Waste incineration fly ash purification method

Abstract

The invention relates to the technical field of hazardous waste resource utilization, in particular to a waste incineration fly ash purification method. The invention provides a waste incineration fly ash purification method which comprises the following steps: mixing fly ash with sulfuric acid, an organic extraction agent, sodium phosphate dodecahydrate and sodium sulfide for reaction, and reacting ions with sulfuric acid, the organic extraction agent, sodium phosphate dodecahydrate and sodium sulfide, and harmful ions are converted into soluble salts and then are washed, so that the concentration of the harmful ions in the fly ash is effectively reduced. The method is simple and easy to implement, low in cost and remarkable in purification effect, and the removal rates of the heavy metals Zn, Pb, Cu, Ba and Cl reach 97.75%, 61.36%, 90.3%, 98.11% and 94.37% respectively. The obtained fly ash has high building material activity and can be used for production of various building material products.

Description

Technical Field

[0001] The present application relates to the technical field of hazardous waste resource utilization, and specifically to a method for purifying fly ash from waste incineration. Background Art

[0002] Waste incineration fly ash is the bottom ash that settles at the bottom of the flue and chimney when the high-temperature flue gas passes through the flue gas purification system during the incineration of domestic waste. Fly ash contains a large amount of heavy metals such as Cr, Cd, Hg, etc., as well as organic pollutants such as dioxins, which are extremely harmful to human health and the environment. The heavy metals and dioxins in fly ash have high leaching toxicity. If they are directly discharged or landfilled without treatment, they will cause serious pollution to the soil, water and atmosphere. Therefore, they need to be harmlessly treated.

[0003] At present, the main method of fly ash disposal is landfill after solidification and stabilization, but this method has many problems. Landfill cannot completely solve the pollution problem of fly ash and occupies a large amount of land resources. In addition, as the capacity of landfills approaches saturation, landfill disposal is not in line with the environmental concept of sustainable development. Although cement kiln co-disposal is widely used, it is limited by the production capacity of building materials, and as the demand for cement decreases, the amount of fly ash that can be co-disposed is limited.

[0005] Therefore, the current key research direction is to find a fly ash purification method that can effectively treat harmful substances in fly ash and produce a product with high building material activity that can be used in the production of a variety of building materials. Summary of the invention

[0006] In order to solve the above technical problems existing in the prior art, the present application provides a method for purifying fly ash from waste incineration, which is as follows:

[0007] A method for purifying fly ash from garbage incineration comprises the following steps:

[0008] S1. Take fly ash and acid, mix and stir uniformly to react, wherein the acid is one or more of sulfuric acid, hydrochloric acid and nitric acid mixed in any proportion;

[0009] S2. When the reaction of S1 is completed and no residual heat is released, an organic extractant is added;

[0010] S3. Sodium phosphate dodecahydrate was added and the reaction was stirred evenly; subsequently, sodium sulfide was added, wherein sodium phosphate and sodium sulfide may also be heavy metal capture agents, etc., and the reaction was stirred evenly;

[0011] S4. After the reaction is completed, the mixed solution is vacuum filtered and the filter residue is vacuum dried to obtain a fly ash acid washing product;

[0012] S5. Add deionized water to the fly ash pickling product obtained in S4, stir at a uniform speed, vacuum filter the mixed solution, and de-wash; finally, vacuum dry the obtained sample to obtain harmless fly ash.

[0013] Furthermore, the acid is sulfuric acid. Preferably, the solid-liquid ratio of fly ash to sulfuric acid in S1 is 1:1-7, and the concentration of sulfuric acid is 8%-57%.

[0014] Furthermore, the organic extractant in S2 is any one of insoluble carboxylic acid, sulfonated kerosene, and organic phosphorus (phosphonic) acid.

[0015] Furthermore, the ratio of fly ash to organic extractant in S2 is 1:1-3.

[0016] Furthermore, the ratio of fly ash to sodium phosphate dodecahydrate in S3 is 1:1-3; the ratio of fly ash to sodium sulfide is 1:0.005-0.04.

[0017] Furthermore, the vacuum filtration is performed using a filter membrane with a pore size of 0.45 um.

[0018] Furthermore, the ratio of fly ash to deionized water in S5 is 1:3-7.

[0019] Furthermore, the elution in S5 is performed 2-6 times, preferably 3 times.

[0020] Compared with the prior art, the technical effects created by this application are embodied in:

[0021] The present application provides a method for purifying fly ash from garbage incineration, wherein fly ash is mixed with sulfuric acid, an organic extractant, sodium phosphate dodecahydrate and sodium sulfide for reaction, wherein the ions react with sulfuric acid, an organic extractant, sodium phosphate dodecahydrate and sodium sulfide, and the harmful ions are converted into soluble salts and then washed with water to effectively reduce the concentration of harmful ions in the fly ash. The method of the present application is simple and easy to implement, low in cost and has a significant purification effect, wherein the removal rates of heavy metals Zn, Pb, Cu, Ba and Cl reach 97.75%, 61.36%, 90.3%, 98.11% and 94.37% respectively. The obtained fly ash has a high activity for building materials and can be used for the production of a variety of building materials products. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a simplified process flow diagram of this application. DETAILED DESCRIPTION

[0023] The technical solution of the present application is further limited below in conjunction with specific implementation methods, but the scope of protection required is not limited to the description.

[0024] Example 1

[0025] ① Weigh 10g of fly ash into a beaker, add 70mL of 8% sulfuric acid and stir at a constant speed for 30min;

[0026] ② After step ① is cooled, add 15 mL of organic extractant (sulfonated kerosene) and react for 30 min;

[0027] ③After the reaction is finished, add 15g of sodium phosphate dodecahydrate and continue the reaction for 30 minutes;

[0028] ④ Add 0.32 mol of sodium sulfide, react for 30 minutes, then vacuum filter and dry;

[0029] ⑤After step ④ is completed, the filter cake is deionized and washed three times with deionized water, filtered and dried to obtain harmless fly ash, and the removal rates of heavy metals Zn, Pb, Cu, Ba and Cl reach 97.73%, 62.16%, 91.22%, 97.65% and 94.17%, respectively.

[0030] Example 2

[0031] ① Weigh 10g of fly ash into a beaker, add 70mL of 13% hydrochloric acid and stir at a constant speed for 30min;

[0032] ② After step ① is cooled, add 18 mL of organic extractant (organic phosphorus (phosphonic) acid) and react for 30 minutes;

[0033] ③After the reaction is finished, add 15g of sodium phosphate dodecahydrate and continue the reaction for 30 minutes;

[0034] ④ Add 0.32 mol of sodium sulfide, react for 30 minutes, then vacuum filter and dry;

[0035] ⑤After step ④ is completed, the filter cake is deionized and washed three times with deionized water, filtered and dried to obtain harmless fly ash, and the removal rates of heavy metals Zn, Pb, Cu, Ba and Cl reach 97.81%, 64.23%, 95.12%, 96.95% and 95.73%, respectively.

[0036] Example 3

[0037] ① Weigh 10g of fly ash into a beaker, add 70mL of 10% nitric acid and stir at a constant speed for 30min;

[0038] ② After step ① is cooled, add 14 mL of organic extractant (sulfonated kerosene) and react for 30 min;

[0039] ③After the reaction is finished, add 15g of sodium phosphate dodecahydrate and continue the reaction for 30 minutes;

[0040] ④ Add 0.32 mol of sodium sulfide, react for 30 minutes, then vacuum filter and dry;

[0041] ⑤After step ④ is completed, the filter cake is deionized and washed three times with deionized water, filtered and dried to obtain harmless fly ash, and the removal rates of heavy metals Zn, Pb, Cu, Ba and Cl reach 97.75%, 61.36%, 90.3%, 98.11% and 94.37%, respectively.

[0042] Example 4

[0043] ① Weigh 10g of fly ash into a beaker, add 70mL of 15% sulfuric acid and stir at a constant speed for 30min;

[0044] ② After step ① is cooled, add 20 mL of organic extractant (sulfonated kerosene) and react for 30 min;

[0045] ③After the reaction is completed, add 18g of sodium phosphate dodecahydrate and continue the reaction for 30 minutes;

[0046] ④ Add 0.28 mol of sodium sulfide, react for 30 minutes, then vacuum filter and dry;

[0047] ⑤After step ④ is completed, the filter cake is deionized and washed three times with deionized water, filtered and dried to obtain harmless fly ash, and the removal rates of heavy metals Zn, Pb, Cu, Ba and Cl reach 96.34%, 64.51%, 95.41%, 95.21% and 94.31%, respectively.

[0048] Finally, it should be pointed out that the above embodiments are only representative examples of the present application. Obviously, the technical solution of the present application is not limited to the above embodiments, and there may be many variations. All variations that can be directly derived or associated with the contents disclosed in the present application by a person of ordinary skill in the art should be considered as the protection scope of the present application.

Claims

1. A method for purifying fly ash from garbage incineration, characterized in that: The steps include: S1. Take fly ash and acid, mix and stir uniformly to react, wherein the acid is one or more of sulfuric acid, hydrochloric acid and nitric acid mixed in any proportion; S2. When the reaction of S1 is completed and no residual heat is released, an organic extractant is added; S3. Add sodium phosphate dodecahydrate and continue to stir the reaction evenly; then, add sodium sulfide and keep stirring the reaction at a uniform speed; S4. After the reaction is completed, the mixed solution is vacuum filtered and the filter residue is vacuum dried to obtain a fly ash acid washing product; S5. Add deionized water to the fly ash pickling product obtained in S4, stir at a uniform speed, vacuum filter the mixed solution, and de-wash; finally, vacuum dry the obtained sample to obtain harmless fly ash.

2. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The acid is sulfuric acid.

3. The method for purifying fly ash from waste incineration according to claim 2, characterized in that: The solid-liquid ratio of fly ash to sulfuric acid in the S1 is 1:1-7, and the concentration of sulfuric acid is 8%-57%.

4. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The organic extractant in S2 is any one of insoluble carboxylic acid, sulfonated kerosene, and organic phosphorus (phosphonic) acid.

5. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The ratio of fly ash to organic extractant in S2 is 1:1-3.

6. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The ratio of fly ash to sodium phosphate dodecahydrate in S3 is 1:1-3; the ratio of fly ash to sodium sulfide is 1:0.005-0.

04.

7. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The vacuum filtration uses a filter membrane with a pore size of 0.45 um for filtration.

8. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The ratio of fly ash to deionized water in S5 is 1:3-7.

9. The method for purifying fly ash from waste incineration according to claim 1, characterized in that: The elution in S5 is performed 2 to 6 times.

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