A cementing material for high water content sludge and a method of making the same

Abstract

The application discloses a cementing material for high-water-content sludge, which comprises the following components in parts by weight: 25-40 parts of Portland cement, 30-45 parts of lime, 15-30 parts of fly ash, 5-10 parts of modified papermaking black liquor, 10-25 parts of bentonite and 0.5-4 parts of anti-dispersing agent. The cementing material for high-water-content sludge prepared by the application can rapidly dewater the high-water-content sludge, improve the solidification strength of the high-water-content sludge, realize the resource utilization of the dredged sludge and reduce the pollution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cementing materials, in particular, relates to a cementing material for high water content silt and a preparation method thereof. BACKGROUND

[0002] There are many rivers and lakes in China, with the rapid development of shipping, it is necessary to dredge the rivers and lakes regularly to ensure the smoothness of shipping and reduce the pollution of bottom mud to water resources. The main methods of dredged silt treatment are ocean dumping and land dumping, but ocean dumping will pollute the marine environment, and land dumping will cause waste of land resources and secondary pollution, therefore, how to properly dispose of dredged silt is a difficult problem to be solved. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a cementing material for high water content silt, which can quickly dewater the high water content silt, improve the curing strength, realize the resource utilization of dredged silt and reduce pollution.

[0004] The technical problem to be solved by the present application is also to provide a preparation method of the cementing material for high water content silt, which is simple and does not require complex processing conditions.

[0005] To solve the above problems, the present application provides a cementing material for high water content silt, which comprises the following components in parts by weight: 25-40 parts of Portland cement, 30-45 parts of lime, 15-30 parts of fly ash, 5-10 parts of modified papermaking black liquor, 10-25 parts of bentonite and 0.5-4 parts of anti-dispersant.

[0006] In some embodiments, the anti-dispersant comprises polyacrylamide and sodium polyacrylate.

[0007] In some embodiments, the mass ratio of the polyacrylamide to the sodium polyacrylate is (1-2):1.

[0008] In some embodiments, the bentonite is sodium-based bentonite, and the polyacrylamide is anionic polyacrylamide.

[0009] In some embodiments, the mass ratio of the bentonite to the anti-dispersant is (4-5):1.

[0010] In some embodiments, the modified papermaking black liquor is prepared by the following method:

[0011] The papermaking black liquor is subjected to evaporation concentration treatment to obtain high-concentration papermaking black liquor;

[0012] Na2SO3 is added to the high-concentration papermaking black liquor and reacted at 140-160 DEG C for 0.5-1 h to obtain modified papermaking black liquor.

[0013] In some embodiments, the papermaking black liquor is papermaking black liquor produced in an alkaline pulping process.

[0014] The concentration of the high-concentration papermaking black liquor is 60-70%.

[0015] In some embodiments, the strength grade of the Portland cement is not lower than 42.5.

[0016] The lime is quicklime with an effective CaO content of not lower than 85%.

[0017] The fly ash is grade II fly ash.

[0018] To solve the above problems, the application further provides a preparation method of the cementing material for high-water-content sludge, in which Portland cement 25-40 parts, lime 30-45 parts, fly ash 15-30 parts, modified papermaking black liquor 5-10 parts, bentonite 10-25 parts and anti-dispersant 0.5-4 parts are mixed to obtain the cementing material for high-water-content sludge.

[0019] and application of the cementing material for high-water-content sludge in high-water-content sludge solidification.

[0020] The application has the following beneficial effects:

[0021] The application introduces Portland cement and lime in the formula, which can produce strength through hydration reaction and improve the mechanical properties of the sludge. Fly ash is also mixed in the formula, which can accelerate the hydration of the Portland cement and lime to produce strength and has the effects of volcanic ash and micro-aggregate, which can fill the pores of the sludge and improve the compactness. In addition, bentonite, anti-dispersant and modified papermaking black liquor are mixed in the formula, the bentonite can form strength through hydration as part of the cementing material, can absorb free water molecules and reduce the attenuation of the hydration strength of the solidified material due to excessive water content, the anti-dispersant can enhance the connection between the material and the sludge, block the excess free water, accelerate the dewatering of the sludge and improve the solidification strength of the cementing material on the sludge particles, and the modified papermaking black liquor can make the raw materials of the cementing material more uniformly dispersed and increase the solidification strength of the cementing material. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be further described in detail below with reference to the embodiments. In addition, it should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0023] In the description of the present application, it is necessary to understand that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0024] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0025] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include the direct contact of the first and second features, or can include the contact of the first and second features through another feature between them. Moreover, the "upper", "above" and "above" of the first feature to the second feature includes the vertical direction of the first feature above and oblique above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature includes the vertical direction of the first feature below and oblique below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0027] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0028] In the present application, "preferably" and "more preferably" are only used to describe the better effect of the embodiments, and should be understood as not limiting the protection scope of the present application. In the present application, the open technical features include both the closed technical solutions composed of the listed features and the open technical solutions containing the listed features. In the present application, if no special description is made, the numerical interval includes both ends of the numerical interval.

[0029] The present application provides a cementing material for high water content sludge, which comprises the following components in parts by weight: Portland cement 25-40 parts, lime 30-45 parts, fly ash 15-30 parts, modified papermaking black liquor 5-10 parts, bentonite 10-25 parts, and anti-dispersant 0.5-4 parts.

[0030] In the present application, Portland cement and lime are introduced into the formula, which can produce strength through hydration reaction and improve the mechanical properties of sludge. Meanwhile, fly ash is mixed, which can accelerate the hydration and strength generation in the alkaline environment created by Portland cement and lime, and has the effects of volcanic ash and micro aggregate, which can fill the pores of sludge and improve the compactness. In addition, bentonite and anti-dispersant are mixed in the formula of the present application. The bentonite can be part of the cementing material to form strength through hydration, which can adsorb free water molecules and reduce the attenuation of the hydration strength of the solidified material due to excessive water content. The incorporation of anti-dispersant is beneficial to the connection between the material and the sludge, blocks the excess free water, accelerates the dewatering of the sludge, and improves the solidification strength of the cementing material to the sludge particles.

[0031] Specifically, Portland cement can form strength through hydration reaction. In some embodiments, the strength grade of the Portland cement is not less than 42.5. The exemplary weight parts of the Portland cement are 25 parts, 30 parts, 35 parts, 40 parts, which are not limited to the above list.

[0032] Lime can adsorb a large amount of water, and hydration reaction can form strength, and create an alkaline environment to promote the hydration and chemical reaction of other materials. In some embodiments, the lime is quicklime, and the effective CaO content is not less than 85%. The exemplary weight parts of the lime are 30 parts, 35 parts, 40 parts, 45 parts, which are not limited to the above list.

[0033] Fly ash, as part of the cementing material, has the effects of micro aggregate and volcanic ash, which can strengthen the solidification and compactness of sludge, and occurs hydration reaction to form strength in the alkaline environment created by cement and lime. In some embodiments, fly ash adopts grade II fly ash. The exemplary weight parts of the lime are 15 parts, 20 parts, 25 parts, 30 parts, which are not limited to the above list.

[0034] Bentonite can also be used as part of the cementing material to participate in the hydration reaction to form strength, and at the same time, it has good water absorption to absorb the excess free water in the high water content sludge, and improve the overall hydration strength of the cementing material. The exemplary weight parts of the bentonite are 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, and are not limited to the above list.

[0035] In some embodiments, the anti-dispersant includes polyacrylamide and sodium polyacrylate. The incorporation of polyacrylamide is conducive to strengthening the bonding of the solidified material with the sludge, expelling the excess free water in the high water content sludge, accelerating the dewatering of the high water content sludge, and preventing excessive water content from affecting the solidification strength of the cementing material on the sludge particles. Sodium polyacrylate has extremely strong water absorption and can quickly absorb the excess water in the high water content sludge, accelerate the dewatering of the high water content sludge, and form a gel material that has a cementing effect on the sludge particles, which is conducive to the rapid solidification of the high water content sludge.

[0036] In some embodiments, the bentonite is sodium-based bentonite; and the polyacrylamide is anionic polyacrylamide. When sodium-based bentonite, anionic polyacrylamide, and sodium polyacrylate are simultaneously added to the cementing material of the high water content sludge, complex polymerization reactions occur in the alkaline environment formed after the hydration of quicklime. On the one hand, the sodium ions in the sodium-based bentonite will undergo ion exchange with the anion groups in the anionic polyacrylamide, and the carboxyl groups of the sodium polyacrylate will undergo ion exchange with the sodium ions between the layers of the bentonite. The above reactions will cause changes in the interlayer spacing of the bentonite, which is conducive to making the structure of the bentonite more loose, facilitating the entry and absorption of water molecules, and improving the water absorption of the bentonite, which is more conducive to the rapid dewatering of the high water content sludge. On the other hand, the small layers of the bentonite can adsorb the molecular chains of the anionic polyacrylamide and the colloidal particles of the sodium polyacrylate, and the anionic polyacrylamide molecular chains and the sodium polyacrylate can be attracted to each other through electrostatic interaction, hydrogen bonding, and van der Waals forces to form a complex network structure. When combined with the bentonite, a more complex face-network-face three-dimensional spatial network is formed, which is conducive to locking the sludge particles and forming a firm aggregate, thereby improving the solidification strength of the cementing material.

[0037] In some embodiments, the mass ratio of the polyacrylamide to the sodium polyacrylate is (1-2):1; and the mass ratio of the bentonite to the anti-dispersant is (4-5):1. Within the above ranges, the water absorption of the bentonite is improved, the rapid dewatering is achieved, and the solidification strength of the cementing material is improved.

[0038] In some embodiments, the modified papermaking black liquor is prepared by the following method: evaporative concentration of papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 to the high-concentration papermaking black liquor and reacting at 140-160°C for 0.5-1h to obtain the modified papermaking black liquor.

[0039] Preferably, the papermaking black liquor is papermaking black liquor produced in an alkaline pulping process; the concentration of the high-concentration papermaking black liquor is 60-70%.

[0040] It should be noted that in the alkaline pulping process, cellulose in the papermaking raw material is utilized and made into finished products, and lignin in the papermaking raw material is degraded and dissolved in the cooking liquor in the form of sodium lignin salt. Thus, alkali lignin, hemicellulose and residual alkali constitute the main components of the black liquor. A large amount of black liquor, if not treated or simply treated, is directly discharged into the environment, which will cause serious pollution to the environment. In the present application, the papermaking black liquor is evaporatively concentrated and sulfonated to obtain high-concentration modified papermaking black liquor containing lignin sulfonate. The lignin sulfonate can make the raw materials of the cementing material more uniformly dispersed, and is beneficial to dewatering and solidification. Further, the lignin sulfonate in the modified papermaking black liquor can, under the excitation of alkaline conditions, undergo graft copolymerization with polyacrylamide. The copolymerization product can agglomerate the tiny particles in the sludge into larger particles, and can also fill into the pores in the sludge to form a more compact cementing structure, thereby enhancing the cementing strength of the sludge and making it more easily solidified and treated.

[0041] Correspondingly, the present application also provides a preparation method of a cementing material for high-water-content sludge, comprising the following steps:

[0042] In weight parts, 25-40 parts of Portland cement, 30-45 parts of lime, 15-30 parts of fly ash, 5-10 parts of modified papermaking black liquor, 10-25 parts of bentonite and 0.5-4 parts of anti-dispersant are mixed to obtain the cementing material for high-water-content sludge.

[0043] In some embodiments, the mixing process is carried out with stirring at a speed of not less than 50 revolutions per second.

[0044] In addition, the above cementing material for high-water-content sludge is used in the solidification of high-water-content sludge. In some embodiments, the cementing material for high-water-content sludge is mixed into the sludge at a dosage of 4-6%; the cementing material for high-water-content sludge is uniformly stirred with the sludge, and is dewatered and solidified; the dewatered and solidified sludge is tested, and is applied in the field of base course filling, etc.

[0045] The present application is further described in detail below with specific embodiments.

[0046] Embodiment 1

[0047] The embodiment provides a cementing material for high-water-content sludge, which comprises the following components in parts by weight: 30 parts of portland cement, 35 parts of lime, 20 parts of fly ash, 6 parts of modified papermaking black liquor, 15 parts of anionic bentonite, 2 parts of polyacrylamide, and 1 part of sodium polyacrylate.

[0048] The modified papermaking black liquor is prepared by the following method: performing evaporation concentration treatment on papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 into the high-concentration papermaking black liquor and reacting at 150 DEG C for 0.5h to obtain the modified papermaking black liquor.

[0049] Embodiment 2

[0050] The embodiment provides a cementing material for high-water-content sludge, which comprises the following components in parts by weight: 25 parts of portland cement, 35 parts of lime, 25 parts of fly ash, 6 parts of modified papermaking black liquor, 10 parts of anionic bentonite, 1 part of polyacrylamide, and 1 part of sodium polyacrylate.

[0051] The modified papermaking black liquor is prepared by the following method: performing evaporation concentration treatment on papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 into the high-concentration papermaking black liquor and reacting at 150 DEG C for 0.5h to obtain the modified papermaking black liquor.

[0052] Embodiment 3

[0053] The embodiment provides a cementing material for high-water-content sludge, which comprises the following components in parts by weight: 25 parts of portland cement, 40 parts of lime, 20 parts of fly ash, 6 parts of modified papermaking black liquor, 20 parts of anionic bentonite, 2 parts of polyacrylamide, and 2 parts of sodium polyacrylate.

[0054] The modified papermaking black liquor is prepared by the following method: performing evaporation concentration treatment on papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 into the high-concentration papermaking black liquor and reacting at 150 DEG C for 0.5h to obtain the modified papermaking black liquor.

[0055] Embodiment 4

[0056] The embodiment provides a cementing material for high-water-content sludge, which comprises the following components in parts by weight: 29 parts of portland cement, 35 parts of lime, 20 parts of fly ash, 6 parts of modified papermaking black liquor, 12 parts of anionic bentonite, 2 parts of polyacrylamide, and 1 part of sodium polyacrylate.

[0057] The modified papermaking black liquor is prepared by the following method: performing evaporation concentration treatment on papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 into the high-concentration papermaking black liquor and reacting at 150 DEG C for 0.5h to obtain the modified papermaking black liquor.

[0058] Embodiment 5

[0059] The embodiment provides a cementing material for high-water-content silt, which comprises the following components in parts by weight: 29 parts of Portland cement, 30 parts of lime, 20 parts of fly ash, 6 parts of modified papermaking black liquor, 16 parts of anionic bentonite, 2 parts of polyacrylamide, and 2 parts of sodium polyacrylate.

[0060] The modified papermaking black liquor is prepared by the following method: performing evaporation concentration treatment on papermaking black liquor to obtain high-concentration papermaking black liquor; adding Na2SO3 to the high-concentration papermaking black liquor and reacting at 150 DEG C for 0.5 h to obtain the modified papermaking black liquor.

[0061] Comparative Example 1

[0062] The comparative example provides a cementing material for high-water-content silt, which comprises the following components in parts by weight: 30 parts of Portland cement, 35 parts of lime, 20 parts of fly ash, 15 parts of anionic bentonite, and 1 part of sodium polyacrylate.

[0063] Comparative Example 2

[0064] The comparative example provides a cementing material for high-water-content silt, which comprises the following components in parts by weight: 30 parts of Portland cement, 35 parts of lime, 20 parts of fly ash, 15 parts of anionic bentonite, and 1 part of sodium polyacrylate.

[0065] Comparative Example 1

[0066] The comparative example provides a cementing material for high-water-content silt, which comprises the following components in parts by weight: 30 parts of Portland cement, 35 parts of lime, 20 parts of fly ash, 15 parts of anionic bentonite, and 1 part of sodium polyacrylate.

[0067] Comparative Example 2

[0068] The comparative example provides a cementing material for high-water-content silt, which comprises the following components in parts by weight: 30 parts of Portland cement, 35 parts of lime, 20 parts of fly ash, 15 parts of anionic bentonite, and 1 part of sodium polyacrylate.

[0069] The test soil is river channel dredged silt, the water content of which is 92%, and the organic matter content is 8.3%. When molding, the cementing material for high-water-content silt is mixed at 5% of the mass of the dredged silt.

[0070] During the test, the CBR, unconfined compressive strength forming and testing are carried out according to the method specified in the Highway Geotechnical Test Specification (JTG 3420-2020), and the unconfined compressive strength loss under the condition of immersion is tested to evaluate the water resistance of the dredged silt solidified soil. The test results of Example 1 to Example 5, Comparative Example 1 to Comparative Example 2, and Comparative Example 1 to Comparative Example 2 are shown in Table 1.

[0071] Table 1 Test results of Example 1 to Example 5, Comparative Example 1 to Comparative Example 2, and Comparative Example 1 to Comparative Example 2

[0072]

[0073] As can be seen from Table 1, Comparative Example 1 to Example 5 and Comparative Example 1, Comparative Example 2, Comparative Example 1 and Comparative Example 2, the incorporation of a specific type of bentonite, anti-dispersant and modified papermaking black liquor plays a crucial role in improving the CBR and unconfined compressive strength of the solidified dredged silt soil. The cementing material provided in Example 1 to 5 for resource treatment of high water content dredged silt has a much better solidification effect on dredged silt than traditional cement and lime. The cementing material provided in the present embodiment for resource treatment of high water content dredged silt has excellent solidification effect on dredged silt, and can be applied to the solidification treatment of high water content and high organic matter dredged silt. The solidified dredged silt can be used for foundation backfilling, roadbed filling and other engineering, which is beneficial to the treatment and resource utilization of dredged silt, and reduces the pollution to the environment.

[0074] In the description of the present specification, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The above disclosure is only a preferred embodiment of the present application, and of course cannot limit the scope of the right of the present application, so the equivalent changes made according to the claims of the present application are still within the scope of the present application.

Claims

1. A cementitious material for use with high water content sludge, characterized in that, The cementing material for high water content sludge comprises the following components in parts by weight: silicate cement 25-40 parts, lime 30-45 parts, fly ash 15-30 parts, modified papermaking black liquor 5-10 parts, bentonite 10-25 parts, and anti-dispersant 0.5-4 parts. The anti-dispersant is polyacrylamide and sodium polyacrylate, and the mass ratio of the polyacrylamide to the sodium polyacrylate is (1-2):

1. The modified papermaking black liquor is prepared by the following method: The papermaking black liquor is subjected to evaporation and concentration treatment to obtain high-concentration papermaking black liquor; Na2SO3 is added to the high-concentration papermaking black liquor and reacted at 140-160 DEG C for 0.5-1 h to obtain the modified papermaking black liquor; The papermaking black liquor is produced in an alkaline pulping process, and the concentration of the high-concentration papermaking black liquor is 60-70%.

2. The cementitious material for high water content sludge according to claim 1, characterized by, The bentonite is sodium-based bentonite. The polyacrylamide is anionic polyacrylamide.

3. The cementitious material for high water content sludge according to claim 2, characterized by, The mass ratio of the bentonite to the anti-dispersant is (4-5):

1.

4. The cementitious material for high water content sludge according to claim 1, characterized by, The strength grade of the silicate cement is not less than 42.

5. The lime is quicklime, and the effective CaO content is not less than 85%. The fly ash is grade II fly ash.

5. A method for producing a cementing material for high water content sludge according to any one of claims 1 to 4, characterized by, The cementing material for high water content sludge is prepared by mixing the following components in parts by weight: silicate cement 25-40 parts, lime 30-45 parts, fly ash 15-30 parts, modified papermaking black liquor 5-10 parts, bentonite 10-25 parts, and anti-dispersant 0.5-4 parts.

6. The use of the cementing material for high water content sludge according to any one of claims 1-4 in the solidification of high water content sludge.

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