1. A method for solidifying fly ash generated by burning garbage is characterized by comprising the following steps:

s1, mixing the fly ash, the ground phosphate rock and the hydrolysate of the silane coupling agent containing the epoxy group, standing for reaction, and drying to obtain a fly ash premix;

s2, mixing the fly ash premix with a gelatin water solution, heating, stirring, reacting, and drying to obtain a fly ash mixture;

and S3, mixing the fly ash mixture with cement, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

2. The method for solidifying fly ash generated by power generation through waste incineration according to claim 1, wherein the weight ratio of the fly ash to the ground phosphate rock is 1: (0.15-0.25), wherein the weight ratio of the fly ash to the silane coupling agent KH-560 is 1: (0.01-0.02).

3. The method for solidifying fly ash generated by power generation through waste incineration according to claim 1 or 2, wherein in the step S1, the standing reaction time is 1-2h, and the drying temperature is 60-80 ℃.

4. The method for solidifying fly ash generated by power generation through incineration of waste according to any one of claims 1 to 3, wherein the hydrolysate of the silane coupling agent containing epoxy groups is prepared from the silane coupling agent containing epoxy groups, ethanol and water in a weight ratio of 1: (8-12): (3-6) the preparation method comprises the following steps: weighing the silane coupling agent containing the epoxy group, ethanol and water according to the weight ratio, mixing, uniformly stirring, and standing for 1-2h to obtain the epoxy silane coupling agent.

5. The method for solidifying fly ash generated by power generation through incineration of waste according to any one of claims 1 to 4, wherein the silane coupling agent containing an epoxy group is silane coupling agent KH-560.

6. The fly ash solidification method for waste incineration power generation according to any one of claims 1 to 5, wherein the weight of the gelatin is 1 to 2% of the weight of the fly ash, and the concentration of the aqueous solution of the gelatin is 10 to 30 g/L.

7. The method for solidifying fly ash generated by power generation through incineration of waste according to any one of claims 1 to 6, wherein in the step S2, the temperature of the heating and stirring reaction is 60 to 80 ℃, the time is 2 to 4 hours, and the temperature of the drying is 60 to 80 ℃.

8. The method for solidifying fly ash generated by power generation through waste incineration according to any one of claims 1 to 7, wherein in the step S3, the weight ratio of the fly ash mixture to the cement is 3:7-6: 4.

Background

With the acceleration of the urbanization process, the treatment of a large amount of domestic garbage generated in urban life becomes an important subject. The garbage incineration power generation is a technology of generating power by incinerating solid garbage and then using a steam unit, so that the municipal solid garbage can be treated, the energy in the garbage can be recovered, and the garbage incineration power generation is widely applied. However, the waste incineration power generation generates a large amount of fly ash, which contains heavy metal pollutants such as Pb and Cr, and these heavy metals are often attached to the fly ash in a soluble form, which poses a serious threat to the environment. Therefore, it is necessary to perform landfill treatment after the incineration fly ash is solidified.

The cement solidification is a method for mixing fly ash and cement according to a certain proportion and then forming a solidified body through hydration reaction, and the cement gelation solidification is used for reducing the permeability of heavy metal pollutants in the fly ash, thereby reducing the leaching toxicity of the fly ash and enabling the fly ash to meet the landfill requirement. However, in order to enable the solidified body to maintain higher strength and long-term stability, the cement mixing amount required by cement solidification is very high, so that the volume increment of the solidified body formed after solidification treatment is large, and the demand on the capacity of a landfill site is increased; in addition, the fly ash in the solidified body still releases impurity components to participate in the reaction after the solidified body is formed, so that the solidified body is corroded, and the stability of the solidified body is poor, so that the long-term solidification stability of the solidified body is not high.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a method for solidifying fly ash generated by burning garbage.

The invention provides a method for solidifying fly ash generated by burning garbage, which comprises the following steps:

s1, mixing the fly ash, the ground phosphate rock and the hydrolysate of the silane coupling agent containing the epoxy group, standing for reaction, and drying to obtain a fly ash premix;

s2, mixing the fly ash premix with a gelatin water solution, heating, stirring, reacting, and drying to obtain a fly ash mixture;

and S3, mixing the fly ash mixture with cement, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Preferably, the weight ratio of the fly ash to the ground phosphate rock is 1: (0.15-0.25), wherein the weight ratio of the fly ash to the silane coupling agent KH-560 is 1: (0.01-0.02).

Preferably, in the step S1, the standing reaction time is 1-2h, and the drying temperature is 60-80 ℃.

Preferably, the hydrolysate of the epoxy group-containing silane coupling agent is prepared from the epoxy group-containing silane coupling agent, ethanol and water in a weight ratio of 1: (8-12): (3-6) the preparation method comprises the following steps: weighing the silane coupling agent containing the epoxy group, ethanol and water according to the weight ratio, mixing, uniformly stirring, and standing for 1-2h to obtain the epoxy silane coupling agent.

Preferably, the silane coupling agent containing the epoxy group is a silane coupling agent KH-560.

Preferably, the weight of the gelatin is 1-2% of the weight of the fly ash, and the concentration of the aqueous solution of the gelatin is 10-30 g/L.

Preferably, in the step S2, the temperature for heating, stirring and reacting is 60-80 ℃, the time is 2-4h, and the temperature for drying is 60-80 ℃.

Preferably, in the step S3, the weight ratio of the fly ash mixture to the cement is 3:7-6: 4.

The invention has the following beneficial effects:

the invention obtains the fly ash premix by doping a proper amount of phosphate rock powder into the fly ash, modifies the fly ash premix by adopting the silane coupling agent containing the epoxy group, introduces the epoxy group on the surface of the fly ash premix, and then mixes and heats the fly ash premix with the aqueous solution of gelatin to react, so that the amino group of the gelatin reacts with the epoxy group combined on the surface of the fly ash premix to form a surface coating layer, thereby changing the surface property of the fly ash, on one hand, the gelatin is firmly combined on the surface of the fly ash, can play a bridging role between the fly ash and cement, improves the binding force between the fly ash and the cement, and is beneficial to improving the compressive strength of a solidified body, on the other hand, because the composition of the fly ash is extremely complex, the fly ash not only contains a large amount of heavy metal impurities, but also contains a large amount of fine insoluble, the strength of a solidified body is reduced, and insoluble particle impurities are different from the surface properties of fly ash and can hinder the combination of the fly ash and cement; moreover, the addition of the ground phosphate rock can also play an auxiliary role in improving the internal pore structure of the solidified body, so that the strength of the solidified body is further improved; meanwhile, the phosphate rock powder can effectively combine with heavy metal ions in the fly ash to reduce leaching of the fly ash, the gelatin coating further prevents the heavy metal ions in the fly ash from migrating, and the formed coating layer can also prevent the erosion effect of impurities in the fly ash on cement, so that the curing stability of the solidified body on the heavy metal ions can be obviously improved.

The curing method can improve the compressive strength of the fly ash cement cured body, reduce the leachability of heavy metal impurities in the cured body, ensure that the obtained cured body can meet the requirement that the compressive strength is more than or equal to 10MPa under the condition of high fly ash content, meet the standard limit of GB5085.3-2007 hazardous waste leaching toxicity standard, can meet the requirement of being used as a building material, is favorable for realizing the high-efficiency, energy-saving and economic recycling of the fly ash generated by burning garbage, and meets the actual use requirement.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

A method for solidifying fly ash generated by burning garbage comprises the following steps:

s1, mixing the fly ash, the ground phosphate rock and the hydrolysate of the silane coupling agent containing the epoxy group, standing for reaction, and drying to obtain a fly ash premix;

s2, mixing the fly ash premix with a gelatin water solution, heating, stirring, reacting, and drying to obtain a fly ash mixture;

and S3, mixing the fly ash mixture with cement, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Example 2

A method for solidifying fly ash generated by burning garbage comprises the following steps:

s1, mixing 0.1kg of silane coupling agent KH-560, 0.8kg of ethanol and 0.3kg of water, uniformly stirring, standing for 1h to obtain hydrolysate of the silane coupling agent KH-560, mixing 10kg of fly ash and 1.5kg of ground phosphate rock with the prepared hydrolysate of the silane coupling agent KH-560, standing for reaction for 1h, and drying at 60 ℃ to obtain a fly ash premix;

s2, dissolving 0.1kg of gelatin in water to obtain a gelatin aqueous solution with the concentration of 10g/L, mixing the fly ash premix with the prepared gelatin aqueous solution, heating and stirring at 60 ℃ for reaction for 4 hours, and drying at 60 ℃ to obtain a fly ash mixture;

s3, mixing the fly ash mixture and cement according to the weight ratio of 3:7, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Example 3

A method for solidifying fly ash generated by burning garbage comprises the following steps:

s1, mixing 0.2kg of silane coupling agent KH-560, 2.4kg of ethanol and 1.2kg of water, uniformly stirring, standing for 2 hours to obtain hydrolysate of the silane coupling agent KH-560, mixing 10kg of fly ash and 2.5kg of ground phosphate rock with the prepared hydrolysate of the silane coupling agent KH-560, standing for reaction for 2 hours, and drying at 80 ℃ to obtain a fly ash premix;

s2, dissolving 0.2kg of gelatin in water to obtain a gelatin water solution with the concentration of 20g/L, mixing the fly ash premix with the prepared gelatin water solution, heating and stirring at 80 ℃ for reaction for 2 hours, and drying at 80 ℃ to obtain a fly ash mixture;

s3, mixing the fly ash mixture and cement according to the weight ratio of 6:4, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Example 4

A method for solidifying fly ash generated by burning garbage comprises the following steps:

s1, mixing 0.15kg of silane coupling agent KH-560, 1.5kg of ethanol and 0.75kg of water, uniformly stirring, standing for 1.5h to obtain hydrolysate of the silane coupling agent KH-560, mixing 10kg of fly ash and 2kg of ground phosphate rock with the prepared hydrolysate of the silane coupling agent KH-560, standing for reaction for 1.5h, and drying at 75 ℃ to obtain fly ash premix;

s2, dissolving 0.15kg of gelatin in water to obtain a gelatin water solution with the concentration of 30g/L, mixing the fly ash premix and the prepared gelatin water solution, heating and stirring at 65 ℃ for reaction for 3 hours, and drying at 75 ℃ to obtain a fly ash mixture;

s3, mixing the fly ash mixture and cement according to the weight ratio of 5:5, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Comparative example 1

A method for solidifying fly ash generated by burning garbage comprises the following steps: mixing fly ash and cement in the weight ratio of 6:4, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Comparative example 2

A method for solidifying fly ash generated by burning garbage comprises the following steps: mixing the fly ash mixture and cement according to the weight ratio of 6:4, adding a proper amount of water, uniformly stirring, standing and maintaining in a mold to form a solidified body, wherein the fly ash mixture is formed by mixing 10kg of fly ash and 2.5kg of phosphate rock powder.

Comparative example 3

A method for solidifying fly ash generated by burning garbage comprises the following steps:

s1, uniformly mixing 10kg of fly ash and 2.5kg of phosphate rock powder to obtain fly ash premix;

s2, dissolving 0.2kg of gelatin in water to obtain a gelatin water solution with the concentration of 20g/L, mixing the fly ash premix with the prepared gelatin water solution, heating and stirring at 80 ℃ for reaction for 2 hours, and drying at 80 ℃ to obtain a fly ash mixture;

s3, mixing the fly ash mixture and cement according to the weight ratio of 6:4, adding a proper amount of water, uniformly stirring, and standing and curing in a mold to form a solidified body.

Test examples

The compression strength of the solidified bodies after static curing for 28d in example 3 and comparative examples 1-3 was tested by a cement strength tester according to GB/T17671-1999 standard, and the test results are shown in Table 1:

TABLE 1 compressive Strength test results

As can be seen from Table 1, the curing method of the present invention can significantly improve the compressive strength of the cured body, because the present invention modifies fly ash by the silane coupling agent KH-560 containing epoxy groups, and then the amino group of gelatin reacts with the epoxy groups bonded on the fly ash surface, so that the gelatin is firmly bonded on the fly ash surface to form a surface coating layer, and the coating modification of gelatin changes the surface property of fly ash, improves the cohesiveness and plasticity of fly ash, and can also avoid the direct contact between the impurities in fly ash and cement to cause the reduction of mechanical properties, and the incorporation of phosphate rock powder can play an auxiliary role in improving the internal pore structure of the cured body. The solidified body obtained by the solidification method can meet the standard requirement that the compressive strength is more than or equal to 10MPa under the condition of high fly ash content, can meet the requirement of being used as a building material, and meets the actual use requirement.

After the solidified bodies obtained in example 3 and comparative examples 1 to 3 after being left to stand and cured for 28d were crushed, leaching tests were carried out in accordance with GB5086.2-1997 standard to test the concentrations of Pb, Cu and Cr; the results of the leaching test are shown in table 2:

table 2 results of leaching test

Test items	Example 3	Comparative example 1	Comparative example 2	Comparative example 3
					Pb concentration (mg/L)	0.021	0.066	0.035	0.029
Cu concentration (mg/L)	0.013	0.049	0.026	0.021
					Cr concentration (mg/L)	0.087	0.630	0.283	0.233

As can be seen from Table 2, the curing method of the present invention can effectively reduce the leachability of heavy metal ions in the fly ash, since the powdered rock phosphate can effectively combine with the heavy metal ions in the fly ash to reduce the leaching, and the gelatin coating further prevents the migration of the heavy metal ions in the fly ash.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.