollute the environment. At present, due to technical and financial limitations, the treatment and utilization rate of waste residues in the domestic ceramic industry is relatively low.

[0003] Fly ash, as one of the by-products of waste incineration technology, its production gradually increases with the large-scale application of waste incineration in China. Fly ash contains a large amount of heavy metals (Zn, Cu, Pb, Cd, Cr), persistent organic pollutants (dioxins, etc.) and soluble salts, and is therefore defined as hazardous waste and listed in the National Hazardous Waste List, No. HW18. Although fly ash is defined as hazardous waste, it has great resource utilization potential due to the total proportion of elements such as Ca, Si, Al, Fe and Mg reaching 50%-70%.

[0004] The main obstacle to the resource utilization of fly ash is the high content of heavy metals, dioxins and chlorine salts in fly ash. High content of chlorine salts can seriously affect the strength and hardness of concrete, hinder the cement hydration process and increase the risk of heavy metal leaching in the solidified body. Therefore, harmless treatment and deep dechlorination to reduce the chlorine salt content in fly ash are the first step in fly ash utilization. The main methods of fly ash harmless treatment and disposal are separation and extraction, solidification / stabilization and thermal treatment technology. Compared with other methods, thermal treatment has the advantages of short treatment period, large treatment capacity, high dioxin degradation effect, good heavy metal solidification effect, small leaching risk and large amount of chlorine salt volatilization. The common fly ash thermal treatment temperature needs to reach about 1200-1300℃ to complete the overall volatilization of chlorine salts, and there will still be a part of insoluble chlorine, which will hinder its further application. Therefore, a certain modifier needs to be added to reduce the temperature required for fly ash thermal treatment and promote the conversion of insoluble chlorine in fly ash. The main modifiers are SiO2, Al2O3, Na2CO3 and B2O3. Porcelain powder, which is mainly composed of silicates and aluminum oxide, is a perfect modifier choice. The part of iron oxide and other substances contained in porcelain powder can also optimize the composition of fly ash after thermal treatment. Therefore, porcelain powder can be used as a modifier for fly ash dechlorination, which can realize the resource utilization of fly ash and turn waste into treasure.

[0005] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in any country in the world. SUMMARY

[0006] The present application aims to provide a method for dechlorination of fly ash, so as to overcome the shortcomings of traditional thermal chemical reagent usage, high reaction temperature energy consumption, long process flow and the like.

[0007] To achieve the above-mentioned purpose, the present application provides a method for dechlorination of fly ash, comprising the following steps:

[0008] (1) crushing and grinding the porcelain block, drying to obtain porcelain powder;

[0009] (2) drying and grinding the household waste incineration fly ash to obtain fly ash powder;

[0010] (3) mixing the treated porcelain powder and fly ash powder to obtain a solid mixture, wherein the addition amount of the porcelain powder accounts for 10-50% of the mass of the fly ash;

[0011] (4) calcining the solid mixture at 900-1100℃ for 1-10h to obtain dechlorinated fly ash.

[0012] Preferably, in the above technical solution, the step (1) is that the porcelain powder is ground and then sieved through a 80-200 mesh sieve, and dried at a temperature of 70-90℃ for 1-5h.

[0013] Preferably, in the above technical solution, the step (2) is that the fly ash is dried at a temperature of 70-90℃ for 10-48h, and then ground and sieved through a 80-200 mesh sieve.

[0014] Preferably, in the above technical solution, the step (3) is that the addition amount of the porcelain powder accounts for 20-40% of the mass of the fly ash.

[0015] Preferably, in the above technical solution, the step (3) is that the addition amount of the porcelain powder accounts for 30% of the mass of the fly ash.

[0016] Preferably, in the above technical solution, the step (4) is that the calcination is carried out at a temperature rising rate of 3-6℃ / min, and the temperature is raised to a final temperature of 900-1100℃.

[0017] An application of porcelain powder in dechlorination of fly ash, wherein the porcelain powder is used for dechlorination of fly ash, and the method for dechlorination of fly ash is as described above.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: The fly ash dechlorination method of this invention uses ceramic powder as an additive for fly ash dechlorination. Its main components highly overlap with the requirements for fly ash as a building material, effectively increasing the physicochemical properties of fly ash used in building materials, achieving waste-to-waste treatment, and reducing the use of chemical reagents. Simultaneously, the fly ash additive can effectively lower the reaction temperature of fly ash heat treatment, thus reducing energy consumption. Compared with traditional methods, this method is simple and efficient, and can also reduce the final heavy metal leaching rate of fly ash, offering selectivity in subsequent processing. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the fly ash dechlorination method of the present invention. Detailed Implementation

[0020] The following detailed description of specific embodiments is provided in conjunction with the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0021] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" will be understood to include the stated elements or components without excluding other elements or other components. Unless otherwise specified, all raw materials and reagents used in the embodiments are commercially available. Example 1

[0022] A method for dechlorinating fly ash is as follows:

[0023] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat, and ceramic powder was added at a rate of 30% of the fly ash mass. The ceramic powder and fly ash were mixed evenly and then placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1000℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0024] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 95.53%. Example 2

[0025] A method for dechlorinating fly ash is as follows:

[0026] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat, and ceramic powder was added at a rate of 30% of the fly ash mass. The ceramic powder and fly ash were mixed evenly and then placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 900℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0027] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 78.53%. Example 3

[0028] A method for dechlorinating fly ash is as follows:

[0029] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat, and ceramic powder was added at a rate of 10% of the fly ash mass. The ceramic powder and fly ash were mixed evenly and placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1000℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0030] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 73.05%. Example 4

[0031] A method for dechlorinating fly ash is as follows:

[0032] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat, and ceramic powder was added at a rate of 50% of the fly ash mass. The ceramic powder and fly ash were mixed evenly and then placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1000℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0033] The sample was removed and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was then determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 96.66%. Example 5

[0034] A method for dechlorinating fly ash is as follows:

[0035] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat, and ceramic powder was added at a rate of 30% of the fly ash mass. The ceramic powder and fly ash were mixed evenly and then placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1000℃, and the holding time was 3 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0036] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 91.65%. Comparative Example 1

[0037] A method for dechlorinating fly ash is as follows:

[0038] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat and placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 800℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0039] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 17.32%. Comparative Example 2

[0040] A method for dechlorinating fly ash is as follows:

[0041] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat and placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 900℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0042] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 25.45%. Comparative Example 3

[0043] A method for dechlorinating fly ash is as follows:

[0044] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat and placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1000℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0045] The sample was removed and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was then determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 67.79%. Comparative Example 4

[0046] A method for dechlorinating fly ash is as follows:

[0047] The fly ash came from a municipal solid waste incineration plant in Nanning, Guangxi. The incineration plant uses a mechanical grate furnace, and the chlorine content in the fly ash reached 21.79%. The fly ash was dried in an 80℃ oven for 24 hours. The dried fly ash was then passed through a 100-mesh sieve to obtain dry fly ash (moisture content 5%). 7g of fly ash was added to a ceramic boat and placed in a muffle furnace for heat treatment. The heating rate was 5℃ / min, the final temperature was 1100℃, and the holding time was 5 hours. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain the sample.

[0048] The sample was taken out and passed through a 200-mesh sieve. The chlorine content in the calcined fly ash was determined using X-ray fluorescence spectrometry (XRF). The total chlorine removal rate in the fly ash was 82.26%.

[0049] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for dechlorinating fly ash, characterized in that, Includes the following steps: (1) Crush and grind the porcelain blocks, dry them, and obtain porcelain powder; (2) Dry and grind the fly ash from municipal solid waste incineration to obtain fly ash powder; (3) The treated ceramic powder and fly ash powder are mixed to obtain a solid mixture, wherein the amount of ceramic powder added accounts for 10-50% of the mass of fly ash; (4) The solid mixture is calcined at 900-1100℃ for 1-10h to obtain dechlorinated fly ash.

2. The method for dechlorinating fly ash according to claim 1, characterized in that, Step (1) After grinding the porcelain powder, pass it through an 80-200 mesh sieve and dry it at a temperature of 70-90℃ for 1-5 hours.

3. The method for dechlorinating fly ash according to claim 1, characterized in that, Step (2) Dry the fly ash at 70-90℃ for 10-48h, then grind it and pass it through an 80-200 mesh sieve.

4. The method for dechlorinating fly ash according to claim 1, characterized in that, Step (3) The amount of ceramic powder added accounts for 20-40% of the fly ash mass.

5. The method for dechlorinating fly ash according to claim 1, characterized in that, Step (3) The amount of ceramic powder added accounts for 30% of the fly ash mass.

6. The method for dechlorinating fly ash according to claim 1, characterized in that, Step (4) calcination involves heating at a rate of 3-6℃ / min until the final temperature of 900-1100℃ is reached.

7. An application of ceramic powder in fly ash dechlorination, characterized in that, The application uses ceramic powder for fly ash dechlorination, and the method for fly ash dechlorination is as described in any one of claims 1-6.

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