A sludge solidification treatment method

Abstract

The present invention relates to a sludge solidification treatment method, comprising the following steps: S1 calcining expanded perlite with a particle size of 1.18mm-2.36mm at 800℃-1250℃; S2 evenly mixing the calcined expanded perlite with the sludge to be solidified, and sealing and stewing the material for 22h-26h to allow part of the moisture in the sludge to fully enter the microporous structure of the expanded perlite; S3 stirring and mixing a curing agent with the expanded perlite and sludge mixture to obtain a mixture; S4 pouring the mixture into a mold on a vibrating table in layers, and fully vibrating it until all bubbles are discharged; S5 sealing the mold with plastic wrap and placing it in a constant temperature and humidity curing box, and demoulding it after curing for 24h; S6 continuing to seal and cure the demoulding mixture in a constant temperature and humidity curing box to a predetermined age. The present invention makes full use of the lightweight aggregate function of the expanded perlite, exerts its volcanic ash activity, can significantly improve the long-term strength of the solidified sludge, and can achieve efficient utilization of the sludge.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment, and in particular relates to a sludge solidification treatment method. Background Art

[0002] To ensure the safe operation of lakes and rivers, sediment dredging is necessary, and large quantities of silt urgently need to be handled. Storage and landfill are the two main options for silt disposal. Dredged silt has a high water content, strong fluidity, and high porosity. Much of it is rich in organic matter, making it slow to dry naturally. Even landfilled silt is not self-stable. Furthermore, with the increasing shortage of urban land, storage is no longer sustainable.

[0003] Dredged sludge has a high moisture content. This excess moisture, exceeding the water content required for hydration of the curing agent, is stored as pore water in the solidified sludge. This results in a low volume of hydration products, making it difficult to effectively gel the sludge particles. This, in turn, reduces the strength of the solidified sludge, making the solidification method uneconomical. High sludge moisture content is a major challenge facing sludge reduction and resource utilization, and innovative methods are urgently needed to reduce it to a reasonable range.

[0004] Currently, the main methods for dewatering high-moisture sludge include natural airing, mechanical dehydration, pre-pressing drainage, geotube bag filtration dehydration, and chemical flocculation dehydration. However, due to the unique properties of sludge, dewatering methods, whether by changing the loading method or employing novel devices or combined chemical methods, are energy-intensive and costly. To address this issue, the present invention proposes using porous materials to absorb moisture from the sludge. This not only maintains the moisture required for hydration of the curing agent, but also allows it to remain within the solidified sludge to perform its internal curing function, achieving the goal of "cement separation, dewatering, and efficiency enhancement." Summary of the Invention

[0005] The technical purpose of the present invention is to propose a sludge solidification treatment method to address the problem of high water content in dredged sludge solidification treatment, so that part of the water in the sludge is separated from the mud particles, leaving as much water as possible as required by the solidifying agent, and leaving the excess water to avoid it from being stored in the solidified sludge to form pores and reduce the strength of the solidified sludge.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a sludge solidification treatment method, comprising the following steps:

[0007] S1: calcining expanded perlite with a particle size of 1.18 mm to 2.36 mm at 800° C. to 1250° C.

[0008] S2: After the calcined expanded perlite is evenly mixed with the sludge to be solidified, the mixture is sealed and stewed for 22h-26h to allow part of the moisture in the sludge to fully enter the microporous structure of the expanded perlite;

[0009] S3 stirs and mixes the curing agent with the expanded perlite and silt mixture to obtain a mixture:

[0010] S4: pouring the mixture into a mold on a vibration table in layers and vibrating it thoroughly until all bubbles are expelled;

[0011] S5: Seal the mold with plastic wrap and place it in a constant temperature and humidity curing box for 24 hours before demoulding;

[0012] S6: The demoulded mixture is sealed and cured in a constant temperature and humidity curing box until the predetermined age.

[0013] Preferably, the mass water absorption rate of the expanded perlite is in the range of 600-800%.

[0014] Preferably, the cylinder compressive strength of the expanded perlite is 60 kPa.

[0015] Preferably, the curing agent is an inorganic gelling material.

[0016] Preferably, the inorganic gelling material is cement.

[0017] Preferably, the amount of expanded perlite added is 4% of the mass of the silt.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a sludge solidification treatment method that can fully utilize the lightweight aggregate function of expanded perlite, exert its volcanic ash activity, significantly improve the long-term strength of solidified sludge, achieve efficient utilization of sludge, reduce environmental problems, and open up new ideas for sludge precipitation.

[0020] The present invention provides a sludge solidification treatment method, which can achieve partial cement separation by adding expanded perlite, reduce the amount of curing agent used, and achieve the same or even better curing effect, which is in line with the green and low-carbon development strategy goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Expanded perlite with different particle size ranges.

[0022] Figure 2 is the water absorption rate of expanded perlite with different particle sizes.

[0023] Figure 3 This is a flow chart for preparing solidified sludge according to the present invention.

[0024] Figure 4 This is a cross-sectional view of the solidified sludge sample prepared in the present invention.

[0025] Figure 5This is a comparison chart of the compressive strength of different mixing orders when solidifying sludge in the present invention.

[0026] Figure 6 This is the stress-strain curve (T=28d) of the samples tested with different mixing orders in the present invention.

[0027] Figure 7 This is the moisture content of the sample in the order of incorporation tested in the present invention (T=28d).

[0028] Figure 8 The figure shows the strength comparison between the expanded perlite dosage and the cement curing agent dosage in the present invention.

[0029] In the figure, S: silt, E: expanded perlite, and C: cement. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] like Figure 3 As shown, as a preferred embodiment of the present invention, this embodiment provides a sludge solidification treatment method, comprising the following steps:

[0032] S1: calcining expanded perlite with a particle size of 1.18 mm to 2.36 mm at 800° C. to 1250° C.

[0033] S2: Evenly mix the calcined expanded perlite with silt with a moisture content of 200%, and seal and stew for 22-26 hours to allow part of the moisture in the silt to fully enter the microporous structure of the expanded perlite. The amount of expanded perlite is 4% of the silt mass.

[0034] S3: Stirring and mixing the curing agent with the expanded perlite and silt mixture to obtain a mixture. The curing agent used in this embodiment is cement, and the amount of cement is 12% of the mass of the silt:

[0035] S4: pouring the mixture into a mold on a vibration table in layers and vibrating it thoroughly until all bubbles are expelled;

[0036] S5: Seal the mold with plastic wrap and place it in a constant temperature and humidity curing box for 24 hours before demoulding;

[0037] S6: The demoulded mixture is sealed and cured in a constant temperature and humidity curing box until the predetermined age. The cross section of the solidified sludge sample is as follows: Figure 4 shown.

[0038] In some preferred embodiments, the mass water absorption of the expanded perlite is in the range of 600-800%.

[0039] In some preferred embodiments, the expanded perlite has a cylinder compressive strength of 60 kPa.

[0040] Generally speaking, the larger the particle size of expanded perlite, the better its water absorption performance. In this patent, the expanded perlite needs to exert its water absorption performance, but it cannot only exert its water absorption performance. Therefore, the particle size of the expanded perlite needs to be scientifically selected. When testing the water absorption performance of expanded perlite with different particle sizes, it was found that Figure 1 As shown in the figure, expanded perlite with a particle size of 1.18mm-2.36mm has the best water absorption performance after calcination and can provide a silt skeleton during silt solidification. Therefore, expanded perlite with a particle size of 1.18mm-2.36mm is the best choice for silt solidification.

[0041] The expanded perlite used in the above examples is calcined at 800°C-1250°C to produce high-silicon particles. These particles exhibit pozzolanic activity and a microporous structure within them. They are lightweight, porous, and offer thermal and sound insulation properties. The polar hydrophilic groups on their surface provide strong adsorption capacity, with a water absorption rate of 4-9 times their own weight. When the calcined expanded perlite is added to dredged mud, its initial function is to partially separate the water from the mud. It then forms a core and builds a mud skeleton. The pozzolanic activity of the expanded perlite, combined with inorganic cementitious materials, creates a cementing effect, thereby enhancing the strength of the solidified mud.

[0042] In order to study the optimal ratio and the optimal implementation method, the inventors of this application conducted water absorption performance tests on expanded perlite with different particle sizes. Figure 1 and Figure 2 As shown in the figure, the water absorption capacity of expanded perlite with different particle sizes was tested for tap water, deionized water and sludge liquid. The test results are shown in the figure. Figure 2 As shown, the test results show that the expanded perlite with a particle size of 1.18mm-2.36mm has the best water absorption performance.

[0043] During the development of the present invention, it was found that different mixing orders of silt, expanded perlite and cement would result in different compressive strengths of solidified silt samples obtained later. Therefore, the strength tests of solidified silt obtained in different mixing orders were conducted at 7 days, 14 days and 28 days respectively. The test results are as follows: Figure 5As shown, the test experimental groups are silt mixed with cement (SC in the figure), silt mixed with expanded perlite and then mixed with cement (SEC in the figure), silt mixed with cement and then mixed with expanded perlite (SCE in the figure), cement mixed with expanded perlite and then mixed with silt (CES in the figure). The stewing material in the figure is to first mix the calcined expanded perlite with silt with a moisture content of 200% evenly, seal and stew the material for 22h-26h, and then stir and mix the curing agent with the mixture of expanded perlite and silt to obtain a mixture. The test results show that the test strength of the solidified silt obtained by first mixing the expanded perlite and silt and stewing the material and then adding cement to the mixture is higher than the compressive strength of the other units in the same period during the three strength cycles.

[0044] On this basis, it was also found that the final strength of the solidified silt sample obtained by mixing expanded perlite with silt and sealing it for 22-26 hours before mixing it with cement (stewing in the figure) was significantly higher than the compressive strength of the solidified silt sample obtained by mixing the three in the optimal order.

[0045] Inspired by the compressive strength test results, the solidified sludge obtained by the five different mixing methods in the above compressive strength test was subjected to tensile tests using a tensile testing machine, and the stress-strain curves were obtained as shown in the following figure. Figure 6 As shown, the test results show that the tensile strength of the solidified silt sample obtained by first mixing the expanded perlite with the silt, sealing and stewing the material for 22h-26h and then mixing it with cement (stewing material in the figure) after completing the subsequent steps is significantly higher than the tensile strength of the solidified silt sample obtained by mixing the three in the optimal order.

[0046] In order to trace the internal principle of the influence of different mixing methods on the compressive strength and tensile strength of solidified sludge, the inventors tested the moisture content of the mixtures obtained by different mixing methods. The test results are as follows: Figure 7 As shown in the figure, the test results show that the moisture content of SCE and stewing materials is similar, but the compressive strength and tensile strength of the solidified sludge tests formed by the two mixing methods are quite different. The reason is that the stewing process adds expanded perlite to the dredged sludge, which achieves the effect of separating part of the water in the sludge in the initial stage, and at the same time forms a core in the sludge and constructs the sludge skeleton; and after the addition of cement, the calcined expanded perlite can combine with inorganic cementitious materials to form a cementing effect due to its volcanic ash activity, thereby enhancing the compressive strength and tensile strength of the solidified sludge sample.

[0047] Regarding the cement content, the inventors used different cement content to obtain solidified sludge samples and then conducted compressive strength tests. The test results are as follows: Figure 8 shown.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A sludge solidification treatment method comprising the following steps: S1: calcining expanded perlite with a particle size of 1.18 mm to 2.36 mm at 800° C. to 1250° C. S2: After the calcined expanded perlite is evenly mixed with the sludge to be solidified, the mixture is sealed and stewed for 22h-26h to allow part of the moisture in the sludge to fully enter the microporous structure of the expanded perlite; S3 stirs and mixes the curing agent with the expanded perlite and silt mixture to obtain a mixture: S4: pouring the mixture into a mold on a vibration table in layers and vibrating it thoroughly until all bubbles are expelled; S5: Seal the mold with plastic wrap and place it in a constant temperature and humidity curing box for 24 hours before demoulding; S6: The demoulded mixture is sealed and cured in a constant temperature and humidity curing box until the predetermined age.

2. A sludge solidification treatment method according to claim 1, characterized in that: The mass water absorption rate of the expanded perlite is in the range of 600-800%.

3. A sludge solidification treatment method according to claim 1, characterized in that: The cylindrical compressive strength of the expanded perlite is 60 kPa.

4. The sludge solidification treatment method according to claim 1, characterized in that: The amount of expanded perlite added is 4% of the mass of the silt.

5. The sludge solidification treatment method according to claim 1, characterized in that: The curing agent is an inorganic gelling material.

6. A sludge solidification treatment method according to claim 5, characterized in that: The inorganic gelling material is cement.

7. A sludge solidification treatment method according to claim 6, characterized in that: The cement content is 12% of the sludge mass.

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