CN114602115B - Curing agent for heavy metals in household garbage incineration fly ash and fixing method applying curing agent - Google Patents
Curing agent for heavy metals in household garbage incineration fly ash and fixing method applying curing agent Download PDFInfo
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D3/00—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances
- A62D3/30—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents
- A62D3/33—Processes for making harmful chemical substances harmless or less harmful, by effecting a chemical change in the substances by reacting with chemical agents by chemical fixing the harmful substance, e.g. by chelation or complexation
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
- A62D2101/08—Toxic combustion residues, e.g. toxic substances contained in fly ash from waste incineration
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
- A62D2101/00—Harmful chemical substances made harmless, or less harmful, by effecting chemical change
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The application relates to the field of waste incineration, and particularly discloses a curing agent for heavy metals in household waste incineration fly ash and a fixing method applying the curing agent. The heavy metal curing agent in the household garbage incineration fly ash comprises the following substances in parts by weight: 20-30 parts of cement, 6-10 parts of metakaolin, 10-15 parts of slag, 5-9 parts of water, 5-10 parts of red mud and 10-15 parts of an additive, wherein the additive comprises a stabilizer which comprises sludge biochar and fishbone powder in a mass ratio of 5-9; a method for fixing heavy metals in household garbage incineration fly ash by using a curing agent comprises the following steps: s1, premixing treatment; s2, stabilizing; and S3, curing. The curing agent can be used for curing the fly ash generated by burning the household garbage, and has the advantages of stable curing effect and small compatibilization.
Description
Technical Field
The application relates to the field of waste incineration, in particular to a curing agent for heavy metals in household waste incineration fly ash and a fixing method applying the curing agent.
Background
The household garbage incineration is a process of carrying out high-temperature oxidation volume reduction on the household garbage through appropriate reactions such as thermal decomposition, combustion, melting and the like to form residues or molten solids. The household garbage incineration process is necessarily provided with the smoke treatment equipment, smoke generated by household garbage incineration is treated through the smoke treatment equipment, and the possibility that the smoke is dissipated into the air to pollute the environment and the air is reduced.
In the process of burning the household garbage, organic matters are usually discharged in a gas form, inorganic matters form solid particles, large particles of the particles are deposited at the bottom of the incinerator to form bottom ash, and fine particles are discharged along with organic matter gas to form incineration fly ash. The incineration fly ash also comprises limestone or activated carbon granules added in the flue gas purification process. In the process of burning the household garbage, a large amount of heavy metal aerosol series small particles are generated, and the burning fly ash has a rough specific surface and large porosity, and heavy metals can be loaded on the burning fly ash, so the burning fly ash has large harm to the environment. At present, most of the methods adopt an immobilization treatment technology or a stabilization treatment technology, and a common method for immobilization treatment is cement solidification treatment.
In view of the above-mentioned related technologies, the inventor believes that after the incineration fly ash is simply cured by using the cement curing agent, the encapsulation effect of the cured object is not good, and the heavy metal ions encapsulated in the cured object are easy to leach out, which causes environmental pollution, thereby causing the curing agent to have the defect of poor incineration fly ash curing effect.
Disclosure of Invention
In order to improve the defect that the curing effect of the curing agent on the incineration fly ash is not good, the application provides a curing agent for heavy metals in the incineration fly ash of household garbage and a fixing method applying the curing agent.
In a first aspect, the application provides a curing agent for heavy metals in fly ash from incineration of household garbage, which adopts the following technical scheme:
a heavy metal curing agent in household garbage incineration fly ash comprises the following substances in parts by weight: 20-30 parts of cement, 6-10 parts of metakaolin, 10-15 parts of slag, 5-9 parts of water, 5-10 parts of red mud and 10-15 parts of an additive, wherein the additive comprises a stabilizer which comprises sludge biochar and fishbone powder in a mass ratio of 5-9.
By adopting the technical scheme, as the cement, the metakaolin, the slag and the red mud are matched with each other, the slag and the red mud are industrial wastes, and the slag, the red mud and other wastes are treated while the incineration fly ash is solidified, so that the environment is protected. The proportion of each component in the curing agent is adjusted, and the components of the curing agent are mutually matched, so that the doping amount of the incineration fly ash in the curing agent can be effectively increased, namely, the content of the curing agent required by the same mass of fly ash is reduced, and the compatibilization of a cured product is reduced.
Secondly, this application adopts to increase the additive in the curing agent, and mud biochar and fishbone powder mutually support, and mud biochar is made by municipal sludge, and fishbone powder is made by abandonment fishbone, and the additive also adopts municipal waste to make, can handle multiple discarded object simultaneously, environmental protection more simultaneously.
In addition, the additive has a rough surface structure, and also has active hydroxyapatite and various active organic groups, and thus, metal ions in the incineration fly ash can be attracted and form a complex through complexation, electrostatic adsorption, ion exchange, and the like. Meanwhile, the complex can be stably adsorbed and loaded on the rough surface structure of the additive, when heavy metal ions in the complex loaded on the additive escape, the additive can chelate the heavy metal ions again, the possibility of leaching of the heavy metal ions is stably reduced, and the possibility of causing danger to the environment by a solidified product is reduced, so that the solidifying agent has a better solidifying effect on the incineration fly ash.
Preferably, the additive also comprises an exciting agent, wherein the exciting agent comprises strontium carbonate waste residue and potassium carbonate in a mass ratio of 2-3.
By adopting the technical scheme, the strontium carbonate waste residue and the potassium carbonate are matched, and the potassium carbonate can activate the strontium carbonate waste residue, so that Si and Al in the strontium carbonate waste residue are excited, silicon-oxygen bonds are broken, and an unstable bond structure is generated. Along with the curing process of the incineration fly ash by the curing agent, an unstable bond structure in the activator is combined with the incineration fly ash and silicon ions in the curing agent, so that a stable gelled material is more easily formed in a cured product, the overall strength of the cured product is enhanced, the possibility of exposure of heavy metals in the cured product due to crushing of the cured product is reduced, and the curing effect of the curing agent on the incineration fly ash is stably improved.
Preferably, the sludge biochar is modified by a modifier, the modifier comprises ammonia water, straw powder and bacillus subtilis, the mass ratio of the ammonia water to the straw powder is 3-5 -1 。
Through adopting above-mentioned technical scheme, mutually support through aqueous ammonia, straw powder and Bacillus subtilis and carry out modification treatment to the biological charcoal of mud, the addition of straw powder can effectively increase the output of the biological charcoal of mud to reduce cost can also reduce the ash content of the biological charcoal of mud, increases the roughness on surface of the biological charcoal of mud, improves the absorption load effect of the biological charcoal of mud to the complex.
Meanwhile, the bacillus subtilis is more stably loaded on the sludge biochar, when the incineration fly ash is solidified by the curing agent, the bacillus subtilis can induce a volcanic ash reaction in a solidified product to generate cemented crystals such as calcium carbonate, calcium silicate hydrate and the like, the cemented crystals can increase the strength of the solidified product, and can also coat a complex loaded on the sludge biochar and the incineration fly ash, so that the coating effect on heavy metal ions is enhanced.
In addition, the addition of ammonia water enables more amino active groups to be added on the sludge activated carbon, so that the adsorption capacity and the adsorption rate of the biochar are increased, the adsorption and complexing effects of the sludge activated carbon on heavy metal ions are stably enhanced, and the possibility of leaching of the heavy metal ions is further reduced. Therefore, more amino active groups are grafted on the sludge biochar modified by the modifier and the bacillus subtilis is loaded, so that after the stabilizer is combined with the activator, the activation of Si and Al in the activator is promoted, the content of a gel in a cured product is further enhanced, the strength of the cured product is stably improved, and the leaching possibility of heavy metals is reduced.
Preferably, the preparation of the sludge biochar comprises the following steps: respectively weighing 5-8 parts of dewatered sludge, 5-8 parts of straw powder, 3-5 parts of ammonia water, 1 part of epoxy resin, 10 parts of sulfuric acid, 10 parts of nitric acid and 0.1 part of sodium hydrosulfite by weight; drying, crushing and screening dewatered sludge to obtain sludge powder, stirring and mixing the sludge powder and straw powder to obtain mixed powder, and performing pyrolysis carbonization on the mixed powder in an oxygen-free environment to obtain biochar; stirring and mixing the biochar, sulfuric acid and nitric acid, cooling, carrying out suction filtration and washing to obtain a nitration product, stirring and mixing the nitration product, ammonia water and sodium hydrosulfite, and filtering to obtain a primary productThe viable bacteria count is 4000-6000 CFU g -1 The bacillus subtilis, the epoxy resin and the primary product are stirred and mixed to prepare the modified sludge biochar.
By adopting the technical scheme, the straw powder and the dewatered sludge are firstly mixed and carbonized together, so that the straw powder is used for doping and modifying the sludge activated carbon, and the yield of the sludge activated carbon is improved. And then, the biochar is loaded with amino groups, so that the surface activity of the biochar is improved, the biochar is easy to form crosslinking with epoxy resin, and the bacillus subtilis is stably loaded on the biochar.
Preferably, the temperature of the pyrolysis treatment is 300-500 ℃, and the heating rate is 5-15 ℃/min.
Through adopting above-mentioned technical scheme, this application technical scheme has optimized the pyrolysis temperature and the rate of rise of temperature of the carbonization in-process of mud biochar, and suitable pyrolysis temperature for dewatered sludge and straw powder can comparatively even pyrolysis carbonization, promote the carbonization process to go on, improve the biochar output. Meanwhile, the proper pyrolysis temperature enables the biological activated carbon to obtain a larger specific surface area, and the surface aromatizing degree of the biological activated carbon can be increased, namely the biological activated carbon obtains more surface active groups, and the biological activated carbon can stably adsorb heavy metal ions to form a complex product, thereby being beneficial to the curing effect of the curing agent on the incineration fly ash.
Preferably, the additive also comprises a chelating agent, wherein the chelating agent comprises ethidium azide, sodium sulfide and ethylenediamine tetraacetic acid, and the mass ratio of the ethidium azide to the sodium sulfide to the ethylenediamine tetraacetic acid is 1.
Through adopting above-mentioned technical scheme, this application technical scheme adopts nitrogen ethide, sodium sulfide and ethylenediamine tetraacetic acid to mutually support as the chelator, adopts organic and inorganic compound mode to carry out stabilization treatment to the heavy metal ion in the fly ash that burns, reduces the selectivity of chelator to heavy metal, increases the chelation effect of chelator to different heavy metal ions to improve the stability of chelate. In addition, the proportion of each component in the chelating agent is optimized, the content of the ethylene diamine tetraacetic acid is controlled, the chelating effect of the chelating agent on heavy metal ions is improved, the content of organic matters is reduced, and the cost of the chelating agent is reduced.
In a second aspect, the application provides a method for fixing and stabilizing heavy metals in fly ash generated by burning household garbage, which adopts the following technical scheme:
a method for fixing and stabilizing heavy metals in household garbage incineration fly ash comprises the following steps: s1, premixing treatment: weighing an additive and incineration fly ash according to a mass ratio of 1-2; s2, stabilizing treatment: stirring and mixing metakaolin, slag, red mud and the premix, ball-milling and sieving to obtain an intermediate product, sintering the intermediate product, and cooling to obtain ceramsite; s3, curing treatment: taking the incineration fly ash and the ceramsite according to the mass ratio of 1.
By adopting the technical scheme, the additive is mixed with the incineration fly ash firstly, so that the additive firstly chelates, complexes, adsorbs ions and the like to heavy metal ions contained in the incineration fly ash to form a primary complex, and the heavy metal ions are subjected to primary curing treatment. And then sintering the slag, the red mud and the premix to prepare ceramsite, wherein the ceramsite has a plurality of pore structures, so that the incineration fly ash can be coated again, and heavy metal leaching in the incineration fly ash is further prevented. And finally, mixing the cement, the ceramsite, the metakaolin and the incineration fly ash, wherein the cement and the metakaolin can form a gelled structure in the curing process, the gelled structure can be matched with the pore structure of the ceramsite, and finally a staggered and stable skeleton structure is formed, so that the strength of a cured product is stably improved, the wrapping effect of a curing agent on the incineration fly ash is improved, and the curing effect of the curing agent on the incineration fly ash is enhanced.
Preferably, before the pre-mixing treatment, the incineration fly ash is pre-treated, and the pre-treatment comprises the following steps: taking the incineration fly ash and phosphoric acid according to the mass ratio of 1.
Through adopting above-mentioned technical scheme, this application technical scheme adopts phosphoric acid to carry out the preliminary treatment to incineration fly ash, under the leaching of phosphoric acid, and partial heavy metal ion in the incineration fly ash leaches in advance, and makes incineration fly ash be acidic, is favorable to carrying out reactions such as complex, chelation between follow-up incineration fly ash and the curing agent, and heavy metal ion is changeed into the form that is difficult for leaching, improves the stability of solidification product cladding heavy metal ion.
Preferably, the preheating temperature in the sintering treatment is 350-400 ℃, the sintering temperature is 1050-1250 ℃, and the sintering time is 20-30min.
By adopting the technical scheme, the preheating temperature, the sintering temperature and the sintering time are optimized, so that the molten liquid phase of the ceramsite is increased in the sintering process, the structure of the ceramsite is more compact, the ceramsite with a more compact structure is obtained, and meanwhile, the water absorption effect of the ceramsite is reduced, namely, the possibility that the ceramsite is contacted with water to leach heavy metal ions during curing treatment is reduced, the strength of a cured product is improved, and the curing effect of a curing agent on incineration fly ash can be enhanced.
In summary, the present application has the following beneficial effects:
1. as the slag, the red mud, the cement, the metakaolin, the sludge biochar, the fishbone powder and the like are used as the curing agent, most of the incineration fly ash is treated by industrial and domestic wastes, and various pollutants and wastes are synchronously treated in the curing treatment process, so that the method is environment-friendly; meanwhile, the components in the curing agent are matched with each other, so that the amount of the incineration fly ash curable by the curing agent can be effectively increased, a stable curing product is formed by complexing, electrostatic adsorption, ion exchange and other modes, and the selectivity of the curing agent on heavy metal ions is reduced, so that the curing agent obtains a stable curing effect on the incineration fly ash.
2. According to the method, ammonia water, straw powder and bacillus subtilis are preferably adopted to be matched to modify the sludge biochar, so that on one hand, the yield of the sludge biochar is increased, the ash content of the sludge biochar is reduced, and the specific surface area of the sludge activated carbon is increased; on the other hand, more active functional groups are grafted on the surface of the sludge activated carbon, so that the adsorption and complexing effects of the sludge activated carbon on heavy metal ions are enhanced.
3. According to the method, the slag, the red mud and the premix are sintered to prepare the ceramsite, the incineration fly ash can be further loaded through the ceramsite, and meanwhile, the ceramsite can be matched with a gel structure generated when the curing agent is cured to form a staggered and complex skeleton structure, so that the strength of a cured product is further improved, the possibility of cracking the cured product and exposing heavy metal is reduced, and the effect of stably curing the heavy metal ions by the curing agent is achieved.
Detailed Description
The present application will be described in further detail with reference to examples.
In the embodiment of the present application, the selected apparatuses are as follows, but not limited thereto:
the instrument comprises the following steps: TH-JMZZ type roaster of Kyochu New Material science and technology Co., ltd;
medicine preparation: ethylene diamine tetraacetic acid with 99% of Shandong Qianfan Shunhua chemical industry Co., ltd, ethionam with 94% of Yunnan Sufuu Shangma, metakaolin with 52% of silicon dioxide content of Shijiazhuang Jing mineral product Co., ltd, phoenix 6101 (E44) epoxy resin of Luoyang Yixuan Industrial trade Co., ltd, and Bacillus subtilis of Jinnan Shundada Biotech Co., ltd.
Preparation examples
Preparation of chelating agent
Preparation examples 1 to 3
And respectively weighing ethidium nitrogen, sodium sulfide and ethylene diamine tetraacetic acid, wherein the specific mass is shown in table 1, and stirring and mixing to obtain the chelating agent 1-3.
TABLE 1 preparative examples 1-3 chelant compositions
Examples of preparation of exciting agent
Preparation examples 4 to 6
Respectively weighing strontium carbonate waste residue and potassium carbonate, wherein the specific mass is shown in Table 2, stirring and mixing to prepare 1-3 exciting agents, and the strontium carbonate waste residue is solid waste generated in the production of strontium carbonate salt.
TABLE 2 preparation examples 4-6 exciting agent compositions
Preparation example of sludge biochar
Preparation example 7
Weighing 5kg of dewatered sludge, crushing, sieving, grinding, sieving by a 60-mesh sieve to obtain sludge powder, placing the mixed powder in an oxygen-free and nitrogen atmosphere, heating to 300 ℃ at a speed of 5 ℃/min, and pyrolyzing for 2h to obtain biochar which is used as sludge biochar 1.
Preparation examples 8 to 10
Dehydrated sludge, 60-mesh straw powder, bacillus subtilis, 25% ammonia water by mass fraction, epoxy resin, 98% sulfuric acid by mass fraction, 65% nitric acid by mass fraction, sodium bisulfite and glacial acetic acid are respectively weighed, and the specific mass is shown in table 3.
Drying the dewatered sludge at 40 ℃, crushing, screening, grinding, sieving by a 60-mesh sieve to obtain sludge powder, and stirring and mixing the sludge powder and straw powder to obtain mixed powder. And (3) putting the mixed powder in an oxygen-free and nitrogen atmosphere, heating to 300 ℃ at the speed of 5 ℃/min, and pyrolyzing for 2h to obtain the biochar. Firstly, sulfuric acid and nitric acid are placed in a salt bath for stirring and mixing to prepare an oxidation solution, biochar is added into the oxidation solution, stirring and reacting are carried out for 2 hours, cooling, suction filtration, deionization, isopropanol washing and drying are carried out, and a nitration product is obtained. Mixing the nitration product, ammonia water and water under stirring, adding sodium disulfite, stirring for 20h, adding glacial acetic acid, heating to 100 deg.C, refluxing for 5h, and filtering to obtain primary product. Stirring and mixing the bacillus subtilis and the epoxy resin to prepare a bonding material, and stirring and mixing the bonding material and the primary product to obtain the modified sludge biochar 1-3.
TABLE 3 preparation examples 8-10 sludge biochar compositions
TABLE 4 preparation examples 8 to 10 Bacillus subtilis
Preparation example 12
The difference from preparation 9 is that: the heating rate is 10 ℃/min, the pyrolysis temperature is 400 ℃, and the modified sludge biochar 4 is obtained.
Preparation example 13
The difference from preparation 9 is that: the heating rate is 15 ℃/min, the pyrolysis temperature is 500 ℃, and the modified sludge biochar 5 is obtained.
Preparation example 14
The difference from preparation example 7 is that: weighing 4kg of ammonia water, 6.5kg of straw powder and 1.5kg of bacillus subtilis, stirring and mixing to prepare a modifier, stirring and mixing the modifier and the sludge biochar 1, and filtering to obtain modified sludge biochar 6.
Preparation of stabilizer
Preparation examples 15 to 17
Sludge biochar 1 and fishbone powder are respectively weighed to prepare 1-3 stabilizers, and the specific mass is shown in Table 5.
TABLE 5 preparation examples 15-17 stabiliser compositions
Preparation examples 18 to 23
The difference from preparation 16 is that: the modified sludge biochar 1-6 is adopted to replace the sludge biochar 1 in the preparation example 16 to prepare the stabilizer 4-9.
Examples of preparation of additives
Preparation examples 24 to 26
Respectively weighing the stabilizer 1, the excitant 1 and the chelating agent 1, wherein the specific mass is shown in Table 6, and stirring and mixing to obtain the additives 1-3.
TABLE 6 preparation examples 18-20 additive compositions
Preparation examples 27 to 34
The difference from preparation 18 is that: additives 4 to 11 were prepared using stabilizers 2 to 9 instead of stabilizer 1 in preparation example 1.
Preparation examples 35 to 36
The difference from preparation example 20 is that: additives 12 to 13 were prepared using activators 2 to 3 instead of activator 1 in preparation example 1.
Preparation examples 37 to 38
The difference from preparation example 20 is that: additives 14-15 were prepared using chelating agents 2-3 instead of chelating agent 1 in preparation example 1.
Examples
Example 1
On the one hand, the application provides a heavy metal curing agent in domestic waste incineration fly ash, contains following substance: the concrete quality of the cement, the metakaolin, the slag, the red mud and the additive 1 is shown in a table 7.
Table 7 examples 1-3 sludge biochar compositions
On the other hand, the application provides a method for fixing heavy metals in household garbage incineration fly ash by using a curing agent, which comprises the following steps: pre-mixing treatment: 20kg of incineration fly ash and 10kg of additive 1 are taken and stirred and mixed to prepare the premix. And (3) stabilizing treatment: stirring and mixing metakaolin, slag, red mud and the premix, ball-milling, sieving by a 100-mesh sieve to obtain an intermediate product, placing the intermediate product in a roasting furnace, preheating the roasting furnace at 350 ℃, sintering at 1050 ℃, sintering for 20min, and cooling to obtain ceramsite. Curing treatment: 5kg of incineration fly ash and ceramsite are stirred and mixed to obtain aggregate, the aggregate, water and cement are stirred and mixed, and standing is carried out to obtain a solidified product 1-3.
Example 4
The difference from example 2 is that: the preheating temperature in the roasting furnace is 420 ℃, the sintering temperature is 1155 ℃, and the sintering time is 25min, so that a cured product 4 is prepared.
Example 5
The difference from example 2 is that: the preheating temperature in the roasting furnace is 500 ℃, the sintering temperature is 1250 ℃, and the sintering time is 30min, thus obtaining the cured product 5.
Examples 6 to 19
The difference from example 2 is that: cured products 6 to 19 were prepared using additives 2 to 15 instead of additive 1 in example 2.
Example 20
The difference from example 2 is that: and (3) pretreating the incineration fly ash before premixing, weighing 3kg of incineration fly ash and 3kg of phosphoric acid, stirring and mixing, filtering, and drying to obtain the pretreated incineration fly ash. The incineration fly ash of example 2 was replaced with the pretreated incineration fly ash to obtain a solidified material 20.
Example 21
The difference from example 2 is that: and (3) pretreating the incineration fly ash before premixing, weighing 3kg of incineration fly ash and 4.5kg of phosphoric acid, stirring and mixing, filtering, and drying to obtain the pretreated incineration fly ash. The incineration fly ash of example 2 was replaced with the pretreated incineration fly ash to obtain a solidified material 21.
Example 22
The difference from example 2 is that: and (3) pretreating the incineration fly ash before premixing, weighing 3kg of incineration fly ash and 6kg of phosphoric acid, stirring and mixing, filtering, and drying to obtain the pretreated incineration fly ash. The incineration fly ash of example 2 was replaced with the pretreated incineration fly ash to obtain a solidified material 22.
Comparative example
Comparative example 1
This comparative example differs from example 2 in that it uses only cement as a curing agent to produce a cured product 23.
Comparative example 2
This comparative example is different from example 2 in that fly ash from incineration was directly mixed with a curing agent with stirring without stabilization treatment to obtain a cured product 24.
Performance test
1. Leaching detection of heavy metal ions: the solidified product is detected according to a method of 'HJ/T300-2007 solid waste leaching toxicity leaching method acetic acid buffer solution method', the leaching concentrations of Cu, zn, cr, ni, cd, pb, hg and As are recorded, and evaluation is carried out according to GB16889-2008 'domestic garbage landfill pollution control Standard', wherein the leaching concentrations of Cd, hg and As are all low, and leaching is almost not carried out, so that detection is not carried out.
2. And (3) detecting the pressure resistance: performing tests according to GB/T17671-1999 Cement mortar Strength test method (ISO method), wherein the weight ratio of the test sample to the cement mortar is 1:3, mixing cement and standard sand according to a water-cement ratio of 0.5 to prepare a group of mortar, curing for 28 days under standard curing conditions, wherein the mortar test block specification is 40mm multiplied by 40mm, and recording the compressive strength.
TABLE 8 Performance test of examples 1 to 22 and comparative examples 1 to 2
TABLE 9 Performance test of examples 1-22 and comparative examples 1-2
Referring to the comparison of the performance tests in tables 8 and 9, it can be found that:
(1) A comparison of examples 1 to 3 with comparative example 1 shows that: the heavy metal dissolution concentration of the cured product prepared in examples 1 to 3 is reduced and the compressive strength is improved, which shows that the application adopts the combination of cement, red mud, metakaolin and the like, and can effectively attract heavy metal ions in the incineration fly ash and form a complex compound through the modes of complexation, electrostatic adsorption, ion exchange and the like, and the proportion of the incineration fly ash in the cured product is increased, so that the curing effect of the curing agent is stably improved. As can be seen from tables 8 and 9, the cured product obtained in example 2 has the lowest concentration of dissolved heavy metal and higher compressive strength, which indicates that the ratio of the components in the curing agent is more suitable.
(2) A comparison of example 2, examples 4 to 5 and comparative example 2 shows that: the heavy metal dissolution concentration of the cured product prepared in the examples 4-5 is reduced, and the compressive strength is improved, which shows that the application carries out stabilization treatment at a proper temperature to prepare ceramsite, on one hand, a gel and a staggered skeleton structure of the ceramsite are formed in the cured product, and the strength of the cured product is stably enhanced; on the other hand, the ceramsite can load the incineration fly ash and encapsulate the incineration fly ash, so that the possibility of leaching heavy metal ions is reduced. As is apparent from tables 8 and 9, the solidified product obtained in example 5 has the lowest concentration of the dissolved heavy metal and the higher compressive strength, indicating that the respective parameters of the sintering treatment are suitable.
(3) A comparison of the combinations of example 2, examples 6 to 7 and examples 8 to 9 shows that: the cured products obtained in examples 6 to 9 have a reduced concentration of dissolved heavy metals and an improved compressive strength, which indicates that the present application employs a combination of a stabilizer, an activator and a chelating agent to increase the number of surface active groups of the curing agent, improve the chelating and complexing effects of the curing agent on heavy metal ions, and increase the number of gelled products during curing treatment, i.e., to enhance the complexity of the gelled network structure in the cured product and improve the strength of the cured product. As can be seen from Table 8, the cured products obtained in examples 7 and 8 had a low concentration of eluted heavy metals and a high compressive strength, indicating that the additive in example 7 had a suitable ratio of the components and the stabilizer in example 8 had a suitable ratio of the components.
(4) By combining the comparison of example 2 and examples 10 to 15, the following results can be found: the heavy metal dissolution concentration of the cured products prepared in examples 10 to 15 is reduced and the compressive strength is improved, which shows that ammonia water, straw powder and bacillus subtilis are adopted to cooperate to modify the sludge biochar, so that the surface active groups of the sludge biochar are increased, the loading effect of the bacillus subtilis is enhanced, the gelling reaction in the curing treatment is stably promoted, the cooperation effect between the stabilizer and the activator is improved, and the curing effect of the curing agent on heavy metal ions is synergistically improved. As can be seen from Table 8, the cured products obtained in examples 11 and 13 had low concentrations of heavy metals dissolved out and high compressive strength, indicating that the proportions of the components in the sludge biochar in example 11 were suitable and the parameters in the pyrolysis treatment in example 13 were suitable.
(5) A comparison of the results obtained in connection with examples 2, 6 to 7 and 16 to 17 shows that: the cured products obtained in examples 16 to 17 were reduced in the concentration of dissolved heavy metals and improved in compressive strength, which indicates that the use of strontium carbonate waste residues and potassium carbonate in combination as an activator increased the contents of activated Si and Al in the curing agent, promoted the formation of a gel structure, and improved the strength of the cured products. As is apparent from Table 8, the cured product obtained in example 16 had the lowest concentration of the dissolved heavy metal and the higher compressive strength, indicating that the components of the initiator were suitably mixed.
(6) A comparison of the results obtained in connection with examples 2, 6 to 7 and 18 to 19 shows that: the heavy metal dissolution concentration of the cured products prepared in examples 18 to 19 is reduced and the compressive strength is improved, which shows that the application adopts the mutual cooperation of ethionamide, sodium sulfide and ethylene diamine tetraacetic acid, so that the chelation effect of the curing agent on heavy metal ions is enhanced, and the selectivity of the curing agent on the heavy metal ions is reduced, namely, the curing agent can chelate the heavy metal ions widely. As can be seen from Table 8, the solidified product obtained in example 18 had the lowest concentration of the dissolved heavy metal and the higher compressive strength, indicating that the respective components in the chelating agent were suitably mixed.
(7) A comparison of examples 20 to 22 with comparative example 2 shows that: the cured products obtained in examples 20 to 22 had a reduced concentration of dissolved heavy metal and an improved compressive strength, which indicates that the incineration fly ash was pretreated with phosphoric acid to leach heavy metal ions from the incineration fly ash to a certain extent, thereby reducing the content of heavy metal ions in the incineration fly ash during curing treatment and stably reducing the possibility of leaching heavy metal ions from the cured products. As can be seen from tables 8 and 9, the cured product obtained in example 21 had the lowest concentration of dissolved heavy metal and a high compressive strength, indicating that the respective component proportions in the pretreatment were appropriate.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (6)
1. The curing agent for heavy metals in the household garbage incineration fly ash is characterized by comprising the following substances in parts by weight: 20-30 parts of cement, 1-3 parts of metakaolin, 10-15 parts of slag, 5-9 parts of water, 5-10 parts of red mud and 10-15 parts of an additive, wherein the additive comprises a stabilizer which comprises sludge biochar and fishbone powder in a mass ratio of 5-9;
the preparation method of the sludge biochar comprises the following steps:
respectively weighing the following substances in parts by weight: 5-8 parts of dewatered sludge, 5-8 parts of straw powder, 3-5 parts of ammonia water, 1 part of epoxy resin, 10 parts of sulfuric acid, 10 parts of nitric acid and 0.1 part of sodium hydrosulfite;
drying, crushing and screening dewatered sludge to obtain sludge powder, stirring and mixing the sludge powder and straw powder to obtain mixed powder, and performing pyrolysis carbonization on the mixed powder in an oxygen-free environment to obtain biochar; stirring and mixing biochar, sulfuric acid and nitric acid, cooling, performing suction filtration and washing to obtain a nitration product, stirring and mixing the nitration product, ammonia water and sodium hydrosulfite, filtering to obtain a primary product, and controlling the viable count to be 4000-6000 CFU.g -1 Stirring and mixing the bacillus subtilis, the epoxy resin and the primary product to prepare modified sludge biochar;
the temperature of the pyrolysis treatment is 400 ℃, and the heating rate is 10 ℃/min.
2. The curing agent for heavy metals in fly ash from incineration of household garbage according to claim 1, characterized in that: the additive also comprises an excitant, wherein the excitant comprises strontium carbonate waste residue and potassium carbonate with the mass ratio of 2-3.
3. The curing agent for heavy metals in fly ash from incineration of household garbage according to claim 1, characterized in that: the additive also comprises a chelating agent, wherein the chelating agent comprises ethidium nitrate, sodium sulfide and ethylene diamine tetraacetic acid, and the mass ratio of the ethidium nitrate to the sodium sulfide to the ethylene diamine tetraacetic acid is 1.
4. A method for fixing heavy metals in fly ash from incineration of household garbage by using the curing agent according to any one of claims 1 to 3, comprising the steps of:
s1, premixing treatment: weighing an additive and incineration fly ash according to the mass ratio of 1-2:1-1.05, and stirring and mixing to prepare a premix;
s2, stabilizing treatment: stirring and mixing metakaolin, slag, red mud and the premix, ball-milling and sieving to obtain an intermediate product, sintering the intermediate product, and cooling to obtain ceramsite;
s3, curing treatment: taking the incineration fly ash and the ceramsite according to the mass ratio of 1.
5. The method for immobilizing heavy metals in fly ash from incineration of household garbage according to claim 4, wherein the fly ash from incineration is pretreated before the pre-mixing treatment, and the pretreatment comprises the following steps: taking incineration fly ash and phosphoric acid according to the mass ratio of 1.
6. The method for fixing heavy metals in fly ash from incineration of household garbage according to claim 4, wherein the method comprises the following steps: the preheating temperature in the sintering treatment is 350-400 ℃, the sintering temperature is 1050-1250 ℃, and the sintering time is 20-30min.
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| CN116082057A (en) * | 2023-01-29 | 2023-05-09 | 山东山科生态环境研究院有限公司 | Method for reducing volatilization of heavy metals in ceramsite preparation process by using red mud |
| CN117046881B (en) * | 2023-10-11 | 2024-02-27 | 杭州尚善若水环保科技有限公司 | Resource utilization method of waste incineration fly ash |
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