CN115710112B - Composite curing agent for dredging sludge and preparation method and application thereof - Google Patents
Composite curing agent for dredging sludge and preparation method and application thereof Download PDFInfo
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- CN115710112B CN115710112B CN202211506254.1A CN202211506254A CN115710112B CN 115710112 B CN115710112 B CN 115710112B CN 202211506254 A CN202211506254 A CN 202211506254A CN 115710112 B CN115710112 B CN 115710112B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention belongs to the technical field of sludge curing agents, and discloses a dredging sludge composite curing agent, a preparation method and application thereof. The composite curing agent comprises the following raw materials in percentage by mass: 41 to 54 percent of quicklime, 37 to 42 percent of cement, 4 to 8 percent of alkali metal aluminosilicate, 4.5 to 8 percent of nano titanium dioxide and 0.5 to 2 percent of silane coupling agent. The composite curing agent overcomes the difficult problem of curing the sludge with high organic matter content, can degrade the organic matters in the sludge and fix CO generated by degradation 2 The formed solidified body has high strength, good stability and difficult cracking, can be used as a building material, and realizes win-win effect of environment and economy.
Description
Technical Field
The invention belongs to the technical field of sludge curing agents, and particularly relates to a dredging sludge composite curing agent, a preparation method and application thereof.
Background
Sediment dredging, which is a method for reducing the release of pollutants in sediment to a water body by dredging the sediment, is widely used as an important means for water environment treatment. The sediment dredging can permanently remove pollutants in the sediment, effectively reduce endogenous pollution, and has better effect on improving water quality, but a large amount of sludge is generated in the dredging process, such as bad treatment, and serious secondary pollution is caused.
During the past decade, the treatment and disposal of dredging sludge has been mainly ocean disposal and land landfill. With the increase of the sludge amount, the capacity of the offshore mud throwing area is approaching saturation, and the offshore mud throwing is continued to cause ocean pollution, so that adverse effects are caused on an ocean ecosystem. Land landfills, although low in cost, are increasingly in shortage in storage yards in China, cannot meet the requirement of stacking land for a large amount of sludge, and still have the risk of leaching out sludge pollutants in the stacking process. Therefore, there is an urgent need to explore effective sludge treatment disposal techniques.
In recent years, research at home and abroad is increasingly prone to curing treatment and resource utilization of sludge, and a series of physicochemical reactions are caused by doping chemical curing agents into the sludge, so that the purposes of improving the physical and mechanical properties of the sludge, stabilizing pollutants and the like are achieved. The method can not only make the sludge harmless, but also can make the solidified sludge reach the application performance requirement of the building engineering through rolling forming and maintenance, thereby realizing the recycling utilization, and being a treatment method recommended to be adopted in many developed countries.
At present, more curing agents are mainly cement and lime, but the application of the cement and the lime to the sludge curing has certain defects, namely poor stability, easy cracking, low strength and the like of a cured body, and the most outstanding problems are that the cement and the lime have high requirements on the properties of the sludge, narrow application range and poor curing effect on the sludge with high organic matter content. The difficulty in curing the sludge with high organic matter content is mainly that humic acid and humins in the organic matter can be combined with clay mineral substances to generate inert parts, so that the cohesive force and internal friction angle of the sludge are greatly reduced, and the curing strength of the curing agent on the sludge is reduced; in addition, anaerobic fermentation of organic matters in the sludge can emit irritant gas to escape, so that the environment ecology is influenced, and the solidification strength is further influenced.
In view of the above, it is necessary to develop a new curing agent that produces a better curing effect for high organic matter content sludge to meet engineering demands.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a dredging sludge composite curing agent, a preparation method and application thereof, and the composite curing agent overcomes the problem of curing high-organic-matter-content sludge, can degrade organic matters in the sludge and fix CO generated by degradation 2 The formed solidified body has high strength, good stability and uneasy openingThe crack can be used as a building material to realize win-win of environment and economy.
In order to solve the technical problem, the invention provides a dredging sludge composite curing agent, which consists of the following raw materials in percentage by mass: 41 to 54 percent of quicklime, 37 to 42 percent of cement, 4 to 8 percent of alkali metal aluminosilicate, 4.5 to 8 percent of nano titanium dioxide and 0.5 to 2 percent of silane coupling agent.
In the scheme, the particle size of the quicklime is less than or equal to 1mm, and the CaO content is more than or equal to 95%.
In the scheme, the cement is ordinary silicate cement, and the strength grade is more than 42.5R.
In the above scheme, the alkali aluminosilicate is Na 2 O·Al 2 O 3 ·2.45SiO 2 ·6.0H 2 O has a particle diameter of 0.4 to 1 μm.
In the scheme, the nano titanium dioxide is anatase hydrophilic nano titanium dioxide, the particle size is 15-50 nm, and the purity is more than 98%.
In the scheme, the silane coupling agent is PSI-500.
The invention also provides a preparation method of the dredging sludge composite curing agent, which comprises the following steps:
1) Mixing cement, quicklime and aluminosilicate and stirring uniformly to obtain a component A;
2) Mixing nano titanium dioxide and a silane coupling agent, and uniformly stirring to obtain a component B;
3) And mixing the component A and the component B and uniformly stirring to obtain the composite curing agent.
In the scheme, the stirring speed of each step is more than or equal to 400r/min.
In the scheme, the stirring time of the step 1) is 5-10 min, the stirring time of the step 2) is 15-20 min, and the stirring time of the step 3) is 3-5 min.
The invention also provides an application of the dredging sludge composite curing agent, which comprises the following steps: and (3) mixing the composite curing agent into the dredging sludge, uniformly stirring, and curing to obtain a cured body.
In the scheme, the organic matter content of the dredging sludge is more than 10%, and the water content is more than 45%.
In the scheme, the mixing amount of the composite curing agent is 10-30% of the mass of the dredging sludge.
In the above scheme, the maintenance conditions are as follows: maintaining at 22+/-1 deg.c and 75+/-2% humidity for 7-28 days.
The working principle of the composite curing agent of the invention is as follows:
when the composite curing agent is used for curing the sludge with high organic matter content, the organic matter in the sludge is degraded into CO through the nano titanium dioxide 2 And water, overcome the interference of organic matter to the solidification intensity development of silt; partial CO generated by degradation 2 And quicklime to generate a product for enhancing the mechanical strength of the mucky soil through a chemical combination reaction; part of the CO which has not reacted with the quicklime 2 The molecular sieve formed by the aluminosilicate is adsorbed and stored, carbon dioxide molecules in the molecular sieve can continuously react with quicklime after being slowly released, and the generated solidified substance wraps aluminosilicate particles, so that the nucleation effect of the aluminosilicate is exerted, and particles with larger particle size are formed, so that the strength of the mucky soil is further improved.
Compared with the prior art, the invention has the beneficial effects that:
the composite curing agent overcomes the difficult problem of curing the sludge with high organic matter content, can degrade organic matters in the sludge, eliminates the adverse effect of the organic matters on curing, and simultaneously can degrade CO generated by the organic matters 2 Fixing the catalyst by physical adsorption and chemical reaction conversion to prevent CO 2 The method has the advantages that the carbon emission is increased by escaping, the purpose of carbon fixation and emission reduction is achieved, the formed solidified body is high in strength, good in stability and compact in structure, can be used for construction projects such as road subgrade filling, base layer and subbase layer construction, a new way is provided for the solidification treatment comprehensive utilization of dredging sludge, the difficult problem of dredging sludge is solved, the current situation of shortage of road construction materials can be relieved, and win-win situation of environment and economy is realized.
Drawings
FIG. 1 is an external view of a cured product of example 3, cured 28 d.
FIG. 2 is an external view of the cured product of comparative example 1, 28 d.
FIG. 3 is an external view of the cured product of comparative example 2, 28 d.
FIG. 4 is an external view of the cured 28d article of comparative example 3.
FIG. 5 is an external view of the cured 28d article of comparative example 4.
Detailed Description
For a better understanding of the present invention, the following examples are further illustrated, but are not limited to the following examples.
In the following examples, the quicklime is selected as industrial calcium oxide powder, the grain diameter is about 1 μm, and the CaO content is more than or equal to 95%; the cement is ordinary silicate cement, and the strength grade is 42.5R; the alkali metal aluminosilicate is Na 2 O·Al 2 O 3 ·2.45SiO 2 ·6.0H 2 O, the grain diameter is 0.4-1 mu m; the selected nano titanium dioxide is anatase type hydrophilic nano titanium dioxide, the particle size is 15-50 nm, and the purity is more than 98%; the silane coupling agent is PSI-500 type silane coupling agent.
In the following examples, the dredging sludge selected was obtained from the marshallot of the Wuhan south lake, and had a blackish brown color, an organic matter content of 12.3%, a natural water content of 56.8%, a liquid limit of 55.3, and a plastic limit of 38.7, and was organic peat soil.
Examples 1 to 6
The dredging sludge composite curing agent in examples 1-6 consists of quicklime, cement, alkali metal aluminosilicate, nano titanium dioxide and a silane coupling agent, wherein the mass percentages of the components are shown in table 1.
TABLE 1 composition of composite curing agent of examples 1-6
The preparation method of the dredging sludge composite curing agent in the examples 1-6 comprises the following steps:
1) Mixing cement, quicklime and aluminosilicate and stirring uniformly to obtain a component A;
2) Mixing nano titanium dioxide and a silane coupling agent, and uniformly stirring to obtain a component B;
3) And mixing the component A and the component B and uniformly stirring to obtain the composite curing agent.
TABLE 2 essential parameters for the preparation of the composite curing agents of examples 1-6
The dredging sludge composite curing agent in the examples 1-6 is applied by the following method: and (3) mixing the composite curing agent into the dredging sludge, uniformly stirring, and curing to obtain a cured body. The results of the performance test are shown in Table 4, and the curing effect is shown in FIG. 1.
TABLE 3 essential parameters for the application of the composite curing agents of examples 1-6
Comparative example 1
Comparative example 1 differs from example 3 only in that: the composite curing agent is not added with nano titanium dioxide.
Comparative example 2
Comparative example 2 differs from example 3 only in that: the composite curing agent is not added with quicklime and alkali metal aluminosilicate.
Comparative example 3
Comparative example 3 differs from example 3 only in that: quicklime is not added into the composite curing agent.
Comparative example 4
Comparative example 4 differs from example 3 only in that: alkali aluminosilicate is not added into the composite curing agent.
To verify the effects of the above examples and comparative examples, the unconfined compressive strength, water stability, and organic matter content of the cured 28d bodies of each example and comparative example were tested, and the apparent condition of the cured bodies was recorded. The unconfined compressive strength is measured according to GB/T50123-2019 geotechnical test method standards; the water stability is subjected to a disintegration test according to the GB/T50123-2019 geotechnical test method standard, the disintegration amount of the solidified body after soaking in water for 24 hours is recorded, and the disintegration rate is calculated; the organic matter content was determined according to JTG E40-2007 Highway geotechnical test protocol. The results are shown in Table 4 and FIGS. 1 to 5.
Table 4 test results
From the data of examples 1 to 6, the organic matters in the dredged sludge are degraded after being treated by the composite curing agent, the water stability of the cured body is good, and the compressive strength is greatly improved. From fig. 1, it can be seen that the cured body has a compact structure and no significant air hole defects.
As can be seen from the test data of comparative example 1 and example 3, no nano TiO is added to the composite curing agent 2 Organic matters in the dredged silt are not degraded, the cementation of soil particles and a curing agent is affected, the structure of a cured body (figure 2) is loose, the water stability is poor, and the strength is low.
From the test data of comparative example 2 and example 3, it can be seen that the composite curing agent does not contain quicklime or aluminosilicate, carbon dioxide generated by degradation of organic matters in the dredged sludge escapes, and a large number of holes are generated in the cured body (figure 3), so that the strength of the cured body is limited to increase. Because organic matters in the dredging sludge are degraded, the cement soil in the composite curing agent can be well cemented with soil particles, and the water stability of the cured body is obviously improved compared with that of comparative example 1.
As can be seen from the test data of comparative example 3 and example 3, the composite curing agent does not add quicklime, the organic matters in the dredged sludge are degraded, the generated carbon dioxide cannot be chemically fixed, part of the gas is adsorbed and fixed by aluminosilicate, the unadsorbed gas escapes from the soil body, part of holes are generated in the cured body (fig. 4), the compactness is reduced, and the strength is reduced.
As can be seen from the test data of comparative example 4 and example 3, the composite curing agent does not contain aluminosilicate, the organic matter in the dredged sludge is degraded, the generated carbon dioxide part reacts with quicklime, the unreacted carbon dioxide escapes, and part of holes are generated in the cured body (fig. 5), and the strength is reduced.
The above examples are presented for clarity of illustration only and are not limiting of the embodiments. Other variations or modifications of the above description will be apparent to those of ordinary skill in the art, and it is not necessary or exhaustive of all embodiments, and thus all obvious variations or modifications that come within the scope of the invention are desired to be protected.
Claims (9)
1. The dredging sludge composite curing agent is characterized by comprising the following raw materials in percentage by mass: 41-54% of quicklime, 37-42% of cement, 4-8% of alkali aluminosilicate, 4.5-8% of nano titanium dioxide and 0.5-2% of silane coupling agent; the alkali aluminosilicate is Na 2 O·Al 2 O 3 ·2.45SiO 2 ·6.0H 2 O has a particle diameter of 0.4 to 1 μm.
2. The dredging sludge composite curing agent according to claim 1, wherein the nano titanium dioxide is anatase hydrophilic nano titanium dioxide, the particle size is 15-50 nm, and the purity is more than 98%.
3. The dredging sludge composite curing agent according to claim 1, wherein the quicklime has a particle size of less than or equal to 1mm and a CaO content of more than or equal to 95%; the cement is ordinary silicate cement with the strength grade of over 42.5R; the silane coupling agent is PSI-500.
4. A method for preparing a dredging sludge composite curing agent according to any one of claims 1-3, comprising the steps of:
1) Mixing cement, quicklime and aluminosilicate and stirring uniformly to obtain a component A;
2) Mixing nano titanium dioxide and a silane coupling agent, and uniformly stirring to obtain a component B;
3) And mixing the component A and the component B and uniformly stirring to obtain the composite curing agent.
5. The method for preparing the dredging sludge composite curing agent according to claim 4, wherein the stirring speed of each step is more than or equal to 400r/min; the stirring time of the step 1) is 5-10 min, the stirring time of the step 2) is 15-20 min, and the stirring time of the step 3) is 3-5 min.
6. Use of a dredging sludge complex curing agent according to any of claims 1-3, characterized in that the application method is: and (3) mixing the composite curing agent into the dredging sludge, uniformly stirring, and curing to obtain a cured body.
7. Use of a dredging sludge complex curing agent according to claim 6, characterised in that the dredging sludge has an organic content > 10% and a water content > 45%.
8. The application of the dredging sludge composite curing agent according to claim 6, wherein the mixing amount of the composite curing agent is 10% -30% of the mass of the dredging sludge.
9. Use of a dredging sludge complex curing agent according to claim 6, characterized in that the curing conditions are: maintaining at 22+/-1 ℃ and 75+/-2% of humidity for 7-28 days.
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| CN114538836A (en) * | 2022-03-17 | 2022-05-27 | 广东电网有限责任公司 | Soft soil curing agent, soft soil curing method and application thereof |
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Patent Citations (7)
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| JP2008231389A (en) * | 2007-03-20 | 2008-10-02 | Nagara Bionics Kk | Soil depurating and stabilizing agent |
| CN103771787A (en) * | 2014-02-20 | 2014-05-07 | 瑞昊（北京）环境工程有限公司 | Active powder soil solidifying agent as well as preparation method and application thereof |
| CN106082903A (en) * | 2016-06-17 | 2016-11-09 | 武汉大学 | A kind of dredging silt composite curing agent |
| CN109762423A (en) * | 2019-01-12 | 2019-05-17 | 陈国林 | A kind of preparation method preparing building external paint using paper mill sludge |
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