Waste incineration fly ash mineralization carbon sequestration and heavy metal solidification coupled method and waste incineration solidified body

Abstract

The invention relates to the technical field of solid waste treatment and carbon sequestration and emission reduction, and discloses a method for mineralizing, carbon sequestration and heavy metal solidification of waste incineration fly ash and a waste incineration fly ash solidified body. The waste incineration fly ash mineralization carbon sequestration and heavy metal solidification coupled method comprises the steps that a fly ash solidified green body is prepared, specifically, waste incineration fly ash and cement serve as raw materials, water is added, pouring forming is conducted after uniform stirring, demolding is conducted after standing, and the fly ash solidified green body is prepared; mineralization is conducted, specifically, the fly ash solidified green body is placed in a high-pressure kettle to be subjected to mineralization reaction through pure CO2, and a waste incineration fly ash solidified body is prepared; wherein the addition amount of the waste incineration fly ash is 50wt.%-60wt.%, the addition amount of the cement is 40wt.%-50wt.%, the total addition amount of the waste incineration fly ash and the cement is 100wt.%, and the mass ratio of water to ash is 0.3-0.45. According to the method, CO2 is used for mineralizing the waste incineration fly ash solidified body, harmlessness of the waste incineration fly ash can be achieved, especially solidification of typical heavy metal can be achieved, and compared with a traditional solidification method, a chelating agent can be saved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste disposal and carbon fixation and emission reduction, and relates to a method for mineralizing carbon fixation and coupling heavy metal solidification of waste incineration fly ash and a waste incineration fly ash solidified body prepared by the method. Background Art

[0002] At present, the harmless treatment technologies for fly ash from the incineration of domestic waste mainly include cement solidification technology, melt solidification technology, and chemical agent stabilization technology. The above technologies can effectively stabilize and solidify heavy metals in fly ash from waste incineration, and can achieve harmless utilization of fly ash under certain conditions, but they are generally costly and have poor long-term stability. CO2 mineralization, as a carbon fixation technology, has received increasing attention in recent years. Therefore, the present invention utilizes the characteristics of waste incineration fly ash that is rich in Ca, and develops a technology for fixing CO2 and simultaneously achieving the solidification of heavy metals, so as to achieve the harmlessness of waste incineration fly ash and CO2 capture, solidification and storage in one. Summary of the invention

[0003] One of the purposes of the present invention is to provide a method for mineralizing and carbon fixing of waste incineration fly ash coupled with heavy metal solidification, which can achieve the harmlessness and carbon fixing performance of waste incineration fly ash.

[0004] A second object of the present invention is to provide a solidified body of waste incineration fly ash.

[0005] In one aspect, the present invention provides a method for mineralizing and carbonizing fly ash from waste incineration coupled with heavy metal solidification, comprising:

[0006] Preparation of fly ash solidified green body: using waste incineration fly ash and cement as raw materials, adding water, stirring evenly and then pouring into shape, and demoulding after standing to obtain fly ash solidified green body;

[0007] Mineralization: The fly ash solidified body is placed in an autoclave and subjected to mineralization reaction using pure CO2 to obtain a solidified body of waste incineration fly ash;

[0008] Among them, the addition amount of waste incineration fly ash is 50%-60%, the addition amount of cement is 40%-50%, the total addition amount of waste incineration fly ash and cement is 100%, and the water-cement mass ratio is 0.3-0.45.

[0009] The present invention uses waste incineration fly ash and cement as main raw materials, obtains fly ash solidification blank by adjusting appropriate ratio, adding water to mix, and pouring, and then obtains waste incineration fly ash solidification body through mineralization reaction. Through this method, CO2 and heavy metal solidification can be achieved simultaneously, and the leaching toxicity of heavy metals in the waste incineration fly ash solidification body can be reduced. Compared with the traditional solidification method, chelating agent can be saved.

[0010] As a preferred solution of the method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification, the standing time is 18h-24h.

[0011] As a preferred solution of the method for mineralization and carbon fixation coupled with heavy metal solidification of waste incineration fly ash, the temperature of the mineralization reaction is 40°C-100°C.

[0012] As a preferred solution of the method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification, the pressure of the mineralization reaction is 1.2MPa-1.6MPa.

[0013] As a preferred solution of the method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification, the mineralization reaction time is 4h-10h.

[0014] On the other hand, a solidified body of waste incineration fly ash is provided, which is prepared by the method of mineralizing carbon fixation and coupling heavy metals of waste incineration fly ash.

[0015] The present invention has the following beneficial effects:

[0016] (1) The present invention utilizes CO2 to mineralize solidified waste incineration fly ash, thereby achieving harmlessness of waste incineration fly ash, especially solidification of typical heavy metals (Pb, Ni, Cr, Cd, As). Compared with the traditional solidification method, chelating agent can be saved.

[0017] (2) The present invention utilizes CO2 to mineralize the solidified body of waste incineration fly ash, thereby achieving the capture and solidification of CO2. The solidified carbon can be as high as 12.5% ​​or more, with outstanding carbon fixation and carbon reduction efficiency. Under certain conditions, the solidified body can be used to prepare building materials products.

[0018] (3) The waste incineration fly ash mineralization coupled heavy metal solidification method involved in the present invention has very obvious environmental benefits and prospects. DETAILED DESCRIPTION

[0019] The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention.

[0020] Example 1

[0021] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (50 wt.%), add a certain amount of cement (50 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0022] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure of 1.2MPa, mineralization time of 8h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0023] Example 2

[0024] (1) Preparation of solidified blanks from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.38), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0025] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 100°C, mineralization pressure of 1.2MPa, mineralization time of 8h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0026] Example 3

[0027] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (55 wt.%), add a certain amount of cement (45 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.45), stir well, cast into shape using a mold, and demold after standing for 20 hours.

[0028] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 80°C, mineralization pressure of 1.5MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0029] Example 4

[0030] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (50 wt.%), add a certain amount of cement (50 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.45), stir well, cast into shape using a mold, and demold after standing for 20 hours.

[0031] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 80°C, mineralization pressure of 1.6MPa, mineralization time of 10h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0032] Example 5

[0033] (1) Preparation of solidified blanks from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.38), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0034] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave and CO2 is introduced for mineralization reaction. Mineralization reaction conditions: 70°C, mineralization pressure of 1.4MPa, mineralization time of 6h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0035] Example 6

[0036] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.36), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0037] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 80°C, mineralization pressure of 1.6MPa, mineralization time of 10h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0038] Example 7

[0039] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0040] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure of 1.6MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0041] Comparative Example 1

[0042] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (80 wt.%), add a certain amount of cement (20 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0043] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure of 1.6MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0044] Comparative Example 2

[0045] (1) Preparation of solidified blanks from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.50), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0046] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure of 1.2MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0047] Comparative Example 3

[0048] (1) Preparation of solidified blanks from waste incineration fly ash: Use waste incineration fly ash as the main raw material (70 wt.%), add a certain amount of cement (30 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.35), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0049] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 40°C, mineralization pressure of 1.4MPa, mineralization time of 8h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0050] Comparative Example 4

[0051] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0052] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 35°C, mineralization pressure of 1.6MPa, mineralization time of 15h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0053] Comparative Example 5

[0054] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0055] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 110°C, mineralization pressure of 1.6MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0056] Comparative Example 6

[0057] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0058] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure of 1.75MPa, mineralization time of 4h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0059] Comparative Example 7

[0060] (1) Preparation of solidified green bodies from waste incineration fly ash: Use waste incineration fly ash as the main raw material (60 wt.%), add a certain amount of cement (40 wt.%), mix well, add a certain amount of water (water / ash mass ratio = 0.4), stir well, cast into shape using a mold, and demold after standing for 24 hours.

[0061] (2) Mineralization of solidified waste incineration fly ash body: The solidified waste incineration fly ash body after demoulding is placed in an autoclave for CO2 mineralization reaction. Mineralization reaction conditions: 60°C, mineralization pressure: 0.8MPa, mineralization time: 24h, mineralization gas: 100% CO2. After the mineralization reaction is completed, the solidified waste incineration fly ash body is taken out and cooled.

[0062] Testing of solidified waste incineration fly ash: The solidified waste incineration fly ash obtained in Examples 1-7 and Comparative Examples 1-7 and untreated waste incineration fly ash were subjected to heavy metal leaching experiments using the "Solid Waste Leaching Toxicity Leaching Method - Acetate Buffer Solution Method" (HJ / T300-2007). Then, the content of heavy metal ions (Pb, Ni, Cr, Cd, As) in the leaching solution was detected using an inductively coupled plasma emission spectrometer. The carbon fixation rate of the solidified waste incineration obtained in Examples 1-7 and Comparative Examples 1-7 was tested using a thermogravimetric analysis system. The test results are shown in Table 1.

[0063] Table 1. Heavy metal leaching test results and carbon fixation rate

[0064]

[0065] It can be seen from Table 1 above that the leaching concentrations of heavy metals Pb, Ni, Cr, Cd and As in the waste incineration fly ash all exceed the maximum concentration values ​​set by the "Pollution Control Standards for Municipal Waste Landfills" (GB16889-2008) (Pb-0.25mg / L; Ni-0.5mg / L; Cr-4.5mg / L; Cd-0.15mg / L; As-0.3mg / L), and cannot be directly landfilled. To this end, under the premise of improving the fly ash treatment efficiency as much as possible, the present invention finds that when the fly ash content is 50wt.%-60wt.%, the cement content is 40wt.%-50wt.%, the water / ash ratio is 0.3-0.45, and the appropriate mineralization reaction conditions (mineral pressure: 1.2MPa-1.6MPa; mineralization temperature 40℃-100℃; mineralization time: 4h-12h), the leaching toxicity of heavy metals Pb, Ni, Cr, Cd, and As in the solidified body is lower than the maximum concentration value set by the "Landfill Pollution Control Standard for Domestic Waste" (GB16889-2008), which fully meets the landfill requirements of the landfill, and the carbon fixation rate of the corresponding solidified body is greater than 12.5%, showing good capture and carbon fixation performance. The implementation of the present invention can realize the harmless disposal of waste incineration fly ash, and at the same time realize the capture, solidification and storage of greenhouse gas CO2, which has very obvious environmental benefits.

[0066] It should be noted that the above specific implementations are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art should understand that various modifications, equivalent substitutions, changes, etc. can be made to the present invention. However, as long as these changes do not deviate from the spirit of the present invention, they should be within the scope of protection of the present invention. In addition, some terms used in the specification and claims of this application are not restrictive, but are only for the convenience of description.

Claims

1. A method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification, characterized in that: include: Preparation of fly ash solidified green body: using waste incineration fly ash and cement as raw materials, adding water, stirring evenly and then pouring into shape, and demoulding after standing to obtain fly ash solidified green body; Mineralization: The fly ash solidified body is placed in an autoclave and subjected to mineralization reaction using pure CO2 to obtain a solidified body of waste incineration fly ash; Among them, the added amount of waste incineration fly ash is 50wt.%-60wt.%, the added amount of cement is 40wt.%-50wt.%, the total added amount of waste incineration fly ash and cement is 100wt.%, and the water-cement mass ratio is 0.3-0.

45.

2. The method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification according to claim 1, characterized in that: The standing time is 18h-24h.

3. The method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification according to claim 1, characterized in that: The temperature of the mineralization reaction is 40°C-100°C.

4. The method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification according to claim 3, characterized in that: The pressure of the mineralization reaction is 1.2MPa-1.6MPa.

5. The method for mineralization and carbon fixation of waste incineration fly ash coupled with heavy metal solidification according to claim 3, characterized in that: The mineralization reaction time is 4h-10h.

6. A solidified body of fly ash from garbage incineration, characterized in that: The method is prepared by the method for mineralization and carbon fixation coupled with heavy metal solidification of waste incineration fly ash as described in any one of claims 1 to 5.

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