CN113413570B

CN113413570B - Preparation and application of long-period stable fly ash chelating agent

Info

Publication number: CN113413570B
Application number: CN202011472627.9A
Authority: CN
Inventors: 杨公华; 周小峰; 蔡振山; 陈煜辉; 敖浚轩; 边超; 袁久婷
Original assignee: Shenzhen Changlong Technology Co ltd
Current assignee: Shenzhen Changlong Technology Co ltd
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2022-07-22
Anticipated expiration: 2040-12-15
Also published as: CN113413570A

Abstract

The invention relates to a method for solving heavy metals or other harmful substances (alkyl mercury, inorganic fluoride and cyanide) in fly ash generated by burning household garbage or dangerous waste in the field of solid waste disposal. The invention mainly adopts polycarboxylic acid as a chelating agent to stabilize heavy metals in fly ash. The water reducing property of the polycarboxylic acid can increase the contact between interfaces, increase the contact chance of the chelating agent and various heavy metals in the fly ash, and simultaneously, the universality of the chelating of various heavy metals is improved by adding the lignosulfonate or naphthalene sulfonate formaldehyde condensate. A large number of carboxyl groups in the polycarboxylic acid and lone-pair electrons on oxygen in the polyether chain can be subjected to chelation reaction with heavy metals under an acidic condition, and the chelate is insoluble in water, so that the heavy metals can be stabilized under a long-period storage condition. The chelate-cured ash can be subjected to landfill treatment, and the addition of the polycarboxylic acid can also improve the collapse-keeping performance. In addition, the polycarboxylic acid is environment-friendly and does not cause secondary pollution.

Description

Preparation and application of long-period stable fly ash chelating agent

Technical Field

The invention belongs to the field of solid waste disposal, and particularly relates to a preparation method of a fly ash chelating agent for stabilizing heavy metals and other harmful substances (alkyl mercury, inorganic fluoride and cyanide) in fly ash generated by burning household garbage and hazardous waste.

Technical Field

Solid refuse incineratorDue to the advantages of reduction, harmlessness and recycling, the burning is gradually the main treatment method for harmlessness of domestic solid waste garbage. The daily treatment capacity of solid waste incineration is 6.247 multiplied by 10 by 2018⁵t, annual incineration amount is 2.28X 10⁸t, the incineration fly ash which is 2 to 5 percent of the original garbage mass can be generated after the garbage is incinerated. However, secondary pollution is generated in the process of burning garbage, wherein the fly ash is rich in heavy metals and dioxin, and the fly ash from burning household garbage is defined as hazardous waste (HW18) in the technical policy of hazardous waste pollution control issued in 2001 of China. The household garbage incineration fly ash can be transported for safe landfill disposal after necessary solidification and stabilization treatment in a production place, which means that the incineration fly ash can be transported into a household garbage landfill for disposal after the standard disposal reaches the national standard of pollution control standard of household garbage landfill (GB 16889-2008). In addition, fly ash generated from the incinerated hazardous waste is disposed in landfills in accordance with "hazardous waste landfill pollution control Standard" (GB 18598-2019).

The treatment method of fly ash generated by incineration mainly includes cement solidification, medicament stabilization, fusion heat treatment, heavy metal extraction and other methods. Among them, cement solidification is gradually eliminated due to the increase of compatibilization cost caused by a large addition amount, and the cost of melt heat treatment is high and secondary pollution is caused. The medicament stabilization technology is the mainstream technology due to the advantages of low capacity increase, low cost, high heavy metal stabilization efficiency, strong acid leaching resistance and the like. However, currently, the fly ash stabilizers commonly used can be classified into inorganic agents and organic agents. The waste treated by the inorganic chelating agent stabilization treatment technology has large capacity increase, and the heavy metals in the fly ash can be leached secondarily by referring to the leaching method of HJ 300 and HJ 299, so that the long-term safety requirement of hazardous waste treatment is difficult to meet. Therefore, organic agents have become hot spots for fly ash stabilization treatment. However, the dithioates, piperazines and trimercaptotriazine trisodium adopted by the prior fly ash chelating agents have the problems of large odor, easy decomposition of the chelate, poor universality, insufficient chelating reaction caused by liquid-solid heterogeneous phase and the like.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method and application of a waste incineration fly ash chelating agent which is low in smell, long in stable period, high in universality and sufficient in chelating reaction.

The invention provides a preparation method and application of a waste incineration fly ash chelating agent, which is characterized by comprising the following steps:

(1) the fly ash chelating agent is an aqueous solution of a high molecular polymer, and the high molecular polymer mainly comprises polycarboxylic acid. In addition, one or more of lignosulfonate or naphthalene sulfonate formaldehyde condensate is added for compounding;

(2) the polycarboxylic acid in the step (1) takes acrylic acid or methacrylic acid as a main chain, and polyether with different side chain lengths is grafted. Wherein, the polymerization degree of acrylic acid or methacrylic acid is 100-1000, the side chain polyether is polyethylene glycol terminated by monomethoxy, and the polymerization degree of the polyether is 1-100, preferably 10-50.

(3) The mass ratio of the polycarboxylic acid to one or more of lignosulfonate or naphthalene sulfonate formaldehyde condensate in the step (1) is 100: (0-10), preferably 100: (0-5), and then dissolving the compound in water to obtain the product.

(4) The mass ratio of the polymer to the water in the step (3) is 100: (1-60), preferably 100: (20-40). And according to the proportion, uniformly dissolving the polymer in water to obtain the fly ash chelating agent.

(5) Firstly, diluting the fly ash chelating agent prepared in the step (4) into water, and then adding the diluted fly ash chelating agent into fly ash generated by burning to be mechanically and uniformly mixed to generate a chelating and curing reaction. Standing the chelated and solidified fly ash for 24 hours, and then carrying out extraction experiments according to the extraction method of HJ 299 or HJ 300. And finally, judging whether the standard meets the landfill standard according to the landfill standard in GB16889 or GB 18598.

(6) The fly ash in the step (5): a fly ash chelating agent: the mass ratio of water is 100: (1-10): (1-40), and the optimized mass ratio is 100: (3-5): (5-20).

The invention is based on the following principle: the invention relates to a method for solving heavy metals or other harmful substances (dioxin, alkyl mercury, inorganic fluoride and cyanide) in fly ash generated by burning household garbage or dangerous waste in the field of solid waste disposal. The invention mainly adopts polycarboxylic acid as a chelating agent to stabilize heavy metals in fly ash, and the polycarboxylic acid is taken as the chelating agent mainly considering that the polycarboxylic acid has the following characteristics: (1) the fly ash chelating agent and the fly ash generated by incineration have a chelating reaction which is a heterogeneous reaction generated on a liquid-solid interface, the contact between the interfaces can be increased by adding the polycarboxylic acid, the contact opportunity of various heavy metals in the chelating agent and the fly ash is increased, and the universality for the heavy metals is high. (2) The polycarboxylic acid is dissolved in water to show acidity, a large amount of carboxyl and lone pair electrons in oxygen in a polyether chain can be insoluble in water after undergoing a chelation reaction with heavy metals under an acidic condition, and then can be kept stable in the process of leaching through HJ 299 or HJ 300, so that the heavy metals can be stabilized for a long period. (3) The ash after chelating and curing can be subjected to landfill treatment, and the collapse-keeping performance can be improved by adding the polycarboxylic acid. Because the polycarboxylic acid has no odor, the fly ash added into the chelate curing landfill can not cause air pollution. (4) The addition of a small amount of lignosulfonate or naphthalene sulfonate formaldehyde condensate is mainly based on the stabilization of the sulfonic acid group of the condensate to heavy metals.

Compared with the prior art, the invention has the following advantages and effects: the fly ash produced by burning solid waste by adopting the chelating agent mainly comprising polycarboxylic acid has the following advantages: (1) the polycarboxylic acid is taken as the main component, and the polycarboxylic acid and the lignosulfonate or naphthalene sulfonate formaldehyde condensate are compounded for use, so that the chelating and curing reaction can be performed on heavy metals in GB16889 and GB18598, and the universality is very strong. (2) The chelate group of the polycarboxylic acid is more, the chelate after the chelation reaction is insoluble in water and acid-resistant, and the chelate can be stable for a long period without leaching under the acidic condition. (3) The polycarboxylic acid is green and environment-friendly, and does not cause secondary pollution.

Drawings

FIG. 1 is a graph showing a summary of results of comparative experiment # 1 and chelate curing experiments # 1 to # 4, FIG. 2 is a graph showing a summary of results of comparative experiment # 1 and chelate curing experiments # 5 to # 7, and FIG. 3 is a graph showing a summary of results of comparative experiment # 2 and chelate curing experiments # 8 to # 10.

Detailed Description

The following description will be made in detail with reference to specific examples to stabilize heavy metals in fly ash generated by burning solid waste with a polycarboxylic acid-based fly ash chelating agent according to the present invention.

The fly ash generated by burning the solid waste is the fly ash 1# generated by a certain household garbage burning power plant in Hei Zhou, Guangdong, and the fly ash generated by burning the dangerous waste is the fly ash 2# generated by a certain dangerous waste disposal unit in Zhanjiang, Guangdong. Polycarboxylic acids, lignosulfonates and naphthalene sulfonates are all produced by one manufacturer.

And (3) a fly ash chelation process:

(1) 10g of fly ash is weighed into a clean plastic cup, dried in an oven at 105 ℃ for 4h, and tested for water content.

(2) Respectively weighing fly ash in a clean plastic measuring cup, uniformly mixing different chelating agents and water, pouring the mixture into the fly ash for 3 times, stirring while adding until the chelating agents are fully contacted with the fly ash, stirring the completely chelated fly ash to form wet solid yellowish brown particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

(3) 15g of the chelated samples were taken respectively and dried in an oven at 105 ℃ for 4h until dried yellowish brown powder particles were obtained, and the solid content was measured respectively.

2. Leaching the fly ash chelate:

leaching method # 1: 17.25ml of glacial acetic acid and ultrapure water are transferred into a volumetric flask by a pipette, the volume is constant to 1L, and the pH value is measured to be about 2.6. Adding the leaching liquor according to the solid content and the liquid-solid ratio of 20:1, placing the leaching liquor into a turnover instrument, turning the turnover instrument for 18h for leaching, wherein gas needs to be released twice in the first 4 hours, and 75g of solid is generally taken. And taking the sample from the turnover instrument, filtering 150ml of leaching liquor in a plastic bottle by using full glass and a 6 mu m microporous filter membrane filter sand core filtering device under reduced pressure respectively, and detecting the concentration of various heavy metal ions. (HJ 300)

Leaching method # 2: firstly, mixing the components in a mass ratio of 2: 1 of concentrated sulfuric acid and concentrated nitric acid was added to reagent water (1L of a mixture of about 2 drops of water) to adjust the pH to 3.20. + -. 0.05. Adding the leaching liquor according to the solid content and the liquid-solid ratio of 10:1, placing the leaching liquor into a turnover instrument, turning the turnover instrument for 18 hours for leaching, and deflating twice in the first 4 hours. Taking down the sample from the turnover instrument, respectively filtering 150ml of leaching liquor in a plastic bottle by using all-glass and 6 mu m microporous filter membrane filter sand core filtering devices under reduced pressure, and detecting the concentration of various heavy metal ions. (HJ 299)

2.2 results of the experiment

Heavy metal detection

The fly ash after chelation is detected by using an HJ 300-2007-plus-2007 leaching method, the leaching concentration of the heavy metal of the fly ash from the incineration of the household garbage, which is extracted after the treatment, reaches the national pollution control Standard for landfill of household garbage GB16889-2008, and enterprises particularly have to refer to the local emission standard.

The chelated fly ash is detected by using an HJ 299-2007 leaching method, the heavy metal extracted after treatment reaches the national hazardous waste landfill pollution control Standard GB18598-2019, and enterprises specifically refer to the local emission standard.

Comparative experiment No. 1#

Weighing 75g of fly ash No. 1 in a clean plastic measuring cup respectively, testing the water content, and directly carrying out extraction experiments by using an extracting agent No. 1 without adding any chelating agent.

Example 1

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup respectively, uniformly mixing 3g of polycarboxylic acid and 30g of water, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to be wet solid granules in the shape of khaki, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 2

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup respectively, uniformly mixing 3g of polycarboxylic acid and 15g of water, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to be wet solid yellowish brown particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 3

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup respectively, uniformly mixing 5g of polycarboxylic acid and 15g of water, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to be wet solid yellowish brown particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 4

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup respectively, uniformly mixing 10g of polycarboxylic acid and 15g of water, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to be wet solid yellowish brown particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 5

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup respectively, uniformly mixing 3g of polycarboxylic acid, 0.5g of lignosulfonate and 15g of water, pouring into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring completely chelated fly ash to form moist solid yellowish brown particles, and placing the stirred chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 6

Weighing 100g of fly ash No. 1 in a clean plastic measuring cup, uniformly mixing 3g of polycarboxylic acid, 0.5g of naphthalene sulfonate and 15g of water, pouring into the fly ash by 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to form wet solid yellowish brown particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 7

Respectively weighing 100g of fly ash No. 1 into a clean plastic measuring cup, uniformly mixing 3g of polycarboxylic acid, 0.05g of naphthalene sulfonate, 0.10g of lignosulfonate and 15g of water, pouring into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring completely chelated fly ash to form moist yellowish brown solid particles, and placing the stirred chelated fly ash into a ventilation cabinet for chelation and aging for 24 hours.

Comparative experiment No. 2#

Respectively weighing 75g of fly ash No. 2 into a clean plastic measuring cup, testing the water content, and directly adopting an extracting agent No. 2 to carry out an extracting experiment without adding any chelating agent.

Example 8

Respectively weighing 100g of fly ash No. 2 in a clean plastic measuring cup, uniformly mixing 3g of polycarboxylic acid and 30g of water, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to form moist solid yellowish brown solid particles, and placing the stirred and chelated fly ash in a fume hood for chelation and aging for 24 hours.

Example 9

Weighing 100g of fly ash No. 2 in a clean plastic measuring cup respectively, uniformly mixing 15g of water in 3g of polycarboxylic acid, pouring the mixture into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, wherein the fly ash after complete chelation by stirring is moist solid granules with soil color, and placing the fly ash after complete chelation by stirring in a fume hood for chelation and aging for 24 hours.

Example 10

Weighing 100g of fly ash No. 2 in a clean plastic measuring cup, uniformly mixing 3g of polycarboxylic acid, 0.05g of naphthalene sulfonate, 0.10g of lignosulfonate and 15g of water, pouring into the fly ash for 3 times, stirring while adding until a chelating agent is fully contacted with the fly ash, stirring the completely chelated fly ash to form wet earthy yellow solid particles, and placing the stirred and chelated fly ash in a fume hood for chelating and aging for 24 hours.

The results of the heavy metals and other indicators for examples 1-10# and comparative examples 1-2# above are summarized in the next figure

According to the experimental results in the first, second and third graphs, the fly ash generated by burning the household garbage and the fly ash generated by hazardous wastes have the risk of exceeding the standard of heavy metals such as Zn, Pb, Cd and the like. As can be seen from the data of examples 2# and 9#, the addition of 3% polycarboxylic acid can largely stabilize Zn and Pb, but Cd still has the risk of exceeding the standard. The lignosulfonate and the naphthalene sulfonate both have obvious effect on Cd, and the compound use effect of the lignosulfonate and the naphthalene sulfonate is better from the data of the example 7# and the example 10 #.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made in the formulation and preparation process of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The preparation method of the waste incineration fly ash chelating agent is characterized by comprising the following steps: the fly ash chelating agent is an aqueous solution of a high molecular polymer, wherein the high molecular polymer mainly comprises polycarboxylic acid; in addition, lignosulfonate and naphthalene sulfonate formaldehyde condensate are added as auxiliary agents; the naphthalene sulfonate formaldehyde condensate and the lignosulfonate were used in amounts of 0.05g and 0.1g, respectively, based on 3g of polycarboxylic acid.

2. The method according to claim 1, wherein the polycarboxylic acid comprises acrylic acid or methacrylic acid as a main chain, and polyethers having different side chain lengths are grafted; wherein, the polymerization degree of the acrylic acid or the methacrylic acid is 100-1000, the side chain polyether is polyethylene glycol terminated by monomethoxy, and the polymerization degree of the polyether is 1-100.

3. The method according to claim 2, wherein the mass ratio of the polymer to water is 100: (1-60); and uniformly dissolving the polymer in water according to the proportion to obtain the fly ash chelating agent.

4. The method of claim 3, wherein the fly ash chelating agent is diluted in water, and then the diluted fly ash chelating agent is added to the fly ash generated by burning, and the mixture is mechanically mixed to generate chelating and solidifying reaction.

5. A method of using a fly ash sequestrant according to claim 4, characterized in that the fly ash: a fly ash chelating agent: the mass ratio of water is 100: (1-10): (1-40).

6. A method for using a fly ash chelating agent according to claim 5, wherein the ash is fly ash generated by burning domestic garbage or hazardous waste, and the fly ash after chelating and solidifying is left to stand for 24h and then leaching experiments are carried out according to the leaching method of HJ 299 or HJ 300; finally, whether the standard meets the landfill standard is judged according to the landfill standard in GB16889 or GB 18598.